Zentalis Pharmaceuticals (ZNTL) 10-Q 10 Nov 21 2021 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2021	Nov. 09, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	001-39263
Entity Registrant Name	Zentalis Pharmaceuticals, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-3607803
Entity Address, Address Line One	530 Seventh Avenue,
Entity Address, Address Line Two	Suite 2201
Entity Address, City or Town	New York,
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10018
City Area Code	212
Local Phone Number	433-3791
Title of 12(b) Security	Common Stock,$0.001 par value per share
Trading Symbol	ZNTL
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		45,305,544
Entity Central Index Key	0001725160
Amendment Flag	false
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 40,807	$ 54,951
Marketable securities, available-for-sale	325,984	283,554
Accounts receivable from government grants, net	108	417
Prepaid expenses and other current assets	10,423	6,182
Restricted cash	243	0
Total current assets	377,565	345,104
Property and equipment, net	4,698	1,099
Operating lease right-of-use assets	693	2,520
Prepaid expenses and other assets	6,042	2,976
Goodwill	3,736	3,736
In-process research and development	0	8,800
Investment in Zentera Therapeutics	39,326	0
Restricted cash	3,021	1,320
Total assets	435,081	365,555
Current liabilities
Accounts payable	8,046	8,661
Accrued expenses	31,369	19,940
Total current liabilities	39,415	28,601
Deferred tax liability	1,670	2,480
Other long-term liabilities	0	1,097
Total liabilities	41,085	32,178
Commitments and contingencies
EQUITY
Preferred stock, $0.001 par value; 10,000,000 shares authorized; no shares issued and outstanding at September 30, 2021 and December 31, 2020	0	0
Common stock, $0.001 par value; 250,000,000 shares authorized; 45,198,528 and 41,040,286 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	45	41
Additional paid-in capital	702,855	509,339
Accumulated other comprehensive income	32	36
Accumulated deficit	(309,500)	(200,834)
Total stockholders’ equity	393,432	308,582
Noncontrolling interests	564	24,795
Total equity	393,996	333,377
Total liabilities and stockholders’ equity	$ 435,081	$ 365,555

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	250,000,000	250,000,000
Common stock issued (in shares)	45,198,528	41,040,286
Common stock outstanding (in shares)	45,198,528	41,040,286

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating Expenses
Research and development	$ 53,998	$ 24,670	$ 137,162	$ 55,380
General and administrative	8,872	10,097	31,187	23,162
Total operating expenses	62,870	34,767	168,349	78,542
Operating loss	(62,870)	(34,767)	(168,349)	(78,542)
Other Income (Expense)
Investment and other income, net	99	120	313	368
Gain on deconsolidation of Zentera, net of tax	51,582	0	51,582	0
Net loss before income taxes	(11,189)	(34,647)	(116,454)	(78,174)
Income tax expense (benefit)	(697)	18	(456)	18
Net loss	(10,492)	(34,665)	(115,998)	(78,192)
Net loss attributable to noncontrolling interests	(6,301)	(110)	(7,332)	(654)
Net loss attributable to Zentalis	$ (4,191)	$ (34,555)	$ (108,666)	$ (77,538)
Net loss per common share outstanding, basic (USD per share)	$ (0.09)	$ (0.91)	$ (2.59)	$ (3.21)
Net loss per common share outstanding, diluted (USD per share)	$ (0.09)	$ (0.91)	$ (2.59)	$ (3.21)
Common shares used in computing net loss per share, basic (in shares)	44,609	37,959	41,918	24,143
Common shares used in computing net loss per share, diluted (in shares)	44,609	37,959	41,918	24,143

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (10,492)	$ (34,665)	$ (115,998)	$ (78,192)
Other comprehensive income:
Currency translation effects	(45)	0	0	0
Unrealized gain (loss) on marketable securities	(17)	19	(4)	23
Total comprehensive loss	(10,554)	(34,646)	(116,002)	(78,169)
Net loss attributable to noncontrolling interests	(6,301)	(110)	(7,332)	(654)
Comprehensive loss attributable to Zentalis	$ (4,253)	$ (34,536)	$ (108,670)	$ (77,515)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating Activities:
Consolidated net loss	$ (115,998)	$ (78,192)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	335	127
IPR&D impairment	8,800	0
Recognized tax gain on IPR&D impairment	(2,462)	0
Gain on deconsolidation of Zentera, net of tax	(49,930)	0
Share-based compensation	27,266	15,259
Loss on disposal of equipment	15	0
Amortization of premiums on marketable securities, net	712	224
Changes in operating assets and liabilities:
Accounts receivable	309	18
Prepaid expenses and other assets	1,696	(5,784)
Accounts payable and accrued liabilities	12,310	9,049
Operating lease right-of-use assets and liabilities, net	(125)	(169)
Net cash used in operating activities	(117,072)	(59,468)
Investing activities:
Purchases of marketable securities	(280,285)	(304,085)
Proceeds from maturities of marketable securities	237,139	29,000
Deconsolidation of Zentera cash	(14,320)	0
Purchases of property and equipment	(3,916)	(97)
Net cash used in investing activities	(61,382)	(275,182)
Financing Activities:
Proceeds from issuance of common stock in initial public offering, net	0	172,482
Proceeds from issuance of common stock under equity incentive plans	4,031	0
Contributions from noncontrolling interest owners, net	0	18,424
Proceeds from issuance of common stock, net	162,223	155,899
Proceeds from the issuance of Series C convertible preferred units, net	0	14,228
Net cash provided by financing activities	166,254	361,033
Net increase/(decrease) in cash, cash equivalents and restricted cash	(12,200)	26,383
Cash, cash equivalents and restricted cash at beginning of period	56,271	67,489
Cash, cash equivalents and restricted cash at end of period	44,071	93,872
Supplemental disclosure of non-cash investing and financing activities:
Costs incurred in connection with initial public offering included in accounts payable and accrued expenses	0	594
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	40,807	92,552
Restricted cash	3,264	1,320
Total cash, cash equivalents and restricted cash reported in the Condensed Consolidated Statement of Cash Flows	$ 44,071	$ 93,872

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Members’/Stockholders’ Equity(Deficit) and Changes in Redeemable Convertible Preferred Units - USD ($) $ in Thousands	Total	IPO	Convertible Preferred Units	Class A Common Units	Class B Common Units	Common Stock	Common StockIPO	Common StockClass A Common Units	Common StockClass B Common Units	Additional Paid-in Capital	Additional Paid-in CapitalIPO	Accumulated Other Comprehensive Income	Accumulated Deficit	Noncontrolling Interests
Temporary equity, beginning balance at Dec. 31, 2019			$ 141,706
Temporary equity beginning balance (in shares) at Dec. 31, 2019			9,950,000
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of Series C convertible preferred units at $17.50 per unit net of issuance costs			$ 14,228
Issuance of Series C convertible preferred units at $17.50 per unit net of issuance costs (in shares)			867,000
Conversion of convertible preferred units to common stock	$ 155,934		$ (155,934)			$ 15				$ 155,919
Conversion of convertible preferred units to common stock (in shares)			(10,817,000)			(15,011,000)
Temporary equity, ending balance at Sep. 30, 2020			$ 0
Temporary equity ending balance (in shares) at Sep. 30, 2020			0
Beginning balance (in shares) at Dec. 31, 2019						0
Beginning balance at Dec. 31, 2019	(73,285)					$ 0				0		$ 0	$ (82,993)	$ 6,821
Common units, beginning balance (in shares) at Dec. 31, 2019								5,601,000	2,671,000
Common units, beginning balance at Dec. 31, 2019								$ 709	$ 2,178
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	15,259								$ 329	14,930
Other comprehensive income	23											23
Cancellation of profit interest awards, net (in shares)									(64,000)
Cancellation of restricted stock awards (in shares)						(7,000)
Issuance of common stock in connection with an offering, net of underwriting discounts, commissions and offering costs (in shares)				0	70,000	4,744,000	10,589,000
Issuance of common stock in connection with an offering, net of underwriting discounts, commissions and offering costs	155,305	$ 172,365				$ 5	$ 11			155,300	$ 172,354
Contributions from noncontrolling interest owners	18,424													18,424
Conversion of convertible preferred units to common stock (in shares)			10,817,000			15,011,000
Conversion of convertible preferred units to common stock	155,934		$ (155,934)			$ 15				155,919
Conversion of common and incentive units to common stock (in shares)						10,278,000		(5,601,000)	(2,607,000)
Conversion of common and incentive units to common and restricted stock	0					$ 10		$ (709)	$ (2,507)	3,206
Net loss attributable to noncontrolling interests	(654)									(187)				(467)
Net loss attributable to Zentalis	(77,538)												(77,538)
Common units, ending balance (in shares) at Sep. 30, 2020								0	0
Common units, ending balance at Sep. 30, 2020								$ 0	$ 0
Ending balance (in shares) at Sep. 30, 2020						40,615,000
Ending balance at Sep. 30, 2020	365,833					$ 41				501,522		23	(160,531)	24,778
Temporary equity, ending balance at Sep. 30, 2020			$ 0
Temporary equity ending balance (in shares) at Sep. 30, 2020			0
Beginning balance (in shares) at Jun. 30, 2020						35,878,000
Beginning balance at Jun. 30, 2020	237,925					$ 36				339,160		4	(125,976)	24,701
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	7,249									7,249
Other comprehensive income	19											19
Cancellation of restricted stock awards (in shares)						(7,000)
Issuance of common stock in connection with an offering, net of underwriting discounts, commissions and offering costs (in shares)						4,744,000
Issuance of common stock in connection with an offering, net of underwriting discounts, commissions and offering costs	155,305					$ 5				155,300
Net loss attributable to noncontrolling interests	(110)									(187)				77
Net loss attributable to Zentalis	(34,555)												(34,555)
Common units, ending balance (in shares) at Sep. 30, 2020								0	0
Common units, ending balance at Sep. 30, 2020								$ 0	$ 0
Ending balance (in shares) at Sep. 30, 2020						40,615,000
Ending balance at Sep. 30, 2020	$ 365,833					$ 41				501,522		23	(160,531)	24,778
Temporary equity beginning balance (in shares) at Dec. 31, 2020	0
Temporary equity ending balance (in shares) at Sep. 30, 2021	0
Beginning balance (in shares) at Dec. 31, 2020						41,040,000
Beginning balance at Dec. 31, 2020	$ 333,377					$ 41				509,339		36	(200,834)	24,795
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	27,266									27,266
Other comprehensive income	$ (4)											(4)
Issuance of common stock in connection with restricted stock unit vesting (in shares)	300,000					442,000
Deconsolidation event	$ (16,899)													(16,899)
Issuance of common stock upon exercise of options, net (in shares)	100,000					141,000
Issuance of common stock upon exercise of options, net	$ 3,486									3,486
Shares issued under employee stock purchase plan (in shares)						15,000
Shares issued under employee stock purchase plan	545									545
Cancellation of restricted stock awards (in shares)						(4,000)
Issuance of common stock in connection with an offering, net of underwriting discounts, commissions and offering costs (in shares)				0	0	3,565,000
Issuance of common stock in connection with an offering, net of underwriting discounts, commissions and offering costs	162,223					$ 4				162,219
Net loss attributable to noncontrolling interests	(7,332)													(7,332)
Net loss attributable to Zentalis	(108,666)												(108,666)
Ending balance (in shares) at Sep. 30, 2021						45,199,000
Ending balance at Sep. 30, 2021	$ 393,996					$ 45				702,855		32	(309,500)	564
Temporary equity ending balance (in shares) at Sep. 30, 2021	0
Beginning balance (in shares) at Jun. 30, 2021						41,315,000
Beginning balance at Jun. 30, 2021	$ 247,609					$ 41				529,019		94	(305,309)	23,764
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	7,656									7,656
Other comprehensive income	(62)											(62)
Issuance of common stock in connection with restricted stock unit vesting (in shares)						170,000
Deconsolidation event	(16,899)													(16,899)
Issuance of common stock upon exercise of options, net (in shares)						137,000
Issuance of common stock upon exercise of options, net	3,416									3,416
Shares issued under employee stock purchase plan (in shares)						15,000
Shares issued under employee stock purchase plan	545									545
Cancellation of restricted stock awards (in shares)						(3,000)
Issuance of common stock in connection with an offering, net of underwriting discounts, commissions and offering costs (in shares)						3,565,000
Issuance of common stock in connection with an offering, net of underwriting discounts, commissions and offering costs	162,223					$ 4				162,219
Net loss attributable to noncontrolling interests	(6,301)													(6,301)
Net loss attributable to Zentalis	(4,191)												(4,191)
Ending balance (in shares) at Sep. 30, 2021						45,199,000
Ending balance at Sep. 30, 2021	$ 393,996					$ 45				$ 702,855		$ 32	$ (309,500)	$ 564

