Overall, we believe that Atara is a leading allogeneic T-cell immunotherapy company with a robust and late stage oncology pipeline and potentially transformative T-cell immunotherapies for MS and other viral diseases. With tabelecleucel poised to potentially become the first approved off-the-shelf T-cell therapy and a robust pipeline of high potential candidates, our ambition is to be recognized as the leader in off-the-shelf T-cell immunotherapy.Ebvallo™ (Tab-cel®)

Tabelecleucel for EBV+ PTLD following HCT or SOT

Since its discovery as the first human oncovirus, EBV has been implicated in the development of a wide range of diseases, including lymphomas and other cancers. EBV is widespread in human populations and persists as a lifelong, asymptomatic infection. In healthy individuals, a small percentage of T-cellsT cells are devoted to keeping EBV in check. In contrast, immunocompromised patients, such as those undergoing hematopoietic cell transplants or HCT,(HCT) or solid organ transplants or SOT,(SOT) have a reduced ability to control EBV. Left without appropriate immune surveillance, EBV transformedEBV-transformed cells can, in some patients, proliferate and cause an aggressive, life-threatening cancer called EBV+ PTLD.PTLD. Nearly all cases of PTLD that occur following HCT are EBV positive while approximately 70%60% of PTLD cases that occur following SOT are EBV positive. Approximately 10-15% of

Historical studies suggest a high unmet medical need for improved therapies in patients with EBV+ PTLD patients are children. Patients with EBV+ PTLD are currently treated withwho have failed rituximab or rituximab plus chemotherapy, when systemic treatment is indicated, with approximately 50-60%40% to 60% of patients either not responding to or progressing following this first line of therapy. Historical studies suggest a high unmet medical need for improved therapies in patients with EBV+ PTLD who have failed rituximab. MedianExpected median overall survival in patients with EBV+ PTLD following HCT who have failed rituximab-based first line therapy is 16-56 days, with a one-year survival rate of approximately 23% based on our evaluation of available historical outcomes data. One-1.7 months, and two-year survival following incomplete response to rituximab infor patients with high-risk EBV+ PTLD after following SOT who have failed rituximab-based first line therapy, the median overall survival is 36% and 0%, respectively.approximately 3.3 months. The use of chemotherapy in patients with EBV+ PTLD who have failed rituximab is frequently associated with significant rates of treatment-related mortality due to the frailty of the patients and severe toxicities associated with chemotherapy.

We believe that the global commercial opportunity for PTLD is attractive. We expect the number of EBV+ PTLD patients to grow over time as a result of increases in the number of transplant procedures and an increasing rate of PTLD following these procedures. Based on our market research, we estimate that in 2019, approximately 164,000 HCT and SOT transplant procedures are expected to be performedthere were several hundred EBV+ PTLD patients who failed rituximab or rituximab plus chemotherapy in the United States,U.S. in 2019.

Tab-cel® (Ebvallo™) for EBV+ PTLD

In June 2015, we licensed certain patent rights, know-how and a library of T cells and cell lines specific to EBV from MSK under an exclusive license agreement. In accordance with the European Union, or EU, Australia, Canada, China, Japan, South Korealicense agreement, we agreed to use commercially reasonable efforts to commercialize the licensed products and Turkey,to make milestone payments with this number expected to increase to approximately 207,000 by 2024, predominantly due to increases in bone marrow, peripheral blood and umbilical cord blood donation and more haploidentical transplants. Similarly, the number of cases of EBV+ PTLD is expected to increase from approximately 4,700 in 2019 to 6,000 in 2024 duerespect to the uselicensed programs and to make royalty payments to MSK to the extent product candidates arising from the collaboration are commercialized. Our first commercial product, Ebvallo, is part of more potent immuno-suppression in haploidentical transplants.this MSK collaboration and targets EBV.

Our most advanced T-cell immunotherapy product candidate, tabelecleucel,Tab-cel® (Ebvallo™) is an allogeneic EBV-specific T-cell immunotherapy that is approved in the EU and UK and currently being investigatedin Phase 3 development in the U.S. for the treatment of patients with EBV+ PTLD who have failed rituximab. In February 2015, the FDA granted tabelecleucel BTD or rituximab plus chemotherapy. Tab-cel is also under development for other EBV+ diseases with significant unmet medical need through a Phase 2 multi-cohort study that was initiated in the treatmentthird quarter of patients with EBV+ PTLD after HCT who have failed rituximab. BTD is an FDA process designed to accelerate the development and review of drugs intended to treat a serious condition when early trials show that the drug may be substantially better than current treatment. In October 2016, tabelecleucel was accepted into the EMA PRIME regulatory pathway for the same indication, providing enhanced regulatory support. In addition, tabelecleucel2020.

Tab-cel has received orphan status inBreakthrough Therapy Designation (BTD) from the United StatesU.S. Food and European UnionDrug Administration (FDA) for the treatment of patients with EBV+ PTLD after HCT who have failed rituximab and orphan designation in the U.S. and European Union (EU) for the treatment of patients with EBV+ PTLD following HCT or SOT. In December 2016, we announced that we had reached agreement with the FDA on the designs of two Phase 3 trials for tabelecleucel intended to support approval in two separate indications, the treatment of EBV+ PTLD following HCT and SOT in patients who have failed rituximab. In December 2017, following discussion with the FDA of manufacturing and comparability data generated on material manufactured by our contract manufacturing organization, we initiated these trials in the United States. We expect to expand these trials geographically to include Europe, Canada, and Australia.

The Phase 3 MATCH trial (EBV+ PTLD following HCT) is a multicenter, open label, single arm trial designed to enroll approximately 35 patients with EBV+ PTLD following HCT who have failed rituximab. The Phase 3 ALLELE trial (EBV+ PTLD following SOT) is a multicenter, open label trial with two non-comparative cohorts. Each cohort is designed to enroll approximately 35 patients. The first cohort will include patients who previously received rituximab monotherapy, and the second cohort will include patients who previously received rituximab plus chemotherapy. Both cohorts are planned to enroll concurrently. The primary endpoint of both the MATCH and ALLELE trials is confirmed best objective response rate, or ORR, defined as the percent of patients achieving either a complete or partial response to treatment with tabelecleucel confirmed after the initial tumor assessment showing a response. The protocols are designed to rule out a 20% ORR as the null hypothesis. This means that if the lower bound of the 95% confidence interval on ORR among patients receiving at least one dose of tabelecleucel exceeds 20% at the end of the study, then the trial would be expected to meet the primary endpoint for the treatment of PTLD. For example, assuming anticipated enrollment of 35 patients in MATCH, an observed ORR above approximately 37% would be expected to meet the primary endpoint. In ALLELE, each of the two cohorts with an anticipated enrollment of 35 patients will be analyzed separately with respect to the primary endpoint and, similarly, as an example, with 35 patients enrolled in either cohort, an observed ORR above approximately 37% would be expected to meet the primary endpoint. Secondary endpoints for both trials include duration of response, overall survival, safety, quality of life metrics, and other measures to evaluate its health economic impact. A safety committee will meet periodically to monitor for safety. Results from the first tabelecleucel Phase 3 study, or cohort in the case of ALLELE, to reach the primary endpoint are expected to be available in the first half of 2019.

In clinical trialsstudies conducted at MSK that have enrolled patients with EBV+ PTLD following HCT and SOT, efficacy following treatment with tabelecleuceltab-cel monotherapy compared favorably with historical data in these patient populations. Patients with EBV+ PTLD after HCT who have failed rituximab and were treated with tabelecleuceltab-cel had one-yeartwo-year overall survival of approximately 70%83% in two separate clinical trials.studies. In the setting of EBV+ PTLD after SOT in patients who have failed rituximab,, similar results were observed, with one-yeartwo-year overall survival of approximately 60%86% in tabelecleucel-treatedtab-cel-treated patients. A response rate of greater than or equal to 50% was observed in HCT and SOT patients in these studies.

In June 2016,December 2017, we openedinitiated two Phase 3 studies for tab-cel intended to support approval in two separate indications, the treatment of EBV+ PTLD following HCT (which was referred to as the MATCH study) and SOT in patients who have failed rituximab (which was referred to as the ALLELE study). In 2019, after discussion and alignment with regulators, we combined MATCH and ALLELE into a single study (which we now refer to as the ALLELE study) that now consists of an HCT cohort for EBV+ PTLD patients who have failed rituximab, and a single SOT cohort for EBV+ PTLD patients who have failed prior treatment with rituximab with or without chemotherapy. Additionally, we expanded the ALLELE study geographically to include clinical sites in Europe and Canada.

In the third quarter of 2020, we completed an interim analysis for the ALLELE study. Data from the interim analysis showed a 50 percent objective response rate (ORR) to tab-cel with independent oncologic and radiographic assessment (IORA) in patients with relapsed-refractory EBV+ PTLD following HCT or SOT, that had reached at least six months follow-up after the ORR assessment. This ORR is consistent with previously published investigator assessed data. The tab-cel safety profile is also consistent with previously published data, with no new safety signals. In December 2022, we presented updated interim analysis and safety results from the ALLELE study and updated efficacy and safety data from two single-center, open-label studies, and multicenter expanded access protocol, or EAP, trial. The trial is currently open at more than ten clinical sitesprogram in the United States. The primary objective of this trial is to provide tabelecleucel monotherapy to patients with EBV-associated diseases or certain EBV positive malignancies for whom there are no other therapeutic options. Key secondary objectives include evaluation of efficacy and safety through a robust collection of data. We recently announced the presentation of positive interim results from this multicenter EAP trialEBV+ Leiomysosarcomas at the 59th2022 American Society of Hematology or ASH, Annual Meeting. Efficacy resultsIn December 2023, we presented new data for patients with relapsed or refractory (r/r) or treatment-naïve EBV+ PTLD involving the central nervous system following SOT or HCT. An ORR of 77.8% was observed in 1118 central nervous system (CNS) EBV+ PTLD patients including first line PTLD, and the estimated one-year overall survival rate (OS) was 70.6%. The one-year OS for responders was 85.7% versus 0% for non-responders. In January 2024, data from the planned Phase 3 populationsALLELE study that was published in The Lancet Oncology showed a 51.2% objective response rate and 23-month median duration of response in r/r EBV+ PTLD patients and that tab-cel was well tolerated with EBV+ PTLD following HCTno events of graft-versus-host disease as related to tab-cel.

In October 2021, we entered into the Pierre Fabre Commercialization Agreement, pursuant to which we granted to Pierre Fabre an exclusive, field-limited license to commercialize and SOT who had failed rituximab were consistent with the single-institution safety profile and response rates previously reported by our collaborating investigators at MSK. The response rates in both the five evaluable HCT patients treateddistribute Ebvallo in the EAPInitial Territory. In September 2022, we amended the Pierre Fabre Commercialization Agreement to receive an additional $30 million milestone payment from Pierre Fabre in exchange for a reduction in royalties and the six evaluable SOT patients was greater than 70%. Ansupply price mark up on Ebvallo purchased by Pierre Fabre. See section ‘Terms of Certain License and Collaboration Agreements’ below for additional patient with EBV+ PTLD following HCT remains alive but was not evaluable duedetails. In December 2022, we sold a portion of our right to lackreceive royalties and certain milestones in Ebvallo under the Pierre Fabre Commercialization Agreement to HCRx for a total investment amount of post-baseline assessment. We believe these results are consistent with$31.0 million, subject to a repayment cap between 185% and 250% of the tabelecleucel profile observedtotal investment amount by HCRx.

On October 31, 2023, we entered into the A&R Commercialization Agreement, which became effective in December 2023. Pursuant to the A&R Commercialization Agreement, Pierre Fabre’s exclusive rights to research, develop, manufacture, commercialize and distribute tab-cel (Ebvallo) will be expanded to include all other countries in the Phase 2 trials conducted at MSK. The Phase 3 trialsworld (Additional Territory) in addition to the Initial Territory (together, the Territory), subject to our performance of certain obligations as described below. In December 2023, upon the effective date of the A&R Commercialization Agreement, we met the contractual right to receive an additional upfront cash payment of $20.0 million for tabelecleucelthe expanded exclusive license grant, for which such cash was received in January 2024. We will also be entitled to receive an aggregate of up to $620.0 million in additional milestone payments upon achieving certain regulatory and commercial milestones relating to tab-cel in the Additional Territory, including up to $100.0 million in potential regulatory milestones through BLA approval. Of the $100.0 million in potential regulatory milestones, we expect to receive $20.0 million in April 2024 based on the positive pre-BLA meeting, an additional $20.0 million in connection with BLA acceptance, and up to $60.0 million in potential regulatory milestones in connection with BLA approval.

We are expectedeligible to enrollreceive significant double-digit tiered royalties as a percentage of net sales of tab-cel (Ebvallo) in the same EBV+ PTLD patient populations. Tabelecleucel was generally well toleratedTerritory until the later of 12 years after the first commercial sale in this study population. each such country, the expiration of specified patent rights in each such country, or the expiration of all regulatory exclusivity for tab-cel in each such country. Royalty payments may be reduced in certain specified customary circumstances. Royalties and milestones from the commercialization of Ebvallo in the Initial Territory remain subject to the HCRx Agreement.

In this study, five patients experienced treatment-related SAEs. One patient died due to PTLD disease progression. Two possibly related cases of graft versus host disease, or GvHD,November 2021, we submitted an EU marketing authorization application (MAA) for tab-cel in patients with EBV+ PTLD. In December 2022, the EC granted marketing authorization for Ebvallo under the “exceptional circumstances” regulatory pathway as a monotherapy for the treatment of adult and pediatric patients two years of age and older with r/r EBV+ PTLD following HCT were reported. A tumor flare who have received at least one prior therapy. For SOT patients, prior therapy includes chemotherapy unless chemotherapy is inappropriate. Our request to transfer the marketing authorization for Ebvallo to Pierre Fabre was observedadopted by the EC in one patient with EBV+HIV-associated plasmablastic lymphoma that resolved without clinical sequelae.

With respect to the total safety population following treatment with tabelecleucel, few treatment-related SAEs have been observed. Among 173 patients treated with tabelecleucel in clinical trials, there have been 12 patients with possibly related SAEs, with no infusion related toxicities, no cytokine release syndrome and three possibly related cases of GvHD.

We are also pursuing marketing approval of tabelecleucelFebruary 2023. Pierre Fabre commenced Ebvallo launch activities in the first European Union. countries in the first quarter of 2023 and is progressively launching Ebvallo on a country-by-country basis. Under the “exceptional circumstances” marketing authorization, Pierre Fabre is subject to annual reassessments of certain ongoing post-marketing obligations to continue confirmation of the benefits of Ebvallo. The annual reassessments will determine whether the Ebvallo marketing authorization should be maintained, changed, or suspended, based on Pierre Fabre’s fulfillment of post-marketing obligations and the risk/benefit profile of Ebvallo.

In March 2016,October 2022, we filed the EMA issued a positive opinionMAA for orphan drug designation for tabelecleucelEbvallo with the Medicines and Healthcare Products Regulatory Authority (MHRA) in the United Kingdom (UK). In May 2023, the MHRA granted Ebvallo marketing authorization in the UK for the treatment of patients with EBV+ PTLD. In October 2016, and the marketing authorization was subsequently transferred to Pierre Fabre.

We have performed extensive studies demonstrating analytical comparability between the tab-cel manufacturing process versions used for the pivotal ALLELE study and that intended for commercialization. Comprehensive comparability analyses covered 21 key attributes for potency, purity and alloreactivity. We believe analytic comparability between tab-cel process versions has been demonstrated based on well-established statistical methodology and application of International Council for Harmonization (ICH) guidelines and is further supported by significant and consistent clinical experience. These comparability data analyses were submitted to the EMA Committeethrough our MAA filing. EMA stated in its assessment report issued following approval of the MAA for Medicinal Productstab-cel by the EC that it considered comparability of the intended commercial product with the clinically used product to be shown.

We have been engaged in discussions with the FDA regarding a potential biologics license application (BLA) submission for Human Usetab-cel in the United States, including on (i) the content of chemistry, manufacturing and controls (CMC) module 3 and the Committeeassessment of comparability between the product used in the pivotal ALLELE study and that intended for Advanced Therapies granted tabelecleucel accesscommercialization and (ii) the clinical data package requirements.

In February 2022, we held a Type B CMC meeting with the FDA to discuss comparability between the intended commercial and pivotal clinical trial process versions. This meeting did not result in alignment on comparability and the FDA initially recommended we conduct a clinical study with commercial product as the FDA did not agree that comparability has been demonstrated between product used in the pivotal ALLELE study and the intended commercial product. Following further discussions, the FDA recommended a potential path to a BLA submission without the need for a new clinical study.

We subsequently held another meeting with the FDA to discuss topics relating to CMC, which culminated in clear guidance and agreement on specific CMC module 3 requirements for a potential BLA submission. Following this meeting, we filed an amendment to the EMA’sInvestigational New Drug (IND) application for tab-cel to provide additional CMC information requested by the FDA.

In 2023, we held a number of meetings with the FDA on clinical aspects and CMC for a potential BLA submission for tab-cel. Following such discussions, we aligned with the FDA on analytical comparability between manufacturing process versions of tab-cel. This alignment supports our ability to pool the pivotal clinical trial data from different process versions in a tab-cel BLA submission.

We recently established PRIMEheld a pre-BLA meeting with the FDA to discuss various aspects of our proposed BLA submission, which supports our plan to submit the tab-cel BLA in the second quarter of 2024. Of the $100.0 million in potential regulatory initiativemilestones that we may be entitled to receive through approval from Pierre Fabre pursuant to the terms of the A&R Commercialization Agreement, we expect to receive $20.0 million in April 2024 based on the positive pre-BLA meeting, an additional $20.0 million in connection with BLA acceptance, and up to $60.0 million in potential regulatory milestones in connection with BLA approval.

Tab-cel Multi-Cohort Study

We continue to pursue development of tab-cel in additional patient populations, with a primary focus on immunodeficiency-associated lymphoproliferative diseases (IA-LPDs), given the commonality of their EBV-driven mechanism of disease in immunocompromised patients, high unmet medical needs and positive clinical data to date with tab-cel. In patients where previous treatments have failed, the objective response rates, including complete response, were 33.3% (three out of nine patients) in AID-LPD and 37.5% (three out of eight patients) in PID-LPD groups. Tab-cel was generally well-tolerated with a favorable safety profile consistent with previously published clinical studies. These clinical data demonstrated that tab-cel was well-tolerated and showed encouraging clinical activity in this patient population, with objective response rates ranging from 50% (two out of four patients) to 80% (four out of five patients). The overall survival (OS) rate at one year in patients with EBV viremia treated in the EAP-201 study was 100 percent for a median follow-up of 14.6 months (min 12.2, max 17.8).

In the third quarter of 2020, we initiated a Phase 2 multi-cohort study which comprises a total of five patient populations, including IA-LPDs and other EBV-driven diseases, in both the U.S. and EU. We continue to enroll patients in this study. We are investigating additional label expansion opportunities with our Phase 2 multi-cohort study. In December 2023, we presented combined analysis that included the first reported data from our Phase 2 multi-cohort study at the European Society for Medical Oncology Immuno-Oncology annual congress that demonstrated a 77.8% ORR in 18 CNS EBV+ PTLD patients including first line PTLD.

ATA3219

We are developing ATA3219, an allogeneic CD19 CAR T immunotherapy targeting B-cell malignancies and autoimmune diseases, leveraging our next-generation 1XX CAR co-stimulatory domain and EBV T-cell platform and does not require TCR or HLA gene editing. ATA3219 combines the natural biology of unedited T cells with the benefits of an allogeneic therapy. It consists of allogeneic EBV-sensitized T cells that express a CD19 CAR construct for the treatment of CD19+ r/rB-cell malignancies, including B-cell non-Hodgkin’s lymphoma (NHL) and B-cell mediated autoimmune diseases including systemic lupus erythematosus (SLE) with kidney involvement (lupus nephritis (LN)). ATA3219 has been optimized to offer a potential best-in-class profile, featuring off-the-shelf availability. It incorporates multiple clinically validated technologies including a modified CD3ζ signaling domain (1XX) that optimizes expansion and mitigates exhaustion, provides enrichment during manufacturing for a less differentiated phenotype for robust expansion and persistence and retains the endogenous T-cell receptor without gene editing as a key survival signal for T cells which contribute to persistence.

Data from preclinical studies for ATA3219 suggest enhanced functional persistence, polyfunctional phenotype and efficient targeting of CD19-expressing tumor cells both in vitro and in vivo with a manufacturing process that focuses on T-cell stemness. Additional in vitro data demonstrate the CD19 antigen-specific functional activity of ATA3219 and CAR-mediated activity against B cells from SLE patients, leading to robust CD19-specific B-cell depletion compared to controls. This preclinical data was submitted as part of a late-breaking abstract which was accepted for poster presentation at the upcoming International Society for Cell & Gene Therapy meeting to be held May 29-June 1, 2024.

Based on academic data from a clinical study, an EBV T-cell platform has the potential to generate off-the-shelf, allogeneic CAR T immunotherapies with EBV+ PTLD following HCT who have failed rituximab. PRIME provides early enhanced regulatory supporthigh response rates, durable responses and low risk of toxicity that can be rapidly delivered to facilitate regulatory applicationspatients.

Our EBV CD19 CAR T program incorporates multiple clinically validated technologies designed for a memory phenotype, robust expansion, and accelerateretains the reviewendogenous T-cell receptor without gene editing as a key survival signal for T cells contributing to functional persistence. We continue to make progress on the ATA3219 manufacturing process for scale-up.

Data from an academic study (Curran et al ASH 2023) that used allogeneic EBV CAR T cells (CD28/CD3ζ co-stimulatory domain), demonstrated proof of medicinesprinciple for Atara’s allogeneic CAR T approach with overall survival up to 3 years in post-transplant B-cell malignancy patients. Atara’s ATA3219 builds upon this study with an improved process and construct that addressleverages multiple clinically validated technologies featuring a high unmet need. less differentiated phenotype and a novel 1XX costimulatory domain. We continue to make progress on the ATA3219 manufacturing process for scale-up.

In January 2017,July 2023, we received parallel scientific advicea Safe to Proceed letter from the EMA’s Scientific Advice Working Group and several national Health Technology Assessment agenciesFDA in response to our IND submission for ATA3219 in r/r B-cell NHL. We initiated enrollment of a multi-center, Phase 1 open-label, dose escalation clinical trial for ATA3219 in NHL, including large B-cell lymphomas, follicular lymphoma, or mantle cell lymphoma, with initial clinical data anticipated in the EU, including thosefourth quarter of 2024.

In February 2024, we received a Safe to Proceed letter from the FDA in the United Kingdom, Germany and France. Based on these discussions, we planresponse to submit an applicationour IND submission for Conditional Marketing Authorization, or CMA,use of tabelecleucel inATA3219 as a monotherapy for the treatment of patientsSLE with EBV+ PTLD following HCT who have failed rituximabLN and expect to initiate a Phase 1 study to evaluate the safety and preliminary efficacy of ATA3219 in the second half of 2024. Initial data is anticipated in the first half of 2019. The CMA will be based on clinical2025.

Additional Programs and Platform Expansion Activities

In addition to the prioritized programs described above, we have a number of preclinical programs.

Our CAR T immunotherapy pipeline includes ATA3431, an allogeneic, bispecific CAR directed against CD19 and CD20 for B-cell malignancies and autoimmune disease, leveraging our 1XX CAR co-stimulatory domain and EBV T-cell platform and does not require gene TCR or HLA gene editing. ATA3431 is enriched for central memory CAR T cells and in December 2023, we presented preclinical data from Phase 1that demonstrated early evidence of antitumor activity, long-term persistence, and 2 trials conducted at MSK and supported by available data from our Phase 3 MATCH and ALLELE trials in patients with EBV+ PTLD after HCT and SOT who have failed rituximab, which will be ongoingsuperior tumor growth inhibition compared to an autologous CD19/CD20 CAR T benchmark at the time65th American Society of filing.

