Arcturus Therapeutics (ARCT) 10-Q 9 Nov 22 2022 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2022	Nov. 02, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
Trading Symbol	ARCT
Entity Registrant Name	ARCTURUS THERAPEUTICS HOLDINGS INC.
Entity Central Index Key	0001768224
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of 12(b) Security	Common Stock, par value $0.001 per share
Security Exchange Name	NASDAQ
Entity File Number	001-38942
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	32-0595345
Entity Address, Address Line One	10628 Science Center Drive
Entity Address, Address Line Two	Suite 250
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	900-2660
Entity Common Stock, Shares Outstanding		26,492,869
Document Quarterly Report	true
Document Transition Report	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 237,676	$ 370,492
Accounts receivable	2,044	3,367
Prepaid expenses and other current assets	6,960	5,102
Total current assets	246,680	378,961
Property and equipment, net	11,347	5,643
Operating lease right-of-use asset, net	33,519	5,618
Equity-method investment		515
Non-current restricted cash	2,081	2,077
Total assets	293,627	392,814
Current liabilities:
Accounts payable	17,962	10,058
Accrued liabilities	25,529	23,523
Current portion of long-term debt	27,702	22,474
Deferred revenue	4,656	43,482
Total current liabilities	75,849	99,537
Deferred revenue, net of current portion	5,179	19,931
Long-term debt, net of current portion	32,038	40,633
Operating lease liability, net of current portion	31,218	4,502
Other non-current liabilities	3,676
Total liabilities	147,960	164,603
Stockholders’ equity
Common stock, $0.001 par value; 60,000 shares authorized; issued and outstanding shares were 26,492 at September 30, 2022 and 26,372 at December 31, 2021	26	26
Additional paid-in capital	601,129	575,675
Accumulated deficit	(455,488)	(347,490)
Total stockholders’ equity	145,667	228,211
Total liabilities and stockholders’ equity	$ 293,627	$ 392,814

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	60,000,000	60,000,000
Common stock, shares issued	26,492,000	26,372,000
Common stock, shares outstanding	26,492,000	26,372,000

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Statement of Comprehensive Income [Abstract]
Revenue	$ 13,369	$ 2,437	$ 45,706	$ 6,565
Operating expenses:
Research and development, net	37,688	45,398	120,770	141,127
General and administrative	12,488	10,860	34,211	30,645
Total operating expenses	50,176	56,258	154,981	171,772
Loss from operations	(36,807)	(53,821)	(109,275)	(165,207)
Gain (loss) from equity-method investment		(250)	(515)	670
Gain from foreign currency	1,862	506	3,237	923
Finance expense, net	(321)	(519)	(1,445)	(1,397)
Net loss	$ (35,266)	$ (54,084)	$ (107,998)	$ (165,011)
Net loss per share, basic	$ (1.33)	$ (2.05)	$ (4.09)	$ (6.27)
Net loss per share, diluted	$ (1.33)	$ (2.05)	$ (4.09)	$ (6.27)
Weighted-average shares outstanding, basic	26,467	26,338	26,423	26,302
Weighted-average shares outstanding, diluted	26,467	26,338	26,423	26,302
Comprehensive loss:
Net loss	$ (35,266)	$ (54,084)	$ (107,998)	$ (165,011)
Comprehensive loss	$ (35,266)	$ (54,084)	$ (107,998)	$ (165,011)

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2020	$ 396,553	$ 26	$ 540,343	$ (143,816)
Balance (in shares) at Dec. 31, 2020		26,192
Net loss	(56,346)			(56,346)
Issuance of common stock related to acquired in-process research and development	5,000		5,000
Issuance of common stock related to acquired in-process research and development (in shares)		75
Share-based compensation expense	6,987		6,987
Issuance of common stock upon exercise of stock options	413		413
Issuance of common stock upon exercise of stock options (in shares)		52
Balance at Mar. 31, 2021	352,607	$ 26	552,743	(200,162)
Balance (in shares) at Mar. 31, 2021		26,319
Balance at Dec. 31, 2020	396,553	$ 26	540,343	(143,816)
Balance (in shares) at Dec. 31, 2020		26,192
Net loss	(165,011)
Balance at Sep. 30, 2021	259,126	$ 26	567,927	(308,827)
Balance (in shares) at Sep. 30, 2021		26,349
Balance at Mar. 31, 2021	352,607	$ 26	552,743	(200,162)
Balance (in shares) at Mar. 31, 2021		26,319
Net loss	(54,581)			(54,581)
Share-based compensation expense	7,540		7,540
Issuance of common stock upon exercise of stock options	82		82
Issuance of common stock upon exercise of stock options (in shares)		8
Balance at Jun. 30, 2021	305,648	$ 26	560,365	(254,743)
Balance (in shares) at Jun. 30, 2021		26,327
Net loss	(54,084)			(54,084)
Share-based compensation expense	6,870		6,870
Issuance of common stock upon exercise of stock options	177		177
Issuance of common stock upon exercise of stock options (in shares)		9
Issuance of common stock under equity plans	515		515
Issuance of common stock under equity plans (in shares)		13
Balance at Sep. 30, 2021	259,126	$ 26	567,927	(308,827)
Balance (in shares) at Sep. 30, 2021		26,349
Balance at Dec. 31, 2021	228,211	$ 26	575,675	(347,490)
Balance (in shares) at Dec. 31, 2021		26,372
Net loss	(51,169)			(51,169)
Share-based compensation expense	7,371		7,371
Issuance of common stock upon exercise of stock options	336		336
Issuance of common stock upon exercise of stock options (in shares)		35
Balance at Mar. 31, 2022	184,749	$ 26	583,382	(398,659)
Balance (in shares) at Mar. 31, 2022		26,407
Balance at Dec. 31, 2021	228,211	$ 26	575,675	(347,490)
Balance (in shares) at Dec. 31, 2021		26,372
Net loss	(107,998)
Balance at Sep. 30, 2022	145,667	$ 26	601,129	(455,488)
Balance (in shares) at Sep. 30, 2022		26,492
Balance at Mar. 31, 2022	184,749	$ 26	583,382	(398,659)
Balance (in shares) at Mar. 31, 2022		26,407
Net loss	(21,563)			(21,563)
Share-based compensation expense	7,274		7,274
Issuance of common stock upon exercise of stock options	257		257
Issuance of common stock upon exercise of stock options (in shares)		27
Balance at Jun. 30, 2022	170,717	$ 26	590,913	(420,222)
Balance (in shares) at Jun. 30, 2022		26,434
Net loss	(35,266)			(35,266)
Share-based compensation expense	9,436		9,436
Issuance of common stock upon exercise of stock options	369		369
Issuance of common stock upon exercise of stock options (in shares)		36
Issuance of common stock under equity plans	411		411
Issuance of common stock under equity plans (in shares)		22
Balance at Sep. 30, 2022	$ 145,667	$ 26	$ 601,129	$ (455,488)
Balance (in shares) at Sep. 30, 2022		26,492

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
OPERATING ACTIVITIES:
Net loss	$ (107,998)	$ (165,011)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	976	883
Share-based compensation expense	24,081	21,397
Acquired in-process research and development expense		5,000
Loss (gain) from equity-method investment	515	(670)
Foreign currency transaction gain	(2,976)	(923)
Other non-cash expenses	3,899	2,477
Changes in operating assets and liabilities
Accounts receivable	1,323	110
Prepaid expense and other assets	(1,858)	(2,302)
Accounts payable	5,335	(2,569)
Accrued liabilities	2,015	13,569
Deferred revenue	(53,578)	35,493
Net cash used in operating activities	(128,266)	(92,546)
INVESTING ACTIVITIES:
Acquisition of property and equipment	(3,919)	(2,288)
Net cash used in investing activities	(3,919)	(2,288)
FINANCING ACTIVITIES:
Proceeds from debt		46,599
Proceeds from exercise of stock options	962	672
Proceeds from the issuance of common stock under equity plans	411	515
Payments on debt obligations	(2,000)
Net cash used in (provided by) financing activities	(627)	47,786
NET (DECREASE) INCREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(132,812)	(47,048)
Cash, cash equivalents and restricted cash at beginning of the period	372,569	463,002
Cash, cash equivalents and restricted cash at end of the period	239,757	415,954
Supplemental disclosure of cash flow information
Cash paid for interest	585	514
Non-cash investing activities
Right-of-use assets acquired through operating leases	30,191	1,828
Acquisition of in-process research and development through issuance of common stock		5,000
Purchase of property and equipment in accounts payable and accrued expenses	$ 2,761	$ 60

