Enanta Pharmaceuticals (ENTA) 10-Q 8 Aug 23 2023 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Jun. 30, 2023	Aug. 01, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Trading Symbol	ENTA
Entity Registrant Name	ENANTA PHARMACEUTICALS, INC
Entity Central Index Key	0001177648
Current Fiscal Year End Date	--09-30
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity File Number	001-35839
Security Exchange Name	NASDAQ
Entity Tax Identification Number	04-3205099
Entity Address, Address Line One	500 Arsenal Street
Entity Address, City or Town	Watertown
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02472
City Area Code	617
Title of 12(b) Security	Common Stock, par value $0.01 per share
Local Phone Number	607-0800
Entity Incorporation, State or Country Code	DE
Document Transition Report	false
Document Quarterly Report	true
Entity Interactive Data Current	Yes
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		21,055,392

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2023	Sep. 30, 2022
Current assets:
Cash and cash equivalents	$ 95,177	$ 43,994
Short-term marketable securities	291,408	205,238
Accounts receivable	18,892	20,318
Prepaid expenses and other current assets	17,071	13,445
Income tax receivable	25,917	28,718
Total current assets	448,465	311,713
Long-term marketable securities	5,924	29,285
Property and equipment, net	12,014	6,173
Operating lease, right-of-use assets	23,968	23,575
Restricted cash	3,968	3,968
Other long-term assets	830	696
Total assets	495,169	375,410
Current liabilities:
Accounts payable	7,932	6,000
Accrued expenses and other current liabilities	18,196	20,936
Liability related to the sale of future royalties	36,693	0
Operating lease liabilities	5,368	2,891
Total current liabilities	68,189	29,827
Liability related to the sale of future royalties, net of current portion	164,979	0
Operating lease liabilities, net of current portion	22,333	22,372
Series 1 nonconvertible preferred stock	1,423	1,423
Other long-term liabilities	426	454
Total liabilities	257,350	54,076
Commitments and contingencies (Note 11)
Stockholders' equity:
Common stock; $0.01 par value per share, 100,000 shares authorized; 21,056 and 20,791 shares issued and outstanding at June 30, 2023 and September 30, 2022, respectively	210	208
Additional paid-in capital	418,001	398,029
Accumulated other comprehensive loss	(1,504)	(3,724)
Accumulated deficit	(178,888)	(73,179)
Total stockholders' equity	237,819	321,334
Total liabilities and stockholders' equity	$ 495,169	$ 375,410

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares shares in Thousands	Jun. 30, 2023	Sep. 30, 2022
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000	100,000
Common stock, shares issued	21,056	20,791
Common stock, shares outstanding	21,056	20,791

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Total revenue	$ 18,892	$ 19,479	$ 60,272	$ 65,843
Operating expenses:
Research and development	42,987	39,090	127,357	129,726
General and administrative	12,618	12,929	39,092	32,913
Total operating expenses	55,605	52,019	166,449	162,639
Loss from operations	(36,713)	(32,540)	(106,177)	(96,796)
Other income (expense):
Interest expense	(1,997)	0	(1,997)	0
Interest and investment income, net	3,866	393	6,696	942
Total other income, net	1,869	393	4,699	942
Loss before income taxes	(34,844)	(32,147)	(101,478)	(95,854)
Income tax (expense) benefit	(4,221)	447	(4,231)	447
Net loss	$ (39,065)	$ (31,700)	$ (105,709)	$ (95,407)
Net loss per share:
Basic	$ (1.86)	$ (1.53)	$ (5.05)	$ (4.64)
Diluted	$ (1.86)	$ (1.53)	$ (5.05)	$ (4.64)
Weighted average shares outstanding:
Basic	21,054	20,710	20,939	20,552
Diluted	21,054	20,710	20,939	20,552
Royalty [Member]
Total revenue	$ 18,892	$ 19,479	$ 59,272	$ 65,843
License [Member]
Total revenue	$ 0	$ 0	$ 1,000	$ 0

