Zentalis Pharmaceuticals (ZNTL) 10-Q 9 Nov 20 2020 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2020	Nov. 05, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
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	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		40,613,857
Entity Central Index Key	0001725160
Amendment Flag	false
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 92,552	$ 67,246
Marketable securities, available-for-sale	274,884	0
Accounts receivable from government grants, net	122	140
Prepaid expenses and other current assets	5,178	1,505
Total current assets	372,736	68,891
Property and equipment, net	471	501
Operating lease right-of-use assets	1,925	2,335
Prepaid expenses and other assets	4,245	2,134
Deferred financing costs	0	841
Goodwill	3,736	3,736
In-process research and development	8,800	8,800
Restricted cash	1,320	243
Total assets	393,233	87,481
Current liabilities
Accounts payable	5,437	4,289
Accrued expenses	18,469	10,608
Total current liabilities	23,906	14,897
Deferred tax liability	2,463	2,463
Other long-term liabilities	1,031	1,700
Total liabilities	27,400	19,060
Commitments and contingencies
Convertible preferred units; Redemption value of $146,944,000 at December 31, 2019	0	141,706
EQUITY (DEFICIT)
Preferred stock, value	0	0
Common Stock, value	41	0
Additional paid-in capital	501,522	0
Accumulated other comprehensive income	23	0
Accumulated deficit	(160,531)	(82,993)
Total stockholders’ equity/members’ (deficit)	341,055	(80,106)
Noncontrolling interests	24,778	6,821
Total equity (deficit)	365,833	(73,285)
Total liabilities, convertible preferred units and equity (deficit)	393,233	87,481
Class A Common Units
EQUITY (DEFICIT)
Class A and B common units, issuance value	0	709
Class B Common Units
EQUITY (DEFICIT)
Class A and B common units, issuance value	$ 0	$ 2,178

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Convertible preferred units, redemption value		$ 146,944,000
Preferred stock, par value (in dollars per share)	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000
Preferred stock, shares issued (in shares)	0
Preferred stock, shares outstanding (in shares)	0
Common stock, par value (in dollars per share)	$ 0.001
Common stock, shares authorized (in shares)	250,000,000
Common stock issued (in shares)	40,614,453
Common stock outstanding (in shares)	40,614,453
Class A Common Units
Common units, authorized (in shares)		20,000,000
Common units, issued (in shares)		5,601,478
Common units, outstanding (in shares)		5,601,478
Class B Common Units
Common units, authorized (in shares)		3,458,522
Common units, issued (in shares)		2,670,668
Common units, outstanding (in shares)		2,670,668

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating Expenses
Research and development	$ 24,670	$ 10,739	$ 55,380	$ 26,517
General and administrative	10,097	1,844	23,162	5,423
Total operating expenses	34,767	12,583	78,542	31,940
Operating loss	(34,767)	(12,583)	(78,542)	(31,940)
Other Income (Expense)
Investment and other income, net	120	12	368	123
Net loss before income taxes	(34,647)	(12,571)	(78,174)	(31,817)
Income tax expense	18	1	18	15
Net loss	(34,665)	(12,572)	(78,192)	(31,832)
Net loss attributable to noncontrolling interests	(110)	(228)	(654)	(675)
Net loss attributable to Zentalis	$ (34,555)	$ (12,344)	$ (77,538)	$ (31,157)
Units used in computing net loss per Class A common unit, basic and diluted (in shares)	37,959	5,601	24,143	5,601
Common Stock
Other Income (Expense)
Net loss per share outstanding, basic and diluted (USD per share)	$ (0.91)	$ 0	$ (3.21)	$ 0
Class A Common Units
Other Income (Expense)
Net loss per share outstanding, basic and diluted (USD per share)	$ 0	$ (2.20)	$ 0	$ (5.56)

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (34,665)	$ (12,572)	$ (78,192)	$ (31,832)
Other comprehensive income:
Unrealized gain on marketable securities	19	0	23	0
Total comprehensive loss	(34,646)	(12,572)	(78,169)	(31,832)
Comprehensive loss attributable to noncontrolling interests	(110)	(228)	(654)	(675)
Comprehensive loss attributable to Zentalis	$ (34,536)	$ (12,344)	$ (77,515)	$ (31,157)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating Activities:
Consolidated net loss	$ (78,192)	$ (31,832)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	127	70
Share-based compensation	15,259	405
Amortization of premiums on marketable securities, net	224	0
Changes in operating assets and liabilities:
Accounts receivable	18	867
Prepaid expenses and other assets	(5,784)	(833)
Accounts payable and accrued liabilities	9,049	5,155
Operating lease right-of-use assets and liabilities, net	(169)	216
Net cash used in operating activities	(59,468)	(25,952)
Investing activities:
Purchases of marketable securities	(304,085)	0
Proceeds from maturities of marketable securities	29,000	0
Purchases of property and equipment	(97)	(316)
Net cash used in investing activities	(275,182)	(316)
Financing Activities:
Proceeds from issuance of common stock in initial public offering, net	172,482	0
Contributions from noncontrolling interest owners, net	18,424	0
Proceeds from the issuance of Series C convertible preferred units, net	14,228	81,883
Proceeds from issuance of common stock, net	155,899	0
Net cash provided by financing activities	361,033	81,883
Net increase in cash, cash equivalents and restricted cash	26,383	55,615
Cash, cash equivalents and restricted cash at beginning of period	67,489	25,154
Cash, cash equivalents and restricted cash at end of period	93,872	80,769
Supplemental disclosure of non-cash investing and financing activities:
Right-of-use assets obtained in exchange for operating lease liabilities	0	1,412
Costs incurred in connection with equity offering included in accounts payable and accrued liabilities	594	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents
Total cash, cash equivalents and restricted cash reported in the Consolidated Statement of Cash Flows	$ 93,872	$ 80,769