Description of Business, Basis

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2022
Accounting Policies [Abstract]
Description of Business, Basis of Presentation and Summary of Significant Accounting Policies	Note 1. Description of Business, Basis of Presentation and Summary of Significant Accounting Policies Description of Business Arcturus Therapeutics Holdings Inc. (the “Company” or "Arcturus") is a global late-stage clinical messenger RNA medicines company focused on the development of infectious disease vaccines and significant opportunities within liver and respiratory rare diseases. The Company became a clinical stage company during 2020 when it announced that its Investigational New Drug (“IND”) application for ornithine transcarbamylase (“OTC”) deficiency and its Clinical Trial Application (“CTA”) for candidate LUNAR-COV19 were approved by applicable health authorities. Basis of Presentation The accompanying condensed consolidated financial statements include the accounts of Arcturus and its subsidiaries and are unaudited. All intercompany accounts and transactions have been eliminated in consolidation. These condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In management’s opinion, the accompanying condensed consolidated financial statements reflect all adjustments, consisting of normal recurring adjustments, considered necessary for a fair presentation of the results for the interim periods presented. Interim financial results are not necessarily indicative of results anticipated for the full year. These condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and footnotes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021. These condensed consolidated financial statements are prepared in accordance with GAAP, which requires management to make estimates and assumptions regarding the valuation of debt instruments, the equity-method investment, share-based compensation expense, accruals for liabilities, income taxes, revenue and deferred revenue, leases, and other matters that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. Although these estimates are based on management’s knowledge of current events and actions the Company may undertake in the future, actual results may ultimately differ from these estimates and assumptions. Joint Ventures, Equity Method Investments and Variable Interest Entities Investments for which the Company exercises significant influence, but does not have control are accounted for under the equity method. Equity method investment activity is related to a 49 % joint venture with Axcelead, Inc. (see the following paragraph for further details) and an 7 % ownership in Vallon Pharmaceuticals, Inc. (see “ Note 10, Related Party Transactions ” for further details). The Company’s share of the investees’ results is presented as either income or loss from equity method investees in the accompanying condensed consolidated statements of operations and comprehensive loss. In April 2021, Arcturus and Axcelead, Inc., a company existing under the laws of Japan (“Axcelead”), formed a joint venture entity, named Arcalis, Inc. (“JV Entity”), which operates as a corporation under the laws of Japan. Axcelead is an integrated drug discovery solutions provider to the pharmaceutical industry in Japan. On July 1, 2017, Axcelead became the successor to a portion of the drug discovery research department of Takeda Pharmaceutical Company Limited. The goal of the JV Entity is to be a contract development and manufacturing organization focused on mRNA manufacturing that would provide manufacturing services to the Company and also to third parties. The joint venture includes a shareholders agreement which sets forth initial funding of the JV Entity and rights of the JV Entity shareholders, including certain approval rights of Arcturus. As part of the joint venture, the Company entered into a License and Technology Transfer Agreement with the JV Entity, pursuant to which Arcturus grants to JV Entity a nonexclusive license to certain intellectual property for use at the JV Entity’s facilities, and obligates Arcturus to conduct certain technology transfer activities. The Company consolidates variable interest entities (“VIEs”) where it has been determined that the Company is the primary beneficiary of those entities’ operations. Management believes that power is shared between Arcturus and Axcelead, as unrelated parties. The consent of each of the parties is substantive and is required to make the decisions about the JV Entity’s significant activities. Management does not believe that Arcturus has the power to direct the activities of the JV Entity that most significantly impact the JV Entity’s economic performance. Therefore, the Company concluded it is not required to consolidate the JV Entity under the VIE model. The equity method of accounting is applicable for the JV Entity as the Company does not own more than 50 % of voting power, but has influence over the operation and financial policies of the investee. The Company accounts for its investment in the JV Entity using the equity method of accounting as specified in Accounting Standard Codification (“ASC”) 323, Investments — Equity Method and Joint Ventures. Under ASC 323, equity method investments are recorded initially at cost. The Company’s initial investment in the JV Entity totaled $ 9.2 million. However, the JV Entity paid back the Company's initial investment of $ 9.2 million as an upfront fee/consideration for the License and Technology Transfer Agreement. In substance, there was no cash consideration paid by the Company for its 49 % equity interest in the JV Entity. Liquidity The Company has incurred significant operating losses since its inception. As of September 30, 2022 and December 31, 2021, the Company had an accumulated deficit of $ 455.5 million and $ 347.5 million, respectively. The Company’s activities since inception have consisted principally of research and development activities, general and administrative activities, and raising capital. The Company’s activities are subject to significant risks and uncertainties, including failing to secure additional funding before the Company achieves sustainable revenues and profit from operations. From the Company’s inception through September 30, 2022, the Company has funded its operations principally with the proceeds from the sale of capital stock, revenues earned through collaboration agreements and proceeds from long-term debt. At September 30, 2022, the Company’s balance of cash and cash equivalents, including restricted cash, w as $ 239.8 million. Management believes that it has sufficient working capital on hand to fund operations through at least the next twelve months from the date these condensed consolidated financial statements were available to be issued. There can be no assurance that the Company will be successful in securing additional funding, that the Company’s projections of its future working capital needs will prove accurate, or that any additional funding would be sufficient to continue operations in future years. Segment Information In making decisions regarding resource allocation and assessing performance, the chief operating decision-maker identifies operating segments as components of an enterprise for which separate discrete financial information is available for evaluation. The Company and its chief operating decision-maker view the Company’s operations and manage its business in one operating segment, which is the research and development of medical applications for the Company’s nucleic acid-focused technology. Revenue Recognition The Company determines revenue recognition for arrangements within the scope of Topic 606 by performing the following five steps: (i) identify the contract; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when, or as, the Company satisfies a performance obligation. The terms of the Company’s revenue agreements include license fees, upfront payments, milestone payments, reimbursement for research and development activities, option exercise fees, transfer of drug substance, consulting and related technology transfer fees and royalties on sales of commercialized products. Arrangements that include upfront payments are recorded as deferred revenue upon receipt or when due and may require deferral of revenue recognition to a future period until the Company performs obligations under these arrangements. The event-based milestone payments represent variable consideration, and the Company uses the most likely amount method to estimate this variable consideration because the Company will either receive the milestone payment or will not, which makes the potential milestone payment a binary event. The most likely amount method requires the Company to determine the likelihood of earning the milestone payment. Given the high degree of uncertainty around achievement of these milestones, the Company determines the milestone amounts to be fully constrained and does not recognize revenue until the uncertainty associated with these payments is resolved. The Company will recognize revenue from sales-based royalty payments when or as the sales occur. The Company will re-evaluate the transaction price in each reporting period as uncertain events are resolved and other changes in circumstances occur. A performance obligation is a promise in a contract to transfer a distinct good or service to the collaborative partner and is the unit of account in Topic 606. A contract’s transaction price is allocated to each distinct performance obligation based on relative standalone selling price and recognized as revenue when, or as, the performance obligation is satisfied. Leases See “Note 9, Commitments and Contingencies” for specific details surrounding the Company’s leases. Research and Development, Net All research and development costs are expensed as incurred. Research and development costs consist primarily of salaries, share-based compensation, employee benefits, costs associated with preclinical studies and clinical trials (including amounts paid to clinical research organizations and other professional services), in process research and development expenses and license agreement expenses, net of any grants, and prelaunch inventory. Payments made prior to the receipt of goods or services to be used in research and development are capitalized until the goods or services are received. The Company records accruals for estimated research and development costs, comprising payments for work performed by third party contractors, laboratories, participating clinical trial sites, and others. Some of these contractors bill monthly based on actual services performed, while others bill periodically based upon achieving certain contractual milestones. For the latter, the Company accrues the expenses as goods or services are used or rendered. Clinical trial site costs related to patient enrollment are accrued as patients enter and progress through the trial. Pre-Launch Inventory Prior to obtaining initial regulatory approval for an investigational product candidate, the Company expenses costs relating to production of inventory as research and development expense in its condensed consolidated statements of operations and comprehensive loss, in the period incurred. When the Company believes regulatory approval and subsequent commercialization of an investigational product candidate is probable, and the Company also expects future economic benefit from the sales of the investigational product candidate to be realized, it will then capitalize the costs of production as inventory. Statement of Cash Flows The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the condensed consolidated balance sheet to the total of the same such amounts shown in the condensed consolidated statement of cash flows: (in thousands) September 30, 2022 September 30, 2021 Cash and cash equivalents $ 237,676 $ 413,880 Non-current restricted cash 2,081 2,074 Total cash, cash equivalents and restricted $ 239,757 $ 415,954 Net Loss per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding for the period, without consideration for common stock equivalents. Diluted net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock and dilutive common stock equivalents outstanding for the period determined using the treasury-stock method. No dividends were declared or paid during the reported periods. Recently Issued Accounting Standards Not Yet Adopted From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on our condensed consolidated financial statements and disclosures.