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Net loss	$ (39,065)	$ (31,700)	$ (105,709)	$ (95,407)
Other comprehensive income (loss):
Net unrealized gains (losses) on marketable securities	311	(583)	2,220	(3,238)
Total other comprehensive income (loss)	311	(583)	2,220	(3,238)
Comprehensive loss	$ (38,754)	$ (32,283)	$ (103,489)	$ (98,645)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	(Accumulated Deficit) Retained Earnings [Member]
Beginning Balance at Sep. 30, 2021	$ 399,429	$ 202	$ 351,033	$ (382)	$ 48,576
Beginning Balance, Shares at Sep. 30, 2021		20,238,000
Exercise of stock options	10,409	$ 2	10,407
Exercise of stock options, Shares		248,000
Vesting of restricted stock units, net of withholding	(777)	$ 1	(778)
Vesting of restricted stock units, net of withholding, Shares		20,000
Stock-based compensation expense	6,062		6,062
Other comprehensive (loss) income	(624)			(624)
Net loss	(30,115)				(30,115)
Ending Balance at Dec. 31, 2021	384,384	$ 205	366,724	(1,006)	18,461
Ending Balance, Shares at Dec. 31, 2021		20,506,000
Beginning Balance at Sep. 30, 2021	399,429	$ 202	351,033	(382)	48,576
Beginning Balance, Shares at Sep. 30, 2021		20,238,000
Other comprehensive (loss) income	(3,238)
Net loss	(95,407)
Ending Balance at Jun. 30, 2022	$ 338,023	$ 207	388,267	(3,620)	(46,831)
Ending Balance, Shares at Jun. 30, 2022	20,720,000
Beginning Balance at Sep. 30, 2021	$ 399,429	$ 202	351,033	(382)	48,576
Beginning Balance, Shares at Sep. 30, 2021		20,238,000
Net loss	(121,755)
Ending Balance at Sep. 30, 2022	321,334	$ 208	398,029	(3,724)	(73,179)
Ending Balance, Shares at Sep. 30, 2022		20,791,000
Beginning Balance at Dec. 31, 2021	384,384	$ 205	366,724	(1,006)	18,461
Beginning Balance, Shares at Dec. 31, 2021		20,506,000
Exercise of stock options	3,802	$ 1	3,801
Exercise of stock options, Shares		97,000
Vesting of restricted stock units, net of withholding	(451)		(451)
Vesting of restricted stock units, net of withholding, Shares		15,000
Stock-based compensation expense	6,471		6,471
Other comprehensive (loss) income	(2,031)			(2,031)
Net loss	(33,592)				(33,592)
Ending Balance at Mar. 31, 2022	358,583	$ 206	376,545	(3,037)	(15,131)
Ending Balance, Shares at Mar. 31, 2022		20,618,000
Exercise of stock options	4,120	$ 1	4,119
Exercise of stock options, Shares		102,000
Stock-based compensation expense	7,603		7,603
Other comprehensive (loss) income	(583)			(583)
Net loss	(31,700)				(31,700)
Ending Balance at Jun. 30, 2022	$ 338,023	$ 207	388,267	(3,620)	(46,831)
Ending Balance, Shares at Jun. 30, 2022	20,720,000
Beginning Balance at Sep. 30, 2022	$ 321,334	$ 208	398,029	(3,724)	(73,179)
Beginning Balance, Shares at Sep. 30, 2022		20,791,000
Exercise of stock options	1,126	$ 1	1,125
Exercise of stock options, Shares		56,000
Vesting of restricted stock units, net of withholding	(825)		(825)
Vesting of restricted stock units, net of withholding, Shares		37,000
Stock-based compensation expense	7,139		7,139
Other comprehensive (loss) income	1,049			1,049
Net loss	(28,986)				(28,986)
Ending Balance at Dec. 31, 2022	300,837	$ 209	405,468	(2,675)	(102,165)
Ending Balance, Shares at Dec. 31, 2022		20,884,000
Beginning Balance at Sep. 30, 2022	$ 321,334	$ 208	398,029	(3,724)	(73,179)
Beginning Balance, Shares at Sep. 30, 2022		20,791,000
Exercise of stock options, Shares	124,000
Ending Balance at Mar. 31, 2023	$ 269,375	$ 210	410,803	(1,815)	(139,823)
Ending Balance, Shares at Mar. 31, 2023		21,049,000
Beginning Balance at Sep. 30, 2022	321,334	$ 208	398,029	(3,724)	(73,179)
Beginning Balance, Shares at Sep. 30, 2022		20,791,000
Other comprehensive (loss) income	2,220
Net loss	(105,709)
Ending Balance at Jun. 30, 2023	237,819	$ 210	418,001	(1,504)	(178,888)
Ending Balance, Shares at Jun. 30, 2023		21,056,000
Beginning Balance at Dec. 31, 2022	300,837	$ 209	405,468	(2,675)	(102,165)
Beginning Balance, Shares at Dec. 31, 2022		20,884,000
Exercise of stock options	882	$ 1	881
Exercise of stock options, Shares		61,000
Vesting of restricted stock units, net of withholding	(2,909)		(2,909)
Vesting of restricted stock units, net of withholding, Shares		104,000
Stock-based compensation expense	7,363		7,363
Other comprehensive (loss) income	860			860
Net loss	(37,658)				(37,658)
Ending Balance at Mar. 31, 2023	269,375	$ 210	410,803	(1,815)	(139,823)
Ending Balance, Shares at Mar. 31, 2023		21,049,000
Exercise of stock options	200		200
Exercise of stock options, Shares		7,000
Stock-based compensation expense	6,998		6,998
Other comprehensive (loss) income	311			311
Net loss	(39,065)				(39,065)
Ending Balance at Jun. 30, 2023	$ 237,819	$ 210	$ 418,001	$ (1,504)	$ (178,888)
Ending Balance, Shares at Jun. 30, 2023		21,056,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Cash flows from operating activities
Net loss	$ (105,709)	$ (95,407)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	21,500	20,136
Depreciation and amortization expense	1,702	2,318
Non cash interest expense associated with the sale of future royalties	1,997	0
Premium paid on marketable securities	(73)	(846)
Amortization (accretion) of premiums (discounts) on marketable securities	(2,792)	1,118
Loss on disposal of property and equipment	7	0
Change in operating assets and liabilities:
Accounts receivable	1,426	4,097
Prepaid expenses and other current assets	(3,626)	2,648
Income tax receivable	2,801	8,527
Operating lease, right-of-use assets	3,187	3,932
Other long-term assets	(134)	(611)
Accounts payable	2,682	(8,555)
Accrued expenses	(3,350)	(3,253)
Operating lease liabilities	(1,142)	(3,235)
Other long-term liabilities	(28)	(117)
Net cash used in operating activities	(81,552)	(69,248)
Cash flows from investing activities
Purchase of marketable securities	(267,274)	(162,714)
Proceeds from maturities and sales of marketable securities	209,550	190,068
Purchase of property and equipment	(7,690)	(688)
Net cash provided by (used in) investing activities	(65,414)	26,666
Cash flows from financing activities
Proceeds from exercise of stock options	2,208	18,331
Proceeds from the sale of future royalties	200,000	0
Debt issuance cost	(325)	0
Payments for settlement of share-based awards	(3,734)	(1,228)
Net cash provided by financing activities	198,149	17,103
Net increase (decrease) in cash, cash equivalents and restricted cash	51,183	(25,479)
Cash, cash equivalents and restricted cash as of the beginning of period	47,962	57,814
Cash, cash equivalents and restricted cash as of the end of period	99,145	32,335
Supplemental disclosure of non-cash information:
Purchases of fixed assets included in accounts payable and accrued expenses	1,075	412
Operating lease liabilities arising from obtaining right-of-use assets	$ 3,580	$ 22,984

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended		12 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ (39,065)	$ (37,658)	$ (28,986)	$ (31,700)	$ (33,592)	$ (30,115)	$ (105,709)	$ (95,407)	$ (121,755)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Jun. 30, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Nature of the Business and Basi

