Protagonist Therapeutics (PTGX) 10-Q 2 Nov 23 2023 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2023	Oct. 27, 2023
Document And Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Entity File Number	001-37852
Entity Registrant Name	PROTAGONIST THERAPEUTICS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	98-0505495
Entity Address, Address Line One	7707 Gateway Boulevard, Suite 140
Entity Address, City or Town	Newark
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94560-1160
City Area Code	510
Local Phone Number	474-0170
Title of 12(b) Security	Common Stock
Trading Symbol	PTGX
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		57,678,122
Entity Central Index Key	0001377121
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 230,527,000	$ 125,744,000
Marketable securities	90,224,000	111,611,000
Receivable from collaboration partner		10,000
Prepaid expenses and other current assets	4,130,000	5,712,000
Total current assets	324,881,000	243,077,000
Marketable securities - noncurrent	1,985,000	0
Property and equipment, net	1,421,000	1,565,000
Restricted cash - noncurrent	225,000	225,000
Operating lease right-of-use asset	1,504,000	3,061,000
Total assets	330,016,000	247,928,000
Current liabilities:
Accounts payable	1,252,000	3,640,000
Payable to collaboration partner	3,000	69,000
Accrued expenses and other payables	24,809,000	24,955,000
Operating lease liability - current	1,803,000	2,515,000
Total current liabilities	27,867,000	31,179,000
Operating lease liability - noncurrent		1,141,000
Total liabilities	27,867,000	32,320,000
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.00001 par value, 10,000,000 shares authorized; no shares issued and outstanding
Common stock, $0.00001 par value, 90,000,000 shares authorized; 57,647,476 and 49,339,252 shares issued and outstanding as of September 30, 2023 and December 31, 2022, respectively	1,000
Additional paid-in capital	945,363,000	752,722,000
Accumulated other comprehensive loss	(170,000)	(359,000)
Accumulated deficit	(643,045,000)	(536,755,000)
Total stockholders' equity	302,149,000	215,608,000
Total liabilities and stockholders' equity	$ 330,016,000	$ 247,928,000

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
Condensed Consolidated Balance Sheets
Preferred stock, par value	$ 0.00001	$ 0.00001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.00001	$ 0.00001
Common stock, shares authorized	90,000,000	90,000,000
Common stock, shares issued	57,647,476	49,339,252
Common stock, shares outstanding	57,647,476	49,339,252

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Condensed Consolidated Statements of Operations
License and collaboration revenue	$ 0	$ 0	$ 0	$ 26,581
Revenue from Contract with Customer, Product and Service [Extensible List]	License and Collaboration Agreement	License and Collaboration Agreement	License and Collaboration Agreement	License and Collaboration Agreement
Operating expenses:
Research and development	$ 30,664	$ 25,402	$ 91,262	$ 96,331
General and administrative	7,662	6,901	25,439	25,107
Total operating expenses	38,326	32,303	116,701	121,438
Loss from operations	(38,326)	(32,303)	(116,701)	(94,857)
Interest income	4,252	1,157	10,656	1,809
Other expense, net	(31)	(86)	(245)	(151)
Net loss	$ (34,105)	$ (31,232)	$ (106,290)	$ (93,199)
Net loss per share, basic	$ (0.58)	$ (0.64)	$ (1.91)	$ (1.90)
Net loss per share, diluted	$ (0.58)	$ (0.64)	$ (1.91)	$ (1.90)
Weighted-average shares used to compute net loss per share, basic	59,182,899	49,107,639	55,542,543	48,971,329
Weighted-average shares used to compute net loss per share, diluted	59,182,899	49,107,639	55,542,543	48,971,329

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Condensed Consolidated Statements of Comprehensive Loss
Net loss	$ (34,105)	$ (31,232)	$ (106,290)	$ (93,199)
Other comprehensive loss:
(Loss) gain on translation of foreign operations		(79)	194	(193)
Unrealized gain (loss) on marketable securities	28	319	(5)	12
Comprehensive loss	$ (34,077)	$ (30,992)	$ (106,101)	$ (93,380)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholder's Equity - USD ($) $ in Thousands	Common Stock At-the-market offering	Common Stock Public offerings	Common Stock	Additional Paid-In Capital At-the-market offering	Additional Paid-In Capital Public offerings	Additional Paid-In Capital	Accumulated Other Comprehensive (Loss) Gain	Accumulated Deficit	At-the-market offering	Public offerings	Total
Balance, Beginning at Dec. 31, 2021						$ 709,682	$ (299)	$ (409,362)			$ 300,021
Balance, Beginning (in shares) at Dec. 31, 2021			47,838,330
Increase (Decrease) in Stockholders' Equity
Issuance of common stock, net of issuance costs				$ 14,553					$ 14,553
Issuance of common stock, net of issuance costs (in shares)	422,367
Issuance of common stock under equity incentive and employee stock purchase plans						3,895					3,895
Issuance of common stock under equity incentive and employee stock purchase plans (in shares)			545,443
Issuance of common stock upon exercise of Warrants (in shares)			399,997
Shares withheld for net settlement of tax withholding upon vesting of restricted stock units						(188)					(188)
Shares withheld for net settlement of tax withholding upon vesting of restricted stock units (in shares)			(7,726)
Stock-based compensation expense						18,690					18,690
Issuance costs related to prior period common stock offering						25					25
Other comprehensive gain (loss)							(181)				(181)
Net loss								(93,199)			(93,199)
Balance, Ending at Sep. 30, 2022						746,657	(480)	(502,561)			243,616
Balance, Ending (in shares) at Sep. 30, 2022			49,198,411
Balance, Beginning at Dec. 31, 2021						709,682	(299)	(409,362)			300,021
Balance, Beginning (in shares) at Dec. 31, 2021			47,838,330
Balance, Ending at Dec. 31, 2022						752,722	(359)	(536,755)			$ 215,608
Balance, Ending (in shares) at Dec. 31, 2022			49,339,252								49,339,252
Balance, Beginning at Jun. 30, 2022						740,027	(720)	(471,329)			$ 267,978
Balance, Beginning (in shares) at Jun. 30, 2022			48,683,931
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under equity incentive and employee stock purchase plans						680					680
Issuance of common stock under equity incentive and employee stock purchase plans (in shares)			114,483
Issuance of common stock upon exercise of Warrants (in shares)			399,997
Stock-based compensation expense						5,950					5,950
Other comprehensive gain (loss)							240				240
Net loss								(31,232)			(31,232)
Balance, Ending at Sep. 30, 2022						746,657	(480)	(502,561)			243,616
Balance, Ending (in shares) at Sep. 30, 2022			49,198,411
Balance, Beginning at Dec. 31, 2022						752,722	(359)	(536,755)			$ 215,608
Balance, Beginning (in shares) at Dec. 31, 2022			49,339,252								49,339,252
Increase (Decrease) in Stockholders' Equity
Exercise of Warrants in exchange for issuance of Pre-funded Warrants						33,813					$ 33,813
Issuance of common stock, net of issuance costs	$ 1			$ 24,301	$ 107,790				$ 24,302	$ 107,790
Issuance of common stock, net of issuance costs (in shares)	1,749,199	5,750,000
Issuance of common stock under equity incentive and employee stock purchase plans						4,255					4,255
Issuance of common stock under equity incentive and employee stock purchase plans (in shares)			796,240
Issuance of common stock upon exercise of Warrants						559					559
Issuance of common stock upon exercise of Warrants (in shares)			44,748
Shares withheld for net settlement of tax withholding upon vesting of restricted stock units						(769)					(769)
Shares withheld for net settlement of tax withholding upon vesting of restricted stock units (in shares)			(31,963)
Stock-based compensation expense						22,692					22,692
Other comprehensive gain (loss)							189				189
Net loss								(106,290)			(106,290)
Balance, Ending at Sep. 30, 2023			$ 1			945,363	(170)	(643,045)			$ 302,149
Balance, Ending (in shares) at Sep. 30, 2023			57,647,476								57,647,476
Balance, Beginning at Jun. 30, 2023			$ 1			903,205	(198)	(608,940)			$ 294,068
Balance, Beginning (in shares) at Jun. 30, 2023			57,494,185
Increase (Decrease) in Stockholders' Equity
Exercise of Warrants in exchange for issuance of Pre-funded Warrants						33,813					33,813
Issuance of common stock under equity incentive and employee stock purchase plans						1,021					1,021
Issuance of common stock under equity incentive and employee stock purchase plans (in shares)			108,543
Issuance of common stock upon exercise of Warrants						559					559
Issuance of common stock upon exercise of Warrants (in shares)			44,748
Stock-based compensation expense						6,765					6,765
Other comprehensive gain (loss)							28				28
Net loss								(34,105)			(34,105)
Balance, Ending at Sep. 30, 2023			$ 1			$ 945,363	$ (170)	$ (643,045)			$ 302,149
Balance, Ending (in shares) at Sep. 30, 2023			57,647,476								57,647,476