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Members’/Stockholders’ Equity(Deficit) and Changes in Redeemable Convertible Preferred Units (Parenthetical) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)$ / shares
Conversion of common and incentive units to common and restricted stock | $	$ 0
Convertible Preferred Units
Par value per share (in dollars per share) | $ / shares	$ 17.50

Organization and Business

Organization and Business	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Business	Organization and Business Organization Zentalis Pharmaceuticals, Inc. (“Zentalis”, “We” or the “Company”) is a clinical-stage pharmaceutical company focused on discovering and developing clinically differentiated, novel small molecule therapeutics targeting fundamental biological pathways of cancer. The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. All of the Company’s tangible assets are held in the United States. The Company was formed and incorporated in the state of Delaware as Zeno Pharmaceuticals, Inc. on December 23, 2014. Effective November 21, 2017, Zeno Pharma, LLC was formed by the shareholders of Zeno Pharmaceuticals, Inc. On December 21, 2017, Zeno Pharmaceuticals, Inc. became a wholly owned subsidiary of Zeno Pharma, LLC. In connection with this restructuring, the rights and preferences of the Preferred Stock of Zeno Pharmaceuticals, Inc. were exchanged for preferred units with similar rights and preferences of Zeno Pharma, LLC. As part of the restructuring, the employees, consultants and board members of Zeno Pharmaceuticals, Inc. exchanged their equity grants in Zeno Pharmaceuticals, Inc. stock for Class B common units in Zeno Pharma, LLC. Additionally, existing common stockholders of Zeno Pharmaceuticals, Inc. exchanged their common stock for Class A common units in Zeno Pharma, LLC. All exchanges were made on a one-for-one basis. The restructuring was accounted for as a common control transaction. In December 2019, the Company was renamed to Zentalis Pharmaceuticals, LLC. Immediately prior to the effectiveness of the registration statement pertaining to the Company’s initial public offering (“IPO”) on April 2, 2020, the Company converted from a Delaware limited liability company into a Delaware corporation, and changed its name to Zentalis Pharmaceuticals, Inc. Pursuant to the statutory corporate conversion, all of the outstanding units of Zentalis Pharmaceuticals, LLC converted into shares of common stock of Zentalis Pharmaceuticals, Inc. based upon the value of Zentalis Pharmaceuticals, Inc. at the time of the IPO with a value implied by the price of the shares of common stock sold in the IPO. Based on the IPO price of $18.00 per share, the outstanding converted units converted into 25,288,854 shares of common stock (including 1,160,277 shares of restricted common stock). On April 7, 2020, the Company completed the IPO in which the Company issued and sold 10,557,000 shares of common stock (including 1,377,000 shares of common stock in connection with the full exercise of the underwriters’ option to purchase additional shares) at a public offering price of $18.00 per share. The Company’s aggregate gross proceeds from the sale of shares in the IPO, including the sale of shares pursuant to the full exercise of the underwriters’ option to purchase additional shares, was $190.0 million before fees and expenses of $17.6 million. Liquidity

Interim Unaudited Financial Sta

Interim Unaudited Financial Statements	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Interim Unaudited Financial Statements	Interim Unaudited Financial Statements Basis of Presentation The accompanying interim unaudited condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”) and with the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) related to a quarterly report on Form 10-Q. The year-end condensed consolidated balance sheet data was derived from the Company’s audited financial statements but does not include all disclosures required by U.S. GAAP. These condensed consolidated financial statements and notes thereto should be read in conjunction with the Company’s audited financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2020, filed with the SEC on March 25, 2021. The unaudited financial information for the interim periods presented herein reflects all adjustments which, in the opinion of management, are necessary for a fair presentation of the financial condition and results of operation for the periods presented, with such adjustments consisting only of normal recurring adjustments. The condensed consolidated financial statements include our accounts and our wholly-owned subsidiaries and variable interest entity (“VIE”) for which we are the primary beneficiary. All intercompany transactions and balances have been eliminated in consolidation. We evaluate our ownership, contractual and other interests in entities that are not wholly-owned by us to determine if these entities are VIEs, and, if so, whether we are the primary beneficiary of the VIE. In determining whether we are the primary beneficiary of a VIE and therefore required to consolidate the VIE, we apply a qualitative approach that determines whether we have both (1) the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and (2) the obligation to absorb losses of, or the rights to receive benefits from, the VIE that could potentially be significant to that VIE. We continuously assess whether we are the primary beneficiary of a VIE as changes to existing relationships or future transactions may result in the consolidation or deconsolidation, as the case may be, of such VIE. The equity method is used to account for investments in which we have the ability to exercise significant influence, but not control, over the investee. Such investments are recorded on the balance sheet, and the share of net income or losses of equity investments is recognized on a one quarter lag in investment and other income (expense), net. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in our consolidated financial statements and accompanying notes. On an ongoing basis, we evaluate our estimates and judgments, which are based on historical and anticipated results and trends and on various other assumptions that management believes to be reasonable under the circumstances. By their nature, estimates are subject to an inherent degree of uncertainty and, as such, actual results may differ from management’s estimates. Though the impact of the COVID-19 pandemic to our business and operating results presents additional uncertainty, we continue to use the best information available to inform our critical accounting estimates. Significant Accounting Policies During the nine months ended September 30, 2021, there have been no changes to the Company’s significant accounting policies as described in its Annual Report on Form 10-K for the fiscal year ended December 31, 2020 outside of the equity method accounting for investments and adoption and pending adoption of recent accounting pronouncements mentioned below. Equity Method Accounting We have significant influence, but not a controlling interest, in Zentera. From the deconsolidation of Zentera during July 2021 prospectively, this investment is accounted for using the equity method. Our share of earnings or losses of the investment entity are reported on the consolidated statement of operations through investment and other income, net, with a corresponding increase or decrease to the equity investment carried on the statement of financial position. This information is generally not received sufficiently timely for us to record our portion of earnings or loss in the current financial statements and therefore we report our portion of earnings or loss on a one quarter lag. Adoption and Pending Adoption of Recent Accounting Pronouncements The following table provides a brief description of recently issued accounting standards, those adopted in the current period and those not yet adopted: Standard Description Effective Date Effect on the Financial In January 2020, the FASB issued ASU 2020-01, Investments – Equity Securities (Topic 321) This standard clarifies the interaction between accounting standards related to equity securities (ASC 321), equity method investments (ASC 323), and certain derivatives (ASC 815). January 1, 2021 As of January 1, 2021, we did not hold equity securities, equity method investments or derivatives. The impact of this new accounting guidance in 2021 did not have a material impact to our consolidated financial statements at the time of adoption. As of July 2021, we hold an equity method investment which is accounted for under ASC 323. The investment is recorded on the consolidated statement of financial position at fair value as of the date of deconsolidation. The Company’s share of earnings or losses of the investment entity are reported on the consolidated statement of operations through investment and other income, net with a corresponding increase or decrease to the equity investment.

Significant Transactions

Significant Transactions	9 Months Ended
	Sep. 30, 2021
Equity Method Investments and Joint Ventures [Abstract]
Significant Transactions	Significant Transactions Zentera Therapeutics In May 2020, we became a majority common shareholder of Zentera Therapeutics, Ltd., a Shanghai-based clinical-stage biopharmaceutical company focused on developing cancer therapeutics (“Zentera”), concurrent with its Series A convertible preferred stock offering. The financial position and results of operations of Zentera have been included in our consolidated financial statements from the date of the initial investment as a result of our control of the entity. In July 2021, Zentera completed a Series B convertible preferred stock offering which diluted our investment to a position of less than majority owned. Upon review of the facts and circumstances, together with the authoritative accounting literature, we determined that consolidation of Zentera is no longer appropriate. After the July 2021 Series B convertible preferred offering in which we did not participate, our review concluded that we ceased to have a controlling financial interest in Zentera, an additional board member was added to the Zentera board of directors and we concluded that we no longer have the power to direct the activities that most significantly affect Zentera’s economic performance nor are we the primary beneficiary of Zentera. Beginning in July 2021, the financial position and results of operations of Zentera are no longer included in our consolidated financial statements. An equity method investment of $39.3 million was recorded on our balance sheet representing the fair value of our common stock investment using the backsolve method with consideration for a lack of marketability at the time of deconsolidation. A corresponding deferred tax liability of $1.7 million representing the tax impact of the unrealized gain on deconsolidation was recorded during the three months ended September 30, 2021. A gain of $51.6 million, measured as the difference between the fair value of our retained noncontrolling interest together with the carrying amount of the Zentera noncontrolling interest, and the carrying amount of Zentera’s assets and liabilities was recognized during the third quarter of 2021. In May 2020, each of our subsidiaries Zeno Alpha, Inc., K-Group Alpha, Inc., Zeno Management Inc., and K-Group Beta, Inc. entered into a collaboration and royalty-bearing license agreement with Zentera, which we refer to as the “Zentera Sublicenses,” pursuant to which we collaborate with Zentera on the development and commercialization of ZN-c3, ZN-c5 and ZN-d5, respectively, in the People’s Republic of China, Macau, Hong Kong and Taiwan, which is referred to as the “Zentera Collaboration Territory.” Under each Zentera Sublicense, Zentera will lead development, and upon regulatory approval, the commercialization, of the collaboration products in the Zentera Collaboration Territory.