Nature of the Business and Basis of Presentation	9 Months Ended
	Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business and Basis of Presentation	1. Nature of the Business and Basis of Presentation Enanta Pharmaceuticals, Inc. (collectively with its subsidiary, the “Company”), incorporated in Delaware in 1995 , is a biotechnology company that uses its robust, chemistry-driven approach and drug discovery capabilities to become a leader in the discovery and development of small molecule drugs, with an emphasis on treatments for viral infections. The Company discovered glecaprevir, the second of two protease inhibitors discovered and developed through its collaboration with AbbVie for the treatment of chronic infection with hepatitis C virus (“HCV”). Glecaprevir is co-formulated as part of AbbVie’s leading direct-acting antiviral (“DAA”) combination treatment for HCV, which is marketed under the tradenames MAVYRET® (U.S.) and MAVIRET®(ex-U.S.) (glecaprevir/pibrentasvir). Royalties from the Company’s AbbVie collaboration and its existing financial resources provide funding to support the Company’s wholly-owned research and development programs, which are primarily focused on the following disease targets: respiratory syncytial virus (“RSV”), SARS-CoV-2, human metapneumovirus (“hMPV”) and hepatitis B virus (“HBV”). The Company is subject to many of the risks common to companies in the biotechnology industry, including but not limited to, the uncertainties of research and development, competition from technological innovations of others, dependence on collaborative arrangements, protection of proprietary technology, dependence on key personnel and compliance with government regulation. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approvals, prior to commercialization. These efforts require significant amounts of capital, adequate personnel and infrastructure, and extensive compliance reporting capabilities. COVID-19 In March 2020, the World Health Organization declared COVID-19 a global pandemic and countries worldwide implemented various measures to contain the spread of the SARS-CoV-2 virus. National, state and local governments in affected regions implemented varying safety precautions, including quarantines, border closures, increased border controls, travel restrictions, shelter-in-place orders and shutdowns, business closures, cancellations of public gatherings and other measures. The pandemic caused minor disruptions in the supply chains for the Company’s research and product candidates, significant delays in the conduct of ongoing clinical trials and reductions in the number of patients accessing AbbVie’s HCV regimens which impacted royalties earned. The extent to which COVID-19 will have further impact on the Company’s business, results of operations and financial condition will depend on future developments that are highly uncertain and cannot be accurately predicted, including new variants and public health actions taken to contain their impact, as well as the cumulative economic impact of both of those factors and the public health impact of the ending of emergency public health measures. Unaudited Interim Financial Information The consolidated balance sheet as of September 30, 2022 was derived from audited financial statements but does not include all disclosures required by accounting principles generally accepted in the United States of America (“GAAP”). The accompanying unaudited consolidated financial statements as of June 30, 2023 and for the three and nine months ended June 30, 2023 and 2022 have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. These consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended September 30, 2022. In the opinion of management, all adjustments, consisting of normal recurring adjustments necessary for a fair statement of the Company’s financial position as of June 30, 2023 and results of operations for the three and nine months ended June 30, 2023 and 2022 and cash flows for the nine months ended June 30, 2023 and 2022 have been made. The results of operations for the three and nine months ended June 30, 2023 are not necessarily indicative of the results of operations that may be expected for subsequent quarters or the year ending September 30, 2023. The accompanying consolidated financial statements have been prepared in conformity with GAAP. All amounts in the consolidated financial statements and in the notes to the consolidated financial statements, except per share amounts, are in thousands unless otherwise indicated. The accompanying consolidated financial statements have been prepared based on continuity of operations, realization of assets and the satisfaction of liabilities and commitments in the ordinary course of business. The Company began reporting a net loss in fiscal 2020 and reported a net loss of $ 105,709 for the nine months ended June 30, 2023 and $ 121,755 for the year ended September 30, 2022. As of June 30, 2023, the Company had an accumulated deficit of $ 178,888 . The Company expects to continue to generate operating losses for the foreseeable future as the Company continues to advance its wholly-owned programs. As of June 30, 2023, the Company had $ 392,509 in cash, cash equivalents and short-term and long-term marketable securities. The Company expects that its cash, cash equivalents, short-term and long-term marketable securities will be sufficient to fund its operating expenses and capital expenditure requirements for at least 12 months from the issuance date of the interim consolidated financial statements. The Company may seek additional funding through equity offerings, non-dilutive financings, collaborations, strategic alliances or licensing agreements. The Company may not be able to obtain sufficient financing on acceptable terms, or at all, and the Company may not be able to enter into collaborations or other arrangements. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. If the Company is unable to obtain funding, the Company could be forced to delay, reduce or eliminate some or all of its research and development programs, product expansion or commercialization efforts, or the Company may be unable to continue operations.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies For the Company’s Significant Accounting Policies, please refer to its Annual Report on Form 10-K for the fiscal year ended September 30, 2022 and the liability related to the sale of future royalties below. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, management’s judgments with respect to its revenue arrangements; liability related to the sale of future royalties; valuation of stock-based awards and the accrual of research and development expenses. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Liability Related to the Sale of Future Royalties In April 2023, the Company entered into a royalty sale agreement with an affiliate of OMERS, pursuant to which the Company was paid a $ 200,000 cash purchase price in exchange for 54.5 % of the Company’s future quarterly royalty payments on net sales of MAVYRET/MAVIRET. The Company recognized the $ 200,000 received from OMERS as a liability on its consolidated balance sheets because the $200,000 will be paid back to OMERS up to a 1.42 capped amount and the Company has significant continuing involvement under the AbbVie Agreement. Interest expense for the liability related to the sale of future royalties is recognized using the effective interest rate method over the term of the royalty sale agreement. The liability related to the sale of future royalties and related interest expense are based on current estimates of future royalties, which the Company determines by using third-party forecasts of MAVYRET/MAVIRET sales. The Company periodically assesses the forecasted sales and to the extent the amount or timing of future estimated royalty payments is materially different than previous estimates, the Company will account for any such change by adjusting the liability related to the sale of future royalties and prospectively recognizing the related non-cash interest expense. Net Income (Loss) per Share Basic net income (loss) per common share is computed by dividing the net income (loss) by the weighted average number of shares of common stock outstanding for the period. Diluted net income (loss) per common share is computed by dividing net income (loss) by the weighted average number of common shares outstanding for the period, including potential dilutive common shares assuming the dilutive effect of outstanding stock options and unvested restricted stock units. For periods presented, diluted net loss per common share is the same as basic net loss per common share, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. The Company reported net losses for each of the three and nine months ended June 30, 2023 and 2022 . The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: As of June 30, 2023 2022 (in thousands) Options to purchase common stock 4,455 4,020 Unvested rTSRUs 81 98 Unvested PSUs 81 98 Unvested restricted stock units 423 201 Recently Issued Accounting Pronouncements Other accounting standards that have been issued or proposed by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s consolidated financial statements upon adoption.

Fair Value of Financial Assets

Fair Value of Financial Assets and Liabilities	9 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets and Liabilities	3. Fair Value of Financial Assets and Liabilities The following tables present information about the Company’s financial assets and liabilities that were subject to fair value measurement on a recurring basis as of June 30, 2023 and September 30, 2022, and indicate the fair value hierarchy of the valuation inputs utilized to determine such fair value: Fair Value Measurements as of June 30, 2023 Using: Level 1 Level 2 Level 3 Total (in thousands) Assets: Cash equivalents: Money market funds $ 30,373 $ — $ — $ 30,373 U.S. Treasury notes 59,591 — — 59,591 Marketable securities: U.S. Treasury notes 194,261 — — 194,261 Corporate bonds — 36,256 — 36,256 Commercial paper — 66,815 — 66,815 $ 284,225 $ 103,071 $ — $ 387,296 Liabilities: Series 1 nonconvertible preferred stock $ — $ — $ 1,423 $ 1,423 $ — $ — $ 1,423 $ 1,423 Fair Value Measurements as of September 30, 2022 Using: Level 1 Level 2 Level 3 Total (in thousands) Assets: Cash equivalents: Money market funds $ 13,905 $ — $ — $ 13,905 Marketable securities: U.S. Treasury notes 91,328 — — 91,328 Corporate bonds — 76,411 — 76,411 Commercial paper — 66,784 — 66,784 $ 105,233 $ 143,195 $ — $ 248,428 Liabilities: Series 1 nonconvertible preferred stock $ — $ — $ 1,423 $ 1,423 $ — $ — $ 1,423 $ 1,423 During the three and nine months ended June 30, 2023 and 2022 , there were no transfers between Level 1, Level 2 and Level 3. The outstanding shares of Series 1 nonconvertible preferred stock as of June 30, 2023 and September 30, 2022 are measured at fair value. These outstanding shares are financial instruments that might require a transfer of assets because of the liquidation features in the contract and are therefore recorded as liabilities and measured at fair value. The fair value of the outstanding shares is based on significant inputs not observable in the market, which represent a Level 3 measurement within the fair value hierarchy. The Company utilizes a probability-weighted valuation model which takes into consideration various outcomes that may require the Company to transfer assets upon liquidation. Changes in the fair values of the Series 1 nonconvertible preferred stock are recognized in other income (expense) in the consolidated statements of operations. The recurring Level 3 fair value measurements of the Company’s outstanding Series 1 nonconvertible preferred stock using probability-weighted discounted cash flow include the following significant unobservable inputs: Range June 30, September 30, Unobservable Input 2023 2022 Probabilities of payout 0 %- 65 % 0 %- 65 % Discount rate 7.25 % 7.25 % There were no changes in the fair value of nonconvertible preferred stock during the three and nine months ended June 30, 2023 or 2022. In April 2023, the Company entered into a royalty sale agreement with an affiliate of OMERS, pursuant to which the Company was paid a $ 200,000 cash purchase price in exchange for 54.5 % of future quarterly royalty payments on net sales of MAVYRET/MAVIRET, after June 30, 2023, through June 30, 2032, subject to a cap on aggregate payments equal to 1.42 times the purchase price. The Company accounted for the upfront payment as a liability related to the sale of future royalties which is recorded at fair value. The fair value of the liability is based on significant inputs not observable in the market, which represent a Level 3 measurement within the fair value hierarchy. The Company estimates the liability based on current estimates of future royalties expected to be paid to OMERS over the next 10 years. Changes in the fair value of the liability are recognized as interest expense in the consolidated statements of operations. The recurring Level 3 fair value measurement includes a weighted average interest rate of approximately 5.5 % as of June 30, 2023. See Note 7 for a rollforward of the liability.

