In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “contemplate,” “believe,” “estimate,” “predict,” “potential”, or “continue” or the negative of these terms or other similar expressions. The forward-looking statements in this Annual Report are only predictions. We have based these forward-looking statements largely on our current expectations and projections about future events and financial trends that we believe may affect our business, financial condition and results of operations. These forward-looking statements speak only as of the date of this Annual Report and are subject to a number of important factors that could cause actual results to differ materially from those in the forward-looking statements, including the factors described under the sections in this Annual Report titled “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” as well as the following:

Moreover, we operate in an evolving environment. New risk factorsrisks and uncertainties may emerge from time to time, and it is not possible for management to predict all risk factors and uncertainties.

You should read this Annual Report and the documents that we reference in this Annual Report completely and with the understanding that our actual future results may be materially different from what we expect. We qualify all of our forward-looking statements by these cautionary statements. Except as required by applicable law, we do not plan to publicly update or revise any forward-looking statements contained herein, whether as a result of any new information, future events, changed circumstances or otherwise.

We are a clinical-stage biopharmaceutical company using our ImmTOR™company. Our ImmTOR® platform encapsulates rapamycin, also known as sirolimus, an FDA approved immunomodulator, in biodegradable nanoparticles ImmTOR is designed to induce antigen-specific immune tolerance.

By combining ImmTOR with antigens of interest, our precision immune tolerance platform has the potential to novel biologic therapies that would otherwise be limited by immunogenicity withrestore self-tolerance to auto-antigens in autoimmune diseases, amplify the goalefficacy of effectivelybiologics (including gene therapies) and safely treating rare and serious diseases. Many such diseases are treated with biologic therapies that are foreign tomitigate the patient’s immune system and therefore elicit an undesired immune response. Of particular concern areformation of anti-drug antibodies, or ADAs, which are often produced by the immune system in response to biologic therapy and can adversely affect the efficacy and safety of treatment. Our proprietary tolerogenic ImmTOR platform encapsulates an immunomodulator in biodegradable nanoparticles and is designed to mitigate the formation of ADAs by inducing antigen-specific immune tolerance toagainst biologic drugs. ADAs can start developing in the body with the first dose of a biologic therapy and can render subsequent doses ineffective or unsafe, potentially depriving patients of life-saving therapeutic options and limiting the likelihood of success for many otherwise promising novel biologic drugs and technologies.

We believe ImmTOR hasand ImmTOR-IL have the potential to enhance both the efficacy without compromising theand safety of existing approved biologic drugs,therapies (including gene therapies), improve product candidates under development, and enable novel therapeutic modalities such as re-administration of systemic gene therapy. We intendin autoimmune disease. In clinical trials, ImmTOR has been observed to build a product pipeline by combining our ImmTOR platform with a range of biologics. Additionally, we plan to seek collaborations and license agreements to broaden our applications for our ImmTOR platform.

We have developed a portfolio of wholly owned and partnered candidates across gene therapies, biologic therapies and tolerogenic therapies for autoimmune diseases that leverage our ImmTOR platform. We plan to enter the clinic under this collaboration in 2020. For more information, see "Licenses and Collaborations - AskBio” below.

ImmTOR consists of ourbiodegradable nanoparticles encapsulating the immunomodulator rapamycin. Rapamycin is the active ingredient of Rapamune, an immunosuppressant that has been used extensively in humans and is currently FDA-approved as a prophylaxis of organ rejection in kidney transplant patients aged 13 or older. The rapamycin component of ImmTOR platform. In December 2016, we entered intois embedded in a license agreement, or the Spark License Agreement, with Spark Therapeutics, Inc.matrix of synthetic polymers called poly(D,L-lactide), or Spark, that provides Spark with exclusive worldwide rights to our ImmTOR platform to research, developPLA, and commercialize gene therapies for Factor VIII, an essential blood clotting protein relevant to the treatment of hemophilia A. For more information,

Our nanoparticles are designed to remain intact after injection into the body and accumulate selectivelypredominantly in lymphoid organs, which include lymph nodes, the spleen, and the spleen,liver, where the immune response isresponses are coordinated. The nanoparticles are designed to be processed by specialized immune cells, such as dendritic cells and other antigen-presenting cells, that initiate and regulate immune responses, where they deliver the immunomodulator in a coordinated and targeted manner. Depending on the type of immunomodulator encapsulated in the nanoparticles, our technology can be usedresponses. ImmTOR is intended to induce a tolerogenic response to mitigatephenotype in these antigen-presenting cells, which then process and present co-administered antigens in a manner that results in the formationinduction of ADAs against a biologic drug or to treat allergies and autoimmune diseases.

In the case of a biologic drug, which is depicted in Figure 2 below.

In our preclinical studies, we observed that ImmTOR combined with a Treg-selective IL-2 mutant protein, or IL-2 mutein, exhibited substantial synergistic activity in increasing the percentage and durability of total Treg expansion in the spleen. We believe that this combination has the potential to be a best-in-class therapy in diseases where expansion of total Treg may prove beneficial. The tables below show the synergistic expansion of total Treg we observed with treatment with ImmTOR and Antigen/Biologic Drug Presentationa Treg-selective IL-2 mutein. In the study, seven C57BL/6 mice per group were untreated, treated with ImmTOR alone, treated with IL-2 mutein alone or treated with a combination of ImmTOR and Related Immune Tolerance InductionIL-2 mutein. Expansion of CD4+, CD25+ and FoxP3+ T regulatory cells in the spleen was assessed at four, seven and 14 days after treatment.

We believe that the power of existing therapies

Immune homeostasis is a dynamic process balancing immune stimulatory and immune tolerizing signals. This balance is thought to be mediated in part by the ratio of antigen-specific Treg to antigen-specific effector T cells. The expansion of antigen-specific Tregs has the potential to better withstand potent immune stimulatory signals and provide better durability of immune tolerance. In a preclinical study, we evaluated the ability of ImmTOR and IL-2 mutein to mitigate the immunogenicity to a co-administered AAV vector. Mice were injected with a dose of 2.7E12 vg/kg AAV8 on Day 0 and 5.0E12 vg/kg on Day 56 with or without IL-2 mutein and/or ImmTOR on the same days. Mice treated with AAV alone showed a robust antibody response dependsto the AAV capsid, as we had expected. Co-treatment with IL-2 mutein on both product-specific factors, such as propensityDays 0 and 56 showed a modest attenuation of the antibody response. Co-treatment with ImmTOR on Days 0 and 56 showed a dose-responsive effect on the antibody response, with a therapeutic dose of 200 µg ImmTOR providing inhibition of antibodies against AAV through at least Day 75, or 19 days after the second dose. At Day 91, some animals showed breakthrough of the antibody response. ImmTOR doses of 50 and 100 µg alone were sub-optimal. However, when ImmTOR was combined with IL-2 mutein, we observed inhibition of antibody formation through Day 117, 61 days after the second dose and the last time point measured. Importantly full inhibition of anti-AAV immunoglobulin G, or IgG, antibodies was observed even when IL-2 mutein was combined with 50 and 100 µg doses of ImmTOR. We believe these results suggest that the addition of a Treg-selective IL-2 to form aggregates,ImmTOR has the routepotential to increase the durability of administrationtolerance allow for dose-sparing of ImmTOR and mechanismthus, potentially enabling chronic dosing of action, as well as patient-specific factors, such as genetics, underlying disease and medications. For instance, many enzyme and protein replacement therapies usedImmTOR-IL in the treatment of rareautoimmune disease. The following graphs illustrate the combination of ImmTOR and serious diseases have a particularly high rate of immunogenicity because patients are genetically deficient in the target protein and, as a result, the therapeutic protein can be recognized as foreign by the patient’s immune system.

In preclinical studies and in our biodegradable nanoparticle that encapsulates rapamycin, also referred to as sirolimus. Rapamycin is the active ingredient of Rapamune, an immunosuppressant which has extensive prior use in humansPhase 1b and is currently FDA-approved as a prophylaxis of organ rejection in kidney transplant patients aged 13 or older. PLA is part of the broader poly(lactic-co-glycolic acid), or PLGA, family of biodegradable polymers that have more than 30 years of commercial use and are formulation components in a number of approved products. Polyethylene glycol, or PEG, has been widely studied inPhase 2 clinical trials, and is also a formulation component in many approved biologic products. In our preclinical studies,we observed that ImmTOR, when co-administered at the initiation of treatment with a biologic drugpegadricase, SEL-212 substantially reduced the formation of associated ADAsADAs. We believe that SEL-212 serves as proof of concept for the ImmTOR platform in ameliorating the unwanted immune response to an immunogenic biologic. SEL-212 is in two pivotal Phase 3 studies versus placebo, which we refer to as DISSOLVE I and induced antigen-specific immune toleranceDISSOLVE II, with top-line data expected in the fourth quarter of 2022. SEL-212 has been licensed (except as to Greater China) to Sobi, pursuant to our license and development agreement dated June 11, 2020, with Sobi, or the Sobi License.

Enrollment into the DISSOLVE II trial is ongoing and the study is being conducted in the United States and four countries across eastern Europe. As a result of the ongoing and rapidly evolving geopolitical situation in Ukraine and Russia, we have proactively undertaken mitigation steps to prioritize the safety of our patients and investigators, as well as address any potential disruptions. While we have temporarily closed screening and randomization at sites in both Russia and Ukraine, we have added 11 sites in the United States to further enrollment in DISSOLVE II. Out of these additional enrollment sites, nine have been activated and two are pending initiation, with activation expected imminently. Subject to ongoing geopolitical developments, we believe we remain on track to report data in the fourth quarter of 2022, and we will continue to work closely with our partner Sobi, clinical trial providers and regulatory authorities to evaluate any potential delays or adjustments to the biologic drug.timeline of the trial as a result of the circumstances.

For chronic refractory gout, we are executingGout is a clinical development program that seeks to evaluate SEL-212’s ability to durably reduce SUApainful and potentially disabling form of arthritis associated with elevation of sUA levels below 6.0 mg/dL. The saturation pointcaused by an overproduction of uric acid and/or an inability of the maximum level at whichkidneys to excrete adequate amounts of uric acid will remain soluble in plasma, is 6.8 mg/dL. Whenfrom the body. High concentrations of sUA lead to formation of uric acid rises above 6.8 mg/dL, uric acid microcrystals begin to form and settlecrystals in joints and tissues, causing pain, inflammation and joint damage, and increase the risk for other tissues, creating an inflammatory response that is diagnosed as gout. This inflammatory response is the source of highly debilitating gout flares experienced by patients. When serum uric acid levels drop below the level of 6.0 mg/dL, microcrystals will beginconditions, including cardiovascular, cardiometabolic, joint and kidney disease.

Patients who are unable to dissolve and, over time, gout symptoms will resolve. Therefore, a serum uric acid level of less than 6.0 mg/dL is defined as the target for uric acid-lowering treatments by organizations such as the American College of Rheumatology and the European League Against Rheumatism. The FDA and EMA have also considered the maintenance of serum uric acidreduce their sUA levels below 6.0 mg/dL with oral drugs are defined as having refractory gout. Chronic refractory gout constitutes a subset of gout patients exhibiting chronic high sUA levels and painful and damaging uric acid deposits. We estimate that there are approximately 160,000 chronic refractory gout patients in the U.S.

We believe SEL-212 may potentially address several key unmet needs in the treatment of chronic refractory gout: the durable control of sUA levels, the elimination of painful and damaging uric acid deposits, reduction in incidence and severity of flares, based on our preclinical studies, clinical trials, and market research. SEL-212 is designed to be an acceptable primary endpoint inaddress these unmet medical needs while improving the dosing regimen to a once-monthly treatment.

We conducted Phase 1a, Phase 1b, and Phase 2 clinical trials for urate lowering therapies. Available oral gout therapies are designed to prevent the formation of uric acid microcrystals but are not effective in rapidly removing existing crystalized deposits. In severe gout patients who have significant deposits of uric acid crystals, known as tophi, it is of clinical benefit to significantly reduce serum uric acid levels (i.e. below 0.1 mg/dL) for a period of time in order to rapidly dissolve the uric acid crystals.

In the patients during a 30-day period post-infusion. We commenced enrollment of the clinicalPhase 1a trial, in the second quarter of 2015 and completed the treatment portion of the trial in November 2015. We observed that pegadricase showed no serious adverse events, or SAEs, and was well tolerated at the five dose levels tested. Additionally, we observed that a single dose of pegadricase rapidly reduced and sustained average serum uric acidSUA levels below 6.0 mg/dL for each cohort for 14dose level, although SUA levels returned close to 30 days, depending on the dose level.baseline by day 30. Consistent with our preclinical studies in animals, pegadricase induced uricase-specific ADAs in all patients with varying levels in this Phase 1a trial. The following table depicts the observations from the single ascending dose trial of pegadricase in patients with hyperuricemia. In this trial, patients with SUA > 6 mg/dL at screening were assigned to one of five cohorts receiving a single IV infusion of pegadricase (0.1, 0.2, 0.4, 0.8 or 1.2 mg/kg). Each cohort consisted of five patients, except for cohort 5 (1.2 mg/kg) which enrolled two patients.

In the Phase 1a clinical trial, which received a single dose of 0.4 mg/kg of pegadricase. The serum uric acid levels were measured at baseline and days seven, 14, 21 and 30 and uricase-specific ADA levels at baseline and days seven, 14 and 30 following the single intravenous injection of pegadricase. We did not measure uricase-specific ADA levels at day 21 in the Phase 1a clinical trial. Patient number two in this cohort developed a relatively low level uricase-specific ADA titer of 40 and maintained uric acid levels below 0.5 mg/dL through the thirtieth day after dosing. By contrast, the remaining four patients in the cohort developed levels of uricase-specific ADAs greater than 1,000 titer and uric acid levels above 5 mg/dL by the thirtieth day after dosing. Based on the results from our Phase 1a1b clinical trial, we observed thatthe potential for increasing doses of ImmTOR to mitigate the formation of pegadricase atADAs and sustain the 0.4 mg/kg dose is capableanti-uricase enzyme activity through 30 days. The cohort of achieving and maintaining a reduction of serum uric acid below the target of 6.0 mg/dL for a 30-day period in the absence of inhibitory uricase-specific ADAs.

The Phase 2 trial included patients with symptomatic gout and elevated SUA levels in an open-label, multiple ascending-dose clinical trial of serum uric acidSEL-212 to demonstrate sustained reduction of less than 0.1 mg/dL through day 30.SUA and identify the best dose for Phase 3. Five monthly doses of SEL-212 patients receiving ImmTOR at 0.15 mg/kg co-administered with 0.4 mg/kg of pegadricase, showed all five patients maintaining levels of serum uric acid ofreduced SUA to less than 6.0 mg/dL through day 30. Finally, SEL-212in 21 of 32 patients, receiving ImmTOR at 0.3 mg/kg c- administered with 0.4 mg/kg ofor 66%. In distinct contrast, pegadricase showed all five patients maintaining levels of serum uric acid ofalone reduced SUA to less than 0.16.0 mg/dL through day 30. These results indicated that SEL-212 showed a dose-dependent reduction in serum uric acid levels.

We have generally observed that SEL‑212 and its components, ImmTOR and pegadricase, have beenwere generally well-tolerated in the Phase 1a, 1b, and 2 clinical trials. In the Phase 1a trial we observed no serious adverse events, or SAEs, and that pegadricase was well tolerated in this patient population. There were a total ofat the five dose levels tested. Of the six SAEs in the Phase 1b trial. Of the six SAEs,trial, three were determined to not to be related to study drug by investigators. Of the remaining three SAEs that were determined to possibly or likely be related to study drug, two were cases of stomatitis that occurred at the highest dose of ImmTOR tested (0.5 mg/kg), leading us to define 0.3 mg/kg as the maximum tolerated dose of ImmTOR in this patient population. The remaining SAE was a case of drug hypersensitivity that occurred at a dose of 0.1 mg/kg of ImmTOR in combination with 0.4 mg/kg of pegadricase. In all cases, the patient fully recovered from the SAE without residual effects.

In March 2019, we initiated a non-registrational Phase 2 head-to-head clinical trial of SEL-212, (COMPARE),which we refer to as COMPARE, in which SEL-212 is beingwas compared against the current FDA-approved therapy for chronic refractory gout, KRYSTEXXA,pegloticase, in multiple clinical sites in the United States.

In September 2020, we announced top-line results from the COMPARE trial. We completedobserved a numerically higher response rate to pegloticase on the primary endpoint during months three and six combined but did not meet the primary endpoint of statistical superiority. SEL-212 did generate a statistically significant higher response rate of SEL-212 during the third month of treatment, as well as a statistically significant greater overall reduction in mean SUA levels in SEL-212 versus pegloticase in months three and six combined. We observed a numerically higher response rate of SEL-212 during the sixth month of treatment. In patients with tophi at baseline, we observed substantially higher responder rates for SEL-212 compared to pegloticase on the primary endpoint, and a statistically significant reduction in mean SUA levels when compared to pegloticase.