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Changes in Convertible Preferred Units and Members’/Stockholders’ Equity/(Deficit) (Statement) - USD ($) $ in Thousands	Total	IPO	Convertible Preferred Units	Class A Common Units	Class B Common Units	Series C Preferred Units	Preferred StockConvertible Preferred 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 (in shares) at Dec. 31, 2018			0
Temporary equity, beginning balance at Dec. 31, 2018			$ 0
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of Series C convertible preferred units at $17.50 per unit net of issuance costs, in shares			4,847,000
Issuance of Series C convertible preferred units at $17.50 per unit net of issuance costs	$ 0		$ 81,883
Reclassification of convertible preferred units for contingent liquidation features not within the Company's control (in shares)			5,103,000
Reclassification of convertible preferred units for contingent liquidation features not within the Company's control			$ 59,830
Temporary equity ending balance (in shares) at Sep. 30, 2019			9,950,000
Temporary equity, ending balance at Sep. 30, 2019			$ 141,713
Beginning balance, in shares at Dec. 31, 2018							5,103,000
Beginning balance at Dec. 31, 2018	32,306						$ 59,830								$ (37,330)	$ 7,536
Common units, beginning balance (in shares) at Dec. 31, 2018										5,594,000	1,612,000
Common units, beginning balance at Dec. 31, 2018										$ 672	$ 1,598
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued (in shares)					91,000						335,000
Share-based compensation expense	405									$ 6	$ 399
Reclassification of Stock to Temporary Equity, Shares							(5,103,000)
Reclassification of convertible preferred units for contingent liquidation features not within the Company's control	(59,830)						$ (59,830)
Net loss attributable to noncontrolling interests	(675)															(675)
Net loss attributable to Zentalis	(31,157)														(31,157)
Ending balance, in shares at Sep. 30, 2019							0
Ending balance at Sep. 30, 2019	$ (58,951)						$ 0								(68,487)	6,861
Common units, ending balance (in shares) at Sep. 30, 2019										5,594,000	1,947,000
Common units, ending balance at Sep. 30, 2019										$ 678	$ 1,997
Temporary equity beginning balance (in shares) at Dec. 31, 2018			0
Temporary equity, beginning balance at Dec. 31, 2018			$ 0
Temporary equity ending balance (in shares) at Dec. 31, 2019	9,950,154		9,950,000			4,847,106
Temporary equity, ending balance at Dec. 31, 2019	$ 141,706		$ 141,706			$ 81,876
Beginning balance, in shares at Dec. 31, 2018							5,103,000
Beginning balance at Dec. 31, 2018	32,306						$ 59,830								(37,330)	7,536
Common units, beginning balance (in shares) at Dec. 31, 2018										5,594,000	1,612,000
Common units, beginning balance at Dec. 31, 2018										$ 672	$ 1,598
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued (in shares)				7,093
Ending balance, in shares at Dec. 31, 2019								0
Ending balance at Dec. 31, 2019	(73,285)							$ 0				$ 0		$ 0	(82,993)	6,821
Common units, ending balance (in shares) at Dec. 31, 2019				5,601,478	2,670,668					5,601,000	2,671,000
Common units, ending balance at Dec. 31, 2019				$ 709	$ 2,178					$ 709	$ 2,178
Temporary equity beginning balance (in shares) at Jun. 30, 2019			0
Temporary equity, beginning balance at Jun. 30, 2019			$ 0
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of Series C convertible preferred units at $17.50 per unit net of issuance costs, in shares			4,847,000
Issuance of Series C convertible preferred units at $17.50 per unit net of issuance costs	0		$ 81,883
Reclassification of convertible preferred units for contingent liquidation features not within the Company's control (in shares)			5,103,000
Reclassification of convertible preferred units for contingent liquidation features not within the Company's control			$ 59,830
Temporary equity ending balance (in shares) at Sep. 30, 2019			9,950,000
Temporary equity, ending balance at Sep. 30, 2019			$ 141,713
Beginning balance, in shares at Jun. 30, 2019							5,103,000
Beginning balance at Jun. 30, 2019	13,296						$ 59,830								(56,143)	7,089
Common units, beginning balance (in shares) at Jun. 30, 2019										5,594,000	1,669,000
Common units, beginning balance at Jun. 30, 2019										$ 676	$ 1,844
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued (in shares)				0							278,000
Share-based compensation expense	155									$ 2	$ 153
Reclassification of Stock to Temporary Equity, Shares							(5,103,000)
Reclassification of convertible preferred units for contingent liquidation features not within the Company's control	(59,830)						$ (59,830)
Net loss attributable to noncontrolling interests	(228)															(228)
Net loss attributable to Zentalis	(12,344)														(12,344)
Ending balance, in shares at Sep. 30, 2019							0
Ending balance at Sep. 30, 2019	$ (58,951)						$ 0								(68,487)	6,861
Common units, ending balance (in shares) at Sep. 30, 2019										5,594,000	1,947,000
Common units, ending balance at Sep. 30, 2019										$ 678	$ 1,997
Temporary equity beginning balance (in shares) at Dec. 31, 2019	9,950,154		9,950,000			4,847,106
Temporary equity, beginning balance at Dec. 31, 2019	$ 141,706		$ 141,706			$ 81,876
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of Series C convertible preferred units at $17.50 per unit net of issuance costs, in shares	867,000
Issuance of Series C convertible preferred units at $17.50 per unit net of issuance costs	$ 14,228
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
Temporary equity ending balance (in shares) at Sep. 30, 2020			0
Temporary equity, ending balance at Sep. 30, 2020	0		$ 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				5,601,478	2,670,668					5,601,000	2,671,000
Common units, beginning balance at Dec. 31, 2019				$ 709	$ 2,178					$ 709	$ 2,178
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Cancelled During Period, Shares											(64,000)
Stock issued (in shares)					70,000			4,744,000	10,589,000
Stock issued, value	155,305	$ 172,365						$ 5	$ 11			155,300	$ 172,354
Contributions from noncontrolling interest owners	18,424															18,424
Share-based compensation expense	15,259										$ 329	14,930
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								$ (10)		$ (709)	$ (2,507)	(3,206)
Cancellation of restricted stock awards								(7,000)
Other comprehensive income	23													23
Net loss attributable to noncontrolling interests	(654)											(187)				(467)
Net loss attributable to Zentalis	(77,538)														(77,538)
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
Common units, ending balance (in shares) at Sep. 30, 2020										0	0
Common units, ending balance at Sep. 30, 2020				$ 0	$ 0					$ 0	$ 0
Temporary equity ending balance (in shares) at Sep. 30, 2020			0
Temporary equity, ending balance at Sep. 30, 2020	0		$ 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]
Stock issued (in shares)				0				4,744,000
Stock issued, value	155,305							$ 5				155,300
Share-based compensation expense	7,249											7,249
Cancellation of restricted stock awards								(7,000)
Other comprehensive income	19													19
Net loss attributable to noncontrolling interests	(110)											(187)				77
Net loss attributable to Zentalis	(34,555)														(34,555)
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
Common units, ending balance (in shares) at Sep. 30, 2020										0	0
Common units, ending balance at Sep. 30, 2020				$ 0	$ 0					$ 0	$ 0

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Changes in Convertible Preferred Units and Members’/Stockholders’ Equity/(Deficit) (Parenthetical)) - $ / shares	Sep. 30, 2020	Feb. 29, 2020	Sep. 30, 2019
Series C Preferred Units
Par value per share (in dollars per share)	$ 17.50	$ 17.50	$ 17.50

Organization and Business

Organization and Business	9 Months Ended
	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Business	Organization and Business Organization Zentalis Pharmaceuticals, Inc. (successor to Zentalis Pharmaceuticals, LLC) (“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. To date, all of the Company’s revenue has been generated in the United States. 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 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. On May 19, 2020, the Company announced the closing of a Series A financing of Zentera Therapeutics, Ltd. (“Zentera”), a majority owned biopharmaceutical company with headquarters in Shanghai, China. Contributions from noncontrolling interest members totaled $20.0 million before issuing costs of $1.6 million. The Company holds 60.2% equity interest in Zentera for purposes of the development and commercialization of ZN-c5, ZN-d5 and ZN-c3 for the treatment or preventions of disease, other than for pain, in the People’s Republic of China, Macau, Hong Kong and Taiwan. Two of our executives entered into restricted stock purchase agreements with Zentera. The associated shares vest over four years. 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. Liquidity