In 2017, we began pre-commercial preparation to support the planned tabelecleucel EU CMA submission. For example, we are developing a proprietary, web-based, off-the-shelf delivery solution for commercial use that we call Atara MatchMe™. The Atara MatchMe system will be a portal for health care professionalsHematology Annual Meeting and institutions that allows for order input including the provision of required patient HLA and other information, the execution of our cell selection algorithm, product shipment and tracking, as well as the capture of data on outcomes following treatment. In the first quarter of 2017, we also signed a lease for an approximately 90,580 square foot facility in Thousand Oaks, California.Exposition 2023. We are building out a multi-product cellular therapy manufacturing facility with operations expected to commence in 2018. Overall, we believe that tabelecleucel monotherapy has a compelling value proposition in the treatment of patients with EBV+ PTLD who have failed rituximab. Weprogressing toward an IND submission and expect to pursue approvals globallyfile an IND submission for tabelecleucelATA3431 in patients2025.

We are also collaborating with EBV+ PTLD following HCT and SOT who have failed rituximab and may seek partnersQIMR Berghofer to aid in our commercializationdevelop a potential next generation EBV vaccine which is differentiated from earlier EBV vaccine efforts in select markets. In addition, we expectthat solely focused on B cell responses to pursue development of tabelecleucel in earlier lines of therapy, including first line EBV+ PTLD in combination with rituximab.

Tabelecleucel for nasopharyngeal carcinoma, or NPC

NPC, is a type of head and neck cancer that is primarily EBV associated. Standard treatment for NPC includes radiation therapy with or without platinum-based chemotherapy. InEBV. We also retain the setting of metastatic disease after the failure of chemotherapy, median survival is approximately fiverights to 11 months based on historical data, and there are no approved therapeutic agents available to treat this disease today. Based on our market research, we estimate that in 2015 there were approximately 9,400 patients with metastatic or recurrent Type III NPC in the United States, the United Kingdom, France, Germany, Italy and Spain and approximately 93,000 in Asia. Treatment with tabelecleucel as a monotherapy has been evaluated in 14 patients with metastatic NPC after failure of one to three lines of chemotherapy in the studies conducted by MSKCC. An ORR of 21% was observed in these patients with one complete response and two partial responses. In addition, 11 of the 14 patients were alive at a median follow up of 18 months with a Kaplan-

Meier survival estimate of 84% at two years. Tabelecleucel was administered to this immune competent patient population without prior lymphodepleting chemotherapy. Additionally, evidence of T-cell expansion following administration was observed. In April 2017, we entered intoATA188, an agreement with Merck (known as MSD outside of the United States and Canada) to provide drug supply for a trial sponsored and conducted by us to evaluate tabelecleucel in combination with Merck’s anti-PD-1 (programmed death receptor-1) therapy, KEYTRUDA ® (pembrolizumab), in patients with platinum-resistant or recurrent EBV-associated NPC. The Phase 1/2 trial will evaluate the safety, pharmacokinetics, pharmacodynamics, and preliminary efficacy of the combination and is planned for initiation in the second half of 2018.

Other T-Cell Programs

ATA188 and ATA190 for multiple sclerosis

MS is a chronic disorder of the central nervous system, or CNS, that disrupts the myelination and normal functioning of the brain, optic nerves and spinal cord through inflammation and tissue loss. The evolution of MS results in an increasing loss of both physical and cognitive (e.g., memory) function. This has a substantial negative impact on the approximately 2.3 million people worldwide affected by MS.

There are two categories of MS: progressive MS, or PMS; and relapsing-remitting MS, or RRMS. PMS is a severe form of MS with few therapeutic options. Within PMS there are two types of MS: secondary progressive MS, or SPMS; and primary progressive MS, or PPMS. According to the National Multiple Sclerosis Society, there are approximately one million people affected by PMS. Both types of PMS are characterized by persistent progression and worsening of MS symptoms and physical disability over time. PPMS occurs when the patient has a disease course characterized by steady and progressive worsening after disease onset. SPMS initially begins as RRMS, but once patients have continuous progression of their disease, they have developed SPMS. This is distinct from RRMS, where patients have flares of the disease that are followed by periods of recovery and quiescence during which the disease does not progress. There is substantial unmet medical need for new and effective therapies for patients with PMS. Most of the treatment options that work well in reducing the flares in RRMS have not been shown to be effective in slowing or reversing the progression of disability in PMS. The two approved therapeutic options for PMS patients have a modest impact on symptoms and disease progression and, therefore, we believe that unmet need remains. In the United States, mitoxantrone is approved for SPMS and ocrelizumab was approved in March 2017 for PPMS. Siponimod is currently being studied in Phase 3 trials for SPMS.

There is a strong biologic connection between EBV and MS. EBV is present in nearly all patients with MS. For example, in an international study of patients with clinically isolated syndrome, a CNS demyelinating event isolated in time that is compatible with the possible future development of MS, only one patient out of 1,407 was seronegative for, or not infected with, EBV. In addition, in separate studies, clusters of EBV infected B-cells and plasma cells were evident in the brains of MS patients but not found in brains of patients without MS. In these studies, the EBV infected B-cells and plasma cells were in close proximity to areas of active demyelination. Studies suggest that EBV positive B-cells and plasma cells in the CNS have the potential to catalyze an autoimmune response and the MS pathophysiology. In patients with MS, their T-cells may be unable to control EBV positive B-cells and plasma cells so that B-cells and plasma cells could then accumulate in the brain and generate antibodies that attack and destroy myelin, the protective layer that insulates nerves in the brain and spinal cord. This loss of myelin ultimately leads to MS symptoms. MS disease course has also been shown to correlate with measures of EBV activity. The role of B-cells in MS is supported by the recent approval by the FDA of ocrelizumab for PPMS which broadly targets B-cells through their expression of a cell surface marker known as CD20. Low vitamin D also suppresses T-cells and is associated with MS.

Our secondallogeneic T-cell immunotherapy product candidate, ATA188, is an off-the-shelf EBV-specific T-cell that utilizes a targeted antigen recognition technology that enables the T-cells we administer to selectively identify cells expressing thetargeting EBV antigens that we believe arebelieved to be important for the potential treatment of MS.multiple sclerosis (MS). We arehave paused development on ATA188 while we explore strategic options for this asset. We have also developing an autologous version of this product candidatediscontinued some programs and will return the programs to our collaborators. For example, in February 2024, we notified MSK that we call ATA190. ATA190 utilizeswill return the same approachATA2271 and ATA3271 programs targeting mesothelin to targeted antigen recognition as ATA188. These product candidates are designed to selectively target only those cells which are EBV positive while sparing those that are not. We believe that eliminating only EBV positive B-cells, including plasma cells, has the potential to benefit some patients with MS through enhanced efficacy and a better side-effect profile. In October 2015, we obtained an exclusive, worldwide license to develop and commercialize allogeneic T-cell immunotherapy product candidates targeting EBV, including ATA188, utilizing technology and know-how developed by QIMR Berghofer. In connection with this license, we also received an option to exclusively license the autologous version of EBV product candidates, including ATA190.MSK.

In the fourth quarter of 2017, we initiated an open label, single arm, multi-center, multi-national Phase 1 trial with allogeneic ATA188 for patients with MS and in January 2018 received clearance of our investigational new drug, or IND, application from the FDA to proceed with patient enrollment at U.S. sites.  The primary objective of this Phase 1 trial is to assess the safety of ATA188 in patients followed for at least one year after the first dose. Key secondary endpoints in the trial include measures of clinical improvement such as Expanded Disability Status Scale, or EDSS, and annualized relapse rate, or ARR, as well as MRI imaging. The trial is expected to enroll a total of 60 patients across the United States, Australia and Europe: 30 patients with PMS, either PPMS or SPMS, and 30 patients with RRMS. We expect to announce results from our ATA188 Phase 1 trial in patients with PMS in the first half of 2019.

In addition, based on the Phase 1 clinical results observed to date with ATA190, we believe the continued development of ATA190 will enhance our understanding of the potential therapeutic utility of targeting EBV in the treatment of MS and further inform and complement our development of ATA188, and we are planning a multicenter Phase 1/2 trial with ATA190 in PMS.

Our collaborating investigators at QIMR Berghofer are currently conducting a Phase 1 trial utilizing autologous ATA190 for the treatment of patients with PMS. We believe this is the first clinical trial to prospectively explore both the feasibility and potential utility of targeting EBV in MS. The trial is designed to:

Each patient receives four escalating doses of ATA190 over six weeks, with each individual dose given once every two weeks. Patients are followed for 20 weeks after the last dose. An abstract from our collaborating investigators describing interim results from this Phase 1 trial was selected for inclusion in the Emerging Science Program during the 69th American Academy of Neurology Annual Meeting in April 2017 and updated interim results for all ten patients were recently presented at the MSParis 2017 Congress, the 7th Joint Meeting of the European Committee for Treatment and Research in Multiple Sclerosis and the Americas Committee for Treatment and Research in Multiple Sclerosis.

Results presented include data on five SPMS patients and five PPMS patients. Clinical improvements were reported in six of the ten patients treated and these improvements were observed within two to fourteen weeks after the first dose. Three patients improved their EDSS score. EDSS is a method for quantifying disability and monitoring changes over time. Reduction in fatigue was a consistent observation in responding patients. Five of the six patients who showed clinical improvements received ATA190 with greater than or equal to 7% EBV reactivity, or T-cell reactivity against target EBV antigens following manufacturing. This suggests that EBV reactivity may be an important product characterization metric for future development. ATA190 was well-tolerated, and no significant treatment-related adverse events were observed. A summary of study results is highlighted in the table below.

Overall, we believe these results are encouraging and support the continued development of ATA188 and ATA190 in MS.

ATA520 for hematologic malignancies

Our third T-cell immunotherapy product candidate, ATA520, is an off-the-shelf  WT1 specific T-cell immunotherapy, that targets cancers expressing the antigen WT1 and is currently in Phase 1 clinical trials. WT1 is an intracellular protein that is overexpressed in a number of cancers, including hematological malignances as well as solid tumors. MSK has two Phase 1 clinical trials evaluating ATA520. The first trial is a dose escalation trial of ATA520 for residual or relapsed leukemia after HCT. The second trial is a dose escalation trial of ATA520 following T-cell depleted HCT for patients with relapsed or refractory multiple myeloma, including plasma cell leukemia, or PCL. Based on data from these trials, we intend to develop ATA520 in a select set of hematologic malignancies and solid tumors. Given the advances of our EBV-related pipeline programs in NPC and MS, as well as the opportunity to pursue a conditional marketing authorization in the EU for tabelecleucel, we expect to initiate an additional clinical trial with

ATA520 following the further process development of ATA520 as well as the clinical and regulatory advancement of tabelecleucel and ATA188.

ATA230 for CMV viremia and disease

Our fourth T-cell immunotherapy product candidate, ATA230, is an off-the-shelf CMV specific T-cell immunotherapy, that is in Phase 2 clinical trials for refractory CMV infection that occurs in some patients who have received an HCT or SOT or are otherwise immunocompromised. We met with the FDA for an end of Phase 2 meeting to discuss late stage development of ATA230 for the treatment of anti-viral refractory or resistant CMV infection following either HCT or SOT. Our collaborating investigators presented updated ATA230 results from 50 post-transplant patients with refractory CMV viremia and disease, including those with disease in the central nervous system, at the 59th ASH Annual Meeting in Atlanta, Georgia, in December 2017. Results reported include a response rate of approximately 60% in all patients, which was similar in those with CMV viremia and disease. Patients who responded to ATA230 showed improved 6- and 12-month survival rates of approximately 80% and 60%, respectively, versus those patients who did not respond to treatment. One of the 32 patients who responded died of CMV disease. ATA230 was generally well tolerated. Five patients experienced grade 4 or higher adverse events deemed possibility related to ATA230. Recently, the FDA granted orphan drug designation for ATA230 for the treatment of CMV viremia and disease in immunocompromised patients as well as Rare Pediatric Disease Designation for the treatment of congenital CMV infection. The EMA has also granted us orphan status for ATA230 for CMV infection in patients with impaired cell-mediated immunity. Given the opportunity to pursue a CMA in the EU for tabelecleucel, we have decided to prioritize our EBV related programs ahead of ATA230 at this time, and plan to further evaluate our development strategy for ATA230 in 2018.

ATA621 for BK and JC virus associated diseases

Through our ongoing collaboration with QIMR Berghofer, we recently developed a new T-cell immunotherapy product candidate, ATA621, for BK and JC virus associated diseases. These two viruses are closely related and there are no available antiviral agents approved for use in BK or JC associated diseases. JC virus is associated with progressive multifocal leukoencephalopathy, or PML, which occurs in transplant, HIV and cancer patients as well as in patients treated with other immunosuppressive therapies, including certain therapies utilized for the treatment of MS. Based on our market research, we estimate that there are approximately 7,800 cases of PML annually, worldwide. BK virus is associated with hemorrhagic cystitis, or BKVHC, which mainly occurs following HCT or cyclophosphamide treatment as well as BK virus associated nephropathy, or BKVAN, which is a disease most commonly associated with kidney transplant. Based on Atara market research, we estimate that there are approximately 2,100 cases of BKVAN and 2,300 cases of BKVHC annually, worldwide. We are currently conducting investigational new drug application enabling manufacturing process development and plan to initiate a Phase 1 trial with ATA621 in 2019.

Our pipeline of product candidates is highlighted in the figure below.

Additional Platform Expansion Activities

We believe our T-cell technology platform will have utility beyond the current set of targets to which it has been directed. We expectcontinue to further research and developevaluate additional cellular therapies, which may include T-cell programs targeted against other antigens as well as engineered T-cell immunotherapies such as chimeric antigen receptor, or CAR-T, cell programs. We believe that viral antigens are well suited to adoptive immunotherapy given that peopleproduct candidates, including those derived from collaborations with normal immune systems are able to mount robust responses to these viral targets, but immunocompromised patients and some cancer patients are not.our partners. We also intendcontinue to evaluate opportunities to license or acquire additional product candidates or technologies to enhance our existing T-cell technology platform.

Competition

The biotechnology and pharmaceutical industries are characterized by rapidly advancing technologies, intense competition and a strong emphasis on proprietary products. While we believe that our innovative technology, knowledge, experience and scientific resources provide us with competitive advantages, weWe face potential competition from many different sources, including major pharmaceutical, specialtynumerous pharmaceutical and biotechnology companies,enterprises, as well as from academic institutions, government agencies and private and public and private research institutions.institutions for our current product candidates. Some of these competitors or potential competitors may have a moresignificantly greater established presencepresences in the market, financial resources, varied technologies, scientific tools and significantly greater financial, technical and human resourcesexpertise than we have.do. Our commercial opportunityopportunities will be reduced or eliminated if our competitors develop and commercialize products that are safer, more effective, have fewer side effects or are less expensive than any products that we may develop.

T-Cell Product Candidates

Should any of our T-cell product candidates be approved for use, we will face substantial competition. In addition to the current standard of care for patients, commercial and academic clinical trialsstudies are being pursued by a number of parties in the field of immunotherapy. Early results from these trialsstudies have fueled continued interest in T-cell immunotherapy. In addition, if approved, our T-cell programs would compete with currently marketed drugs and therapies used for treatment of the following indications we are addressing, and potentially with drugproduct candidates currently in development for the same indications.

EBV+ PTLD

There are currently no FDA or EMA approvedFDA-approved products for the treatment of EBV+ PTLD.PTLD, and there are no EC-approved products for this indication except for Ebvallo. However, we are aware that some approvedmarketed products and therapies are currently used off-label in this setting. Companiesby some healthcare professionals and academic institutions that may license therapies to companies in the future are or may be developing new treatments. These therapies, as well as promotional efforts by competitors and clinical trial results of competitive products, could diminish the ability to market and sell tabelecleucel. The current treatment for EBV+ PTLD involves administration of rituximab as a single agent or in the SOT setting, in combination with chemotherapy regimens. Additionally, companies and academic institutions are developing drug candidates for EBV+ PTLD and other EBV associated diseases, including Cell Medica Ltd., or Cell Medica, which is conducting Phase 1 clinical trials for baltaleucel-T, an autologous EBV specific T-cell therapy in post-transplant lymphoproliferative disorder and Viracta Therapeutics, Inc., or Viracta, which has initiated Phase 1b/2 clinical trials for VRx-3996 in relapsed/refractory EBV⁺lymphomas.

Multiple Sclerosis

Competition in the MS market is high with fourteen therapies approved for the treatment of RRMS in the United States and European Union.  There are many U.S. and international competitors in the RRMS market, including major multi-national fully-integrated pharmaceutical companies and established biotechnology companies.  Most recently, Ocrevus^®, marketed by F. Hoffmann-La Roche, was approved for the treatment of relapsing MS in the United States and European Union.  There are numerous other development candidates in Phase 3 trials for RRMS including Novartis’ anti-CD20 monoclonal antibody ofatumumab; Alkermes’ monomethyl fumarate prodrug ALKS 8700; Teva’s laquinimod, and Actelion’s next-generation sphingosine 1-phosphate receptor, or S1PR, agonist ponesimod.  Celgene recently reported positive results from Phase 3 clinical trials evaluating ozamimod, a S1PR agonist, in relapsing MS.

Only three therapies have been approved for the treatment of progressive MS.  Recently, Ocrevus^® was approved in the United States and European Union for the treatment of PPMS.  Extavia^® (marketed by Novartis) is approved in the United States and European Union for the treatment of SPMS.  Betaseron^® (marketed by Bayer AG) is also approved in the European Union. Few therapies have been approved for progressive MS because many candidates have failed during clinical trial testing.  In the United States, there is one drug (mitoxantrone) approved to treat SPMS.  

The SPMS and PPMS markets have active development pipelines and additional novel agents could be approved in the future.  Several development candidates are being evaluated in clinical trials including a number of Phase 3 programs: MedDay SA is evaluating MD-1003, a concentrated form of biotin, for progressive MS; AB Science is evaluating masitinib, a tyrosine kinase inhibitor, for progressive MS; and Novartis is evaluating siponimod, an S1P1 modulator, for SPMS; and Actelion Pharmaceuticals is evaluating ponesimod, for SPMS.  

Multiple Myeloma including Plasma Cell Leukemia

Several products are approved for the treatment of relapsed or refractory multiple myeloma, or MM, including immunomodulatory drugs, or IMIDs,EBV+ PTLD, such as Thalomid^® (Celgene Corporation), Revlimid^® (Celgene Corporation)rituximab and Pomalyst^® (Celgene Corporation); monoclonal antibodies such as Darzalex^® (Janssen Research & Development, LLC) and Empliciti^® (Bristol Myers Squibb); and proteasome inhibitors such as Velcade^® (Millennium Pharmaceuticals, Inc.) and Kyprolis^® (Amgen Inc.).

A number of companies and institutions are pursuing development programs for relapsed or refractory MM.  These development programs include drug candidates being evaluated in clinical trials as a monotherapy or in combination with other approved agents.  chemotherapy regimens.

In addition, many groups are developing novel T-cell therapies such as autologous CAR T-cell or autologous TCR T-cell candidates.  These include bluebird bio, Inc., which is conducting Phase 2 clinical trials testing bb2121, an anti-BCMA CART; Gilead Sciences, Inc., which is testing KTE-585, an anti-BCMA CART in Phase 1 clinical trials; Juno Therapeutics, which is testing an anti-BCMA CART in Phase 1 clinical trials; Autolus Limited, which is testing AUTO-2, a bi-specific anti-BCMA/TACI CART in Phase 1 clinical trials and Adaptimmune Therapeutics PLC, which is testing an anti-NY-ESO TCR in Phase 1/2 clinical trials.

CMV Infection

There are numerous approved products and therapies for the treatment of CMV infection, and a number of companies and academic institutions that may license therapies to companies in the future are or may be developing new treatments for CMV infection. These therapies, as well as promotional efforts by competitors and clinical trial results of competitive products, could significantly diminish any ability to market and sell the CMV T-cell immunotherapy. Drug therapies approved or commonly used for CMV infection include antiviral compounds such as Prevymis®, marketed by Merck & Co. Inc.; ganciclovir, valganciclovir, cidofovir or foscarnet.

Additionally, a number of companies and academic institutions are developing drugproduct candidates for CMV infectionEBV+ PTLD and other CMV-associatedEBV-driven diseases including Shire Plcincluding: Viracta Therapeutics, Inc., which is conducting a pivotal, Phase 2 clinical study for nanatinostat (formerly named tractinostat, or VRx-3996) in combination with antiviral drug valganciclovir in relapsed/refractory EBV+ lymphomas; AlloVir (formerly known as ViraCyte), which has completed a Phase 2 clinical study for posoleucel (ALVR105), an allogeneic, multi-virus T-cell product that targets six viruses in allogeneic HSCT recipients with ≥1 treatment-refractory infection, including EBV, and is conducting two Phase 3 clinical trials of maribavir,for Virus-Associated Hemorrhagic-Cystitis, as well as a UL97 protein kinase inhibitor; Vical Inc., recently announced ASP0113, a therapeutic bivalent plasma DNA CMV vaccine being evaluated in patients undergoing an allogeneic stem cell transplant, failed to meet primary or secondary endpoints in Phase 3 trial for the prevention of BKV, CMV, AdV, EBV, HHV06 and JCV in post-allogeneic HSCT patients.

CAR T Program

There are currently six autologous CAR T therapies approved in the U.S. and/or EU: Novartis’ Kymriah® (tisagenlecleucel), Gilead/Kite’s Yescarta® (axicabtagene ciloleucel) and TecartusTM (brexucabtagene autoleucel) and Bristol-Myers Squibb’s Breyanzi® (lisocabtagene maraleucel) and Abecma (idecabtagene vicleucel) with 2seventy bio and Johnson & Johnson and Legend Biotech’s Carykti™ (ciltacabtagene autoleucel). There are many CAR-mediated cell therapies in development, and, although the majority are autologous, they also include allogeneic and off-the-shelf cell therapies. There are multiple allogeneic CAR platforms being developed with differences in approaches to minimize instances of donor cells recognizing the patient’s body as foreign or rejection of the donor cells by the patient’s body. These approaches include the use of gene-editing to remove or inhibit the TCR and the use of cell types without a TCR. The majority of clinical trials.stage allogeneic CAR programs utilize alpha beta T cells as the cell type and gene editing of the T-cell receptor and HLA as the preferred technology approach, however, other strategies are also in development. It is possible that some of these other approaches will have more favorable characteristics than the approach we utilize, which would result in them being favored by potential partners or customers over our products. Depending on the diseases (such as autoimmune diseases) that we target in the future, we may face competition from both autologous and allogeneic CAR therapies and other modalities (e.g., small molecules, antibodies, bispecifics) in the indication of interest.

Terms of Certain License and Collaboration Agreements

Out-licensing

Pierre Fabre Commercialization Agreement

In October 2021, we entered into the Pierre Fabre Commercialization Agreement, pursuant to which we granted to Pierre Fabre an exclusive, field-limited license to commercialize and distribute Ebvallo in Europe and select emerging markets in the Initial Territory following regulatory approval. In September 2022, we amended the Pierre Fabre Commercialization Agreement and received an additional $30 million milestone payment from Pierre Fabre following EC approval of Ebvallo for EBV+ PTLD and subsequent filing of the MAA transfer to Pierre Fabre, in exchange for, among other things, a reduction in: (i) royalties we are eligible to receive as a percentage of net sales of Ebvallo in the Initial Territory, and (ii) the supply price mark up on Ebvallo purchased by Pierre Fabre. Additionally, we agreed to extend the time period for provision of certain services to Pierre Fabre under the Pierre Fabre Commercialization Agreement. In December 2022, we sold a portion of our right to receive royalties and certain milestones in Ebvallo under the Pierre Fabre Commercialization Agreement to HCRx for a total investment amount of $31.0 million, subject to a repayment cap between 185% and 250% of the total investment amount by HCRx. See Note 6 – “Liability Related to the Sale of Future Revenues” in the Notes to Consolidated Financial Statements, included in Item 8. Financial Statement and Supplementary Data of this report for further information related to the agreement with HCRx.

In October 2023, we entered into an A&R Commercialization Agreement, pursuant to which we expanded Pierre Fabre’s exclusive rights to research, develop, manufacture, commercialize and distribute Ebvallo to include the Additional Territory in addition to the Initial Territory, subject to our performance of certain obligations as described below.