We commenced enrollment of this studyDISSOLVE I in September 2020 and DISSOLVE II in December 20192020. In December 2021, we announced the completion of enrollment of the DISSOLVE I trial. DISSOLVE I has a six-month primary endpoint followed by a six-month safety extension. DISSOLVE II will have a six-month primary endpoint with no extension. The primary endpoint of the DISSOLVE program is the maintenance of sUA levels below 6 mg/dL at six months. We currently expect that topline data from the Phase 3 DISSOLVE clinical program is expected in the fourth quarter of 2022.

Enrollment into the DISSOLVE II trial is ongoing and expectthe study is being conducted in the United States and four countries across eastern Europe. As a result of the ongoing and rapidly evolving geopolitical situation in Ukraine and Russia, we have proactively undertaken mitigation steps to prioritize the safety of our patients and investigators, as well as address any potential disruptions. While we have temporarily closed screening and randomization at sites in both Russia and Ukraine, we have added 11 sites in the United States to further enrollment in DISSOLVE II. Out of these additional enrollment sites, nine have been activated and two are pending initiation, with activation expected imminently. Subject to ongoing geopolitical developments, we currently believe we remain on track to report top-line data in the fourth quarter of 2022, and we will continue to work closely with our partner Sobi, clinical trial providers and regulatory authorities to evaluate any potential delays or adjustments to the timeline of the trial as a result of the circumstances.

Our lead therapeutic gene therapy program, SEL-302, is intended to use ImmTOR to enhance the treatment of methylmalonic acidemia, or MMA, an inherited disorder in which the body is unable to process certain proteins and fats (lipids) properly. This program was previously being conducted under our collaboration with AskBio. In October and November 2020, we received rare pediatric disease designation and orphan drug designation, respectively, from the FDA for MMA-101, for the treatment of MMA due to methylmalonyl-CoA mutase, or MMUT gene mutations. See “⸺Licenses and Collaborations⸺AskBio” for more information. In April 2021, we were notified by AskBio that it intended to opt-out of development of the MMA indication. The feasibility study and license agreement with AskBio, or AskBio Collaboration Agreement, otherwise remains in effect. Manufacturing of a new lot has been completed and is currently undergoing final release testing. We filed an IND to conduct a Phase 1/2 clinical trial of SEL-302 in pediatric patients with methylmalonic acidemia in the third quarter of 2020. The two-armed, open label2021. On November 23, 2021, this trial has enrolled approximately 150 patients, randomized 1:1,was placed on clinical hold by the FDA, with one arm receiving KRYSTEXXA (as set forthquestions specifically relating to chemistry, manufacturing and controls, or CMC, of the AAV vector. On February 9, 2022, we submitted a written response to the FDA to answer its questions. On March 9, 2022, we received a letter from the FDA indicating the clinical hold was removed and the trial may proceed.

Our second proprietary gene therapy product candidate, SEL-313, is being developed to treat ornithine transcarbamylase, or OTC deficiency, and is currently in preclinical development. OTC deficiency is a rare genetic disorder that causes ammonia to accumulate in the prescribing information) and the other arm receiving six monthly doses of SEL-212. The primary endpointblood due to mutations in the studyOTC gene, which is the percentage of patients in each arm that maintain SUA control below 6.0 mg/dL,critical for at least 80%proper function of the time during months threeurea cycle. The most severe form of the disorder presents within the first few days of life. Severe symptoms include inability to control body temperature and six.breathing rate, seizures, coma, developmental delays and intellectual disability. Less severe forms of the disorder are characterized by delirium, erratic behavior, aversion to high protein foods, vomiting and seizures. The development of this program is currently paused.

OurWe have exclusively licensed Xork, an IgG-specific protease from Genovis, an enzyme technology company. We plan to develop Xork, either alone or in combination with our ImmTOR programsplatform, with the goal of enabling the dosing of transformative gene therapies in patients with pre-existing AAV immunity due to natural exposures to AAV viruses. Currently, significant proportions of the potential patient populations for immune tolerance in gene therapy

Because of this, the inductioncommercial potential of lasting antibodies against AAV, we believe many gene therapy companies have focused ontherapies may be significantly limited due to the single localized dose in diseasesineligibility of large segments of the eyetarget patient population. This is particularly important for gene therapies given the low incidence and central nervous systemsmall prevalent populations of rare monogenic diseases which many gene therapies target. Patients that are ineligible for which immunogenicity is perceivedgene therapy due to be lesspre-existing immunity may have few or no alternative therapies available to them.

Xork, as a pre-treatment in advance of an issue.AAV gene therapy, can potentially open a treatment window by cleaving the IgG antibodies and transiently reducing their concentration.

IgG proteases are bacterial proteins, which are themselves immunogenic. We believe that manyXork is differentiated from other IgG proteases since it is not derived from a human pathogen and thus, exhibits low cross-reactivity with human sera. Additionally, to further reduce any potential immunogenicity of the Xork enzyme, we plan to explore the combination of Xork and ImmTOR. The following images depict how Xork cleaves human IgG specifically and efficiently, but shows low cross reactivity to human sera compared to IdeS, an IgG protease derived from the common human pathogen Streptococcus pyogenes.

We believe that the combination of Xork and ImmTOR has the potential to address two of the major challenges to AAV gene therapy, applications may require or would benefit from multiple doses, especiallypre-existing immunity that limits eligibility and de novo immunogenicity that can adversely affect safety and durability and which prevents the ability to re-dose AAV. We plan to explore the application of Xork in combination with our wholly owned gene therapies, designedas well as explore partnering opportunities for the enzyme with other gene therapy companies.

We intend to apply our ImmTOR platform to treat autoimmune diseases. In preclinical studies, we have observed ImmTOR’s ability to induce antigen-specific T regulatory cells. We believe that ImmTOR, in combination with an autoantigen of interest, could create self-tolerance to auto-antigens and thus be a novel approach to the treatment of autoimmune diseases.

Additionally, in preclinical studies we have observed ImmTOR, in combination with IL-2 muteins, expanding T-regulatory cells beyond IL-2 alone and we intend to pursue a combination of ImmTOR and IL-2 (ImmTOR-IL) in diseases via intravenous administration. Somewhere general T cell expansion has shown a therapeutic benefit. Additionally, in our preclinical data we have observed a three-fold increase in antigen specific regulatory T cells when ImmTOR and IL-2 is combined with an antigen of these rare genetic deficienciesinterest. We intend to pursue and develop treatments for autoimmune diseases with well-defined antigens using either ImmTOR or ImmTOR-IL.

Cyrus Biotechnology, Inc., a collaboration partner, is engineering a proprietary IL-2 protein to combine with the ImmTOR platform to potentially mitigate unwanted immune responses by reducing the inherent immunogenicity of the protein while also promoting immune tolerance. The IL-2 pathway influences critical aspects of both immune stimulation and immune regulation, through the development and expansion of Treg cells. These Treg cells are best treated when patientsa specialized subpopulation of T cells involved in suppressing certain immune responses and maintaining the body’s self-tolerance. In preclinical studies investigating the effects of ImmTOR in combination with a Treg-selective IL-2 mutant protein, or IL-2 mutein, we have observed a substantial synergistic activity in increasing the percentage and durability of Treg expansion in the spleen.

Our lead autoimmune diseases indication is PBC, a T cell driven autoimmune disease that causes progressive destruction of the bile ducts. Patients with PBC are infantsin need of a highly targeted, liver-directed approach to treating the root cause of the disorder. We believe PBC has a well-defined target antigen, significant unmet medical need, and is well suited to the application of our ImmTOR immune tolerance platform, as preclinical data suggest that ImmTOR has the potential to enhance the tolerogenic environment in the liver and provide a hepatoprotective benefit.

We intend to both partner and strategically out-license ImmTOR, ImmTOR-IL and Xork for use with other products that are outside our focus to larger biopharmaceutical companies. We believe our ImmTOR platform may also be of interest to biopharmaceutical companies with novel biologic development concepts or small childrenproduct candidates in clinical development that have demonstrated initial efficacy but are experiencing issues with safety or sustained efficacy due to inhibitory ADAs. Additionally, we may strategically in-license products to combine with ImmTOR and develop novel therapeutic products independently. Our key partnerships are listed below.

On September 7, 2021, we entered into a Collaboration and License Agreement with Cyrus, or the Cyrus Agreement, pursuant to which Cyrus agreed to grant us an exclusive, worldwide license to certain intellectual property in order to prevent developmental defects. However, pediatric patientsform a protein engineering collaboration combining the ImmTOR platform with Cyrus’ engineered protein therapeutics. We expect that novel engineered protein therapeutic candidates from the partnership will be used to expand our proprietary pipeline and further bolster the ImmTOR platform. In return for the licensed intellectual property, we made an upfront payment and will pay certain discovery, development, and sales-based milestones which could potentially total up to approximately $1.5 billion across multiple programs.

Upon execution of the IGAN Agreement, we paid IGAN a one-time upfront payment of $0.5 million and we would owe additional payments to IGAN if we were to opt-in to an exclusive license agreement, as well as upon the achievement of certain development and sales milestones. During the Option Term, we may haveterminate the IGAN Agreement immediately for any reason upon written notice to IGAN. If we opt-in to an exclusive license agreement, we may terminate the IGAN Agreement upon 120 days’ written notice.

On October 1, 2021, we entered into a higher needstrategic licensing agreement with Takeda, or the Takeda Agreement. Under the Takeda Agreement, we granted Takeda an exclusive license to our ImmTOR technology initially for repeat dosing duetwo specified disease indications within the field of lysosomal storage disorders. Under the terms of the Takeda Agreement, we received an upfront payment and are entitled to higher cell turnoverreceive up to $1.124 billion in future additional payments over the course of the partnership that are contingent on the achievement of development or commercial milestones or Takeda’s election to continue its activities at specified development stages. We are also eligible for tiered royalties on future commercial sales of any licensed products.

Additionally, Sobi purchased an aggregate of 5,416,390 shares of our common stock at a purchase price of $4.6156 per share for aggregate gross proceeds of $25 million, which we refer to as the patient grows. Accordingly,Sobi Private Placement. The closing of the Sobi Private Placement occurred on July 31, 2020.

Under the Sobi License, we believewill have operational oversight of the Phase 3 DISSOLVE clinical program of SEL-212 (DISSOLVE I and DISSOLVE II) that commenced in September 2020, at Sobi’s expense.

In June 2020, we entered into a solution enabling repeat dosingresearch license and option agreement with Sarepta, or the Sarepta Agreement. Pursuant to the agreement, we granted Sarepta a license to research and evaluate ImmTOR in combination with Sarepta’s AAV gene therapy or gene editing technology, using viral or non-viral delivery, or the Sarepta Product, to treat Duchenne Muscular Dystrophy and certain Limb-Girdle Muscular Dystrophy subtypes, or the Sarepta Indications. Sarepta will have an option term of 24 months during which it can opt-in to obtain an exclusive license to further develop and commercialize the Sarepta Product to treat at least one Sarepta Indication, with a potential to extend the option term if Sarepta pays an additional fee to us. Sarepta made an upfront payment to us upon signing of the agreement, and we are eligible to receive additional payments under the option term. If Sarepta opts-in to an exclusive license agreement, we could receive option exercise payments per indication and we would significantly expandbe entitled to significant development and commercial milestone payments and tiered royalties ranging from the numbermid-to-high single digits based on net sales. In June 2021, we received a payment of diseases and patients that could be treated with gene therapies.

In August 2019, we entered into a feasibility study and license agreement with AskBio, or the AskBio Collaboration Agreement, pursuant to which we and AskBio will conduct proof of concept studies to potentially validate the use of our ImmTOR platform in conjunction with an AAV gene therapy to mitigate the formation of neutralizing anti-AAV capsid antibodies, which currently precludes redosing. One of theAgreement. The initial product candidatescandidate being developed under this collaboration is a gene therapy candidate for MMA which can cause severe developmental defects and premature death as a result of an accumulation of toxic metabolites. We previously conducted preclinical studies for this product candidate based on SEL-302 and will leverage that previous work within the collaboration.

In December 2019, we entered into the AskBio License Agreement. PursuantAgreement which provides AskBio with exclusive worldwide rights to the AskBio License Agreement, AskBio exercised its option to exclusively license our intellectual property rights covering ImmTOR platform to research, develop and commercialize certain AAV geneAAV-gene therapy products utilizing ImmTOR, and targeting the GAA gene, or derivatives thereof, to treat Pompe Disease, which we refer to as the Licensed Products.

We will supply AskBio with our ImmTOR platform and AskBio will be responsible for all preclinical, clinical and commercial manufacture and supply of Licensed Productsproducts licensed under the AskBio License Agreement (other than ImmTOR) and carry out all other activities related to the research, development, and commercialization of Licensed Productssuch products at its sole expense, including all regulatory activities related thereto.

In November 2008, we entered into a license agreement with the Massachusetts Institute of Technology, or MIT, which we refer to in its amended form as the MIT License. We amended the MIT License in January 2010, November 2012, August 2013, November 2016, December 2019 and December 2019.June 2020. Under the MIT License, we acquired an exclusive worldwide license, with the right to grant

Upon our entry into the MIT License, we paid MIT a non-refundable license issue fee, reimbursed certain of MIT’s costs and issued shares of our common stock to MIT and the other institutional patent owners which were subject to certain anti-dilution, registration and other protective rights. We are obligated to pay MIT creditable annual maintenance fees, low-single-digit running royalty on annual net sales, developmental milestones up to an aggregate of $1.5 million, a mid-single digit percentage of certain payments we receive from corporate partners and a specified percentage of certain income received from sublicensees after 2009 between 10% and 30%. We may terminate the MIT License at any time upon six monthsmonths’ written notice. MIT has the right to terminate the MIT License immediately upon written notice to us if we cease to carry on our business related to the MIT License, fail to maintain insurance as required under the MIT License, file for bankruptcy, fail to pay amounts due under the MIT License, challenge or assist others in bringing a challenge to MIT’s patents or fail to cure material breach within 60

MIT may terminate the MIT License if we fail to meet a diligence obligation, including the initiation of a Phase 3 clinical trial by a specified date in the fourth quarter of 2019. In December 2019,June 2020, we entered into the Fourtha Fifth Amendment to the MIT License, which we refer to asor the MIT Amendment.Amendment, which was effective as of May 15, 2020. Pursuant to the MIT Amendment, certain of our diligence obligations were extended to the provisionsecond quarter of the MIT License under which we were obligated2021, including a diligence obligation to initiatecommence a Phase 3 clinical trial for a licensed product by a specified date in the fourth quarter of 2019 is tolled until the earlier of (i) a specifiedspecific date in the second quarter of 2020 or (ii) the effective date2021. Additionally, certain of a written amendment to the MIT License. Further, pursuant to the MIT Amendment, the parties agreed to negotiate in good faith to enter into a future amendment to the MIT License subject to our providing MIT with an amended diligence plan.development and regulatory milestones and payments upon achievement of such milestones were adjusted.

In May 2014, we entered into a license agreement with 3SBio, as amended in May 2017, which we refer to as the 3SBio License. Pursuant to the 3SBio License, we were granted an exclusive license to certain pegadricase-related patents and related “know-how”know-how owned or in-licensed by 3SBio for the worldwide (except for Greater China and Japan) development and commercialization of products based thereupon for human therapeutic, diagnostic and prophylactic use. We are also granted a worldwide (except for Greater China) exclusive license to develop, commercialize and manufacture or have manufactured products combining our proprietary ImmTOR platform with pegadricase or related compounds supplied by 3SBio (or otherwise supplied if our rights to manufacture are in effect) for human therapeutic, diagnostic and prophylactic use. We were also granted a co-exclusive license to manufacture and have manufactured pegadricase and related compounds for our preclinical and clinical use or, if the 3SBio License is terminated for 3SBio’s material breach, for any use under the 3SBio License. In addition, the 3SBio License, as amended, permits us to utilize one or more third parties to provide up to 20% of our commercial supply of pegadricase. Otherwise, except in the case of a supply shortage on the part of 3SBio, we are obligated to obtain at least 80% of our supply of such compounds for Phase 3 clinical trials and commercial use from 3SBio under the terms of supply agreements to be negotiated.our separate Commercial Supply Agreement with 3SBio dated August 1, 2019.