Interim Unaudited Financial Sta

Interim Unaudited Financial Statements	9 Months Ended
	Sep. 30, 2020
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 should be read in conjunction with the Company’s audited financial statements for the year ended December 31, 2019 included in the Company’s final prospectus for its IPO, filed pursuant to Rule 424(b) under the Securities Exchange Act of 1933, as amended, with the SEC on April 6, 2020. 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 the accounts of our wholly owned subsidiaries, majority-owned or controlled companies, and variable interest entity (“VIE”), Kalyra Pharmaceuticals, Inc. (“Kalyra”), for which we are the primary beneficiary. All intercompany transactions and balances have been eliminated in consolidation. Noncontrolling Interest The shares third parties own in Kalyra and Zentera represent an interest in their respective equity we do not control. We reflect the noncontrolling interest attributable to other owners in a separate line in our condensed consolidated statement of operations and a separate line within stockholders’ equity in our condensed consolidated balance sheet. In addition, we record a noncontrolling interest adjustment to account for equity based compensation in Zentera. This adjustment is a reclassification within stockholders’ equity from additional paid-in capital to noncontrolling interest equal to the amount of equity based compensation expense Zentera had recognized. 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. Marketable Securities Marketable securities are investments with original maturities of more than ninety days from the date of purchase that we have the ability to liquidate to fund current operations. Accordingly, those investments with contractual maturities greater than one year from the date of purchase are classified as short-term investments on the accompanying condensed consolidated balance sheets Marketable securities are considered available-for-sale and are carried at fair value with unrealized gains and losses recorded in other comprehensive income (loss) and included as a separate component of stockholders’ deficit. The cost of marketable securities is adjusted for amortization of premiums or accretion of discounts to maturity, and such amortization or accretion is included in investment and other income, net in the interim unaudited condensed consolidated statements of operations. We assess whether our available-for-sale debt securities in an unrealized loss position have credit-related losses and record such losses, and any subsequent improvements as interest income, through an allowance account. We use the specific identification method for calculating realized gains and losses on marketable securities sold. Realized gains and losses on marketable securities, if any, are included in investment and other income, net in the interim unaudited condensed consolidated statements of operations. 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 March 2020, the FASB issued ASU 2020-03, Codification Improvements to Financial Instruments This guidance makes improvements to financial instruments guidance, including the current expected credit losses guidance. January 1, 2020 We have adopted the new guidance as of January 1, 2020. The impact of the adoption was not material to the consolidated financial statements. 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 We currently do not hold equity securities, have equity method investments or derivatives. We do not believe the adoption will have a material impact on our consolidated financial position or results of operations. In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments. In November 2018 and April and May of 2019, the FASB issued additional guidance related to Topic 326. The standard amends the impairment model by requiring entities to use a forward-looking approach based on expected losses to estimate credit losses for most financial assets and certain other instruments that aren’t measured at fair value through net income. January 1, 2020 We have adopted the new guidance on January 1, 2020. The impact of the adoption was not material to the consolidated financial statements. In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes. The new guidance is intended to simplify aspects of the accounting for income taxes, including the elimination of certain exceptions to the guidance in ASC 740 related to the approach for intraperiod tax allocation, among other changes. January 1, 2020 We have adopted the new guidance on January 1, 2020. The impact of the adoption was not material to the consolidated financial statements.

Business Combinations

Business Combinations	9 Months Ended
	Sep. 30, 2020
Business Combinations [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, Zentalis 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. Total assets and liabilities of Kalyra as of September 30, 2020 and December 31, 2019 are as follows (in thousands): September 30, December 31, 2020 2019 Cash and cash equivalents $ 417 $ 712 Other current assets 31 21 In-process research and development 8,800 8,800 Goodwill 3,736 3,736 Other long-term assets 14 14 Accounts payable and accrued expenses 87 391 Deferred tax liability 2,463 2,463 Noncontrolling interests $ 6,635 $ 6,821 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 consolidated balance sheets. The following is a reconciliation of equity (net assets) attributable to the noncontrolling interest (in thousands): September 30, 2020 Noncontrolling interest at beginning of period $ 6,821 Net loss attributable to noncontrolling interest (186) Noncontrolling interest at end of period $ 6,635

Fair Value Measurement

Fair Value Measurement	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurement	Fair Value MeasurementAvailable-for-sale marketable securities consisted of the following (in thousands): September 30, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper $ 125,748 $ 9 $ (7) $ 125,750 Corporate debt securities 31,840 5 (3) 31,842 US government agencies 77,523 22 (5) 77,540 US Treasury securities 39,750 3 (1) 39,752 $ 274,861 $ 39 $ (16) $ 274,884 As of September 30, 2020, 19 o f our available-for-sale debt securities with a fair market value of $85.3 million were in a gross unrealized loss position of sixteen thousand . When evaluating an investment for impairment, we review 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, 2020, 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, 2020 Estimated Fair Value Due within one year $ 239,291 After one but within five years 35,593 $ 274,884 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, 2020 December 31, 2019 Level 1 Level 2 Total estimated fair value Level 1 Level 2 Total estimated fair value Cash equivalents: Money market funds $ 29,924 $ — $ 29,924 $ 62,961 $ — $ 62,961 US government agencies — 2,631 2,631 — — — US Treasury securities 9,999 — 9,999 — — — Corporate debt securities — 14,999 14,999 — — — Total cash equivalents: 39,923 17,630 57,553 62,961 — 62,961 Available-for-sale marketable securities: Commercial paper — 125,750 125,750 — — — Corporate debt securities — 31,842 31,842 — — — US government agencies — 77,540 77,540 — — — US Treasury securities 39,752 — 39,752 — — — Total available-for-sale marketable securities: 39,752 235,132 274,884 — — — Total assets measured at fair value $ 79,675 $ 252,762 $ 332,437 $ 62,961 $ — $ 62,961 There were no transfers between Level 1 and Level 2 of the fair value hierarchy during the nine months ended September 30, 2020. We had no instruments that were classified within Level 3 as of September 30, 2020 or December 31, 2019.

Prepaid Expenses and Other Asse

Prepaid Expenses and Other Assets	9 Months Ended
	Sep. 30, 2020
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, 2020 2019 Prepaid insurance $ 1,761 $ 150 Prepaid software licenses and maintenance 320 238 Prepaid research and development expenses 5,735 2,985 Interest receivable 511 — Upfront lease payment 810 — Other prepaid expenses 286 266 Total prepaid expenses and other current assets 9,423 3,639 Less long-term portion 4,245 2,134 Total prepaid expenses and other assets, current $ 5,178 $ 1,505

Property and Equipment, net

Property and Equipment, net	9 Months Ended
	Sep. 30, 2020
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, 2020 2019 Computer and office equipment $ 291 $ 243 Lab equipment 360 401 Leasehold improvements 43 24 Construction in progress 6 — Subtotal 700 668 Accumulated depreciation and amortization (229) (167) Property and equipment, net $ 471 $ 501 Depreciation and amortization expense for the three months ended September 30, 2020 and 2019 was approximately fifty-one thousand and twenty-five thousand, respectively. Depreciation and amortization expense for the nine months ended September 30, 2020

Accrued Expenses

Accrued Expenses	9 Months Ended
	Sep. 30, 2020
Payables and Accruals [Abstract]
Accrued Expenses	Accrued Expenses Accrued expenses consist of the following (in thousands): September 30, December 31, 2020 2019 Accrued research and development expenses $ 10,618 $ 5,465 Accrued employee expenses 4,390 2,977 Accrued general and administrative expenses 2,571 1,356 Lease liability 871 781 Other 19 29 Total accrued expenses $ 18,469 $ 10,608

Convertible Preferred Units

Convertible Preferred Units	9 Months Ended
	Sep. 30, 2020
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 Preferred Unit Issuance 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, and outstanding shares of convertible preferred units at September 30, 2020. As of December 31, 2019, the authorized, issued, and outstanding units of convertible preferred units were as follows (in thousands, except unit amounts): December 31, 2019 Series Units Units Issued Liquidation Carrying Series A convertible preferred units 1,579,309 1,579,309 $ 18,320 $ 18,226 Series B convertible preferred units 3,523,739 3,523,739 43,800 41,604 Series C convertible preferred units 5,714,300 4,847,106 84,824 81,876 Total 10,817,348 9,950,154 $ 146,944 $ 141,706 During 2019, 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, 2019 and prior to the conversion of convertible preferred units into common stock in conjunction with our IPO on April 2, 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 prior to the conversion of convertible preferred units into common stock in conjunction with our IPO on April 2, 2020. 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 units 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 into common stock. Anti-dilution protection The holders of the convertible preferred unit 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 and December 31, 2019, 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 were 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.