Revenue

Revenue	9 Months Ended
	Sep. 30, 2022
Revenue from Contract with Customer [Abstract]
Revenue	Note 2. Revenue The Company has entered into license agreements and collaborative research and development arrangements with pharmaceutical and biotechnology companies, as well as consulting, related technology transfer, drug substance transfer and product revenue agreements. Under these arrangements, the Company is entitled to receive license fees, consulting fees, product fees, technological transfer fees, upfront payments, milestone payments if and when certain research and development milestones or technology transfer milestones are achieved, royalties on approved product sales and reimbursement for research and development activities. The Company’s costs of performing these services are included within research and development expenses. The Company’s milestone payments are typically defined by achievement of certain preclinical, clinical, and commercial success criteria. Preclinical milestones may include in vivo proof of concept in disease animal models, lead candidate identification, and completion of IND-enabling toxicology studies. Clinical milestones may, for example, include successful enrollment of the first patient in or completion of Phase 1, 2 and 3 clinical trials, and commercial milestones are often tiered based on net or aggregate sale amounts. The Company cannot guarantee the achievement of these milestones due to risks associated with preclinical and clinical activities required for development of nucleic acid medicine-based therapeutics and vaccines. The following table presents changes during the nine months ended September 30, 2022 in the balances of contract assets, including receivables from collaborative partners, consulting and related technology transfer partners, and contract liabilities, including deferred revenue, as compared to what was disclosed in the Company’s Annual Report. (in thousands) Contract Assets BALANCE - December 31, 2021 $ 3,367 Additions for revenue recognized from billings 1,700 Deductions for cash collections ( 3,023 ) BALANCE – September 30, 2022 $ 2,044 (in thousands) Contract Liabilities BALANCE - December 31, 2021 $ 63,413 Additions for advanced billings 1,700 Reclassifications to accrued liabilities ( 9,572 ) Deductions for promised services provided in current period ( 45,706 ) BALANCE – September 30, 2022 $ 9,835 The following table summarizes the Company’s revenues for the periods indicated (in thousands). For the Three Months For the Nine Months (Dollars in thousands) 2022 2021 2022 2021 Vinbiocare $ 11,237 $ 600 $ 26,815 $ 600 Janssen 934 636 2,593 2,229 Ultragenyx 928 926 2,814 2,776 CureVac 225 241 673 713 Israel Ministry of Health — — 12,500 — Other 45 34 311 247 Total revenue $ 13,369 $ 2,437 $ 45,706 $ 6,565 The following paragraphs provide information regarding the nature and purpose of the Company’s most significant collaboration arrangements. Vinbiocare During 2021 the Company entered into certain agreements with Vinbiocare, a member of Vingroup Joint Stock Company, whereby the Company would provide technical expertise and support services to Vinbiocare to assist in the build out of a mRNA drug product manufacturing facility in Vietnam. The Company received an upfront payment in aggregate of $ 40.0 million as part of the Vinbiocare Agreement. In October 2022, the Company and Vinbiocare executed a letter agreement terminating the Technology License and Technical Support Agreement and the Framework Drug Substance Supply Agreement (collectively, the “License & Supply Agreements”). The Company incurred no financial penalties in connection with the termination of the License & Supply Agreements and has no further financial obligations to Vinbiocare under these terminated agreements. In association with the termination of the License & Supply Agreements, the Company signed in October 2022 the Study Support Agreement with Vinbiocare which provides for Vinbiocare to continue serving as the regulatory and financial sponsor of clinical studies conducted in Vietnam of ARCT-154. To support the continuing activities of these studies, the Study Support Agreement further provides for the Company to conduct certain services and to compensate Vinbiocare to help achieve the objectives of these studies. The Company has determined that the execution of the Study Support Agreement constitutes a type 1 subsequent event and the impact to the transaction price should be recognized as of September 30, 2022, as the contract negotiations began during the third quarter of 2022 and the conditions existed as of September 30, 2022 although not finalized until October 2022. The Company has reserved a portion of the original upfront payment to be paid to Vinbiocare over the future periods pursuant to the Study Support Agreement by reclassifying a portion of the upfront payment received from Vinbiocare pursuant to the License & Supply Agreements, from deferred revenue to short-term and long-term liabilities, based on the anticipated timing of the payments to Vinbiocare, and removed that portion of the upfront payment from the transaction price of the modified arrangement. The transaction price was not adjusted for payments that are contingent upon the occurrence of future regulatory or sales related events based on the information currently available to the Company. The Company has concluded that is has no remaining performance obligations as of September 30, 2022, and therefore has recognized the remaining transaction price of $ 11.2 million as revenue during the period ended September 30, 2022. As of September 30, 2022, the Company has accrued liabilities related to this arrangement of $ 5.9 million in current liabilities and $ 3.7 million in non-current liabilities that will be paid upon the occurrence of specified events through the first quarter of 2025. Vinbiocare is also eligible to receive a single digit percentage of amounts from net sales, if any, of ARCT-154 (or next-generation COVID vaccine) up to a capped amount of low single digit millions. The Company had no remaining deferred revenue as of September 30, 2022. As of December 31, 2021, the deferred revenue balance was $ 37.2 million. Janssen Pharmaceuticals, Inc., Ultragenyx Pharmaceutical Inc., CureVac AG For each of Janssen Pharmaceuticals, Inc. (“Janssen”), Ultragenyx Pharmaceutical Inc. (“Ultragenyx”) and CureVac AG (“CureVac”), the Company evaluated the respective agreement in accordance with ASC Topic 606. The Company concluded that the contract counterparty is a customer. The Company identified all promised goods/services within each agreement, and concluded that the promised goods/services are incapable of being distinct and consequently do not have any value on a standalone basis. Accordingly, the promised goods/services within each agreement were determined to represent a single performance obligation. Lastly, the Company concluded that any options to select additional collaboration targets and to license rights to selected targets were not priced at a discount and therefore do not represent performance obligations for which the transaction price would be allocated. Janssen In October 2017, the Company entered into a research collaboration and license agreement with Janssen (the “2017 Agreement”) to collaborate on developing candidates for treating HBV with RNA therapeutics. The 2017 Agreement allocated discovery, development, funding obligations, and ownership of related intellectual property among the Company and Janssen. As of September 30, 2022 , the remaining transaction price consisting of upfront consideration received, budgeted reimbursable out-of-pocket costs and a preclinical milestone payment of $ 1.0 million received in the fourth quarter of 2021, is expected to be recognized using an input method over the remaining research period. None of the remaining development and commercialization milestones were included in the transaction price as they are outside the control of the Company and contingent upon success in future clinical trials and the collaborator’s efforts. Any consideration related to sales-based royalties will be recognized when the related sales occur, provided that the reported sales are reliably measurable, and the Company has no remaining promised goods/services, as such sales were determined to relate predominantly to the license granted to Janssen and therefore have also been excluded from the transaction price. Total deferred revenue as of September 30, 2022 and December 31, 2021 for Jan ssen was $ 6.0 million and $ 6.3 million, respectively. On October 31, 2022, Janssen delivered to the Company notice of termination of the 2017 Agreement. The termination is effective 60 days after notice. The Company will not incur any penalties as a result of this termination. Ultragenyx In October 2015 the Company entered into a research collaboration and license agreement with Ultragenyx (as amended, the “Ultragenyx Agreement”), whereby Arcturus granted to Ultragenyx a co-exclusive license to certain Arcturus technology, which is in effect only during the reserve target exclusivity term as discussed in the following paragraphs. This collaboration agreement was amended in 2017, 2018 and during the second quarter of 2019. During the initial phase of the collaboration, the Company will design and optimize therapeutics for certain rare disease targets. Ultragenyx has the option under the Ultragenyx Agreement to add additional rare disease targets during the collaborative development period. Additionally, during the collaborative development period, the Company will participate with Ultragenyx in a joint steering committee. The current potential development, regulatory and commercial milestone payments for the existing development targets as of September 30, 2022 are $ 138.0 million. Ultragenyx will pay royalties as a single-digit percentage of net sales on a product-by-product and country-by-country basis during the applicable royalty term. As of September 30, 2022, Ultragenyx is working to identify and enroll patients in a Phase 1/2 study. As of September 30, 2022 , the transaction price included the upfront consideration received, option payments, exclusivity extension payments and additional consideration received pursuant to Amendment 3 of the Ultragenyx Agreement (“Amendment 3”). The Company recognizes the reimbursement of labor and expenses as costs are incurred and none of the development and commercialization milestones were included in the transaction price, as all milestone amounts were fully constrained. As part of its evaluation of the constraint, the Company considered numerous factors, including that the consideration is outside the control of the Company and contingent upon success in future clinical trials, approval from the FDA and the collaborator’s efforts. Any consideration related to sales-based royalties will be recognized when the related sales occur as they are constrained, provided that the reported sales are reliably measurable and the Company has no remaining promised goods/services, as such sales were determined to relate predominantly to the license granted to Ultragenyx and therefore have also been excluded from the transaction price. During the three months ended September 30, 2022 , no adjustments were made to the transaction price. Amendment 3 was deemed a contract modification and accounted for as part of the original Ultragenyx Agreement. The transaction price is recognized to revenue on a straight-line basis using an input method over the 4 -year reserve target exclusivity period. The reserve target exclusivity period represents the timing over which promised goods/services will be provided. Total deferred revenue at September 30, 2022 and December 31, 2021 from Ultragenyx was $ 2.8 million and $ 5.5 million, respectively. CureVac In January 2018 , the Company entered into a Development and Option Agreement (the “Development and Option Agreement”) with CureVac. Under the terms of the Development and Option Agreement, the parties agreed to conduct joint preclinical development programs once CureVac makes a payment to pull down a target on the basis of which CureVac is granted options for taking a license on pre-agreed license terms to develop and commercialize certain products incorporating the Company’s patents and know-how related to LUNAR ® delivery technology (the “Arcturus Delivery Technology”), and CureVac patents and know-how related to mRNA technology. As of September 30, 2022 , the transaction price included the upfront consideration received. The Company recognizes the reimbursement of labor and expenses as costs are incurred and none of the development and commercialization milestones were included in the transaction price, as all milestone amounts were fully constrained . As part of its evaluation of the constraint, the Company considered numerous factors, including that receipt of the milestones is outside the control of the Company and contingent upon success in future clinical trials and the collaborator’s efforts. Any consideration related to sales-based royalties will be recognized when the related sales occur as they are constrained, provided that the reported sales are reliably measurable and the Company has no remaining promised goods/services, as such sales were determined to relate predominantly to the license granted to CureVac and therefore have also been excluded from the transaction price. As of September 30, 2022 , no adjustments were made to the transaction price. The upfront consideration of $ 5.0 million was recorded as deferred revenue in the Company’s condensed balance sheet upon receipt and is currently being recognized as revenue on a straight-line basis using an input method over the remaining 10 month contractual term as of September 30, 2022. Total deferred revenue as of September 30, 2022 and December 31, 2021 for CureVac was $ 0.7 million and $ 1.4 million, respectively. Other Agreements In January 2022, the Company entered into an agreement with a pharmaceutical company, whereby the pharmaceutical company agreed to fund up to $ 25 million for a clinical trial for a LUNAR-COV19 vaccine candidate as a booster. The Company submitted billings from a third party of $ 4.9 million related to the clinical trial which falls under the expected funding of $ 25 million of the booster program. The Company received the $ 4.9 million reimbursement for the billings subsequent to September 30, 2022. The Company has not recognized any revenue associated with this agreement as of September 30, 2022. Israeli Ministry of Health On August 17, 2020, the Company entered into an agreement with the Israeli Ministry of Health (the “MOH”) to supply the Company’s COVID-19 vaccine candidate to Israel (the “Israel Supply Agreement”) subject to certain conditions, including applicable regulatory approvals. In October 2020, and in association with the Israel Supply Agreement, the Company received a non-refundable payment of $ 12.5 million from the MOH. This payment of $ 12.5 million is associated with a specified clinical trial milestone and serves as an initial reserve payment for a specified number of doses of the LUNAR-COV19 vaccine candidate pursuant to the Israel Supply Agreement. As a result of the making of this payment, the MOH became bound to purchase an initial quantity of 500,000 reserved vaccine doses, as set forth in and subject to the terms and conditions of the Israel Supply Agreement. Furthermore, the Israel Supply Agreement permitted termination by the MOH immediately upon written notice to Arcturus if the Company did not obtain certain regulatory approvals by December 31, 2021. On April 14, 2022, Arcturus received notice from the MOH to terminate the Israel Supply Agreement. Therefore, the Company recognized the payment as revenue during the second quarter of 2022 as there were no remaining performance obligations under the agreement. No termination penalties were incurred by the Company connection therewith.

Grant Revenue

Grant Revenue	9 Months Ended
	Sep. 30, 2022
Grant Revenue [Abstract]
Grant Revenue	Note 3. Grant Revenue BARDA Grant In August 2022, the Company entered into a cost reimbursement contract with the Biomedical Advanced Research and Development Authority ("BARDA"), a division of the Office of the Assistant Secretary for Preparedness and Response (ASPR) within the U.S. Department of Health and Human Services (HHS) for an award of up to $ 63.2 million for the development of a pandemic influenza vaccine using the Company's STARR™ self-amplifying mRNA vaccine platform technology. The Company earns grant revenue for performing tasks under the agreement. The Company determined that the agreement with BARDA is not in the scope of ASC 808 or ASC 606. Applying International Accounting Standards No. 20 ("IAS 20"), Accounting for Government Grants and Disclosure of Government Assistance, by analogy, the Company recognizes grant revenue from the reimbursement of direct out-of-pocket expenses, overhead allocations and fringe benefits for research costs associated with the grant. The costs associated with these reimbursements are reflected as a component of research and development expense in the Company’s condensed consolidated statements of operations. We recognized an immaterial amount of revenue during the three months ended September 30, 2022, which is included in revenue on the Company's condensed consolidated statements of operations. As of September 30, 2022, the remaining available funding net of revenue earned was $ 63.2 million.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 4. Fair Value Measurements The Company establishes the fair value of its assets and liabilities using the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The Company established a fair value hierarchy based on the inputs used to measure fair value. The three levels of the fair value hierarchy are as follows: Level 1: Quoted prices in active markets for identical assets or liabilities. Level 2: Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly. Level 3: Unobservable inputs in which little or no market data exists and are therefore determined using estimates and assumptions developed by the Company, which reflect those that a market participant would use. The carrying value of cash, restricted cash, accounts receivable, accounts payable, accrued liabilities and the Singapore loan approximate their respective fair values due to their relative short maturities. The carrying amounts of long-term debt for the amount drawn on the Company’s debt facility approximates fair value as the interest rate is variable and reflects current market rates. As of September 30, 2022 and December 31, 2021 , all assets measured at fair value on a recurring basis consisted of cash equivalents and money market funds, which were classified within Level 1 of the fair value hierarchy. The fair value of these financial instruments was measured based on quoted prices.