Under the 3SBio License we have paid to 3SBio an aggregate of $3.0$7.0 million in upfront and milestone-based payments. We are required to make future payments to 3SBio contingent upon the occurrence of events related to the achievement of clinical and regulatory approval milestones of up to an aggregate of $21.0$15.0 million for products containing our ImmTOR platform, and up to an aggregate of $41.5 million for products without our ImmTOR platform. We are also required to pay 3SBio tiered royalties on annual worldwide net sales related to the pegadricase component of products at percentages ranging from the low-to-mid single digits for products containing our ImmTOR platform, and from the mid-single digits to low or low-to-mid teens for products without our ImmTOR platform, subject to specified reductions. These royalties are payable, on a country-by-country and product-by-product basis until the later of (i) the date that all of the patent rights for that product have expired in that country or (ii) a specified number of years from the first commercial sale of such product in such country.

The 3SBio License expires on the date of expiration of all of our royalty payment obligations unless earlier terminated by either party for an uncured material default of the other party or for the other party’s bankruptcy. We may also terminate the 3SBio License on a country-by-country or product-by-product basis for any reason effective upon 60 days’ prior written notice to 3SBio or, with respect to a given product, immediately upon written notice to 3SBio if we identify a safety or efficacy concern related to such product.

For our most advanced product candidate, SEL-212, we entered intoare producing ImmTOR at an approximately 400-gram scale process, which, at the doses being tested in the Phase 3 DISSOLVE program, we believe will be suitable for commercialization. The process is designed such that this same equipment is capable of potentially producing up to a cross-license agreementone-kilogram batch size scale. As our nanoparticle manufacturing process is compact, and therefore also portable, our strategy is to transfer our custom designed process skids to a contract manufacturing organization, or CMO, and have the CMO produce the nanoparticles under our direction. This is the strategy we use for production of clinical supplies for clinical trials and would be the expected strategy for commercial production.

The pegadricase enzyme for SEL-212 is produced by fermentation in E. coli and is sourced from 3SBio in China. Through a licensing arrangement, we own exclusive worldwide rights to pegadricase outside of China, with BIND Therapeutics, Inc. (formerly BIND Biosciences, Inc.), or BIND, whichco-ownership of rights in Japan and with 3SBio owning all rights in China. Under this arrangement, 3SBio has agreed to supply pegadricase for the SEL-212 program. There is also a second supplier for pegadricase in the United States.

Our AAV vector product candidates are produced using the established triple transfection production process at CMOs. We work closely with our CMOs who have platform AAV production processes that we referare able to as the BIND Agreement. Pursuantleverage for our specific AAV product candidates.

Our ImmTOR platform is designed to deliver precise instructions to the BIND Agreement, BIND granted usimmune system as a perpetual, irrevocable, royalty-free worldwide non-exclusive license under certain of BIND’s existing and future patent rights to make, have made, use, sell, offer for sale and import products and services covered by such patents and patent applications in the field of certain prophylactic and therapeutic vaccines. The time period for adding new patent rights, not included in the families of previously licensed patent rights, to our license grant from BIND has expired. Pursuant to the BIND Agreement, we granted BIND a perpetual, irrevocable, royalty-free, worldwide non-exclusive license under certain of our current and future patent rights to make, have made, use, sell, offer for sale and import products and services covered by such patents and patent applications in all other fields, in each case, excluding certain future patent rights of each party related to novel targeting agents. The time period for adding new patent rights, not included in the families of previously licensed patent rights, to BIND’s license grant from us has expired.

We endeavor to protect our nanoparticle technology, which we consider fundamental to our business, by seeking, maintaining and defending patent and other intellectual property rights, whether developed internally or licensed from third parties, relating to our program, product candidates, their methods of use and the processes for their manufacture. Our practice is to strive to protect our intellectual property by, among other methods, pursuing and obtaining patent protection in the United States and in jurisdictions outside of the United States related to our proprietary technology, inventions, improvements, programs and product candidates that are commercially important to the operation and growth of our business. We also rely on trade secrets and know-how relating to our proprietary technology, programs and product candidates, continuing innovation and continue innovating and seeking in-licensing opportunities to maintain, advance and fortify our proprietary position in our nanoparticle-based immunotherapy program and product candidates as well as to develop new programs and other product candidates. Our commercial success will depend in part on our ability to obtain and maintain patent and other proprietary protection for our program technology programs, inventions and improvements; to preserve the confidentiality of our trade secrets; to maintain our licenses to use intellectual property owned or controlled by third parties; to defend and enforce our proprietary rights, including our patents; and to operate without infringing the patents and proprietary rights of third parties.

We have developed and in-licensed numerous patents and patent applications and possess substantial know-how and trade secrets relating to our nanoparticle-based immunotherapy technology programprograms and product candidates. Our patent portfolio contains a number of issued patents in the United States and certain foreign jurisdictions. We also own a number of pending patent applications in the United States and certain foreign jurisdictions. These patents and patent applications include claims directedrelated to:

In addition, we have exclusively or non-exclusively licensed intellectual property, including U.S. issued patents, foreign issued patents, and pending applications in both the U.S. and foreign jurisdictions. The licensed patents and patent applications cover various aspects of the technology being developed by us, including claims directed to compositions of matter and methods of use, and have been filed in various countries worldwide including in North America, Europe and Asia, with material expiration dates varying from 2021 to, if claims are issued, 2028.2042. In addition to filing and prosecuting patent applications in the United States, we often file analogous patent applications in the European Union and in additional foreign countries where we believe such filing is likely to be beneficial, including but not limited to, Australia, Brazil, Canada, China, Europe, South Korea, Mexico, India, Israel, and Japan.

Each patent’s term depends upon the laws of the countries in which they are obtained. The patent term in most countries in which we file is 20 years from the earliest date of filing of a non-provisional patent application. Notably, the term of U.S. patents may be extended due to delays incurred due to compliance with FDA or by delays encountered during prosecution that are caused by the USPTO. For example, the Hatch-Waxman Act permits a patent term extension for FDA-approved drugs of up to five years beyond the expiration of the patent, depending upon the length of time the drug is under regulatory review. There is a limit to the amount of time a patent may be extended in the United States; no patent extension can extend the remaining term of a patent beyond a total of 14 years from the date of product approval and only one patent applicable to an approved drug may be extended. Similar patent term extensions are available in Europe and other jurisdictions for patents that cover regulatory-approved drugs. Currently, we own or license patents and patent applications with expected material expiration dates ranging from 20212032 to 2039.2042. However, the actual patent protection period 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 regulatory-related extensions, the availability of legal remedies in a particular country and the validity and enforceability of the patent.

The biotechnology and pharmaceutical industries are characterized by rapidly advancing technologies, intense competition and a strong emphasis on proprietary products. We face potential competition from many different sources, including pharmaceutical and biotechnology companies, academic institutions and governmental agencies and public and private research institutions. Product candidates that we successfully develop and commercialize may compete with existing therapies and new therapies that may become available in the future.

Our competitors may have significantly greater financial resources, established presence in the market, expertise in research and development, manufacturing, preclinical and clinical testing, obtaining regulatory approvals and reimbursement and marketing approved products than we do. These competitors also compete with us in recruiting and retaining qualified scientific, sales, marketing and management personnel, establishing clinical trial sites and patient registration for clinical trials, as well as in acquiring technologies complementary to, or necessary for, our programs. Smaller or early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies.

The key competitive factors affecting the success of SEL-212, and any other tolerance or immune stimulationmodulation product candidates that we develop, if approved, are likely to be their efficacy, safety, convenience, price, the level of generic competition and the availability of reimbursement from government and other third-party payors.

Our commercial opportunity could be reduced or eliminated if our competitors develop and commercialize products that are more effective, have fewer or less severe side effects, are more convenient or are less expensive than any products that we may develop. Our competitors also may obtain FDA or other regulatory approval for their products more rapidly than we may obtain approval for ours. In addition, our ability to compete may be affected in many cases by insurers or other third-party payors seeking to encourage the use of generic or biosimilar products.

Large companies with active research to prevent the formation of ADAs and treat allergies or autoimmune diseases include Eli Lilly, Roche Holding AG, Sanofi S.A., Pfizer Inc., or Pfizer, and Merck & Co., Inc., or Merck. Small, early-stage biopharmaceutical companies active in the research for new technologies to induce antigen-specific immune tolerance include Anokion SA, AnTolRx Inc., Apitope International NV, Caladrius Biosciences, Cour Pharmaceutical Development Company, Inc., Cue Biopharma, Dendright International, Inc., Parvus Therapeutics, REGiMMUNE Corporation, Rubius Therapeutics, Inc., Tolerion, Inc., Topas Therapeutics GmbH, SQZ Biotechnologies and Txcell SA. However, we believe that mostBiopharmaceutical companies active in the research for MMA include LogicBio, Poseida, and Moderna. Biopharmaceutical companies active in the research for Ornithine transcarbamylase include Ultragenyx, Poseida, TranslateBio, Arcturus, and Kaleido. Biopharmaceutical companies active in the research for IgA nephropathy include Omeros, Travere, EMD Serono, Novartis, Ionis, Visterra, Reata, and Alnylam. Biopharmaceutical companies active in the PBC research include Intercept Pharmaceuticals, Genfit, GenKyoTex, GSK, Eli Lilly, and CymaBay. Biopharmaceutical companies active in the IL-2 research include Roche Holding AG, Amgen, Bristol Myers Squibb, Eli Lilly, and Moderna.

Government authorities in the United States, at the federal, state and local level, and in other countries extensively regulate, among other things, the research, development, testing, manufacturing, quality control, approval, labeling, packaging, storage, record-keeping, promotion, advertising, distribution, post-approval monitoring and reporting, marketing and export and import of products such as those we are developing.

Our most advanced product candidate, SEL-212 is subject to regulation in the United States as a combination product. If marketed individually, each component would be subject to different regulatory pathways and would require approval of independent marketing applications by the FDA. A combination product, however, is assigned to a Center that will have primary jurisdiction over its regulation based on a determination of the combination product’s primary mode of action, which is the single mode of action that provides the most important therapeutic action. In the case of our SEL-212, we believe that the

Biological products are subject to regulation under the Federal Food, Drug, and Cosmetic Act, or FD&C Act, and the Public Health Service Act, or PHS Act, and other federal, state, local and foreign statutes and regulations. SEL-212 and any other product candidates that we develop must be approved by the FDA before they may be legally marketed in the United States and by the appropriate foreign regulatory agency before they may be legally marketed in foreign countries.

The process required by the FDA before a biologic, including a gene therapy, may be marketed in the United States generally involves the following:is summarized below.

completion of extensive nonclinicalBiological product candidates are preclinically tested before any testing sometimes referred to as preclinical testing, including laboratoryis done in humans. These tests, animal trials and formulation studies in accordance with applicable regulations, including good laboratory practices, or GLPs, and applicable requirements for humane use of laboratory animals;

The clinical study sponsor must submit the results of the preclinical tests, together with manufacturing information, analytical data, any available clinical data or literature and a proposed clinical protocol, to the FDA as part of the IND. Some preclinical testingIND which must become effective before human clinical trials may continue even after the IND is submitted.begin. The IND automatically becomes effective 30 days after receipt by the FDA, unless the FDA places the clinical study on a clinical hold within that 30-day time period. In such a case, the IND sponsor and the FDA must resolve any outstanding concerns before the clinical study can begin. The FDA may also impose clinical holds on a biological product candidate at any time before or during clinical trials due to safety concerns or non-compliance. If the FDA imposes a clinical hold, trials may not recommence without FDA authorization and then only under terms authorized by the FDA.

Clinical trials involve the administration of the biological product candidate to healthy volunteers or patients under the supervision of qualified investigators, generally physicians not employed by or under the study sponsor’s control. Clinical trials are conducted under protocols detailing, among other things, the objectives of the clinical study, dosing procedures, patient selection and exclusion criteria, and the parameters to be used to monitor patient safety, including stopping rules that assure a clinical study will be stopped if certain adverse events should occur.safety. Each protocol and any amendments to the protocol must be submitted to the FDA as part of the 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 patientssubjects provide informed consent. Further, each clinical study must be reviewed and approved by an independent institutional review board, or IRB, at or

Post-approval clinical trials, sometimes referred to as Phase IV4 clinical trials, may be conducted after initial marketing approval. These clinical trials are usedapproval to gain additional experience from the treatment of patients in the intended therapeutic indication, particularly for long-term safety follow-up.

The FDA or the sponsor or its data safety monitoring board may suspend a clinical study at any time on various grounds, including a finding that the research patients or patients are being exposed to an unacceptable health risk.grounds. Similarly, an IRB can suspend or terminate approval of a clinical study at its institution if the clinical study 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.

There are also requirements governing the reporting of ongoing clinical trials and completed clinical trial results to public registries. Sponsors of clinical trials of FDA-regulated products, including biologics, are also required to register and disclose certain clinical trial information, which is publicly available at www.clinicaltrials.gov. Concurrent with clinical trials, companies usually complete additional animal trials and must also develop additional information about the physical characteristics of the biological product candidate as well as finalize a process for manufacturing the product in commercial quantities in accordance with GMP requirements.

After the completion of clinical trials of a biological product candidate, FDA approval of a BLA must be obtained before commercial marketing of the biological product. The BLA must include results of product development, laboratory and animal trials, human trials, information on the manufacture and composition of the product, proposed labeling and other relevant information. In addition, under the Pediatric Research Equity Act, or PREA, a BLA or supplement to a BLA must contain data to assess the safety and effectiveness of the biological product candidate for the claimed indications in all relevant pediatric subpopulations and to support dosing and administration for each pediatric subpopulation for which the product is safe and effective. The Food and Drug Administration Safety and Innovation Act, or FDASIA, requires that a sponsor who issponsors planning to submit a marketing applicationBLA for a drug or biological product that includes a new active ingredient, new indication, new dosage form, new dosing regimen or new route of administrationin certain circumstances n submit an initial Pediatric Study Plan, or PSP, within sixty days after a Type C meeting or as may be agreed between the sponsor and FDA. Unless otherwise required by regulation, PREA does not apply to any biological product for an indication for which orphan designation has been granted.

Under the Prescription Drug Fee User Fee Act, or PDUFA, as amended, each BLA must be accompanied by a user fee. The FDA adjusts the PDUFA user fees on an annual basis. Fee waiverswaiver or reductions are available inunder certain circumstances, including a waiver of the application fee for the first application filed by a small business. Additionally,In addition, no user fees are assessed on BLAs foron products designated as orphan drugs unless the product also includes a non-orphan indication.

Within 60 days following submission of the application, the FDA reviews a BLA submitted to determine if it is substantially complete before the agency accepts it for filing.completeness. The FDA may refuse to file any BLA that it deems incomplete or otherwise not properly reviewable at the time of submission and may request additional information. In this event, the BLA must be resubmitted with the additional information. Once the submission is accepted for filing, the FDA begins an in-depth substantive review of the BLA. The FDAsubstantively reviews the BLA to determine, among other things, whether the proposed product is safe, pure and potent, for its intended use and whether the product is being manufactured in accordance with cGMP requirements to assure and preserve the product’s identity, safety, strength, quality, potency and purity.requirements. 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 non-binding 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.on approval. During the biological product approval process, the FDA also will determine whether a Risk Evaluation and Mitigation Strategy, or REMS, is necessary to assure the safe use of the biological

Before approving a BLA, the FDA will inspect the facilities atin which the product is manufactured. The FDA will not approve the product unless it determines thatmanufactured to determine whether the manufacturing processes and facilities are in compliance with cGMP requirements and adequate to assure consistent production ofGMPs. The FDA may also audit the product within required specifications. Additionally, before approving a BLA, the FDA will typically inspect one or more clinical investigation sites to assuredetermine that thethey have complied with good clinical trials were conducted in compliance with IND study requirements and GCP requirements.practices.

Notwithstanding the submission of relevant data and information, the FDA may ultimately decide that the BLA does not satisfy its regulatory criteria for approval and deny approval. Data obtained from clinical trials are not always conclusive and the FDA may interpret data differently than the applicant interprets the same data. If the FDA decides not to approve thedenies approval of a BLA in its presentthen-current form, the FDA will issue a complete response letter that usually describes all of the specificdetailing deficiencies in the BLA identified by the FDA. Additionally, the complete response letter may include recommended actions that the applicant might take to place the application in a condition for approval.application. If a complete response letter is issued, the applicant may either resubmit the BLA, addressing all of the deficiencies identified in the letter, or withdraw the application.

ThePrior to the submission of a BLA, the FDA may grant orphan designation to drugs or biologics intended to treat a rare disease or condition that affects fewer than 200,000 individuals in the United States, or if it affects more than 200,000 individuals in the United States, there is no reasonable expectation that the cost of developing and marketing the product for this type of disease or condition will be recovered from sales in the United States. Orphan designation must be requested before submitting a BLA.States After the FDA grants orphan designation, the identity of the therapeutic agent and its potential orphan use are disclosed publicly by the FDA. Orphan designation does not convey any advantage in or shorten the duration of the regulatory review and approval process.