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash Flows from Operating Activities
Net loss	$ (106,290)	$ (93,199)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	22,692	18,690
Operating lease right-of-use asset amortization	1,751	1,751
(Accretion) Amortization of discount/premium on marketable securities	(3,221)	365
Depreciation	729	778
Other	194
Changes in operating assets and liabilities:
Research and development tax incentive receivable		2,719
Receivable from collaboration partner	10	1,441
Prepaid expenses and other assets	1,582	413
Accounts payable	(2,271)	3,121
Payable to collaboration partner	(66)	(867)
Accrued expenses and other payables	(259)	(8,127)
Deferred revenue		(1,601)
Operating lease liability	(2,047)	(1,986)
Net cash used in operating activities	(87,196)	(76,502)
Cash Flows from Investing Activities
Purchase of marketable securities	(93,077)	(134,279)
Proceeds from maturities of marketable securities	115,696	222,537
Purchases of property and equipment	(590)	(725)
Net cash provided by investing activities	22,029	87,533
Cash Flows from Financing Activities
Proceeds from public offering of common stock, net of issuance costs	107,790
Proceeds from at-the-market offering, net of issuance costs	24,302	14,553
Proceeds from exercise of Warrants in exchange for issuance of Pre-funded Warrants	33,813
Proceeds from issuance of common stock upon exercise of Warrants	559
Proceeds from issuance of common stock upon exercise of stock options and purchases under employee stock purchase plan	4,255	3,895
Tax withholding payments related to net settlement of restricted stock units	(769)	(188)
Issuance costs related to prior period common stock offering		25
Net cash provided by financing activities	169,950	18,285
Effect of exchange rate changes on cash, cash equivalents and restricted cash		(165)
Net increase in cash, cash equivalents and restricted cash	104,783	29,151
Cash, cash equivalents and restricted cash, beginning of period	125,969	123,890
Cash, cash equivalents and restricted cash, end of period	230,752	153,041
Supplemental Disclosure of Non-Cash Financing and Investing Information:
Purchases of property and equipment in accounts payable and accrued liabilities	$ 3	$ 61

Organization and Description of

Organization and Description of Business	9 Months Ended
	Sep. 30, 2023
Organization and Description of Business
Organization and Description of Business	PROTAGONIST THERAPEUTICS, INC. Notes to Unaudited Condensed Consolidated Financial Statements Note 1. Protagonist Therapeutics, Inc. (the “Company”) is headquartered in Newark, California. The Company is a biopharmaceutical company with peptide-based new chemical entities rusfertide and JNJ-2113 (formerly PN-235) in advanced stages of clinical development, both derived from the Company’s proprietary technology platform. The Company’s Operating segments are components of an enterprise for which separate financial information is available and is evaluated regularly by the Chief Executive Officer, the Company’s chief operating decision maker, in deciding how to allocate resources and assessing performance. Liquidity As of September 30, 2023, the Company had cash, cash equivalents and marketable securities of $322.7 million. The Company has incurred net losses from operations since inception and had an accumulated deficit of $643.0 million as of September 30, 2023. The Company’s ultimate success depends upon the outcome of its research and development and collaboration activities. The Company expects to incur additional losses in the future and anticipates the need to raise additional capital to continue to execute its long-range business plan. Since the Company’s initial public offering in August 2016, it has financed its operations primarily through proceeds from offerings of common stock and payments received under license and collaboration agreements. Risks and Uncertainties The Company is currently operating in a period of economic uncertainty and capital markets disruption, which has been impacted by the direct and indirect effects of the COVID-19 pandemic (“COVID-19”), domestic and global monetary and fiscal policy, geopolitical instability, including ongoing military conflicts between Russia and Ukraine and in Israel and surrounding areas, rising tensions between China and Taiwan, a recessionary environment, historically high domestic and global inflation, the potential impact of a U.S. government shutdown, and instability in banks and other financial institutions. The Company has experienced delays in its existing and planned clinical trials due to worldwide impacts related to COVID-19, and its future results of operations and liquidity could be adversely impacted by outbreaks of disease, epidemics and pandemics, including further delays in existing and planned clinical trials, difficulty in recruiting patients for these clinical trials, delays in manufacturing and collaboration activities and supply chain disruptions. The conflict in Ukraine has exacerbated market disruptions, including significant volatility in commodity prices as well as supply chain interruptions, and has contributed to record inflation globally. The U.S. Federal Reserve and other central banks may be unable to contain inflation through more restrictive monetary policy and inflation may increase or continue for a prolonged period of time. Inflationary factors, such as increases in the cost of clinical supplies, interest rates, overhead costs and transportation costs may adversely affect the Company’s operating results. In addition, the failure of Silicon Valley Bank and other regional banks in the United States during the first half of 2023 has given rise to uncertainty in the security of amounts in deposit accounts uninsured by the Federal Deposit Insurance Corporation. The Company continues to monitor these events and the potential impact on its business. Although the Company does not believe that inflation has had a material impact on its financial position or results of operations to date, it may be adversely affected in the future due to global monetary and fiscal policy, macroeconomic factors, supply chain constraints, the ongoing conflicts between Russia and Ukraine and in Israel and surrounding areas and other factors, and such factors may lead to increases in the cost of manufacturing for and delays in the initiation of studies in the Company’s product candidates.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2023
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	Note 2. Basis of Presentation and Consolidation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP have been condensed or omitted, and accordingly the condensed consolidated balance sheet as of September 30, 2023 has been derived from the Company’s unaudited consolidated financial statements at that date but does not include all of the information required by GAAP for complete consolidated financial statements. These unaudited interim condensed consolidated financial statements have been prepared on the same basis as the Company’s annual consolidated financial statements and, in the opinion of management, reflect all adjustments (consisting of normal recurring adjustments) that are necessary for a fair presentation of the Company’s condensed consolidated financial statements. The results of operations for the three and nine months ended September 30, 2023 are not necessarily indicative of the results to be expected for the year ending December 31, 2023 or for any future period. Effective January 1, 2023, the financial statements of Protagonist Australia use the U.S. dollar as the functional currency due to the expected nature of the ongoing operations of this subsidiary. The cumulative translation adjustment as of January 1, 2023 related to this subsidiary was not material. Prior to January 1, 2023, the financial statements of Protagonist Australia used the Australian dollar as the functional currency since the majority of expense transactions occurred in such currency. Foreign currency translation gains and losses are reported as a component of stockholders’ equity in accumulated other comprehensive loss on the condensed consolidated balance sheets. The accompanying unaudited condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto for the year ended December 31, 2022 included in the Company’s Annual Report on Form 10-K, filed with the SEC on March 15, 2023. Principles of Consolidation The accompanying unaudited interim condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiary. All intercompany transactions and balances have been eliminated upon consolidation. Use of Estimates The preparation of the condensed consolidated financial statements in conformity with GAAP requires management to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities and disclosure of contingent liabilities as of the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, accruals for research and development activities, stock-based compensation, income taxes, marketable securities and leases. Estimates related to revenue recognition include actual costs incurred versus total estimated costs of the Company’s deliverables to determine percentage of completion in addition to the application and estimates of potential revenue constraints in the determination of the transaction price under its license and collaboration agreements. Management bases these estimates on historical and anticipated results, trends, and various other assumptions that the Company believes are reasonable under the circumstances, including assumptions as to forecasted amounts and future events. Actual results could differ materially from these estimates. There has been uncertainty and disruption in the global economy and financial markets due to a number of factors, including the direct and indirect effects of COVID-19, geopolitical instability, inflationary pressures and domestic and global monetary and fiscal policy. The Company has taken into consideration any known impacts in its accounting estimates to date and is not aware of any additional specific events or circumstances that would require any additional updates to its estimates or judgments or a revision of the carrying value of its assets or liabilities as of the issuance of this report. These estimates may change as new events occur and additional information is obtained. Actual results could differ materially from these estimates under different assumptions or conditions. Cash as Reported in Condensed Consolidated Statements of Cash Flows Cash as reported in the condensed consolidated statements of cash flows includes the aggregate amounts of cash and cash equivalents and the restricted cash as presented on the condensed consolidated balance sheets. Cash as reported in the condensed consolidated statements of cash flows consists of (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ 2023 2022 Cash and cash equivalents ​ $ 230,527 ​ $ 152,816 Restricted cash – noncurrent ​ 225 ​ 225 Total cash reported on condensed consolidated statements of cash flows ​ $ 230,752 ​ $ 153,041 ​ Investment Impairment ​ As of each reporting date, the Company assesses each of its investments in available-for-sale debt securities whose fair value is below its cost basis to determine if the investment’s impairment is due to credit-related factors or noncredit-related factors. Factors considered in determining whether an impairment is credit-related include the extent to which the investment’s fair value is less than its cost basis, declines in published credit ratings, issuer default on interest or principal payments, and declines in the financial condition and near-term prospects of the issuer. Credit-related impairments on available-for-sale debt securities are recognized as an allowance for credit losses with a corresponding adjustment to other income (expense), net. The portion of the impairment that is not credit-related is recorded as a reduction of other comprehensive income (loss), net of applicable taxes. ​ Pursuant to Accounting Standard Update (“ASU”) 2016-13, Financial Instruments - Credit Losses (Topic 326) ​ Stock-Based Compensation Expense ​ The Company measures its stock-based awards made to its equity plan participants based on the estimated fair values of the awards as of the grant date. For stock option awards, the Company uses the Black-Scholes option-pricing model to estimate fair values. For restricted stock unit awards, the estimated fair value is generally the fair market value of the underlying stock on the grant date. Stock-based compensation expense is recognized over the requisite service period and is based on the value of the portion of stock-based payment awards that is ultimately expected to vest. The Company recognizes forfeitures of stock-based awards as they occur. ​ The Company has granted performance share units (“PSUs”) to certain executives of the Company. Stock-based compensation expense associated with PSUs is based on the fair value of the Company’s common stock on the grant date, which equals the closing price of the Company’s common stock on the grant date. The Company recognizes compensation expense over the vesting periods of the awards that are ultimately expected to vest when the achievement of the related performance obligation becomes probable. ​ Total stock-based compensation expense was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ September 30, ​ September 30, ​ 2023 2022 2023 2022 Research and development ​ $ 3,780 ​ $ 3,858 ​ $ 13,171 ​ $ 11,290 General and administrative ​ 2,985 ​ 2,092 ​ 9,521 ​ 7,400 Total stock-based compensation expense ​ $ 6,765 ​ $ 5,950 ​ $ 22,692 ​ $ 18,690 ​ Significant Accounting Policies ​ Other than the change in Protagonist Australia functional currency from the Australian dollar to the U.S. dollar effective January 1, 2023 and the investment impairment policy, as discussed above, there have been no material changes to the Company’s significant accounting policies during the three and nine months ended September 30, 2023 as compared to those disclosed in Note 2. Summary of Significant Accounting Policies included in our Annual Report on Form 10-K for the year ended December 31, 2022. ​ Recently Adopted Accounting Pronouncements In June 2016, the Financial Accounting Standard Board (“FASB”) issued ASU 2016-13. The guidance requires measurement and recognition of expected credit losses for financial assets at the time financial assets are initially recognized in the financial statements. The measurement of expected credit losses is based on historical credit loss information as well as current and future economic factors. ASU 2016-13 also eliminates the concept of “other-than-temporary” impairment when evaluating available-for-sale debt securities and instead focuses on determining whether any impairment is a result of credit loss or other factors. In November 2019, the FASB issued ASU 2019-10, Financial Instruments – Credit Losses (Topic 326): Effective Dates