Balance Sheet Details

Balance Sheet Details	9 Months Ended
	Sep. 30, 2022
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Details	Note 5. Balance Sheet Details Property and equipment, net balances consisted of the following: (in thousands) September 30, 2022 December 31, 2021 Research equipment $ 8,584 $ 6,735 Computers and software 1,038 488 Office equipment and furniture 958 574 Leasehold improvements 2,486 44 Construction in progress 3,513 2,058 Total 16,579 9,899 Less accumulated depreciation and amortization ( 5,232 ) ( 4,256 ) Property and equipment, net $ 11,347 $ 5,643 Depreciation and amortization expense was $ 0.4 million and $ 0.3 million for the three months ended September 30, 2022 and 2021 , and $ 1.0 million and $ 0.9 million for the nine months ended September 30, 2022 and 2021, respectively. Construction in progress primarily includes research equipment that is expected to be placed into service during 2022. Accrued liabilities consisted of the following: (in thousands) September 30, 2022 December 31, 2021 Accrued compensation $ 7,802 $ 3,578 Cystic Fibrosis Foundation liability (Note 9) — 2,777 Current portion of operating lease liability 3,783 1,537 Clinical accruals 2,026 8,675 Vinbiocare contractual liabilities 5,896 — Other accrued research and development expenses 6,022 6,956 Total $ 25,529 $ 23,523

Debt

Debt	9 Months Ended
	Sep. 30, 2022
Debt Disclosure [Abstract]
Debt	Note 6. Debt Manufacturing Supply Agreement On November 7, 2020, the Company’s wholly-owned subsidiary, Arcturus Therapeutics, Inc., entered into a Manufacturing Support Agreement (the “Support Agreement”) with the Economic Development Board of the Republic of Singapore (the “EDB”). Pursuant to the Support Agreement, the EDB agreed to make a term loan (the “Singapore Loan”) of S$ 62.1 million to the Company, subject to the satisfaction of customary deliveries, to support the manufacture of the LUNAR-COV19 vaccine candidate (ARCT-021). The Singapore Loan accrues inte rest at a rate of 4.5 % per annum calculated on a daily basis. The Company elected to borrow the full amount available under the Support Agreement of S$ 62.1 million ($ 46.6 million) on January 29, 2021. The EDB agreed to an extension of the reconciliation period to March 31, 2022, with unused funds as of such date returned to the EDB within 30 days following the completion of the customary audit and signed amendment of the Singapore Loan . This audit is scheduled to be completed during the fourth quarter of 2022. During the third quarter of 2022, the Company reported a portion of the Singapore Loan as current to reflect a potential principal repayment that is pending audit completion of approximately S$ 20.9 million ($ 15.7 million) in fiscal year 2022 based on amounts not used towards the manufacture of ARCT-021, and expects to refund this portion in the first quarter of fiscal year 2023. The Singapore Loan was initially recorded as long-term debt at $ 46.6 million, the amount of cash proceeds at the time the Company received the funding. During the first quarter of 2022, accrued interest of $ 1.9 million related to 2021 was added to the principal debt balance in accordance with the terms of the Support Agreement and the balance was adjusted to reflect the current exchange rate resulting in an increase in the debt balance to $ 47.8 million. The Company recorded a net foreign currency transaction gain of $ 3.0 million for the nine months ended September 30, 2022 compared to a net foreign currency transaction gain of $ 0.9 million for the nine months ended September 30, 2021. For the three and nine months ended September 30, 2022, the Company recorded interest expense and a corresponding liability of $ 0.5 million and $ 1.6 million, respectively, compared to interest expense and a corresponding liability of $ 0.5 million and $ 1.4 million for the three and nine months ended September 30, 2021, respectively. As of September 30, 2022, the Company was in compliance with all covenants under the Singapore Loan and related commitments. Long-term debt with Western Alliance Bank On October 12, 2018, Arcturus Therapeutics, Inc. entered into the loan with Western Alliance Bank (the "Bank"), whereby it received $ 10.0 million (the "Loan"). The Loan is collateralized by all of the assets of Arcturus Therapeutics, Inc., excluding intellectual property, which is subject to a negative pledge. The Loan contains customary conditions of borrowing, events of default and covenants, including covenants that restrict Arcturus Therapeutics, Inc.’s ability to dispose of assets, merge with or acquire other entities, incur indebtedness and make distributions to holders of its capital stock. In addition, Arcturus Therapeutics, Inc. is required to maintain at least 100 % of its consolidated, unrestricted cash, or $ 15.0 million, whichever is lower, with the Bank. On October 30, 2019, Arcturus Therapeutics, Inc. and the Bank entered into a Third Amendment (the “Third Amendment”) to the Loan (as amended, the “Loan Agreement”). Pursuant to the amendment, the Bank agreed to make a term loan to Arcturus Therapeutics, Inc. on October 30, 2019, in the amount of $ 15.0 million (the “Term Loan”). The resulting net increase in the indebtedness of Arcturus Therapeutics, Inc. was $ 5.0 million. The Term Loan bears interest at a floating rate ranging from 1.25 % to 2.75 % above the prime rate. The amendment further provides that the Term Loan has a maturity date of October 30, 2023 . Arcturus Therapeutics, Inc. will make monthly payments of interest only until October 1, 2021 . The Fourth Amendment was executed in connection with the Singapore Loan. In October of 2021, the Company and the Bank entered into a Fifth Amendment to Loan Agreement that provided for a six month extension to the interest only period which moved the first principal payment to May 1, 2022 . In April of 2022, the Company and the Bank entered into a Sixth Amendment to Loan Agreement that provided for a three month extension to the interest only period which moved the first principal payment to August 1, 2022 . Arcturus Therapeutics, Inc. paid a loan origination fee of $ 54,000 which was recorded as a debt discount along with the remaining loan origination fee from the Loan and is being accreted over the term of the Term Loan. In addition, Arcturus Therapeutics, Inc. is required to pay a fee of $ 525,000 upon certain change of control events. The Term Loan may be prepaid in full at any time, subject to a prepayment fee ranging from 0.50 % to 2.00 % of the prepaid principal amount depending upon the date of the prepayment. Upon maturity or prepayment (as previously discussed), Arcturus Therapeutics, Inc. will be required to pay a 2 % fee as a result of the FDA’s approval to proceed with the Company’s LUNAR-OTC program based on its IND submission. Such fee is accreted to the long-term debt balance using the effective interest method over the term of the Loan Agreement. Should an event of default occur, including the occurrence of a material adverse effect, the Company could be liable for immediate repayment of all obligations under the Loan Agreement. As of September 30, 2022, the Company was in compliance with all covenants under the Loan Agreement. Principal payments, including the final payment due at repayment, on the long-term debt are as follows as of September 30, 2022: (in thousands) 2022 $ 3,000 2023 10,300 Total $ 13,300 The Company recognized interest expense related to its long-term debt of $ 0.7 million during each of the three months ended September 30, 2022 and 2021, and $ 2.1 million and $ 2.0 million during the nine months ended September 30, 2022 and 2021, respectively.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2022
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Note 7. Stockholders’ Equity Alexion Pharmaceuticals License Agreement On February 17, 2021, the Company entered into an exclusive license agreement with Alexion Pharmaceuticals, Inc. (“ Alexion ”) pursuant to which Alexion granted to the Company an exclusive, worldwide license to exploit certain specified Alexion patent applications. In accordance with the terms of the license agreement, and in exchange for the license, the Company issued 74,713 shares of its common stock to Alexion on February 19, 2021 valued at approximately $ 5.0 million. The number of shares issued under the agreement was calculated by dividing (i) five million dollars ($5.0 million) by (ii) the volume-weighted average price per share of the Company’s common stock on the Nasdaq Global Market for the thirty (30) trading days immediately preceding the effective date of the license agreement (rounded to the nearest whole share). The Company recorded the transaction as an asset purchase as management concluded that all of the value received was related to a single identifiable asset. Further, the Company concluded that there was no alternative future use for the asset and recorded a charge at the closing of the transaction for the full $ 5.0 million value assigned to the shares issued in connection with the license agreement. This non-cash charge was recorded as acquired in-process research and development expense in the statements of operations and comprehensive loss. Net Loss per Share Dilutive securities that were not included in the calculation of diluted net loss per share for the three and nine months ended September 30, 2022 as they were anti-dilutive totaled 507,021 and 650,144 , respectively, and 1,457,223 and 1,514,023 for the three and nine months ended September 30, 2021.

Share-Based Compensation Expens

Share-Based Compensation Expense	9 Months Ended
	Sep. 30, 2022
Share-Based Payment Arrangement [Abstract]
Share-Based Compensation Expense	Note 8. Share-Based Compensation Expense In June 2022 at the Company’s 2022 Annual Meeting of Stockholders (the "2022 Annual Meeting"), the stockholders of the Company approved an amendment to the Company’s 2019 Omnibus Equity Incentive Plan (as amended, the “2019 Plan”) which, among other things, increases the aggregate number of shares authorized for use in making awards to eligible persons under the 2019 Plan by 3,750,000 shares, for a total of up to 8,750,000 shares available for issuance. On June 30, 2022, the Company filed a Form S-8 with the Commission to register the issuance of up to 3,750,000 additional shares following the 2022 Annual Meeting. As of September 30, 2022, a total of 3,490,857 shares remain available for future issuance under the 2019 Plan, subject to the terms of the 2019 Plan. In October 2021, the Company adopted the 2021 Inducement Equity Incentive Plan which covers the award of up to 1,000,000 shares of common stock (the “2021 Plan”) effective as of October 15, 2021. Approval of the Company’s stockholders will not be required as a condition to the effectiveness of the 2021 Plan for so long as the plan is in compliance with applicable Nasdaq inducement plan rules. On October 20, 2021, the Company filed a Form S-8 with the Commission to register the issuance of up to 1,000,000 shares underlying awards under the 2021 Plan. In April 2022, the compensation committee of the Company’s board of directors approved a proposal to reduce the total number of shares available for future issuance under the 2021 Plan to 130,000 . As of September 30, 2022, a total of 70,400 shares remain available for future issuance under the 2021 Plan, subject to the terms of the 2021 Plan. Stock Options Share-based compensation expense included in the Company’s condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2022 and 2021 was as follows: For the Three Months For the Nine Months (in thousands) 2022 2021 2022 2021 Research and development $ 3,996 $ 3,304 $ 10,811 $ 10,132 General and administrative 5,440 3,566 13,270 11,265 Total $ 9,436 $ 6,870 $ 24,081 $ 21,397