Marketable Securities

Marketable Securities	9 Months Ended
	Jun. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	4. Marketable Securities As of June 30, 2023 and September 30, 2022, the fair value of available-for-sale marketable securities, by type of security, was as follows: June 30, 2023 Amortized Gross Gross Credit Losses Fair Value (in thousands) Corporate bonds $ 37,210 $ — $ ( 954 ) $ — $ 36,256 Commercial paper 66,815 — — — 66,815 U.S. Treasury notes 194,427 22 ( 188 ) — 194,261 $ 298,452 $ 22 $ ( 1,142 ) $ — $ 297,332 September 30, 2022 Amortized Gross Gross Credit Losses Fair Value (in thousands) Corporate bonds $ 78,663 $ — $ ( 2,252 ) $ — $ 76,411 Commercial paper 66,784 — — — 66,784 U.S. Treasury notes 92,416 — ( 1,088 ) — 91,328 $ 237,863 $ — $ ( 3,340 ) $ — $ 234,523 As of June 30, 2023 and September 30, 2022 , marketable securities consisted of investments that mature within one year , with the exception of certain corporate bonds and U.S. Treasury notes, which have maturities between one and two years and an aggregate fair value of $ 5,924 and $ 29,285 , respectively.

Accrued Expenses

Accrued Expenses	9 Months Ended
	Jun. 30, 2023
Payables and Accruals [Abstract]
Accrued Expenses	5. Accrued Expenses Accrued expenses and other current liabilities consisted of the following as of June 30, 2023 and September 30, 2022: June 30, September 30, 2023 2022 (in thousands) Accrued pharmaceutical drug manufacturing $ 5,508 $ 6,932 Accrued research and development expenses 5,702 5,532 Accrued payroll and related expenses 5,031 6,439 Accrued other 1,955 2,033 $ 18,196 $ 20,936

AbbVie Collaboration

AbbVie Collaboration	9 Months Ended
	Jun. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
AbbVie Collaboration	6. AbbVie Collaboration The Company has a Collaborative Development and License Agreement (as amended, the “AbbVie Agreement”), with AbbVie to identify, develop and commercialize HCV NS3 and NS3/4A protease inhibitor compounds, including paritaprevir and glecaprevir, under which the Company has received license payments, proceeds from a sale of preferred stock, research funding payments, milestone payments and royalties totaling approximately $ 1,268,000 through June 30, 2023. The Company is receiving annually tiered royalties per Company protease product ranging from ten percent up to twenty percent, or on a blended basis from ten percent up to the high teens, on the portion of AbbVie’s calendar year net sales of each HCV regimen that is allocated to the protease inhibitor in the regimen. Beginning with each January 1, the cumulative net sales of a given royalty-bearing protease inhibitor product start at zero for purposes of calculating the tiered royalties on a product-by-product basis.

Series 1 Nonconvertible Preferr

Series 1 Nonconvertible Preferred Stock	9 Months Ended
	Jun. 30, 2023
Debt Disclosure [Abstract]
Series 1 Nonconvertible Preferred Stock	. Series 1 Nonconvertible Preferred Stock As of June 30, 2023 , 1,930 shares of Series 1 nonconvertible preferred stock were issued and outstanding. Since these shares qualify as a derivative, the outstanding shares are carried at fair value as a liability on the Company’s consolidated balance sheets.

Liability Related to the Sale o

Liability Related to the Sale of Future Royalties	9 Months Ended
	Jun. 30, 2023
Nonmonetary Transactions [Abstract]
Liability Related to the Sale of Future Royalties	7. Liability Related to the Sale of Future Royalties In April 2023, the Company entered into a royalty sale agreement with an affiliate of OMERS, pursuant to which the Company was paid a $ 200,000 cash purchase price in exchange for 54.5 % of future quarterly royalty payments on net sales of MAVYRET/MAVIRET, after June 30, 2023, through June 30, 2032, subject to a cap on aggregate payments equal to 1.42 times the purchase price. Because the royalty sale agreement will be paid back to OMERS up to a capped amount as well as the Company’s significant continuing involvement in the generation of future cash flows under its AbbVie Agreement, the Company recorded the proceeds from the transaction as a liability on its consolidated balance sheets which will be amortized as interest expense in the consolidated statements of operations under the effective interest rate method over the life of the royalty sale agreement. The Company will continue to record the full amount of royalties earned on MAVYRET/MAVIRET sales as royalty revenue in the consolidated statements of operations. The Company’s liability related to the sale of future royalties is estimated based on forecasted worldwide MAVYRET/MAVYRET royalties to be paid to OMERS over the course of the royalty sale agreement. This estimate requires significant judgment, including the amount and timing of royalty payments up until the end of the royalty sale agreement, which is estimated to be the stated term of June 30, 2032. As royalties are earned by OMERS, the liability is reduced on the Company’s consolidated balance sheets. At June 30, 2023, the estimated future cash flows resulted in an effective annual imputed interest rate of approximately 5.5 %. The following table summarizes the activity of the liability related to the sale of future royalties: Liability related to the sale of future royalties (in thousands) Balance - September 30, 2022 $ — Proceeds from sale of future royalties 200,000 Debt issuance cost ( 325 ) Royalty payments — Non-cash interest expense 1,997 Balance - June 30, 2023 $ 201,672