License and Collaboration Agree

License and Collaboration Agreement	9 Months Ended
	Sep. 30, 2023
License and Collaboration Agreement..
License and Collaboration Agreement
License and Collaboration Agreement	Note 3. License and Collaboration Agreement Agreement Terms On July 27, 2021, the Company entered into an Amended and Restated License and Collaboration Agreement (the “Restated Agreement”) with Janssen Biotech, Inc., a Pennsylvania corporation (“Janssen”), which amended and restated the License and Collaboration Agreement, effective July 13, 2017, by and between the Company and Janssen (the “Original Agreement”), as amended by the first amendment, effective May 7, 2019 (the “First Amendment”). Prior to January 1, 2023, Janssen was a related party to the Company as Johnson & Johnson Innovation - JJDC, Inc. was a significant (greater than 5%) stockholder of the Company, and both companies are subsidiaries of Johnson & Johnson. Upon the effectiveness of the Original Agreement, the Company received a non-refundable, upfront cash payment of $50.0 million from Janssen. Upon the effectiveness of the First Amendment, the Company received a $25.0 million payment from Janssen in 2019. The Company received a $5.0 million payment triggered by the successful nomination of a second-generation oral Interleukin (“IL”)-23 receptor antagonist development compound (“second-generation compound”) during the first quarter of 2020 and received a $7.5 million payment triggered by the completion of data collection activities for the first Phase 1 clinical trial of a second-generation compound during the fourth quarter of 2021. The Company received a $25.0 million milestone payment in connection with the dosing of the third patient in the first Phase 2 clinical trial for a second-generation compound during the second quarter of 2022. The Restated Agreement relates to the development, manufacture and commercialization of oral IL-23 receptor antagonist drug candidates. The candidates nominated for initial development pursuant to the Restated Agreement included PTG-200 (JNJ-67864238), PN-232 (JNJ-75105186) and JNJ-2113 (JNJ-77242113) (formerly PN-235). PTG-200 is an oral IL-23 receptor antagonist that was in Phase 2a development for the treatment of Crohn’s disease (“CD”). During the fourth quarter of 2021, following a pre-specified interim analysis criteria, a portfolio decision was made by Janssen to stop further development of both PTG-200 and PN-232 in favor of advancing JNJ-2113, based on its superior potency and overall pharmacokinetic and pharmacodynamic profile. Janssen is primarily responsible for the conduct of all future trials, including anticipated Phase 2 and Phase 3 trials, and the Company is primarily responsible for the conduct of the second-generation Phase 1 trials. ​ The Restated Agreement enables Janssen to develop collaboration compounds for multiple indications. Under the Restated Agreement, Janssen is required to use commercially reasonable efforts to develop at least one collaboration compound for at least two indications. Upcoming potential development milestones for second-generation compounds include: ● $50.0 million upon the dosing of the third patient in a Phase 3 clinical trial for a second-generation compound for any indication; ● $115.0 million upon a Phase 3 clinical trial for a second-generation compound for any indication meeting its primary clinical endpoint; ● $35.0 million upon the filing of a New Drug Application (“NDA”) for a second-generation compound with the U.S. Food and Drug Administration (the “FDA”); ● $50.0 million upon FDA approval of an NDA for a second-generation compound; ● $10.0 million upon the dosing of the third patient in the first Phase 2 clinical trial for any second-generation compound for a second indication (i.e., an indication different than the indication which triggered the $25.0 million milestone received during the second quarter of 2022 described above); and ● $15.0 million upon the dosing of the third patient in a Phase 3 clinical trial for a second-generation compound for a second indication. Pursuant to the Restated Agreement, the Company remains eligible to receive tiered royalties on net product sales at percentages ranging from six percent to ten percent. The sales milestone payments in the Original Agreement also remain the same in the Restated Agreement. Pursuant to both the Original and Restated Agreements, payments to the Company for research and development services are generally billed and collected as services are performed or assets are delivered, including research activities and Phase 1 and Phase 2 development activities. Janssen bills the Company for its share of the PTG-200 Phase 2a development costs as expenses are incurred by Janssen. Milestone payments are received after the related milestones are achieved. Janssen retains exclusive, worldwide rights to develop and commercialize IL-23 receptor antagonist compounds derived from the research collaboration conducted under the Original Agreement, or Janssen’s further research under the Restated Agreement. Any further research and development will be conducted by Janssen. The Company will have the right to co-detail (for CD and ulcerative colitis indications) up to two of the IL-23 receptor antagonist compounds under the collaboration in the U.S. market. The Restated Agreement remains in effect until the royalty obligations cease following patent and regulatory expiry, unless terminated earlier. Upon a termination of the Restated Agreement, all rights revert back to the Company, and in certain circumstances, if such termination occurs during ongoing clinical trials, Janssen would, if requested, provide certain financial and operational support to the Company for the completion of such trials. Revenue Recognition The Restated Agreement contains a single performance obligation for the development license; Phase 1 development services for PTG-200, PN-232 and JNJ-2113 (formerly PN-235); the Company’s services associated with Phase 2a development for PTG-200 in CD; the initial year of second-generation compound research services; and all other such services that the Company may perform at the request of Janssen to support the development of PTG-200 through Phase 2a and PN-232 and JNJ-2113 through Phase 1. Under the Restated Agreement, development services performed by the Company for PTG-200 beyond Phase 2a and PN-232 and JNJ-2113 beyond Phase 1 are no longer required. The contract duration is defined as the period in which parties to the contract have present enforceable rights and obligations. For revenue recognition purposes, the duration of the Restated Agreement for the identified single initial performance obligation began on the Original Agreement’s effective date of July 13, 2017 and ended upon the completion of Phase 1 clinical trials for PN-232 and JNJ-2113. Final activities related to these trials were completed as of June 30, 2022. No license and collaboration revenue was recognized for the three and nine months ended September 30, 2023 because the Company completed its performance obligation under the collaboration as of June 30, 2022. For the three and nine months ended September 30, 2022, the Company recognized license and collaboration revenue of zero and $26.6 million, respectively. License and collaboration revenue for the nine months ended September 30, 2022 was primarily related to the transaction price recognized under the Restated Agreement based on proportional performance. The following tables present changes in the Company’s contract assets and liabilities during the periods presented (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ ​ ​ ​ ​ Balance at ​ ​ Beginning of ​ ​ ​ ​ ​ End of Nine Months Ended September 30, 2023 Period ​ Additions Deductions Period Contract assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Receivable from collaboration partner ​ $ 10 ​ $ 41 ​ ​ (51) ​ $ — Contract liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Payable to collaboration partner ​ $ 69 ​ $ 11 ​ ​ (77) ​ $ 3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ ​ ​ ​ ​ ​ ​ Balance at ​ ​ Beginning of ​ ​ ​ ​ ​ End of Nine Months Ended September 30, 2022 Period ​ Additions Deductions Period Contract assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Receivable from collaboration partner ​ $ 1,566 ​ $ 25,165 ​ $ (26,606) ​ $ 125 Contract liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred revenue ​ $ 1,601 ​ $ 25,757 ​ $ (27,358) ​ $ — Payable to collaboration partner ​ $ 899 ​ $ 52 ​ $ (919) ​ $ 32 ​ During the three and nine months ended September 30, 2022, the Company recognized revenue of zero and $0.9 million from amounts included in the deferred revenue contract liability balance at the beginning of each period. None of the costs to obtain or fulfill the contract were capitalized.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2023
Fair Value Measurements
Fair Value Measurements	Note 4. Fair Value Measurements Financial assets and liabilities are recorded at fair value. The accounting guidance for fair value provides a framework for measuring fair value, clarifies the definition of fair value and expands disclosures regarding fair value measurements. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. The accounting guidance establishes a three-tiered hierarchy, which prioritizes the inputs used in the valuation methodologies in measuring fair value as follows: Level 1 Level 2— Level 3 In determining fair value, the Company utilizes quoted market prices, broker or dealer quotations, or valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible and considers counterparty credit risk in its assessment of fair value. The following tables present the fair value of the Company’s financial assets determined using the inputs defined above (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 ​ Level 1 Level 2 Level 3 Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 70,470 ​ $ — ​ $ — $ 70,470 Certificates of deposit ​ — ​ ​ 4,799 ​ — 4,799 Commercial paper ​ — ​ ​ 132,226 ​ — 132,226 Corporate debt securities ​ ​ — ​ ​ 1,980 ​ ​ — ​ ​ 1,980 U.S. Treasury and agency securities ​ ​ — ​ ​ 108,786 ​ ​ — ​ ​ 108,786 Total financial assets ​ $ 70,470 ​ $ 247,791 $ — $ 318,261 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ Level 1 Level 2 Level 3 Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 54,292 ​ $ — ​ $ — $ 54,292 Commercial paper ​ — ​ 110,227 ​ — 110,227 Corporate debt securities ​ — ​ 10,741 — 10,741 U.S. Treasury and agency securities ​ ​ ​ ​ ​ 57,242 ​ ​ — 57,242 Total financial assets ​ $ 54,292 ​ $ 178,210 $ — $ 232,502 ​ The Company’s certificates of deposit, commercial paper, corporate debt securities, and U.S. Treasury and agency securities, including U.S. Treasury bills, are classified as Level 2 as they were valued based upon quoted market prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active and model-based valuation techniques, for which all significant inputs are observable in the market or can be corroborated by observable market data for substantially the full term of the assets. The carrying amount of the Company’s remaining financial assets and liabilities, including cash, receivables and payables, approximates their fair value due to their short-term nature.