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2022
Income Tax Disclosure [Abstract]
Income Taxes	Note 9. Income Taxes The Company is subject to taxation in the United States and various states. The Company computes its quarterly income tax provision by using a forecasted annual effective tax rate and adjusts for any discrete items arising during the quarter. The primary difference between the effective tax rate and the federal statutory tax rate relates to the valuation allowances on the Company’s net operating losses. For the three and nine months ended September 30, 2022 and 2021, the Company recorded no income tax expense. No tax benefit was provided for losses incurred in United States because those losses are offset by a full valuation allowance.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 10. Commitments and Contingencies COVID-19 Vaccine Development On March 4, 2020, the Company was awarded a grant (“Grant 1”) from the Singapore EDB to support the co-development of a potential COVID-19 vaccine with the Duke-NUS Medical School. The Grant provides for up to S$ 14.0 million (approximately US$ 10.0 million using the exchange rate at the time the grant contract was entered into) in grants to support the development of the vaccine. The Grant has been paid in full by the EDB as a result of the achievement of certain milestones related to the progress of the development of the vaccine, as set forth in the award agreement. The funds received have been recognized as contra research and development expense. The parties are in continued negotiations with respect to amendments of Grant 1. Currently, the Company is liable for certain expenses during the program and is also subject to certain conditions including the requirement to pay an agreed upon royalty rate to Duke-NUS on future net sales of the LUNAR-COV19 ARCT-021 vaccine candidate developed with Duke-NUS in markets or jurisdictions outside of Singapore. The Company did not recognize any contra expense related to Grant 1 for the three months ended September 30, 2022 or 2021. The Company did not recognize any contra expense for the nine months ended September 30, 2022, but recognized $ 1.3 million of c ontra expense for the nine months ended September 30, 2021 related to Grant 1. As of September 30, 2022 and December 31, 2021, no amount remained in accrued expenses. On October 2, 2020, the Company was awarded another grant (“Grant 2”) from the Singapore EDB to support the clinical development of a potential COVID-19 vaccine (ARCT-021). The grant provides for up to S$ 9.3 million (approximately US$ 6.7 million) to support the clinical development of the vaccine candidate for costs incurred in Singapore subject to certain conditions. The grant is paid in two installments upon the achievement of certain milestones related to the progress of the development of the vaccine candidate. The Company received the first installment of $ 3.6 million in the fourth quarter of 2020. The funds received are recognized as contra research and development expense as costs are incurred. During 2021, the Company recognized the remaining amount of the first installment as contra research and development expense for Grant 2. During the first quarter of 2022, the Company and EDB concluded negotiations on this Contract, and thereby reduced the overall amount received by the Company under the Grant to the first installment of $ 3.6 million. The EDB agreed to an extension of the reconciliation period to March 31, 2022, with unused funds as of such date returned to the EDB within 30 days following the completion of the customary audit and signed amendment of the Singapore Loan. The audit and amendment is expected to be completed during the fourth quarter of 2022. Cystic Fibrosis Foundation Agreement On August 1, 2019, the Company amended its Development Program Letter Agreement, dated May 16, 2017 and as amended July 13, 2018, with the Cystic Fibrosis Foundation (“CFF”). Pursuant to the amendment, (i) CFF increased the amount it will award to advance LUNAR-CF to $ 15.0 million from approximately $ 3.2 million, (ii) the Company will provide $ 5.0 million in matching funds for remaining budgeted costs, (iii) the related disbursement schedule from CFF to Arcturus will be modified such that (a) $ 4.0 million will be disbursed upon execution of the CFF Amendment, (b) $ 2.0 million will be disbursed within 30 days of the first day of each of January, April, July and October 2020 upon Arcturus invoicing CFF to meet project goals, and (c) the last payment of $ 3.0 million less the prior award previously paid out, equaling approximately $ 2.3 million, will be disbursed upon Arcturus Sub invoicing CFF to meet good manufacturing practices and opening an Investigational New Drug (“IND”) application. The funds received from CFF are recognized as contra research and development expense in proportion to the p ercentage covered by CFF of the overall budget. For the three months ended September 30, 2022 and 2021, the Company recognized contra expense of $ 0.5 million and $ 1.6 million, respectively, and for the nine months ended September 30, 2022 and 2021, the Company recognized contra expense of $ 2.7 million and $ 3.1 million, respectively. As of September 30, 2022 and December 31, 2021, $ 0.0 million and $ 2.8 million, respectively, remained in accrued liabilities. Leases In October 2017, the Company entered into a non-cancellable operating lease agreement for office space adjacent to its previously occupied headquarters. The commencement of the lease began in March 2018 and the lease extends for approximately 84 months from the commencement date with a remaining lease term through March 2025. Monthly rental payments are due under the lease and there are escalating rent payments during the term of the lease. The Company is also responsible for its proportional share of operating expenses of the building and common areas. In conjunction with the new lease, the Company received free rent for four months and received a tenant improvement allowance of $ 74,000 . The lease may be extended for one five-year period at the then current market rate with annual escalations; however, the Company deemed the extension option not reasonably certain to be exercised and therefore excluded the option from the lease terms. The Company entered into an irrevocable standby letter of credit with the landlord for a security deposit of $ 96,000 upon executing the lease which is included (along with additional funds required to secure the letter of credit) in the balance of non-current restricted cash. In February 2020, the Company entered into a second non-cancellable operating lease agreement for office space near its current headquarters. The lease extended for 13 months from the commencement date and included a right to extend the lease for one twelve-month period. In February 2021, the Company opted to extend the lease through March 2025 to coincide with the lease term of the Company’s headquarters . In February 2021, the Company entered into a third non-cancellable operating lease agreement for office space near its current headquarters. The lease extends for 12 months from the commencement date with monthly base rent of approximately $ 11,000 . During the third quarter of 2021, the Company opted to extend the lease for an additional 12 months . In September 2021, the Company entered into a fourth non-cancellable lease agreement for office, research and development, engineering and laboratory space near its current headquarters. The initial term of the lease will extend ten years and eight month s from the date of possession, and the Company will have the right to extend the term of the lease for an additional five-year period . When the lease term was determined for our operating lease right-of-use assets and lease liabilities, the extension option for the lease was not included. The lease has a monthly base rent ranging from $ 268,000 to $ 360,000 which escalates over the lease term. The Com pany received a free rent period of four months and also pays for various operating costs, including utilities and real property taxes. The Company entered into an irrevocable standby letter of credit with the landlord for a security deposit of $ 2.0 million upon executing the lease which is included (along with additional funds required to secure the letter of credit) in the balance of non-current restricted cash. The lease term commenced during the second quarter of 2022. Operating lease right-of-use asset and liability on the condensed consolidated balance sheets represent the present value of remaining lease payments over the remaining lease terms. The Company does not allocate lease payments to non-lease components; therefore, payments for common-area-maintenance and administrative services are not included in the operating lease right-of-use asset and liability. The Company uses its incremental borrowing rate to calculate the present value of the lease payments, as the implicit rate in the lease is not readily determinable. As of September 30, 2022, the remaining payments of the operating lease liability were as follows: (in thousands) Remaining Lease Payments 2022 $ 1,338 2023 5,482 2024 5,646 2025 4,019 2026 3,603 Thereafter 23,282 Total remaining lease payments 43,370 Less: imputed interest ( 8,369 ) Total operating lease liabilities $ 35,001 Weighted-average remaining lease term 9.0 years Weighted-average discount rate 5.0 % Operating lease costs consist of the fixed le ase payments included in operating lease liability and are recorded on a straight-line basis over the lease terms. Operating lease costs were $ 1.4 million and $ 0.5 million for the three months ended September 30, 2022 and 2021, respectively, and $ 3.3 million and $ 1.4 million for t he nine months ended September 30, 2022 and 2021, respectively.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2022
Related Party Transactions [Abstract]
Related Party Transactions	Note 11. Related Party Transactions Equity-Method Investment In June 2018, the Company completed the sale of its intangible asset related to the ADAIR technology. Pursuant to the asset purchase agreement for ADAIR, the Company received a 30 % ownership interest in the common stock of Vallon Pharmaceuticals, Inc. (“Vallon”) in consideration for the sale of the ADAIR technology. The Company has no requirement to invest further in Vallon. Vallon completed an initial public offering and began trading on The Nasdaq Stock Market under the ticker “VLON” in February 2021. Additionally, Vallon executed the sale of 3,700,000 shares of common stock through a private placement in May 2022 as well as an exercise of warrants for 2,220,000 shares of common stock in August 2022. As a result, Arcturus owns 843,750 shares of Vallon, or approximately 7 %. Based on the Company’s ownership and the Vallon board of directors seat held by an executive of Arcturus, the Company has the ability to exercise significant influence over the operating and financial policies of Vallon; therefore, the Company accounts for this investment as an equity-method investment. The Company accounts for its share of the earnings or losses of the investee with a reporting lag of three months, as the financial statements of the investee are not completed on a basis that is sufficient for the Company to apply the equity method on a current basis. The warrant exercise was at a share price of $ 0.94 , greater than the initial investment which resulted in the Company recording a gain in its equity-method investment. Using a three month lag, the gain has been fully offset by losses incurred by Vallon through June 30, 2022. See “Note 1, Joint Ventures, Equity Method Investments and Variable Interest Entities” for specific details surrounding the Company’s agreement with Axcelead to form the joint venture entity, Arcalis, Inc.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2022
Subsequent Events [Abstract]
Subsequent Events	Note 12. Subsequent Events CSL Seqirus On November 1, 2022, the Company entered into a collaboration and license agreement (the "Collaboration Agreement”) with Seqirus, Inc., a part of CSL Limited (“CSL Seqirus”), one of the world’s leading influenza vaccine providers, for the research, development, manufacture and global commercialization of self-amplifying mRNA vaccines. CSL Seqirus will receive exclusive global access to Arcturus’ technology for vaccines against SARS-CoV-2 (COVID-19), influenza and three other globally prevalent respiratory infectious diseases. Specifically, the Collaboration Agreement grants CSL Seqirus a license to Arcturus’ STARRTM mRNA technology and LUNAR® lipid-mediated delivery, as well as mRNA drug substance and drug product manufacturing expertise. CSL Seqirus would also receive global non-exclusive access to Arcturus’ intellectual property rights in the field of pandemic preparedness (i.e., pathogens identified as priority diseases by the World Health Organization), with the right to convert to an exclusive license. Arcturus will receive an upfront payment of $ 200 million. Arcturus will be eligible to potentially receive development milestones totaling more than $ 1.3 billion if all products are registered in the licensed fields. Arcturus will also be entitled to potentially receive up to $ 3 billion in commercial milestones based on “net sales” of vaccines in the various fields. In addition, Arcturus is entitled to receive a 40 % share of net profits from COVID-19 vaccine sales and up to low double digit royalties of annual net sales for vaccines against influenza and the other three specified infectious disease pathogens, as well as royalties on revenues from vaccines that may be developed for pandemic preparedness. Entitlement to all such payments is subject to the strict conditions, requirements, royalties reduction provisions and other limitations set forth in the Collaboration Agreement. The Collaboration Agreement sets forth how the Company and CSL Seqirus shall collaborate to research and develop vaccine candidates. In the COVID-19 field, the Company will lead activities for certain regulatory filings for ARCT-154 in the US and Europe and for research and development activities of a next-generation COVID vaccine candidate. CSL Seqirus will lead and be responsible for all other research and development in COVID-19, influenza and the other fields. Arcturus will provide to CSL Seqirus a credit over five years to offset expenses of research and development activities (but not against milestone payments) on non-COVID-19 programs that Arcturus conducts at the request of CSL Seqirus. CSL Seqirus will have the sole right to commercialize any products that may be developed. The Collaboration Agreement will not become effective until expiration of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act. Either party may terminate the agreement on a field-by-field basis for material breach by the other party, following notice and opportunity to cure. CSL Seqirus may also terminate the Collaboration Agreement in its entirety or on a field-by-field basis for any reason or no reason whatsoever, but may not exercise this termination “for convenience” of the entire agreement or with respect to the influenza field prior to the first commercial sale of a “vaccine product” in the US, Japan, Australia or specified European countries. The Collaboration Agreement may also be terminated by CSL Seqirus for safety reasons, clinical data nonviability, commercial nonviability and other specified reasons. The Collaboration Agreement allows the Company to fulfill its obligations under its award from the Biomedical Advanced Research and Development Authority (BARDA) relating to rapid pandemic influenza response and announced by the Company in August 2022. Janssen On October 31, 2022, Arcturus received notice of termination from Janssen Pharmaceuticals, Inc. of the Research Collaboration and License Agreement, by and between Arcturus Therapeutics, Inc. and Janssen Pharmaceuticals, Inc., dated October 18, 2017 (the “Janssen Agreement”). The Janssen Agreement provided for the parties to collaborate on developing nucleic acid-based therapeutic candidates for the treatment of Hepatitis B. The Janssen Agreement was terminated in its entirety by Janssen for convenience. Arcturus will not incur any penalties as a result of this termination. The termination is effective 60 days after notice.