During the applicable period specified in the A&R Commercialization Agreement, we will be responsible, at Pierre Fabre’s cost, to continue conducting the ongoing Phase 3 ALLELE clinical study and the Phase 2 multi-cohort clinical study. We will also be responsible, at Pierre Fabre’s cost, for certain other activities directed to obtaining regulatory approval in the United States for tab-cel for EBV-associated post-transplant lymphoproliferative disease pursuant to the terms of the A&R Commercialization Agreement. Pierre Fabre will be responsible, at its cost, for obtaining and maintaining all other required regulatory approvals and for commercialization and distribution of tab-cel in the Additional Territory, including conducting any other clinical study required. We will own any intellectual property rights developed solely by us under the Agreement.

As part of the Pierre Fabre Commercialization Agreement, we formed a joint steering committee (JSC) with Pierre Fabre that provides oversight, decision making and implementation guidance regarding the commercialization activities, the responsibilities of which has been expanded to cover the incremental scope of the A&R Commercialization Agreement.

We are also responsible for cell selection services in the Initial Territory at our cost for a CMV MVA-vaccinecertain period of time, unless the parties agree to transfer the related cell selection technology to Pierre Fabre prior to this date, and we are responsible for cell selection services at the sole expense of Pierre Fabre for a CMV peptide vaccinecertain period of time in patients undergoing an allogeneic hematopoietic stemthe Additional Territory. After this period of time, if we agree to continue to provide cell transplant;Merckselection services in the Territory, it shall be at the sole expense of Pierre Fabre. Cell selection is conducting Phase 1 clinical trialsthe process of identifying the appropriate cell line from available inventory to be used for V160, a CMV DNA vaccine; VBI Vaccines Inc., has completed Phase 1 clinical trials for VBI-1501A, an eVLP vaccine; Hookipa Biotech, is conducting Phase 1 clinical trials for HB101, a bivalent vaccine, ViraCyte, is conducting Phase 1 clinical trials for Viralym-C, a CMV-specific allogeneicpatient. Without transfer of the cell therapy product; Fate Therapeutics is conducting a Phase 1/2 clinical trial for ProTmune, a small molecule programmed mobilized peripheral blood graft; Chimerix is conducting Phase 1 clinical trials for intravenous Brincidofovir (BCV IV), a nucleotide analog and Moderna Therapeutics is conducting Phase 1 clinical trials for mRNA-1647, an mRNA based prophylactic vaccine.selection technology, no other party can provide such services.

LicenseIn-licensing

MSK Agreements

MSK Option and License Agreement

In September 2014,June 2015, we entered into an exclusive optionlicense agreement with MSK under which we acquired the right to exclusively license from MSK the worldwide rights tofor three clinical stage T-cell programs. The initial option period was for 12 months. In exchange for the exclusive option, we paid MSK $1.25 million in cash and issued 59,761 shares of our common stocktherapies. We are required to MSK. We and MSK also agreed to collaborate on further research to develop additional cellular therapies, which may include T-cell programs targeted against other antigens and/or CAR-T, and which we also would hold an option to license, if developed.

In June 2015, we exercised the option and entered into a license agreement with MSK. Under the terms of the license agreement, MSK granted us a worldwide, exclusive license under certain patent rights, know-how and a library of T-cells and cell lines, to research, develop, manufacture and commercialize T-cell products specific to CMV, EBV or WT1 that comprise or are based on or made using such licensed rights. MSK also agreed to transfer certain INDs related to the licensed products to us. We have agreed to use commercially reasonable efforts to commercialize the licensed products and, if commercialized, continue active marketing efforts for any commercialized licensed product through the term of the license agreement.

In connection with the option exercise and the execution of the license agreement, we made an upfront cash paymentmake payments to MSK of $4.5 million. We are obligated to make additional milestone payments of up to $33.0 million with respect to the three licensed clinical stage T-cell programs based on achievement of specified development, regulatory and sales-related milestones. We are also required to make escalating mid to high single-digitmilestones, as well as mid-single-digit percentage tiered royalty payments to MSK based on future sales of anyproducts resulting from the development of the licensed products.product candidates, if any. In addition, under certain circumstances, we mustare required to make certain minimum annual royalty payments to MSK, which are creditable against earned royalties owed for the same annual period. We are also obligatedrequired to pay a low double-digit percentage of any consideration we receive for sublicensing the licensed rights.

The license agreement expires for each licensed T-cell product on a licensed product-by-licensed product basisproduct-by-product and a country-by-country basis on the latest of: (i) expiration of the last licensed patent rights related to sucheach licensed product, in such country, (ii) expiration of any market exclusivity period granted by law with respect to sucheach licensed product, in such country, and (iii) a specified number of years after the first commercial sale of the licensed product in sucheach country. Upon expiration of the license agreement, we will retain non-exclusive rights to the licensed products.

In May and December 2018, we licensed additional technology from MSK. We are obligated to make additional milestone payments based on achievement of specified development, regulatory and sales-related milestones, as well as mid-single-digit percentage tiered royalty payments based on future sales of products resulting from the development of the licensed product candidates, if any.

In March 2021, we amended and restated our license agreement with MSK to terminate our license to certain rights and license additional know-how rights not otherwise covered by our existing agreements.

In February 2024, we notified MSK that we intend to terminate our licenses granted to us will become non-exclusive royalty-free, perpetualthe ATA2271 and irrevocable. MSK may terminateATA3271 programs targeting mesothelin.

QIMR Berghofer Agreements

In October 2015, we entered into an exclusive license agreement and a research and development collaboration agreement with QIMR Berghofer. Under the terms of the license agreement, if we materially breachobtained an exclusive, worldwide license to develop and commercialize allogeneic T-cell therapy programs utilizing technology and know-how developed by QIMR Berghofer. In September 2016, the exclusive license agreement and does not cure such breach within a specified period orresearch and development collaboration agreement were amended and restated. Under the amended and restated agreements, we obtained an exclusive and worldwide license to develop and commercialize additional T-cell programs, as well as the option to license additional technology in June 2018. We further amended and restated our license agreement and research and development collaboration agreements with QIMR Berghofer in August 2019 to terminate our license to certain rights related to cytomegalovirus (CMV). In addition, we further amended and restated our license agreement and research and development collaboration agreements with QIMR Berghofer in August 2020 to terminate our license to certain rights related to BK polyomavirus and JC polyomavirus. In December 2021, we further amended and restated our license agreement and research and development collaboration agreements with QIMR Berghofer to terminate our license to certain rights related to HPV associated cancers. We refer to our December 2021 fourth amended and restated license agreement with QIMR Berghofer as the QIMR License Agreement and our December 2021 fourth amended and restated research and development collaboration agreement with QIMR Berghofer as our QIMR Collaboration Agreement.

The QIMR License Agreement provides for various milestone and low to mid single-digit royalty payments to QIMR Berghofer based on future product sales, if any. Under the terms of the QIMR Collaboration Agreement, we experienceare required to reimburse the cost of agreed-upon development activities related to programs developed under the collaboration. The QIMR Collaboration Agreement also provides for various milestone payments to QIMR Berghofer based on the achievement of certain insolvency events.developmental and regulatory milestones.

Intellectual Property

Patents

Our commercial success depends in part on our ability to obtain and maintain proprietary protection for our product candidates, to operate without infringing on the proprietary rights of others and to prevent others from infringing our proprietary rights. Our policy is toWe seek to protect our proprietary position by, among other methods, filing U.S. and non-U.S. patent applications and other regulatory filings related to our proprietary technology, inventions and improvements that are important to the development and implementation of our business. We also rely on trademarks, trade secrets, know-how, continuing technological innovation and potential in-licensing opportunities to develop and maintain our proprietary position. Some of patents, trademarks, trade secrets, know-how and other intellectual property rights we rely on are owned by us and others are in-licensed from our partners. When we refer to “our” technologies, inventions, patents, patent applications or other intellectual property rights, we are referring to both the rights that we own or possess as well as those that we in-license. Additionally, we expect to benefit from a variety of statutory frameworks in the United States,U.S., Europe and other countries that relate to the regulation of biosimilar molecules and orphan drug status. These statutory frameworks provide certain periods of regulatory exclusivity for qualifying molecules. See “Government Regulation.”

Patents

We seek composition-of-matter and/or associated method patents, including method-of-treatment patents, for each of our product candidates in key therapeutic areas. The United StatesU.S. patent system permits the filing of provisional and non-provisional patent applications. A provisional patent application is not examined for patentability by the USPTOU.S. Patent and Trademark Office (USPTO), and automatically expires 12

months after its filing date. As a result, a provisional patent application cannot mature into an issued patent. Provisional patent applications are often used, among other things, to establish an early effective filing date for a later-filed non-provisional patent application. A non-provisional patent application is examined by the USPTO and can mature into a patent once the USPTO determines that the claimed invention meets the standards of patentability.

Individual patents extend for varying periods of time depending on the date of filing of the patent application, the priority date claimed, and the legal term of patents as determined by the applicable law in the countries in which those patents are obtained. Generally, patents issued from applications filed in the United StatesU.S. are effective for 20 years from the earliest non-provisional filing date. In addition, in certain instances, a patent term can be extended to recapture a portion of the term effectively lost as a result of the FDA regulatory review period; however, the restoration period cannot be longer than five years and the total patent term including the restoration period must not exceed 14 years following FDA approval. Additionally, patent term adjustments can extend term to account for certain delays by the U.S. Patent and Trademark Office, or USPTO during prosecution before that office. The duration of non-U.S. patents varies in accordance with provisions of applicable local law, but typically, the life of a non-U.S. patent is 20 years from the earliest international filing date, not inclusive of any patent term extension that may be available. The actual protection afforded by a patent varies on a product-by-product basis, from country to country and depends upon many factors, including the type of patent, the scope of its coverage, the

availability of extensions of patent term, the availability of legal remedies in a particular country and the validity and enforceability of the patent.

National and international patent laws concerning protein-based biologics such as our products remain highly unsettled. No consistent policy regarding the patent-eligibility or the breadth of claims allowed in such patents in this field has emerged to date among the United States,U.S., Europe andor other countries. Changes in either the patent laws or in interpretations of patent laws in the United States andU.S. or other countries can diminish our ability to protect our inventions and enforce our intellectual property rights. Accordingly, we cannot predict the breadth or enforceability of claims that may be granted in our patents or in third-partythird party patents. The biotechnology and pharmaceutical industries are characterized by extensive intellectual property litigation. Our ability to maintain and solidify our proprietary position for our product candidates and technology will depend on our success in obtaining effective claims for any patentour patents and enforcing those claims once a patent is granted. We do not know whether any of theour patent applications that we may file or license from third parties will result in the issuance of any patents. TheOur issued patents that we own or may receive in the future may be challenged, invalidated or circumvented, and the rights granted under any issued patents may not provide us with sufficient protection or competitive advantages against competitors with similar technology. Furthermore, our competitors may independently develop and commercialize similar drugs or duplicate our technology, business model or strategy without infringing our patents. Because of the extensive time required for clinical development and regulatory review of any drug we may develop from our product candidates, it is possible that, before any of our drugs can be commercialized, any related patent may expire or remain in force for only a short period following commercialization, thereby reducing any advantage of any such patent. The patent positions for our product candidates are summarized below:

Our global patent estate consists of both issued patentssolely-owned and pending patent applications and includes wholly-owned patent applications, in-licensed patents and patent applications, to which we generally hold exclusive commercial rights, and patents and patent applications to which we hold an exclusive option to license commercial rights. Regarding our tabelecleucel for EBV+PTLD following HCT or SOT, tabelecleucel for NPC, ATA188, ATA190, ATA520, ATA230 and ATA621 programs, and our platform technologies underlying these programs, our global patent estate is directed to compositions of matter and/or associated methods, including methods of treatment, and consists of 2519 patent families having a total of 95more than 230 issued patents or patent applications. The issuedOur patents and patent applications (if issued) of our global patent estate are expected to expire between 20232024 and 2038,2044, not inclusive of any patent term extension that may be available isin any associated jurisdiction.

Trade Secrets

In addition to patents, we rely upon unpatented trade secrets and know-how and continuing technological innovation to develop and maintain our competitive position. We seek to protect our proprietary information, in part, using confidentiality agreements with our commercial partners, collaborators, employees and consultants and invention assignment agreements with our employees. These agreements are designed to protect our proprietary information and, in the case of the invention assignment agreements, to grant us ownership of technologies that are developed by an employee. These agreements may be breached, and we may not have adequate remedies for any such breach or any unauthorized disclosure of our proprietary information. In addition, our trade secrets may otherwise become known or be independently discovered by competitors. To the extent that our commercial partners, collaborators, employees and consultants use intellectual property owned by others in their work for us, disputes may arise as to the rights in related or resulting know-how and inventions.

Government Regulation

OverviewTrademarks

We also rely upon trademarks to develop and maintain our competitive position, and we continue to pursue and obtain trademark rights relating to our business. We have a vigorous global program of U.S. Government Regulation

The preclinical studiestrademark registration and clinical testing, manufacture, labeling, storage, recordkeeping, advertising, promotion, export, marketingenforcement to maintain and sales, among other things,strengthen the value of our product candidatestrademarks and prevent the unauthorized use of those trademarks. Our global trademark portfolio consists of six different trademark families comprised of more than 70 registrations and pending applications.

Government Regulation and Product Approval

As a biopharmaceutical company that operates in the United States, we are subject to extensive regulation by governmentalregulation. Our T-cell immunotherapies, if approved, will be products regulated as biological products, or biologics. With this classification, commercial production of our products will need to occur in registered facilities in compliance with current good manufacturing practice (cGMP) for biologics. The FDA categorizes human cell- or tissue-based products as either minimally manipulated or more than minimally manipulated and has determined that more than minimally manipulated products require clinical trials to demonstrate product safety and efficacy and the submission of a BLA for marketing authorization. Our product candidates are considered more than minimally manipulated and will require evaluation in clinical trials and the submission and approval of a BLA before we can market them.

Government authorities in the United States (at the federal, state and local level) and in other countries. Incountries extensively regulate, among other things, the United States, pharmaceuticalresearch, development, testing, manufacturing, quality control, approval, labeling, packaging, storage, record-keeping, promotion, advertising, distribution, tracking and tracing, post-approval monitoring and reporting, marketing and export and import of biopharmaceutical products such as those we are regulateddeveloping. Our product candidates must be approved by the FDA before they may be legally marketed in the U.S. and by the appropriate foreign regulatory agency before they may be legally marketed in foreign countries. Generally, our activities in other countries will be subject to regulation that is similar in nature and scope as that

imposed in the U.S., although there can be important differences. Additionally, some significant aspects of regulation in Europe are addressed in a centralized way, but country-specific regulation remains essential in many respects. The process for obtaining regulatory marketing approvals and the subsequent compliance with appropriate federal, state, local and foreign statutes and regulations require the expenditure of substantial time and financial resources.

U.S. Product Development Process

In the U.S., the FDA regulates pharmaceutical and biological products under the Federal Food, Drug and Cosmetic Act and other laws, including, in the case of biologics,(FDCA), the Public Health Service Act.

Our T-cell immunotherapy product candidates, including tabelecleucel (formerly known as ATA129)Act (PHSA), are regulated byand their implementing regulations. The process of obtaining regulatory approvals and the FDA as biologics, reviewed by the Center for Biological Evaluationsubsequent compliance with appropriate federal, state, local and Research,foreign statutes and willregulations require the submissionexpenditure of BLAssubstantial time and approval by the FDA prior to being marketed in the United States. For T-cell immunotherapy trials conducted at, or sponsored by, institutions receiving NIH funding for recombinant DNA research, prior to the submission of an IND to the FDA, a protocol and related documents must be submitted to, and the study registered with, the NIH Office of Biotechnology Activities, or the OBA, pursuant to the NIH Guidelines for Research Involving Recombinant DNA Molecules, or the NIH Guidelines. Compliance with the NIH Guidelines is mandatory for investigators at institutions receiving NIH funds for research involving recombinant DNA. However, many companies and other institutions, not otherwise subject to the NIH Guidelines, voluntarily follow them. The NIH is responsible for convening the recombinant DNA advisory committee, or RAC, that discusses protocols that raise novel or particularly important scientific, safety or ethical considerations at one of its quarterly public meetings. The OBA will notify the FDA of the RAC’s decision regarding the necessity for full public review of a protocol. RAC proceedings and reports are posted to the OBA website and may be accessed by the public.

financial resources. Failure to comply with FDAthe applicable U.S. requirements both before andat any time during the product development process, approval process or after product approval, may subject us or our partners, contract manufacturers, and suppliersan applicant to administrative or judicial sanctions. FDA sanctions including FDAcould include, among other actions, refusal to approve pending applications, withdrawal of an approval, a clinical hold, warning or other enforcement letters, product recalls or withdrawals from the market, product seizures, total or partial suspension of production or distribution injunctions, fines, and/refusals of government contracts, restitution, disgorgement or civil or criminal prosecution.

penalties. Any agency or judicial enforcement action could have a material adverse effect on us. The stepsprocess required by the FDA before a biologicbiological product may be approved for marketing of an indicationmarketed in the United StatesU.S. generally include:involves the following:

Before conducting studiestesting any biological product candidate, including our product candidates, in humans, the product candidate enters the preclinical testing stage. Preclinical tests, also referred to as nonclinical studies, include laboratory evaluationevaluations of product chemistry, toxicity and formulation, as well as animal studies to assess the potential safety and efficacyactivity of the biologic candidateproduct candidate. The conduct of the preclinical tests must be conducted. Preclinical toxicology studies in animalscomply with federal regulations and requirements including applicable GLPs. The clinical trial sponsor must be conducted in compliance with FDA regulations. Thesubmit the results of the preclinical tests, together with manufacturing information, and analytical data, are submittedany available clinical data or literature and a proposed clinical trial protocol, to the FDA as part of anthe IND. Some preclinical testing may continue even after the IND is submitted. In addition to including the results of the preclinical testing, the IND will also include a protocol detailing, among other things, the objectives of the clinical trial, the parameters to be used in monitoring safety and the effectiveness criteria to be evaluated if the first phase or phases of the clinical trial lend themselves to an efficacy determination. The IND will automatically becomebecomes effective 30 days after receipt by the FDA, unless the FDA raises concerns or questions regarding the proposed clinical trials and places the trial on a clinical hold within thethat 30-day time period placesperiod. In such a case, the IND on clinical hold because of safety concerns about the product candidate or the conduct of the trial described in the clinical protocol included in the IND. The IND sponsor and the FDA must resolve any outstanding concerns before the clinical trial can begin. The FDA may also impose clinical holds on a biological product candidate at any time before or during clinical trials can proceed.

Alldue to unacceptable and significant risks to clinical trial subjects or non-compliance with FDA requirements. If the FDA imposes a clinical hold, trials may not begin, continue or recommence in the U.S. without FDA authorization and then only under terms authorized by the FDA. Accordingly, we cannot be sure that submission of an IND will result in the FDA allowing clinical trials for new drugs and biologics must be conductedto begin, or that, once begun, issues will not arise that suspend or terminate the conduct of such trials in the U.S.

Clinical trials involve the administration of the biological product candidate to patients under the supervision of onequalified investigators, generally physicians not employed by or more qualified principal investigators in accordance with GCP. They must beunder the trial sponsor’s control. Clinical trials are conducted under protocols detailing, among other things, the objectives of the applicable phase of theclinical trial, dosing procedures, research subject selectioninclusion and exclusion criteria, and the safety and effectiveness criteriaparameters to be evaluated.used to monitor subject safety, including stopping rules that assure a clinical trial will be stopped if certain adverse events should occur. Each protocol and any amendments to the protocol must be submitted to the FDA as part of the IND,IND. Clinical trials must be conducted and monitored in accordance with the FDA’s regulations comprising the GCP requirements, including the requirement that all research patients provide informed consent. Further, the protocol and amendments, which describe the study design, for each clinical trial must be reviewed and approved by an independent IRB at or servicing each institution at which the clinical trial will be conducted. An IRB is charged with protecting the welfare and rights of trial participants and considers such items as whether the risks to individuals participating in the clinical trials are minimized and are reasonable in relation to anticipated benefits. The IRB also approves the form and content of the informed consent document that must be signed by each clinical trial subject or his or her legal representative and must monitor the clinical trial until completed. Some studies also include oversight by an independent group of qualified experts organized by the clinical study sponsor, known as a data safety monitoring board, which provides authorization for whether or not a study may move forward at designated check points based on access to certain data from the study and may halt the clinical trial if it determines that there is an unacceptable safety risk for subjects or other grounds, such as no demonstration of efficacy. There are also requirements governing the reporting of ongoing clinical studies and clinical study results to public registries.

Human clinical trials are typically conducted in three sequential phases that may overlap or be combined:

Post-approval clinical trials, sometimes referred to as Phase 4 clinical trials, may be conducted, and in some cases are required by the FDA, after initial marketing approval. These clinical trials are used to gain additional experience from the treatment of patients in the intended therapeutic indication, particularly for long-term safety follow-up. During all phases of clinical development, regulatory agencies require extensive monitoring and auditing of all clinical activities, clinical data, and clinical trial investigators. Annual progress reports detailing the statusresults of the clinical trials must be submitted to the FDA annually. SponsorsFDA. Written IND safety reports must also reportbe promptly submitted to the FDA within certain timeframes,and to investigators for serious and unexpected adverse reactions,events, findings from other studies that suggest a significant risk in humans exposed to the drug, laboratory animal testing or in vitro testing that suggest a significant risk to human patients, or any clinically important increase in the rate of a serious suspectedexpected adverse reaction over thatthe rate listed in the protocol or

investigator’s brochure, or any findings from other studies or animal or in vitro testing investigator brochure. The sponsor must submit an IND safety report within 15 calendar days after the sponsor determines that suggest a significant risk in humans exposed to the product candidate. An institutional review board, or IRB, at each institution participating in the clinical trial must review and approve the protocol before a clinical trial commences at that institution, approve the information regardingqualifies for reporting. The sponsor also must notify the trial andFDA of any unexpected fatal or life-threatening suspected adverse reaction within seven calendar days after the consent form that must be provided to each research subject or the subject’s legal representative, and monitor the trial until completed.

Clinical trials are typically conducted in three sequential phases, but the phases may overlap and different trials may be initiated with the same product candidate within the same phase of development in similar or differing patient populations.

Phase 1 clinical studies may be conducted in a limited number of patients or healthy volunteers, as appropriate. The product candidate is initially tested for safety and, as appropriate, for absorption, metabolism, distribution, excretion, pharmacodynamics and pharmacokinetics.

Phase 2 usually involves trials in a larger, but still limited, patient population to evaluate preliminarily the efficacysponsor’s initial receipt of the product candidate for specific, targeted indications to determine dosage tolerance and optimal dosage and to identify possible short-term adverse effects and safety risks.

Phase 3 trials are undertaken to further evaluate clinical efficacy of a specific endpoint and to test further for safety within an expanded patient population at geographically dispersed clinical trial sites.information. Phase 1, Phase 2 orand Phase 3 testing mightclinical trials may not be completed successfully within any specific timespecified period, if at all, with respect to any of our product candidates. Results from one trial are not necessarily predictive of results from later trials. Furthermore, theall. The FDA or the sponsor or its data safety monitoring board may suspend or terminate a clinical trialstrial at any time on various grounds, including a finding that the subjects orproduct candidate to which the research patients are being exposed toposes an unacceptable health risk.risk, including risks inferred from other unrelated immunotherapy trials. Similarly, an IRB can suspend or terminate approval of a clinical trial at its institution if the clinical trial is not being conducted in accordance with the IRB’s requirements or if the biological product candidate has been associated with unexpected serious harm to patients.

Prior to and concurrently with clinical trials, companies usually complete additional studies on and must also develop additional information about the physical characteristics of the biological product as well as finalize a process for manufacturing the product in commercial quantities in accordance with cGMP requirements. To help reduce the risk of the introduction of adventitious agents with use of biological products, the FDCA, PHSA and FDA regulations emphasize the importance of manufacturing control for products whose attributes cannot be precisely defined. The manufacturing process must be capable of consistently producing quality batches of the product candidate and, among other things, the sponsor must develop methods for testing the identity, strength, quality, potency and purity of the final biological product. Additionally, appropriate packaging must be selected and tested, and stability studies must be conducted to demonstrate that the biological product candidate does not undergo unacceptable deterioration over its shelf life.