Cash Equivalents and Marketable

Cash Equivalents and Marketable Securities	9 Months Ended
	Sep. 30, 2023
Cash Equivalents and Marketable Securities
Cash Equivalents and Marketable Securities	Note 5. Cash Equivalents and Marketable Securities ​ Cash equivalents and marketable securities consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 ​ ​ Amortized ​ Gross Unrealized ​ ​ Cost Gains Losses Fair Value Money market funds ​ $ 70,470 ​ $ — ​ $ — ​ $ 70,470 Certificates of deposit ​ ​ 4,798 ​ ​ 1 ​ ​ — ​ 4,799 Commercial paper ​ 132,275 ​ ​ — ​ ​ (49) ​ 132,226 Corporate debt securities ​ ​ 1,982 ​ ​ — ​ ​ (2) ​ ​ 1,980 U.S. Treasury and agency securities ​ ​ 108,794 ​ ​ 9 ​ ​ (17) ​ ​ 108,786 Total cash equivalents and marketable securities ​ $ 318,319 ​ $ 10 $ (68) ​ $ 318,261 Classified as: ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ ​ ​ ​ ​ ​ ​ $ 226,052 Marketable securities ​ ​ ​ ​ ​ ​ ​ 90,224 Marketable securities - noncurrent ​ ​ ​ ​ ​ ​ ​ 1,985 Total cash equivalents and marketable securities ​ ​ ​ ​ ​ ​ ​ $ 318,261 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ Amortized ​ Gross Unrealized ​ ​ Cost Gains Losses Fair Value Money market funds ​ $ 54,292 ​ $ — $ — ​ $ 54,292 Commercial paper ​ 110,257 ​ — (30) ​ 110,227 Corporate debt securities ​ 10,756 ​ — (15) ​ 10,741 U.S. Treasury and agency securities ​ ​ 57,251 ​ ​ 27 ​ ​ (36) ​ ​ 57,242 Total cash equivalents and marketable securities ​ $ 232,556 ​ $ 27 $ (81) ​ $ 232,502 Classified as: ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ ​ ​ ​ ​ ​ ​ $ 120,891 Marketable securities ​ ​ ​ ​ ​ ​ ​ 111,611 Total cash equivalents and marketable securities ​ ​ ​ ​ ​ ​ ​ $ 232,502 ​ Marketable securities of $90.2 million and $111.6 million held at September 30, 2023 and December 31, 2022, respectively, had contractual maturities of less than one year. Marketable securities – noncurrent of $2.0 million held at September 30, 2023 had contractual maturities of at least one year but less than two years. The Company did not hold any marketable securities – noncurrent at December 31, 2022. The Company does not intend to sell its securities that are in an unrealized loss position, and it is not more likely than not that the Company will be required to sell its securities before recovery of their amortized cost basis, which may be at maturity. There were no material realized gains or realized losses on marketable securities for the periods presented. The Company evaluated securities with unrealized losses to determine whether such losses, if any, are due to credit-related factors and determined that there were no credit-related losses to be recognized as of September 30, 2023.