Equity and Share-based Compensa

Equity and Share-based Compensation	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
Equity and Share-based Compensation	Equity and Share-based Compensation 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 profit 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. During the three months ended September 30, 2020 and 2019, we did not issue any Class A common units. As of September 30, 2020 and 2019, zero and 9,572 Class A common units were subject to future vesting conditions, respectively. During the year ended December 31, 2019, 7,093 Class A common units were issued and 9,572 Class A common units were subject to future vesting conditions. In September 2019, the number of authorized Class A common units was increased to 20,000,000. 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 Offering 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. Share-based Compensation In the Company’s 2017 Profit 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, subject to restrictions as described in the Plan. The Plan was terminated in April 2020. In April 2020, 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. The number of common shares initially 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. During the nine months ended September 30, 2020, the Company granted 70,000 Class B common units to employees and directors under the Plan. The weighted average fair value of incentive units granted in the nine months ended September 30, 2020 was $3.06 per unit. In April 2020, each outstanding Class B common unit was converted into a number of shares of common stock and restricted common stock based upon the IPO price. The restricted common stock issued in respect of Class B common units continues to be subject to vesting in accordance with the vesting schedule that was applicable to such Class B common units. The Company granted 1,160,277 shares of restricted common stock to employees, consultants and directors as part of the conversion. In conjunction with the IPO, the Company also granted 1,970,671 stock options, with a weighted average of $11.97 per share, to purchase shares of common stock to employees and directors who were holders of Class B common units at the time of the incentive unit conversion and in new employee grants. The weighted average fair value of the 2,794,546 stock options granted to employees and directors in the nine months ended September 30, 2020 was $15.11 per share. Total share-based compensation expense related to share based awards was comprised of the following (in thousands): Three Months Ended Nine Months Ended 2020 2019 2020 2019 Research and development expense $ 2,180 $ 95 $ 4,606 $ 224 General and administrative expense 5,069 60 10,653 181 Total share-based compensation expense $ 7,249 $ 155 $ 15,259 $ 405 Total share-based compensation expense includes $187 and $187 of share-based compensation expense for Zentera employees for the three and nine months ended September 30, 2020, respectively, compared to $0 for the same periods in 2019. Share-based compensation expense by type of share-based award (in thousands): Three Months Ended Nine Months Ended 2020 2019 2020 2019 Profit interest award units $ — $ 155 $ 329 $ 405 Stock options 2,212 — 3,814 — RSAs and RSUs 5,037 — 11,116 — $ 7,249 $ 155 $ 15,259 $ 405 The fair value of the Class B common unit awards was estimated using an option pricing model with the following assumptions: Nine Months Ended 2020 2019 Members’ equity value (in thousands) $271,207 $197,041 Threshold amounts (in thousands) $309,824 $143,800 Risk free rate 1.5% 1.5% Volatility 75.0% 75.0% Time to liquidity (in years) 1.1 1.1 - 1.8 Lack of marketability discount 26.5% 18.8% - 26.4% Grant date fair value $3.06 $1.88 - $3.06 The Black-Scholes-Merton option pricing model (“Black-Scholes model) is used to estimate the fair value of each Class B common unit 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 applied 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 was 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, 2020 and 2019, we issued 70,000 and 91,000 Class B common units, respectively. As of September 30, 2020 and December 31, 2019, zero and approximately 1.7 million unvested Class B common units were outstanding, respectively. 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 three and nine months ended September 30, 2020 was determined with the following assumptions: Three Months Ended Nine Months Ended Expected volatility 76.6% - 78.2% 76.6% - 78.2% Average expected term (in years) 5.7 - 6.0 5.7 - 6.0 Risk-free interest rate 0.4% 0.4% - 0.5% Expected dividend yield —% —% 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, 2020 Unrecognized Remaining Stock options $ 38,247 3.54 RSAs $ 2,492 2.43 RSUs $ 17,563 1.15

Commitment and Contingencies

Commitment and Contingencies	9 Months Ended
	Sep. 30, 2020
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. 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, 2020 are as follows (in thousands): Year Operating Leases 2020 $ 256 2021 1,044 2022 661 2023 187 Total minimum lease payments: 2,148 Less: imputed interest (246) Total operating lease liabilities 1,902

Net Loss Per Common Share_Class

Net Loss Per Common Share/Class A Common Unit	9 Months Ended
	Sep. 30, 2020
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 2020 2019 2020 2019 Numerator: Net loss attributable to Zentalis $ (34,555) $ (12,344) $ (77,538) $ (31,157) Denominator: Weighted average number of common shares/Class A common units outstanding, basic and diluted 37,959 5,601 24,143 5,601 Net loss per common share $ (0.91) $ — $ (3.21) $ — Net loss per Class A common unit $ — $ (2.20) $ — $ (5.56) Our potential and dilutive securities, which include outstanding stock options, unvested RSAs, unvested RSUs and preferred units, have been excluded from the computation of diluted net loss per common share/Class A common unit as the effect would be anti-dilutive. We considered the impact of presenting a separate earnings per unit calculation for Class B common units. However, as earnings and losses are only allocable to Class B common units after the applicable threshold has been met, and such thresholds have not been met for earnings per unit purposes, no losses were allocated to Class B common units. The following common stock/Class A common unit equivalents have been excluded from the calculations of diluted net loss per common share/Class A common unit because their inclusion would be antidilutive (in thousands). September 30, 2020 2019 Preferred units, as if converted to Class A common units — 9,950 Incentive units—Class B common units — 1,947 Outstanding stock options 2,783 — Unvested RSAs 845 — Unvested RSUs 1,102 — 4,730 11,897

Related Party Disclosures

Related Party Disclosures	9 Months Ended
	Sep. 30, 2020
Related Party Transactions [Abstract]
Related Party Disclosures	Related Party Disclosures On December 21, 2017, we acquired 17,307,692 shares of Series B preferred stock of Kalyra 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 and based on Recurium Equity, LLC’s equity ownership stake in us, as determined in accordance with terms of the license agreement, at the time the milestone is earned. Recurium Equity, LLC (“Recurium Equity”) is also an entity with common ownership to Kalyra prior to the Zentalis investment. In addition, the Company shall pay low to mid-single digit percentage royalties on net product sales to Recurium IP and sublicense fees on any consideration paid to us by a sublicensor. The royalty payments are also based on Recurium Equity’s then equity ownership in us, as determined in accordance with the terms of the license agreement. The license agreement will terminate upon the later of the last expiration of the patent rights or 15 years from the date of commencement. The Master Services Agreement 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, 2020 and 2019, we did not incur any expense with Kalyra. For the nine months ended September 30, 2020 and 2019, we incurred approximately zero and zero dollars of expense with Kalyra, respectively, that was eliminated in consolidation for research and development services provided. As of September 30, 2020 and 2019, there was no balance due to Kalyra. We entered into an Intercompany Services Agreement 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 each of the three months ended September 30, 2020 and 2019, we provided $0.1 million o f research and development services to Kalyra that we eliminated in consolidation. For the nine months ended September 30, 2020 and 2019, we provided $0.3 million and $0.4 million of research and development services to Kalyra that was eliminated in consolidation, respectively. As of September 30, 2020 and 2019, $0.1 million and $0.4 million was due from Kalyra and eliminated in consolidation, respectively.