Business Combinations

Business Combinations	9 Months Ended
	Sep. 30, 2021
Business Combination and Asset Acquisition [Abstract]
Business Combinations	Business Combinations Kalyra Pharmaceuticals, Inc. On December 21, 2017, we acquired $4.5 million of Kalyra’s Series B Preferred Stock representing a 25% equity interest in Kalyra for purposes of entering the analgesics therapeutic research space. The acquisition price was paid entirely in cash. In accordance with the authoritative guidance, we concluded that Kalyra is a business consisting of inputs, employees, intellectual property and processes capable of producing outputs. Additionally, we have concluded that Kalyra is a variable interest entity, we are the primary beneficiary and have the power to direct the activities that most significantly affect Kalyra’s economic performance through common management and our board representation. Prior to the change of control, the Company and Kalyra transacted for the delivery of research and development services and support. The financial position and results of operations of Kalyra have been included in our consolidated financial statements from the date of the initial investment. Pursuant with authoritative guidance, we have recorded the identifiable assets, liabilities and noncontrolling interests in the VIE at their fair value upon initial consolidation. The identified goodwill is comprised of the workforce and expected synergies from combining the entities. During the third quarter of 2021, Kalyra determined that they will no longer pursue the development of Kalyra’s lead product candidate and ceased the associated clinical trial. The in-process research and development costs (“IPR&D”) recorded on Kalyra’s balance sheet exclusively relates to this candidate. Management recorded an impairment charge of $8.8 million within the research and development expense line item on the consolidated statement of operations during the third quarter of 2021, which resulted in a reduction of the IPR&D asset from $8.8 million to zero. The impairment of IPR&D resulted in a reversal of the associated deferred tax liability of $2.4 million during the third quarter of 2021. Total assets and liabilities of Kalyra as of September 30, 2021 and December 31, 2020 are as follows (in thousands): September 30, December 31, 2021 2020 Cash and cash equivalents $ 556 $ 417 Other current assets 107 82 In-process research and development — 8,800 Goodwill 3,736 3,736 Accounts payable and accrued expenses 124 83 Deferred tax liability — 2,463 Noncontrolling interests $ 564 $ 6,705 The liabilities recognized as a result of consolidating Kalyra do not represent additional claims on our general assets. Pursuant to the authoritative guidance, the equity interest in Kalyra not owned by Zentalis is reported as a noncontrolling interest on our condensed consolidated balance sheets. The following is a reconciliation of equity (net assets) attributable to the noncontrolling interest (in thousands): September 30, 2021 Noncontrolling interest at beginning of period $ 6,705 Net loss attributable to noncontrolling interest (6,141) Noncontrolling interest at end of period $ 564

Fair Value Measurement

Fair Value Measurement	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurement	Fair Value Measurement Available-for-sale marketable securities consisted of the following (in thousands): September 30, 2021 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper 239,391 23 (2) 239,412 Corporate Debt Securities 10,145 — (3) 10,142 US Government Agencies 35,731 6 — 35,737 US Treasury 40,685 9 (1) 40,693 325,952 38 (6) 325,984 December 31, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper 147,382 14 (8) 147,388 Corporate Debt Securities 23,576 1 (6) 23,571 US Government Agencies 81,455 32 (1) 81,486 US Treasury 31,105 4 — 31,109 283,518 51 (15) 283,554 The Company regularly reviews the securities in an unrealized loss position and evaluates the current expected credit loss by considering factors such as the severity of the impairment, changes in underlying credit ratings, forecasted recovery, our intent to sell or the likelihood that we would be required to sell the investment before its anticipated recovery in market value and the probability that the scheduled cash payments will continue to be made. Based on our review of these marketable securities, we believe none of the unrealized loss is as a result of a credit loss as of September 30, 2021, because we do not intend to sell these securities and it is not more-likely-than-not that we will be required to sell these securities before the recovery of their amortized cost basis. Contractual maturities of available-for-sale debt securities are as follows (in thousands): September 30, 2021 December 31, 2020 Estimated Fair Value Due within one year $ 315,988 $ 247,455 After one but within five years 9,996 36,099 $ 325,984 $ 283,554 The following table summarizes, by major security type, our cash equivalents and available-for-sale marketable securities that are measured at fair value on a recurring basis and are categorized using the fair value hierarchy (in thousands): September 30, 2021 December 31, 2020 Level 1 Level 2 Total estimated fair value Level 1 Level 2 Total estimated fair value Cash equivalents: Money market funds 25,648 — 25,648 $ 24,016 $ — $ 24,016 Corporate Debt Securities — — — — 4,999 4,999 Total cash equivalents: 25,648 — 25,648 24,016 4,999 29,015 Available-for-sale marketable securities: Commercial paper — 239,412 239,412 — 147,388 147,388 Corporate Debt Securities — 10,142 10,142 — 23,571 23,571 US Government Agencies — 35,737 35,737 — 81,486 81,486 US Treasury securities 40,693 — 40,693 31,109 — 31,109 Total available-for-sale marketable securities: 40,693 285,291 325,984 31,109 252,445 283,554 Total assets measured at fair value 66,341 285,291 351,632 $ 55,125 $ 257,444 $ 312,569 There were no transfers between Level 1 and Level 2 of the fair value hierarchy during the nine months ended September 30, 2021. We had no instruments that were classified within Level 3 as of September 30, 2021 or December 31, 2020.

Prepaid Expenses and Other Asse

Prepaid Expenses and Other Assets	9 Months Ended
	Sep. 30, 2021
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid Expenses and Other Assets	Prepaid Expenses and Other Assets Prepaid expenses and other assets consisted of the following (in thousands): September 30, December 31, 2021 2020 Prepaid insurance $ 1,661 $ 1,021 Prepaid software licenses and maintenance 207 563 Foreign R&D credit refund 1,345 692 Prepaid research and development expenses 9,136 5,963 Interest receivable 288 478 Zentera receivable 2,940 — Other prepaid expenses 888 441 Total prepaid expenses and other assets 16,465 9,158 Less long-term portion 6,042 2,976 Total prepaid expenses and other assets, current $ 10,423 $ 6,182

Property and Equipment, net

Property and Equipment, net	9 Months Ended
	Sep. 30, 2021
Property, Plant and Equipment [Abstract]
Property and Equipment, net	Property and Equipment, net Property and equipment, net consisted of the following (in thousands): September 30, December 31, 2021 2020 Computer and Office Equipment $ 563 $ 529 Lab Equipment 1,883 424 Leasehold Improvements 49 49 Construction in Progress 2,787 347 Subtotal 5,282 1,349 Accumulated depreciation and amortization (584) (250) Property and equipment, net $ 4,698 $ 1,099 Depreciation and amortization expense for the three months ended September 30, 2021 and 2020 was approximately $137 thousand and $51 thousand, respectively. Depreciation and amortization expense for the nine months ended September 30, 2021

Accrued Expenses

Accrued Expenses	9 Months Ended
	Sep. 30, 2021
Payables and Accruals [Abstract]
Accrued Expenses	Accrued Expenses Accrued expenses consist of the following (in thousands): September 30, December 31, 2021 2020 Accrued research and development expenses $ 19,589 $ 11,947 Accrued employee expenses 7,883 5,649 Accrued general and administrative expenses 2,268 996 Lease liability 862 902 Taxes payable 767 410 Other $ — $ 36 Total accrued expenses $ 31,369 $ 19,940