Balance Sheet Components

Balance Sheet Components	9 Months Ended
	Sep. 30, 2023
Balance Sheet Components
Balance Sheet Components	Note 6. Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2023 ​ 2022 Prepaid insurance ​ $ 1,871 ​ $ 1,417 Prepaid clinical and research related expenses ​ ​ 578 ​ ​ 2,746 Prepaid licenses ​ ​ 410 ​ ​ 489 Other prepaid expenses ​ 1,206 ​ 1,018 Other receivable ​ ​ 65 ​ ​ 42 Prepaid expenses and other current assets ​ $ 4,130 ​ $ 5,712 ​ Property and Equipment, Net Property and equipment, net consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2023 ​ 2022 Laboratory equipment ​ $ 5,281 ​ $ 4,817 Furniture and computer equipment ​ 1,123 ​ 1,089 Leasehold improvements ​ 963 ​ 913 Total property and equipment ​ 7,367 ​ 6,819 Accumulated depreciation ​ (5,946) ​ (5,254) Property and equipment, net ​ $ 1,421 ​ $ 1,565 ​ ​ Accrued Expenses and Other Payables Accrued expenses and other payables consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2023 ​ 2022 Accrued clinical and research related expenses ​ $ 19,666 ​ $ 19,109 Accrued employee related expenses ​ 4,528 ​ 4,967 Accrued professional service fees ​ ​ 471 ​ ​ 464 Other ​ 144 ​ 415 Total accrued expenses and other payables ​ $ 24,809 ​ $ 24,955 ​

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2023
Stockholders' Equity
Stockholders' Equity	Note 7. Stockholders’ Equity In April 2023, the Company completed an underwritten public offering of 5,000,000 shares of its common stock at a public offering price of $20.00 per share and issued an additional 750,000 shares of common stock at a price of $20.00 per share following the underwriters’ exercise of their option to purchase additional shares. Net proceeds, after deducting underwriting commissions and offering costs paid by the Company, were approximately $107.8 million. ​ In August 2022, the Company entered into an Open Market Sale Agreement SM (the “Sales Agreement”), pursuant to which the Company may offer and sell up to $100.0 million shares of common stock from time to time in “at-the-market” offerings (the “2022 ATM Facility”). There were no sales of the Company’s common stock under the 2022 ATM Facility during the year ended December 31, 2022. During the three months ended March 31, 2023, the Company sold 1,749,199 shares of its common stock under the 2022 ATM Facility for net proceeds of $24.3 million, after deducting issuance costs. There were no sales of the Company’s common stock under the 2022 ATM Facility during the three months ended June 30, 2023 and September 30, 2023. ​ In November 2019, the Company entered into an Open Market Sale Agreement (the “Prior Sales Agreement”), pursuant to which the Company could offer and sell up to $75.0 million of shares of common stock from time to time in “at-the-market” offerings (the “2019 ATM Facility”). During the year ended December 31, 2022, the Company sold 422,367 shares of its common stock under the 2019 ATM Facility for net proceeds of $14.6 million, after deducting issuance costs. The Prior Sales Agreement was terminated in connection with and replaced by the Sales Agreement in August 2022. ​ In August 2018, the Company entered into a Securities Purchase Agreement with certain accredited investors (each, an “Investor” and, collectively, the “Investors”), pursuant to which the Company sold an aggregate of 2,750,000 shares of its common stock at a price of $8.00 per share, for aggregate net proceeds of $21.7 million, after deducting offering expenses payable by the Company. In a concurrent private placement, the Company issued the Investors warrants to purchase an aggregate of 2,750,000 shares of its common stock (each, a “Warrant” and, collectively, the “Warrants”). Each Warrant was exercisable from August 8, 2018 through August 8, 2023. Warrants to purchase 1,375,000 shares of the Company’s common stock had an exercise price of $10.00 per share and Warrants to purchase 1,375,000 shares of the Company’s common stock had an exercise price of $15.00 per share. The exercise price and number of shares of common stock issuable upon the exercise of the Warrants (the “Warrant Shares”) were subject to adjustment in the event of any stock dividends and splits, reverse stock split, recapitalization, reorganization or similar transaction, as described in the Warrants. Under certain circumstances, the Warrants were exercisable on a “cashless” basis. In connection with the issuance and sale of the common stock and Warrants, the Company granted the Investors certain registration rights with respect to the Warrants and the Warrant Shares. The common stock and Warrants were classified as equity in accordance with Accounting Standards Codification Topic 480 , Distinguishing Liabilities from Equity In August 2023, prior to the expiration of the Warrants, the Company entered into certain agreements with the Investors and their affiliates under which the Company agreed to allow the Warrants to be exercised in exchange for pre-funded warrants representing the same number of Warrant Shares underlying the Warrants with an exercise price of $0.001 per share (the “Pre-Funded Warrants”). Subsequent to the execution of the agreements and prior to the expiration of the Warrants, all outstanding Warrants were exercised for gross proceeds of $34.4 million in exchange for 44,748 shares of the Company’s common stock and Pre-Funded Warrants to purchase 2,705,252 shares of common stock (subject to adjustment in the event of any stock dividends and splits, reverse stock split, recapitalization, reorganization or similar transaction, as described in the Pre-Funded Warrants) with an exercise price of $0.001 per share. The Pre-Funded Warrants will expire upon the day they are exercised in full. The Pre-Funded Warrants are exercisable at any time prior to expiration except that the Pre-Funded Warrants cannot be exercised by the Investors if, after giving effect thereto, the Investors would beneficially own more than 9.99% of the Company’s common stock, subject to certain exceptions. The common stock and Pre-Funded Warrants were classified as equity in accordance with ASC 480 and the net proceeds from the transaction were recorded as a credit to additional paid-in capital. In accordance with Accounting Standards Codification Topic 260, Earnings Per Share

Net Loss per Share

Net Loss per Share	9 Months Ended
	Sep. 30, 2023
Net Loss per Share
Net Loss per Share	Note 8. Net Loss per Share As the Company had net losses for the three and nine months ended September 30, 2023 and 2022, all potential weighted average dilutive common shares were determined to be anti-dilutive. The following table sets forth the computation of basic and diluted net loss per share (in thousands, except share and per share data): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ September 30, ​ September 30, ​ 2023 2022 2023 2022 Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss ​ $ (34,105) ​ $ (31,232) ​ $ (106,290) ​ $ (93,199) Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average shares used to compute net loss per common share, basic and diluted ​ 59,182,899 ​ 49,107,639 ​ 55,542,543 48,971,329 Net loss per share, basic and diluted ​ $ (0.58) ​ $ (0.64) ​ $ (1.91) ​ $ (1.90) ​ The following outstanding shares of potentially dilutive securities have been excluded from diluted net loss per share computations for the periods presented because their inclusion would be anti-dilutive: ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ 2023 2022 Options to purchase common stock ​ 8,030,007 6,441,415 Common stock warrants ​ — ​ 2,750,000 Restricted stock units ​ 708,872 ​ 694,414 Performance stock units ​ 75,500 ​ 199,500 ESPP shares ​ 42,472 ​ 79,960 Total 8,856,851 10,165,289 ​

Subsequent Event

Subsequent Event	9 Months Ended
	Sep. 30, 2023
Subsequent Event
Subsequent Event	Note 9. Subsequent Event The Company announced the achievement of a $50.0 million milestone event under its license and collaboration agreement with Janssen on November 1, 2023. The milestone was earned when the third patient was dosed in the ICONIC-TOTAL Phase 3 clinical trial of JNJ-2113 in patients with moderate-to-severe psoriasis. ​