Interim Unaudited Financial S_2

Interim Unaudited Financial Statements (Policies)	9 Months Ended
	Sep. 30, 2020
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 should be read in conjunction with the Company’s audited financial statements for the year ended December 31, 2019 included in the Company’s final prospectus for its IPO, filed pursuant to Rule 424(b) under the Securities Exchange Act of 1933, as amended, with the SEC on April 6, 2020. 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 the accounts of our wholly owned subsidiaries, majority-owned or controlled companies, and variable interest entity (“VIE”), Kalyra Pharmaceuticals, Inc. (“Kalyra”), for which we are the primary beneficiary. All intercompany transactions and balances have been eliminated in consolidation. Noncontrolling Interest
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.
Marketable Securities	Marketable Securities Marketable securities are investments with original maturities of more than ninety days from the date of purchase that we have the ability to liquidate to fund current operations. Accordingly, those investments with contractual maturities greater than one year from the date of purchase are classified as short-term investments on the accompanying condensed consolidated balance sheets Marketable securities are considered available-for-sale and are carried at fair value with unrealized gains and losses recorded in other comprehensive income (loss) and included as a separate component of stockholders’ deficit. The cost of marketable securities is adjusted for amortization of premiums or accretion of discounts to maturity, and such amortization or accretion is included in investment and other income, net in the interim unaudited condensed consolidated statements of operations. We assess whether our available-for-sale debt securities in an unrealized loss position have credit-related losses and record such losses, and any subsequent improvements as interest income, through an allowance account. We use the specific identification method for calculating realized gains and losses on marketable securities sold. Realized gains and losses on marketable securities, if any, are included in investment and other income, net in the interim unaudited condensed consolidated statements of operations.
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 March 2020, the FASB issued ASU 2020-03, Codification Improvements to Financial Instruments This guidance makes improvements to financial instruments guidance, including the current expected credit losses guidance. January 1, 2020 We have adopted the new guidance as of January 1, 2020. The impact of the adoption was not material to the consolidated financial statements. 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 We currently do not hold equity securities, have equity method investments or derivatives. We do not believe the adoption will have a material impact on our consolidated financial position or results of operations. In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments. In November 2018 and April and May of 2019, the FASB issued additional guidance related to Topic 326. The standard amends the impairment model by requiring entities to use a forward-looking approach based on expected losses to estimate credit losses for most financial assets and certain other instruments that aren’t measured at fair value through net income. January 1, 2020 We have adopted the new guidance on January 1, 2020. The impact of the adoption was not material to the consolidated financial statements. In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes. The new guidance is intended to simplify aspects of the accounting for income taxes, including the elimination of certain exceptions to the guidance in ASC 740 related to the approach for intraperiod tax allocation, among other changes. January 1, 2020 We have adopted the new guidance on January 1, 2020. The impact of the adoption was not material to the consolidated financial statements.

Interim Unaudited Financial S_3

Interim Unaudited Financial Statements (Tables)	9 Months Ended
	Sep. 30, 2020
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 March 2020, the FASB issued ASU 2020-03, Codification Improvements to Financial Instruments This guidance makes improvements to financial instruments guidance, including the current expected credit losses guidance. January 1, 2020 We have adopted the new guidance as of January 1, 2020. The impact of the adoption was not material to the consolidated financial statements. 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 We currently do not hold equity securities, have equity method investments or derivatives. We do not believe the adoption will have a material impact on our consolidated financial position or results of operations. In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments. In November 2018 and April and May of 2019, the FASB issued additional guidance related to Topic 326. The standard amends the impairment model by requiring entities to use a forward-looking approach based on expected losses to estimate credit losses for most financial assets and certain other instruments that aren’t measured at fair value through net income. January 1, 2020 We have adopted the new guidance on January 1, 2020. The impact of the adoption was not material to the consolidated financial statements. In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes. The new guidance is intended to simplify aspects of the accounting for income taxes, including the elimination of certain exceptions to the guidance in ASC 740 related to the approach for intraperiod tax allocation, among other changes. January 1, 2020 We have adopted the new guidance on January 1, 2020. The impact of the adoption was not material to the consolidated financial statements.

Business Combinations (Tables)

Business Combinations (Tables)	9 Months Ended
	Sep. 30, 2020
Business Combinations [Abstract]
Schedule of Assets and Liabilities of VIE	Total assets and liabilities of Kalyra as of September 30, 2020 and December 31, 2019 are as follows (in thousands): September 30, December 31, 2020 2019 Cash and cash equivalents $ 417 $ 712 Other current assets 31 21 In-process research and development 8,800 8,800 Goodwill 3,736 3,736 Other long-term assets 14 14 Accounts payable and accrued expenses 87 391 Deferred tax liability 2,463 2,463 Noncontrolling interests $ 6,635 $ 6,821
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, 2020 Noncontrolling interest at beginning of period $ 6,821 Net loss attributable to noncontrolling interest (186) Noncontrolling interest at end of period $ 6,635

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Components of Available-for-sale Marketable Securities	Available-for-sale marketable securities consisted of the following (in thousands): September 30, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper $ 125,748 $ 9 $ (7) $ 125,750 Corporate debt securities 31,840 5 (3) 31,842 US government agencies 77,523 22 (5) 77,540 US Treasury securities 39,750 3 (1) 39,752 $ 274,861 $ 39 $ (16) $ 274,884
Contractual Maturities of Available-for-sale Debt Securities	Contractual maturities of available-for-sale debt securities are as follows (in thousands): September 30, 2020 Estimated Fair Value Due within one year $ 239,291 After one but within five years 35,593 $ 274,884
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, 2020 December 31, 2019 Level 1 Level 2 Total estimated fair value Level 1 Level 2 Total estimated fair value Cash equivalents: Money market funds $ 29,924 $ — $ 29,924 $ 62,961 $ — $ 62,961 US government agencies — 2,631 2,631 — — — US Treasury securities 9,999 — 9,999 — — — Corporate debt securities — 14,999 14,999 — — — Total cash equivalents: 39,923 17,630 57,553 62,961 — 62,961 Available-for-sale marketable securities: Commercial paper — 125,750 125,750 — — — Corporate debt securities — 31,842 31,842 — — — US government agencies — 77,540 77,540 — — — US Treasury securities 39,752 — 39,752 — — — Total available-for-sale marketable securities: 39,752 235,132 274,884 — — — Total assets measured at fair value $ 79,675 $ 252,762 $ 332,437 $ 62,961 $ — $ 62,961

Prepaid Expenses and Other As_2

Prepaid Expenses and Other Assets (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 2019 Prepaid insurance $ 1,761 $ 150 Prepaid software licenses and maintenance 320 238 Prepaid research and development expenses 5,735 2,985 Interest receivable 511 — Upfront lease payment 810 — Other prepaid expenses 286 266 Total prepaid expenses and other current assets 9,423 3,639 Less long-term portion 4,245 2,134 Total prepaid expenses and other assets, current $ 5,178 $ 1,505