Convertible Preferred Units

Convertible Preferred Units	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Convertible Preferred Units	Convertible Preferred Units Series A Convertible Preferred Units In September 2015, Zeno Pharmaceuticals, Inc. entered into a Series A Preferred Stock Purchase Agreement (the “Series A Preferred Agreement”). Under the terms of the Series A Preferred Agreement, Zeno Pharmaceuticals, Inc. issued 1,293,104 shares of Series A convertible preferred stock at $11.60 per share for gross proceeds of $15.0 million. The net proceeds of this financing were $14.9 million after issuance costs of $0.1 million. In February and March 2016, Zeno Pharmaceuticals, Inc. issued an aggregate of 286,205 additional shares of Series A convertible preferred stock at $11.60 per share for additional gross proceeds of $3.3 million. The issuance costs of this additional financing were approximately thirty-nine thousand dollars. All Series A convertible preferred stock issued and outstanding by Zeno Pharmaceuticals, Inc. was converted into Series A convertible preferred units of Zentalis Pharmaceuticals, LLC in conjunction with the corporate restructuring and merger. Series B Convertible Preferred Units In December 2017, Zentalis Pharmaceuticals, LLC entered into a Series B Preferred Unit Purchase Agreement (the “Series B Preferred Agreement”). Under the terms of the Series B Preferred Agreement, Zentalis Pharmaceuticals, LLC issued 2,735,320 Series B preferred units at $12.43 per unit for gross proceeds of $34.0 million. The net proceeds of this financing were $32.1 million after issuance costs of $1.9 million. In January and August 2018, Zentalis Pharmaceuticals, LLC issued an aggregate of 788,419 additional shares of Series B preferred units at $12.43 per unit for additional gross proceeds of $9.8 million. The net proceeds of this additional financing were $9.5 million after issuance costs of $0.3 million. Series C Convertible Preferred Units In September 2019, Zentalis Pharmaceuticals, LLC entered into a Series C Preferred Unit Purchase Agreement (the “Series C Preferred Agreement”). Under the terms of the Series C Preferred Agreement, Zentalis Pharmaceuticals, LLC issued 4,847,106 units of Series C convertible preferred units at $17.50 per unit for gross proceeds of $84.8 million. The net proceeds of this financing were $81.9 million after issuance costs of $2.9 million. In February 2020, Zentalis Pharmaceuticals, LLC issued 867,194 additional units of Series C preferred units under the Series C Preferred Agreement. The units were issued for $17.50 per unit for gross proceeds of $15.2 million. The net proceeds of this financing were $14.2 million after issuance costs of $1.0 million. There were no authorized, issued, or outstanding shares of convertible preferred units at September 30, 2021 and December 31, 2020. During 2020, we reclassified the convertible preferred units from members’ equity to temporary equity because, in conjunction with the Series C convertible preferred units issuance, all units were now deemed to contain contingent liquidation features that are not solely within our control. During the year ended December 31, 2020, we did not adjust the carrying values of the convertible preferred units to the deemed redemption values of such units since a liquidation event was not probable. Dividends Dividends are payable if and when declared by the Board of Directors. No dividends have been declared through September 30, 2021. Conversion Each Series A preferred unit, Series B preferred unit and Series C preferred unit was convertible at the option of the holder thereof, at any time after the issuance of such unit, into Class A common units at a conversion price equal to the original purchase price (subject to anti-dilution adjustments, discussed below) which was $11.60, $12.43 and $17.50 per unit, respectively. The convertible preferred units automatically converted at the then applicable conversion rate upon the closing of a firm commitment underwritten public offering of shares of a successor corporations’ common stock, at a public offering price per share of equal to or greater than the Series C original purchase price (as adjusted for any stock splits, stock dividends, combinations or other similar recapitalization) resulting in aggregate gross cash proceeds of at least $75.0 million (a “Qualified IPO”). Additionally, the convertible preferred unit would have automatically converted into common stock, at the then applicable conversion rate, upon written consent of a majority of the then outstanding Series A, Series B and Series C convertible preferred units (voting as a separate class on an as converted to Common Unit basis). In conjunction with our IPO on April 2, 2020, which constituted a Qualified IPO, all convertible preferred units were converted to common stock. Anti-dilution protection The holders of the convertible preferred units had proportional anti-dilution protection for unit splits, unit dividends and similar recapitalizations. Subject to certain exclusions, anti-dilution price protection for additional sales of securities by us for consideration per unit less than the applicable conversion price per unit of any series of convertible preferred stock, was on a broad-based weighted average basis. Protective rights The holders of the convertible preferred units had certain protective rights, including, without limitation, regarding the authorization, alteration, redemption, or sale of Class B common units; commencement of a liquidation or deemed liquidation event; entrance into a joint venture or partnership; any incurrence of indebtedness; certain transactions that exceed a certain dollar threshold; changes to our governing documents; or the declaration of any dividends. Such actions were required to be approved by a majority of the then outstanding Series A, Series B and Series C convertible preferred unit holders (voting as a single class and on an as-converted basis), as specified in the amended and restated LLC agreement. An increase or decrease in the authorized number of Directors constituting the Board or the creation of a membership interest or equity security senior to or pari passu with Series C convertible preferred units was required to be approved by a majority of the then outstanding Series C convertible preferred Units (voting as a separate class on an as converted basis). Redemption The Series A, Series B and Series C convertible preferred units were not redeemable except in the event of certain effected deemed liquidation events. As of immediately prior to our IPO on April 2, 2020, we had classified convertible preferred units as temporary equity in accordance with authoritative guidance for the classification and measurement of potentially redeemable securities whose redemption is based upon certain change in control events outside of our control, including liquidation, sale or transfer of control of the Company. We did not adjust the carrying value of the convertible preferred units to the deemed redemption values of such units since a liquidation event was not probable. Liquidation preference In the event of the dissolution, liquidation, merger or winding up of the Company, the holders of Series C convertible preferred units were entitled to receive, on a pro rata basis in respect of each such Series C convertible preferred unit, a preference amount of $17.50 per Series C convertible unit (as adjusted for any unit splits, dividends, combinations, recapitalizations or the like). Subsequent to the payment of the Series C convertible preferred unit preferences, Series A and Series B convertible preferred units were entitled to receive, on a pro rata basis in respect of each convertible preferred unit in proportion to the relative preference amount of each preferred unit, a preference amount of $11.60 and $12.43 per unit of Series A and Series B convertible preferred units (as adjusted for any units splits, dividend, combinations, recapitalizations of the like), respectively. Subsequent to the payment of the Series C, Series A and Series B convertible preferred unit preferences, Series A, Series B and Series C convertible preferred units are entitled to receive, on an as converted to common unit pro rata basis, an amount equal to distributions made to Class A common units prior to all unit classes sharing in distributions on a pro rata basis. Thereafter, Series A, Series B and Series C convertible preferred units and Series A and Series B common units were entitled to receive the remaining assets of the Company available for distribution to its unit holders pro rata based on the number of common units held by each holder, treating for these purposes as if all units had been converted to common. Voting Rights The holders of all units other than Class B common units that were unvested were to vote together as a single class. Each holder of Series A, Series B and Series C convertible preferred units were entitled to the number of votes calculated on an as converted to Class A common unit basis.

Members_ Equity

Members’ Equity	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Members’ Equity	Members’ Equity In November 2017, Zentalis Pharmaceuticals, LLC was formed in the state of Delaware. In conjunction with a corporate restructuring, Zeno Pharmaceuticals, Inc., a Delaware corporation formed in 2014, was acquired by the Company pursuant to a merger agreement and became a wholly owned subsidiary of the Company. Per the terms of the merger agreement, each share of Zeno Pharmaceuticals, Inc. common stock issued and outstanding immediately prior to the effective time of the merger was converted into the right to receive one Class A common unit and each share of Zeno Pharmaceuticals, Inc. Series A preferred stock issued and outstanding immediately prior to the effective date of the merger converted into the right to receive one Series A preferred unit. As of the effective time of the merger agreement, all outstanding options to purchase shares of Zeno Pharmaceuticals, Inc. common stock were cancelled and replaced with profits interest awards in the LLC. In connection with the December 2017 corporate restructuring, we amended and restated the LLC agreement, and as amended, the capital units of the Company consisted of 1,638,000 authorized Series A preferred units, 3,621,000 authorized Series B preferred units, 15,000,000 authorized Class A common units and 872,620 authorized Class B common units. Class A Common Units In conjunction with the corporate restructuring in December 2017, 5,187,554 shares of common stock issued and outstanding and 406,831 shares of common stock subject to future vesting provisions of Zeno Pharmaceuticals, Inc. were converted into an equal number of Class A common units of Zentalis Pharmaceuticals, LLC. In September 2019, the number of authorized Class A common units was increased to 20,000,000. During the nine months ended September 30, 2021 and 2020, we did not issue any Class A common units. As of September 30, 2021 and 2020, there were no Class A common units subject to future vesting conditions. Class B Common Units In conjunction with the corporate restructuring in December 2017, 703,000 options exercisable into Zeno Pharmaceuticals, Inc. common stock were converted into an equal number of Class B Common Units of Zentalis Pharmaceuticals, LLC. In September 2019, the number of authorized Class B common units was increased to 3,458,522. IPO and Follow-on Offerings On April 2, 2020 and immediately prior to the effectiveness of the Company’s IPO, Zentalis Pharmaceuticals, LLC converted from a Delaware limited liability company into a Delaware corporation pursuant to a statutory conversion, and changed its name to Zentalis Pharmaceuticals, Inc. In order to consummate the corporate conversion, a certificate of conversion was filed with the Secretary of State of the State of Delaware. All of the outstanding units of Zentalis Pharmaceuticals, LLC converted into shares of common stock of Zentalis Pharmaceuticals, Inc. based upon the value of Zentalis Pharmaceuticals, Inc. at the time of the IPO with a value implied by the price of the shares of common stock sold in the IPO. No cash or fractional shares of common stock were issued in connection with the corporate conversion. Based on the IPO price of $18.00 per share of common stock, all of the outstanding units converted into an aggregate of 25,288,854 shares of common stock (including 1,160,277 shares of restricted common stock). In connection with the completion of the IPO, the board and stockholders approved the certificate of incorporation to provide for 250,000,000 authorized shares of common stock with a par value of $0.001 per share and 10,000,000 authorized shares of preferred stock with a par value of $0.001 per share. On April 7, 2020, the Company completed an IPO in which the Company issued and sold 10,557,000 shares of common stock (including 1,377,000 shares of common stock in connection with the full exercise of the underwriters’ option to purchase additional shares) at a price of $18.00 per share. The Company’s aggregate gross proceeds from the sale of shares in the IPO, including the sale of shares pursuant to the full exercise of the underwriters’ option to purchase additional shares, was $190.0 million before fees and expenses of $17.6 million. On August 3, 2020, the Company completed a follow-on offering in which the Company issued and sold 4,743,750 shares of common stock (including 618,750 shares of common stock in connection with the full exercise of the underwriters’ option to purchase additional shares) at a public offering price of $35.00 per share. The Company’s aggregate gross proceeds from the sale of shares in the follow-on offering, including the sale of shares pursuant to the full exercise of the underwriters’ option to purchase additional shares, was $166.0 million before fees and expenses of $10.8 million. On July 1, 2021, the Company completed a follow-on offering in which the Company issued and sold 3,565,000 shares of common stock (including 465,000 shares of common stock in connection with the full exercise of the underwriters’ option to purchase additional shares) at a public offering price of $48.50 per share. The Company’s aggregate gross proceeds from the sale of shares in the follow-on offering, including the sale of shares pursuant to the full exercise of the underwriters’ option to purchase additional shares, was $172.9 million before fees and expenses of $10.7 million. Share-based Compensation In the Company’s 2017 Profits Interest Plan (“the Plan”) as approved and adopted by the Board of Directors on December 21, 2017, the Company was authorized to issue up to 3,458,522 shares of Class B common units, (“profits interest award units”), subject to restrictions as described in the Plan. In April 2020, the Plan was terminated and the Company’s board of directors adopted, and the Company’s stockholders approved the 2020 Incentive Award Plan (“the 2020 Plan”), which became effective upon the corporate conversion and allows for grants to selected employees, consultants and non-employee members of the Board of Directors. We currently grant stock options and restricted stock units under the 2020 Plan. The number of common shares available for issuance under the 2020 Plan is the sum of (1) 5,600,000 shares of common stock; plus (2) any shares forfeited from the unvested restricted shares of our common stock issued upon conversion of unvested Class B common units (up to 1,250,000 shares); plus (3) an annual increase on the first day of each fiscal year beginning with the fiscal year ending December 31, 2021 and continuing to, and including, the fiscal year ending December 31, 2030, equal to the lesser of (a) 5% of the shares of common stock outstanding on the final day of the immediately preceding calendar year and (b) such smaller number of shares as determined by our board of directors. At September 30, 2021, 4,418,484 shares were subject to outstanding awards and 2,237,052 shares were available for future grants of share-based awards. Total share-based compensation expense related to share based awards was comprised of the following (in thousands): Three Months Ended Nine Months Ended 2021 2020 2021 2020 Research and development expense $ 3,697 $ 2,180 $ 10,746 $ 4,606 General and administrative expense 3,959 5,069 16,520 10,653 Total share-based compensation expense $ 7,656 $ 7,249 $ 27,266 $ 15,259 Prior to the deconsolidation during the third quarter of 2021, total share-based compensation expense includes $138 thousand of share-based compensation expense for employees, consultants and directors of Zentera, for the nine months ended September 30, 2021, compared to $187 thousand for the same period in 2020. Share-based compensation expense by type of share-based award (in thousands): Three Months Ended Nine Months Ended 2021 2020 2021 2020 Profit Interest Award Units $ — $ — $ — $ 329 Stock Options 5,596 2,212 14,267 3,814 Employee Stock Purchase Plan 103 — 213 — RSAs and RSUs 1,957 5,037 12,786 11,116 $ 7,656 $ 7,249 $ 27,266 $ 15,259 The fair value of the profits interest awards is estimated using an option pricing model with the following assumptions: Nine Months Ended 2020 Members’ equity value (in thousands) $ 271,207 Threshold amounts (in thousands) $ 309,824 Risk free interest rate 1.5 % Volatility 75.0 % Time to liquidity (in years) 1.1 Lack of marketability discount 26.5 % Grant date fair value $ 3.06 The Black-Scholes option pricing model is used to estimate the fair value of each profits interest award on the date of grant. The members’ equity value was based on a recent enterprise valuation analysis performed. The threshold amounts are based on the discretion of the Board of Directors at the time of grant. The expected life of the Class B Common Unit awards granted during the period presented was determined based on an expected liquidation event under the plan. We apply the risk-free interest rate based on the U.S. Treasury yield in effect at the time of the grant consistent with the life of the award. The expected volatility is based on a peer group in the industry in which the Company does business consistent with the expected time to liquidity. The dividend yield was set at zero as the underlying security does not and is not expected to pay a dividend. The Finnerty model and the Asian Protective Put Model methods were used to estimate the discount for lack of marketability inherent to the awards. The Class B common units issued have been classified as equity awards, and share-based compensation expense is based on the grant date fair value of the award. During the nine months ended September 30, 2021 and 2020, we issued zero and 70,000 Class B common units, respectively. As of September 30, 2021 and December 31, 2020, there were no Class B common units outstanding. Stock Options and Restricted Stock Units The exercise price of stock options granted is equal to the closing price of the common stock on the date of grant. The fair value of each option award is estimated on the date of grant using the Black-Scholes model. Due to the Company’s limited operating history and a lack of company specific historical and implied volatility data, the Company estimates expected volatility based on the historical volatility of a group of similar companies that are publicly traded. The historical volatility data was computed using the daily closing prices for the selected companies’ shares during the equivalent period of the calculated expected term of the stock-based awards. The Company uses the “simplified method” for estimating the expected term of employee options, whereby the expected term equals the arithmetic average of the vesting term and the original contractual term of the option (generally 10 years). The risk-free interest rate is based on the U.S. Treasury yield for a period consistent with the expected term of the option in effect at the time of the grant. The Company has not issued any dividends and does not expect to issue dividends over the life of the options. As a result, the Company has estimated the dividend yield to be zero. The fair value of the stock options granted during the nine months ended September 30, 2021 and September 30, 2020 was determined with the following assumptions: September 30, 2021 September 30, 2020 Expected volatility 73.9% - 76.6% 76.6% - 78.2% Average expected term (in years) 5.2 - 6.2 5.7 - 6.0 Risk-free interest rate 0.5% - 1.1% 0.4% - 0.5% Expected dividend yield — % — % Employee Stock Purchase Plan The weighted average assumptions used to estimate the fair value of stock purchase rights under the employee stock purchase plan (“ESPP”) are as follows: Ended September 30, 2021 2020 ESPP Volatility 64 % — Expected term (years) 0.5 — Risk free rate — % — Expected dividend yield — — Under the terms of the ESPP, the Company’s employees may elect to have up to 20% of their compensation, up to a maximum of $21,250 per calendar year, withheld to purchase shares of the Company’s common stock for a purchase price equal to 85% of the lower of the fair market value per share (at closing) of the Company’s common stock on (i) the first trading day of a six-month offering period, or (ii) the applicable purchase date, defined as the last trading day of the six-month offering period. Total unrecognized estimated compensation cost by type of award and the weighted average requisite service period over which such expense is expected to be recognized (in thousands, unless otherwise noted): September 30, 2021 Unrecognized Remaining Stock options $ 65,008 3.05 RSAs $ 1,472 1.84 RSUs $ 7,793 2.29 ESPP $ — 0 During the nine months ended September 30, 2021, we issued 0.1 million shares of common stock in connection with the exercises of stock options. For the nine months ended September 30, 2021, 0.3 million shares of