In the United States, orphan designation entitles a party to financial incentives such as opportunities for grant funding towards clinical trial costs, tax advantages and user-fee waivers. In addition, if a product receives the first FDA approval for the indication for which it has orphan designation, the product is entitled to orphan exclusivity, which means the FDA may not approve any other application to market the same product for the same indication for a period of seven years, except in limited circumstances, such as a showing of clinical superiority over the product with orphan exclusivity or where the manufacturer with orphan exclusivity is unable to assure sufficient quantities of the approvedapprove orphan designated product. Competitors, however, may

The Rare Pediatric Disease designation program allows for oura sponsor who receives an approval for a product candidates, but depending on the proposed indicationto potentially qualify for which we intenda voucher that can be redeemed to develop our future products, we may in the future request such designation.receive a priority review of a subsequent marketing application for a different product.

The FDA has a Fast Track program that is intended to expedite or facilitate the process for reviewing new biological products that meet certain criteria. Specifically, new biological products are eligible for Fast Track designation if they are intended to treat a serious or life-threatening disease or condition and demonstrate the potential to address unmet medical needs for the disease or condition. Fast Track designation applies to the combination of the product and the specific indication for which it is being studied. The sponsor of a new biologic may request that the FDA designate the biologic as a Fast Track product at any time during the clinical development of the product. The FDA may consider for review sections of the marketing application for a Fast Track product on a rolling basis before the complete application is submitted, if the sponsor provides a schedule for the

Any product submitted to the FDA for marketing, including under a Fast Track program, may be eligible for other types of FDA programs intended to expedite development and review, such as priority review and accelerated approval. Any product is eligible for priority review if it treats a serious condition and, if approved, would provide a significant improvement in safety or effectiveness compared to marketed products. The FDA will attempt to direct additional resources to the evaluation of an application for a new biological product designated for priority review in an effort to facilitate the review. Additionally, a product may be eligible for accelerated approval. Biological products studied for their safety and effectiveness in treating serious or life-threatening illnesses and that provide meaningful therapeutic benefit over existing treatments may be eligible for accelerated approval, which means that they may be approved on the basis of adequate and well-controlled clinical studies establishing that the product has an effect on a surrogate endpoint that is reasonably likely to predict a clinical benefit, or on the basis of an effect on a clinical endpoint other than survival or irreversible morbidity or 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 biological product subject to accelerated approval perform adequate and well-controlled post-marketing clinical studies.studies to confirm such benefit. In addition, the 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. Fast Track designation, priority review and accelerated approval do not change the standards for approval but may expedite the development or approval process.

In addition, under the provisions of FDASIA, the FDA established a Breakthrough Therapy Designation which is intended to expedite the development and review of products that treat serious or life-threatening diseases or conditions. A breakthrough therapy is defined as a drug that is intended, alone or in combination with one or more other drugs, to treat a serious or life-threatening disease or condition, and preliminary clinical evidence indicates that the drug may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. The designation includes all of the features of Fast Track designation, as well as more intensive FDA interaction and guidance. The Breakthrough Therapy Designation is a distinct status from both accelerated approval and priority review, but these can also be granted to the same product candidate if the relevant criteria are met. The FDA must take certain actions, such as holding timely meetings and providing advice, intended to expedite the development and review of an application for approval of a breakthrough therapy. Requests for breakthrough therapy designation will be reviewed within 60 days of receipt, and FDA will either grant or deny the request.

Maintaining substantial compliance with applicable federal, state and local statutes and regulations requires the expenditure of substantial time and financial resources. Rigorous and extensive FDA regulation of biological products continues after approval, particularly with respect to cGMP requirements. Manufacturers of our products are required to comply with applicable requirements in the cGMP regulations, including quality control and quality assurance and maintenance of records and documentation. Other post-approval requirements applicable to biological products include record-keeping requirements, reporting of adverse effects and reporting updated safety and efficacy information.

We also must comply with the FDA’s advertising and promotion requirements, such as those related to direct-to-consumer advertising, the prohibition on promoting products for uses or in patient populations that are not described in the product’s approved labeling (known as “off-label use”), industry-sponsored scientific and educational activities and promotional activities involving the internet. Discovery of previously unknown problems or the failure to comply with the applicable regulatory requirements may result in restrictions on the marketing of a product or withdrawal of the product from the market as well as possible civil or criminal sanctions. Failure to comply with the applicable U.S. requirements at any time during the product development process, approval process or after approval, may subject an applicant or manufacturer to administrative or judicial civil or criminal sanctions and adverse publicity. FDA sanctions could include refusal to approve pending applications, withdrawal of an approval, clinical hold, warning or untitled letters, product recalls, product seizures, total or partial suspension of production or distribution, injunctions, fines, refusals of government contracts, mandated corrective advertising or communications with doctors, debarment, restitution, disgorgement of profits, or civil or criminal penalties.

The Patient Protection and Affordable Care Act, or ACA, signed into law on March 23, 2010, includes a subtitle called the Biologics Price Competition and Innovation Act of 2009, or BPCIA, which created an abbreviated approval pathway for biological products that are biosimilar to or interchangeable with an FDA-licensed reference biological product.

Biosimilarity, which requires that there be no clinically meaningful differences between the biological product and the reference product in terms of safety, purity and potency, can be shown through analytical studies, animal studies and a clinical study or studies. Interchangeability requires that a product is biosimilar to the reference product and the product must demonstrate 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 biologic and the reference biologic 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 biologic. However, 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 to implementation of the abbreviated approval pathway that are still being worked out by the FDA.

Under the BPCIA, an application for a biosimilar product may not be submitted to the FDA until four years following the date that the reference product was first licensed by the FDA. In addition, the approval of a biosimilar product may not be made effective by the FDA until 12 years from the date on which the reference product was first licensed. During this 12-year period of exclusivity, another company may still market a competing version of the reference product if the FDA approves a full BLA for the competing product containing the sponsor’s own preclinical data and data from adequate and well-controlled clinical trials to demonstrate the safety, purity and potency of their product. The BPCIA also created certain exclusivity periods for certain 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.

The BPCIA is complex and continues to be interpreted and implemented by the FDA. As a result, the ultimate impact, implementation and meaning of the BPCIA is subject to significant uncertainty.

Whether or not we obtain FDA approval for a product, we must obtain the requisite approvals from regulatory authorities in foreign countries prior to the commencement of clinical studies or marketing of the product in those countries. Certain countries outside of the United States have a similar process that requires the submission of a clinical study application much like the IND prior to the commencement of human clinical studies. In the European Union, for example, a clinical trial authorization, or CTA, must be submitted to each country’s national health authority and an independent ethics committee, much like the FDA and the IRB, respectively. Once the CTA is approved in accordance with a country’s requirements, clinical study development may proceed.

The requirements and process governing the conduct of clinical studies, product licensing, pricing and reimbursement vary from country to country. In all cases, the clinical studies are conducted in accordance with GCP and the applicable regulatory requirements and the ethical principles that have their origin in the Declaration of Helsinki.

In the European Economic Area, or EEA, which is composed of the 27 Member Statesmember states of the European Union plus Norway, Iceland and Liechtenstein and the United Kingdom (until the end of the transition period on 31 December 2020 provided for in Withdrawal Agreement between the EU and the UK) medicinal products can only be commercialized after obtaining a Marketing Authorization, or MA.

There are two types of MAs.

To obtain regulatory approval of an investigational biological product under European Union regulatory systems, we must submit a marketing authorization application, which is similar to the U.S. BLA. The European Union also provides opportunities for market exclusivity. For example, in the European Union, uponUpon receiving marketing authorization, new chemical entities generally receive eight years of data exclusivity, and an additional two years of market exclusivity. If granted, data exclusivitywhich prevents regulatory authorities in the European Union from referencing the innovator’s data to assess a generic or biosimilar application. During theapplication, and an additional two-year periodtwo years of market exclusivity, a generic marketing authorization can be submitted, and the innovator’s data may be referenced, butduring which no generic or biosimilar product can be marketed until the expiration of the market exclusivity.marketed. However, there is no guarantee that a product will be considered by the European Union’s regulatory authorities to be a new chemical entity, and products may not qualify for data exclusivity. Products receiving orphan designation in the European Union can receive ten years of market exclusivity, during which time no marketing authorization application shall be accepted, and no marketing authorization shall be granted for a similar medicinal product for the same indication. An orphan product can also obtain an additional two years of market exclusivity in the European Union for pediatric

The criteria for designating an “orphan medicinal product” in the European Union are similar in principle to those in the United States. Under Article 3 of Regulation (EC) 141/2000, a medicinal product may be designated as orphan if (1) it is intended for the diagnosis, prevention or treatment of a life-threatening or chronically debilitating condition; (2) either (a) such condition affects no more than five in 10,000 persons in the European Union when the application is made, or (b) the product, without the benefits derived from orphan status, would not generate sufficient return in the European Union to justify investment; and (3) there exists no satisfactory method of diagnosis, prevention or treatment of such condition authorized for marketing in the European Union, or if such a method exists, the product will be of significant benefit to those affected by the condition, as defined in Regulation (EC) 847/2000. Orphan medicinal products are eligible for certain financial incentives such as reduction of fees or fee waivers and are, upon grant of a marketing authorization, entitled to ten years of market exclusivity for the approved therapeutic indication. The application for orphan drug designation must be submitted before the application for marketing authorization. The applicant will receive a fee reduction for the marketing authorization application if the orphan drug designation has been granted, but not if the designation is still pending at the time the marketing authorization is submitted. Orphan drug designation does not convey any advantage in, or shorten the duration of, the regulatory review and approval process.

For other countries outside of the European Union, such as countries in Eastern Europe, Latin America or Asia, the requirements governing the conduct of clinical studies, product licensing, pricing and reimbursement vary from country to

When conducting clinical trials in the EU, we must adhere to the provisions of the European Union Clinical Trials Directive (Directive 2001/20/EC) and the laws and regulations of the EU Member States implementing them. These provisions require, among other things, that the prior authorization of an Ethics Committee and the competent Member State authority is obtained before commencing the clinical trial. In April 2014, the EU passed the Clinical Trials Regulation (Regulation 536/2014), which will replace the current Clinical Trials Directive. ToDirective, to ensure that the rules for clinical trials are identical throughout the European Union, the EU Clinical Trials Regulation was passed as a regulation that is directly applicable in all EU member states. All clinical trials performed in the European Union are required to be conducted in accordance with the Clinical Trials Directive until the Clinical Trials Regulation becomes applicable. According to the current plans of the EMA, the Clinical Trials Regulation is expected to become applicable in 2020.Union.

We are also subject to data privacy and security laws in the jurisdictions outside of the U.S. in which we are established, run clinical trials or in which we sell or market our products once approved. For example, in Europe we are subject to Regulation (EU) 2016/679 (General Data Protection Regulation or GDPR) in relation to our collection, control, processing and other use of personal data (i.e. data relating to an identifiable living individual). We process personal data in relation to participants in our clinical trials in the EEA., including the health and medical information of these participants. The GDPR is directly applicable in each E.U. Member State, however, it provides that E.U. Member States may introduce further conditions, including limitations which could limit our ability to collect, use and share personal data (including health and medical information), or could cause our compliance costs to increase, ultimately having an adverse impact on our business. The GDPR imposes onerous accountability and transparency obligations requiring data controllers and processors to maintain a record of their data processing and implement policies as part of its mandated privacy governance framework. It also requires data controllers to be transparent and disclose to data subjects (in a concise, intelligible and easily accessible form) how theirregarding personal information is to be used, imposes limitations on retention of personal data; defines for the first time pseudonymized (i.e., key-coded) data; introduces mandatory data breach notification requirements; and sets higher standards for data controllers to demonstrate that they have obtained valid consent for certain data processing activities.data. We are also subject to E.U. rules with respect to cross-border transfers of personal data out of the E.U. and EEA. We are subject to the supervision of local data protection authorities in those E.U. jurisdictions where we are established or otherwise subject to the GDPR. Fines for certain breaches of the GDPR are significant: up to the greater of EUR 20 million or 4% of total global annual turnover. In addition to the foregoing, aA breach of the GDPR could result in significant fines, regulatory investigations, reputational damage, orders to cease/ change our use of data, enforcement notices, as well potential civil claims including class action type litigation where individuals suffer harm. Moreover, the United Kingdom leaving the E.U. could also lead to further legislative and regulatory changes. It remains unclear how the United Kingdom data protection laws or regulations will develop in the medium to longer term and how data transfer to the United Kingdom from the E.U. will be regulated, especially following the United Kingdom's departure from the E.U. on January 31, 2020 without a deal.regulated. However, the United Kingdom has transposed the GDPR into domestic law with the Data Protection Act 2018, which remains in force following the United Kingdom'sKingdom’s departure from the EU.

The federal Anti-Kickback Statute prohibits, among other things, any person or entity from knowingly (regardless of knowledge of this specific statute) and willfully offering, paying, soliciting, receiving or providing any remuneration, directly or indirectly, overtly or covertly, to induce or in return for purchasing, leasing, ordering, or arranging for or recommending the purchase, lease, or order of any item or service reimbursable, in whole or in part, under Medicare, Medicaid or other federal healthcare programs. The term “remuneration” has been broadly interpreted to include anything of value. The Anti-Kickback Statute has been interpreted to apply to arrangements between pharmaceutical manufacturers on the one hand and prescribers, purchasers and formulary managers on the other. In addition, a person or entity does not need to have actual knowledge of the statute or specific intent to violate it in order to have committed a violation. The majority of states also similar have anti-kickback laws, which establish similar prohibitions and in some cases may apply to items or services reimbursed by any third-party payor, including commercial insurers.are more restrictive.

The federal false claims and civil monetary penalties laws, including the civil False Claims Act, prohibit any person or entity from, among other things, knowingly presenting, or causing to be presented, a false, fictitious or fraudulent claim for payment to, or approval by, the federal government or knowingly making, using, or causing to be made or used a false record or statement material to a false or fraudulent claim to the federal government, or from knowingly making a false statement to

The federal Health Insurance Portability and Accountability Act of 1996, or HIPAA, prohibits, among other actions, knowingly and willfully executing, or attempting to execute, a scheme to defraud any healthcare benefit program, including private third-party payors, knowingly and willfully embezzling or stealing from a healthcare benefit program, willfully obstructing a criminal investigation of a healthcare offense, and knowingly and willfully falsifying, concealing or covering up a material fact or making any materially false, fictitious or fraudulent statement in connection with the delivery of or payment for healthcare benefits, items or services. A person or entity does not need to have actual knowledge of the statute or specific intent to violate it in order to have committed a violation.

In addition, there has been a recent trend of increased federal and state regulation of payments made to physicians and certain other healthcare providers. The ACA imposed, among other things, new annual reporting requirements through the Physician Payments Sunshine Act for covered manufacturers for certain payments and “transfers of value” provided to physicians (defined to include doctors, dentists, optometrists, podiatrists and chiropractors), certain other health care professionals beginning in 2022, and teaching hospitals, as well as ownership and investment interests held by physicians and their immediate family members. Failure to submit timely, accurately and completely the required information for all payments, transfers of value and ownership or investment interests may result in civil monetary penalties. In addition, certain states require implementation of compliance programs and compliance with the pharmaceutical industry’s voluntary compliance guidelines and the relevant compliance guidance promulgated by the federal government, impose restrictions on marketing practices, and/or tracking and reporting of pricing information and marketing expenditure as well as gifts, compensation and other remuneration or items of value provided to physicians and other healthcare professionals and entities.

We may also be subject to data privacy and security regulation by both the federal government and the states in which we conduct our business. HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act, or HITECH, and their respective implementing regulations, impose specified requirements relating to the privacy, security and transmission of individually identifiable health information held by covered entities and their business associates. Among other things, HITECH made HIPAA’s security standards directly applicable to, as well as imposed certain other privacy obligations on, “business associates,” defined as independent contractors or agents of covered entities that create, receive, maintain or transmit protected health information in connection with providing a service for or on behalf of a covered entity. HITECH also increased the civil and criminal penalties that may be imposed against covered entities, business associates and possibly other persons, and gave state attorneys general new authority to file civil actions for damages or injunctions in federal courts to enforce the federal HIPAA laws and seek attorney’s fees and costs associated with pursuing federal civil actions. Even when HIPAA does not apply, according to the Federal Trade Commission or the FTC, failing to take appropriate steps to keep consumers’ personal information secure constitutes unfair acts or practices in or affecting commerce in violation of Section 5(a) of the Federal Trade Commission Act, or the FTCA, 15 U.S.C § 45(a). The FTC expects a company’s data security measures to be reasonable and appropriate in light of the sensitivity and volume of consumer information it holds, the size and complexity of its business, and the cost of available tools to improve security and reduce vulnerabilities. Individually identifiable health information is considered sensitive data that merits stronger safeguards. The FTC’s guidance for appropriately securing consumers’ personal information is similar to what is required by the HIPAA Security Rule.