Property and Equipment, net (Ta

Property and Equipment, net (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 2019 Computer and office equipment $ 291 $ 243 Lab equipment 360 401 Leasehold improvements 43 24 Construction in progress 6 — Subtotal 700 668 Accumulated depreciation and amortization (229) (167) Property and equipment, net $ 471 $ 501 Depreciation and amortization expense for the three months ended September 30, 2020 and 2019 was approximately fifty-one thousand and twenty-five thousand, respectively. Depreciation and amortization expense for the nine months ended September 30, 2020

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2020
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consist of the following (in thousands): September 30, December 31, 2020 2019 Accrued research and development expenses $ 10,618 $ 5,465 Accrued employee expenses 4,390 2,977 Accrued general and administrative expenses 2,571 1,356 Lease liability 871 781 Other 19 29 Total accrued expenses $ 18,469 $ 10,608

Convertible Preferred Units (Ta

Convertible Preferred Units (Tables)	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
Schedule of Temporary Equity	There were no authorized, issued, and outstanding shares of convertible preferred units at September 30, 2020. As of December 31, 2019, the authorized, issued, and outstanding units of convertible preferred units were as follows (in thousands, except unit amounts): December 31, 2019 Series Units Units Issued Liquidation Carrying Series A convertible preferred units 1,579,309 1,579,309 $ 18,320 $ 18,226 Series B convertible preferred units 3,523,739 3,523,739 43,800 41,604 Series C convertible preferred units 5,714,300 4,847,106 84,824 81,876 Total 10,817,348 9,950,154 $ 146,944 $ 141,706

Equity and Share-based Compen_2

Equity and Share-based Compensation (Tables)	9 Months Ended
	Sep. 30, 2020
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 2020 2019 2020 2019 Research and development expense $ 2,180 $ 95 $ 4,606 $ 224 General and administrative expense 5,069 60 10,653 181 Total share-based compensation expense $ 7,249 $ 155 $ 15,259 $ 405 Share-based compensation expense by type of share-based award (in thousands): Three Months Ended Nine Months Ended 2020 2019 2020 2019 Profit interest award units $ — $ 155 $ 329 $ 405 Stock options 2,212 — 3,814 — RSAs and RSUs 5,037 — 11,116 — $ 7,249 $ 155 $ 15,259 $ 405
Schedule of Valuation Assumptions	The fair value of the Class B common unit awards was estimated using an option pricing model with the following assumptions: Nine Months Ended 2020 2019 Members’ equity value (in thousands) $271,207 $197,041 Threshold amounts (in thousands) $309,824 $143,800 Risk free rate 1.5% 1.5% Volatility 75.0% 75.0% Time to liquidity (in years) 1.1 1.1 - 1.8 Lack of marketability discount 26.5% 18.8% - 26.4% Grant date fair value $3.06 $1.88 - $3.06 Three Months Ended Nine Months Ended Expected volatility 76.6% - 78.2% 76.6% - 78.2% Average expected term (in years) 5.7 - 6.0 5.7 - 6.0 Risk-free interest rate 0.4% 0.4% - 0.5% 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, 2020 Unrecognized Remaining Stock options $ 38,247 3.54 RSAs $ 2,492 2.43 RSUs $ 17,563 1.15

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Operating Lease Payments	Approximate annual future minimum operating lease payments as of September 30, 2020 are as follows (in thousands): Year Operating Leases 2020 $ 256 2021 1,044 2022 661 2023 187 Total minimum lease payments: 2,148 Less: imputed interest (246) Total operating lease liabilities 1,902

Net Loss Per Common Share_Cla_2

Net Loss Per Common Share/Class A Common Unit (Tables)	9 Months Ended
	Sep. 30, 2020
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 2020 2019 2020 2019 Numerator: Net loss attributable to Zentalis $ (34,555) $ (12,344) $ (77,538) $ (31,157) Denominator: Weighted average number of common shares/Class A common units outstanding, basic and diluted 37,959 5,601 24,143 5,601 Net loss per common share $ (0.91) $ — $ (3.21) $ — Net loss per Class A common unit $ — $ (2.20) $ — $ (5.56)
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Unit	The following common stock/Class A common unit equivalents have been excluded from the calculations of diluted net loss per common share/Class A common unit because their inclusion would be antidilutive (in thousands). September 30, 2020 2019 Preferred units, as if converted to Class A common units — 9,950 Incentive units—Class B common units — 1,947 Outstanding stock options 2,783 — Unvested RSAs 845 — Unvested RSUs 1,102 — 4,730 11,897

Organization and Business (Deta

Organization and Business (Details) $ / shares in Units, $ in Thousands	Aug. 03, 2020USD ($)$ / sharesshares	May 19, 2020USD ($)executive	Apr. 07, 2020USD ($)$ / sharesshares	Apr. 02, 2020$ / sharesshares	Dec. 21, 2017	Sep. 30, 2015USD ($)	Mar. 31, 2016USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)
Class of Stock [Line Items]
Exchange ratio					1
Proceeds from issuance of common stock in initial public offering, net			$ 190,000					$ 172,482	$ 0
Issuance fees and expenses			17,600
Contributions from noncontrolling interest owners		$ 20,000						$ 18,424
Zentera Stock Plan
Class of Stock [Line Items]
Number of executives entering restricted stock agreement | executive		2
RSAs | Zentera Stock Plan
Class of Stock [Line Items]
Restricted stock vesting period (in years)		4 years
Zentera Sublicenses
Class of Stock [Line Items]
Ownership percentage								60.20%
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
Follow-On Offering
Class of Stock [Line Items]
Gross proceeds from issuance of common stock	$ 166,000
Expenses and Fees from the Issuance of Common Stock	$ 10,800
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	618,750		1,377,000
Common Stock | Follow-On Offering
Class of Stock [Line Items]
Share price (in dollars per sharee) | $ / shares	$ 35
Number of shares issued and sold (in shares) | shares	4,743,750
RSAs | IPO
Class of Stock [Line Items]
Number of shares converted (in shares) | shares				1,160,277
Series A Preferred Units
Class of Stock [Line Items]
Issuance fees and expenses		$ 1,600				$ 100	$ 39

Business Combinations - Narrati

Business Combinations - Narrative (Details) - Kalyra Pharmaceuticals, Inc. $ in Millions	Dec. 21, 2017USD ($)
Variable Interest Entity [Line Items]
Cash payments to acquire interest	$ 4.5
Ownership percentage	25.00%

Business Combinations - Assets

Business Combinations - Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 92,552	$ 67,246	$ 80,526
In-process research and development	8,800	8,800
Goodwill	3,736	3,736
Deferred tax liability	2,463	2,463
VIE, Primary Beneficiary
Variable Interest Entity [Line Items]
Cash and cash equivalents	417	712
Other current assets	31	21
In-process research and development	8,800	8,800
Goodwill	3,736	3,736
Other long-term assets	14	14
Accounts payable and accrued expenses	87	391
Deferred tax liability	2,463	2,463
Noncontrolling interests	$ 6,635	$ 6,821

Business Combinations - Rollfor

Business Combinations - Rollforward of Noncontrolling Interest (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Net loss attributable to noncontrolling interests	$ (110)	$ (228)	$ (654)	$ (675)
VIE, Primary Beneficiary
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Noncontrolling interest at beginning of period			6,821
Net loss attributable to noncontrolling interests			(186)
Noncontrolling interest at end of period	$ 6,635		$ 6,635