U.S. BLA Review and Approval Processes

After the completion of clinical trials of a biological product, FDA approval of a BLA for an innovator biological product must be obtained before commercial marketing of the biological product. The BLA submission must include results of the preclinicalproduct development, laboratory and animal studies, and clinicalhuman trials, together with other detailed information, including information on the manufacture and composition of the product, are submitted toproposed labeling and other relevant information. The testing and approval processes require substantial time and effort and there can be no assurance that the FDA as part ofwill accept the BLA for filing and, even if filed, that any approval will be granted on a BLA requesting approval to market the product candidate for a proposed indication. timely basis, if at all.

Under the Prescription Drug User Fee Act, as amended (PDUFA), each BLA must be accompanied by a significant user fee. The FDA adjusts the fees payable to the FDA for reviewing a BLA, as well as annualPDUFA user fees for commercial manufacturing establishments andlicensed innovator biological products on an annual basis. PDUFA also imposes an annual program fee for approvedinnovator biological products. Fee waivers or reductions are available in certain circumstances, including a waiver of the application fee for the first application filed by a small business. Additionally, no user fees are assessed on BLAs for innovator biological products can be substantial but are subject to certain limited deferrals, waivers and reductions that may be available. The fees typically increase each year. Each BLA submitted todesignated as orphan drugs, unless the FDA for approval is reviewed for administrative completeness and reviewability withinproduct also includes a non-orphan indication.

Within 60 days following receipt bysubmission of the application, the FDA ofreviews a BLA submission to determine if it is substantially complete before the application. If the BLA is found complete, the FDA will file the BLA, triggering a full review of the application.agency accepts it for filing. The FDA may refuse to file any BLA that it deems incomplete or not properly reviewable at the time of submission.submission and may request additional information. In this event, the BLA must be resubmitted with the additional information. The FDA’s established goalresubmitted application also is subject to review 90% of priority BLA applications within six months afterbefore the applicationFDA accepts it for filing. Once the submission is accepted for filing, and 90% of standard BLA applications within 10 monthsthe FDA begins an in-depth substantive review of the acceptance date, whereupon a review decision is to be made.BLA. The FDA however,reviews the BLA to determine, among other things, whether the proposed product is safe, potent, and/or effective for its intended use, and has an acceptable purity profile, and whether the product is being manufactured in accordance with cGMP to assure and preserve the product’s identity, safety, strength, quality, potency and purity. The FDA may refer applications for novel biological products or biological products that present difficult questions of safety or efficacy to an advisory committee, typically a panel that includes clinicians and other experts, for review, evaluation and a recommendation as to whether the application should be approved and under what conditions. The FDA is not bound by the recommendations of an advisory committee, but it considers such recommendations carefully when making decisions. During the biological product approval process, the FDA also determines whether a Risk Evaluation and Mitigation Strategy (REMS) is necessary to assure the safe use of the biological product. A REMS is a safety strategy to manage a known or potential serious risk associated with a medicine and to enable patients to have continued access to such medicines by managing their safe use, and could include medication guides, physician communication plans, or elements to assure safe use, such as restricted distribution methods, patient registries and other risk minimization tools. If the FDA concludes a REMS is needed, the sponsor of the BLA must submit and obtain approval for a proposed REMS. The FDA will not approve a product candidate within these established goals and its review goals are subject to change from time to time. Further, the outcome of the review, evenBLA without a REMS, if generally favorable, may not be an actual approval but a “complete response letter” that describes additional work that must be done before the application can be approved. required.

Before approving a BLA, the FDA maywill inspect the facility or facilities at which the product is manufactured andmanufactured. The FDA will not approve the product unless it determines that the facility compliesmanufacturing processes and facilities comply with cGMP.cGMP requirements and are adequate to assure consistent production of the product within required specifications. For immunotherapy products, the FDA also will not approve the product if the manufacturer is not in compliance with the GTPs, to the extent applicable. GTPs are FDA regulations and guidance documents that govern the methods used in, and the facilities and controls used for, the manufacture of human cells, tissue, and cellular and tissue-based products (HCT/Ps), which are human cells or tissue intended for implantation, transplant, infusion, or transfer into a human recipient. The primary intent of the GTP requirements is to ensure that cell and tissue-based products are manufactured in a manner designed to prevent the introduction, transmission and spread of communicable disease. FDA regulations also require tissue establishments to register and list their HCT/Ps with the FDA and, when applicable, to evaluate donors through screening and testing. Additionally, before approving a BLA, the FDA will typically inspect one or more clinical sites to assure that the clinical trials were conducted in compliance with IND trial requirements and GCP requirements. To assure cGMP, GTP and GCP compliance, an applicant must incur significant expenditure of time, money and effort in the areas of training, record keeping, production, and quality control.

Notwithstanding the submission of relevant data and information, the FDA may deny approval of aultimately decide that the BLA if applicable statutory ordoes not satisfy its regulatory criteria for approval and deny approval. Data obtained from clinical trials are not satisfied,always conclusive and the FDA may interpret data differently than we interpret the same data. If the agency decides not to approve the BLA after its review, the FDA will issue a complete response letter that describes the specific deficiencies in the BLA identified by the FDA. The deficiencies identified may be minor, for example, requiring labeling changes, or may requiremajor, for example, requiring additional testing or information, which can extendclinical trials. Additionally, the review process. FDA approval of any applicationcomplete response letter may include many delaysrecommended actions that the applicant might take to place the application in a condition for approval. If a complete response letter is issued, the applicant may either resubmit the BLA, addressing all of the deficiencies identified in the letter, or never be granted. withdraw the application.

If a product is approved,receives regulatory approval, the approval may impose limitations onbe limited to specific diseases and dosages or the usesindications for use may otherwise be limited, which could restrict the product may be marketed,commercial value of the product. Further, the FDA may require that warning statementscertain contraindications, warnings or precautions be included in the product labeling, may require that additional studies be conducted following approval as a condition of the approval, andlabeling. The FDA may impose restrictions and conditions on product distribution, prescribing, or dispensing in the form of a Risk Evaluation and Mitigation Strategy,risk management plan or REMS, or otherwise limit the scope of any approval. TheIn addition, the FDA must approvemay require post marketing clinical trials, sometimes referred to as Phase 4 clinical trials, designed to further assess a BLA supplement or a new BLA before a productbiological product’s safety and effectiveness, and may be marketed for other uses or before certain manufacturing or other changes may be made. Further post-marketingrequire testing and surveillance programs to monitor the safety or efficacy of a product is required. Also, product approvals may be withdrawn if compliance with regulatory standards is not maintained or if safety or manufacturing problems occur following initial marketing. approved products that have been commercialized.

In addition, new government requirements maythe Pediatric Research Equity Act (PREA) requires applicants to study certain drugs and biological products in relevant pediatric subpopulations, with the potential of obtaining pediatric labeling for the product, if the drug is found to be established that could delay or prevent regulatory approvalsafe and effective for use in children. With enactment of our product candidates under development.

Under the Biologics Price CompetitionFood and Drug Administration Safety and Innovation Act of 2009,2012, or FDASIA, sponsors must submit an initial pediatric study plan in the BLA. Pediatric study plans must contain an outline of the proposed pediatric study or studies the applicant plans to conduct, including study objectives and design, any deferral or waiver requests, and other information required by regulation and must be agreed upon by the FDA. The FDA or the BPCIA,applicant may request an amendment to the plan at any time.

The FDA may grant deferrals for submission of data or full or partial waivers for pediatric studies, including the study of all pediatric patients or subpopulations based on age on its own initiative or at the request of the applicant. Additional requirements and procedures relating to deferral requests and requests for extension of deferrals are contained in FDASIA. Unless otherwise required by regulation, the pediatric data requirements do not apply to products with orphan designation. For example, Section 505B of the U.S. Food, Drug and Cosmetic Act, as amended by the FDA Reauthorization Act in 2020, requires that any original NDA or BLA submitted on or after August 18, 2020 for a statutory pathwaynew active ingredient contain reports on molecularly targeted pediatric cancer investigations unless the requirement is waived or deferred, if the drug that is the subject of the application is: (1) intended for the treatment of an adult cancer, and (2) directed at a molecular target that the FDA determines to be substantially relevant to the growth or progression of a pediatric cancer. This requirement applies even if the adult cancer indication does not occur in the pediatric population and even if the drug is for an adult indication for which orphan designation has been createdgranted. Therefore, the BLA of any product we develop that is determined to be substantially relevant to the growth or progression of a pediatric cancer, even if the drug has been designated as an orphan drug for licensure,an adult indication, must contain reports on molecularly targeted pediatric cancer investigations unless such investigations are waived or approval, of biological products that are biosimilar to, and possibly interchangeable with, earlier biological products licensed under the Public Health Service Act. Also under the BPCIA, innovator manufacturers of original reference biological products are granted 12 years of exclusivity before biosimilars can be approved for marketingdeferred.

Orphan Drug Designation in the United States. The approval of a biologic product biosimilar to one of our products could have a material adverse impact on our business as it may be significantly less costly to bring to market and may be priced significantly lower than our products.

Both before and after the FDA approves a product, the manufacturer and the holder or holders of the BLA for the product are subject to comprehensive regulatory oversight. For example, quality control and manufacturing procedures must conform, on an ongoing basis, to cGMP and GTP requirements, as applicable and the FDA periodically inspects manufacturing facilities to assess compliance with these standards. Accordingly, manufacturers must continue to spend time, money and effort to maintain compliance.U.S.

Orphan Drug Act

TheUnder the Orphan Drug Act, provides incentivesthe FDA may grant orphan designation to manufacturersa drug or biologic intended to develop and market drugs fortreat a rare diseases and conditions affectingdisease or condition, which is generally a disease or condition that affects fewer than 200,000 personsindividuals in the United States, ator more than 200,000 individuals in the timeU.S. and for which there is no reasonable expectation that the cost of applicationdeveloping and making available in the U.S. a drug or biologic for orphanthis type of disease or condition will be recovered from sales in the U.S. for that drug designation.or biologic. Orphan drug designation must be requested before submitting a BLA. OrphanAfter the FDA grants orphan drug designation, the generic identity of the therapeutic agent and its potential orphan use are disclosed publicly by the FDA. The orphan drug designation does not convey any advantage in, or shorten the duration of, the regulatory review andor approval process.

If a product that has orphan drug designation subsequently receives the first FDA approval for the disease for which it has such designation, the holder of the approvalproduct is entitled to a seven-year exclusive marketing period in the United States for thatorphan product except in very limited circumstances. For example, a drugexclusivity, which means that the FDA considersmay not approve any other applications, including a full BLA, to be clinically superior to, or different from, another approved orphan drug, even thoughmarket the same biologic for the same indication for seven years, except in limited circumstances, such as a showing of clinical superiority to the product with orphan drug exclusivity. Orphan drug exclusivity does not prevent the FDA from approving a different drug or biologic for the same disease or condition, or the same drug or biologic for a different disease or condition. Among the other benefits of orphan drug designation are tax credits for certain research and a waiver of the BLA application user fee.

A designated orphan drug may also obtain approvalnot receive orphan drug exclusivity if it is approved for a use that is broader than the indication for which it received orphan designation. In addition, exclusive marketing rights in the United States duringU.S. may be lost if the seven-year exclusive marketing period. In addition, holders of exclusivityFDA later determines that the request for orphan drugs are expecteddesignation was materially defective or if the manufacturer is unable to assure the availability of sufficient quantities of their orphan drugsthe product to meet the needs of patients. Failure to do so could resultpatients with the rare disease or condition.

Expedited Development and Review Programs in the withdrawal of marketing exclusivity for the drug.U.S.

Legislation similar to the Orphan Drug Act has been enacted outside the United States, including in the EU. The orphan legislation in the EU is available for therapies addressing chronic debilitating or life-threatening conditions that affect five or fewer out of 10,000 persons or are financially not viable to develop. The market exclusivity period is for ten years, although that period can be reduced to six years if, at the end of the fifth year, available evidence establishes that the product is sufficiently profitable not to justify maintenance of market exclusivity. The market exclusivity may be extended to 12 years if the sponsor completes a pediatric investigation plan agreed upon with the relevant committee of the EMA.

Expedited Review and Approval

The FDA has various programs, including Fast Track and Regenerative Medicine Advanced Therapy, or RMAT, priority review and accelerated approval, which area fast track program that is intended to expedite or simplifyfacilitate the process for developing and reviewing promising drugs, or to provide for the approval of a drug on the basis of a surrogate endpoint. Even if a drug qualifies for one or more of these programs, the FDA may later decidenew products that the drug no longer meets the conditions for qualification or that the time period for FDA review or approval will be shortened. Generally, drugs thatmeet certain criteria. Specifically, new products are eligible for these programsfast track designation if they are those for serious or life-threatening conditions, those with the potential to address unmet medical needs and those that offer meaningful benefits over existing treatments. For example, Fast Track and RMAT are processes designed to facilitate the development and expedite the review of drugs to treat serious or life-threatening diseases or conditions and fill unmet medical needs. Priority review is designed to give drugs that offer major advances in treatment or provide a treatment where no adequate therapy exists an initial review within six months as compared to a standard review time of 10 months. Although Fast Track, RMAT, and priority review do not affect the standards for approval, the FDA will attempt to facilitate early and frequent meetings with a sponsor of a Fast Track designated drug and expedite review of the application for a drug designated for priority review. Accelerated approval provides for an earlier approval for a new drug that is intended to treat a serious or life-threatening disease or condition and that fillsdemonstrate the potential to address an unmet medical need basedfor the disease or condition. Fast track designation applies to the combination of the product and the specific indication for which it is being studied. For a product that

has received fast track designation, the FDA may consider for review sections of the BLA on a rolling basis before the complete application is submitted. A sponsor seeking a rolling submission must provide a schedule for the submission of each section of the BLA, and the FDA must agree to the rolling submission and that the schedule is acceptable. In addition, the sponsor must pay any required user fees upon submission of the first section of the BLA. Submission of sections of a BLA on a rolling basis does not guarantee that the FDA will begin their review of these sections upon receipt or even before the BLA submission is deemed to be complete. Therefore, a rolling BLA submission may not result in a faster timeline to marketing approval. Additionally, a rolling BLA submission has no bearing on whether or not a product candidate is ultimately approved.

Any product, including a product with a fast track designation, may also be eligible for other types of FDA programs intended to expedite development and review, such as priority review and accelerated approval. A product is eligible for priority review if it is intended for treatment of a serious condition and has the potential to provide safe and effective therapy where no satisfactory alternative therapy exists or a significant improvement in the treatment, diagnosis or prevention of a disease compared to marketed products. The FDA will attempt to direct additional resources to the evaluation of an application for a new product designated for priority review in an effort to facilitate the review. The FDA intends to take action on applications under priority review within 6 months of the application filing date compared with 10 months from the filing date for standard review.

Additionally, a product may be eligible for accelerated approval. Products studied for their safety and effectiveness in treating serious or life-threatening diseases or conditions may receive accelerated approval upon a determination that the product has an effect on a surrogate endpoint. A surrogate endpoint that is reasonably likely to predict clinical benefit, or on a laboratory measurementclinical endpoint that can be measured earlier than irreversible morbidity or physical sign used asmortality, that is reasonably likely to predict an indirecteffect on irreversible morbidity or substitute measurement representing a clinically meaningful outcome.mortality or other clinical benefit, taking into account the severity, rarity, or prevalence of the condition and the availability or lack of alternative treatments. As a condition of approval, the FDA may require that a sponsor of a drug or biological product candidate receiving accelerated approval perform adequate and well-controlled post-marketing clinical trialsstudies to confirm the clinically meaningful outcome as predicted by the surrogate marker trial.

demonstrate clinical benefit. In addition, to the Fast Track,FDA currently requires as a condition for accelerated approval pre-approval of promotional materials, which could adversely impact the timing of the commercial launch of the product.

Regenerative Medicine Advanced Therapy (RMAT) designation was established by FDA in 2017 to facilitate an efficient development program for, and priorityexpedite review programs discussed above, breakthrough therapy designation may be pursued. A breakthrough therapyof, any drug that meets the following criteria: (1) it qualifies as a RMAT, which is defined as a drug thatcell therapy, therapeutic tissue engineering product, human cell and tissue product, or any combination product using such therapies or products, with limited exceptions; (2) it is intended aloneto treat, modify, reverse, or in combination with one or more other drugs, to treatcure a serious or life-threatening disease or condition,condition; and (3) preliminary clinical evidence indicates that the drug has the potential to address unmet medical needs for such a disease or condition. RMAT designation provides potential benefits that include more frequent meetings with FDA to discuss the development plan for the product candidate and eligibility for rolling review and priority review. Products granted RMAT designation may demonstratealso be eligible for accelerated approval on the basis of a surrogate or intermediate endpoint reasonably likely to predict long-term clinical benefit, or reliance upon data obtained from a meaningful number of sites, including through expansion to additional sites. Once approved, when appropriate, the FDA can permit fulfillment of post-approval requirements under accelerated approval through the submission of clinical evidence, clinical studies, patient registries, or other sources of real-world evidence such as electronic health records; through the collection of larger confirmatory datasets; or through post-approval monitoring of all patients treated with the therapy prior to approval.

Breakthrough therapy designation is also intended to expedite the development and review of products that treat serious or life-threatening conditions. The designation by FDA requires preliminary clinical evidence that a product candidate, alone or in combination with other drugs and biologics, demonstrates substantial improvement over existing therapiescurrently available therapy on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. Drugs designated asBreakthrough therapy designation comes with all of the benefits of Fast Track designation, which means that the sponsor may file sections of the BLA for review on a rolling basis if certain conditions are satisfied, including an agreement with FDA on the proposed schedule for submission of portions of the application and the payment of applicable user fees before the FDA may initiate a review.

Fast Track designation, priority review, RMAT and breakthrough therapies are also eligibletherapy designation do not change the standards for accelerated approval.approval but may expedite the development or approval process. The FDA will seekmay revoke any of these designations if the product no longer meets applicable criteria.

Post-Approval Requirements in the U.S.

Any products for which we receive FDA approvals are subject to continuing regulation by the FDA, including, among other things, record-keeping requirements, reporting of adverse experiences with the product, providing the FDA with updated safety and efficacy information, product sampling and distribution requirements, and complying with FDA promotion and advertising requirements, which include, among others, standards for direct-to-consumer advertising, restrictions on promoting products for uses or in patient populations that are not described in the product’s approved uses (known as “off-label use”), limitations on industry-sponsored scientific and educational activities, and requirements for promotional activities involving the internet. Although a physician may prescribe a legally available product for an off-label use, if the physician deems such product to be appropriate in his/her professional medical judgment, a manufacturer may not market or promote off-label uses. However, it is permissible to share in certain circumstances truthful and not misleading information that is consistent with the product’s approved labeling.

In addition, the distribution of prescription drug products, including most biological products that require a prescription, are subject to the Prescription Drug Marketing Act, or the PDMA, which regulates the distribution of drug samples at the federal level, and sets minimum standards for the registration and regulation of drug distributors by the states. Both the PDMA and state laws limit the distribution of prescription drug product samples and impose requirements to ensure accountability in distribution.

Furthermore, quality control and manufacturing procedures must continue to conform to applicable manufacturing requirements after approval to ensure the sponsorlong-term stability of the product. cGMP regulations require among other things, quality control and quality assurance as well as the corresponding maintenance of records and documentation and the obligation to investigate and correct any deviations from cGMP. Manufacturers and other entities involved in the manufacture and distribution of approved products are required to register their establishments with the FDA and certain state agencies, and are subject to periodic unannounced inspections by the FDA and certain state agencies for compliance with cGMP and other laws. Accordingly, manufacturers must continue to expend time, money, and effort in production and quality control to maintain cGMP compliance. Discovery of problems with a product after approval may result in restrictions on a product, manufacturer, or holder of an approved BLA, including, among other things, recall or withdrawal of the product from the market. In addition, changes to the manufacturing process are strictly regulated, and depending on the significance of the change, may require prior FDA approval before being implemented. Other types of changes to the approved product, such as adding new indications and claims, are also subject to further FDA review and approval.

The FDA also may require post-marketing testing, known as Phase 4 testing, and surveillance to monitor the effects of an approved product. Discovery of previously unknown problems with a product or the failure to comply with applicable FDA requirements can have negative consequences, including adverse publicity, judicial or administrative enforcement, warning letters from the FDA, mandated corrective advertising or communications with doctors, and civil or criminal penalties, among others. Newly discovered or developed safety or effectiveness data may require changes to a product’s approved labeling, including the addition of new warnings and contraindications, and also may require the implementation of other risk management measures, for example, a REMS. Also, new government requirements, including those resulting from new legislation, may be established, or the FDA’s policies may change, which could delay or prevent regulatory approval of our products under development.

U.S. Marketing Exclusivity

The Biologics Price Competition and Innovation Act (BPCIA) amended the PHSA to authorize the FDA to approve similar versions of innovative biologics, commonly known as biosimilars. A competitor seeking approval of a breakthrough therapybiosimilar must file an application to establish that its molecule is highly similar to an approved innovator biologic, notwithstanding minor differences in clinically inactive components, and shows no clinically meaningful differences between the biological product candidate receives: intensive guidanceand the reference product in terms of safety, purity, and potency, which can generally be shown through analytical studies, animal studies, and a clinical study or studies. Separately, a product that is biosimilar to the reference product is considered interchangeable if the product demonstrates that it can be expected to produce the same clinical results as the reference product in any given patient and, for products that are administered multiple times to an individual, the interchangeable biosimilar and the reference biological product may be alternated or switched after one has been previously administered without increasing safety risks or risks of diminished efficacy relative to exclusive use of the reference biological product. If a product is shown to be biosimilar or interchangeable with an FDA-approved reference biologic, this can potentially reduce the cost and time required to obtain approval to market the biosimilar or interchangeable product. Complexities associated with the larger, and often more complex, structures of biological products, as well as the processes by which such products are manufactured, pose significant hurdles and have slowed implementation of the BPCIA by the FDA.

The BPCIA, however, bars the submission of BLAs for biosimilars to an approved application until four years after the licensure date for the reference biologic. In addition, the FDA may not approve biosimilar applications for 12 years after an innovator biological product receives initial marketing approval. During this 12-year period of reference product exclusivity, another company may obtain FDA licensure and market a competing version of the reference product if the FDA approves a full BLA for the competing

product containing that applicant’s own preclinical data and data from adequate and well controlled clinical trials to demonstrate the safety, purity and potency of its product. The BPCIA also created certain exclusivity periods for biosimilars approved as interchangeable products. At this juncture, it is unclear whether products deemed “interchangeable” by the FDA will, in fact, be readily substituted by pharmacies, which are governed by state pharmacy law. This 12-year period of data exclusivity may be extended by six months, for a total of 12.5 years, if the FDA requests, and the innovator company completes pediatric clinical investigations of the product.

The development and, if approved, marketing of biosimilars is subject to user fees under the Biosimilar User Fee Amendments of 2022 (BsUFA), which currently apply through September 2027 and may be renewed or amended thereafter. Sponsors must submit an initial biosimilar biological product development (BPD) fee on the earlier of the submission of an IND or within 7 calendar days of FDA granting a first BPD meeting, and annually thereafter until the sponsor submits a BLA that is accepted for filing, or the sponsor discontinues participation in the BPD program. FDA may also remove a sponsor from the BPD program if the sponsor has failed to pay annual BPD fees for a period of 2 consecutive fiscal years. Sponsors who discontinue participation in the BPD program but want to reengage FDA on product development must also pay all prior assessed BPD fees still owed and a reactivation fee and will be subject to annual BPD fees. Once a sponsor submits a BLA for a biosimilar, they are subject to application fees. And, once a biosimilar BLA is approved, the sponsor is subject to annual program fees. The FDA amends the specific fee amounts under BsUFA on an efficient drugannual basis.

The BPCIA is complex and continues to be interpreted and implemented by the FDA. In addition, there has been discussion of whether Congress should reduce the 12-year reference product exclusivity period. Other aspects of the BPCIA, some of which may impact the BPCIA exclusivity provisions, have also been the subject of recent litigation. As a result, the ultimate implementation of the BPCIA is subject to significant uncertainty.