Description of Business, Basi_2

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements include the accounts of Arcturus and its subsidiaries and are unaudited. All intercompany accounts and transactions have been eliminated in consolidation. These condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In management’s opinion, the accompanying condensed consolidated financial statements reflect all adjustments, consisting of normal recurring adjustments, considered necessary for a fair presentation of the results for the interim periods presented. Interim financial results are not necessarily indicative of results anticipated for the full year. These condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and footnotes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021. These condensed consolidated financial statements are prepared in accordance with GAAP, which requires management to make estimates and assumptions regarding the valuation of debt instruments, the equity-method investment, share-based compensation expense, accruals for liabilities, income taxes, revenue and deferred revenue, leases, and other matters that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. Although these estimates are based on management’s knowledge of current events and actions the Company may undertake in the future, actual results may ultimately differ from these estimates and assumptions.
Joint Ventures, Equity Method Investments and Variable Interest Entities	Joint Ventures, Equity Method Investments and Variable Interest Entities Investments for which the Company exercises significant influence, but does not have control are accounted for under the equity method. Equity method investment activity is related to a 49 % joint venture with Axcelead, Inc. (see the following paragraph for further details) and an 7 % ownership in Vallon Pharmaceuticals, Inc. (see “ Note 10, Related Party Transactions ” for further details). The Company’s share of the investees’ results is presented as either income or loss from equity method investees in the accompanying condensed consolidated statements of operations and comprehensive loss. In April 2021, Arcturus and Axcelead, Inc., a company existing under the laws of Japan (“Axcelead”), formed a joint venture entity, named Arcalis, Inc. (“JV Entity”), which operates as a corporation under the laws of Japan. Axcelead is an integrated drug discovery solutions provider to the pharmaceutical industry in Japan. On July 1, 2017, Axcelead became the successor to a portion of the drug discovery research department of Takeda Pharmaceutical Company Limited. The goal of the JV Entity is to be a contract development and manufacturing organization focused on mRNA manufacturing that would provide manufacturing services to the Company and also to third parties. The joint venture includes a shareholders agreement which sets forth initial funding of the JV Entity and rights of the JV Entity shareholders, including certain approval rights of Arcturus. As part of the joint venture, the Company entered into a License and Technology Transfer Agreement with the JV Entity, pursuant to which Arcturus grants to JV Entity a nonexclusive license to certain intellectual property for use at the JV Entity’s facilities, and obligates Arcturus to conduct certain technology transfer activities. The Company consolidates variable interest entities (“VIEs”) where it has been determined that the Company is the primary beneficiary of those entities’ operations. Management believes that power is shared between Arcturus and Axcelead, as unrelated parties. The consent of each of the parties is substantive and is required to make the decisions about the JV Entity’s significant activities. Management does not believe that Arcturus has the power to direct the activities of the JV Entity that most significantly impact the JV Entity’s economic performance. Therefore, the Company concluded it is not required to consolidate the JV Entity under the VIE model. The equity method of accounting is applicable for the JV Entity as the Company does not own more than 50 % of voting power, but has influence over the operation and financial policies of the investee. The Company accounts for its investment in the JV Entity using the equity method of accounting as specified in Accounting Standard Codification (“ASC”) 323, Investments — Equity Method and Joint Ventures. Under ASC 323, equity method investments are recorded initially at cost. The Company’s initial investment in the JV Entity totaled $ 9.2 million. However, the JV Entity paid back the Company's initial investment of $ 9.2 million as an upfront fee/consideration for the License and Technology Transfer Agreement. In substance, there was no cash consideration paid by the Company for its 49 % equity interest in the JV Entity.
Liquidity	Liquidity The Company has incurred significant operating losses since its inception. As of September 30, 2022 and December 31, 2021, the Company had an accumulated deficit of $ 455.5 million and $ 347.5 million, respectively. The Company’s activities since inception have consisted principally of research and development activities, general and administrative activities, and raising capital. The Company’s activities are subject to significant risks and uncertainties, including failing to secure additional funding before the Company achieves sustainable revenues and profit from operations. From the Company’s inception through September 30, 2022, the Company has funded its operations principally with the proceeds from the sale of capital stock, revenues earned through collaboration agreements and proceeds from long-term debt. At September 30, 2022, the Company’s balance of cash and cash equivalents, including restricted cash, w as $ 239.8 million. Management believes that it has sufficient working capital on hand to fund operations through at least the next twelve months from the date these condensed consolidated financial statements were available to be issued. There can be no assurance that the Company will be successful in securing additional funding, that the Company’s projections of its future working capital needs will prove accurate, or that any additional funding would be sufficient to continue operations in future years.
Segment Information	Segment Information In making decisions regarding resource allocation and assessing performance, the chief operating decision-maker identifies operating segments as components of an enterprise for which separate discrete financial information is available for evaluation. The Company and its chief operating decision-maker view the Company’s operations and manage its business in one operating segment, which is the research and development of medical applications for the Company’s nucleic acid-focused technology.
Revenue Recognition	Revenue Recognition The Company determines revenue recognition for arrangements within the scope of Topic 606 by performing the following five steps: (i) identify the contract; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when, or as, the Company satisfies a performance obligation. The terms of the Company’s revenue agreements include license fees, upfront payments, milestone payments, reimbursement for research and development activities, option exercise fees, transfer of drug substance, consulting and related technology transfer fees and royalties on sales of commercialized products. Arrangements that include upfront payments are recorded as deferred revenue upon receipt or when due and may require deferral of revenue recognition to a future period until the Company performs obligations under these arrangements. The event-based milestone payments represent variable consideration, and the Company uses the most likely amount method to estimate this variable consideration because the Company will either receive the milestone payment or will not, which makes the potential milestone payment a binary event. The most likely amount method requires the Company to determine the likelihood of earning the milestone payment. Given the high degree of uncertainty around achievement of these milestones, the Company determines the milestone amounts to be fully constrained and does not recognize revenue until the uncertainty associated with these payments is resolved. The Company will recognize revenue from sales-based royalty payments when or as the sales occur. The Company will re-evaluate the transaction price in each reporting period as uncertain events are resolved and other changes in circumstances occur. A performance obligation is a promise in a contract to transfer a distinct good or service to the collaborative partner and is the unit of account in Topic 606. A contract’s transaction price is allocated to each distinct performance obligation based on relative standalone selling price and recognized as revenue when, or as, the performance obligation is satisfied.
Leases	Leases See “Note 9, Commitments and Contingencies” for specific details surrounding the Company’s leases.
Research and Development, Net	Research and Development, Net All research and development costs are expensed as incurred. Research and development costs consist primarily of salaries, share-based compensation, employee benefits, costs associated with preclinical studies and clinical trials (including amounts paid to clinical research organizations and other professional services), in process research and development expenses and license agreement expenses, net of any grants, and prelaunch inventory. Payments made prior to the receipt of goods or services to be used in research and development are capitalized until the goods or services are received. The Company records accruals for estimated research and development costs, comprising payments for work performed by third party contractors, laboratories, participating clinical trial sites, and others. Some of these contractors bill monthly based on actual services performed, while others bill periodically based upon achieving certain contractual milestones. For the latter, the Company accrues the expenses as goods or services are used or rendered. Clinical trial site costs related to patient enrollment are accrued as patients enter and progress through the trial.
Pre-Launch Inventory	Pre-Launch Inventory Prior to obtaining initial regulatory approval for an investigational product candidate, the Company expenses costs relating to production of inventory as research and development expense in its condensed consolidated statements of operations and comprehensive loss, in the period incurred. When the Company believes regulatory approval and subsequent commercialization of an investigational product candidate is probable, and the Company also expects future economic benefit from the sales of the investigational product candidate to be realized, it will then capitalize the costs of production as inventory.
Statement of Cash Flows	Statement of Cash Flows The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the condensed consolidated balance sheet to the total of the same such amounts shown in the condensed consolidated statement of cash flows: (in thousands) September 30, 2022 September 30, 2021 Cash and cash equivalents $ 237,676 $ 413,880 Non-current restricted cash 2,081 2,074 Total cash, cash equivalents and restricted $ 239,757 $ 415,954
Net Loss per Share	Net Loss per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding for the period, without consideration for common stock equivalents. Diluted net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock and dilutive common stock equivalents outstanding for the period determined using the treasury-stock method. No dividends were declared or paid during the reported periods.
Recently Issued Accounting Standards Not Yet Adopted	Recently Issued Accounting Standards Not Yet Adopted From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on our condensed consolidated financial statements and disclosures.

Description of Business, Basi_3

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2022
Accounting Policies [Abstract]
Schedule of Cash and Cash Equivalents and Restricted Cash	The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the condensed consolidated balance sheet to the total of the same such amounts shown in the condensed consolidated statement of cash flows: (in thousands) September 30, 2022 September 30, 2021 Cash and cash equivalents $ 237,676 $ 413,880 Non-current restricted cash 2,081 2,074 Total cash, cash equivalents and restricted $ 239,757 $ 415,954

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2022
Revenue from Contract with Customer [Abstract]
Summary of Changes in Balances of Contract Assets and Contract Liability	The following table presents changes during the nine months ended September 30, 2022 in the balances of contract assets, including receivables from collaborative partners, consulting and related technology transfer partners, and contract liabilities, including deferred revenue, as compared to what was disclosed in the Company’s Annual Report. (in thousands) Contract Assets BALANCE - December 31, 2021 $ 3,367 Additions for revenue recognized from billings 1,700 Deductions for cash collections ( 3,023 ) BALANCE – September 30, 2022 $ 2,044 (in thousands) Contract Liabilities BALANCE - December 31, 2021 $ 63,413 Additions for advanced billings 1,700 Reclassifications to accrued liabilities ( 9,572 ) Deductions for promised services provided in current period ( 45,706 ) BALANCE – September 30, 2022 $ 9,835
Schedule of Revenue	The following table summarizes the Company’s revenues for the periods indicated (in thousands). For the Three Months For the Nine Months (Dollars in thousands) 2022 2021 2022 2021 Vinbiocare $ 11,237 $ 600 $ 26,815 $ 600 Janssen 934 636 2,593 2,229 Ultragenyx 928 926 2,814 2,776 CureVac 225 241 673 713 Israel Ministry of Health — — 12,500 — Other 45 34 311 247 Total revenue $ 13,369 $ 2,437 $ 45,706 $ 6,565

Balance Sheet Details (Tables)

Balance Sheet Details (Tables)	9 Months Ended
	Sep. 30, 2022
Balance Sheet Related Disclosures [Abstract]
Summary of Components of Property and Equipment, Net	Property and equipment, net balances consisted of the following: (in thousands) September 30, 2022 December 31, 2021 Research equipment $ 8,584 $ 6,735 Computers and software 1,038 488 Office equipment and furniture 958 574 Leasehold improvements 2,486 44 Construction in progress 3,513 2,058 Total 16,579 9,899 Less accumulated depreciation and amortization ( 5,232 ) ( 4,256 ) Property and equipment, net $ 11,347 $ 5,643
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following: (in thousands) September 30, 2022 December 31, 2021 Accrued compensation $ 7,802 $ 3,578 Cystic Fibrosis Foundation liability (Note 9) — 2,777 Current portion of operating lease liability 3,783 1,537 Clinical accruals 2,026 8,675 Vinbiocare contractual liabilities 5,896 — Other accrued research and development expenses 6,022 6,956 Total $ 25,529 $ 23,523