Commitment and Contingencies

Commitment and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Contingencies From time to time, we may be involved in various disputes, including lawsuits and claims arising in the ordinary course of business, including actions with respect to intellectual property, employment, and contractual matters. Any of these claims could subject us to costly legal expenses. The Company records a liability in its consolidated financial statements for these matters when a loss is known or considered probable and the amount can be reasonably estimated. The Company reviews these estimates each accounting period as additional information is known and adjusts the loss provision when appropriate. If a matter is both probable to result in a liability and the amounts of loss can be reasonably estimated, the Company estimates and discloses the possible loss or range of loss to the extent necessary to make the consolidated financial statements not misleading. If the loss is not probable or cannot be reasonably estimated, a liability is not recorded in our consolidated financial statements. While we do generally believe that we have adequate insurance to cover many different types of liabilities, our insurance carriers may deny coverage, or our policy limits may be inadequate to fully satisfy any damage awards or settlement. If this were to happen, the payment of any such awards could have a material adverse effect on our consolidated results of operations and financial position. Additionally, any such claims, whether or not successful, could damage our reputation and business. We are currently not a party to any legal proceedings. Leases Our commitments include payments related to operating leases. Approximate annual future minimum operating lease payments as of September 30, 2021 are as follows (in thousands): Year Operating Leases 2021 $ 271 2022 637 Total minimum lease payments: 908 Less: imputed interest (46) Total operating lease liabilities 862

Net Loss Per Common Share_Class

Net Loss Per Common Share/Class A Common Unit	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Loss Per Common Share/Class A Common Unit	Net Loss Per Common Share/Class A Common Unit Basic and diluted net loss per common share/Class A common unit were calculated as follows (in thousands except per share and per unit amounts): Three Months Ended Nine Months Ended 2021 2020 2021 2020 Numerator: Net loss attributable to Zentalis $ (4,191) $ (34,555) $ (108,666) $ (77,538) Denominator: Weighted average number of common shares outstanding, basic and diluted 44,609 37,959 41,918 24,143 Net loss per common share $ (0.09) $ (0.91) $ (2.59) $ (3.21) Our potential and dilutive securities, which include outstanding stock options, unvested RSAs and unvested RSUs have been excluded from the computation of diluted net loss per common share as the effect would be anti-dilutive. The following common stock equivalents have been excluded from the calculations of diluted net loss per common share because their inclusion would be antidilutive (in thousands). September 30, 2021 2020 Outstanding stock options 4,055 2,783 Unvested RSAs 447 845 Unvested RSUs 364 1,102 4,866 4,730

Related Party Disclosures

Related Party Disclosures	9 Months Ended
	Sep. 30, 2021
Related Party Transactions [Abstract]
Related Party Disclosures	Related Party Disclosures Kalyra Pharmaceuticals, Inc. and Recurium IP Holdings, LLC On December 21, 2017, we acquired 17,307,692 shares of Series B preferred stock of Kalyra Pharmaceuticals, Inc. for a per share price of twenty-six cents ($0.26) or approximately $4.5 million. The management team and stockholders of Kalyra are also stockholders of the Company. Prior to the investment, we entered into a license agreement and a master services agreement with Kalyra. The license agreement was signed and commenced on December 31, 2014 for the exclusive rights to develop and commercialize products derived from Kalyra’s technology in the initial area of oncology. The license agreement and all rights were subsequently sold from Kalyra to Recurium IP Holdings, LLC (“Recurium IP”), an entity with common ownership to Kalyra prior to the Zentalis investment. Under the agreement, we have agreed to make payments to Recurium IP based on specific milestones. In addition, the Company shall pay mid to high-single digit percentage royalties on net product sales to Recurium IP and sublicense fees on any consideration paid to us by a sublicensor. All payments are based on Recurium Equity, LLC’s, an affiliate company of Recurium IP, equity ownership stake in us as of December 2020. The license agreement will terminate upon the later of the last expiration of the patent rights or 15 years from the date of commencement. For the nine months ended September 30, 2021 and 2020 , we paid $10.0 million and zero, respectively, in milestone payments to Recurium IP in connection with the commencement of Phase 2 trials for ZN-c3 and ZN-c5. The Master Services Agreement (“MSA”) was entered into in January 2015 and states that Kalyra may provide research and development services to us and that we shall reimburse such expenses on a time and materials basis based on the initial statements of work. For each of the three months ended September 30, 2021 and 2020, we did not incur any expense with Kalyra. For the nine months ended September 30, 2021 and 2020, we incurred approximately zero and seventeen thousand dollars of expense with Kalyra, respectively, that was eliminated in consolidation for research and development services provided. As of September 30, 2021 and 2020, there was no balance due to Kalyra. We entered into an Intercompany Services Agreement (“ISA”) with Kalyra in January 2018 which states that we may provide research and development services to Kalyra and that Kalyra shall reimburse such expenses on a time and materials basis. For the three and nine months ended September 30, 2021 and 2020, we provided immaterial research and development services to Kalyra that were eliminated in consolidation, respectively. As of September 30, 2021 and 2020, an immaterial amount was due from Kalyra and eliminated in consolidation, respectively. Tempus Kimberly Blackwell, M.D., is a member of the Company's board of directors and is also the Chief Medical Officer of Tempus Labs, Inc. ("Tempus"). The Company entered into a Master Services Agreement with Tempus in December 2020 to provide data licensing and research services. There were $1.0 million and zero fees incurred for services performed by Tempus for the nine months ended September 30, 2021 and 2020, respectively. Zentera Anthony Y. Sun, M.D., our President and Chief Executive Officer, serves as Chief Executive Officer and a member of the board of directors of Zentera, and Kevin D. Bunker, Ph.D., our Chief Operating Officer, serves as a member of the board of directors of Zentera. Accordingly, the Company identifies Zentera as a related party. In May 2020, we entered into the Zentera Sublicenses, pursuant to which we collaborate with Zentera on the development and comm ercialization of ZN-c3, ZN-c5 and ZN-d5, respectively, in the Zentera Collaboration Territory. Under the terms of the Zentera Sublicenses, Zentera is responsible for the costs of developing the Collaboration Products in the Zentera Collaboration Territory, and we are responsible for the costs of developing the Collaboration Products outside the Zentera Collaboration Territory, provided that Zentera will reimburse us for a portion of its costs for global data management, pharmacovigilance, safety database management, and chemistry, manufacturing and controls activities with respect to each Collaboration Product. Prior to the deconsolidation of Zentera during the three months ended September 30, 2021, these costs were eliminated in consolidation. For the three months ended September 30, 2021, the amounts incurred under this arrangement totaled $2.9 million and are presented as contra-research and development expense in the consolidated statement of operations.