Significant uncertainty exists as to the coverage and reimbursement status of any pharmaceutical or biological products for which we obtain regulatory approval. In the United States and markets in other countries, patients who are prescribed treatments for their conditions and providers performing the prescribed services generally rely on third-party payors to reimburse all or part of the associated healthcare costs. Patients are unlikely to use our products unless coverage is provided and reimbursement is adequate to cover a significant portion of the cost of our products. Moreover, for drugs and biologics administered under the supervision of a physician, obtaining coverage and adequate reimbursement may be particularly difficult because of the higher prices often associated with such products. Sales of any products for which we receive regulatory approval for commercial sale will therefore depend, in part, on the availability of coverage and adequate reimbursement from third-party payors. Third-party payors include government authorities, managed care plans, private health insurers and other organizations.

The process for determining whether a third-party payor will provide coverage for a pharmaceutical or biological product typically is separate from the process for setting the price of such product or for establishing the reimbursement rate that the payor will pay for the product once coverage is approved. Third-party payors may limit coverage to specific products on an approved list, also known as a formulary, which might not include all of the FDA-approved products for a particular indication. A decision by a third-party payor not to cover our product candidates could reduce physician utilization of our products once approved and have a material adverse effect on our sales, results of operations and financial condition. Moreover, a third-party payor’s decision to provide coverage for a pharmaceutical or biological product does not imply that an adequate reimbursement rate will be approved. Adequate third-party reimbursement may not be available to enable us to maintain price levels sufficient to realize an appropriate return on our investment in product development. Additionally, coverage and reimbursement for products can differ significantly from payor to payor. One third-party payor’s decision to cover a particular medical product or service does not ensure that other payors will also provide coverage for the medical product or service, or will provide coverage at an adequate reimbursement rate.

A primary trend in the U.S. healthcare industry and elsewhere is cost containment. Government authorities and other third-party payors have attempted to control costs by limiting coverage and the amount of reimbursement for particular medical products. For example, the ACA, among other things, increased the minimum Medicaid rebates owed by most manufacturers under the Medicaid Drug Rebate Program; introduced a new methodology by which rebates owed by manufacturers under the Medicaid Drug Rebate Program are calculated for drugs that are inhaled, infused, instilled, implanted or injected; extended the Medicaid Drug Rebate Program to utilization of prescriptions of individuals enrolled in Medicaid managed care plans; subjected drug manufacturers to new annual fees based on pharmaceutical companies’ share of sales to federal healthcare programs; and created a new Patient Centered Outcomes Research Institute to oversee, identify priorities in, and conduct comparative clinical effectiveness research, along with funding for such research.

In addition, other legislative changes have been proposed and adopted in the United States since the ACA was enacted. This included aggregate reductions of Medicare payments to providers of 2% per fiscal year, which went into effect on April 1, 2013,

At Selecta Biosciences, we consider human capital to be an essential driver of our business and federal healthcare reform measures will be adopted in the future, any of which could limit the amounts that federalsuccessful strategy creation and state governments will payexecution. Our people, driven by our Collaborative, Pioneering, and Patient Focused culture, propel our business forward, strengthening us for healthcare products and services, which could result in reduced demand for our products once approved or additional pricing pressures. The implementation of cost containment measures or other healthcare reforms may prevent us from being able to generate revenue, attain profitability or commercialize our drugs.

As of JanuaryDecember 31, 2020,2021, we had 39 full-time58 employees, 2744 of whom wereare primarily engaged in research and development activities. A total of 12 employees have either one or both an M.D. or Ph.D. degree. Noneactivities and 14 in corporate functions. 66% of our employees have at least one of a Masters, PhD, or MD degree. Our 2021 annualized voluntary turnover rate was 12.87%. All employees reside and work in the United States and are not represented by a labor union and weunion. We consider our employee relations to be good.strong and in good standing.

We file electronically with the SEC our annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K, proxy statements and other information. Our SEC filings are available to the public over the Internet at the SEC's website at http://www.sec.gov. We make available on our website at www.selectabio.com, under “Investors,” free of charge, copies of these reports as soon as reasonably practicable after filing or furnishing these reports with the SEC. The hyperlink to our website is included as an inactive textual reference only, and the information on our website is not incorporated by reference in this Annual Report on Form 10-K or in any other filings we make with the SEC.

Since inception, we have incurred significant operating losses in every year. Our net loss was $55.4losses were $25.7 million for the year ended December 31, 20192021, and $65.3$68.9 million and $55.4 million for each of the years ended December 31, 20182020 and 2017,2019, respectively. As of December 31, 2019,2021, we had an accumulated deficit of $335.8$430.3 million. To date, we have financed our operations primarily through the public offeringofferings and private placements of our securities, funding received from research grantscollaboration and collaborationlicense arrangements and our credit facility. We currently have no source of product revenue, and we do not expect to generate product revenue for the foreseeable future. All of our revenue to date has been collaboration and grant revenue. We have devoted substantially all of our financial resources and efforts to developing our ImmTOR platform, identifying potential product candidates and conducting preclinical studies and our clinical

To become and remain profitable, we must succeed in developing and eventually commercializing products that generate significant revenue. This will require us to be successful in a range of challenging activities, including completing preclinical testing and clinical trials of our product candidates, discovering additional product candidates, obtaining regulatory approval and securing reimbursement for these product candidates, manufacturing, marketing and selling any products for which we may obtain regulatory approval, and establishing and managing our collaborations at various stages of a product candidate’s development. We are only in the preliminary stages of most of these activities. We may never succeed in these activities and, even if we do, may never generate revenues that are significant enough to achieve profitability.

Because of the numerous risks and uncertainties associated with pharmaceutical and biological product development, we are unable to accurately predict the timing or amount of increased expenses or when, or if, we will be able to achieve profitability. If we are required by the FDA or other regulatory authorities to perform studies in addition to those currently expected, or if there are any delays in completing our clinical trials or the development of any of our product candidates, our expenses could increase and product revenue could be further delayed.

Even if we do achieve profitability, we may not be able to sustain or increase profitability on a quarterly or annual basis. Our failure to become and remain profitable would depress our value and could impair our ability to raise capital, expand our business, maintain our research and development efforts, diversify our product offerings or continue our operations.

We expect our expenses to increase in connection with our ongoing activities, particularly as we conduct our clinical trials of SEL‑212, continue to develop our gene therapy program,pipeline, including our collaboration with AskBio, research and develop our autoimmune programs and advance the evolution of our ImmTOR platform in combination with IL-2, and continue research and development for our other product candidates. In addition,Additionally, if we obtain regulatory approval for any of our product candidates, we expect to incur significant commercialization expenses related to product manufacturing, marketing, sales and distribution. Accordingly, we will need to obtain substantial additional funding to continue operations. If we are unable to raise capital when needed or on attractive terms, we could be forced to delay, reduce or eliminate our clinical trials, our other research and development programs or any future commercialization efforts.

We believe that our existing cash, cash equivalents investments, and restricted cash as of December 31, 20192021 will enable us to fund our operating expenses and capital expenditure requirementscurrent planned operations into the firstthird quarter of 2021. We plan2023, though we may realize additional cash resources upon the achievement of certain contingent collaboration milestones or it may pursue additional cash resources through public or private equity or debt financings or by establishing collaborations with other companies. Management’s expectations with respect to commence our Phase 3 clinical program in SEL-212 in the second halfability to fund current and long-term planned operations are based on estimates that are subject to risks and uncertainties. If actual results are different from management’s estimates, we may need to seek additional strategic or financing opportunities sooner than would otherwise be expected. However, there is no guarantee that any collaboration milestones will be achieved or that any of 2020. Becausethese strategic or financing opportunities will be executed on favorable terms, and some could be dilutive to existing stockholders. If we are unable to obtain additional funding on a timely basis, we may be forced to significantly curtail, delay, or

Our future capital requirements will depend on many factors, including:

Any additional fundraising efforts may divert our management from their day‑to‑dayday-to-day activities, which may adversely affect our ability to develop and commercialize our product candidates. In addition, we cannot guarantee that future financing will be available in sufficient amounts or on terms acceptable to us, if at all. Market volatility resulting from the COVID-19 pandemic or other factors could also adversely impact our ability to access capital as and when needed. Moreover, the terms of any financing may adversely affect the holdings or the rights of our stockholders, and the issuance of additional securities, whether equity or debt, by us, or the possibility of such issuance, may cause the market price of our shares to decline. The sale of additional equity or convertible securities would dilute all of our stockholders. The incurrence of indebtedness could result in increased fixed payment obligations and we may be required to agree to certain restrictive covenants, such as limitations on our ability to incur additional debt, limitations on our ability to acquire, sell or license intellectual property rights and other operating restrictions

If we are unable to obtain funding on a timely basis, we may be required to significantly curtail, delay or discontinue one or more of our research or development programs, including our clinical trial programs, or the commercialization of any product candidates, or be unable to sustain or expand our operations or otherwise capitalize on our business opportunities, as desired, which could materially affect our business, financial condition and results of operations.

On September 12, 2017,August 31, 2020, we entered into a term loan, facilityor the 2020 Term Loan, of up to $21.0$35.0 million, with Silicon Valley Bank,consisting of term loans in an aggregate amount of $25.0 million, or SVB. Thethe Term A Loan, and term loan facility isloans in an aggregate amount of $10.0 million, or the Term B Loan, governed by a loan and security agreement dated September 12, 2017, betweenamong us and Oxford Finance LLC, or Oxford, as collateral agent and a lender, and Silicon Valley Bank, or SVB, whichas a lender. The Term A Loan was funded in full on September 13, 2017. TheAugust 31, 2020, the proceeds of which were used to repay our previously existing 2017 term loan facility with SVBand for general corporate and working capital purposes, and the draw period relating to the Term B Loan expired on September 30, 2021.

The 2020 Term Loan is secured by a lien on substantially all of our assets, other than intellectual property, provided that such lien on substantially all assets includes any rights to payments and proceeds from the sale, licensing or disposition of intellectual property. We also granted SVBOxford a negative pledge with respect to our intellectual property.

The term loan facility contains customaryFailure to satisfy our current and future debt obligations, including covenants and representations, including but not limited to financial reporting obligations and limitations on dividends, indebtedness, collateral, investments, distributions, transfers, mergerstake or acquisitions, taxes, corporate changes, deposit accounts, and subsidiaries. The term loan facility also contains other customary provisions, such as expense reimbursement, non-disclosure obligations as well as indemnification rights for the benefit of SVB. The events of defaultavoid specific actions, under the term loan facility include, but are not limited to, our failure to make any payments of principal or interest under the term loan facility or other transaction documents, our breach or default2020 Term Loan could result in the performance of any covenant under the

We have net operating loss carryforwards, or NOLs, for federal and state income tax purposes that may be available to offset our future taxable income, if any. In general, under Sections 382 and 383 of the U.S. Internal Revenue Code of 1986, as amended, or the Code, a corporation that undergoes an “ownership change” is subject to limitations on its ability to use its pre‑changepre-change NOLs to offset future taxable income. If the U.S. Internal Revenue Service, or IRS, challenges our analysis that existing NOLs will not expire before utilization due to previous ownership changes, or if we undergo an ownership change in connection with or after a public offering, our ability to use our NOLs could be limited by Section 382 of the Code. Future changes in our stock ownership, some of which are outside of our control, could result in an ownership change under Sections 382 and 383 of the Code. Furthermore, our ability to use NOLs of companies that we may acquire in the future may be subject to limitations. As a result, we may not be able to use a material portion of the NOLs reflected on our balance sheet, even if we attain profitability. The reduction of the corporate tax rate under the TCJA may cause a reduction in the economic benefit of our NOLs and other deferred tax assets available to us. Under the TCJA, although the treatment ofcurrent law, NOLs arising on orthat arose before December 31, 2017 has generally not changed, NOLs arising on or after January 1, 2018, will generally onlybegin to expire in 2041. NOLs that arose after 2017 may be ableused to offset at most 80% of our taxable income. This changeincome to the extent not offset by pre-2018 NOLs. As a result, we may require usbecome required to pay federal income taxes in future years despite generating a losshaving generated losses for federal income tax purposes in prior years.

All of our product candidates are derived from our ImmTOR platform, which is an unproven approach to induce antigen‑specificantigen-specific immune tolerance and to mitigate the immunogenicity of biologic therapies currently being implemented to treat patients. We are primarily developing our ImmTOR platform to restore self-tolerance to autoantigens and potentially treat autoimmune diseases, to be co-administered with AAV gene therapies to potentially enable redosing of said gene therapies and improve and enable activity in biologics that are designed to treat rare(including therapeutic enzymes and serious diseases, with an initial focus on developing SEL‑212other immunogenic drugs).

While we have completed our early development clinical trials and a Phase 2 clinical trial for the treatment of chronic refractory gout. We are also leveraging our ImmTOR platform to pursue programs in additional therapeutic areas withSEL-212, we have not completed a focus on gene therapy.

The occurrence of any of the foregoing would effectively prevent or delay approval of our lead and other product candidates. The outbreak of COVID-19 may continue to adversely impact our business, including our preclinical studies and clinical trials.

Our future success depends in part on our successful development of viable gene therapy product candidates utilizing our ImmTOR platform. We may experience problems or delays in developing such product candidates and any such problems or delays (i) may result in unanticipated costs and time to develop our product candidates and/or (ii) may not be resolved in a satisfactory manner.

The regulatory approval process and clinical trial requirements for novel product candidates can be more expensive and take longer than for other, better known or more extensively studied product candidates, and we cannot predict how long it will take or how much it will cost to complete clinical developments and obtain regulatory approvals for a gene therapy product candidate in either the United States or the European Union or how long it will take to commercialize a gene therapy product candidate, if and when approved. Regulatory requirements governing gene therapy products have changed frequently and may continue to change in the future. For example, the FDA established the Office of Tissues and Advanced Therapies within its Center for Biologics Evaluation and Research, or CBER, to consolidate the review of gene therapy and related products, and the Cellular, Tissue and Gene Therapies Advisory Committee to advise CBER on its review. These and other regulatory review agencies, committees and advisory groups and the requirements and guidelines they promulgate may lengthen the regulatory review process, require us to perform additional preclinical studies or clinical trials, increase our development costs, lead to changes in regulatory positions and interpretations, delay or prevent approval and commercialization of these treatment candidates or lead to significant post-approval limitations or restrictions.

Changes in applicable regulatory guidelines may lengthen the regulatory review process for our product candidates, require additional studies or trials, increase development costs, lead to changes in regulatory positions and interpretations, delay or prevent approval and commercialization of such product candidates, or lead to significant post-approval limitations or restrictions. Additionally, adverse developments in clinical trials conducted by others of gene therapy products or products

As we advance any gene therapy product candidates, we will be required to consult with various regulatory authorities, and we must comply with applicable laws, rules, and regulations, which may change from time to time including during the course of development of our product candidates. If we fail to do so, we may be required to delay or discontinue the clinical development of certain of our product candidates. These additional processes may result in a review and approval process that is longer than we otherwise would have expected. Even if we comply with applicable laws, rules, and regulations, and even if we maintain close coordination with the applicable regulatory authorities with oversight over our product candidates, our development programs may fail to succeed. Regulatory authorities have substantial discretion in the approval process and may refuse to accept a marketing application as deficient or may decide that our data is insufficient for approval and require additional preclinical, clinical or other studies. In addition, varying interpretations of the data obtained from preclinical and clinical testing could delay, limit or prevent marketing approval of a product candidate. Additionally, adverse developments in clinical trials conducted by others of gene therapy products or products created using genome editing technology, or adverse public perception of the field of genome editing, may cause the FDA and other regulatory bodies to revise the requirements for approval of any product candidates we may develop or limit the use of products utilizing genome editing technologies, either of which could materially harm our business. Delay or failure to obtain, or unexpected costs in obtaining, the regulatory approval necessary to bring a potential product to market would materially and adversely affect our business, financial condition, results of operations and prospects.

Our lead product candidate,Except for SEL-212 was evaluated in a Phase 2 clinical program that was initiated in October 2016 and the final patient's last visit occurred in January 2019. In March 2019, we initiated COMPARE, a Phase 2 clinical trial designed to directly compare the safety, efficacy and tolerability of SEL-212 to the currently FDA-approved uricase therapy, KRYSTEXXA, for the treatment of patients with chronic refractory gout, and completedSEL 302, our targeted enrollment of the COMPARE trial in December 2019. We are preparing for the start of a pivotal Phase 3 program for SEL-212.