Fair Value Measurement - Compon

Fair Value Measurement - Components of Available-for-sale Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 274,861
Gross Unrealized Gains	39
Gross Unrealized Losses	(16)
Debt securities, available-for-sale, fair value	274,884	$ 0
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	125,748
Gross Unrealized Gains	9
Gross Unrealized Losses	(7)
Debt securities, available-for-sale, fair value	125,750	0
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	31,840
Gross Unrealized Gains	5
Gross Unrealized Losses	(3)
Debt securities, available-for-sale, fair value	31,842	0
US government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	77,523
Gross Unrealized Gains	22
Gross Unrealized Losses	(5)
Debt securities, available-for-sale, fair value	77,540	0
US Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	39,750
Gross Unrealized Gains	3
Gross Unrealized Losses	(1)
Debt securities, available-for-sale, fair value	$ 39,752	$ 0

Fair Value Measurement - Narrat

Fair Value Measurement - Narrative (Details) $ in Thousands	Sep. 30, 2020USD ($)security
Fair Value Disclosures [Abstract]
Number of available-for-sale securities in unrealized loss position | security	19
Debt securities fair market value	$ 85,300
Fair value of available-for-sale securities in unrealized loss position	$ 16

Fair Value Measurement - Contra

Fair Value Measurement - Contractual Maturities of Available-for-sale Securities (Details) $ in Thousands	Sep. 30, 2020USD ($)
Fair Value Disclosures [Abstract]
Due within one year	$ 239,291
After one but within five years	35,593
Amortized Cost	$ 274,884

Fair Value Measurement - Fair V

Fair Value Measurement - Fair Value of Assets Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	$ 57,553	$ 62,961
Marketable securities, available-for-sale	274,884	0
Total fair value of assets	332,437	62,961
Fair Value, Inputs, Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	39,923	62,961
Marketable securities, available-for-sale	39,752	0
Total fair value of assets	79,675	62,961
Fair Value, Inputs, Level 2
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	17,630	0
Marketable securities, available-for-sale	235,132	0
Total fair value of assets	252,762	0
Commercial paper
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable securities, available-for-sale	125,750	0
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	125,750	0
Corporate debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable securities, available-for-sale	31,842	0
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	31,842	0
US government agencies
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable securities, available-for-sale	77,540	0
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	77,540	0
US Treasury securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Marketable securities, available-for-sale	39,752	0
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	39,752	0
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	29,924	62,961
Money market funds | Fair Value, Inputs, Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	29,924	62,961
Money market funds | Fair Value, Inputs, Level 2
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	0	0
US government agencies
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	2,631	0
US government agencies | Fair Value, Inputs, Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	0	0
US government agencies | Fair Value, Inputs, Level 2
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	2,631	0
US Treasury securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	9,999	0
US Treasury securities | Fair Value, Inputs, Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Cash equivalents	9,999	0
US Treasury securities | 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	14,999	0
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	$ 14,999	$ 0

Prepaid Expenses and Other As_3

Prepaid Expenses and Other Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid insurance	$ 1,761	$ 150
Prepaid software licenses and maintenance	320	238
Prepaid research and development expenses	5,735	2,985
Interest receivable	511	0
Upfront lease payment	810	0
Other prepaid expenses	286	266
Total prepaid expenses and other current assets	9,423	3,639
Less long-term portion	4,245	2,134
Total prepaid expenses and other assets, current	$ 5,178	$ 1,505

Property and Equipment, net - S

Property and Equipment, net - Summary (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Subtotal	$ 700	$ 668
Accumulated depreciation and amortization	(229)	(167)
Property and equipment, net	471	501
Computer and office equipment
Property, Plant and Equipment [Line Items]
Subtotal	291	243
Lab equipment
Property, Plant and Equipment [Line Items]
Subtotal	360	401
Leasehold improvements
Property, Plant and Equipment [Line Items]
Subtotal	43	24
Construction in progress
Property, Plant and Equipment [Line Items]
Subtotal	$ 6	$ 0

Property and Equipment, net - N

Property and Equipment, net - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Property, Plant and Equipment [Abstract]
Depreciation and amortization	$ 51	$ 25	$ 127	$ 70

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Accrued research and development expenses	$ 10,618	$ 5,465
Accrued employee expenses	4,390	2,977
Accrued general and administrative expenses	2,571	1,356
Lease liability	871	781
Other	19	29
Total accrued expenses	$ 18,469	$ 10,608

Convertible Preferred Units - N

Convertible Preferred Units - Narrative (Details) - USD ($)	May 19, 2020	Apr. 07, 2020	Feb. 29, 2020	Sep. 30, 2019	Dec. 31, 2017	Sep. 30, 2015	Mar. 31, 2016	Apr. 02, 2020	Aug. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Class of Stock [Line Items]
Convertible preferred units issued (in shares)										867,000
Shares issued (in shares)												9,950,154
Net proceeds from issuance of convertible preferred units										$ 14,228,000	$ 81,883,000
Issuance costs of financing		$ 17,600,000
Dividends declared								$ 0
Automatic conversion feature, minimum gross cash proceeds received in a public offering										$ 75,000,000
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					1,579,309
Gross proceeds from issuance of convertible preferred units						$ 15,000,000	$ 3,300,000
Net proceeds from issuance of convertible preferred units						14,900,000
Issuance costs of financing	$ 1,600,000					$ 100,000	$ 39,000
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			3,523,739
Gross proceeds from issuance of convertible preferred units					$ 34,000,000				$ 9,800,000
Net proceeds from issuance of convertible preferred units					32,100,000				9,500,000
Issuance costs of financing					$ 1,900,000				$ 300,000
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						17.50	$ 17.50
Shares issued (in shares)			867,194	4,847,106							4,847,106	4,847,106
Gross proceeds from issuance of convertible preferred units			$ 15,200,000	$ 84,800,000
Net proceeds from issuance of convertible preferred units			14,200,000	81,900,000
Issuance costs of financing			$ 1,000,000	$ 2,900,000
Conversion price (in dollars per share)										17.50
Liquidation preference (in dollars per share)										$ 17.50

Convertible Preferred Units - S

Convertible Preferred Units - Schedule of Units Authorized, Issued, and Outstanding (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Feb. 29, 2020	Dec. 31, 2019	Sep. 30, 2019	Aug. 31, 2018	Dec. 31, 2017	Mar. 31, 2016
Class of Stock [Line Items]
Units authorized (in shares)			10,817,348
Shares issued (in shares)			9,950,154
Shares outstanding (in shares)			9,950,154
Liquidation Value			$ 146,944
Carrying Value	$ 0		$ 141,706
Series A Preferred Units
Class of Stock [Line Items]
Units authorized (in shares)			1,579,309
Shares issued (in shares)			1,579,309				286,205
Shares outstanding (in shares)			1,579,309
Liquidation Value			$ 18,320
Carrying Value			$ 18,226
Series B Preferred Units
Class of Stock [Line Items]
Units authorized (in shares)			3,523,739
Shares issued (in shares)			3,523,739		788,419	2,735,320
Shares outstanding (in shares)			3,523,739
Liquidation Value			$ 43,800
Carrying Value			$ 41,604
Series C Preferred Units
Class of Stock [Line Items]
Units authorized (in shares)			5,714,300
Shares issued (in shares)		867,194	4,847,106	4,847,106
Shares outstanding (in shares)			4,847,106
Liquidation Value			$ 84,824
Carrying Value			$ 81,876