Depending upon the timing, duration and specifics of the FDA approval of the use of our product candidates, some of our U.S. patents, if granted, may be eligible for limited patent term extension under the Drug Price Competition and Patent Term Restoration Act of 1984, commonly referred to as the Hatch-Waxman Act. The Hatch-Waxman Act permits a patent restoration term of up to five years, as compensation for patent term lost during product development program; intensive involvementand the FDA regulatory review process. However, patent term restoration cannot extend the remaining term of senior managersa patent beyond a total of 14 years from the product’s approval date. The patent term restoration period is generally one-half the time between the effective date of an IND and experienced staffthe submission date of a BLA plus the time between the submission date of a BLA and the approval of that application. Only one patent applicable to an approved product is eligible for the extension and the application for the extension must be submitted prior to the expiration of the patent. The U.S. Patent and Trademark Office, in consultation with the FDA, reviews and approves the application for any patent term extension or restoration. In the future, we may intend to apply for restoration of patent term for one of our currently owned or licensed patents to add patent life beyond its current expiration date, depending on a proactive, collaborativethe expected length of the clinical trials and cross-disciplinary review; and rolling review.other factors involved in the filing of the relevant BLA.

Reimbursement of Approved Products in the U.S.

In both domestic and foreign markets, sales and reimbursement of any approved products will depend, in part, on the extent to which the costs of such products will be covered by third-partythird party payors, such as government health programs, commercial insurance and managed healthcare organizations. Third party payors determine which medications they will cover and establish reimbursement amounts. There may be significant delays in obtaining coverage and reimbursement for newly approved drugs, and coverage may be more limited than the purposes for which the drug is approved by the FDA or comparable foreign regulatory authorities. Interim reimbursement amounts for new drugs, if applicable, may also be insufficient to cover our costs and may only be temporary. Reimbursement rates may vary according to the use of the drug and the clinical setting in which it is used, may be based on reimbursement levels already set for lower cost drugs and may be incorporated into existing payments for other services. Net prices for drugs may be reduced by mandatory discounts or rebates required by government healthcare programs or private payors and by any future relaxation of laws that presently restrict imports of drugs from countries where they may be sold at lower prices than in the U.S. Coverage and reimbursement policies for drug products can differ significantly from payor to payor as there is no uniform policy of coverage and reimbursement for drug products among third party payors in the U.S. Third party payors in the U.S. often rely upon Medicare coverage policy and payment limitations in setting their own reimbursement policies. There may be significant delays in obtaining coverage and reimbursement as the process of determining coverage and reimbursement is often time consuming and costly which will require us to provide scientific and clinical support for the use of our products to each payor separately, with no assurance that coverage or adequate reimbursement will be obtained. It is difficult to predict at this time what government authorities and third party payors will decide with respect to coverage and reimbursement for our drug products.

These third-partythird party payors are increasingly challenging the prices charged for medical products and services and imposing controls to manage costs. The containment of healthcare costs has become a priority of federal and state governments and the prices of drugs have been a focus in this effort. Governments have shown significant interest in implementing

cost-containment programs,

including price controls, restrictions on reimbursement and requirements for substitution of generic products. For example,In the U.S. there have been several recent U.S. Congressional inquiries and proposed and enacted federal and state legislation designed to, among other things, bring more transparency to drug pricing, review the relationship between pricing and manufacturer patient programs, reduce the cost of drugs under Medicare, and reform government program reimbursement methodologies for drugs. Further,For example, included in the Consolidated Appropriations Act of 2021 were several drug price reporting and transparency measures, such as a new requirement for certain Medicare plans to develop tools to display Medicare Part D prescription drug benefit information in real time and for group and health insurance issuers to report information on pharmacy benefit and drug costs to the Secretaries of the Departments of Health and Human Services, Labor and the Treasury. Additionally, on July 9, 2021, President Biden issued an Executive Order to promote competition in the U.S. economy that included several initiatives addressing prescription drugs. Among other provisions, the Executive Order stated that the Biden administration will “support aggressive legislative reforms that would lower prescription drugs, including by allowing Medicare to negotiate drug prices, by imposing inflation caps, and through other related reforms.” In response to the Executive Order, on September 9, 2021, the Department of Health and Human Services issued a Comprehensive Plan for Addressing High Drug Prices that identified potential legislative policies and administrative tools that Congress and the Trump administration have each indicatedagency can pursue in order to make drug prices more affordable and equitable, improve and promote competition throughout the prescription drug industry, and foster scientific innovation. Most recently, in August 2022, President Biden signed into law the Inflation Reduction Act of 2022 (IRA), which implements substantial changes to the Medicare program, including drug pricing reforms and changes to the Medicare Part D benefit design. Among other reforms, the IRA imposes inflation rebates on drug manufacturers for products reimbursed under Medicare Parts B and D if the prices of those products increase faster than inflation; implements changes to the Medicare Part D benefit that, itbeginning in 2025, will continue to seekcap benefit annual out-of-pocket spending at $2,000 while imposing new legislative and/or administrative measures to control drug costs.discount obligations for pharmaceutical manufacturers; and, beginning in 2026, establishes a “maximum fair price” for a fixed number of pharmaceutical and biological products covered under Medicare Parts B and D following a price negotiation process with the Centers for Medicare and Medicaid Services. At the state level, legislatures have increasingly passed legislation and implemented regulations designed to control pharmaceutical and biological product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, to encourage importation from other countries and bulk purchasing.Adoption of price controls and cost-containment measures, and adoption of more restrictive policies in jurisdictions with existing controls and measures, could further limit our net revenue and results. In addition, there is significant uncertainty regarding the reimbursement status of newly approved healthcare products. We may need to conduct expensive pharmacoeconomic studies in order to demonstrate the cost-effectiveness of our products. If third-party payors do not consider our products to be cost-effective compared to other therapies, the payors may not cover our products after approved as a benefit under their plans or, if they do, the level of payment may not be sufficient to allow us to sell our products on a profitable basis.

Within the United States,U.S., if we obtain appropriate approval in the future to market any of our current product candidates, we may seek approval and coverage for those products under Medicaid, Medicare and the Public Health Service or PHS,(PHS), pharmaceutical pricing program and also seek to sell the products to federal agencies.

Medicaid is a joint federal and state program that is administered by the states for low income and disabled beneficiaries. Under the Medicaid Drug Rebate Program, manufacturers are required to pay a rebate for each unit of producta covered outpatient drug reimbursed by the state Medicaid programs. The amount of the rebate for each product is set by law and may be subject to an additional discount if certain pricing increases more than inflation.

Medicare is a federal program administered by the federal government that covers individuals age 65 and over as well as those with certain disabilities. Medicare Part D provides coverage to enrolled Medicare patients for self-administered, outpatient drugs (i.e., drugs typically dispensed by a pharmacy and that do not need to be administered by a physician). Medicare Part D is administered by private prescription drug plans approved by the U.S. government and each drug plan establishes its own Medicare Part D formulary for prescription drug coverage and pricing, subject to CMS rules and requirements, which the drug plan may modify from time-to-time.

Medicare Part B covers most injectable drugs given in an in-patient setting, and some drugs administered by a licensed medical provider in hospital outpatient departments and doctors’ offices. Medicare Part B is administered by Medicare Administrative Contractors, which generally have the responsibility of making coverage decisions.decisions in accordance with CMS rules and requirements. Subject to certain payment adjustments and limits, Medicare generally pays for Part B covered drugs based on a percentage of manufacturer-reported average sales price.

Drug products are subject to discounted pricing when purchased by federal agencies via the Federal Supply Schedule or FSS.

FFS(FSS). FSS participation is required for a drug product to be covered and paid for by certain federal agencies and for coverage under Medicaid, Medicare Part B and the PHS pharmaceutical pricing program.program, commonly referred to as the 340B Drug Pricing Program. FSS pricing is negotiated periodically with the Department of Veterans Affairs. FSS pricing is intended to not exceed the price that a manufacturer charges its most-favored non-federal customer for its product. In addition, prices for drugs purchased by the Veterans Administration, Department of Defense (including drugs purchased by military personnel and dependents through the TRICARE retail pharmacy program), Coast Guard, and PHS are subject to a cap on pricing (known as the “federal ceiling price”) and may be subject to an additional discount if pricing increases more than inflation.

To maintain coverage of drugs under the Medicaid Drug Rebate Program, manufacturers are required to extend discounts to certain purchasers under the PHS pharmaceutical pricing program. Purchasers eligible for discounts include hospitals that serve a

disproportionate share of financially needy patients, community health clinics and other entities that receive health services grants from the PHS.

The United States and state governments continue to propose and pass legislation designed to reduce the cost of healthcare. In March 2010, the United StatesU.S. Congress enacted the Patient Protection and Affordable Care Act, andas amended by the Health Care and Education Reconciliation Act or(collectively, the Affordable Care Act,Act), which included changes to the coverage and payment for drug products under government health care programs. Some of the provisions of the Affordable Care Act have yet to be implemented, andSince its enactment, there have been judicial and Congressional challenges to certain aspectsnumerous elements of the Affordable Care Act, as well as recent efforts by both the Trump administrationexecutive and legislative branches of the federal government to repeal or replace certain aspects of the Affordable Care Act. Since January 2017, President TrumpFor example, while Congress has signed two Executive Orders designed to delay the implementation ofnot passed comprehensive repeal legislation, it has enacted laws that modify certain provisions of the Affordable Care Act, or otherwise circumvent some of the requirementssuch as removing penalties, starting January 1, 2019, for health insurance mandated bynot complying with the Affordable Care Act. Concurrently, Congress has considered legislation that would repeal or repeal and replace all or part of the Affordable Care Act. While Congress has not passed comprehensive repeal legislation, two bills affecting the implementation of certain taxes under the Affordable Care Act have been

enacted. The Tax Cuts and Jobs Act of 2017 includes a provision repealing, effective January 1, 2019, the tax-based shared responsibility payment imposed by the Affordable Care Act on certain individuals who failAct’s individual mandate to maintain qualifyingcarry health coverage for all or part of a year that is commonly referred to as the “individual mandate”. Additionally, on January 22, 2018, President Trump signed a continuing resolution on appropriations for fiscal year 2018 that delayedinsurance, delaying the implementation of certain mandated fees, underand increasing the point-of-sale coverage gap discount that is owed by pharmaceutical manufacturers who participate in Medicare Part D. In June 2021, the U.S. Supreme Court dismissed a lawsuit challenging the constitutionality of certain aspects of the ACA, without ruling on the merits of the constitutionality arguments. Additionally, the American Rescue Plan of 2021, Pub. L. No. 117-2, enacted on March 11, 2021, temporarily increased premium tax credit assistance for those eligible for subsidies for 2021 and 2022 and removed the 400% federal poverty level limit that otherwise applies for purposes of eligibility to receive premium tax credits. Most recently, the IRA extended this increased tax credit assistance and removal of the 400% federal poverty limit through 2025.It is unclear how the healthcare reform measures of the Biden administration and any future litigation will impact the Affordable Care Act and our business.

U.S. Health Care Laws

Healthcare providers and third party payors will play a primary role in the recommendation and prescription of any product candidates for which we obtain regulatory approval. Our current and future arrangements with third party payors and customers may expose us to broadly applicable fraud and abuse and other healthcare laws and regulations that may constrain the business or financial arrangements and relationships through which we conduct research and would market, sell and distribute our products. As a biopharmaceutical company, even though we do not and will not control referrals of healthcare services or bill directly to Medicare, Medicaid or other third party payors, federal and state healthcare laws and regulations pertaining to fraud and abuse and patients’ rights are and will be applicable to our business. Restrictions under applicable federal and state healthcare laws and regulations that may affect our ability to operate include the following:

In the EU, companies developing a new medicinal product must agree to a pediatric investigation plan (PIP) with the EMA and must conduct pediatric clinical trials in accordance with that PIP. The MAA for the product must include the results of pediatric clinical trials conducted in accordance with the PIP, unless a waiver applies, in which case studies in children are not required (for example, if the disease or condition occurs only in adults). or a deferral has been granted, in which case the pediatric clinical trials must be completed at a later date. Products granted a marketing authorization on non-exempt medical devices. Congress also could consider additional legislation to repeal or replace other elementsthe basis of pediatric clinical trials conducted in accordance with the PIP are eligible for a six month extension of the Affordable Care Act.protection under a supplementary protection certificate (if any is in effect at the time of approval) or, in the case of orphan medicinal products, a two year extension of the orphan market exclusivity. This pediatric reward is subject to specific conditions and is not automatically available when data in compliance with the PIP are developed and submitted.

Outside the United States,U.S., there are additional challenges in ensuring adequate coverage and payment for our products will face challenges.products. Pricing of prescription pharmaceuticals is subject to governmental control in many countries. Pricing negotiations with governmental authorities can extend well beyond the receipt of regulatory approval for a product and may require us to conduct a clinical trialstudy that compares the cost effectiveness of our product candidates or products to other available therapies. The conduct of such athis type of clinical trialstudy could be expensive and result in delays into our or our commercialization partners’ commercialization efforts. Third-partyThird party payors are challenging the prices charged for medical products and services, and many third-partythird party payors limit reimbursement for newly-approved health care products. Recent budgetaryBudgetary pressures in many European UnionEU countries are also causing governments to consider or implement various cost-containment measures, such as price freezes, increased price cuts and rebates. If budget pressures continue, governments may implement additional cost-containment measures. Cost-control initiatives could decrease the price we might establish for products that we may develop or sell, which would result in lower product revenues or royalties payable to us. There can be no assurance that any country that haswith price controls or reimbursement limitations for pharmaceutical products will allow favorable reimbursement and pricing arrangements for any of our products.

Foreign RegulationThe EC is currently conducting a wholesale review of the pharmaceutical legal framework, which includes the regulatory protection afforded to medicinal products such as data exclusivity, marketing protection, market exclusivity for orphan indications and pediatric extension. It is expected that the protection currently afforded in the EU will be reduced in the years to come and the new EU

legislative proposal is expected to be published by the EC in the second quarter of 2023, although this timeline may be further prolonged.

In addition to regulationsBrexit and the Regulatory Framework in the United States, we expectKingdom

Following the result of a referendum in 2016, the United Kingdom (UK) left the EU on January 31, 2020, commonly referred to beas Brexit. Pursuant to the formal withdrawal arrangements agreed between the UK and the EU, the UK was subject to a varietytransition period until December 31, 2020 (the Transition Period) during which EU rules continued to apply. A UK-EU Trade and Cooperation Agreement (the Deal) that outlines the future trading relationship between the UK and the EU was agreed in December 2020 and approved by each EU member state and the UK.

Since a significant proportion of foreignthe regulatory framework in the UK applicable to our business and our product candidates is derived from EU directives and regulations, governing clinical trialsUK Legislation has retained existing EU law. However, new UK legislation is being drafted and commercial salesthe UK has not implemented new EU law, such as the CTR; therefore Brexit has had, and distributionwill continue to have, a material impact upon the regulatory regime with respect to the development, manufacture, importation, approval and commercialization of our product candidates. Whethercandidates in the UK and the EU. Great Britain (made up of England, Scotland and Wales) is no longer covered by the EEA’s procedures for the grant of marketing authorizations (Northern Ireland will be covered by the centralized authorization procedure and can be covered under the decentralized or not we obtain FDA approval for a product candidate, we must obtain approval from the comparable regulatory authorities of foreign countries or economic areas, suchmutual recognition procedures, as the European Union, before we may commence clinical trialsEU legal framework continues to apply in Northern Ireland, under the Northern Ireland Protocol). A separate marketing authorization will be required to market drugs in Great Britain. It is currently unclear whether the Medical Healthcare products Regulatory Agency (MHRA) in the United Kingdom is sufficiently prepared to handle the increased volume of MAAs that it is likely to receive. Any delay in obtaining, or marketan inability to obtain, any marketing approvals, would delay or prevent us from commercializing our product candidates in the UK or the EU and restrict our ability to generate revenue and achieve and sustain profitability.

While the Deal provides for the tariff-free trade of medicinal products in those countries or areas. The approval process and requirements governingbetween the conduct of clinical trials, product licensing, pricing and reimbursement vary greatly from place to place,UK and the timeEU there may be longer or shorter than that required for FDA approval.

Certain countries outside of the United States have a process that requires the submission of a clinical trial application, or CTA, much like an INDadditional non-tariff costs to such trade which did not exist prior to the commencementend of human clinical trials. In Europe, for example,the Transition Period. Further, should the UK diverge from the EU from a CTA mustregulatory perspective in relation to medicinal products, tariffs could be submittedput into place in the future. We could therefore, both now and in the future, face significant additional expenses (when compared to the competent national health authority and to independent ethics committees in each country in which a company intends to conduct clinical trials. Once the CTA is approved in accordance with a country’s requirements, clinical trial development may proceed in that country. In all cases, the clinical trials must be conducted in accordance with GCP and other applicable regulatory requirements.

Under European Union regulatory systems, a company may submit marketing authorization applications either under a centralized or decentralized procedure. The centralized procedure is compulsory for medicinal products produced by biotechnology or those medicinal products containing new active substances for specific indications such as the treatment of AIDS, cancer, neurodegenerative disorders, diabetes, viral diseases and designated orphan medicines, and optional for other medicines which are highly innovative. Under the centralized procedure, a marketing application is submittedposition prior to the European Medicines Agency,end of the Transition Period) to operate our business, which could significantly and materially harm or EMA, wheredelay our ability to generate revenues or achieve profitability of our business. Any further changes in international trade, tariff and import/export regulations as a result of Brexit or otherwise may impose unexpected duty costs or other non-tariff barriers on us. These developments, or the perception that any of them could occur, may significantly reduce global trade and, in particular, trade between the impacted nations and the UK. It is also possible that Brexit may negatively affect our ability to attract and retain employees, particularly those from the EU.

Orphan designation in Great Britain following Brexit is granted on an essentially identical basis as it is in the EU, but is based on the prevalence of the condition in Great Britain. It is therefore possible that conditions currently designated as orphan conditions in Great Britain will no longer be designated as such and that conditions that are not currently designated as orphan conditions in the EU will be evaluated by the Committee for Medicinal Products for Human Use and a favorable opinion typically resultsdesignated as such in the grant by the European Commission of a single marketing authorization that is valid for all European Union member states within 67 days of receipt of the opinion. The initial marketing authorization is valid for five years, but once renewed is usually valid for an unlimited period. As with accelerated approval in the U.S., conditional marketing authorization in the European Union is permitted based on incomplete clinical data for a limited number of medicinal products for human use, including products designated as orphan medicinal products under EUlaw, if (1) the risk-benefit balance of the product is positive, (2) it is likely that the applicant will be in a position to provide the required comprehensive clinical trial data, (3) unmet medical needs will be fulfilled and (4) the benefit to public health of the immediate availability on the market of the medicinal product outweighs the risk inherent in the fact that additional data are still required. Specific obligations, including with respect to the completion of ongoing or new studies, and with respect to the collection of pharmacovigilance data, may be specified in the conditional marketing authorization. Conditional marketing authorizations are valid for one year and may be renewed annually, if the risk-benefit balance remains positive, and after an assessment of the need for additional or modified conditions.Great Britain.

As in the United States, we may apply for designation of a product as an orphan drug for the treatment of a specific indication in the European Union before the application for marketing authorization is made. Orphan drugs in Europe enjoy economic and marketing benefits, including up to 11 years of exclusivity for the approved indication unless another applicant can show that its product is safer, more effective or otherwise clinically superior to the orphan designated product. The PRIority MEdicines, or PRIME, initiative was established by the EMA to help promote and foster the development of new medicines in the European Union that demonstrate potential for a major therapeutic advantage in areas of unmet medical need. Benefits from the PRIME designation include early confirmation of potential for accelerated assessment, early dialogue and increased interaction with relevant regulatory committees to discuss development options, scientific advice at key development milestones, and proactive regulatory support from the EMA.

Additional Regulation

As a pharmaceuticalbiopharmaceutical company, even though we do not and will not control referrals of healthcare services or bill directly to Medicare, Medicaid or other third-partythird party payors, federal and state healthcare laws and regulations pertaining to fraud and abuse and patients’ rights are and will be applicable to our business. We are also subject to regulation under the Occupational Safety and Health Act, the Environmental Protection Act, the Toxic Substances Control Act, the Resource Conservation and Recovery Act and other present and potential federal, state or local regulations. These and other laws govern our use, handling and disposal of various biological and chemical substances used in, and waste generated by, our operations. Our research and development involvesinvolve the controlled use of hazardous materials, chemicals and viruses. Although we believe that our safety procedures for handling and disposing of such materials comply with the standards prescribed by state and federal regulations, the risk of accidental contamination or injury from these materials cannot be completely eliminated. In the event of such an accident, we could be held liable for any damages that result, and any such liability could exceed our resources.

There have been a numberManufacturing

In April 2022, we sold all of federalour right, title and state proposals during the last few years regarding the pricing of pharmaceuticalinterest in and biological products, government control and other changesto certain assets related to the healthcare systemAtara T-Cell Operations and Manufacturing facility (ATOM Facility) located in Thousand Oaks, California to FDB. We also entered into a Master Services and Supply Agreement with FDB (Fujifilm MSA) which became effective in April 2022 and could extend for up to ten years. Pursuant to

the Fujifilm MSA, FDB will supply us with specified quantities of our product and product candidates, manufactured in accordance with cGMP standards. The Fujifilm MSA does not obligate us to purchase our product and product candidates exclusively from FDB.

We continue to scale our EBV T-cell manufacturing platform to improve product yields from a single donor leukapheresis collection and have generated data confirming the use of stirred-tank bioreactors to improve yield and cell growth productivity. We believe our scalable technology can potentially be a key enabler to deliver biologic-like cost of goods manufactured and could be leveraged across our portfolio, including our CAR T programs.

In addition to FDB, we also work with Charles River Laboratories Inc. (CRL) pursuant to a Commercial Manufacturing Services Agreement (CRL MSA) that we entered into in December 2019. Pursuant to the CRL MSA, CRL provides manufacturing services for our product and certain intermediates. We further amended the CRL MSA to extend the term until the earlier of March 31, 2024 or upon receipt of certain batches of our product and intermediates. We are currently in negotiations with CRL for a new commercial drug product supply agreement to be effective upon the expiration of the United States. It is uncertain what legislative proposalsCRL MSA. However, there can be no assurance that we will be adoptedable to enter into a new commercial drug product supply agreement with CRL on terms favorable or what actions federal, stateacceptable to us, or private payers for medical goods and servicesat all. If we are unable to enter into a new commercial drug product supply agreement or extend the CRL MSA, we may take in responseneed to any healthcare reform proposals or legislation. We cannot predict the effect medical or healthcare reforms may have on our business, and no assurance can be given that any such reforms will not have a material adverse effect.identify alternative sources of drug product supply.

Manufacturing

Our initialcurrent manufacturing strategy is to outsourceevaluate each product candidate and determine which site in our manufacturing network provides the phase-appropriate technical, quality and regulatory compliance requirements. In addition, the long-range supply requirements of our product candidates are evaluated periodically to ensure we are planning manufacturing capacity and capabilities accordingly across our network. Our manufacturing network is comprised of our own laboratory facilities and the manufacturing packaging, labeling, storage,capabilities of our partners, including MSK and distribution for our preclinical studiesQ-Gen Cell Therapeutics, an affiliate of QIMR Berghofer, and clinical trials. In selecting contract manufacturing organizations or CMOs, to manufacture our product candidates, we generally strive to select(CMOs), including SAFC Carlsbad, Inc., FDB and CRL. This strategic approach provides us with the CMO based on the particular technical needs of the product candidate and quality and regulatory compliance. In addition, we aim to work with CMOs that possess the requisite scale, expertise and experienceflexibility to support our clinical and commercial production needs, address time or capacity constraints as well as commercial product manufacturing. We have transferred the manufacturing processes for tabelecleucel (formerly known as ATA129) from MSK to our CMO.  The transfer of manufacturing processes to our CMO includes modifications to the processes, improvements in the manufacturing process as well as product testing. Moreover, we are currently developing commercial-scale manufacturing processes for tabelecleucel for the Phase 3 trials, with the proposed dose and schedule to be used in clinical practice and at a cost sufficient to support profitable commercialization. In December 2017, following discussion with the FDA of manufacturing and comparability data generated on material manufactured by our contract manufacturing organization, we initiated these trials in the United States.provide supply redundancy, where appropriate.