Before obtaining marketing approval from regulatory authorities for the sale of our product candidates, we must conduct extensive clinical trials to demonstrate the safety and efficacy of the product candidate for its intended indications. Clinical testing is expensive, difficult to design and implement, can take many years to complete and its outcome is inherently uncertain. A failed clinical trial can occur at any stage of testing. Moreover, the outcome of preclinical testing and early clinical trials may not be predictive of the success of later clinical trials, and interim results of a clinical trial do not necessarily predict final results. For example, the topline clinical trial results we reported from our Phase 2 head-to-head (COMPARE)COMPARE study of SEL-212 including

Many companies in the pharmaceutical and biotechnology industries have suffered significant setbacks in clinical trials after achieving positive results in preclinical development or early-stage clinical trials, and we cannot be certain that we will not face similar setbacks. These setbacks have been caused by, among other things, preclinical findings made while clinical trials were underway or safety or efficacy observations made in clinical trials, including adverse events. SAEs caused by, or other unexpected properties of, any product candidates that we may choose to develop could cause us, an institutional review board or regulatory authority to interrupt, delay or halt clinical trials of one or more of such product candidates and could result in a more restrictive label or the delay or denial of marketing approval by the FDA or comparable non-U.S. regulatory authorities. If any product candidate that we may choose to develop is associated with SAEs or other unexpected properties, we may need to abandon development or limit development of that product candidate to certain uses or subpopulations in which those undesirable characteristics would be expected to be less prevalent, less severe or more tolerable from a risk-benefit perspective. For example, in the SEL-403 Phase 1 clinical trial, a Grade 5 SAE (patient death) occurred that was deemed by the trial investigator to be probably related to SVP-Rapamycin and possibly related to the patient's pleural mesothelioma condition which led the Company to abandon development of SEL-403. In the SEL-212 Phase 1/2 clinical program, we have observed multiple SAEs, have occurred, and future SAEs may occur causing the Companyus to incur additional costs or experience delays in completing, or causing the Companyus to ultimately be unable to complete, the development and commercialization of our product candidates, and delay or prevent our ability to

In addition, we cannot be certain as to what type and how many clinical trials the FDA will require us to conduct before we may gain regulatory approval to market SEL-212 or any of our other product candidates in the United States or other countries, if any. Prior to approving a new therapeutic product, the FDA generally requires that safety and efficacy be demonstrated in two adequate and well-controlled clinical trials. We expect that we may need to conduct more than one Phase 3 trial for SEL-212 for a chronic refractory gout indication in order to gain approval from the FDA. Even if we conduct more than one Phase 3 trial for SEL-212, the FDA may not accept the data, and may delay, limit or deny approval of SEL-212. Additional clinical trials could cause us to incur significant development costs, delay or prevent the commercialization of SEL-212 or otherwise adversely affect our business.

We may experience numerous unforeseen events during, or as a result of, clinical trials that could delay or prevent our ability to receive marketing approval for, or commercialize, our product candidates, including:

If we are required to conduct additional clinical trials or other testing of our product candidates beyond those that we currently contemplate, if we are unable to successfully complete clinical trials of our product candidates or other testing, if the results of these trials or tests are not positive or are only modestly positive or if there are safety concerns, or if we are forced to delay or abandon certain clinical trials or other testing in order to conserve capital resources, we may:

In addition, disruptions caused by the COVID-19 pandemic may increase the likelihood that we encounter such difficulties or delays in initiating, enrolling, conducting or completing our planned and ongoing clinical trials. We could also encounter delays if a clinical trial is suspended or terminated by us, by the IRBs of the institutions in which such trials are being conducted, by a Data Safety Monitoring Board for such trial or by the FDA or comparable foreign regulatory authorities. Such authoritiesterminated. Authorities may impose such a suspension or termination due to a number of factors, including failure to conduct the clinical trial in accordance with regulatory requirements or our clinical protocols, inspection of the clinical trial operations or trial site by the FDA or comparable foreign regulatory authorities resulting in the imposition of a clinical hold, unforeseen safety issues or adverse side effects, failure to demonstrate a benefit from using a drug, changes in governmental regulations or administrative actions or lack of adequate funding to continue the clinical trial. In addition, changes in regulatory requirements and policies may occur, and we may need to amend clinical trial protocols to comply with these changes. Amendments may require us to resubmit our clinical trial protocols to IRBs for reexamination, which may impact the costs, timing or successful completion of a clinical trial.

Our product development costs will increase if we experience delays in clinical testing or in obtaining marketing approvals. We do not know whether any of our preclinical studies or clinical trials will begin as planned, will need to be restructured or will be completed on schedule, or at all. Significant preclinical or clinical trial delays also could shorten any periods during which we may have the exclusive right to commercialize our product candidates or allow our competitors to bring products to market before we do, potentially impairing our ability to successfully commercialize our product candidates and harming our business and results of operations.

We may not be able to initiate or continue clinical trials for our product candidates if we are unable to locate and enroll a sufficient number of eligible patients to participate in these trials as required by the FDA or similar regulatory authorities outside the United States. In addition, from time to time our competitors have ongoing clinical trials for product candidates that treat the same indications as our product candidates, and patients who would otherwise be eligible for our clinical trials may instead enroll in clinical trials of our competitors’ product candidates.

Opening trial sites outside the United States may involve additional regulatory, administrative and financial burdens, including compliance with foreign and local requirements relating to regulatory submission and clinical trial practices. Although the FDA may accept data from clinical trials conducted outside the United States, acceptance of these data is subject to certain conditions imposed by the FDA. For example, the clinical trial must be well designed and conducted and performed by qualified investigators in accordance with good clinical practices, or GCPs, and the FDA must be able to validate the data from the trial through an onsite inspection, if necessary. Generally, the patient population for any clinical trials conducted

In addition, the conduct of clinical trials outside the United States could have a significant impact on us. RisksAdditional risks inherent in conducting international clinical trials include:

There exist several designations that we may be unablecan apply for from the FDA and other regulators that would provide us with various combinations of the potential for expedited regulatory review, certain financial incentives as well as the potential for post-approval exclusivity for a period of time. These designations include but are not limited to maintain the benefits associated with orphan drug designation, including the potentialbreakthrough therapy designation, accelerated approval, fast track status and priority review for market exclusivity.

From time to time, we may publish interim, top-line or preliminary data from our clinical studies, which is based on a preliminary analysis of then-available data, and the results and related findings and conclusions are subject to change following a full analyses of all data related to the particular trial. For example, we and AskBio announced top-line data from the Phase 1 trial for SEL-399 in November 2021. We also make assumptions, estimations, calculations and conclusions as part of our analyses of data, and we may not have received or had the opportunity to fully and carefully evaluate all data. As a result, the top-line results that we report may differ from future results of the same studies, or different conclusions or considerations may qualify such results, once additional data have been received and fully evaluated. Preliminary or “top-line”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 we previously published. As a result, preliminary and top-line data should be viewed with caution until the final data are available. We may also disclose interim data from our clinical trials. Interim data from clinical trials that we may complete 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. Adverse differences betweenInterim, top-line or preliminary or interim data and

Further, others, including regulatory agencies, may not accept or agree with our assumptions, estimates, calculations, conclusions or analyses or may interpret or weigh the importance of data differently, which could impact the value of the particular program, the approvability or commercialization of the particular product candidate or product and our company in general. In addition, the information we choose to publicly disclose regarding a particular study or clinical trial is based on what is typically extensive information, and you or others may not agree with what we determine is the material or otherwise appropriate information to include in our disclosure. Any information we determine not to disclose may ultimately be deemed significant by you or others with respect to future decisions, conclusions, views, activities or otherwise regarding a particular product candidate or our business. If the interim,As a result, preliminary and top-line or preliminary data that we report differ from final results, or if others, including regulatory authorities, disagree with the conclusions reached, our ability to obtain approval for, and commercialize, product candidates may be harmed, which could seriously harm our business.

Gene therapy remains a novel technology. Public perception may be influenced by claims that gene therapy is unsafe, and gene therapy may not gain the acceptance of the public or the medical community. In particular, our success will depend upon physicians specializing in the treatment of those diseases that our product candidates target and prescribing treatments that involve the use of our product candidates in lieu of, or in addition to, existing treatments they are already familiar with and for which greater clinical data may be available. More restrictive government regulations or negative public opinion would have a negative effect on our business or financial condition and may delay or impair the development and commercialization of our product candidates or demand for any products we may develop. Our product candidates, including our products that utilize viral delivery systems, could produce adverse events. Adverse events in our clinical trials or following approval of any of our product candidates, even if not ultimately attributable to our product candidates, could result in increased governmental regulation, unfavorable public perception, potential regulatory delays in the testing or approval of our product candidates, stricter labeling requirements for those product candidates that are approved and a decrease in demand for any such product candidates.

Undesirable side effects caused by our product candidates could cause us or regulatory authorities to interrupt, delay or halt clinical trials, and could result in a more restrictive label or the delay or denial of regulatory approval by the FDA or other comparable foreign authorities.authorities and could result in decreased market acceptance of any of our product candidates, if approved. Further, therapies such as those we are developing involve unique side effects that could be exacerbated compared tomore significant than side effects from other types of therapies with singular components. Results of our clinical trials could reveal a high and unacceptable severity and prevalence of side effects. In such an event, our trials 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. For example, a patient in the Phase 1 trial of SEL-403 experienced a Grade 5 SAE (patient death) related to pneumonitis, which was deemed by the trial investigator to be probably related to ImmTOR and possibly related to the patient’s pleural mesothelioma condition, and in November 2018, the FDA placed the IND for SEL-403 on full clinical hold due to adverse events observed in the Phase 1 trial. Selecta has terminated the license of LMB-100 from NCI, effective April 9, 2019 and is no longer pursuing this product candidate.

Further, the SEL-212 multi-year clinical development program requiringof SEL-212 over many years has required multiple clinical trials and resulted in the use of different formulations of ImmTOR. While we do not believe that such differences in formulation will affect the safety or the efficacy of SEL-212, we cannot guarantee that any such formulation changes will not negatively impact the results of any clinical trials related to SEL-212, or result in a significant difference in the safety and efficacy of SEL-212.

The drug‑relateddrug-related side effects observed in our clinical trials could also affect patient enrollment in our clinical trials or the ability of any enrolled patients to complete such trials or result in potential product liability claims. Any of these occurrences may harm our business, financial condition and prospects significantly.

Any of these events could prevent us from achieving or maintaining market acceptance of a particular product candidate, if approved, and could significantly harm our business, results of operations and prospects.

We obtain the biologic pegadricase, a component of SEL‑212,SEL-212, primarily from 3SBio in China. Under our license agreement withthe 3SBio License, we have limited rights to manufacture pegadricase and while we have entered into a contract with a back-up supplier located outside of China, we expect to continue to rely on 3SBio as the primary supplier of pegadricase for the foreseeable future.

Any disruption in production or inability of 3SBio in China to produce adequate quantities of pegadricase to meet our needs whether as a result of a natural disaster, public health emergency, such as the novel coronavirus, failure to comply with regulatory requirements or other causes, could impair our ability to operate our business on a day‑to‑dayday-to-day basis and to continue our research and development of our future product candidates. Furthermore, since 3SBio is located in China, we are exposed to the possibility of product supply disruption and increased costs in the event of changes in the policies, laws, rules and regulations of the United States or Chinese governments, political unrest or unstable economic conditions in China. For example, trade tensions between the United States and China have been escalating in recent years. Most notably, several rounds of U.S. tariffs have been placed on Chinese goods being exported to the United States. Each of these U.S. tariff impositions against Chinese exports were followed by a round of retaliatory Chinese tariffs on U.S. exports to China. Pegadricase is subject to, and any other components we purchase from China may be subject to, these tariffs, which could increase our manufacturing costs and could make our products, if successfully developed and approved, less competitive than those of our competitors whose inputs are not subject to these tariffs.

Any of these matters could materially and adversely affect our business and results of operations. Any issues related to the manufacturing lots or similar action regarding pegadricase used in preclinical studies or clinical trials could delay the studies or trials or detract from the integrity of the trial data and its potential use in future regulatory filings. In addition, manufacturing interruptions or failure to comply or maintain compliance with regulatory requirements by 3SBio could significantly delay our clinical development of potential products and reduce third‑partythird-party or clinical researcher interest and support of our proposed trials. These interruptions or failures could also impede commercialization of our future product candidates and impair our competitive position. Further, we may be exposed to fluctuations in the value of the local currency in China. Future appreciation of the local currency could increase our costs. In addition, labor costs could continue to rise asThese factors and increasing wage rates increase due to increased demand for skilled laborers and the declining availability of skilled labor declines in China.China could cause our labor costs to rise.

We may be unable to establish any agreements with third‑partythird-party manufacturers on acceptable terms or at all. Evenall, and even if we are able to establish agreements with third‑party manufacturers, reliancedo rely on third‑partythird-party manufacturers entails additional risks, including the:

Additionally, if our contract manufacturers cannot successfully manufacture material that conforms to our specifications and the strict regulatory requirements of the FDA or others, they will not be able to secure and/or maintain regulatory approval for their manufacturing facilities. In addition, we have no control over the ability of our contract manufacturers or suppliers to maintain adequate quality control, quality assurance and qualified personnel. If the FDA or a comparable foreign regulatory authority does not approve these facilities for the manufacture of our product candidates or if it withdraws any such approval in the future, we may need to find alternative manufacturing facilities, which would significantly impact our ability to develop, obtain regulatory approval for or market our product candidates, if approved. Our failure, or the failure of our third‑partythird-party manufacturers, to comply with applicable regulations could result in sanctions being imposed on us, including clinical holds, fines, injunctions, civil penalties, delays, suspension or withdrawal of approvals, license revocations, seizures or recalls of product candidates or products, operating restrictions and criminal prosecutions, any of which could significantly and adversely affect supplies of our products. In addition, there are a limited number of manufacturers that operate under cGMP regulations that might be capable of manufacturing our products. Therefore, our product candidates and any future products that we may develop may compete with other products for access to manufacturing facilities. Any failure to gain access to these limited manufacturing facilities could severely impact the clinical development, marketing approval and commercialization of our product candidates.

Any performance failure on the part of our existing or future manufacturers could delay clinical development or marketing approval. We do not currently have arrangements in place for redundant supply or a second source for required raw materials used in the manufacture of our product candidates or for the manufacture of finished product. Moreover, we often rely on one CMO to produce multiple product components. For instance, one of our CMOs produces several polymers used in our ImmTOR platform. If our current CMOs cannot perform as agreed, we may be required to replace such manufacturers and we may be unable to replace them on a timely basis or at all. Our current and expected future dependence upon others for the manufacture of our product candidates or products could delay, prevent or impair our development and commercialization efforts.

We have entered into collaborations with other parties, including pharmaceutical and biotechnology companies and universities, to develop products based on our ImmTOR platform, and such collaborations and licensing arrangements currently represent a significant portion of our product pipeline and are expected to represent a larger portion of our pipeline in the future. Certain of our collaborations have provided us with important funding for some of our development programs and we expect to receive additional funding under collaborations in the future although not all of our collaborations may result in funding to the Company,us, and certain collaborations, licenses and agreements may result in increased expenditures by the Company.us. Our existing collaborations, and any future collaborations, we enter into, may pose a number of risks, including the following:

We are actively exploring licenses and other strategic collaborations with additional pharmaceutical and biotechnology companies for development and potential commercialization of therapeutic products. However, we face significant competition in seeking appropriate collaborators. If we are unable to reach agreements with suitable collaborators on a timely basis, on acceptable terms, or at all, we may not be able to access specific antigens that would be suitable to development with our technology, have to curtail the development of a product candidate, reduce or delay its development program or one or more of our other development programs, delay its potential commercialization or reduce the scope of any sales or marketing activities, or increase our expenditures and undertake development or commercialization activities at our own expense. If we elect to fund and undertake development or commercialization activities on our own, we may need to obtain additional expertise and additional capital, which may not be available to us on acceptable terms or at all. If we fail to enter into collaborations and do not have sufficient funds or expertise to undertake the necessary development and commercialization activities, we may not be able to further develop our product candidates or bring them to market or continue to develop our programs, and our business may be materially and adversely affected.

We rely, and expect to continue to rely, on third parties, such as CROs, clinical data management organizations, medical institutions and clinical investigators, to conduct and manage our clinical trials, including our Phase 2 andongoing Phase 3 DISSOLVE clinical program for SEL-212, consisting of the DISSOLVE I and DISSOLVE II trials, which we have agreed to continue to run on behalf of SEL‑212Sobi, and for our other product candidates. We also expect to rely on other third parties to store and distribute drug supplies for our clinical trials.

Furthermore, these third parties may also have relationships with other entities, some of which may be our competitors. If these third parties do not successfully carry out their contractual duties, do not comply with confidentiality obligations, do not meet expected deadlines, experience work stoppages, terminate their agreements with us or need to be replaced, or do not conduct our clinical trials in accordance with regulatory requirements or our stated protocols, we may need to enter into new arrangements with alternative third parties, which could be difficult, costly or impossible, and our clinical trials may be extended, delayed or terminated, or may need to be repeated. If any of the foregoing occur, we may not be able to obtain, or may be delayed in obtaining, marketing approvals for our product candidates or in commercializing our product candidates.