Stock-Based Awards

Stock-Based Awards	9 Months Ended
	Jun. 30, 2023
Share-Based Payment Arrangement [Abstract]
Stock-Based Awards	9. Stock-Based Awards The Company grants stock-based awards, including stock options, restricted stock units and other unit awards under its 2019 Equity Incentive Plan (the “2019 Plan”), which was approved by its stockholders on February 28, 2019 and amended in March 2021, March 2022 and March 2023. The Company also has outstanding stock option awards under its 2012 Equity Incentive Plan (the “2012 Plan”) but is no longer granting awards under this plan. The following table summarizes stock option activity, including performance-based options, for the year-to-date period ending June 30, 2023: Shares Weighted Weighted Aggregate (in thousands) (in years) (in thousands) Outstanding as of September 30, 2022 3,993 $ 53.57 6.2 $ 28,778 Granted 755 44.87 Exercised ( 124 ) 17.83 Forfeited ( 169 ) 62.89 Outstanding as of June 30, 2023 4,455 $ 52.74 6.3 $ 2 Options vested and expected to vest as of 4,455 $ 52.74 6.3 $ 2 Options exercisable as of June 30, 2023 2,922 $ 51.92 5.0 $ 2 Market and Performance-Based Stock Unit Awards The Company awards both performance share units, or PSUs, and relative total stockholder return units, or rTSRUs, to its executive officers. The number of units granted represents the target number of shares of common stock that may be earned; however, the actual number of shares that may be earned ranges from 0 % to 150 % of the target number. The number of shares cancelled represents the target number of shares, less any shares that vested. The following table summarizes PSU and rTSRU activity for the year-to-date period ending June 30, 2023: PSUs rTSRUs Shares Weighted Shares Weighted (in thousands) (in thousands) Unvested as of September 30, 2022 101 $ 54.50 101 $ 36.14 Granted 50 47.24 50 36.91 Vested ( 70 ) 44.58 ( 70 ) 23.89 Unvested as of June 30, 2023 81 $ 58.58 81 $ 45.82 During the nine months ended June 30, 2023, a total of 100 % of the target PSUs and 127 % of the target rTSRUs granted in December 2020 vested, resulting in the issuance of an aggregate of 104 common shares, net of share withholding. Restricted Stock Units The following table summarizes the restricted stock unit activity for the year-to-date period ending June 30, 2023: Restricted Stock Weighted (in thousands) Unvested as of September 30, 2022 219 $ 64.03 Granted 277 45.00 Vested ( 56 ) 61.10 Cancelled ( 17 ) 54.92 Unvested as of June 30, 2023 423 $ 52.32 Stock-Based Compensation Expense During the three and nine months ended June 30, 2023 and 2022 the Company recognized the following stock-based compensation expense: Three Months Ended June 30, Nine Months Ended June 30, 2023 2022 2023 2022 (in thousands) Research and development $ 2,385 $ 2,202 $ 7,437 $ 7,496 General and administrative 4,613 5,401 14,063 12,640 $ 6,998 $ 7,603 $ 21,500 $ 20,136 Three Months Ended June 30, Nine Months Ended June 30, 2023 2022 2023 2022 (in thousands) Stock options $ 4,963 $ 5,079 $ 15,020 $ 14,790 rTSRUs 440 207 1,447 1,171 Performance stock units — 1,559 542 1,930 Restricted stock units 1,595 758 4,491 2,245 $ 6,998 $ 7,603 $ 21,500 $ 20,136 During the three and nine months ended June 30, 2023 and 2022, the Company recognized stock-based compensation expense for performance-based stock units for which vesting became probable upon achievement of performance-based targets that occurred during the performance period. As of June 30, 2023, the Company had an aggregate of $ 69,426 of unrecognized stock-based compensation cost, which is expected to be recognized over a weighted average period of 2.4 years.

Income Taxes

Income Taxes	9 Months Ended
	Jun. 30, 2023
Income Tax Disclosure [Abstract]
Income Taxes	10. Income Taxes For the three and nine months ended June 30, 2023 , the Company recorded income tax expense of $ 4,221 and $ 4,231 , respectively, due to $ 200,000 received from the royalty sale agreement with OMERS in April 2023 which is taxable for federal and state purposes. This was partially offset by utilization of federal net operating losses and research and development tax credit carryforwards as well as a deduction for foreign derived intangible income. For the three and nine months ended June 30, 2022 , the Company recorded an income tax benefit of $ 447 due to the release of a state tax reserve during the period.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Jun. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	11. Commitments and Contingencies Litigation and Contingencies Related to Use of Intellectual Property From time to time, the Company may become subject to legal proceedings, claims and litigation arising in the ordinary course of business. For example, third parties might allege that the Company or its collaborators are infringing their patent rights or that the Company is otherwise violating their intellectual property rights. Such third parties may resort to litigation against the Company or its collaborators, which the Company has agreed to indemnify. With respect to some of these patents, the Company expects that it will be required to obtain licenses and could be required to pay license fees or royalties, or both. These licenses may not be available on acceptable terms, or at all. A costly license, or inability to obtain a necessary license, would have a material adverse effect on the Company’s financial condition, results of operations or cash flows. The Company accrues contingent liabilities when it is probable that future expenditures will be made and such expenditures can be reasonably estimated. On June 21, 2022, the Company filed suit in the United States District Court for the District of Massachusetts, against Pfizer, Inc. seeking damages for infringement of U.S. Patent No. 11,358,953 (the ’953 Patent) in the manufacture, use and sale of Pfizer’s COVID-19 antiviral, Paxlovid ™ (nirmatrelvir tablets; ritonavir tablets). The United States Patent and Trademark Office awarded the '953 Patent to the Company in June 2022 based on the Company's July 2020 patent application describing coronavirus protease inhibitors invented by the Company. The Company is seeking fair compensation for Pfizer’s use of a coronavirus protease inhibitor claimed in the ‘953 patent. The Company records all legal expenses associated with the patent infringement suit as incurred in the consolidated statements of operations. The Company currently is not a party to any other litigation. Indemnification Agreements In the ordinary course of business, the Company may provide indemnifications of varying scope and terms to customers, vendors, lessors, business partners, and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from services to be provided to the Company, or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and its executive officers that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. In addition, the Company maintains directors’ and officers’ insurance coverage. The Company does not believe that the outcome of any claims under indemnification arrangements will have a material effect on its financial position, results of operations or cash flows, and has not accrued any liabilities related to such obligations in its consolidated financial statements as of June 30, 2023. Leases The Company leases laboratory and office space under various non-cancelable operating leases. There have been no material changes to the Company’s leases during the three and nine months ended June 30, 2023. For additional information, please read Note 11, Leases, to the consolidated financial statements in the Company's Annual Report on Form 10-K for the fiscal year ended September 30, 2022 .

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements, and the reported amounts of revenues and expenses during the reporting period. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, management’s judgments with respect to its revenue arrangements; liability related to the sale of future royalties; valuation of stock-based awards and the accrual of research and development expenses. Estimates are periodically reviewed in light of changes in circumstances, facts and experience.
Liability Related to the Sale of Future Royalties	Liability Related to the Sale of Future Royalties In April 2023, the Company entered into a royalty sale agreement with an affiliate of OMERS, pursuant to which the Company was paid a $ 200,000 cash purchase price in exchange for 54.5 % of the Company’s future quarterly royalty payments on net sales of MAVYRET/MAVIRET. The Company recognized the $ 200,000 received from OMERS as a liability on its consolidated balance sheets because the $200,000 will be paid back to OMERS up to a 1.42 capped amount and the Company has significant continuing involvement under the AbbVie Agreement. Interest expense for the liability related to the sale of future royalties is recognized using the effective interest rate method over the term of the royalty sale agreement. The liability related to the sale of future royalties and related interest expense are based on current estimates of future royalties, which the Company determines by using third-party forecasts of MAVYRET/MAVIRET sales. The Company periodically assesses the forecasted sales and to the extent the amount or timing of future estimated royalty payments is materially different than previous estimates, the Company will account for any such change by adjusting the liability related to the sale of future royalties and prospectively recognizing the related non-cash interest expense.
Net Income (Loss) per Share	Net Income (Loss) per Share Basic net income (loss) per common share is computed by dividing the net income (loss) by the weighted average number of shares of common stock outstanding for the period. Diluted net income (loss) per common share is computed by dividing net income (loss) by the weighted average number of common shares outstanding for the period, including potential dilutive common shares assuming the dilutive effect of outstanding stock options and unvested restricted stock units. For periods presented, diluted net loss per common share is the same as basic net loss per common share, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. The Company reported net losses for each of the three and nine months ended June 30, 2023 and 2022 . The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: As of June 30, 2023 2022 (in thousands) Options to purchase common stock 4,455 4,020 Unvested rTSRUs 81 98 Unvested PSUs 81 98 Unvested restricted stock units 423 201
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements Other accounting standards that have been issued or proposed by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s consolidated financial statements upon adoption.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Diluted Net Loss Per Share With Anti-dilutive effect	The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: As of June 30, 2023 2022 (in thousands) Options to purchase common stock 4,455 4,020 Unvested rTSRUs 81 98 Unvested PSUs 81 98 Unvested restricted stock units 423 201