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2023
Summary of Significant Accounting Policies
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP have been condensed or omitted, and accordingly the condensed consolidated balance sheet as of September 30, 2023 has been derived from the Company’s unaudited consolidated financial statements at that date but does not include all of the information required by GAAP for complete consolidated financial statements. These unaudited interim condensed consolidated financial statements have been prepared on the same basis as the Company’s annual consolidated financial statements and, in the opinion of management, reflect all adjustments (consisting of normal recurring adjustments) that are necessary for a fair presentation of the Company’s condensed consolidated financial statements. The results of operations for the three and nine months ended September 30, 2023 are not necessarily indicative of the results to be expected for the year ending December 31, 2023 or for any future period. Effective January 1, 2023, the financial statements of Protagonist Australia use the U.S. dollar as the functional currency due to the expected nature of the ongoing operations of this subsidiary. The cumulative translation adjustment as of January 1, 2023 related to this subsidiary was not material. Prior to January 1, 2023, the financial statements of Protagonist Australia used the Australian dollar as the functional currency since the majority of expense transactions occurred in such currency. Foreign currency translation gains and losses are reported as a component of stockholders’ equity in accumulated other comprehensive loss on the condensed consolidated balance sheets. The accompanying unaudited condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto for the year ended December 31, 2022 included in the Company’s Annual Report on Form 10-K, filed with the SEC on March 15, 2023.
Principles of Consolidation	Principles of Consolidation The accompanying unaudited interim condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiary. All intercompany transactions and balances have been eliminated upon consolidation.
Use of Estimates	Use of Estimates The preparation of the condensed consolidated financial statements in conformity with GAAP requires management to make estimates, assumptions and judgments that affect the reported amounts of assets and liabilities and disclosure of contingent liabilities as of the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, accruals for research and development activities, stock-based compensation, income taxes, marketable securities and leases. Estimates related to revenue recognition include actual costs incurred versus total estimated costs of the Company’s deliverables to determine percentage of completion in addition to the application and estimates of potential revenue constraints in the determination of the transaction price under its license and collaboration agreements. Management bases these estimates on historical and anticipated results, trends, and various other assumptions that the Company believes are reasonable under the circumstances, including assumptions as to forecasted amounts and future events. Actual results could differ materially from these estimates. There has been uncertainty and disruption in the global economy and financial markets due to a number of factors, including the direct and indirect effects of COVID-19, geopolitical instability, inflationary pressures and domestic and global monetary and fiscal policy. The Company has taken into consideration any known impacts in its accounting estimates to date and is not aware of any additional specific events or circumstances that would require any additional updates to its estimates or judgments or a revision of the carrying value of its assets or liabilities as of the issuance of this report. These estimates may change as new events occur and additional information is obtained. Actual results could differ materially from these estimates under different assumptions or conditions.
Cash as Reported in Consolidated Statements of Cash Flows	Cash as Reported in Condensed Consolidated Statements of Cash Flows Cash as reported in the condensed consolidated statements of cash flows includes the aggregate amounts of cash and cash equivalents and the restricted cash as presented on the condensed consolidated balance sheets. Cash as reported in the condensed consolidated statements of cash flows consists of (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ 2023 2022 Cash and cash equivalents ​ $ 230,527 ​ $ 152,816 Restricted cash – noncurrent ​ 225 ​ 225 Total cash reported on condensed consolidated statements of cash flows ​ $ 230,752 ​ $ 153,041
Investment Impairment	Investment Impairment ​ As of each reporting date, the Company assesses each of its investments in available-for-sale debt securities whose fair value is below its cost basis to determine if the investment’s impairment is due to credit-related factors or noncredit-related factors. Factors considered in determining whether an impairment is credit-related include the extent to which the investment’s fair value is less than its cost basis, declines in published credit ratings, issuer default on interest or principal payments, and declines in the financial condition and near-term prospects of the issuer. Credit-related impairments on available-for-sale debt securities are recognized as an allowance for credit losses with a corresponding adjustment to other income (expense), net. The portion of the impairment that is not credit-related is recorded as a reduction of other comprehensive income (loss), net of applicable taxes. ​ Pursuant to Accounting Standard Update (“ASU”) 2016-13, Financial Instruments - Credit Losses (Topic 326) ​
Stock-based Compensation	Stock-Based Compensation Expense ​ The Company measures its stock-based awards made to its equity plan participants based on the estimated fair values of the awards as of the grant date. For stock option awards, the Company uses the Black-Scholes option-pricing model to estimate fair values. For restricted stock unit awards, the estimated fair value is generally the fair market value of the underlying stock on the grant date. Stock-based compensation expense is recognized over the requisite service period and is based on the value of the portion of stock-based payment awards that is ultimately expected to vest. The Company recognizes forfeitures of stock-based awards as they occur. ​ The Company has granted performance share units (“PSUs”) to certain executives of the Company. Stock-based compensation expense associated with PSUs is based on the fair value of the Company’s common stock on the grant date, which equals the closing price of the Company’s common stock on the grant date. The Company recognizes compensation expense over the vesting periods of the awards that are ultimately expected to vest when the achievement of the related performance obligation becomes probable. ​ Total stock-based compensation expense was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ September 30, ​ September 30, ​ 2023 2022 2023 2022 Research and development ​ $ 3,780 ​ $ 3,858 ​ $ 13,171 ​ $ 11,290 General and administrative ​ 2,985 ​ 2,092 ​ 9,521 ​ 7,400 Total stock-based compensation expense ​ $ 6,765 ​ $ 5,950 ​ $ 22,692 ​ $ 18,690
Recently Adopted Accounting Pronouncement	Recently Adopted Accounting Pronouncements In June 2016, the Financial Accounting Standard Board (“FASB”) issued ASU 2016-13. The guidance requires measurement and recognition of expected credit losses for financial assets at the time financial assets are initially recognized in the financial statements. The measurement of expected credit losses is based on historical credit loss information as well as current and future economic factors. ASU 2016-13 also eliminates the concept of “other-than-temporary” impairment when evaluating available-for-sale debt securities and instead focuses on determining whether any impairment is a result of credit loss or other factors. In November 2019, the FASB issued ASU 2019-10, Financial Instruments – Credit Losses (Topic 326): Effective Dates

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2023
Summary of Significant Accounting Policies
Schedule of cash as reported in the consolidated statements of cash flows	Cash as reported in the condensed consolidated statements of cash flows consists of (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ 2023 2022 Cash and cash equivalents ​ $ 230,527 ​ $ 152,816 Restricted cash – noncurrent ​ 225 ​ 225 Total cash reported on condensed consolidated statements of cash flows ​ $ 230,752 ​ $ 153,041
Schedule of stock-based compensation expense	Total stock-based compensation expense was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ September 30, ​ September 30, ​ 2023 2022 2023 2022 Research and development ​ $ 3,780 ​ $ 3,858 ​ $ 13,171 ​ $ 11,290 General and administrative ​ 2,985 ​ 2,092 ​ 9,521 ​ 7,400 Total stock-based compensation expense ​ $ 6,765 ​ $ 5,950 ​ $ 22,692 ​ $ 18,690

License and Collaboration Agr_2

License and Collaboration Agreement (Tables)	9 Months Ended
	Sep. 30, 2023
License and Collaboration Agreement.
Schedule of changes in contract assets and liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ ​ ​ ​ ​ Balance at ​ ​ Beginning of ​ ​ ​ ​ ​ End of Nine Months Ended September 30, 2023 Period ​ Additions Deductions Period Contract assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Receivable from collaboration partner ​ $ 10 ​ $ 41 ​ ​ (51) ​ $ — Contract liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Payable to collaboration partner ​ $ 69 ​ $ 11 ​ ​ (77) ​ $ 3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ ​ ​ ​ ​ ​ ​ Balance at ​ ​ Beginning of ​ ​ ​ ​ ​ End of Nine Months Ended September 30, 2022 Period ​ Additions Deductions Period Contract assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Receivable from collaboration partner ​ $ 1,566 ​ $ 25,165 ​ $ (26,606) ​ $ 125 Contract liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred revenue ​ $ 1,601 ​ $ 25,757 ​ $ (27,358) ​ $ — Payable to collaboration partner ​ $ 899 ​ $ 52 ​ $ (919) ​ $ 32

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2023
Fair Value Measurements
Schedule of fair value of financial assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 ​ Level 1 Level 2 Level 3 Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 70,470 ​ $ — ​ $ — $ 70,470 Certificates of deposit ​ — ​ ​ 4,799 ​ — 4,799 Commercial paper ​ — ​ ​ 132,226 ​ — 132,226 Corporate debt securities ​ ​ — ​ ​ 1,980 ​ ​ — ​ ​ 1,980 U.S. Treasury and agency securities ​ ​ — ​ ​ 108,786 ​ ​ — ​ ​ 108,786 Total financial assets ​ $ 70,470 ​ $ 247,791 $ — $ 318,261 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ Level 1 Level 2 Level 3 Total Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 54,292 ​ $ — ​ $ — $ 54,292 Commercial paper ​ — ​ 110,227 ​ — 110,227 Corporate debt securities ​ — ​ 10,741 — 10,741 U.S. Treasury and agency securities ​ ​ ​ ​ ​ 57,242 ​ ​ — 57,242 Total financial assets ​ $ 54,292 ​ $ 178,210 $ — $ 232,502