We have a pilot manufacturing facility at our Watertown, Massachusetts location where we conduct process development, scale‑upscale-up activities and the manufacture of ImmTOR product candidates for preclinical use. We rely on our scaled equipment installed at our CMOs for the manufacture of the clinical supply of all of our product candidates. If our facility, or our CMOs’ facilities, were damaged or destroyed, or otherwise subject to disruption, it would require substantial lead‑time to replace our manufacturing capabilities. In such event, we would be forced to identify and rely entirely on alternative third‑party contract manufacturers for an indefinite period of time. Any disruptions or delays at our facility or its failure to meet regulatory compliance would impair our ability to develop and commercialize our product candidates, which would adversely affect our business and results of operations.

If any of our product candidates receives marketing approval, it may nonetheless fail to gain sufficient market acceptance by physicians, patients, third‑partythird-party payors and others in the medical community. If our product candidates do not achieve an adequate level of acceptance, we may not generate significant product revenues and we may not become profitable. For example, even if the statistical results from our Phase 2 head-to-head (COMPARE) trial vs. KRYSTEXXA favor SEL-212 and SEL-212 receives marketing approval, the drug may fail to gain market acceptance from physicians, patients, third-party payors and others in the medical community who may continue to favor KRYSTEXXA. The degree of market acceptance of our product candidates, if any,approved for commercial sale, will depend on a number ofseveral factors, including:

We do not have a sales or marketing infrastructure and have no experience in the sale, marketing or distribution of pharmaceutical products. To achieve commercial success for any product candidate for which we obtain marketing approval, we will need to establish a sales and marketing organization or make arrangements with third parties to perform sales and marketing functions and we may not be successful in doing so.

The development and commercialization of new drug and biologic products and technologies is highly competitive and is characterized by rapid and substantial technological development and product innovations. We are aware that pharmaceutical and biotechnology companies, including Horizon Pharma plc, offer or are pursuing the development of pharmaceutical products or technologies that may address one or more indications that our product candidates target, as well as smaller, early-stage companies, that offer or are pursuing the development of pharmaceutical products or technologies that may address one or more indications that our product candidates target. We face competition with respect to our current product candidates, and will face competition with respect to any product candidates that we may seek to develop or commercialize in the future, from major pharmaceutical companies, specialty pharmaceutical companies and biotechnology companies worldwide.

Many of the companies against which we are competing or against which we may compete in the future have significantly greater financial resources, established presence in the market and expertise in research and development, manufacturing, preclinical testing, conducting clinical trials, obtaining regulatory approvals and reimbursement for product candidates and in marketing approved products than we do. Mergers and acquisitions in the pharmaceutical and biotechnology industries may result in even more resources being concentrated among a smaller number of our competitors.

These third parties compete with us in recruiting and retaining qualified scientific, sales and marketing and management personnel, establishing clinical trial sites and patient registration for clinical trials, as well as in acquiring technologies complementary to, or necessary for, our programs.

Our commercial opportunity could be reduced or eliminated if our competitors develop and commercialize products that are more effective, have fewer or less severe side effects, are more convenient or are less expensive than any products that we may develop. Our competitors also may obtain FDA or other regulatory approval for their products more rapidly than we may obtain approval for ours, which could result in our competitors establishing a strong market position before we are able to enter the market, especially for any competitor developing a competing immunomodulating therapeutic that will likely share our same regulatory approval requirements. In addition, our ability to compete may be affected in many cases by insurers or other third‑partythird-party payors seeking to encourage the use of generic or biosimilar products.

The Biologics Price Competition and Innovation Act of 2009 (BPCIA)BPCIA was enacted as part of the Affordable Care Act to establish an abbreviated pathway for the approval of biosimilar and interchangeable biological products. The regulatory pathway establishes legal authority for the FDA to review and approve biosimilar biologics, including the possible designation of a biosimilar as “interchangeable” based on its similarity to an approved biologic. Under the BPCIA, an application for a biosimilar product cannot be approved by the FDA until 12 years after the reference product was approved under a BLA. The law is complex and is still being interpreted and implemented by the FDA. AsFDA, and as a result, its ultimate impact, implementation, and meaning are subject to uncertainty. While it is uncertain when such processes intended to implement the BPCIA may be fully adopted by the FDA,However, any such processes could have a material adverse effect on the future commercial prospects for our biological products.

We believe that any product candidate approved in the United States as a biological product under a BLA should qualify for the 12-year period of exclusivity. However, there is a risk that this exclusivity could be shortened due to congressionalCongressional action or otherwise, or that the FDA will not consider the subject product candidates to be reference products for competing products, potentially creating the opportunity for generic competition sooner than anticipated. Moreover, the extent to which a biosimilar, once approved, will be substituted for any one of the reference products in a way that is similar to traditional generic substitution for non-biological products is not yet clear, and will depend on a number of marketplace and regulatory factors that are still developing.

Significant uncertainty exists as to the coverage and reimbursement status of any product candidates for which we obtain regulatory approval, especially novel products like our gene therapy product candidates, and may be particularly difficult because of the higher prices associated with gene therapy product candidates. Our ability to commercialize any product candidates successfully will depend, in part, on the extent to which coverage and adequate reimbursement for these products and related treatments will be available from government health administration authorities, private health insurers and other organizations. Government authorities and third‑partythird-party payors, such as private health insurers and health maintenance organizations, decide which medications they will pay for and establish reimbursement levels.

Obtaining and maintaining adequate reimbursement for our products may be difficult. We cannot be certain if and when we will obtain an adequate level of reimbursement for our products by third‑partythird-party payors. Even if we do obtain adequate levels of reimbursement, third‑partythird-party payors, such as government or private healthcare insurers, carefully review and increasingly question the coverage of, and challenge the prices charged for, products. Government authorities and third‑partythird-party payors have attempted to control costs by limiting coverage and the amount of reimbursement for particular medications. Increasingly, third‑partyThird-party payors are requiringoften require that pharmaceutical companies provide them with predetermined discounts from list prices and are challenging the prices charged for products. We may also be required to conduct expensive pharmacoeconomic studies to justify coverage and reimbursement or the level of reimbursement relative to other therapies. Some third-party payors may require pre-approval of coverage for new and innovative therapies, such as our product candidates, before they will provide reimbursement. If coverage and reimbursement are not available or reimbursement is available only to limited levels, we may not be able to successfully commercialize any product candidate for which we obtain marketing approval.

There may be significant delays in obtaining reimbursement for newly approved products, and coverage may be more limited than the purposes for which the product is approved by the FDA or similar regulatory authorities outside of the United States. Moreover, eligibility for reimbursement does not imply that a product will be paid for in all cases or at a rate that covers our costs, including research, development, manufacture, sale and distribution. Interim reimbursement levels for new products,

Moreover, there has recently beenis heightened governmental scrutiny over the manner in which manufacturers set prices for their marketed products, which has resulted in several Congressional inquiries and proposed bills designed to, among other things, bring more transparency to product pricing, review the relationship between pricing and manufacturer patient programs, and reform government program reimbursement methodologies for drug products. There can be no assurance that our product candidates, if approved for sale in the United States or in other countries, will not be subject to heightened governmental scrutiny, unfavorable regulatory inquiry or action, or congressionalCongressional inquiry.

We face an inherent risk of product liability exposure related to the testing of our product candidates in clinical trials and will face an even greater risk if we commercially sell any products that we may develop. If we cannot successfully defend ourselves against claims that our product candidates or products caused injuries, we will incur substantial liabilities. Regardless of merit or eventual outcome, liability claims may result in:

We maintain general liability, product liability and umbrella liability insurance. Our existing insurance coverage may not fully cover potential liabilities that we may incur. We may need to increase our insurance coverage as we expand our clinical trials or if we commence commercialization of our product candidates. Insurance coverage is increasingly expensive. We may not be able to maintain insurance coverage at a reasonable cost or in an amount adequate to satisfy any liability that may arise. A successful product liability claim or series of claims brought against us could cause our share price to decline and, if judgments exceed our insurance coverage, could adversely affect our results of operations and business, including preventing or limiting the commercialization of any product candidates we develop.

Arrangements with physicians, others who may be in a position to generate business for us, and customers may expose us to broadly applicable fraud and abuse and other healthcare laws and regulations that constrain the business or financial arrangements and relationships through which we market, sell and distribute any products for which we obtain marketing approval. Restrictions under applicable federal and state healthcare laws and regulations include the following:

Efforts to ensure that our business arrangements with third parties comply with applicable healthcare laws and regulations will involve substantial costs. It is possible that governmental authorities will conclude that our business practices, including our relationships with physicians and other healthcare providers, some of whom may recommend, purchase and/or prescribe our product candidates, if approved, may not comply with current or future statutes, regulations or case law involving applicable fraud and abuse or other healthcare laws and regulations. If our operations are found to be in violation of any of these laws or

In the United States and some foreign jurisdictions, there have been a number of legislative and regulatory changes and proposed changes regarding the healthcare system that could prevent or delay marketing approval of our product candidates, restrict or regulate post‑approvalpost-approval activities and affect our ability to profitably sell any product candidates for which we obtain marketing approval.

For example, the Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act, or collectively the ACA, is a sweeping law intended to broaden access to health insurance, reduce or constrain the growth of healthcare spending, enhance remedies against fraud and abuse, add new transparency requirements for the healthcare and health insurance industries, impose new taxes and fees on the health industry and impose additional health policy reforms.

We expect that the ACA, as well as other healthcare reform measures that may be adopted in the future, may result in additional reductions in Medicare and other healthcare funding, more rigorous coverage criteria, new payment methodologies and additional downward pressure on the price that we receive for any approved product. Any reduction in reimbursement from Medicare or other government programs may result in a similar reduction in payments from private payors. The implementation of cost containment measures or other healthcare reforms may prevent us from being able to generate revenue, attain profitability or commercialize our products.

The ability of the FDA to review and or approve new products can be affected by a variety of factors, including government budget and funding levels, statutory, regulatory, and policy changes, the FDA’s ability to hire and retain key personnel and accept the payment of user fees, and statutory, regulatory, and policy changes.other events that may otherwise affect the FDA’s ability to perform routine functions. Average review times at the agency have fluctuated in recent years as a result. In addition, government funding of other government agencies that fund research and development activities is subject to the political process, which is inherently fluid and unpredictable.

We are subject to export control and import laws and regulations, including the U.S. Export Administration Regulations administered by the U.S. Commerce Department’s Bureau of Industry and Security, U.S. Customscustoms regulations, various economic and trade sanctions regulations including those administered or enforced by relevant government authorities, such as by the U.S. Treasury Department’s Office of Foreign Assets Control or the U.S. Department of State, the U.S. Foreign Corrupt Practices Act of 1977, as amended, or FCPA, the U.S. domestic bribery statute contained in 18 U.S.C. § 201, the U.S. Travel Act, the USA PATRIOT Act, and other state and national anti‑briberyanti-bribery and anti‑moneyanti-money laundering laws in the countries in which

We and our contract manufacturers and other third parties with whom we do business are subject to numerous environmental, health and safety laws and regulations, including those governing laboratory procedures and the handling, use, storage, treatment and disposal of hazardous materials and wastes. Our operations involve the use of hazardous and flammable materials, including biological materials and chemicals. Our operations also produce hazardous waste products. We generally contract with third parties for the disposal of these materials and wastes. We cannot eliminate the risk of contamination or injury from these materials. In the event of contamination or injury resulting from our use of hazardous materials, we could be held liable for any resulting damages, and any liability could exceed our resources. We also could incur significant costs associated with civil or criminal fines and penalties for failure to comply with such laws and regulations.

Although we maintain workers’ compensation insurance to cover us for costs and expenses we may incur due to injuries to our employees resulting from the use of hazardous materials, this insurance may not provide adequate coverage against potential liabilities. We do not maintain insurance for environmental liability or toxic tort claims that may be asserted against us in connection with our storage or disposal of biological, hazardous or radioactive materials.

In addition, we may incur substantial costs in order to comply with current or future environmental, health and safety laws and regulations. These current or future laws and regulations may impair our research, development or production efforts. The failure to comply with these laws and regulations also may result in substantial fines, penalties or other sanctions.

Our success depends in large part on our ability to obtain and maintain patent and other intellectual property protection in the United States and other countries with respect to our proprietary technology and products. We seek to protect our proprietary position by filing patent applications in the United States and abroad related to our novel technologies and product candidates. We also rely on trade secrets to protect aspects of our business that are not amenable to, or that we do not consider appropriate for, patent protection.

The patent prosecution process is expensive and time‑consuming,time-consuming, and we may not be able to file and prosecute all necessary or desirable patent applications at a reasonable cost, in a timely manner or in all jurisdictions. As we reach the statutory deadlines for deciding whether and where to initiate prosecution in specific foreign jurisdictions by filing national stage applications based on our Patent Cooperation Treaty, or PCT, applications, we will have to decide whether and where to pursue patent

In some circumstances, we may not have the right to control the preparation, filing and prosecution of patent applications, or to maintain the patents covering technology that we license from third parties. We may also require the cooperation of our licensors to enforce any licensed patent rights, and such cooperation may not be provided. Therefore, these patents and applications may not be prosecuted and enforced in a manner consistent with the best interests of our business. Moreover, we have obligations under our licenses, and any failure to satisfy those obligations could give our licensor the right to terminate the license. Termination of a necessary license could have a material adverse impact on our business.

We cannot provide any assurances that the issued patents we currently own, or any future patents, include claims with a scope sufficient to protect our product candidates or otherwise provide any competitive advantage. Further, it is possible that a patent claim may provide coverage for some but not all parts of a product candidate or third‑partythird-party product. These and other factors may provide opportunities for our competitors to design around our patents.

Moreover, other parties may have developed technologies that may be related or competitive to our approach, and may have filed or may file patent applications, and may have received or may receive patents that may overlap or conflict with our patent applications, either by claiming similar methods or by claiming subject matter that could dominate our patent position. In addition, it may be some time before we understand how the patent office reacts to our patent claims and whether they identify prior art of relevance that we have not already considered.

Publications of discoveries in the scientific literature often lag behind the actual discoveries, and patent applications in the United States and other jurisdictions are typically not published until 18 months after filing, or in some cases not at all. Therefore, we cannot know with certainty whether we were the first to make the inventions claimed in any owned patents or pending patent applications, or that we were the first to file for patent protection of such inventions, nor can we know whether those from whom we may license patents were the first to make the inventions claimed or were the first to file. For these and other reasons, the issuance, scope, validity, enforceability and commercial value of our patent rights are subject to a level of uncertainty. Our pending and future patent applications may not result in patents being issued that protect our technology or products, in whole or in part, or which effectively prevent others from commercializing competitive technologies and products. Changes in either the patent laws or interpretation of the patent laws in the United States and other countries may diminish the value of our patents or narrow the scope of our patent protection.

We may be subject to a third‑partythird-party preissuance submission of prior art to the U.S. Patent and Trademark Office, or USPTO, or become involved in opposition, derivation, reexamination, inter partes review, post‑grantpost-grant review or interference proceedings challenging our patent rights or the patent rights of others. An adverse determination in any such submission, proceeding or litigation could reduce the scope of, or invalidate, our patent rights, allow third parties to commercialize our technology or products and compete directly with us, without payment to us, or result in our inability to manufacture or commercialize product candidates without infringing third‑partythird-party patent rights. In addition, if the breadth or strength of protection provided by our patents and patent applications is threatened, it could dissuade companies from collaborating with us to license, develop or commercialize current or future product candidates. Furthermore, an adverse decision in an interference proceeding can result in a third party receiving the patent right sought by us, which in turn could affect our ability to develop, market or otherwise commercialize our product candidates. The issuance, scope, validity, enforceability and commercial value of our patents are subject to a level of uncertainty.

The patent position of biotechnology and pharmaceutical companies generally is highly uncertain, involves complex legal and factual questions and has in recent years been the subject of much litigation. Due to legal standards relating to patentability, validity, enforceability and claim scope of patents covering biotechnological and pharmaceutical inventions, our ability to obtain, maintain and enforce patents is uncertain and involves complex legal and factual questions. Even if issued, a patent’s validity, inventorship, ownership or enforceability is not conclusive. Accordingly, rights under any existing patent or any patents we might obtain or license may not cover our product candidates, or may not provide us with sufficient protection for our product candidates to afford a commercial advantage against competitive products or processes, including those from branded and generic pharmaceutical companies.