Fair Value of Financial Asset_2

Fair Value of Financial Assets and Liabilities (Tables)	9 Months Ended
	Jun. 30, 2023
Fair Value Disclosures [Abstract]
Financial Assets and Liabilities that were Subject to Fair Value Measurement on Recurring Basis	The following tables present information about the Company’s financial assets and liabilities that were subject to fair value measurement on a recurring basis as of June 30, 2023 and September 30, 2022, and indicate the fair value hierarchy of the valuation inputs utilized to determine such fair value: Fair Value Measurements as of June 30, 2023 Using: Level 1 Level 2 Level 3 Total (in thousands) Assets: Cash equivalents: Money market funds $ 30,373 $ — $ — $ 30,373 U.S. Treasury notes 59,591 — — 59,591 Marketable securities: U.S. Treasury notes 194,261 — — 194,261 Corporate bonds — 36,256 — 36,256 Commercial paper — 66,815 — 66,815 $ 284,225 $ 103,071 $ — $ 387,296 Liabilities: Series 1 nonconvertible preferred stock $ — $ — $ 1,423 $ 1,423 $ — $ — $ 1,423 $ 1,423 Fair Value Measurements as of September 30, 2022 Using: Level 1 Level 2 Level 3 Total (in thousands) Assets: Cash equivalents: Money market funds $ 13,905 $ — $ — $ 13,905 Marketable securities: U.S. Treasury notes 91,328 — — 91,328 Corporate bonds — 76,411 — 76,411 Commercial paper — 66,784 — 66,784 $ 105,233 $ 143,195 $ — $ 248,428 Liabilities: Series 1 nonconvertible preferred stock $ — $ — $ 1,423 $ 1,423 $ — $ — $ 1,423 $ 1,423
Fair Value Measurements of the Company's Outstanding Series 1 Nonconvertible Preferred Stock	The recurring Level 3 fair value measurements of the Company’s outstanding Series 1 nonconvertible preferred stock using probability-weighted discounted cash flow include the following significant unobservable inputs: Range June 30, September 30, Unobservable Input 2023 2022 Probabilities of payout 0 %- 65 % 0 %- 65 % Discount rate 7.25 % 7.25 %

Marketable Securities (Tables)

Marketable Securities (Tables)	9 Months Ended
	Jun. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Fair Value of Available-for-Sale Marketable Securities by Type of Security	As of June 30, 2023 and September 30, 2022, the fair value of available-for-sale marketable securities, by type of security, was as follows: June 30, 2023 Amortized Gross Gross Credit Losses Fair Value (in thousands) Corporate bonds $ 37,210 $ — $ ( 954 ) $ — $ 36,256 Commercial paper 66,815 — — — 66,815 U.S. Treasury notes 194,427 22 ( 188 ) — 194,261 $ 298,452 $ 22 $ ( 1,142 ) $ — $ 297,332 September 30, 2022 Amortized Gross Gross Credit Losses Fair Value (in thousands) Corporate bonds $ 78,663 $ — $ ( 2,252 ) $ — $ 76,411 Commercial paper 66,784 — — — 66,784 U.S. Treasury notes 92,416 — ( 1,088 ) — 91,328 $ 237,863 $ — $ ( 3,340 ) $ — $ 234,523

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
	Jun. 30, 2023
Payables and Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following as of June 30, 2023 and September 30, 2022: June 30, September 30, 2023 2022 (in thousands) Accrued pharmaceutical drug manufacturing $ 5,508 $ 6,932 Accrued research and development expenses 5,702 5,532 Accrued payroll and related expenses 5,031 6,439 Accrued other 1,955 2,033 $ 18,196 $ 20,936

Liability Related to the Sale_2

Liability Related to the Sale of Future Royalties (Tables)	9 Months Ended
	Jun. 30, 2023
Nonmonetary Transactions [Abstract]
Summary of the Liability Related to the Sale of Future Royalties	The following table summarizes the activity of the liability related to the sale of future royalties: Liability related to the sale of future royalties (in thousands) Balance - September 30, 2022 $ — Proceeds from sale of future royalties 200,000 Debt issuance cost ( 325 ) Royalty payments — Non-cash interest expense 1,997 Balance - June 30, 2023 $ 201,672

Stock-Based Awards (Tables)

Stock-Based Awards (Tables)	9 Months Ended
	Jun. 30, 2023
Summary of Stock Option Activity Including Performance Based Options	The following table summarizes stock option activity, including performance-based options, for the year-to-date period ending June 30, 2023: Shares Weighted Weighted Aggregate (in thousands) (in years) (in thousands) Outstanding as of September 30, 2022 3,993 $ 53.57 6.2 $ 28,778 Granted 755 44.87 Exercised ( 124 ) 17.83 Forfeited ( 169 ) 62.89 Outstanding as of June 30, 2023 4,455 $ 52.74 6.3 $ 2 Options vested and expected to vest as of 4,455 $ 52.74 6.3 $ 2 Options exercisable as of June 30, 2023 2,922 $ 51.92 5.0 $ 2
Summary of Restricted Stock Unit Activity	The following table summarizes the restricted stock unit activity for the year-to-date period ending June 30, 2023: Restricted Stock Weighted (in thousands) Unvested as of September 30, 2022 219 $ 64.03 Granted 277 45.00 Vested ( 56 ) 61.10 Cancelled ( 17 ) 54.92 Unvested as of June 30, 2023 423 $ 52.32
Stock-Based Compensation Expense	During the three and nine months ended June 30, 2023 and 2022 the Company recognized the following stock-based compensation expense: Three Months Ended June 30, Nine Months Ended June 30, 2023 2022 2023 2022 (in thousands) Research and development $ 2,385 $ 2,202 $ 7,437 $ 7,496 General and administrative 4,613 5,401 14,063 12,640 $ 6,998 $ 7,603 $ 21,500 $ 20,136 Three Months Ended June 30, Nine Months Ended June 30, 2023 2022 2023 2022 (in thousands) Stock options $ 4,963 $ 5,079 $ 15,020 $ 14,790 rTSRUs 440 207 1,447 1,171 Performance stock units — 1,559 542 1,930 Restricted stock units 1,595 758 4,491 2,245 $ 6,998 $ 7,603 $ 21,500 $ 20,136
Performance Share Units and Relative Total Stockholder Return Units [Member]
Summary of PSUs and rTSRUs Activity	The following table summarizes PSU and rTSRU activity for the year-to-date period ending June 30, 2023: PSUs rTSRUs Shares Weighted Shares Weighted (in thousands) (in thousands) Unvested as of September 30, 2022 101 $ 54.50 101 $ 36.14 Granted 50 47.24 50 36.91 Vested ( 70 ) 44.58 ( 70 ) 23.89 Unvested as of June 30, 2023 81 $ 58.58 81 $ 45.82 During the nine months ended June 30, 2023, a total of 100 % of the target PSUs and 127 % of the target rTSRUs granted in December 2020 vested, resulting in the issuance of an aggregate of 104 common shares, net of share withholding.