Cash Equivalents and Marketab_2

Cash Equivalents and Marketable Securities (Tables)	9 Months Ended
	Sep. 30, 2023
Cash Equivalents and Marketable Securities
Schedule of cash equivalents and marketable securities	Cash equivalents and marketable securities consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 ​ ​ Amortized ​ Gross Unrealized ​ ​ Cost Gains Losses Fair Value Money market funds ​ $ 70,470 ​ $ — ​ $ — ​ $ 70,470 Certificates of deposit ​ ​ 4,798 ​ ​ 1 ​ ​ — ​ 4,799 Commercial paper ​ 132,275 ​ ​ — ​ ​ (49) ​ 132,226 Corporate debt securities ​ ​ 1,982 ​ ​ — ​ ​ (2) ​ ​ 1,980 U.S. Treasury and agency securities ​ ​ 108,794 ​ ​ 9 ​ ​ (17) ​ ​ 108,786 Total cash equivalents and marketable securities ​ $ 318,319 ​ $ 10 $ (68) ​ $ 318,261 Classified as: ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ ​ ​ ​ ​ ​ ​ $ 226,052 Marketable securities ​ ​ ​ ​ ​ ​ ​ 90,224 Marketable securities - noncurrent ​ ​ ​ ​ ​ ​ ​ 1,985 Total cash equivalents and marketable securities ​ ​ ​ ​ ​ ​ ​ $ 318,261 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ Amortized ​ Gross Unrealized ​ ​ Cost Gains Losses Fair Value Money market funds ​ $ 54,292 ​ $ — $ — ​ $ 54,292 Commercial paper ​ 110,257 ​ — (30) ​ 110,227 Corporate debt securities ​ 10,756 ​ — (15) ​ 10,741 U.S. Treasury and agency securities ​ ​ 57,251 ​ ​ 27 ​ ​ (36) ​ ​ 57,242 Total cash equivalents and marketable securities ​ $ 232,556 ​ $ 27 $ (81) ​ $ 232,502 Classified as: ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ ​ ​ ​ ​ ​ ​ $ 120,891 Marketable securities ​ ​ ​ ​ ​ ​ ​ 111,611 Total cash equivalents and marketable securities ​ ​ ​ ​ ​ ​ ​ $ 232,502

Balance Sheet Components (Table

Balance Sheet Components (Tables)	9 Months Ended
	Sep. 30, 2023
Balance Sheet Components
Summary of prepaid expenses and other current assets	Prepaid expenses and other current assets consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2023 ​ 2022 Prepaid insurance ​ $ 1,871 ​ $ 1,417 Prepaid clinical and research related expenses ​ ​ 578 ​ ​ 2,746 Prepaid licenses ​ ​ 410 ​ ​ 489 Other prepaid expenses ​ 1,206 ​ 1,018 Other receivable ​ ​ 65 ​ ​ 42 Prepaid expenses and other current assets ​ $ 4,130 ​ $ 5,712
Summary of property and equipment net	Property and equipment, net consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2023 ​ 2022 Laboratory equipment ​ $ 5,281 ​ $ 4,817 Furniture and computer equipment ​ 1,123 ​ 1,089 Leasehold improvements ​ 963 ​ 913 Total property and equipment ​ 7,367 ​ 6,819 Accumulated depreciation ​ (5,946) ​ (5,254) Property and equipment, net ​ $ 1,421 ​ $ 1,565
Schedule of accrued expenses and other payables	Accrued expenses and other payables consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2023 ​ 2022 Accrued clinical and research related expenses ​ $ 19,666 ​ $ 19,109 Accrued employee related expenses ​ 4,528 ​ 4,967 Accrued professional service fees ​ ​ 471 ​ ​ 464 Other ​ 144 ​ 415 Total accrued expenses and other payables ​ $ 24,809 ​ $ 24,955 ​

Net Loss per Share (Tables)

Net Loss per Share (Tables)	9 Months Ended
	Sep. 30, 2023
Net Loss per Share
Schedule of computation of the basic and diluted net loss per share attributable to common stockholders	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ September 30, ​ September 30, ​ 2023 2022 2023 2022 Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss ​ $ (34,105) ​ $ (31,232) ​ $ (106,290) ​ $ (93,199) Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted-average shares used to compute net loss per common share, basic and diluted ​ 59,182,899 ​ 49,107,639 ​ 55,542,543 48,971,329 Net loss per share, basic and diluted ​ $ (0.58) ​ $ (0.64) ​ $ (1.91) ​ $ (1.90)
Schedule of potentially dilutive securities excluded from diluted net loss per share calculations	​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ 2023 2022 Options to purchase common stock ​ 8,030,007 6,441,415 Common stock warrants ​ — ​ 2,750,000 Restricted stock units ​ 708,872 ​ 694,414 Performance stock units ​ 75,500 ​ 199,500 ESPP shares ​ 42,472 ​ 79,960 Total 8,856,851 10,165,289 ​

Organization and Description _2

Organization and Description of Business - Liquidity (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($) segment	Dec. 31, 2022 USD ($)
Organization and Description of Business
Number of operating segments | segment	1
Net losses from operations since inception
Cash, cash equivalents and marketable securities	$ 322,700
Accumulated deficit	$ (643,045)	$ (536,755)

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Aggregate amounts of cash and cash equivalents and the restricted cash
Cash and cash equivalents	$ 230,527	$ 125,744	$ 152,816
Restricted cash - noncurrent	225	225	225
Total cash reported on condensed consolidated statements of cash flows	$ 230,752	$ 125,969	$ 153,041	$ 123,890

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 6,765	$ 5,950	$ 22,692	$ 18,690
Research and Development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	3,780	3,858	13,171	11,290
General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 2,985	$ 2,092	$ 9,521	$ 7,400

License and Collaboration Agr_3

License and Collaboration Agreement - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Jul. 27, 2021	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021	Mar. 31, 2020	May 07, 2019	Jul. 13, 2017
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
License and collaboration revenue		$ 0	$ 0	$ 0	$ 26,581
Revenue from Contract with Customer, Product and Service [Extensible List]		License and Collaboration Agreement	License and Collaboration Agreement	License and Collaboration Agreement	License and Collaboration Agreement
Revenue recognized			$ 0		$ 900
Janssen | License and Collaboration Agreement | Three phase 1 studies of second-generation compounds
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Eligible amount received							$ 7,500
Janssen | License and Collaboration Agreement | 3rd patient in the first Phase 2 clinical trial for any second-generation compound for a second indication
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Eligible amount received						$ 25,000
Janssen | Original Agreement | Upfront cash payment
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment										$ 50,000
Janssen | Restated Agreement | Second-generation Oral Interleukin ("IL")-23 Receptor Antagonist Development Compound
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Eligible amount received								$ 5,000
Janssen | Restated Agreement | Minimum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of royalties on net product sales	6%
Janssen | Restated Agreement | Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of royalties on net product sales	10%
Janssen | Restated Agreement | License and Collaboration Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Eligible amount received									$ 25,000
Janssen | Restated Agreement | License and Collaboration Agreement | Dosing of the 3rd patient in a Phase 3 clinical trial for a second-generation compound for any indication
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upcoming potential development milestones		$ 50,000		$ 50,000
Janssen | Restated Agreement | License and Collaboration Agreement | Phase 3 clinical trial for a second-generation compound for any indication
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upcoming potential development milestones		115,000		115,000
Janssen | Restated Agreement | License and Collaboration Agreement | Filing of New Drug Application ("NDA") for second-generation compound with the U.S. Food and Drug Administration
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upcoming potential development milestones		35,000		35,000
Janssen | Restated Agreement | License and Collaboration Agreement | FDA approval of NDA for second-generation compound
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upcoming potential development milestones		50,000		50,000
Janssen | Restated Agreement | License and Collaboration Agreement | Phase 2 studies for second-generation products
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upcoming potential development milestones						$ 25,000
Janssen | Restated Agreement | License and Collaboration Agreement | 3rd patient in the first Phase 2 clinical trial for any second-generation compound for a second indication
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upcoming potential development milestones		10,000		10,000
Janssen | Restated Agreement | License and Collaboration Agreement | Dosing Of Third Patient In Phase 3 Clinical Trial For Second Generation Compound For A Second Indication [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upcoming potential development milestones		$ 15,000		$ 15,000

License and Collaboration Agr_4

License and Collaboration Agreement - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Contract assets:
Receivable from collaboration partner, Balance at Beginning of Period	$ 10	$ 1,566
Receivable from collaboration partner, Additions	41	25,165
Receivable from collaboration partner, Deductions	51	26,606
Receivable from collaboration partner, Balance at End of Period		125
Contract liabilities:
Payable to collaboration partner, Balance at Beginning of Period	69	899
Payable to collaboration partner, Additions	11	52
Payable to collaboration partner, Deductions	(77)	(919)
Payable to collaboration partner, Balance at End of Period	$ 3	32
Deferred revenue, Balance at Beginning of Period		1,601
Deferred revenue, Additions		25,757
Deferred revenue, Deductions		$ (27,358)