We are building our own manufacturing facility, which is designed to support clinical production and ultimately commercialization of tabelecleucel, if approved.  In addition, we would expect our facility to support the supply needs for our other cellular therapy product candidates.  We would expect to maintain our relationships with our CMOs in order to have redundant sources of supply.  Our internal capabilities and experience in manufacturing encompass a broad range of activities including cell line development, process, analytical and formulation development, clinical and commercial scale GMP manufacturing, quality control and quality assurance. We are building the internal technical expertise in the manufacture of cellular therapeutics through hiring well experienced staff.  This breadth of experience will allow us to effectively oversee our own manufacturing facility as well as direct the activities of our contract manufacturers and testing facilities. Benefits of owning our own facility may include improved cost of goods, increased control and oversight of manufacturing and supply chain activities, greater control over maintenance and management of production capacity across multiple products, development of redundant supply capabilities to reduce risk, and reduced reliance on third parties.

Our T-cell product candidates require bloodblood-derived starting materials which are received from healthy, consenting third-partythird party donors through FDA- and EMA-compliant collection centers. Our manufacturing operations are conducted under Code of Federal Regulations Good Manufacturing Practices (GMPs), as starting materials. The manufacturing process involves co-culturing and incubating viral or cancer specific antigen transformed B-cells collected from the blood of third party-donors with T-cells collected from the same donor, all underwell as Good Tissue Practices or GTPs.(GTPs). GTPs are FDA regulations and guidance documents that govern the methods used in, and the facilities and controls used for, the manufacture of human cells, tissues and cellular and tissue based products, or HCT/Ps, which are human cells or tissue intended for implantation, transplant, infusion or transfer into a human recipient. The primary intent of the GTP requirements is to ensure that cell and tissue basedtissue-based products are manufactured in a manner designed to prevent the introduction, transmission and spread of communicable disease. FDA regulations also require tissue establishments to register and list their HCT/Ps with the FDA and, when applicable, to evaluate donors through screening and testing.

Pursuant toThrough agreements with our June 2015 license agreement with MSK,partners, we have acquired the right to use certain manufacturing process know-how related to producing clinical research-related drug supply. This includedThese include materials to support the manufacturing of clinical trialstudy material, including key starting materials and intermediates as well as existing inventory of clinical trialstudy materials. We have also entered into athe ability to obtain supply agreement with afrom third partyparties to ensure we have the necessary bloodstarting materials donated from healthy consenting third-partythird party donors.

Employees

Human Capital Management

As of February 15, 2018,December 31, 2023, we had 185 full-time225 employees, consistingexcluding those impacted by the reduction in force in November 2023, which was subsequently reduced by approximately 25% as a result of researchthe January 2024 reduction in force. We believe that the success of our business will depend, in part, on our ability to attract and development, regulatory affairs, technical operations, commercial operations, medical affairsretain qualified personnel. Our human capital strategy is designed to enable successful execution of our business objectives, while fostering a collaborative and general administrative functions.innovative culture, that embraces diversity and inclusion. We monitor our success with insights across human capital metrics such as employee engagement, vacancy rates, time to hire, promotion rates, performance ratings, succession depth, retention, EEO compliance, pay equity, and diversity representation. The principal purposes of our compensation policies and equity incentive plans are to attract, retain and motivate employees and directors by paying for performance through the granting of stock-based compensation awards and cash-based performance bonus awards. None of our employees are represented by a labor union or are a party to a collective bargaining agreement and we consider our relations with our employees to be good.

COVID-19 Business Update

To date, the COVID-19 pandemic has not materially impacted our or our partners’ clinical, research and development, regulatory, and manufacturing operations or timelines. We have transitioned a portion of our workforce to a remote, work-from-home

model, while maintaining essential in-person laboratory functions in order to advance key research, development and manufacturing priorities. We implemented safety protocols and procedures to support our onsite workforce.

The full extent to which the COVID-19 pandemic may impact our business and operations is subject to future developments which are uncertain and difficult to predict.

For additional information about risks and uncertainties related to the COVID-19 pandemic that may impact our business, financial condition and operations, see the section titled “1A. Risk Factors” under Part I, Item 1A in this Annual Report on Form 10‑K.

Corporate Information

We were incorporated in Delaware in 2012 and completed our initial public offering in October 2014.2012. Our principal corporate offices are located at 611 Gateway Blvd.2380 Conejo Spectrum St., Suite 900, South San Francisco, CA 94080200, Thousand Oaks, California 91320 and our telephone number at that address is (650) 278-8930.

Available Information

(805) 623-4211. Our website address is www.atarabio.com.

Available Information

We file Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K, proxy statements and other materials with the SEC.Securities and Exchange Commission (SEC). We are subject to the informational requirements of the Exchange Act and file or furnishmake these reports proxy statements, and other information with the SEC.  Such reports and other information filed by the Company with the SEC are available free of charge onthrough our website at investors.atarabio.com.

as soon as reasonably practicable after we electronically file such reports with, or furnish such reports to, the SEC. The public may also read and copyinformation contained on, or that can be accessed through, our website is not a part of or incorporated by reference in this Annual Report on Form 10-K or in any materials filed by Ataraother filings we make with the SEC at the SEC’s Public Reference Room at 100 F Street, NE, Room 1580, Washington, DC 20549.  The public may obtain information on the operation of the Public Reference Room by calling the SEC at 1-800-SEC-0330.  SEC.

The SEC also maintains a websitean internet site that contains reports, proxy and information statements and other information regarding issuers that file electronically with the SEC at www.sec.gov.

Item 1A. Risk Factors

Investing in our common stock involves a high degree of risk. YouInvestors should carefully consider all of the risk factors and uncertainties described below, in addition to the other information contained in this Annual Report on Form 10-K, including the section of this report titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and our consolidated and combined financial statements and related notes, before investing in our common stock.

The risks described below may not be the only ones relating to our company and additional risks that we currently believe are immaterial may also affect us. If any of the followingthese risks, including those described below, materialize, our business, competitive position, reputation, financial condition, and results of operations, cash flows and future prospects could be seriously harmed. In these circumstances, the market price of our common stocksecurities could decline, and youinvestors may lose all or a part of yourtheir investment.

Risks Related to Our Financial Results and Capital Needs

We have incurred substantial losses since our inception and anticipate that we will continue to incur substantial and increasing losses for the foreseeable future.

We are a clinical-stage biopharmaceutical company. Investment in biopharmaceutical product development is highly speculative because it entails substantial upfront capital expenditures and significant risk that a product candidatecandidates will fail to prove effective, gain regulatory approval or become commercially viable. We do not have any productsone product, Ebvallo, which is approved by regulatory authoritiesin the EU and the UK and have not generated anylimited revenues from product sales to date,commercialization, and have incurred significant research, development and other expenses related to our ongoing operations and expect to continue to incur such expenses. As a result, we have not been profitable and have incurred significant operating losses in every annual reporting period since our inception. For the year ended December 31, 2017,2023, we reported a net loss of $119.5 million and we had an accumulated deficit of $296.7 million as of December 31, 2017.$276.1 million.

We do not expectknow when, or if, we will generate sufficient revenue from commercialization to generate revenues for many years, if at all.offset our operating expenses. We expect to continue to incur significant expenses and operating losses for the foreseeable future. We anticipate these losses to increasefuture as we continue to research, develop and seek regulatory approvals for our product candidates and any additional product candidates we may acquire, and potentially begin to commercialize product candidates that may achieve regulatory approval.in-license or develop. We may encounter unforeseen expenses, difficulties, complications, delays and other unknown factors that may adversely affect our business. The size of our future net losses will depend, in part, on the rate of future growthchange of our expenses and our ability to generate revenues. If any of our product candidates fails in clinical trialsstudies or does not gain regulatory approval, or if approved, fails to achieve market acceptance, we may never become profitable. Even if we achieve profitability in the future, we may not be able to sustain profitability in subsequent periods. We anticipate that ourOur expenses willmay increase in the future as we continue to invest in research and development of our existing product candidates, investigate and potentially acquire new product candidates and expand our manufacturing and commercialization activities.candidates.

We have a limited operating history, which may make it difficult for you to evaluate the success of our business to date and to assess our future viability.

Our company was formed in August 2012. Our operations to date have been limited to organizing and staffing our company, acquiring product and technology rights and conducting product development activities for our product candidates. We have not yet demonstrated our ability to successfully complete any Phase 2 or Phase 3 clinical trials,studies, obtain regulatory approval in the U.S., consistently manufacture a commercial scale product or arrange for a third party to do so on our behalf, or conduct sales and marketing activities necessary for successful commercialization for any of our product candidates.candidates or arrange for a third party to do so on our behalf. In addition, the adoptive immunotherapy technology underlying our T-cell product candidates, including our next-generation CAR T programs, is new and largely unproven. Any predictions about our future success, performance or viability, particularly in view of the rapidly evolving cancer immunotherapy field, may notprove to be as accurate as they could be if we had a longer operating history or approved products on the market.inaccurate.

In addition, as a young business, we may encounter unforeseen expenses, difficulties, complications, delays and other known and unknown factors. We will need to transition at some point from a company with a research and development focus to a company capable of supporting commercial activities. We may not be successful in such a transition. We expect our financial condition and operating results to continue to fluctuate significantly from quarter to quarter and year to year due to a variety of factors, many of which are beyond our control. Accordingly, any of our quarterly or annual periods’ results are not indicative of future operating performance.

We currently have no source of revenues.earned limited commercialization revenues to date. We may never generate revenues or achieve profitability.

To date, we have not generated anyonly limited revenues from product sales or otherwise. Even if we are able to successfully achievecommercialization. We have regulatory approval for ourone product, candidates,Ebvallo, in the EU and the UK. We have out-licensed the commercialization rights to tab-cel (Ebvallo in the EU and the UK) to Pierre Fabre under the A&R Commercialization Agreement and we do not know when we will generate revenues or become profitable, if at all.have sold certain royalty and milestone interests for the Initial Territory, subject to a specified cap, to HCRx pursuant to the HCRx Agreement. Our ability to generate revenues from product salescommercialization and achieve profitability will be subject to the A&R Commercialization Agreement, the HCRx Agreement and depend on our commercialization partners’ ability to successfully commercialize products, including any of our current product and product candidates, and other product candidates that we may develop, in-license or acquire in the future. Our ability to generate revenues from the sale of products and achieve profitability will also dependsdepend on a number of additional factors, including our ability to:

Our revenues forfrom Ebvallo or any product candidate for which regulatory approval is obtained will be dependent, in part, upon the size of the markets in the territories for which we gain regulatory approval, the accepted price for the product, the ability to get reimbursement at any price, and whether we own the commercial rightsterms and conditions of our commercialization agreement with our partner for that territory. We do not retain any meaningful milestones or royalty payments from Pierre Fabre for Ebvallo in the Initial Territory until the applicable royalty cap under the HCRx Agreement is met, which could take many years, if at all. If the number of our addressable disease patients is not as significant as we estimate, the indication approved by regulatory authorities is narrower than we expect, or the reasonably accepted population for treatment is narrowed by competition, physician choice, or treatment guidelines weor a reduction in the incidence of the addressable disease, our partners may not generate significant revenues from sales of suchsuccessfully commercialize our products, even if approved. In addition,The timing and amount of any milestone and royalty payments we anticipate incurring significant costs associated with commercializing any approved product candidate.may receive from our partners, as well as the commercial success of our products will depend on, among other things, the efforts, allocation of resources, negotiation of pricing and reimbursement and successful commercialization of our products by our partners. As a result, even if we generate product revenues, we may not become profitable and may need to obtain additional funding to continue operations. If we fail to become profitable or are unable to sustain profitability on a continuing basis, then we may be unable to continue our operations at planned levels and may be forced to reduce our operations.

We will require substantial additional financing on terms acceptable to us to achieve our goals, and a failure to obtain this necessary capital when needed could force us to delay, limit, reduce or terminate our product development or commercializationmanufacturing efforts.

We expect to expend substantial resources for the foreseeable future to continue the clinical development and manufacturing of our T-cell immunotherapy product candidates, and the advancement and expansion of our preclinical research pipeline. We also expect to continue to expend resources for the development and manufacturing of our product and product candidates and the technology we have licensed or have an exclusive right to license from QIMR Berghofer, including ATA188 and ATA190, which are in development for the treatment of MS.our partners. These expenditures will include costs associated with research and development, potentially acquiring or licensing new product candidates or technologies, conducting preclinical studies and clinical trialsstudies and potentially obtaining regulatory approvals and manufacturing products, as well as marketing and selling products approved for sale, if any.products. Under the terms of our license agreements with each of MSK and QIMR Berghofer,our in-license partners, we are obligated to make payments upon the achievement of certain development, regulatory and commercial milestones. In addition, other unanticipated costs may arise. Because the design and outcome of our ongoing, planned and

anticipated clinical trialsstudies is highly uncertain, we cannot reasonably estimate the actual amounts necessary to successfully complete the development and commercialization of our product and product candidates.

Our future capital requirements depend on many factors, including:

We believeexpect that our existing cash, cash equivalents and short-term investments, combined with certain anticipated payments from the A&R Commercialization Agreement, as well as cost reductions from completed workforce reductions and operating efficiencies resulting from our planned transition of substantially all activities relating to tab-cel at the time of the BLA transfer to Pierre Fabre, will be sufficientenable us to fund our planned operations into 2027. Such anticipated payments are estimates based on assumptions and plans that are subject to change and such changes could materially impact our cash runway. These assumptions include the first halfreceipt of 2020. Asfuture payments that are dependent upon the successful filing and approval of December 31, 2017, we had total cash, cash equivalentsthe tab-cel BLA, as well as the completion of specific development and short-term investments of $166.1 million,regulatory activities by us and in January 2018, we completed an underwritten public offering, resulting in net proceeds to us of approximately $131.4 million. However, ouractions taken by third parties, and are, therefore, uncertain at this time.

Our operating plan may change as a result of many factors currently unknown to us, and we may need additional funds sooner than planned. In addition, we may seek additional capital due to favorable market conditions or strategic considerations even if we believe we have sufficient funds for our current or future operating plans. We do not have any committed external source of funds. Additional funds other than milestone and royalty payments that we may receive under the A&R Commercialization Agreement, subject to the terms of the HCRx Agreement. We do not retain any meaningful milestone or royalty payments related to the Initial Territory from Pierre Fabre until the applicable royalty cap under the HCRx Agreement is met, if at all.

As of December 31, 2023, we had total cash, cash equivalents and short-term investments of $51.7 million. Our existing cash, cash equivalents and short-term investments as of December 31, 2023 will not be available whensufficient to fund our planned operations for at least the next twelve months from the date of issuance of these financial statements. These conditions raise substantial doubt about our ability to continue as a going concern for at least 12 months after the issuance of the accompanying consolidated financial statements.

To alleviate the conditions that raise substantial doubt about our ability to continue as a going concern, we plan to secure additional capital, potentially through a combination of public or private security offerings; use of our ATM facility; and/or strategic transactions. We may also need themto raise additional funding as required based on the status of our development programs and our projected cash flows. Although we have been successful in raising capital in the past, and expect to continue to raise capital as required, there is no assurance that we will be successful in obtaining sufficient funding on terms that are acceptable to us to fund continuing operations, if at all, or at all.identify and enter into any strategic transactions that will provide the capital that we will require. If adequate fundswe are not availableunable to usobtain sufficient funding on a timely basis,acceptable terms, we maycould be requiredforced to delay, limit, reduce or terminate preclinical studies, clinical trialsstudies or other development activities for one or more of our product candidates, or delay, limit, reduce or terminatewhich could have a material adverse effect on our establishmentbusiness, results of salesoperations, and marketing capabilities or other activities that may be necessary to commercialize our product candidates.financial condition.

Raising additional capital may cause dilution to our existing stockholders, restrict our operations or require us to relinquish rights to our product candidates on terms that are unfavorable terms to us.

We mayplan to seek required additional capital, and may do so through a variety of means, including through private and public equity offerings and debt financings. For example, in December 2022, we sold certain of our royalty and milestone interests related to the Initial Territory under the amended and restated Pierre Fabre Commercialization Agreement, subject to a specified cap, to HCRx pursuant to the HCRx Agreement. To the extent that we raise additional capital through the sale of equity or convertible debt securities, youror if existing holders of warrants exercise their rights to purchase common stock, the ownership interest of existing

stockholders will be diluted, and the terms may include liquidation or other preferences that adversely affect yourthe rights of stockholders. To the extent equity valuations, including the trading price of our common stock, are depressed as a stockholder.result of economic disruptions or other uncertainties, for example due to rising inflationary pressures, the war in Ukraine, the war in the Middle East or other factors, the potential magnitude of this dilution will increase. Debt financing, if available, may involve agreements that include covenants limiting or restricting our ability to take certain actions, such asincluding incurring additional debt, making capital expenditures, entering into licensing arrangements, or declaring dividends. If we raise additional funds from third parties, we may have to relinquish valuable rights to our technologies or product candidates or grant licenses or other rights on terms that are not favorable to us. If we are unable to raise additional funds through equity or debt financing when needed, we may be required to delay, limit, reduce or terminate our product development or commercialization efforts for our product candidates, or grant to others the rights to develop and market product candidates that we would otherwise prefer to develop ourselves or take other actions that are adverse to our business.

If we fail to continue to meet the listing standards of Nasdaq, our common stock may be delisted, which could have a material adverse effect on the liquidity of our common stock.

Our common stock is currently listed on the Nasdaq Global Market. Nasdaq has requirements that a company must meet in order to remain listed on Nasdaq. In particular, Nasdaq rules require us to maintain a minimum bid price of $1.00 per share of our common stock (the “Bid Price Requirement”). If the closing bid price of our common stock falls below $1.00 per share for 30 consecutive trading days or we do not meet other listing requirements, we would fail to be in compliance with Nasdaq listing standards. There can be no assurance that we will continue to meet the Bid Price Requirement, or any other requirement in the future.

On January 8, 2024, we received a deficiency letter from the Listing Qualifications Department of Nasdaq notifying us that, for the last 30 consecutive business days, the bid price for our common stock had closed below the Bid Price Requirement.

In accordance with Nasdaq Listing Rule 5810(c)(3)(A) (Compliance Period Rule), we have been provided a period of 180 calendar days, or until July 8, 2024 (Compliance Date), to regain compliance with the Bid Price Requirement. If, at any time before the Compliance Date, the bid price for our common stock closes at $1.00 or more for a minimum of 10 consecutive business days, as required under the Compliance Period Rule, Nasdaq will provide us written communication that we have regained compliance with the Bid Price Requirement.

If we do not regain compliance with the Bid Price Requirement by the Compliance date, we may be eligible for an additional 180 calendar day compliance period. To qualify, we will be required to (i) transfer to the Nasdaq Capital Market, (ii) provide written notice of our intention to cure the deficiency during the additional 180 calendar day compliance period, by effecting a reverse stock split, if necessary, and (iii) and meet the continued listing requirement for market ourselves.value of its publicly held shares and all other initial listing standards for the Nasdaq Capital Market, with the exception of the Bid Price Requirement, which requirements include, among other things, a minimum stockholders’ equity of at least $4 million. For the year ended December 31, 2023, we reported total stockholders’ deficit of $99.2 million, which is below the stockholders’ equity requirement under the applicable standards.

If we do not regain compliance with the Bid Price Requirement by the Compliance Date and we are not eligible for an additional compliance period, or Nasdaq concludes that we will not be able to cure the deficiency during the additional compliance period, Nasdaq will provide us written notification that our common stock will be subject to delisting. At that time, we may appeal the delisting determination to a Nasdaq Hearings Panel. However, there can be no assurance that such appeal would be successful. If the Nasdaq Hearing Panel does not result in Nasdaq granting us an extension of time to achieve compliance with the Minimum Bid Price Rule, our common stock will be delisted from Nasdaq.

If our common stock were to be delisted, the actual and potential liquidity of our common stock and our ability to raise future capital would be adversely affected and the market price of our common stock could decrease. If, for any reason, we are unable to obtain listing on another national securities exchange or take action to restore our compliance with Nasdaq’s continued listing requirements, a reduction in some or all of the following may occur, each of which could have a material adverse effect on our stockholders:

● the number of broker-dealers willing to execute trades in shares of our common stock

Our workforce reductions may not result in anticipated savings, could result in total costs and expenses that are greater than expected and could disrupt our business.

In August 2022, we reduced our workforce by approximately 20% across all areas of our company, including members of management. In November 2023, we further reduced our workforce by approximately 30%. In January 2024, we announced another reduction of our workforce by approximately 25%. The reductions in force reflect a prioritization around key research and development programs and the reduction of our expense profile. We may not realize, in full or in part, the anticipated benefits, savings and improvements in our cost structure from our restructuring efforts due to unforeseen difficulties, delays or unexpected costs. If we are unable to realize the expected operational efficiencies and cost savings from restructuring, our operating results and financial condition would be adversely affected. We also cannot be certain that we will not have to undertake additional workforce reductions or restructuring activities in the future. Furthermore, our cost savings plan may be disruptive to our operations, which could affect our ability to generate product revenue. In addition, our workforce reductions could yield unanticipated consequences, such as attrition beyond planned staff reductions, or disruptions in our day-to-day operations. Our workforce reductions could also harm our ability to attract and retain qualified management, scientific, clinical, and manufacturing personnel who are critical to our business. Any failure to attract or retain qualified personnel could prevent us from successfully developing and commercializing our product candidates in the future, including tab-cel, if approved.

There can be no assurance that we will achieve all of the anticipated benefits of the Fujifilm Transaction and we could face unanticipated challenges.

We may not realize some or all of the anticipated benefits from the Fujifilm Transaction and we may encounter post-closing risks, including associated with the provision of services to us by FDB pursuant to the Fujifilm MSA. We may experience increased difficulty and loss of institutional knowledge as a result of the transfer of ATOM Facility employees to FDB in connection with the Fujifilm Transaction, which could harm our business. Additionally, significant time and resources may be required from us, which could disrupt our business and distract management from other responsibilities, which may result in losses or continued financial involvement in the ATOM Facility, including through indemnification or other financial arrangements, which could adversely affect our financial results.

Risks Related to the Development of Our Product and Product Candidates

We have one approved product, Ebvallo, in the EU and the UK and are verygenerally early in our development efforts and have only a small number of product candidates in clinical development. All of our other product candidates are still in preclinical development. If we or our collaborators are unable to successfully develop, manufacture and commercialize our product or product candidates or experience significant delays in doing so, our business may be materially harmed.

We have one approved product, Ebvallo, in the EU and the UK and are verygenerally early in our development efforts, and only a small number of our product candidates are in clinical development. AllThe majority of our other product candidates are currently in preclinical development. We have invested substantially all of our efforts and financialsubstantial resources in identifying and developing potential product candidates, and conducting preclinical and clinical studies, clinical trialsmanufacturing activities, and manufacturing activities.preparing for the commercial launch of our product and product candidates. Our ability to generate revenues which we do not expect will occur for many years,from the sale of our product and product candidates, if ever,approved, will depend heavily on the successful development, manufacture and our partners' eventual commercialization of our product and product candidates.

The success of our product and product candidates will depend on severalmany factors, including the following:

If we do not achieve one or more of these factors in a timely manner or at all, we could experience significant delays or an inability to successfully develop and commercialize our product candidates, which could materially harm our business.

We have been affected by and could be adversely affected in the future by the effects of health epidemics and pandemics, including the COVID-19 pandemic, which could materially and adversely affect our business and operations in the future, as well as the businesses and operations of third parties on which we rely.

Our business could be adversely affected by health epidemics and pandemics, including the COVID-19 pandemic, which presented a substantial public health and economic challenge around the world and has affected, and continues to affect, our employees, patients, communities and business operations, as well as the U.S. economy and financial markets. We continue to maintain essential in-person manufacturing and laboratory functions in order to advance key research, development and manufacturing priorities. In connection with these measures, we may be subject to claims based upon, arising out of, or related to COVID-19 and our actions and responses thereto. The effects of potential future state executive orders, local shelter-in-place orders, government-imposed quarantines, our work-from-home policies and other similar actions may negatively impact productivity, disrupt our business and delay our clinical programs and timelines, the magnitude of which will depend, in part, on the length and severity of the restrictions and other limitations on our ability to conduct our business in the ordinary course.