Interim Unaudited Financial S_2

Interim Unaudited Financial Statements (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of PresentationThe accompanying interim unaudited condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”) and with the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) related to a quarterly report on Form 10-Q. The year-end condensed consolidated balance sheet data was derived from the Company’s audited financial statements but does not include all disclosures required by U.S. GAAP. These condensed consolidated financial statements and notes thereto should be read in conjunction with the Company’s audited financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2020, filed with the SEC on March 25, 2021. The unaudited financial information for the interim periods presented herein reflects all adjustments which, in the opinion of management, are necessary for a fair presentation of the financial condition and results of operation for the periods presented, with such adjustments consisting only of normal recurring adjustments.
Consolidation	The condensed consolidated financial statements include our accounts and our wholly-owned subsidiaries and variable interest entity (“VIE”) for which we are the primary beneficiary. All intercompany transactions and balances have been eliminated in consolidation. We evaluate our ownership, contractual and other interests in entities that are not wholly-owned by us to determine if these entities are VIEs, and, if so, whether we are the primary beneficiary of the VIE. In determining whether we are the primary beneficiary of a VIE and therefore required to consolidate the VIE, we apply a qualitative approach that determines whether we have both (1) the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and (2) the obligation to absorb losses of, or the rights to receive benefits from, the VIE that could potentially be significant to that VIE. We continuously assess whether we are the primary beneficiary of a VIE as changes to existing relationships or future transactions may result in the consolidation or deconsolidation, as the case may be, of such VIE. The equity method is used to account for investments in which we have the ability to exercise significant influence, but not control, over the investee. Such investments are recorded on the balance sheet, and the share of net income or losses of equity investments is recognized on a one quarter lag in investment and other income (expense), net.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in our consolidated financial statements and accompanying notes. On an ongoing basis, we evaluate our estimates and judgments, which are based on historical and anticipated results and trends and on various other assumptions that management believes to be reasonable under the circumstances. By their nature, estimates are subject to an inherent degree of uncertainty and, as such, actual results may differ from management’s estimates. Though the impact of the COVID-19 pandemic to our business and operating results presents additional uncertainty, we continue to use the best information available to inform our critical accounting estimates.
Equity Method Accounting	Equity Method AccountingWe have significant influence, but not a controlling interest, in Zentera. From the deconsolidation of Zentera during July 2021 prospectively, this investment is accounted for using the equity method. Our share of earnings or losses of the investment entity are reported on the consolidated statement of operations through investment and other income, net, with a corresponding increase or decrease to the equity investment carried on the statement of financial position. This information is generally not received sufficiently timely for us to record our portion of earnings or loss in the current financial statements and therefore we report our portion of earnings or loss on a one quarter lag.
Adoption and Pending Adoption of Recent Accounting Pronouncements	Adoption and Pending Adoption of Recent Accounting Pronouncements The following table provides a brief description of recently issued accounting standards, those adopted in the current period and those not yet adopted: Standard Description Effective Date Effect on the Financial In January 2020, the FASB issued ASU 2020-01, Investments – Equity Securities (Topic 321) This standard clarifies the interaction between accounting standards related to equity securities (ASC 321), equity method investments (ASC 323), and certain derivatives (ASC 815). January 1, 2021 As of January 1, 2021, we did not hold equity securities, equity method investments or derivatives. The impact of this new accounting guidance in 2021 did not have a material impact to our consolidated financial statements at the time of adoption. As of July 2021, we hold an equity method investment which is accounted for under ASC 323. The investment is recorded on the consolidated statement of financial position at fair value as of the date of deconsolidation. The Company’s share of earnings or losses of the investment entity are reported on the consolidated statement of operations through investment and other income, net with a corresponding increase or decrease to the equity investment.

Interim Unaudited Financial S_3

Interim Unaudited Financial Statements (Tables)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Recently Issued Accounting Standards Adopted and Not Yet Adopted	The following table provides a brief description of recently issued accounting standards, those adopted in the current period and those not yet adopted: Standard Description Effective Date Effect on the Financial In January 2020, the FASB issued ASU 2020-01, Investments – Equity Securities (Topic 321) This standard clarifies the interaction between accounting standards related to equity securities (ASC 321), equity method investments (ASC 323), and certain derivatives (ASC 815). January 1, 2021 As of January 1, 2021, we did not hold equity securities, equity method investments or derivatives. The impact of this new accounting guidance in 2021 did not have a material impact to our consolidated financial statements at the time of adoption. As of July 2021, we hold an equity method investment which is accounted for under ASC 323. The investment is recorded on the consolidated statement of financial position at fair value as of the date of deconsolidation. The Company’s share of earnings or losses of the investment entity are reported on the consolidated statement of operations through investment and other income, net with a corresponding increase or decrease to the equity investment.

Business Combinations (Tables)

Business Combinations (Tables)	9 Months Ended
	Sep. 30, 2021
Business Combination and Asset Acquisition [Abstract]
Schedule of Assets and Liabilities of VIE	Total assets and liabilities of Kalyra as of September 30, 2021 and December 31, 2020 are as follows (in thousands): September 30, December 31, 2021 2020 Cash and cash equivalents $ 556 $ 417 Other current assets 107 82 In-process research and development — 8,800 Goodwill 3,736 3,736 Accounts payable and accrued expenses 124 83 Deferred tax liability — 2,463 Noncontrolling interests $ 564 $ 6,705
Reconciliation of Equity Attributable to Noncontrolling Interest	The following is a reconciliation of equity (net assets) attributable to the noncontrolling interest (in thousands): September 30, 2021 Noncontrolling interest at beginning of period $ 6,705 Net loss attributable to noncontrolling interest (6,141) Noncontrolling interest at end of period $ 564

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Components of Available-for-sale Marketable Securities	Available-for-sale marketable securities consisted of the following (in thousands): September 30, 2021 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper 239,391 23 (2) 239,412 Corporate Debt Securities 10,145 — (3) 10,142 US Government Agencies 35,731 6 — 35,737 US Treasury 40,685 9 (1) 40,693 325,952 38 (6) 325,984 December 31, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper 147,382 14 (8) 147,388 Corporate Debt Securities 23,576 1 (6) 23,571 US Government Agencies 81,455 32 (1) 81,486 US Treasury 31,105 4 — 31,109 283,518 51 (15) 283,554
Contractual Maturities of Available-for-sale Debt Securities	Contractual maturities of available-for-sale debt securities are as follows (in thousands): September 30, 2021 December 31, 2020 Estimated Fair Value Due within one year $ 315,988 $ 247,455 After one but within five years 9,996 36,099 $ 325,984 $ 283,554
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following table summarizes, by major security type, our cash equivalents and available-for-sale marketable securities that are measured at fair value on a recurring basis and are categorized using the fair value hierarchy (in thousands): September 30, 2021 December 31, 2020 Level 1 Level 2 Total estimated fair value Level 1 Level 2 Total estimated fair value Cash equivalents: Money market funds 25,648 — 25,648 $ 24,016 $ — $ 24,016 Corporate Debt Securities — — — — 4,999 4,999 Total cash equivalents: 25,648 — 25,648 24,016 4,999 29,015 Available-for-sale marketable securities: Commercial paper — 239,412 239,412 — 147,388 147,388 Corporate Debt Securities — 10,142 10,142 — 23,571 23,571 US Government Agencies — 35,737 35,737 — 81,486 81,486 US Treasury securities 40,693 — 40,693 31,109 — 31,109 Total available-for-sale marketable securities: 40,693 285,291 325,984 31,109 252,445 283,554 Total assets measured at fair value 66,341 285,291 351,632 $ 55,125 $ 257,444 $ 312,569

Prepaid Expenses and Other As_2

Prepaid Expenses and Other Assets (Tables)	9 Months Ended
	Sep. 30, 2021
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Summary of Prepaid Expenses and Other Assets	Prepaid expenses and other assets consisted of the following (in thousands): September 30, December 31, 2021 2020 Prepaid insurance $ 1,661 $ 1,021 Prepaid software licenses and maintenance 207 563 Foreign R&D credit refund 1,345 692 Prepaid research and development expenses 9,136 5,963 Interest receivable 288 478 Zentera receivable 2,940 — Other prepaid expenses 888 441 Total prepaid expenses and other assets 16,465 9,158 Less long-term portion 6,042 2,976 Total prepaid expenses and other assets, current $ 10,423 $ 6,182

Property and Equipment, net (Ta

Property and Equipment, net (Tables)	9 Months Ended
	Sep. 30, 2021
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment, net	Property and equipment, net consisted of the following (in thousands): September 30, December 31, 2021 2020 Computer and Office Equipment $ 563 $ 529 Lab Equipment 1,883 424 Leasehold Improvements 49 49 Construction in Progress 2,787 347 Subtotal 5,282 1,349 Accumulated depreciation and amortization (584) (250) Property and equipment, net $ 4,698 $ 1,099

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2021
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consist of the following (in thousands): September 30, December 31, 2021 2020 Accrued research and development expenses $ 19,589 $ 11,947 Accrued employee expenses 7,883 5,649 Accrued general and administrative expenses 2,268 996 Lease liability 862 902 Taxes payable 767 410 Other $ — $ 36 Total accrued expenses $ 31,369 $ 19,940

Members_ Equity (Tables)

Members’ Equity (Tables)	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Schedule of Share-based Compensation Expense	Total share-based compensation expense related to share based awards was comprised of the following (in thousands): Three Months Ended Nine Months Ended 2021 2020 2021 2020 Research and development expense $ 3,697 $ 2,180 $ 10,746 $ 4,606 General and administrative expense 3,959 5,069 16,520 10,653 Total share-based compensation expense $ 7,656 $ 7,249 $ 27,266 $ 15,259 Share-based compensation expense by type of share-based award (in thousands): Three Months Ended Nine Months Ended 2021 2020 2021 2020 Profit Interest Award Units $ — $ — $ — $ 329 Stock Options 5,596 2,212 14,267 3,814 Employee Stock Purchase Plan 103 — 213 — RSAs and RSUs 1,957 5,037 12,786 11,116 $ 7,656 $ 7,249 $ 27,266 $ 15,259
Schedule of Valuation Assumptions	The fair value of the profits interest awards is estimated using an option pricing model with the following assumptions: Nine Months Ended 2020 Members’ equity value (in thousands) $ 271,207 Threshold amounts (in thousands) $ 309,824 Risk free interest rate 1.5 % Volatility 75.0 % Time to liquidity (in years) 1.1 Lack of marketability discount 26.5 % Grant date fair value $ 3.06 September 30, 2021 September 30, 2020 Expected volatility 73.9% - 76.6% 76.6% - 78.2% Average expected term (in years) 5.2 - 6.2 5.7 - 6.0 Risk-free interest rate 0.5% - 1.1% 0.4% - 0.5% Expected dividend yield — % — %
Schedule of Valuation Assumptions, ESPP	The weighted average assumptions used to estimate the fair value of stock purchase rights under the employee stock purchase plan (“ESPP”) are as follows: Ended September 30, 2021 2020 ESPP Volatility 64 % — Expected term (years) 0.5 — Risk free rate — % — Expected dividend yield — —
Share-based Compensation Expense by Type of Share-based Award	Total unrecognized estimated compensation cost by type of award and the weighted average requisite service period over which such expense is expected to be recognized (in thousands, unless otherwise noted): September 30, 2021 Unrecognized Remaining Stock options $ 65,008 3.05 RSAs $ 1,472 1.84 RSUs $ 7,793 2.29 ESPP $ — 0

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Operating Lease Payments	Approximate annual future minimum operating lease payments as of September 30, 2021 are as follows (in thousands): Year Operating Leases 2021 $ 271 2022 637 Total minimum lease payments: 908 Less: imputed interest (46) Total operating lease liabilities 862