Any litigation to enforce or defend our patent rights, even if we were to prevail, could be costly and time‑consumingtime-consuming and would divert the attention of our management and key personnel from our business operations. We may not prevail in any lawsuits that we initiate and the damages or other remedies awarded if we were to prevail may not be commercially meaningful. Even if we are successful, domestic or foreign litigation, or USPTO or foreign patent office proceedings, may result in substantial costs and distraction to our management. We may not be able, alone or with our licensors or potential collaborators, to prevent misappropriation of our proprietary rights, particularly in countries where the laws may not protect such rights as fully as in the United States. Furthermore, because of the substantial amount of discovery required in connection with

In addition to seeking patents for some of our technology and product candidates, we also rely on trade secrets, including unpatented know‑how,know-how, technology and other proprietary information, to maintain our competitive position. We seek to protect these trade secrets, in part, by entering into non‑disclosurenon-disclosure and confidentiality agreements with parties who have access to them, such as our employees, corporate collaborators, outside scientific collaborators, contract manufacturers, consultants, advisors and other third parties. We also seek to enter into confidentiality and invention or patent assignment agreements with our employees, advisors and consultants. Despite these efforts, any of these parties may breach the agreements and disclose our proprietary information, including our trade secrets, and we may not be able to obtain adequate remedies for such breaches. Our trade secrets may also be obtained by third parties by other means, such as breaches of our physical or computer security systems. Enforcing a claim that a party illegally disclosed or misappropriated a trade secret is difficult, expensive and time‑consuming,time-consuming, and the outcome is unpredictable. In addition, some courts inside and outside the United States are less willing or unwilling to protect trade secrets. Moreover, if any of our trade secrets were to be lawfully obtained or independently developed by a competitor, we would have no right to prevent them, or those to whom they communicate it, from using that technology or information to compete with us. If any of our trade secrets were to be disclosed to, or independently developed by, a competitor, our competitive position would be harmed.

As is the case with other biotechnology companies, our success is heavily dependent on intellectual property, particularly patents. Obtaining and enforcing patents in the biotechnology industry involves both technological and legal complexity, and is therefore costly, time‑consumingtime-consuming and inherently uncertain. In addition, recent patent reform legislation could further increase the uncertainties and costs surrounding the prosecution of our patent applications and the enforcement or defense of our issued patents. On September 16, 2011, the Leahy‑SmithThe Leahy-Smith Act America Invents Act, or the Leahy‑SmithLeahy-Smith Act, was signed into law. The Leahy‑Smith Act includes a number of significant changes to U.S. patent law. These includeincluded provisions that affect the way patent applications are prosecuted and may also affect patent litigation. The USPTO recently developed new regulations and procedures to govern administration of the Leahy‑Smith Act, and many of the substantive changes to patent law associated with the Leahy‑Smith Act, in particular the first to file provisions, became effective on March 16, 2013.litigation, including first-to-file provisions. A third party that files a patent application in the USPTO after that date but before us could therefore be awarded a patent covering an invention of ours even if we had made the invention before it was made by the third party. This requires us to be cognizant of the time from invention to filing of a patent application. Thus, for our U.S. patent applications containing a priority claim after March 16, 2013, the date such provisions became effective, there is a greater level of uncertainty in the patent law. Moreover, some of the patent applications in our portfolio will be subject to examination under the pre‑Leahy‑Smithpre-Leahy-Smith Act law and regulations, while other patents applications in our portfolio will

In addition, the Leahy‑SmithLeahy-Smith Act limits where a patentee may file a patent infringement suit and provides opportunities for third parties to challenge any issued patent in the USPTO. These provisions apply to all of our U.S. patents, even those issued before March 16, 2013. Because of a lower evidentiary standard in USPTO proceedings compared to the evidentiary standard in U.S. federal court necessary to invalidate a patent claim, a third party could potentially provide evidence in a USPTO proceeding sufficient for the USPTO to hold a claim invalid even though the same evidence would be insufficient to invalidate the claim if first presented in a federal court action.

Accordingly, a third party may attempt to use the USPTO procedures to invalidate our patent claims because it may be easier for them to do so relative to challenging the patent in a federal court action. It is not clear what, if any, impact the Leahy‑SmithLeahy-Smith Act will have on the operation of our business. However, the Leahy‑SmithLeahy-Smith Act and its implementation could increase the uncertainties and costs surrounding the prosecution of our patent applications and the enforcement or defense of our issued patents, all of which could have a material adverse effect on our business and financial condition.

In addition, recent U.S. Supreme Court rulings have narrowed the scope of patent protection available in certain circumstances and weakened the rights of patent owners in certain situations. From time to time, the U.S. Supreme Court, other federal courts, the U.S. Congress or the USPTO may change the standards of patentability, and any such changes could have a negative impact on our business.

Depending on these and other decisions by the U.S. Congress, the federal courts and the USPTO, the laws and regulations governing patents could change or be interpreted in unpredictable ways that would weaken our ability to obtain new patents or to enforce any patents that may issue to us in the future. In addition, these events may adversely affect our ability to defend any patents that may issue in procedures in the USPTO or in courts.

Our commercial success depends upon our ability, and the ability of our collaborators, to develop, manufacture, market and sell our product candidates and use our proprietary technologies without infringing the proprietary rights of third parties. There is considerable intellectual property litigation in the biotechnology and pharmaceutical industries. While no such litigation has been brought against us and we have not been held by any court to have infringed a third party’s intellectual property rights, we cannot guarantee that our technology, product candidates or use of our product candidates do not infringe third‑partythird-party patents.

We are aware of numerous patents and pending applications owned by third parties, and we monitor patents and patent applications in the fields in which we are developing product candidates, both in the United States and elsewhere. However, we may have failed to identify relevant third‑partythird-party patents or applications. For example, applications filed before November 29, 2000 and certain applications filed after that date that will not be filed outside the United States remain confidential until patents issue. Moreover, it is difficult for industry participants, including us, to identify all third‑partythird-party patent rights that may be relevant to our product candidates and technologies because patent searching is imperfect due to differences in terminology among patents, incomplete databases and the difficulty in assessing the meaning of patent claims. We may fail to identify relevant patents or patent applications or may identify pending patent applications of potential interest but incorrectly predict the likelihood that such patent applications may issue with claims of relevance to our technology. In addition, we may be unaware of one or more issued patents that would be infringed by the manufacture, sale or use of a current or future product candidate, or we may incorrectly conclude that a third‑partythird-party patent is invalid, unenforceable or not infringed by our activities. Additionally, pending patent applications that have been published can, subject to certain limitations, be later amended in a manner that could cover our technologies, our product candidates or the use of our product candidates.

The biotechnology and pharmaceutical industries are characterized by extensive litigation regarding patents and other intellectual property rights. Other parties may allege that our product candidates or the use of our technologies infringes patent claims or other intellectual property rights held by them or that we are employing their proprietary technology without authorization. We may become party to, or threatened with, future adversarial proceedings or litigation regarding intellectual property rights with respect to our product candidates and technology, including interference or derivation proceedings before the USPTO and similar bodies in other countries. Third parties may assert infringement claims against us based on existing intellectual property rights and intellectual property rights that may be granted in the future.

Patent and other types of intellectual property litigation can involve complex factual and legal questions, and their outcome is uncertain. If we are found, or believe there is a risk we may be found, to infringe a third party’s intellectual property rights, we could be required or may choose to obtain a license from such third party to continue developing and marketing our product candidates and technology. However, we may not be able to obtain any such license on commercially reasonable terms or at all. Even if we were able to obtain a license, it could be non‑exclusive,non-exclusive, thereby giving our competitors access to the same technologies licensed to us. We could be forced, including by court order, to cease commercializing the infringing technology

Even if we are successful in such proceedings, we may incur substantial costs and divert management time and attention in pursuing these proceedings, which could have a material adverse effect on us. Patent litigation is costly and time‑consuming.time-consuming. We may not have sufficient resources to bring these actions to a successful conclusion. There could be public announcements of the results of hearings, motions or other interim proceedings or developments and if securities analysts or investors perceive these results to be negative, it could have a substantial adverse effect on the price of our common stock.

Any of these risks coming to fruition could have a material adverse impact on our business.

Competitors may infringe our intellectual property, including our patents or the patents of our licensors. As a result, we may be required to file infringement claims to stop third‑partythird-party infringement or unauthorized use. This can be expensive, particularly for a company of our size, and time‑consuming.time-consuming. If we initiated legal proceedings against a third party to enforce a patent, if and when issued, covering one of our product candidates, the defendant could counterclaim that the patent covering our product candidate is invalid and/or unenforceable. In patent litigation in the United States, defendant counterclaims alleging invalidity and/or unenforceability are commonplace. Grounds for a validity challenge include alleged failures to meet any of several statutory requirements, including lack of novelty, obviousness or non‑enablement,non-enablement, or failure to claim patent‑eligiblepatent-eligible subject matter. Grounds for unenforceability assertions include allegations that someone connected with the prosecution of the patent withheld relevant information from the USPTO, or made a misleading statement, during prosecution. Third parties may

Patents have a limited lifespan. In the United States, the natural expiration of a patent is generally 20 years after its first effective non-provisional filing date. Although various extensions may be available, the life of a patent, and the protection it affords, is limited. Even if patents covering our product candidates, proprietary technologies and their uses are obtained, once the patent life has expired, we may be open to competition. In addition, although upon issuance in the United States a patent’s life can be increased based on certain delays caused by the USPTO, this increase can be reduced or eliminated based on certain delays caused by the patent applicant during patent prosecution. Given the amount of time required for the development, testing and regulatory review of new product candidates, patents protecting such candidates might expire before or shortly after such candidates are commercialized. If we do not have sufficient patent life to protect our product candidates, proprietary technologies and their uses, our business and results of operations will be adversely affected.

Periodic maintenance fees on any issued patent are due to be paid to the USPTO and foreign patent agencies in several stages over the lifetime of the patent and, in some jurisdictions, during the pendency of a patent application. The USPTO and various foreign governmental patent agencies require compliance with a number of procedural, documentary, fee payment and other similar provisions during the patent application process. While an inadvertent lapse can in many cases be cured by payment of a late fee or by other means in accordance with the applicable rules, there are situations in which noncompliance can result in abandonment or lapse of the patent or patent application, resulting in partial or complete loss of patent rights in the relevant jurisdiction. Noncompliance events that could result in abandonment or lapse of a patent or patent application include, but are not limited to, failure to respond to official actions within prescribed time limits, non‑paymentnon-payment of fees and failure to properly

We are party to multiple license agreements that impose, and we may enter into additional licensing and funding arrangements with third parties that may impose, diligence, development and commercialization timelines, milestone payment, royalty, insurance and other obligations on us. Under our existing licensing agreements, we are obligated to pay royalties on net product sales of product candidates or related technologies to the extent they are covered by the agreement. Our results of operations will be affected by the level of royalty payments that we are required to pay to third parties. We cannot precisely predict the amount, if any, of royalties that we will be required to pay to third parties in the future. Any disagreements with the counterparty over the amount of royalties owed could lead to litigation, which is costly. In addition, if we fail to comply with our obligations under current or future license agreements, our counterparties may have the right to terminate these agreements, in which event we might not be able to develop, manufacture or market any product candidate that is covered by these agreements, or may face other penalties under the agreements. Such an occurrence could materially adversely affect the value of product candidates being developed using rights licensed to us under any such agreement. Termination of these agreements or reduction or elimination of our rights under these agreements may result in our having to negotiate new or reinstated agreements with less favorable terms, or cause us to lose our rights under these agreements, including our rights to important intellectual property or technology. Furthermore, our counterparties may allege that we are operating outside the scope of the licenses granted and terminate our license or otherwise require us to alter development, manufacturing or marketing activities.

We currently have rights to certain intellectual property, through licenses from third parties and under patents and patent applications that we own, to develop our product candidates. Because we may find that our programs require the use of proprietary rights held by third parties, the growth of our business may depend in part on our ability to acquire, in‑licensein-license or use these proprietary rights. We may be unable to acquire or in‑licensein-license compositions, methods of use, processes or other third‑party third-party

Many of our employees were previously employed at universities or other biotechnology or pharmaceutical companies, including our competitors or potential competitors. We may also engage advisors and consultants who are concurrently employed at universities or other organizations or who perform services for other entities. Although we try to ensure that our employees, advisors and consultants do not use the proprietary information or know‑howknow-how of others in their work for us, we may be subject to claims that we or our employees, advisors or consultants have used or disclosed intellectual property, including trade secrets or other proprietary information, of any such party’s former or current employer or in violation of an agreement with another party. Although we have no knowledge of any such claims being alleged to date, if such claims were to arise, litigation may be necessary to defend against any such claims.

If we fail in prosecuting or defending any such claims, in addition to paying monetary damages, we may lose valuable intellectual property rights or personnel. Even if we are successful in prosecuting or defending against such claims, litigation could result in substantial costs and be a distraction to management.

Filing, prosecuting and defending patents on product candidates in all countries and jurisdictions throughout the world would be prohibitively expensive, and our intellectual property rights in some countries outside the United States could be less extensive than in the United States, assuming that rights are obtained in the United States and assuming that rights are pursued outside the United States. In this regard, in addition to the United States, we also seek to protect our intellectual property rights in other countries. The statutory deadlines for pursuing patent protection in individual foreign jurisdictions are based on the priority date of each of our patent applications. For all of the patent families in our portfolio, including the families that may provide coverage for our lead product candidate, the relevant statutory deadlines have not yet expired. Therefore, for each of the patent families that we believe provide coverage for our lead product candidate, we will need to decide whether and where to pursue additional protection outside the United States. In addition, the laws of some foreign countries, do not protect intellectual property rights to the same extent as federal and state laws in the United States. Consequently, for our existing patent rights outside the United States and any foreign patent rights we may decide to pursue in the future, we may not be able to obtain relevant claims and/or we may not be able to prevent third parties from practicing our inventions in all countries outside the United States, or from selling or importing products made using our inventions in and into the United States or other jurisdictions.

Competitors may use our technologies in jurisdictions where we do not pursue and obtain patent protection to develop their own products and further, may export otherwise infringing products to territories where we have patent protection, but enforcement is not as strong as in the United States. These products may compete with our product candidates and our patents or other intellectual property rights may not be effective or sufficient to prevent them from competing. Even if we pursue and obtain issued patents in particular jurisdictions, our patent claims or other intellectual property rights may not be effective or sufficient to prevent third parties from so competing.

Depending upon the timing, duration and specifics of FDA regulatory approval for our product candidates, one or more of our U.S. patents may be eligible for limited patent term restoration under the Hatch‑WaxmanHatch-Waxman Act. The Hatch‑WaxmanHatch-Waxman Act permits a patent restoration term of up to five years as compensation for patent term lost during product development and the FDA regulatory review process. Patent term restorations, however, are limited to a maximum of five years and cannot extend the remaining term of a patent beyond a total of 14 years from the date of product approval by the FDA.

The application for patent term extension is subject to approval by the USPTO, in conjunction with the FDA. It takes at least six months to obtain approval of the application for patent term extension. We may not be granted an extension because of, for example, failing to apply within applicable deadlines, failing to apply prior to expiration of relevant patents or otherwise failing to satisfy applicable requirements. Moreover, the applicable time period or the scope of patent protection afforded could be less than we request. If we are unable to obtain patent term extension or restoration or the term of any such extension is less than we request, the period during which we will have the right to exclusively market our product will be shortened, our competitors may obtain earlier approval of competing products and our ability to generate revenues could be materially adversely affected.

We are highly dependent on Carsten Brunn, Ph.D., our President and Chief Executive Officer, as well as the other principal members of our management, scientific and clinical team. Although we have entered into employment agreements or offer letters with Dr. Brunn and other executive officers, each of them may terminate their employment with us at any time. We do not maintain “key person” insurance for any of our executives or other employees.

Recruiting and retaining qualified scientific, clinical, manufacturing, technology and sales and marketing personnel will also be critical to our success. The loss of the services of our executive officers or other key employees could impede the achievement of our research, development and commercialization objectives and seriously harm our ability to successfully implement our business strategy. Furthermore, replacing executive officers and key employees may be difficult and may take an extended period of time because of the limited number of individuals in our industry with the breadth of skills and experience required to successfully develop, gain regulatory approval of and commercialize product candidates. Competition to hire from this limited pool is intense, and we may be unable to hire, train, retain or motivate these key personnel on acceptable terms given the competition among numerous pharmaceutical and biotechnology companies for similar personnel. We also experience competition for the hiring of scientific and clinical personnel from universities and research institutions. In addition, we rely on consultants and advisors, including scientific and clinical advisors, to assist us in formulating our research and development and commercialization strategy. Our consultants and advisors may be employed by employers other than us and may have commitments under consulting or advisory contracts with other entities that may limit their availability to us. If we are unable to continue to attract and retain high quality personnel, our ability to pursue our growth strategy will be limited.

In addition to our U.S. operations, we maintain a wholly owned subsidiary in Russia, Selecta RUS.(RUS). However, we plan to wind down these operations. We may face risks associated with maintaining our subsidiary in Russia, or with any international operations, including possible unfavorable regulatory, pricing and reimbursement, legal, political, tax and labor conditions, and risks associated with our compliance with evolving international sanctions, which could harm our business. We may also rely