Fair Value Measurements (Detail

Fair Value Measurements (Details) - Recurring - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	$ 318,261	$ 232,502
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	70,470	54,292
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	4,799
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	132,226	110,227
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	1,980	10,741
U.S. Treasury and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	108,786	57,242
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	70,470	54,292
Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	70,470	54,292
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	247,791	178,210
Level 2 | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	4,799
Level 2 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	132,226	110,227
Level 2 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	1,980	10,741
Level 2 | U.S. Treasury and agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	$ 108,786	$ 57,242

Cash Equivalents and Marketab_3

Cash Equivalents and Marketable Securities - Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Cash Equivalents and Marketable Securities
Total cash equivalents and marketable securities, Amortized Cost	$ 318,319	$ 232,556
Total cash equivalents and marketable securities, Gross Unrealized Gains	10	27
Total cash equivalents and marketable securities, Gross Unrealized Losses	(68)	(81)
Total cash equivalents and marketable securities, Fair Value	318,261	232,502
Corporate debt securities
Cash Equivalents and Marketable Securities
Total cash equivalents and marketable securities, Amortized Cost	1,982	10,756
Total cash equivalents and marketable securities, Gross Unrealized Losses	(2)	(15)
Total cash equivalents and marketable securities, Fair Value	1,980	10,741
U.S. Treasury and agency securities
Cash Equivalents and Marketable Securities
Total cash equivalents and marketable securities, Amortized Cost	108,794	57,251
Total cash equivalents and marketable securities, Gross Unrealized Gains	9	27
Total cash equivalents and marketable securities, Gross Unrealized Losses	(17)	(36)
Total cash equivalents and marketable securities, Fair Value	108,786	57,242
Money market funds
Cash Equivalents and Marketable Securities
Total cash equivalents and marketable securities, Amortized Cost	70,470	54,292
Total cash equivalents and marketable securities, Fair Value	70,470	54,292
Commercial paper
Cash Equivalents and Marketable Securities
Total cash equivalents and marketable securities, Amortized Cost	132,275	110,257
Total cash equivalents and marketable securities, Gross Unrealized Losses	(49)	(30)
Total cash equivalents and marketable securities, Fair Value	132,226	$ 110,227
Certificates of deposit
Cash Equivalents and Marketable Securities
Total cash equivalents and marketable securities, Amortized Cost	4,798
Total cash equivalents and marketable securities, Gross Unrealized Gains	1
Total cash equivalents and marketable securities, Fair Value	$ 4,799

Cash Equivalents and Marketab_4

Cash Equivalents and Marketable Securities - Classification of Cash Equivalents and Marketable Securities (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Classified as:
Cash equivalents	$ 226,052,000	$ 120,891,000
Marketable securities - current	90,224,000	111,611,000
Marketable securities - noncurrent	1,985,000	0
Total cash equivalents and marketable securities	$ 318,261,000	$ 232,502,000
Contractual maturities
Maximum period of current contractual maturities	1 year	1 year
Minimum period of noncurrent contractual maturities	1 year	1 year
Maximum period of Noncurrent contractual maturities	2 years	2 years
Realized Gain (loss)	$ 0	$ 0
Credit-related losses to be recognized	$ 0

Balance Sheet Components - Prep

Balance Sheet Components - Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Prepaid expenses and other current assets
Prepaid insurance	$ 1,871	$ 1,417
Prepaid clinical and research related expenses	578	2,746
Prepaid licenses	410	489
Other prepaid expenses	1,206	1,018
Other receivable	65	42
Prepaid expenses and other current assets	$ 4,130	$ 5,712

Balance Sheet Components - Prop

Balance Sheet Components - Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Property and Equipment
Total property and equipment	$ 7,367	$ 6,819
Accumulated depreciation	(5,946)	(5,254)
Property and equipment, net	1,421	1,565
Laboratory equipment
Property and Equipment
Total property and equipment	5,281	4,817
Furniture and computer equipment
Property and Equipment
Total property and equipment	1,123	1,089
Leasehold improvements
Property and Equipment
Total property and equipment	$ 963	$ 913

Balance Sheet Components - Accr

Balance Sheet Components - Accrued Expenses and Other Payables (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Accrued Expenses and Other Payables
Accrued clinical and research related expenses	$ 19,666	$ 19,109
Accrued employee related expenses	4,528	4,967
Accrued professional service fees	471	464
Other	144	415
Total accrued expenses and other payables	$ 24,809	$ 24,955

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands

1 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

Aug. 08, 2018

Aug. 31, 2023

Apr. 30, 2023

Aug. 31, 2022

Jan. 31, 2022

Nov. 30, 2019

Aug. 31, 2018

Sep. 30, 2023

Jun. 30, 2023

Mar. 31, 2023

Sep. 30, 2022

Sep. 30, 2023

Sep. 30, 2022

Dec. 31, 2022

Stock transactions

Common stock sold, price per share

$ 20

Warrants issued to purchase common stock, number of shares

2,705,252

Exercise Price (per share)

$ 0.001

$ 0

$ 0

Common stock issued (in shares)

5,000,000

Gross proceeds form exercise of warrants

$ 33,813

$ 33,813

Proceeds from exercise of Warrants in exchange for issuance of Pre-funded Warrants

$ 34,400

33,813

Minimum percentage of common stock held by investors for not exercise of warrants

9.99%

Number of shares issued upon exercise of warrants

44,748

Proceeds from public offering of common stock, net of issuance costs

$ 107,800

$ 107,790

2019 Sales Agreement

Stock transactions

Common stock issued (in shares)

422,367

Maximum aggregate offering price

$ 75,000

Proceeds from public offering of common stock, net of issuance costs

$ 14,600

2022 Sales Agreement

Stock transactions

Common stock issued (in shares)

0

0

1,749,199

0

Maximum aggregate offering price

$ 100,000

Aggregate net proceeds

$ 24,300

Over-Allotment Option

Stock transactions

Common stock sold, price per share

$ 20

Common stock issued (in shares)

750,000

Common Stock

Stock transactions

Number of shares issued upon exercise of warrants

44,748

399,997

44,748

399,997

Investors | Private Placement

Stock transactions

Aggregate shares of common stock sold

2,750,000

Common stock sold, price per share

$ 8

Net proceeds from sale of common stock

$ 21,700

Warrants issued to purchase common stock, number of shares

2,750,000

Warrants exercisable date

Aug. 08, 2023

$10.00 per share | Investors | Private Placement

Stock transactions

Warrants to purchase common stock (in shares)

1,375,000

Exercise Price (per share)

$ 10

$15.00 per share | Investors | Private Placement

Stock transactions

Warrants to purchase common stock (in shares)

1,375,000

Exercise Price (per share)

$ 15

Net Loss per Share - Computatio

Net Loss per Share - Computation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Numerator:
Net loss	$ (34,105)	$ (31,232)	$ (106,290)	$ (93,199)
Denominator:
Weighted-average shares used to compute net loss per common share, Basic	59,182,899	49,107,639	55,542,543	48,971,329
Weighted-average shares used to compute net loss per common share, Diluted	59,182,899	49,107,639	55,542,543	48,971,329
Net loss per share, basic	$ (0.58)	$ (0.64)	$ (1.91)	$ (1.90)
Net loss per share, diluted	$ (0.58)	$ (0.64)	$ (1.91)	$ (1.90)

Net Loss per Share - Antidiluti

Net Loss per Share - Antidilutive Securities (Details) - shares	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Potentially dilutive securities have been excluded from diluted net loss per share calculations
Anti-dilutive securities (in shares)	8,856,851	10,165,289
Options to purchase common stock
Potentially dilutive securities have been excluded from diluted net loss per share calculations
Anti-dilutive securities (in shares)	8,030,007	6,441,415
Common stock warrants
Potentially dilutive securities have been excluded from diluted net loss per share calculations
Anti-dilutive securities (in shares)		2,750,000
Restricted stock units
Potentially dilutive securities have been excluded from diluted net loss per share calculations
Anti-dilutive securities (in shares)	708,872	694,414
Performance stock units
Potentially dilutive securities have been excluded from diluted net loss per share calculations
Anti-dilutive securities (in shares)	75,500	199,500
ESPP shares
Potentially dilutive securities have been excluded from diluted net loss per share calculations
Anti-dilutive securities (in shares)	42,472	79,960

Subsequent Event (Details)

Subsequent Event (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
	Nov. 01, 2023	Sep. 30, 2022	Sep. 30, 2022
Subsequent Event [Line Items]
Revenue recognized		$ 0	$ 0.9
License and Collaboration Agreement | Subsequent Event [Member]
Subsequent Event [Line Items]
Revenue recognized	$ 50