Net Loss Per Common Share_Cla_2

Net Loss Per Common Share/Class A Common Unit (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Loss Per Unit	Basic and diluted net loss per common share/Class A common unit were calculated as follows (in thousands except per share and per unit amounts): Three Months Ended Nine Months Ended 2021 2020 2021 2020 Numerator: Net loss attributable to Zentalis $ (4,191) $ (34,555) $ (108,666) $ (77,538) Denominator: Weighted average number of common shares outstanding, basic and diluted 44,609 37,959 41,918 24,143 Net loss per common share $ (0.09) $ (0.91) $ (2.59) $ (3.21)
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Unit	The following common stock equivalents have been excluded from the calculations of diluted net loss per common share because their inclusion would be antidilutive (in thousands). September 30, 2021 2020 Outstanding stock options 4,055 2,783 Unvested RSAs 447 845 Unvested RSUs 364 1,102 4,866 4,730

Organization and Business (Deta

Organization and Business (Details) $ / shares in Units, $ in Thousands	Jul. 01, 2021shares	Aug. 03, 2020shares	Apr. 07, 2020USD ($)$ / sharesshares	Apr. 02, 2020$ / sharesshares	Dec. 21, 2017	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)
Class of Stock [Line Items]
Exchange ratio					1
Proceeds from issuance of common stock in initial public offering, net | $			$ 190,000			$ 0	$ 172,482
Issuance fees and expenses | $			17,600
IPO
Class of Stock [Line Items]
Share price (in dollars per sharee) | $ / shares				$ 18
Proceeds from issuance of common stock in initial public offering, net | $			190,000
Issuance fees and expenses | $			$ 17,600
Common Stock | IPO
Class of Stock [Line Items]
Share price (in dollars per sharee) | $ / shares			$ 18
Number of shares converted (in shares) | shares				25,288,854
Number of shares issued and sold (in shares) | shares			10,557,000
Common Stock | Underwriters
Class of Stock [Line Items]
Share price (in dollars per sharee) | $ / shares			$ 18
Number of shares issued and sold (in shares) | shares	465,000	618,750	1,377,000
RSAs | IPO
Class of Stock [Line Items]
Number of shares converted (in shares) | shares				1,160,277

Significant Transactions (Detai

Significant Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Investment in Zentera Therapeutics	$ 39,326		$ 39,326		$ 0
Gain on deconsolidation of Zentera, net of tax	51,582	$ 0	51,582	$ 0
Zentera
Schedule of Equity Method Investments [Line Items]
Deferred tax liability, deconsolidation of Zentera	1,700		$ 1,700
Gain on deconsolidation of Zentera, net of tax	51,600
Contra-research and development expense	$ 2,900

Business Combinations - Narrati

Business Combinations - Narrative (Details) - USD ($)	Dec. 21, 2017	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
IPR&D impairment			$ 8,800,000	$ 0
In-process research and development		$ 0	0			$ 8,800,000
Reversal of deferred tax liability due to IPR&D impairment		2,400,000	2,400,000
In Process Research and Development
Variable Interest Entity [Line Items]
IPR&D impairment		8,800,000
In-process research and development		0	0		$ 8,800,000
VIE, Primary Beneficiary
Variable Interest Entity [Line Items]
In-process research and development		$ 0	$ 0			$ 8,800,000
Kalyra Pharmaceuticals, Inc.
Variable Interest Entity [Line Items]
Cash payments to acquire interest	$ 4,500,000
Ownership percentage	25.00%

Business Combinations - Assets

Business Combinations - Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 40,807	$ 54,951	$ 92,552
In-process research and development	0	8,800
Goodwill	3,736	3,736
Deferred tax liability	1,670	2,480
Noncontrolling interests	564	24,795
VIE, Primary Beneficiary
Variable Interest Entity [Line Items]
Cash and cash equivalents	556	417
Other current assets	107	82
In-process research and development	0	8,800
Goodwill	3,736	3,736
Accounts payable and accrued expenses	124	83
Deferred tax liability	0	2,463
Noncontrolling interests	$ 564	$ 6,705

Business Combinations - Rollfor

Business Combinations - Rollforward of Noncontrolling Interest (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Noncontrolling interest at beginning of period			$ 24,795
Net loss attributable to noncontrolling interest	$ 6,301	$ 110	7,332	$ 654
Noncontrolling interest at end of period	564		564
VIE, Primary Beneficiary
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Noncontrolling interest at beginning of period			6,705
Net loss attributable to noncontrolling interest			(6,141)
Noncontrolling interest at end of period	$ 564		$ 564

Fair Value Measurement - Compon

Fair Value Measurement - Components of Available-for-sale Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 325,952	$ 283,518
Gross Unrealized Gains	38	51
Gross Unrealized Losses	(6)	(15)
Debt securities, available-for-sale, fair value	325,984	283,554
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	239,391	147,382
Gross Unrealized Gains	23	14
Gross Unrealized Losses	(2)	(8)
Debt securities, available-for-sale, fair value	239,412	147,388
Corporate Debt Securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	10,145	23,576
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(3)	(6)
Debt securities, available-for-sale, fair value	10,142	23,571
US Government Agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	35,731	81,455
Gross Unrealized Gains	6	32
Gross Unrealized Losses	0	(1)
Debt securities, available-for-sale, fair value	35,737	81,486
US Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	40,685	31,105
Gross Unrealized Gains	9	4
Gross Unrealized Losses	(1)	0
Debt securities, available-for-sale, fair value	$ 40,693	$ 31,109

Fair Value Measurement - Contra

Fair Value Measurement - Contractual Maturities of Available-for-sale Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Due within one year	$ 315,988	$ 247,455
After one but within five years	9,996	36,099
Total	$ 325,984	$ 283,554

Fair Value Measurement - Fair V

Fair Value Measurement - Fair Value of Assets Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	$ 25,648	$ 29,015
Marketable securities, available-for-sale	325,984	283,554
Total fair value of assets	351,632	312,569
Fair Value, Inputs, Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	25,648	24,016
Marketable securities, available-for-sale	40,693	31,109
Total fair value of assets	66,341	55,125
Fair Value, Inputs, Level 2
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	0	4,999
Marketable securities, available-for-sale	285,291	252,445
Total fair value of assets	285,291	257,444
Commercial paper
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable securities, available-for-sale	239,412	147,388
Commercial paper | Fair Value, Inputs, Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable securities, available-for-sale	0	0
Commercial paper | Fair Value, Inputs, Level 2
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable securities, available-for-sale	239,412	147,388
Corporate Debt Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable securities, available-for-sale	10,142	23,571
Corporate Debt Securities | Fair Value, Inputs, Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable securities, available-for-sale	0	0
Corporate Debt Securities | Fair Value, Inputs, Level 2
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable securities, available-for-sale	10,142	23,571
US Government Agencies
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable securities, available-for-sale	35,737	81,486
US Government Agencies | Fair Value, Inputs, Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable securities, available-for-sale	0	0
US Government Agencies | Fair Value, Inputs, Level 2
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable securities, available-for-sale	35,737	81,486
US Treasury securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable securities, available-for-sale	40,693	31,109
US Treasury securities | Fair Value, Inputs, Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable securities, available-for-sale	40,693	31,109
US Treasury securities | Fair Value, Inputs, Level 2
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable securities, available-for-sale	0	0
Money market funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	25,648	24,016
Money market funds | Fair Value, Inputs, Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	25,648	24,016
Money market funds | Fair Value, Inputs, Level 2
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	0	0
Corporate Debt Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	0	4,999
Corporate Debt Securities | Fair Value, Inputs, Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	0	0
Corporate Debt Securities | Fair Value, Inputs, Level 2
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	$ 0	$ 4,999

Prepaid Expenses and Other As_3

Prepaid Expenses and Other Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid insurance	$ 1,661	$ 1,021
Prepaid software licenses and maintenance	207	563
Foreign R&D credit refund	1,345	692
Prepaid research and development expenses	9,136	5,963
Interest receivable	288	478
Zentera receivable	2,940	0
Other prepaid expenses	888	441
Total prepaid expenses and other assets	16,465	9,158
Less long-term portion	6,042	2,976
Total prepaid expenses and other assets, current	$ 10,423	$ 6,182

Property and Equipment, net - S

Property and Equipment, net - Summary (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Subtotal	$ 5,282	$ 1,349
Accumulated depreciation and amortization	(584)	(250)
Property and equipment, net	4,698	1,099
Computer and Office Equipment
Property, Plant and Equipment [Line Items]
Subtotal	563	529
Lab Equipment
Property, Plant and Equipment [Line Items]
Subtotal	1,883	424
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Subtotal	49	49
Construction in Progress
Property, Plant and Equipment [Line Items]
Subtotal	$ 2,787	$ 347

Property and Equipment, net - N

Property and Equipment, net - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Property, Plant and Equipment [Abstract]
Depreciation and amortization	$ 137	$ 51	$ 335	$ 127

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Accrued research and development expenses	$ 19,589	$ 11,947
Accrued employee expenses	7,883	5,649
Accrued general and administrative expenses	2,268	996
Lease liability	862	902
Taxes payable	767	410
Other	0	36
Total accrued expenses	$ 31,369	$ 19,940

Convertible Preferred Units - N

Convertible Preferred Units - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	Apr. 07, 2020	Feb. 29, 2020	Sep. 30, 2019	Dec. 31, 2017	Sep. 30, 2015	Mar. 31, 2016	Aug. 31, 2018	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Class of Stock [Line Items]
Shares issued (in shares)								0		0
Net proceeds from issuance of convertible preferred units								$ 0	$ 14,228
Issuance costs of financing	$ 17,600
Units authorized (in shares)								0		0
Shares outstanding (in shares)								0		0
Dividends declared (in dollars per share)								$ 0
Automatic conversion feature, minimum gross cash proceeds received in a public offering								$ 75,000
Series A Preferred Units
Class of Stock [Line Items]
Convertible preferred units issued (in shares)					1,293,104
Par value per share (in dollars per share)					$ 11.60	$ 11.60
Shares issued (in shares)						286,205
Gross proceeds from issuance of convertible preferred units					$ 15,000	$ 3,300
Net proceeds from issuance of convertible preferred units					14,900
Issuance costs of financing					$ 100	$ 39
Conversion price (in dollars per share)								$ 11.60
Liquidation preference (in dollars per share)								11.60
Series B Preferred Units
Class of Stock [Line Items]
Par value per share (in dollars per share)				$ 12.43			$ 12.43
Shares issued (in shares)				2,735,320			788,419
Gross proceeds from issuance of convertible preferred units				$ 34,000			$ 9,800
Net proceeds from issuance of convertible preferred units				32,100			9,500
Issuance costs of financing				$ 1,900			$ 300
Conversion price (in dollars per share)								12.43
Liquidation preference (in dollars per share)								12.43
Series C Preferred Units
Class of Stock [Line Items]
Par value per share (in dollars per share)		$ 17.50	$ 17.50
Shares issued (in shares)		867,194	4,847,106
Gross proceeds from issuance of convertible preferred units		$ 15,200	$ 84,800
Net proceeds from issuance of convertible preferred units		14,200	81,900
Issuance costs of financing		$ 1,000	$ 2,900
Conversion price (in dollars per share)								17.50
Liquidation preference (in dollars per share)								$ 17.50