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2022
Debt Disclosure [Abstract]
Schedule of Maturities of Long-term Debt	Principal payments, including the final payment due at repayment, on the long-term debt are as follows as of September 30, 2022: (in thousands) 2022 $ 3,000 2023 10,300 Total $ 13,300

Share-Based Compensation Expe_2

Share-Based Compensation Expense (Tables)	9 Months Ended
	Sep. 30, 2022
Share-Based Payment Arrangement [Abstract]
Schedule of Share-based Compensation Expenses	Share-based compensation expense included in the Company’s condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2022 and 2021 was as follows: For the Three Months For the Nine Months (in thousands) 2022 2021 2022 2021 Research and development $ 3,996 $ 3,304 $ 10,811 $ 10,132 General and administrative 5,440 3,566 13,270 11,265 Total $ 9,436 $ 6,870 $ 24,081 $ 21,397

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2022
Commitments and Contingencies Disclosure [Abstract]
Remaining Payments of Operating Lease Liability	As of September 30, 2022, the remaining payments of the operating lease liability were as follows: (in thousands) Remaining Lease Payments 2022 $ 1,338 2023 5,482 2024 5,646 2025 4,019 2026 3,603 Thereafter 23,282 Total remaining lease payments 43,370 Less: imputed interest ( 8,369 ) Total operating lease liabilities $ 35,001 Weighted-average remaining lease term 9.0 years Weighted-average discount rate 5.0 %

Description of Business, Basi_4

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies (Details Textual)	9 Months Ended
	Sep. 30, 2022 USD ($) Segment	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Nov. 07, 2020 SGD ($)
Summary Of Significant Accounting Policy [Line Items]
Investment in joint venture	$ 9,200,000
Upfront fee/consideration	9,200,000
Cash consideration paid for equity interest in joint venture	$ 0
Percentage of equity interest in joint venture	49%
Accumulated deficit	$ 455,488,000		$ 347,490,000
Cash and cash equivalents, including restricted cash	$ 239,757,000	$ 415,954,000	$ 372,569,000	$ 463,002,000
Number of operating segment for research and development | Segment	1
Dividends declared or paid	$ 0	$ 0
Singapore Economic Development Board [Member]
Summary Of Significant Accounting Policy [Line Items]
Term loan					$ 62,100,000
Vallon Pharmaceuticals, Inc. [Member]
Summary Of Significant Accounting Policy [Line Items]
Percentage of owned shares	7%
Axcelead, Inc [Member]
Summary Of Significant Accounting Policy [Line Items]
Equity method ownership percentage	49%
Arcalis, Inc [Member] | Maximum [Member]
Summary Of Significant Accounting Policy [Line Items]
Equity method ownership percentage	50%

Description of Business, Basi_5

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Cash and cash equivalents	$ 237,676	$ 370,492	$ 413,880
Non-current restricted cash	2,081	2,077	2,074
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	$ 239,757	$ 372,569	$ 415,954	$ 463,002

Revenue - Summary of Changes in

Revenue - Summary of Changes in Balances of Contract Assets and Contract Liability (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2022 USD ($)
Revenue from Contract with Customer [Abstract]
Contract Assets, Balance	$ 3,367
Contract Assets, Additions for revenue recognized from billings	1,700
Contract Assets, Deductions for cash collections	(3,023)
Contract Assets, Balance	2,044
Contract Liabilities, Balance	63,413
Contract Liabilities, Additions for advanced billings	1,700
Contract Liabilities, Reclassifications to accrued liabilities	(9,572)
Deductions for promised services provided in current period	(45,706)
Contract Liabilities, Balance	$ 9,835

Revenue - Summary of Revenues (

Revenue - Summary of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation Of Revenue [Line Items]
Total revenue	$ 13,369	$ 2,437	$ 45,706	$ 6,565
Vinbiocare [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	11,237	600	26,815	600
Janssen [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	934	636	2,593	2,229
Ultragenyx [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	928	926	2,814	2,776
CureVac [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	225	241	673	713
Israel Ministry of Health [Member]
Disaggregation Of Revenue [Line Items]
Total revenue			12,500
Other [Member]
Disaggregation Of Revenue [Line Items]
Total revenue	$ 45	$ 34	$ 311	$ 247

Revenue (Details Textual)

Revenue (Details Textual)	1 Months Ended	3 Months Ended		9 Months Ended	12 Months Ended
	Oct. 31, 2022	Sep. 30, 2022 USD ($) VaccineDose	Dec. 31, 2021 USD ($)	Sep. 30, 2022 USD ($) VaccineDose	Dec. 31, 2021 USD ($)	Nov. 09, 2022 USD ($)	Jan. 31, 2022 USD ($)	Oct. 31, 2020 USD ($)
Revenue [Line Items]
Deferred revenue		$ 9,835,000	$ 63,413,000	$ 9,835,000	$ 63,413,000
Revenue recognized				(45,706,000)
Israeli Ministry of Health ("MOH") [Member]
Revenue [Line Items]
Remaining performance obligation		$ 0		$ 0
Non-refundable payment received								$ 12,500,000
Number of reserved vaccine doses | VaccineDose		500,000		500,000
Subsequent Event | Janssen [Member]
Revenue [Line Items]
Notice period of termination	60 days
Study Support Agreement | ASC 606 [Member] | Vinbiocare [Member]
Revenue [Line Items]
Revenue recognized				$ 11,200,000
Study Support Agreement | Current | ASC 606 [Member] | Vinbiocare [Member]
Revenue [Line Items]
Accrued liabilities paid upon occurrence of specified events				5,900,000
Study Support Agreement | Non-current | ASC 606 [Member] | Vinbiocare [Member]
Revenue [Line Items]
Accrued liabilities paid upon occurrence of specified events				3,700,000
Vinbiocare Agreement [Member]
Revenue [Line Items]
Upfront payment received					40,000,000
Vinbiocare Agreement [Member] | ASC 606 [Member]
Revenue [Line Items]
Deferred revenue		$ 0	37,200,000	0	37,200,000
Remaining performance obligation		0		0
Research Collaboration And Exclusive License Agreement [Member] | ASC 606 [Member] | Janssen [Member]
Revenue [Line Items]
Deferred revenue		6,000,000	6,300,000	6,000,000	6,300,000
Remaining performance obligation		0		0
Notice period of termination	60 days
Preclinical milestone payment received			1,000,000
Research Collaboration And Exclusive License Agreement [Member] | ASC 606 [Member] | Ultragenyx [Member]
Revenue [Line Items]
Deferred revenue		2,800,000	5,500,000	2,800,000	5,500,000
Remaining performance obligation		0		0
Revenue recognition potential milestone revenue recognized				$ 138,000,000
Royalty payment term description				Ultragenyx will pay royalties as a single-digit percentage of net sales on a product-by-product and country-by-country basis during the applicable royalty term.
Revenue, practical expedient description				The Company recognizes the reimbursement of labor and expenses as costs are incurred and none of the development and commercialization milestones were included in the transaction price, as all milestone amounts were fully constrained.
Revenue recognition, reserve target exclusivity period				4 years
Adjustments to transaction price		0
mRNA Technology [Member] | ASC 606 [Member] | CureVac [Member]
Revenue [Line Items]
Deferred revenue		700,000	$ 1,400,000	$ 700,000	$ 1,400,000
Remaining performance obligation		0		$ 0
Revenue, practical expedient description				The Company recognizes the reimbursement of labor and expenses as costs are incurred and none of the development and commercialization milestones were included in the transaction price, as all milestone amounts were fully constrained
Development and option agreement date				2018-01
Adjustments to transaction price				$ 0
Upfront fee received				$ 5,000,000
Contractual term				10 months
Other Collaboration Agreements [Member] | Pharmaceutical Company [Member]
Revenue [Line Items]
Amount agreed to fund		25,000,000		$ 25,000,000			$ 25,000,000
Billing received amount from third party related to clinical trial		$ 4,900,000		$ 4,900,000
Other Collaboration Agreements [Member] | Subsequent Event | Pharmaceutical Company [Member]
Revenue [Line Items]
Billing received amount from third party related to clinical trial						$ 4,900,000

Grant Revenue (Details Textual)

Grant Revenue (Details Textual) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Aug. 31, 2022	Sep. 30, 2022
Grant Revenue [Abstract]
Grant revenue	$ 63.2
Remaining available funding net of revenue earned		$ 63.2

Balance Sheet Details - Summary

Balance Sheet Details - Summary of Components of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 16,579	$ 9,899
Less accumulated depreciation and amortization	(5,232)	(4,256)
Property and equipment, net	11,347	5,643
Research equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	8,584	6,735
Computer and software [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,038	488
Office equipment and furniture [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	958	574
Leasehold improvements [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	2,486	44
Construction in progress [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 3,513	$ 2,058

Balance Sheet Details (Details

Balance Sheet Details (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Balance Sheet Related Disclosures [Abstract]
Depreciation and amortization	$ 400	$ 300	$ 976	$ 883

Balance Sheet Details - Schedul

Balance Sheet Details - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Accrued Liabilities, Current [Abstract]
Accrued compensation	$ 7,802	$ 3,578
Cystic Fibrosis Foundation Liability (Note 9)		2,777
Current portion of operating lease liability	3,783	1,537
Clinical accruals	2,026	8,675
Vinbiocare contractual liabilities	5,896
Other accrued research and development expenses	6,022	6,956
Total	$ 25,529	$ 23,523

Debt (Details Textual)

Debt (Details Textual)

1 Months Ended

3 Months Ended

9 Months Ended

Oct. 30, 2019 USD ($)

Oct. 12, 2018 USD ($)

Apr. 30, 2022

Oct. 31, 2021

Sep. 30, 2022 USD ($)

Mar. 31, 2022 USD ($)

Sep. 30, 2021 USD ($)

Sep. 30, 2022 USD ($)

Sep. 30, 2021 USD ($)

Sep. 30, 2022 SGD ($)

Jan. 29, 2021 USD ($)

Jan. 29, 2021 SGD ($)

Nov. 07, 2020 SGD ($)

Debt Instrument [Line Items]

Long-term debt

$ 13,300,000

$ 13,300,000

Foreign currency transaction gain

1,862,000

$ 506,000

3,237,000

$ 923,000

Interest expense related to long-term debt

700,000

700,000

$ 2,100,000

2,000,000

Net increase in indebtedness

46,599,000

Loan and Security Agreement [Member] | Western Alliance Bank [Member] | Long-term Debt [Member]

Debt Instrument [Line Items]

Term loan

$ 15,000,000

Proceeds from long-term debt agreement

$ 10,000,000

Debt instrument, collateral

The Loan is collateralized by all of the assets of Arcturus Therapeutics, Inc., excluding intellectual property, which is subject to a negative pledge. The Loan contains customary conditions of borrowing, events of default and covenants, including covenants that restrict Arcturus Therapeutics, Inc.’s ability to dispose of assets, merge with or acquire other entities, incur indebtedness and make distributions to holders of its capital stock. In addition, Arcturus Therapeutics, Inc. is required to maintain at least 100% of its consolidated, unrestricted cash, or $15.0 million, whichever is lower, with the Bank.