Nature of the Business and Ba_2

Nature of the Business and Basis of Presentation - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended		12 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2023	Jun. 30, 2022	Sep. 30, 2022
Entity incorporated, in year							1995
Net loss	$ 39,065	$ 37,658	$ 28,986	$ 31,700	$ 33,592	$ 30,115	$ 105,709	$ 95,407	$ 121,755
Accumulated deficit	178,888						178,888		$ 73,179
Cash, cash equivalents and short-term and long-term marketable securities	$ 392,509						$ 392,509

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Liability Related to the Sale of Future Royalties (Detail) $ in Thousands	1 Months Ended
	Apr. 30, 2023 USD ($)
OCM Life Sciences Portfolio LP [Member]
Nonmonetary Transaction [Line Items]
Payment received royalty purchase agreement	$ 200,000
Percentage of future quarterly royalty payments on net sales received in cash	54.50%
Omers Royalty Sale Agreement [Member ]
Nonmonetary Transaction [Line Items]
Payment received royalty purchase agreement	$ 200,000
Percentage of future quarterly royalty payments on net sales received in cash	54.50%

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Diluted Net Loss Per Share Attributable to Common Stockholders With Anti-dilutive effect (Detail) - shares shares in Thousands	9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	4,455	4,020
Unvested rTSRUs [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	81	98
Unvested PSUs [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	81	98
Unvested Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	423	201

Fair Value of Financial Asset_3

Fair Value of Financial Assets and Liabilities - Financial Assets and Liabilities that were Subject to Fair Value Measurement on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Sep. 30, 2022
Assets:
Marketable securities	$ 297,332	$ 234,523
Assets, Fair Value Disclosure, Total	387,296	248,428
Liabilities:
Liabilities, Fair Value Disclosure, Total	1,423	1,423
Series 1 Nonconvertible Preferred Stock [Member]
Liabilities:
Liabilities	1,423	1,423
Level 1 [Member]
Assets:
Assets, Fair Value Disclosure, Total	284,225	105,233
Liabilities:
Liabilities, Fair Value Disclosure, Total	0	0
Level 1 [Member] | Series 1 Nonconvertible Preferred Stock [Member]
Liabilities:
Liabilities	0	0
Level 2 [Member]
Assets:
Assets, Fair Value Disclosure, Total	103,071	143,195
Liabilities:
Liabilities, Fair Value Disclosure, Total	0	0
Level 2 [Member] | Series 1 Nonconvertible Preferred Stock [Member]
Liabilities:
Liabilities	0	0
Level 3 [Member]
Assets:
Assets, Fair Value Disclosure, Total	0	0
Liabilities:
Liabilities, Fair Value Disclosure, Total	1,423	1,423
Level 3 [Member] | Series 1 Nonconvertible Preferred Stock [Member]
Liabilities:
Liabilities	1,423	1,423
U.S. Treasury Notes [Member]
Assets:
Cash equivalents	59,591
Marketable securities	194,261	91,328
U.S. Treasury Notes [Member] | Level 1 [Member]
Assets:
Cash equivalents	59,591
Marketable securities	194,261	91,328
U.S. Treasury Notes [Member] | Level 2 [Member]
Assets:
Cash equivalents	0
Marketable securities	0	0
U.S. Treasury Notes [Member] | Level 3 [Member]
Assets:
Cash equivalents	0
Marketable securities	0	0
Corporate Bonds [Member]
Assets:
Marketable securities	36,256	76,411
Corporate Bonds [Member] | Level 1 [Member]
Assets:
Marketable securities	0	0
Corporate Bonds [Member] | Level 2 [Member]
Assets:
Marketable securities	36,256	76,411
Corporate Bonds [Member] | Level 3 [Member]
Assets:
Marketable securities	0	0
Commercial Paper [Member]
Assets:
Marketable securities	66,815	66,784
Commercial Paper [Member] | Level 1 [Member]
Assets:
Marketable securities	0	0
Commercial Paper [Member] | Level 2 [Member]
Assets:
Marketable securities	66,815	66,784
Commercial Paper [Member] | Level 3 [Member]
Assets:
Marketable securities	0	0
Money Market Funds [Member]
Assets:
Cash equivalents	30,373	13,905
Money Market Funds [Member] | Level 1 [Member]
Assets:
Cash equivalents	30,373	13,905
Money Market Funds [Member] | Level 2 [Member]
Assets:
Cash equivalents	0	0
Money Market Funds [Member] | Level 3 [Member]
Assets:
Cash equivalents	$ 0	$ 0

Fair Value of Financial Asset_4

Fair Value of Financial Assets and Liabilities - Additional Information (Detail)	1 Months Ended	3 Months Ended		9 Months Ended
	Apr. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers between Level 1, Level 2 and Level 3		$ 0	$ 0	$ 0	$ 0
Omers Royalty Sale Agreement [Member ]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Proceeds from sale of future royalties	$ 200,000,000
Percentage of future quarterly royalty payments on net sales received in cash	54.50%
Future quarterly royalty payments, description	after June 30, 2023, through June 30, 2032, subject to a cap on aggregate payments equal to 1.42 times the purchase price.
Omers Royalty Sale Agreement [Member ] | Fair Value Measurements Recurring [Member] | Level 3 [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Royalty purchase agreement interest rate		5.5		5.5
Series 1 Nonconvertible Preferred Stock [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in fair value of nonconvertible preferred stock		$ 0	$ 0	$ 0	$ 0

Fair Value of Financial Asset_5

Fair Value of Financial Assets and Liabilities - Fair Value Measurements of the Company's Outstanding Series 1 Nonconvertible Preferred Stock (Detail) - Level 3 [Member] - Series 1 Nonconvertible Preferred Stock [Member]	Jun. 30, 2023	Sep. 30, 2022
Probabilities of Payout [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	0	0
Probabilities of Payout [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	65	65
Discount Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Range	7.25	7.25

Marketable Securities - Fair Va

Marketable Securities - Fair Value of Available-for-Sale Marketable Securities by Type of Security (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Sep. 30, 2022
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 298,452	$ 237,863
Gross Unrealized Gains	22	0
Gross Unrealized Losses	(1,142)	(3,340)
Fair Value	297,332	234,523
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	37,210	78,663
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(954)	(2,252)
Fair Value	36,256	76,411
U.S. Treasury Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	194,427	92,416
Gross Unrealized Gains	22	0
Gross Unrealized Losses	(188)	(1,088)
Fair Value	194,261	91,328
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	66,815	66,784
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	$ 66,815	$ 66,784

Marketable Securities - Additio

Marketable Securities - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2023	Sep. 30, 2022
Schedule of Available-for-sale Securities [Line Items]
Long-term marketable securities	$ 5,924	$ 29,285
Maximum [Member] | Short Term Marketable Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Maturity period of the marketable securities	1 year
Long Term Marketable Securities [Member] | Maximum [Member] | Corporate Bonds and U.S. Treasury Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Maturity period of the marketable securities	2 years
Long Term Marketable Securities [Member] | Minimum [Member] | Corporate Bonds and U.S. Treasury Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Maturity period of the marketable securities	1 year