Members_ Equity - Narrative (De

Members’ Equity - Narrative (Details) - USD ($)	Jul. 01, 2021	Aug. 03, 2020	Apr. 07, 2020	Apr. 02, 2020	Apr. 30, 2020	Dec. 31, 2017	Sep. 30, 2015	Mar. 31, 2016	Aug. 31, 2018	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Sep. 30, 2019	Dec. 21, 2017
Class of Stock [Line Items]
Common stock issued (in shares)						5,187,554				45,198,528		41,040,286
Common stock outstanding (in shares)						5,187,554				45,198,528		41,040,286
Common stock subject to future vesting provisions (in shares)						406,831
Common stock, shares authorized (in shares)				250,000,000						250,000,000		250,000,000
Common stock, par value (in dollars per share)				$ 0.001						$ 0.001		$ 0.001
Preferred stock, shares authorized (in shares)				10,000,000						10,000,000		10,000,000
Preferred stock, par value (in dollars per share)				$ 0.001						$ 0.001		$ 0.001
Proceeds from issuance of common stock in initial public offering, net			$ 190,000,000							$ 0	$ 172,482,000
Issuance fees and expenses			17,600,000
Proceeds from issuance of common stock, net										$ 162,223,000	155,899,000
Issuance of common stock upon exercise of options, net (in shares)										100,000
Shares issued upon vesting of certain RSAs (in shares)										300,000
Stock Options
Class of Stock [Line Items]
Generally expected vesting term of the option contract (in years)										10 years
Options outstanding (in shares)										4,100,000
RSAs
Class of Stock [Line Items]
Non-Option equity instruments, outstanding (in shares)										400,000
RSUs
Class of Stock [Line Items]
Non-Option equity instruments, outstanding (in shares)										400,000
Employee Stock Purchase Plan
Class of Stock [Line Items]
ESPP maximum percent of compensation to contribute										20.00%
Maximum contribution amount										$ 21,250
ESPP purchase price of common stock, percent of market price										85.00%
Offering period										6 months
Zentera Stock Plan
Class of Stock [Line Items]
Employee benefits and share-based compensation										$ 138,000	$ 187,000
IPO
Class of Stock [Line Items]
Share price (in dollars per sharee)				$ 18
Proceeds from issuance of common stock in initial public offering, net			190,000,000
Issuance fees and expenses			$ 17,600,000
Follow-On Offering
Class of Stock [Line Items]
Gross proceeds from issuance of common stock		$ 166,000,000
Expenses and fees from the issuance of common stock		$ 10,800,000
Class A Common Units
Class of Stock [Line Items]
Issuance of common stock in connection with an offering, net of underwriting discounts, commissions and offering costs (in shares)										0	0
Common units subject to future vesting conditions (in shares)										0	0
Common units, authorized (in shares)						15,000,000							20,000,000
Class B Common Units
Class of Stock [Line Items]
Issuance of common stock in connection with an offering, net of underwriting discounts, commissions and offering costs (in shares)										0	70,000
Common units, authorized (in shares)						872,620							3,458,522
Stock issued upon conversion of units (in shares)						703,000
Class B Common Units | The Plan
Class of Stock [Line Items]
Shares authorized to be issued under plan (in shares)														3,458,522
Class B Common Units | The 2020 Plan | Maximum
Class of Stock [Line Items]
Shares authorized to be issued under plan (in shares)					1,250,000
Common Stock | The 2020 Plan
Class of Stock [Line Items]
Shares authorized to be issued under plan (in shares)					5,600,000
Percent of common stock outstanding used as threshold to calculate shares available for issuance					5.00%
Non-Option equity instruments, outstanding (in shares)										4,418,484
Number of shares available for future grants (in shares)										2,237,052
Common Stock | Corporate Conversion
Class of Stock [Line Items]
Issuance of common stock in connection with an offering, net of underwriting discounts, commissions and offering costs (in shares)				0
Common Stock | IPO
Class of Stock [Line Items]
Stock issued upon conversion of units (in shares)				25,288,854
Stock issued (in dollars per share)			$ 18
Number of shares issued and sold (in shares)			10,557,000
Share price (in dollars per sharee)			$ 18
Common Stock | Underwriters
Class of Stock [Line Items]
Number of shares issued and sold (in shares)	465,000	618,750	1,377,000
Share price (in dollars per sharee)			$ 18
Common Stock | Follow-On Offering
Class of Stock [Line Items]
Number of shares issued and sold (in shares)		4,743,750
Share price (in dollars per sharee)		$ 35
Common Stock | Follow-On Public Offering
Class of Stock [Line Items]
Number of shares issued and sold (in shares)	3,565,000
Share price (in dollars per sharee)	$ 48.50
Expenses and fees from the issuance of common stock	$ 10,700,000
Proceeds from issuance of common stock, net	$ 172,900,000
RSAs | IPO
Class of Stock [Line Items]
Stock issued upon conversion of units (in shares)				1,160,277
Series A Preferred Units
Class of Stock [Line Items]
Issuance fees and expenses							$ 100,000	$ 39,000
Preferred units authorized (in shares)						1,638,000
Series B Preferred Units
Class of Stock [Line Items]
Issuance fees and expenses						$ 1,900,000			$ 300,000
Preferred units authorized (in shares)						3,621,000

Members_ Equity - Share-based C

Members’ Equity - Share-based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 7,656	$ 7,249	$ 27,266	$ 15,259
Research and development expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	3,697	2,180	10,746	4,606
General and administrative expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 3,959	$ 5,069	$ 16,520	$ 10,653

Members_ Equity - Share-based_2

Members’ Equity - Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 7,656	$ 7,249	$ 27,266	$ 15,259
Profit Interest Award Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	0	0	0	329
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	5,596	2,212	14,267	3,814
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	103	0	213	0
RSAs and RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 1,957	$ 5,037	$ 12,786	$ 11,116

Members_ Equity - Fair Value As

Members’ Equity - Fair Value Assumptions for Profit Interest Awards (Details) - Profit Interest Awards $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)$ / shares
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Members’ equity value (in thousands)	$ 271,207
Threshold amounts (in thousands)	$ 309,824
Risk free rate (as a percent)	1.50%
Volatility (as a percent)	75.00%
Time to liquidity (in years)	1 year 1 month 6 days
Lack of marketability discount (as a percent)	26.50%
Grant date fair value (USD per share) | $ / shares	$ 3.06

Members_ Equity - Fair Value _2

Members’ Equity - Fair Value Assumptions for Stock Options (Details) - Stock Options	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected volatility, minimum	73.90%	76.60%
Expected volatility, maximum	76.60%	78.20%
Risk-free interest rate, minimum (as a percent)	0.005%	0.004%
Risk-free interest rate, maximum (as a percent)	0.011%	0.005%
Expected dividend yield	0.00%	0.00%
Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Average expected term (in years)	5 years 2 months 12 days	5 years 8 months 12 days
Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Average expected term (in years)	6 years 2 months 12 days	6 years

Members_ Equity - Fair Value _3

Members’ Equity - Fair Value Assumptions for ESPP (Details) - Employee Stock Purchase Plan	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Volatility (as a percent)	64.00%	0.00%
Average expected term (in years)	6 months
Risk free rate (as a percent)	0.00%	0.00%
Expected dividend yield	0.00%	0.00%

Members_ Equity - Unrecognized

Members’ Equity - Unrecognized Compensation Cost (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized expense, stock options	$ 65,008
Remaining Weighted-Average Recognition Period (years)	3 years 18 days
RSAs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized expense, other than options	$ 1,472
Remaining Weighted-Average Recognition Period (years)	1 year 10 months 2 days
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized expense, other than options	$ 7,793
Remaining Weighted-Average Recognition Period (years)	2 years 3 months 14 days
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized expense, other than options	$ 0

Commitment and Contingencies -

Commitment and Contingencies - Future Minimum Lease Payments (Details) $ in Thousands	Sep. 30, 2021USD ($)
Commitments and Contingencies Disclosure [Abstract]
2021	$ 271
2022	637
Total minimum lease payments:	908
Less: imputed interest	(46)
Total operating lease liabilities	$ 862

Commitment and Contingencies _2

Commitment and Contingencies - Narrative (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021USD ($)lease
Lessee, Lease, Description [Line Items]
Operating lease, weighted-average remaining lease term	9 months 18 days
Number of leases not yet commenced | lease	2
Total minimum lease payments on leases not yet commenced | $	$ 74.6
Minimum
Lessee, Lease, Description [Line Items]
Operating leases not yet commenced, term	10 years
Maximum
Lessee, Lease, Description [Line Items]
Operating leases not yet commenced, term	11 years

Net Loss Per Common Share_Cla_3

Net Loss Per Common Share/Class A Common Unit - Calculation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net loss attributable to Zentalis	$ (4,191)	$ (34,555)	$ (108,666)	$ (77,538)
Denominator:
Weighted average number of common shares outstanding, basic (in shares)	44,609	37,959	41,918	24,143
Weighted average number of common shares outstanding, diluted (in shares)	44,609	37,959	41,918	24,143
Net loss per common share outstanding, basic (USD per share)	$ (0.09)	$ (0.91)	$ (2.59)	$ (3.21)
Net loss per common share outstanding, diluted (USD per share)	$ (0.09)	$ (0.91)	$ (2.59)	$ (3.21)

Net Loss Per Common Share_Cla_4

Net Loss Per Common Share/Class A Common Unit - Antidilutive Securities (Details) - shares shares in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per unit (in shares)	4,866	4,730
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per unit (in shares)	4,055	2,783
RSAs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per unit (in shares)	447	845
RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per unit (in shares)	364	1,102

Related Party Disclosures (Deta

Related Party Disclosures (Details) - USD ($)	Dec. 21, 2017	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Related Party Transaction [Line Items]
Number of shares acquired (in shares)		0		0		0
Zentera
Related Party Transaction [Line Items]
Contra-research and development expense		$ 2,900,000
Affiliated Entity | License Agreement
Related Party Transaction [Line Items]
Expenses from transactions with related party				$ 10,000,000	$ 0
Affiliated Entity | Master Services Agreement
Related Party Transaction [Line Items]
Expenses from transactions with related party		0	$ 0	0	17,000,000
Due to related parties		0	0	0	0
Director | Master Services Agreement
Related Party Transaction [Line Items]
Due to related parties		$ 1,000,000	$ 0	$ 1,000,000	$ 0
VIE, Primary Beneficiary | Kalyra Pharmaceuticals, Inc.
Related Party Transaction [Line Items]
Share price (in dollars per share)	$ 0.26
Cash payments to acquire interest	$ 4,500,000
Agreement term				15 years
VIE, Primary Beneficiary | Series B Preferred Units | Kalyra Pharmaceuticals, Inc.
Related Party Transaction [Line Items]
Number of shares acquired (in shares)	17,307,692