Further quarantines, shelter-in-place or similar restrictions and other actions taken by foreign, federal, state and local governments, or the perception that such orders, shutdowns or other restrictions on the conduct of business operations could be reinstated, related to COVID-19, other health epidemics and pandemics, or other infectious diseases, could impact our manufacturing capabilities and third party manufacturing facilities in the United States and other countries, or the availability or cost of materials, which would disrupt our supply chain. In particular, standard transportation channels were impacted and may again be impacted, and we and other manufacturing, testing, product disposition, CMOs and external testing laboratories are subject to enhanced risk assessment and mitigation measures. In addition, there were and may continue to be interruptions in the supply of leukapheresis collections, which supply raw materials used in our products.

Our clinical trials may also be affected by health epidemics and pandemics and have been affected by the COVID-19 pandemic. Clinical site initiation and patient enrollment experienced delays as a result of the COVID-19 pandemic, including due to the prioritization of hospital resources toward COVID-19 and away from clinical trials and as a result of changing practice patterns that impact the diseases our trials address. Some patients may not be able to comply with clinical trial protocols if quarantines impede patient movement or interrupt healthcare services or if patients are forced to quarantine due to a health epidemic or pandemic. For example, while most clinical trial sites for our studies, including our Phase 3 clinical trial of tab-cel in patients with EBV+ PTLD, remained open to enrollment for patients, some sites limited the screening and enrollment of new patients due to governmental orders related to COVID-19, or fear of infection of COVID-19, limited, and may limit in the future, patients’ abilities to access clinical sites. Pandemic-related travel restrictions may also interrupt key clinical trial activities, such as clinical trial site data monitoring and the collection, processing and analyses of efficacy, safety and translational data. For example, at the outset of the COVID-19 pandemic, we observed a temporary slow-down in stem cell and solid organ transplant volumes, which may have decreased the eligible patient population for the tab-cel Phase 3 study. In April 2020, we initiated a temporary pause in the screening and enrollment of patients in our EMBOLD study of ATA188 in patients with PMS. Although we were able to resume the screening and enrollment of patients in our EMBOLD study and enrolled the first patient in the study in June 2020, the COVID-19 pandemic required us to pause screening and enrollment of patients in our clinical studies. Similarly, our ability to recruit and retain principal investigators and site staff who, as healthcare providers, may have heightened exposure to health epidemics and pandemics, may be adversely impacted.

In addition, to the extent the COVID-19 pandemic adversely affected our business and results of operations, it may also have the effect of heightening many of the other risks and uncertainties described elsewhere in this “Risk Factors” section.

Our future success is dependent on the regulatory approval of our product candidates.

We do notonly have any productsone product, Ebvallo, that havehas gained regulatory approval.approval, an approval in the EU and the UK. Currently, our onlyprioritized clinical-stage product candidates are tabelecleucel (formerly known as ATA129), for which we recently initiated Phase 3 clinical trialsinclude tab-cel (tabelecleucel) in the United States, ATA188, which is in a Phase 1 clinical trial, ATA190, which is in a Phase 1 clinical trial conducted by QIMR Berghofer,U.S. and ATA230, which is in Phase 2 clinical trials.ATA3219 Our business is substantially dependent on our ability to obtain regulatory approval for, and, if approved, to find a partner who can successfully commercialize our product candidates in a timely manner. We cannot

Neither we nor our partners can commercialize product candidates in the United StatesU.S. without first obtaining regulatory approval for the product candidates from the FDA; similarly, neither we cannotnor our partners can commercialize product candidates outside of the United StatesU.S. without obtaining regulatory approval from comparable foreign regulatory authorities. Before obtaining regulatory approvals for the commercial sale of any product candidate for a target indication, we must demonstrate with substantial evidence gathered in preclinical studies and clinical trials, generally including two well-controlled Phase 3 trials,studies that the product candidate is safe and effective for use for that target indication and that the manufacturing facilities, processes and controls are adequate with respect to such product candidate.candidate to assure stability, safety, purity and potency.

The time required to obtain approval by the FDA and comparable foreign regulatory authorities is unpredictable but typically takes many years following the commencement of preclinical studies and clinical trialsstudies and depends upon numerous factors, including the substantial discretion of the regulatory authorities. The novel nature of our product candidates may create further challenges in obtaining regulatory approval. For example, the FDA and comparable foreign regulatory authorities have limited experience with regulating the development and commercialization of T-cell immunotherapies, particularly allogeneic T-cell product candidates, and CAR T therapies, including assessing the comparability of different versions of such product candidates. In addition, approval policies, regulations, regulatory positions or the type and amount of clinical and other data necessary to gain approval may change during the course of a product candidate’s clinical development and throughout regulatory interactions, and may vary among jurisdictions.jurisdictions, particularly for novel therapies. The EC and the MHRA has approved the MAA for Ebvallo as a monotherapy treatment for patients with EBV+ PTLD who have received at least one prior therapy under “exceptional circumstances,” which is a pathway under which EC and MHRA grant marketing authorization when “comprehensive data cannot be obtained even after authorization.” Under the exceptional circumstances marketing authorization, our commercial partner, Pierre Fabre, is subject to ongoing post-marketing obligations to continue confirmation of the benefits of Ebvallo, and if any of our other product candidates are approved under this pathway, we or our future commercial partners will be subject to this obligation. Continuation of the Ebvallo marketing authorization is subject to annual re-assessment. The annual re-assessment will determine whether the Ebvallo marketing authorization should be maintained, changed, or suspended, based on Pierre Fabre’s fulfillment of post-marketing obligations and the risk/benefit profile of Ebvallo. If we, or our commercial partners, do not satisfy the ongoing post-marketing obligations or the EC determines that the risk/benefit profile of Ebvallo is not acceptable, the EC may change or suspend the marketing approval for Ebvallo. We have not obtained regulatory approval for any other product candidate, and it is possible that none of our existing product candidates or any future product candidates will ever obtain regulatory approval.

Our product candidates could fail to receive regulatory approval from the FDA or a comparable foreign regulatory authority for many reasons, including:

The FDA or a comparable foreign regulatory authority may require more information beyond what we plan to provide in or expect to be required for a marketing application, including additional CMC information, preclinical or clinical data to support approval, whichapproval. These requirements may delay or prevent approval and our commercialization plans, or we may decide to abandon the development program. For example, at a Type B meeting in February 2022, we were not able to align with the FDA on comparability between tab-cel product versions used in the pivotal ALLELE study and the intended commercial product. The FDA initially recommended we conduct a new clinical trial with the commercial product to address the lack of alignment on comparability and to gain additional clinical experience with the intended commercial product. Throughout 2023, we held a number of meetings with the FDA on clinical aspects and CMC for a potential BLA submission for tab-cel. We recently held a pre-BLA meeting with the FDA that supports our plan to submit the tab-cel BLA in the second quarter of 2024. The FDA may not ultimately accept or approve a BLA submission with the current clinical dataset. In this case, the conduct of an additional clinical trial or trials in the lead indication or completing the ongoing ALLELE study may be necessary to support a BLA submission for tab-cel, which would result in considerable delay to a BLA submission or could lead us not to pursue a BLA submission. Conducting an additional clinical trial, if required, may prove too difficult or too expensive, and the process of designing a clinical trial, enrolling enough patients, and completing treatment and data collection under the protocol could take a significant amount of time, effort, and resources. Even if we complete the clinical trial, the study may not meet its prespecified endpoints, and even if it does, the FDA may still disagree that the clinical trial is sufficient to support submission and approval of a BLA for tab-cel, or may consider that the data, while adequate for BLA submission, can support only a more limited indication than that for which we initially applied.

Our development activities and/or commercialization planning with our partners could be harmed or delayed by governmental or regulatory delays due to a variety of factors. These factors include limitations on the availability of governmental and regulatory agency personnel to review regulatory filings or engage with us (caused by global health concerns or otherwise, including the COVID-19 pandemic); changes to governmental regulatory requirements, policies, guidelines or priorities, reallocation, or availability of government resources; or for other reasons, that may significantly delay the FDA’s, or other regulatory agencies', ability to review and process any submissions we have filed or may file or cause other regulatory delays. If global health concerns continue to prevent the FDA or other regulatory authorities from conducting their regular inspections, or impact reviews or other regulatory activities, it could significantly impact the ability of the FDA or other regulatory authorities to review and process our regulatory submissions in a timely fashion, which could have a material adverse effect on our business. For example, in response to the COVID-19 pandemic, on March 10, 2020, the FDA announced its intention to postpone most inspections of foreign manufacturing facilities and products inspections of domestic manufacturing facilities through April 2020. On March 18, 2020, the FDA announced its intention to postpone temporarily routine surveillance inspections of domestic manufacturing facilities and provided guidance regarding the conduct of clinical trials. On July 10, 2020, the FDA announced that it is working toward the goal of restarting on-site inspections it deems to be “mission critical.” In May 2021, the FDA updated its guidance, first published in August 2020, clarifying how it intends to conduct inspections during the COVID-19 pandemic, including how it plans to determine which inspections are “mission critical.” Additionally, on April 14, 2021, the FDA issued a guidance document in which the FDA described its plans to conduct voluntary remote interactive evaluations of certain drug manufacturing facilities and clinical research sites. According to the guidance, the FDA intends to request such remote interactive evaluations in situations where an in-person inspection would not be prioritized, deemed mission-critical, or where direct inspection is otherwise limited by travel restrictions, but where the FDA determines that remote evaluation would still be appropriate. The FDA intends to use this risk-based assessment system to identify the categories of regulatory activity that can occur within a given geographic area, ranging from mission critical inspections to resumption of all regulatory activities. The FDA has since adjusted its inspection activities in response to the COVID-19 pandemic. On December 29, 2021, the FDA implemented temporary changes to its inspection activities to ensure the safety of its employees and regulated firms. On February 2, 2022, FDA announced that it would resume domestic surveillance inspections across all product areas on February 7, 2022. In July 2022, FDA published draft guidance outlining its policies regarding remote regulatory assessments. On May 11, 2023, the COVID-19 Public Health Emergency (PHE) declared under the Public Health Services (PHS) Act expired. It is unclear how FDA’s and other health agencies’ policies and guidance will impact any inspections of our facilities or clinical trial sites involved with our clinical studies.

If we were todo obtain approval for a product candidate marketing application, regulatory authorities may approve any of our product candidates for fewer or more limited indications than we request (including failing to approve the most commercially promising

indications), may grant approval contingent on the performance of costly post-marketing clinical trials,studies, or may approve a product candidate with a label that does not include the labeling claims necessary or desirable for the successful commercialization of that product candidate.

In addition, the clinical study requirements of the FDA, EMA and other regulatory agencies and the criteria these regulators use to determine the safety and efficacy of a product candidate are determined according to the type, complexity, novelty and intended use and market of the potential products. The regulatory approval process for novel product candidates, such as our novel T-cell product candidates and next-generation CAR T programs, can be more complex and consequently more expensive and take longer than for other, better known or extensively studied pharmaceutical or other product candidates. Approvals by the EC and FDA of autologous CAR T therapies, such as Novartis’ Kymriah® and Gilead’s Yescarta®, may not be indicative of what these regulators may require for approval of our therapies. We have multiple clinical trials of our product candidates currently ongoing. If an adverse safety issue, clinical hold or other adverse finding occurs in one or more of our clinical trials, such event could adversely affect our other clinical trials of the same or related product candidates. Moreover, our product candidates may not perform successfully in clinical studies or may be associated with adverse events that distinguish them from those that have previously been approved, such as approved autologous CAR T therapies. For instance, allogeneic product candidates may result in adverse events not experienced with autologous products. Even if a product candidate were to successfully obtain approval fromis approved by the FDA and comparable foreign regulatory authorities, anythe approval might contain significant limitations related to use restrictions for specified age groups, warnings, precautions or contraindications, or may be subject to burdensome post-approval study or risk management requirements. If we are unable to obtain regulatory approval for one of our product candidates in one or more jurisdictions, or any approval contains significant limitations, we may not be able to obtain sufficient funding to continue the development of that product or generate revenues attributable to that product candidate. Also, any regulatory approval of our current or future product candidates, once obtained, may be withdrawn.withdrawn in a region or country by the respective regulatory agency.

Our T-cell immunotherapy product and product candidates and our next-generation CAR T programs represent new therapeutic approaches that could result in heightened regulatory scrutiny, delays in clinical development or delays in or our inability to achieve regulatory approval, commercialization or commercializationpayor coverage of our product candidates.

Our future success is dependent on the successful development and commercialization of T-cell immunotherapies and our next-generation CAR T programs in general and our development product candidates in particular. Because these programs, particularly our pipeline of allogeneic T-cell product and product candidates that are bioengineered from donors, represent a new approach to immunotherapy for the treatment of cancer and other diseases, developing and commercializing our product candidates subject us to a number of challenges, including:

We cannot be sure that the manufacturing processes used in connection with our T-cell immunotherapy product and product candidates will yield a sufficient supply of satisfactory products that are stable, safe, pure, and effective,potent, or comparable to those T-cellsT cells historically produced by MSK or QIMR Berghofer historically,our partners, be scalable or profitable.

Moreover, actual or perceived of safety issues, including adoption of new therapeutics or novel approaches to treatment, may adversely influence the willingness of subjects to participate in clinical trials,studies, or, if one of our product candidates is approved by applicable regulatory authorities, of physicians to subscribe to the novel treatment mechanics.mechanics or of patients to provide consent to receive a novel treatment despite its regulatory approval. The FDA or other applicable regulatory authorities may require specific post-market studies or additional information that communicates the benefits or risks of our products. New data may reveal new risks of our product candidates at any time prior to or after regulatory approval.

The FDA may also modify or enhance trial requirements which may affect enrollment. In August 2023, the FDA published a guidance document, Informed Consent, Guidance for IRBs, Clinical Investigators, and Sponsors, which supersedes past guidance and finalizes draft guidance on informed consent. The FDA’s new guidance presents evolving requirements for informed consent which may affect recruitment and retention of patients in clinical trials. Effects on recruitment and retention of patients may hinder or delay a clinical trial and could cause a significant setback to an applicable program.

Physicians, hospitals and third-partythird party payors often are slow to adoptutilize new products, technologies and treatment practices that require additional upfront costs and training. Physicians may not be willing to undergo training to adopton this novel therapy, may decide the therapy is too complex to adopt without appropriate training or not cost-efficient, and may choose not to administer the therapy. Based on these and other factors, hospitals and payors may decide that the benefits of this new therapy do not or will not outweigh its costs.

The results of preclinical studies or earlier clinical trialsstudies are not necessarily predictive of future results. Our existing product candidates in clinical trials,studies, and any other product candidate we advance into clinical trials,studies, may not have favorable results in later clinical trialsstudies or receive regulatory approval.

Success in preclinical studies and early clinical trialsstudies does not ensure that later clinical trialsstudies will generate adequate data to demonstrate the efficacy and safety of an investigational drug. ALikewise, a number of companies in the pharmaceutical and biotechnology industries, including those with greater resources and experience than us, have suffered significant setbacks in clinical trials,studies, even after seeing promising results in earlier preclinical studies or clinical trials. For example, in December 2015, we announced that our Phase 2 proof-of-concept trial of PINTA 745 did not meet its primary endpoint even though earlier clinical trials and preclinical studies had indicated that it might be effective to treat protein energy wasting in patients with end stage renal disease.studies. Despite the results reported in earlier preclinical studies or clinical trialsstudies for our product candidates, wethere can be significant variability in safety and efficacy results between different clinical trials of the same product candidate due to numerous factors. We do not know whether the clinical trialsstudies we may conduct, or clinical studies in progress, will demonstrate adequate efficacy and safety to result in regulatory approval to market tabelecleucel, ATA520, ATA188, ATA190, ATA230 or any of our other product candidates in any particular jurisdiction. Tabelecleucel

Tab-cel has been predominantly evaluated in a single-center trialstudies under investigator-sponsored INDsinvestigational new drug (INDs) applications held by MSK and in our Expanded Access Programs, utilizing a different response criteria and endpoints from those we have used or may utilize in later clinical trials. For example, the primary endpoint of both the MATCH and ALLELE trials is confirmed best objective response rate defined as the percent of patients achieving either a complete or partial response to treatment with tabelecleucel confirmed after the initial tumor assessment showing a response. In contrast, the prior MSK trials did not include response confirmation. The findings may not be reproducible in multi-center trials we conduct. For regulatory approvals, we are using independent radiologist and/or oncologist assessment of responses which may not correlate with the MSK reported assessments. In addition, thestudies. These Phase 2 clinical trialsstudies with tabelecleuceltab-cel also enrolled a heterogeneous group of patients with a variety of EBV-associatedEBV-driven malignancies, including but not limited to EBV+ PTLD after HCT and EBV+ PTLD after SOT. These Phase 2 trialsstudies were not prospectively designed to evaluate the efficacy of tabelecleuceltab-cel in the treatment of a single disease state for which we may later seek approval. Findings from early studies may not be reproducible in late phase studies we conduct. For instance, the current protocol for our ALLELE study in EBV+ PTLD is designed to rule out a 20% ORR as the null hypothesis. This means that if the lower bound of the 95% confidence interval on ORR among patients receiving at least one dose of tab-cel exceeds 20% at the end of the study, then the study would be expected to meet the primary endpoint for the treatment of PTLD. For example, assuming enrollment of 33 patients in a cohort of ALLELE, an observed ORR above approximately 37% would be expected to meet the primary endpoint for that cohort. In addition, our amended ALLELE study protocol includes an interim analysis as well as a final study analysis. We have previously received feedback from the FDA that an interim analysis of the ALLELE study may not be sufficient to support approval of a BLA. Moreover, final trialstudy results may not be consistent with interim trialstudy results. Furthermore, modifications to the total sample size of the ALLELE study and the statistical approach may be necessary in connection with the review of such a BLA submission by the FDA.

Efficacy data from prospectively designed trialsstudies may differ significantly from those obtained from retrospective subgroup analyses. In addition, clinical data obtained from a clinical trialstudy with an autologousallogeneic product candidate may not yield the same or better results withas compared to an allogeneicautologous product candidate. If later-stage clinical trialsstudies do not produce favorable results, our ability to achieve regulatory approval for any of our product candidates may be adversely impacted. Even if we believe that we have adequate data to support an application for regulatory approval to market any of our product candidates, the FDA or other regulatory authorities may not agree and may require that we conduct additional clinical trials.studies.

Ebvallo was approved under the exceptional circumstances regulatory pathway by the EMA and the MHRA, therefore continuation of the Ebvallo marketing authorizations in the EU and the UK are subject to annual reassessments. The annual reassessments will determine whether the Ebvallo marketing authorization should be maintained, changed, or suspended, based on Pierre Fabre’s fulfillment of post-marketing obligations and the risk/benefit profile of Ebvallo.

Interim “top line” and preliminary data from clinical studies that we or our partners may announce or share with regulatory authorities from time to time may change as more patient data become available and are subject to audit and verification procedures that could result in material changes in the final data.

From time to time, we or our partners may announce or share with regulatory authorities interim “top line” or preliminary data from clinical studies. Interim data from clinical studies are subject to the risk that one or more of the clinical outcomes may materially change as patient enrollment continues and more patient data become available. Preliminary or “top line” data also remain subject to audit and verification procedures that may result in the final data being materially different from the preliminary data previously announced. As a result, interim and preliminary data should be viewed with caution until the final data are available. Adverse differences between preliminary or interim data and final data could impact the regulatory approval of, and significantly harm the prospects of any product candidate that is impacted by the applicable data.

Clinical drug development involves a lengthy and expensive process with an uncertain outcome.

Clinical testing is expensive and can take many years to complete, and its outcome is inherently uncertain. Failure can occur at any time during the clinical trialstudy process. Product candidates in later stages of clinical trialsstudies may fail to show the desired safety and efficacy traits despite having progressed through preclinical and clinical trials.studies.

We may experience delays in our ongoing or future clinical trialsstudies and we do not know whether planned clinical trialsstudies will begin or enroll subjects on time, will need to be redesigned or will be completed on schedule, if at all. There can be no assurance that the FDA or comparable foreign regulatory authorities will not put clinical trialsstudies of any of our product candidates on clinical hold in the future. Clinical trialsstudies may be delayed, suspended or prematurely terminated for a variety of reasons, such as:

Patient enrollment, a significant factor in the timing of clinical trials,studies, is affected by many factors including including:

As an example, we activated additional clinical sites for the ALLELE study of tab-cel over the course of 2018 and increased HLA coverage during this period. As a result, enrollment in our studies was limited in the early part of 2018 and increased through the course of the year as we increased clinical sites and HLA coverage. However, in May 2019, we announced that enrollment in our Phase 3 studies of tab-cel for patients with EBV+ PTLD was proceeding slower than anticipated. Many of our product candidates are designed to treat rare diseases, and as a result, the pool of potential patients with respect to a given disease is small. We may not be able to initiate or continue to support clinical trialsstudies of tabelecleucel, ATA188, ATA520, ATA230tab-cel or any futureother product candidates if we are unable to locate and enroll a sufficient number of eligible participants in these trialsstudies as required by the FDA or other regulatory authorities. We experienced some transient delays in clinical trial site initiation and patient enrollment in certain of our clinical trials, including our ALLELE study, as a result of the COVID-19 pandemic. Even if we are able to enroll a sufficient number of patients in our clinical trials,studies, if the pace of enrollment is slower than we expect, the development costs for our product candidates may increase and

the completion of our trialsstudies may be delayed or our trialsstudies could become too expensive to complete.

We rely on CROs, other vendors and clinical trialstudy sites to ensure the proper and timely conduct of our clinical trials,studies, and while we have agreements governing their committed activities, we have limited influence over their actual performance. Furthermore, these third parties may also have relationships with other entities, some of which may be our competitors. Reliance on CROs entails risks to which we would not be subject if we conducted our clinical studies ourselves, including reliance on the CRO for clinical site initiation and monitoring, the possibility that the CRO does not maintain the financial resources to meet its obligations under our agreements, the possibility of breach of these agreements by the CRO because of factors beyond our control, including a failure to properly perform their obligations under these agreements, and the possibility of termination or non-renewal of the agreements by the CROs, based on their own business priorities, at a time that is costly or damaging to us. Our reliance on these third parties for research and development activities will reduce our control over these activities but will not relieve us of our regulatory responsibilities. For example, we will remain responsible for ensuring that each of our clinical trials is conducted in accordance with the general investigational plan, study protocols for the trial, statistical analysis plan and other study-specific documents (for example, monitoring and blinding plans). Moreover, the FDA requires us to comply with standards, commonly referred to as Good Clinical Practice (GCP), International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use, or ICH, guidelines, and regulations regarding the informed consent process, safety reporting requirements, data collection guidelines, and other regulations for conducting, recording and reporting the results of clinical trials to assure that data and reported results are credible and accurate and that the rights, integrity and confidentiality of trial participants are protected. The EMA also requires us to comply with similar standards. Regulatory authorities enforce these GCP requirements through periodic inspections of trial sponsors, principal investigators and trial sites. If we or any of our CROs fail to comply with applicable GCP requirements, the clinical data generated in our clinical trials may be deemed unreliable and the FDA, EMA or comparable foreign regulatory authorities may require us to perform additional clinical trials before approving our marketing applications. We cannot assure that upon inspection by a given regulatory authority, such regulatory authority will determine that any of our clinical trials comply with GCP and other applicable regulations. In addition, our clinical trials must be conducted with product produced under applicable current Good Manufacturing Practices (cGMP) and current Good Tissue Practices (cGTP) regulations. Our failure to comply with these regulations may require us to conduct new clinical trials, which would delay the marketing approval process. We also are required to register certain ongoing clinical trials and post the results of certain completed clinical trials on a government-sponsored database, ClinicalTrials.gov, within certain timeframes. Failure to do so can result in fines, adverse publicity and civil and criminal sanctions.

If we experience delays or quality issues in the conduct, completion or termination of any clinical trialstudy of our product candidates, the approval and commercial prospects of such product candidate will be harmed, and our ability to generate product revenues from such product candidate will be delayed. In addition, any delays in completing our clinical trialsstudies will increase our costs, slow down our product candidate development and approval process and jeopardize our ability to commence product sales and generate revenues. Any delays in completing our clinical trialsstudies for our product candidates may also decrease the period of commercial exclusivity. In addition, many of the factors that could cause a delay in the commencement or completion of clinical trialsstudies may also ultimately lead to the denial of regulatory approval of our product candidates.