Debt instrument, collateral amount

15,000,000

Net increase in indebtedness

$ 5,000,000

Loan maturity date

Oct. 30, 2023

Loan interest-only payment extended maturity date

Oct. 01, 2021

Extension to interest only period

3 months

6 months

Loan first principal payment extended maturity date

Aug. 01, 2022

May 01, 2022

Loan origination fee paid

54,000

Warrant fee payable

$ 525,000

Prepayment fee percentage

2%

Loan and Security Agreement [Member] | Western Alliance Bank [Member] | Long-term Debt [Member] | Minimum [Member]

Debt Instrument [Line Items]

Percentage required to be maintain in consolidated, unrestricted cash

100%

Interest of the prime rate plus

1.25%

Prepayment fee percentage

0.50%

Loan and Security Agreement [Member] | Western Alliance Bank [Member] | Long-term Debt [Member] | Maximum [Member]

Debt Instrument [Line Items]

Interest of the prime rate plus

2.75%

Prepayment fee percentage

2%

Singapore Economic Development Board [Member]

Debt Instrument [Line Items]

Term loan

$ 62,100,000

Term loan draw down

$ 46,600,000

$ 62,100,000

Potential principal repayment of loan

15,700,000

$ 15,700,000

$ 20,900,000

Loan accrues interest rate per annum, percentage

4.50%

Accrued interest added to principal debt balance

$ 1,900,000

Long-term debt

$ 47,800,000

$ 46,600,000

Foreign currency transaction gain

3,000,000

900,000

Interest expense related to long-term debt

$ 500,000

$ 500,000

$ 1,600,000

$ 1,400,000

Debt - Summary of Final Payment

Debt - Summary of Final Payment Due at Repayment (Details) $ in Thousands	Sep. 30, 2022 USD ($)
Debt Disclosure [Abstract]
2022	$ 3,000
2023	10,300
Total	$ 13,300

Stockholders' Equity (Details T

Stockholders' Equity (Details Textual) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Feb. 19, 2021	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Class Of Stock [Line Items]
Non-cash charge recorded in acquired in-process research and development expense					$ 5,000
Antidilutive securities excluded from computation of earnings per share		507,021	1,457,223	650,144	1,514,023
Alexion [Member]
Class Of Stock [Line Items]
Issuance of common stock	74,713
Common stock issued, value	$ 5,000
Non-cash charge recorded in acquired in-process research and development expense				$ 5,000

Share-Based Compensation Expe_3

Share-Based Compensation Expense (Details Textual) - shares	Sep. 30, 2022	Jun. 30, 2022	Apr. 30, 2022	Oct. 20, 2021	Oct. 15, 2021
2019 Omnibus Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation number of shares authorized		3,750,000
2019 Omnibus Equity Incentive Plan [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation number of shares authorized		8,750,000
2019 Omnibus Equity Incentive Plan [Member] | Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	3,490,857
2021 Inducement Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Reduction in number of common stock shares available for future issuance			130,000
2021 Inducement Equity Incentive Plan [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available		3,750,000		1,000,000	1,000,000
2021 Inducement Equity Incentive Plan [Member] | Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	70,400

Share-Based Compensation Expe_4

Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expenses	$ 9,436	$ 6,870	$ 24,081	$ 21,397
Research and Development [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expenses	3,996	3,304	10,811	10,132
General and Administrative [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expenses	$ 5,440	$ 3,566	$ 13,270	$ 11,265

Income Taxes (Details Textual)

Income Taxes (Details Textual) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income tax expense	$ 0	$ 0	$ 0	$ 0

Commitments and Contingencies_2

Commitments and Contingencies (Details Textual) $ in Millions

1 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

Oct. 02, 2020 SGD ($) Installment

Aug. 01, 2019 USD ($)

Jul. 12, 2019 USD ($)

Sep. 30, 2021 USD ($)

Feb. 28, 2021 USD ($)

Oct. 31, 2017 USD ($)

Sep. 30, 2022 USD ($)

Mar. 31, 2022 USD ($)

Sep. 30, 2021 USD ($)

Dec. 31, 2020 USD ($)

Sep. 30, 2022 USD ($)

Sep. 30, 2021 USD ($)

Dec. 31, 2021 USD ($)

Oct. 02, 2020 USD ($)

Mar. 04, 2020 SGD ($)

Mar. 04, 2020 USD ($)

Feb. 29, 2020

Commitment And Contingencies [Line Items]

Operating lease costs

$ 1,400,000

$ 500,000

$ 3,300,000

$ 1,400,000

October 2017 Lease Amendment [Member]

Commitment And Contingencies [Line Items]

Operating lease extended additional term

84 months

Lessee, operating lease, term of contract

4 months

Tenant improvement allowance

$ 74,000

Lessee, operating leases, option to extend

The lease may be extended for one five-year period at the then current market rate with annual escalations;

Security deposit

$ 96,000

February 2020 Lease Agreement [Member]

Commitment And Contingencies [Line Items]

Operating lease extended additional term

13 months

Lessee, operating leases, option to extend

the lease for one twelve-month period. In February 2021, the Company opted to extend the lease through March 2025 to coincide with the lease term of the Company’s headquarters

February 2021 Lease Agreement [Member]

Commitment And Contingencies [Line Items]

Lessee, operating leases, option to extend

the Company opted to extend the lease for an additional 12 months

Monthly base rent

$ 11,000

September 2021 Lease Agreement [Member]

Commitment And Contingencies [Line Items]

Operating lease extended additional term

10 years 8 months

10 years 8 months

10 years 8 months

Lessee, operating leases, option to extend

the Company will have the right to extend the term of the lease for an additional five-year period

Security deposit

$ 2,000,000

$ 2,000,000

$ 2,000,000

COVID-19 Vaccine Development | Grant 1

Commitment And Contingencies [Line Items]

Contra research and development expense recognized

1,300,000

Contra expense remaining amount included in accrued expenses

$ 0

$ 0

COVID-19 Vaccine Development | Grant 2

Commitment And Contingencies [Line Items]

Grant, number of installments | Installment

2

Received first installment

$ 3,600,000

$ 3,600,000

Underlying Agreement [Member] | Cystic Fibrosis Foundation [Member]

Commitment And Contingencies [Line Items]

Contra expense remaining amount included in accrued expenses

0

$ 2,800,000

Payments for matching funds for remaining budgeted costs

$ 5,000,000

Disbursed amount upon execution of amendment

4,000,000

Final payment of disbursement amount

3,000,000

Disbursement payment upon achievement of required manufacturing practices and IND application

2,300,000

Contra expense included in research and development expense

$ 500,000

$ 1,600,000

$ 2,700,000

$ 3,100,000

Underlying Agreement [Member] | Cystic Fibrosis Foundation [Member] | Disbursement Due January 2020 [Member]

Commitment And Contingencies [Line Items]

Disbursement amount payable upon achievement of project goal

2,000,000

Underlying Agreement [Member] | Cystic Fibrosis Foundation [Member] | Disbursement Due April 2020 [Member]

Commitment And Contingencies [Line Items]

Disbursement amount payable upon achievement of project goal

2,000,000

Underlying Agreement [Member] | Cystic Fibrosis Foundation [Member] | Disbursement Due July 2020 [Member]

Commitment And Contingencies [Line Items]

Disbursement amount payable upon achievement of project goal

2,000,000

Underlying Agreement [Member] | Cystic Fibrosis Foundation [Member] | Disbursement Due October 2020 [Member]

Commitment And Contingencies [Line Items]

Disbursement amount payable upon achievement of project goal

2,000,000

Underlying Agreement [Member] | LUNAR-CF [Member] | Cystic Fibrosis Foundation [Member]

Commitment And Contingencies [Line Items]

Payments for advance

$ 15,000,000

$ 3,200,000

Maximum [Member] | September 2021 Lease Agreement [Member]

Commitment And Contingencies [Line Items]

Monthly base rent

360,000,000

Minimum [Member] | September 2021 Lease Agreement [Member]

Commitment And Contingencies [Line Items]

Monthly base rent

$ 268,000,000

Singapore Economic Development Board [Member] | Maximum [Member] | COVID-19 Vaccine Development | Grant 1

Commitment And Contingencies [Line Items]

Grants Receivable

$ 14

$ 10,000,000

Singapore Economic Development Board [Member] | Maximum [Member] | COVID-19 Vaccine Development | Grant 2

Commitment And Contingencies [Line Items]

Grants Receivable

$ 9.3

$ 6,700,000

Commitments and Contingencies -

Commitments and Contingencies - Remaining Payments of Operating Lease Liability (Details) $ in Thousands	Sep. 30, 2022 USD ($)
Leases [Abstract]
2022	$ 1,338
2023	5,482
2024	5,646
2025	4,019
2026	3,603
Thereafter	23,282
Total remaining lease payments	43,370
Less: imputed interest	(8,369)
Total operating lease liabilities	$ 35,001
Weighted-average remaining lease term	9 years
Weighted-average discount rate	5%

Related Party Transactions - Eq

Related Party Transactions - Equity-Method Investment (Details Textual) - $ / shares	1 Months Ended
	May 31, 2022	Sep. 30, 2022	Feb. 28, 2021	Jun. 30, 2018
Vallon Pharmaceuticals, Inc. [Member]
Related Party Transaction [Line Items]
Percentage of owned shares		7%
ADAIR Technology [Member]
Related Party Transaction [Line Items]
Equity method ownership percentage				30%
ADAIR Technology [Member] | Vallon Pharmaceuticals, Inc. [Member]
Related Party Transaction [Line Items]
Exercise of warrants for shares of common stock	2,220,000
Number of shares owned			843,750
Percentage of owned shares			7%
Share price	$ 0.94
ADAIR Technology [Member] | Vallon Pharmaceuticals, Inc. [Member] | Private Placement [Member]
Related Party Transaction [Line Items]
Equity method investment, sale of common stock	3,700,000

Subsequent Events (Details Text

Subsequent Events (Details Textual) - Subsequent Event [Member] - USD ($) $ in Millions		1 Months Ended
	Nov. 01, 2022	Oct. 31, 2022
Seqirus, Inc [Member] | Research Collaboration And Exclusive License Agreement [Member]
Subsequent Event [Line Items]
Upfront payment to be received	$ 200
Seqirus, Inc [Member] | Research Collaboration And Exclusive License Agreement [Member] | Maximum [Member]
Subsequent Event [Line Items]
Eligible to receive development milestone payment	1,300
Eligible to receive commercial milestone payment	$ 3,000
Seqirus, Inc [Member] | Research Collaboration And Exclusive License Agreement [Member] | COVID-19 Vaccine [Member]
Subsequent Event [Line Items]
Net profits percentage	40%
Janssen [Member]
Subsequent Event [Line Items]
Notice period of termination		60 days