Accrued Expenses - Accrued Expe

Accrued Expenses - Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Sep. 30, 2022
Accrued expenses:
Accrued pharmaceutical drug manufacturing	$ 5,508	$ 6,932
Accrued research and development expenses	5,702	5,532
Accrued payroll and related expenses	5,031	6,439
Accrued other	1,955	2,033
Accrued expenses	$ 18,196	$ 20,936

AbbVie Collaboration - Addition

AbbVie Collaboration - Additional Information (Detail) - AbbVie [Member]	9 Months Ended
	Jun. 30, 2023 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Cash consideration received under collaboration from milestone payments and royalties	$ 1,268,000
Collaboration agreement tiered royalty description	from ten percent up to twenty percent, or on a blended basis from ten percent up to the high teens, on the portion of AbbVie’s calendar year net sales

Liability Related to the Sale_3

Liability Related to the Sale of Future Royalties - Additional Information (Detail) - OCM Life Sciences Portfolio LP [Member] $ in Thousands	1 Months Ended	9 Months Ended
	Apr. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)
Nonmonetary Transaction [Line Items]
Payment received royalty purchase agreement	$ 200,000
Percentage of future quarterly royalty payments on net sales received in cash	54.50%
Future royalty payment description	after June 30, 2023, through June 30, 2032, subject to a cap on aggregate payments equal to 1.42 times the purchase price.
Royalty purchase agreement annual imputed interest rate		5.5
Sale Of Future Royalties [Member]
Nonmonetary Transaction [Line Items]
Payment received royalty purchase agreement		$ 200,000

Liability Related to the Sale_4

Liability Related to the Sale of Future Royalties - Summary Of The Liability Related To The Sale Of Future Royalties (Details) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended
	Apr. 30, 2023	Jun. 30, 2023	Jun. 30, 2022
Nonmonetary Transaction [Line Items]
Debt issuance cost		$ (325)	$ 0
Royalty payments		0
OCM Life Sciences Portfolio LP [Member]
Nonmonetary Transaction [Line Items]
Proceeds from sale of future royalties	$ 200,000
Sale Of Future Royalties [Member] | OCM Life Sciences Portfolio LP [Member]
Nonmonetary Transaction [Line Items]
Royalty liability - beginning balance		0
Proceeds from sale of future royalties		200,000
Debt issuance cost		(325)
Non-cash interest expense		1,997
Royalty liability - ending balance		$ 201,672

Series 1 Nonconvertible Prefe_2

Series 1 Nonconvertible Preferred Stock - Additional Information (Detail) - Series 1 Nonconvertible Preferred Stock [Member]	Jun. 30, 2023 shares
Class Of Stock [Line Items]
Preferred stock, shares issued	1,930,000
Preferred stock, shares outstanding	1,930,000

Stock-Based Awards - Summary of

Stock-Based Awards - Summary of Stock Option Activity Including Performance Based Options (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2023	Jun. 30, 2023	Sep. 30, 2022
Options
Outstanding as of beginning of period	3,993	3,993
Granted	755
Exercised	(124)
Forfeited	(169)
Outstanding as of end of period		4,455	3,993
Options vested and expected to vest as of end of period		4,455
Options exercisable as of end of period		2,922
Weighted Average Exercise Price
Outstanding	$ 53.57	$ 53.57
Granted	44.87
Exercised	17.83
Forfeited	$ 62.89
Outstanding		52.74	$ 53.57
Options vested and expected to vest as of end of period		52.74
Options exercisable as of end of period		$ 51.92
Weighted Average Remaining Contractual Term
Outstanding as of end of period		6 years 3 months 18 days	6 years 2 months 12 days
Options vested and expected to vest as of end period		6 years 3 months 18 days
Options exercisable as of end of period		5 years
Aggregate Intrinsic Value
Aggregate Intrinsic Value		$ 2	$ 28,778
Options vested and expected to vest as of December 31, 2021		2
Options exercisable as of end of period		$ 2

Stock-Based Awards - Additional

Stock-Based Awards - Additional Information (Detail) - USD ($) shares in Thousands	9 Months Ended
	Jun. 30, 2023	Sep. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested period	2020-12
Common Stock, Shares, Issued	21,056	20,791
Aggregate of unrecognized stock-based compensation cost	$ 69,426
Weighted average recognition period	2 years 4 months 24 days
Relative Total Stockholder Return Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	127%
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage	100%
Executive Officers [Member] | Relative Total Stockholder Return Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares range percentage	0%
Number of shares range percentage	150%

Stock-Based Awards - Summary _2

Stock-Based Awards - Summary of PSUs and rTSRUs Activity (Detail) shares in Thousands	9 Months Ended
	Jun. 30, 2023 $ / shares shares
PSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested, beginning balance | shares	101
Granted | shares	50
Vested | shares	(70)
Unvested, ending balance | shares	81
Weighted Average Grant Date Fair Value, Unvested beginning balance | $ / shares	$ 54.5
Weighted Average Grant Date Fair Value, Granted | $ / shares	47.24
Weighted Average Grant Date Fair Value, Vested | $ / shares	44.58
Weighted Average Grant Date Fair Value, Unvested ending balance | $ / shares	$ 58.58
rTSRUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested, beginning balance | shares	101
Granted | shares	50
Vested | shares	(70)
Unvested, ending balance | shares	81
Weighted Average Grant Date Fair Value, Unvested beginning balance | $ / shares	$ 36.14
Weighted Average Grant Date Fair Value, Granted | $ / shares	36.91
Weighted Average Grant Date Fair Value, Vested | $ / shares	23.89
Weighted Average Grant Date Fair Value, Unvested ending balance | $ / shares	$ 45.82

Stock-Based Awards - Summary _3

Stock-Based Awards - Summary of Restricted Stock Unit Activity (Detail) - Restricted Stock Units [Member] shares in Thousands	9 Months Ended
	Jun. 30, 2023 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested, beginning balance | shares	219
Granted | shares	277
Vested | shares	(56)
Cancelled | shares	(17)
Unvested, ending balance | shares	423
Weighted Average Grant Date Fair Value, Unvested beginning balance | $ / shares	$ 64.03
Weighted Average Grant Date Fair Value, Granted | $ / shares	45
Weighted Average Grant Date Fair Value, Vested | $ / shares	61.1
Weighted Average Grant Date Fair Value, Cancelled | $ / shares	54.92
Weighted Average Grant Date Fair Value, Unvested ending balance | $ / shares	$ 52.32

Stock-Based Awards - Stock-Base

Stock-Based Awards - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 6,998	$ 7,603	$ 21,500	$ 20,136
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	4,963	5,079	15,020	14,790
rTSRUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	440	207	1,447	1,171
Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	0	1,559	542	1,930
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	1,595	758	4,491	2,245
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	2,385	2,202	7,437	7,496
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 4,613	$ 5,401	$ 14,063	$ 12,640

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Apr. 30, 2023	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income Tax [Line Items]
Income tax (expense) benefit		$ (4,221)	$ 447	$ (4,231)	$ 447
Omers Royalty Sale Agreement [Member]
Income Tax [Line Items]
Proceeds from Royalties Received	$ 200,000