Our product and product candidates, the methods used to deliver them or their dosage levels may cause undesirable side effects or have other properties that could delay or prevent their regulatory approval, limit the commercial profile of an approved label or result in significant negative consequences following any regulatory approval.

Undesirable side effects caused by our product and product candidates, their delivery methods or dosage levels could cause us or regulatory authorities to interrupt, delay or halt clinical trialsstudies and could result in a more restrictive label or the delay or denial of regulatory approval by the FDA or other comparable foreign regulatory authority. For example, hypoxia has been observed in some patients receiving ATA230 for the treatment of their CMV pneumonitis. As a result of safety or toxicity issues that we or our partners may experience in our clinical trials,studies, we or our partners may not receive approval to market any product candidates, which could prevent us from ever generating product or royalty revenues for such product candidates or achieving profitability. Results of our trialsstudies could reveal an unacceptably high severity and incidence of side effects.effects, or risks that outweigh the benefits of our product and product candidates. In such an event, our trialsstudies could be suspended or terminated, and the FDA or comparable foreign regulatory authorities could order us to cease further development of or deny approval of our product candidates for any or all targeted

indications. The drug-related side effects could affect patient recruitment or the ability of enrolled subjects to complete the trialstudy or result in potential product liability claims. Any of these occurrences may have a material adverse effect on our business, results of operations, financial condition, cash flows and future prospects.

Additionally, if any of our product candidates receives regulatory approval, and we or others later identify undesirable side effects caused by such product, a number of potentially significant negative consequences could result, including that:

Any of these events could diminish the usage or otherwise limit the commercial success of our product and product candidates and prevent us from achieving or maintaining market acceptance of the particularaffected product candidate, if approved.approved by applicable regulatory authorities.

The market opportunities for our product and product candidates may be limited to those patients who are ineligible for or have failed prior treatments and may be small.

The FDA often approves new cancer therapies initially only for use in patients with relapsed or refractory metastatic disease. We expect to seek initial approval of tab-cel and our other oncology product candidates in this setting. Subsequently, for those products that prove to be sufficiently beneficial, if any, we may seek approval for earlier lines of treatment and potentially as a first line therapy, but there is no guarantee that our product and product candidates, even if approved, would be approved for earlier lines of therapy, and, prior to any such approvals, we will have to conduct additional clinical trials.

Our projections of both the number of people who have the diseases we are targeting, as well as the subset of people with these diseases in a position to receive second or later lines of therapy, and who have the potential to benefit from treatment with our product and product candidates, are based on our current beliefs and estimates. These estimates have been derived from a variety of sources, including scientific literature, surveys of clinicians, patient foundations, or our own market research, and may prove to be incorrect. Further, new studies, product approvals, changes to the standard of care and diagnosis rates or scientific understanding of disease burden may change the estimated incidence or prevalence of these diseases, and the number of patients who could benefit from our products may turn out to be lower than expected. Additionally, the potentially addressable patient population for our product candidates may be limited or may not be amenable to treatment with our product candidates. For instance, we expect our product, tab-cel, to initially target a patient population that suffers from aggressive EBV+PTLD and has failed rituximab or rituximab plus chemotherapy. Our commercial partners may have different estimates of the market opportunities for our product or product candidates. At the outset of the COVID-19 pandemic, we initially observed a temporary slow-down in stem cell and solid organ transplant volumes. These reductions were transient, but if a reduction in such volumes resumes or if there are other disruptive factors that reduce PTLD incidence, such as changes in immunosuppression regimens or treatment of re-activated viremia, it could result in lower PTLD incidence and thus reduce the demand for tab-cel. Even if our product and product candidates obtain significant market share, because the potential target populations are small, we may never achieve profitability without obtaining regulatory approval for additional indications.

We may not be able to obtain or maintain orphan drug exclusivity for our product candidates.

Regulatory authorities in some jurisdictions, including the United StatesU.S., EU and Europe,the UK, may designate drugs for relatively small patient populations as orphan drugs. Under the Orphan Drug Act, the FDA may designate a product as an orphan drug if it is a drug intended to treat a rare disease or condition, which is generally defined as a patient population of fewer than 200,000 individuals annually in the United States. BothU.S. The FDA, the FDAEMA, and the EMAMHRA have granted us orphan statusdrug designation for tabelecleuceltab-cel for EBV+ PTLD after HCT or SOT. EMA has granted us orphan status for ATA230 for CMV infection in patients with impaired cell-mediated immunity and FDA has granted us orphan status for the ATA230 for the treatment of CMV viremia and disease in immunocompromised patients.PTLD.

Generally, if a product with an orphan drug designation subsequently receives the first regulatory approval for the indication for which it has such designation, the product is entitled to a period of marketing exclusivity, which precludes the FDA, the EMA, orand the FDAMHRA from approving another marketing application for the same drugbiologic for the same indication for that time period. The applicable period is seven years in the United StatesU.S. and ten years in Europe.the EU and the UK. The EuropeanEU and UK exclusivity periodperiods can be reduced to six years if a drug no longer meets the criteria for orphan drug designation or if the drug is sufficiently profitable so that market exclusivity is no longer justified. These periods may be reduced in the EU based on a new applicable legal framework, currently under review by the European Parliament and Council. Orphan drug exclusivity may be lost if the FDA, EMA or EMAMHRA determines that the request for designation was materially defective or if the manufacturer is unable to assure sufficient quantity of the drug to meet the needs of patients with the rare disease or condition. In the U.S., the FDA may still approve a later marketing application blocked by an ongoing period of orphan drug exclusivity in limited circumstances such as a showing of clinical superiority to the product with orphan drug exclusivity or if the FDA finds that the holder of the orphan drug exclusivity has not shown that it can assure the availability of sufficient quantities of the orphan drug to meet the needs of patients with the disease or condition for which the product was approved. As a result, even if one of our product candidates receives orphan exclusivity, the FDA can still approve or license other drugs or biological products that have a different active ingredient for use in treating the same indication or disease.

In addition, Congress is considering updates to the orphan drug provisions of the FDCA in response to a 2021 11th Circuit decision, Catalyst Pharms., Inc. v. Becerra, 14 F.4th 1299 (11th Cir. 2021), in which the court disagreed with the FDA’s longstanding position that the orphan drug exclusivity only applies to the approved use or indication within an eligible disease, and not to all uses or indications within the entire disease or condition. In particular, the circuit court held that that the orphan-drug exclusivity for the drug developed by Catalyst Pharmaceuticals, Inc. (Catalyst) blocked the FDA’s approval of another drug for all uses or indications within the same orphan-designated disease, Lambert-Eaton myasthenic syndrome (LEMS), even though Catalyst’s drug was approved at that time only for use in the treatment of LEMS in adults. Accordingly, the court ordered the FDA to set aside the approval of a drug indicated for LEMS in children. This decision created uncertainty in the application of the orphan drug exclusivity. Any changes to the orphan drug provisions could change our opportunities for, or likelihood of success in obtaining, orphan drug exclusivity and could materially adversely affect our business, financial condition, results of operations, cash flows and prospect.

Even if we obtain orphan drug exclusivity for a product, that exclusivity may not be maintained or effectively protect the product from competition because different drugs can be approved for the same condition. Even after an orphan drug is approved,

BTD by the FDA and PRIME designation by the EMA may not lead to a faster development or regulatory review or approval process and it does not increase the likelihood that our product candidates will receive marketing approval.

Although we have obtained BTD for tab-cel in the U.S. for treatment of patients with EBV+ PTLD who have failed rituximab, these designations may not lead to faster development or regulatory review and does not increase our likelihood of success. A breakthrough therapy is defined as a drug or biologic that is intended, alone or in combination with one or more other drugs or biologics, to treat a serious or life-threatening disease or condition and preliminary clinical evidence indicates that the drug, or biologic in our case, may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. For product candidates that have been designated as breakthrough therapies, interaction and communication between the FDA and the sponsor of the study can subsequently approvehelp to identify the most efficient path for clinical development while minimizing the number of patients placed in ineffective control regimens. Biologics designated as breakthrough therapies by the FDA may also be eligible for other expedited review programs, such as priority review. Based on our BTD, we may pursue a new drugrolling submission strategy for our BLA for tab-cel for EBV+ PTLD in the U.S. While a rolling review process may provide the opportunity for ongoing communications with and feedback from the FDA, it may not result in a faster timeline to marketing approval and has no bearing on whether or not tab-cel is ultimately approved. The FDA may raise issues and pose questions to us that may delay the initiation and completion of our BLA submission, acceptance of the complete BLA for filing, and approval of the BLA. We may not be able to provide a satisfactory or a timely response to FDA questions or we may not be able to gather the required data to prepare our BLA submissions as we plan. If we are unable to address all questions or concerns that the FDA may raise or if we do not have timely access to the data required for the same conditionpreparation of the BLA, we may not be able to initiate and complete our BLA in a timely manner and ultimately receive FDA approval. In addition, even if we submit our BLA under the rolling review process, the FDA concludesmay decide not to review portions of our BLA under the rolling review process until the submission is deemed to be complete.

PRIME designation supports the development and accelerated review by the EMA of new therapies to treat patients with unmet medical need. Despite this designation and the associated opportunity for accelerated assessment, the EMA may decide that additional time is needed for the MAA review and convert the MAA to a standard review timeline. For example, the EMA converted the tab-cel MAA review timeline from accelerated to standard.

Designation as a breakthrough therapy is at the discretion of the FDA, and access to PRIME is at the discretion of the EMA. Receipt of a BTD or PRIME designation for a product candidate may not result in a faster development process, review or approval compared to drugs considered for approval under non-expedited FDA or EMA review procedures and does not assure ultimate approval by either the FDA or EMA. In addition, the FDA or EMA, respectively, may later decide that the laterproduct no longer meets the conditions for qualification and rescind the BTD or PRIME designation or decide that the time period for FDA or EMA, respectively, review or approval will not be shortened. For example, in June 2022, FDA published a draft guidance document outlining considerations for the FDA in rescinding BTD for products that no longer meet the requirements for that designation.

A Fast Track designation by the FDA, even if granted for other current or future product candidates, may not lead to a faster development or regulatory review, licensure process and does not increase the likelihood that our product candidates will receive marketing licensure.

We may seek fast track designation for one or more of our future product candidates. If a drug or biological product is clinically superiorintended for the treatment of a serious or life-threatening disease or condition and it demonstrates the potential to address unmet medical needs for such a disease or condition, the drug sponsor may apply for FDA fast track designation for a particular indication. We may seek fast track designation for our product candidates, but there is no assurance that the FDA will grant this designation to any of our proposed product candidates. Marketing applications submitted by sponsors of products in fast track development may qualify for priority review under the policies and procedures offered by the FDA, but the fast track designation does not assure any such qualification or ultimate marketing licensure by the FDA. The FDA has broad discretion whether or not to grant fast track designation, so even if we believe a particular product candidate is eligible for this designation, there can be no assurance that the FDA would decide to grant it. Even if we do receive fast track designation, we may not experience a faster development process, review or licensure compared to conventional FDA procedures or pathways and receiving a fast track designation does not provide assurance of ultimate FDA licensure. In addition, the FDA may withdraw fast track designation at any time, including if it believes that the designation is shown to be safer, more effective or makes a major contribution to patient care.no longer supported by data from our clinical development program.

Failure to obtain regulatory or payor approval in international jurisdictions would prevent our product candidates from being marketed abroad.

In addition to regulations in the United States,U.S., to market and sell our products in the European Union,EU, the UK, many Asian countries and other jurisdictions, we, or our current or future commercialization partners, must obtain separate regulatory approvals and comply with numerous and varying regulatory requirements.requirements, both from a clinical and manufacturing perspective. The approval procedure varies among countries and can involve additional testing. The time required to obtain approval may differ substantially from that required to obtain FDA approval. The regulatory approval process outside the United StatesU.S. generally includes all of the risks associated with obtaining FDA approval.approval and may include additional risks. Clinical trialsstudies accepted in one country may not be accepted by regulatory authorities in other countries. In addition, many countries outside the United StatesU.S. require that a product be approved for reimbursement before it can be approved for sale in that country. A product candidate that has been approved for sale in a particular country may not receive reimbursement approval in that country. We or our partners may not be able to obtain approvals from regulatory authorities or payor authorities outside the United StatesU.S. on a timely basis, if at all. Approval by the FDAa regulatory agency or payor does not ensure approval by any other regulatory or payor authorities in other countries or jurisdictions, and approval by one regulatory authority outside the United States does not ensure approval by regulatory authorities in other countries or jurisdictions or by the FDA.jurisdictions. We may not be able to file for regulatory approvals and may not receive necessary approvals to commercialize our products in any market. If we or our partners are unable to obtain approval of any of our product candidates by regulatory or payor authorities in the European Union,US, EU, the UK, Asia or elsewhere, the commercial prospects of that product candidate may be significantly diminished, our business prospectsdiminished.

The proposed revision of the European legislation on pharmaceuticals could declinelead to uncertainties over the regulatory framework that will be applicable to medicinal products in the EU, including orphan medicinal products.

In April 2023, the EC published proposals to revise the existing European legislation on medicinal products (EU Pharma Law Review). The revisions consist of two proposals, a new directive and thisa new regulation (EU Pharma Law Proposal) that would amend and/or repeal and replace the relevant legislation concerning medicinal products for human use, including legislation concerning orphan medicinal products and medicinal products for pediatric use. The EU pharma Law Review could materially adversely affect our business, resultshave a significant impact on the designation of operations and financial condition.incentives offered to orphan medicinal products in the EU. If adopted in current form, the EU Pharma Law Proposal would introduce the possibility for the Commission, by way of delegated acts, to derogate from the current prevalence criterion, and introduce specific criteria for certain conditions, due to the characteristics of such conditions or other scientific reasons. The EU Pharma Law Proposal also proposes changes to the current orphan market exclusivity (OME) approach. If adopted in the

current form, the EU Pharma Law Proposal would in most cases reduce the duration of the OME and replace the current system of separate OME periods for each new indication with a system with a single OME period for each active substance.

Even if our product candidates receive regulatory approval, they may still face future development and regulatory difficulties.

Even if we, or our partners obtain regulatory approval for a product candidate, it would be subject to ongoing requirements by the FDA and comparable foreign regulatory authorities governing the manufacture, quality control, further development, labeling, packaging, storage, distribution, adverse event reporting, safety surveillance, import, export, advertising, promotion, recordkeeping and reporting of safety and other post-marketing information. These requirements include submissions of safety and other post-marketing information and reports, registration, as well as continued compliance by us and/or our contract manufacturing organizations, or CMOs and CROs for any post-approval clinical trialsstudies that we conduct. They also include any post-approval requirements or commitments imposed by FDA or comparable foreign regulatory authorities as a condition of approval, or any risk evaluation or mitigation strategies (REMS), if applicable. The safety profile of any product will continue to be closely monitored by the FDA and comparable foreign regulatory authorities after approval. If the FDA or comparable foreign regulatory authorities become aware of new safety information after approval of any of our product candidates, they may require labeling changes or establishment of a risk evaluation and mitigation strategy, impose significant restrictions on a product’s indicated uses or marketing or impose ongoing requirements for potentially costly post-approval studies or post-market surveillance.

In addition, manufacturers of drug products and their facilities are subject to initial and continual review and periodic inspections by the FDA and other regulatory authorities for compliance with current good manufacturing practices, or cGMP, current Good Clinical Practices, or GCP, current good tissue practices, or cGTP and other regulations. If we or a regulatory agency discover previously unknown problems with a product, such as adverse events of unanticipated severity or frequency, or problems with the facility where the product is manufactured, a regulatory agency may impose restrictions on that product, the manufacturing facility or us, including requiring recall or withdrawal of the product from the market or suspension of manufacturing. If we, our products, product candidates, or the manufacturing facilities for our products or product candidates fail to comply with applicable regulatory requirements, a regulatory agency may:

The occurrence of any event or penalty described above may also generate negative publicity or inhibit our ability to successfully commercialize our products and generate revenues.products.

Advertising and promotion of any product candidate that obtains approval in the United StatesU.S. will be heavily scrutinized by the FDA, the Department of Justice or the DOJ,(DOJ), the Office of Inspector General of the Department of Health and Human Services or HHS,(HHS), state attorneys general, members of the U.S. Congress and the public. Additionally, advertising and promotion of any product candidate that obtains approval outside of the United StatesU.S. will be heavily scrutinized by comparable foreign entities and stakeholders. For example, a company may not promote “off-label” uses for its drug products. An off-label use is the use of a product for an indication that is not described in the product’s FDA-approved label in the U.S. or for uses in other jurisdictions that differ from those approved by the applicable regulatory authorities.agencies. Physicians, on the other hand, may prescribe products for off-label uses. Although the FDA and other regulatory agencies do not regulate a physician’s choice of drug treatment made in the physician’s independent medical judgment, they do restrict promotional communications from companies or their sales force with respect to off-label uses of products for which marketing clearance has not been issued. However, companies may share truthful and not misleading information that is otherwise consistent with a product’s FDA approved labeling. Violations, including actual or alleged promotion of our products for unapproved or off-label uses, are subject to enforcement letters, inquiries and investigations, and civil and criminal sanctions by the FDA.FDA or

comparable foreign bodies. Any actual or alleged failure to comply with labeling and promotion requirements may have a negative impact on our business.result in fines, warning letters, mandates to corrective information to healthcare practitioners, injunctions, or civil or criminal penalties.

Regulations, guidelines and recommendations published by various government agencies and organizations may affect the use of our product candidates.

AlthoughChanges to regulations, recommendations or other guidelines advocating alternative therapies for the indications we treat could result in decreased use of our products. For example, although treatment with EBV specific T-cellsEBV-specific T cells is recognized as a recommended treatment for persistent or progressive EBV+ PTLD as set forth in the 2017 National Comprehensive Cancer Network Guidelines, future guidelines from governmental agencies, professional societies, practice management groups, private health/science foundations and other organizations involved in various diseases may relatecould lead to such matters asdecreased ability to develop our product usage, dosage, and route of administration and use of relatedcandidates, or competing therapies. Changes to these recommendations or other guidelines advocating alternative therapies could result in decreased use of our product candidates, which may adversely affect our results of operations.products once approved by applicable regulatory authorities.

We may not successfully identify, acquire, develop or commercialize new potential product candidates.

Part of our business strategy is to expand our product candidate pipeline by identifying and validating new product candidates, which we may develop ourselves, in-license or otherwise acquire from others. In addition, in the event that our existing product candidates do not receive regulatory approval or are not successfully commercialized, then the success of our business will depend on our ability to expand our product pipeline through internal development, in-licensing or other acquisitions. We may be unable to identify relevant product candidates. If we do identify such product candidates, we may be unable to reach acceptable terms with any third party from which we desire to in-license or acquire them.

We may not realize the benefits of strategic alliances that Any product candidates we may form in the future.

We may form strategic alliances, create joint venturesidentify, acquire, in-license, develop, or collaborations or enter into licensing arrangements with third parties that we believe will complement or augment our existing business. These relationships, or those like them, may require us to incur nonrecurring and other charges, increase our near- and long-term expenditures, issue securities that dilute our existing stockholders or disrupt our management and business. In addition, we face significant competition in seeking appropriate strategic alliances and the negotiation process is time-consuming and complex. Moreover, wemanufacture may not be successful in our efforts to establish a strategic alliancesafe or other alternative arrangementseffective for any future product candidatestheir targeted diseases, and programs because our research and development pipeline may be insufficient, our product candidates and programs may be deemed to be at too early a stage of development for collaborative effort and third parties may not view our product candidates and programs as having the requisite potential to demonstrate safety and efficacy. If we license productsreceive marketing authorization in a timely manner, or acquire businesses, we may not be able to realize the benefit of such transactions if we are unable to successfully integrate them with our existing operations and company culture. We cannot be certain that, following a strategic transaction or license, we will achieve the revenues or specific net income that justifies such transaction. Any delays in entering into new strategic alliances agreements related to our product candidates could also delay the development and commercialization of our product candidates and reduce their competitiveness even if they reach the market.at all.

Risks Related to Manufacturing

We are subject to a multitude of manufacturing risks, any of which could substantially increase our costs and limit supply of our product and product candidates.

ConcurrentConcurrently with the licensein-license of our existing product and product candidates, we acquired manufacturing process know-how and, certainin some cases, inventory of process intermediates as well as certain supplies intended forand clinical use,materials from MSK and QIMR Berghofer. To facilitate the manufacture of additional drug product for our Phase 3 clinical trials using the MSKpartners. Transferring manufacturing processes, testing and process know-how, we undertook the process of transferring this know-how to our CMO. Transferring manufacturing testing and processes andassociated know-how is complex and involves review and incorporation of both documented and undocumented processes that may have evolved over time. In addition, transferring production to different facilities may require utilization of new or different processes and/or equipment to meet the specific requirements of a given facility. WeEach stage is retroactively and concurrently verified to be compliant with appropriate regulations. As a result, there is a risk that all relevant know-how was not adequately transferred to us from our CMOs willpartners or that previous execution was not compliant with applicable regulations.

In addition, we need to conduct significant development and scale-up work to transfer these processes and manufacture each of our product and product candidates for various studies, trialsclinical studies and commercial launch readiness. We cannot be certain that all relevant know-how has been adequately incorporated intoTo the extent we elect to transfer manufacturing process until the completionwithin our network of studies (and the related evaluations) intendedthird party CMOs, we are required to demonstrate that the comparability of material previously produced by MSK with that generated by our CMO.product manufactured in the new or “receiving” facility is comparable to the product manufactured in the original or “sending” facility. The inability to manufacturedemonstrate to each of the applicable regulatory authorities that comparable drug product by us or our CMOwas manufactured could delay the continued development of our product candidates.  Although we believe we have manufactured material that is comparable to that previously produced by MSK, the FDA, EMA, and other comparable regulatory authorities may not agree.candidates or availability of additional commercial product supplies.

The processes by which some of our product and product candidates are manufactured were initially developed by MSK or QIMR Berghoferour partners for clinical purposes. We and our CMO intend to evolve these existingthe processes for moredeveloped by our partners and the processes developed by us to support advanced clinical trials or commercialization.studies and commercialization requirements. We similarly intend to evolve the processes originating at Atara to support advanced clinical studies and commercialization requirements. Developing commercially viable manufacturing processes is a difficult and uncertain task, and there are risks associated with scaling to the level required for advanced clinical trialsstudies or commercialization, including cost overruns, potential problems with process scale-up, process reproducibility, comparability issues, stability, safety, purity and potency issues, regulatory agency review and endorsement processes, consistency and timely availability of reagents or raw materials. The manufacturing facilities in which our product and product candidates will be made could be adversely affected by pandemics, earthquakes and other natural or man-made disasters, equipment failures, labor shortages, power failures, and numerous other factors.

Additionally, In addition, there have been, and there may continue to be, transient interruptions in the processsupply of raw materials and consumables used in the development and manufacturing biologicsof our preclinical and cellularclinical cell therapies is complex, highly regulatedrelated to raw material shortages due to the COVID-19 pandemic or other global pressures, including leukapheresis collections, which supply starting materials used in our product and subjectproduct candidates, and raw materials and consumables specialized for cell therapy manufacturing. If we are unable to several risks, including but not limited to:obtain such raw materials or other necessary raw materials in a timely manner, our business operations and manufacturing capabilities could be adversely affected.

The process of manufacturing cellular therapies is extremely susceptible to product loss due to contamination, equipment failure or improper installation or operation of equipment, or vendor or operator error. Even minor deviations from normal manufacturing and distribution processes for any of our product and product candidates could result in reduced production yields, impact to key product defects,quality attributes, and other supply disruptions. Product defects can also occur unexpectedly. If microbial, viral or other contaminations arecontamination is discovered in reagents or in our product and product candidates or in the manufacturing facilities in which our product and product candidates are made, suchthese manufacturing facilities may need to be closed for an extended period of time to allow us to investigate and remedy the contamination;contamination. For example, we were informed by a CMO of mold contamination in certain manufacturing suites related to the manufacture of finished Ebvallo and