Equity and Share-based Compen_3

Equity and Share-based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	Aug. 03, 2020	May 19, 2020	Apr. 07, 2020	Apr. 02, 2020	Apr. 30, 2020	Dec. 31, 2017	Sep. 30, 2015	Mar. 31, 2016	Sep. 30, 2020	Sep. 30, 2019	Aug. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 21, 2017
Class of Stock [Line Items]
Common stock issued (in shares)						5,187,554			40,614,453			40,614,453
Common stock outstanding (in shares)						5,187,554			40,614,453			40,614,453
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									$ 172,482	$ 0
Issuance fees and expenses			17,600
Options granted (in shares)					1,970,671							2,794,546
Weighted-average grant date fair value of options (in usd per share)					$ 11.97							$ 15.11
Share-based compensation expense									$ 7,249	$ 155		$ 15,259	405
Shares issued upon vesting of certain RSAs (in shares)												309,010
Options number outstanding									2.8			2.8
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
Issuance fees and expenses			$ 17,600
Zentera Stock Plan
Class of Stock [Line Items]
Employee benefits and share-based compensation									$ 187			$ 187
Share-based compensation expense										$ 0			$ 0
Series A Preferred Units
Class of Stock [Line Items]
Preferred units authorized (in shares)						1,638,000
Issuance fees and expenses		$ 1,600					$ 100	$ 39
Series B Preferred Units
Class of Stock [Line Items]
Preferred units authorized (in shares)						3,621,000
Issuance fees and expenses						$ 1,900					$ 300
Class A Common Units
Class of Stock [Line Items]
Common units, authorized (in shares)						15,000,000				20,000,000			20,000,000	20,000,000
Stock issued (in shares)									0	0				7,093
Common units subject to future vesting conditions (in shares)									0	9,572		0	9,572	9,572
Class B Common Units
Class of Stock [Line Items]
Common units, authorized (in shares)						872,620				3,458,522			3,458,522	3,458,522
Stock issued (in shares)												70,000	91,000
Stock issued upon conversion of units (in shares)						703,000
Awards granted (in shares)												70,000
Grant date fair value (USD per share)												$ 3.06
Unvested common units outstanding (in shares)									0			0		1,700,000
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 | Corporate Conversion
Class of Stock [Line Items]
Stock issued (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)	618,750		1,377,000
Share price (in dollars per sharee)			$ 18
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%
RSAs | IPO
Class of Stock [Line Items]
Stock issued upon conversion of units (in shares)				1,160,277
RSAs
Class of Stock [Line Items]
Awards granted (in shares)					1,160,277
Stock options
Class of Stock [Line Items]
Share-based compensation expense									$ 2,212	$ 0		$ 3,814	$ 0
Generally expected vesting term of the option contract (in years)												10 years
RSUs
Class of Stock [Line Items]
Non-Option equity Instruments, outstanding									1,100,000			1,100,000
Restricted Stock Award
Class of Stock [Line Items]
Non-Option equity Instruments, outstanding									800,000			800,000

Equity and Share-based Compen_4

Equity and Share-based Compensation - Share-based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 7,249	$ 155	$ 15,259	$ 405
Research and development expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	2,180	95	4,606	224
General and administrative expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 5,069	$ 60	$ 10,653	$ 181

Equity and Share-based Compen_5

Equity and Share-based Compensation - Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 7,249	$ 155	$ 15,259	$ 405
Profit interest award units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	0	155	329	405
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	2,212	0	3,814	0
RSAs and RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 5,037	$ 0	$ 11,116	$ 0

Equity and Share-based Compen_6

Equity and Share-based Compensation - Fair Value Assumptions for Profit Interest Awards (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Members’ equity value (in thousands)	$ 341,055		$ (80,106)
Profit Interest Awards
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Members’ equity value (in thousands)	271,207	$ 197,041
Threshold amounts (in thousands)	$ 309,824	$ 143,800
Risk free rate (as a percent)	1.50%	1.50%
Volatility (as a percent)	75.00%	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)	$ 3.06
Profit Interest Awards | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Time to liquidity (in years)		1 year 1 month 6 days
Lack of marketability discount (as a percent)		18.80%
Grant date fair value (USD per share)		$ 1.88
Profit Interest Awards | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Time to liquidity (in years)		1 year 9 months 18 days
Lack of marketability discount (as a percent)		26.40%
Grant date fair value (USD per share)		$ 3.06

Equity and Share-based Compen_7

Equity and Share-based Compensation - Fair Value Assumptions for Stock Options (Details) - Stock options	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Risk free rate (as a percent)	0.40%
Expected dividend yield	0.00%	0.00%
Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Volatility (as a percent)	76.60%	76.60%
Average expected term (in years)	5 years 8 months 12 days	5 years 8 months 12 days
Risk free rate (as a percent)		0.40%
Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Volatility (as a percent)	78.20%	78.20%
Average expected term (in years)	6 years	6 years
Risk free rate (as a percent)		0.50%

Equity and Share-based Compen_8

Equity and Share-based Compensation - Unrecognized Compensation Cost (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized expense, stock options	$ 38,247
Remaining Weighted-Average Recognition Period (years)	3 years 6 months 14 days
RSAs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized expense, other than options	$ 2,492
Remaining Weighted-Average Recognition Period (years)	2 years 5 months 4 days
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized expense, other than options	$ 17,563
Remaining Weighted-Average Recognition Period (years)	1 year 1 month 24 days

Commitment and Contingencies -

Commitment and Contingencies - Future Minimum Lease Payments (Details) $ in Thousands	Sep. 30, 2020USD ($)
Commitments and Contingencies Disclosure [Abstract]
2020	$ 256
2021	1,044
2022	661
2023	187
Total minimum lease payments:	2,148
Less: imputed interest	(246)
Total operating lease liabilities	$ 1,902

Commitment and Contingencies _2

Commitment and Contingencies - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2020	Sep. 30, 2020
Lessee, Lease, Description [Line Items]
Operating lease, weighted-average remaining lease term (in years)		2 years
Real Estate, 10.7 Year Lease Term | Forecast
Lessee, Lease, Description [Line Items]
Total minimum lease payments on leases not yet commenced	$ 86.5
Operating leases not yet commenced, term (in years)	10 years 8 months 12 days
Real Estate, 1.2 Year Lease Term | Forecast
Lessee, Lease, Description [Line Items]
Total minimum lease payments on leases not yet commenced	$ 0.1
Operating leases not yet commenced, term (in years)	1 year 2 months 12 days

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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net loss attributable to Zentalis	$ (34,555)	$ (12,344)	$ (77,538)	$ (31,157)
Denominator:
Weighted average number of Class A common units outstanding, basic and diluted (in shares)	37,959	5,601	24,143	5,601
Common Stock
Denominator:
Net loss per Class A common unit (USD per share)	$ (0.91)	$ 0	$ (3.21)	$ 0
Class A Common Units
Denominator:
Net loss per Class A common unit (USD per share)	$ 0	$ (2.20)	$ 0	$ (5.56)

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, 2020	Sep. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per unit (in shares)	4,730	11,897
Preferred units, as if converted to Class A common units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per unit (in shares)	0	9,950
Incentive units—Class B common units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per unit (in shares)	0	1,947
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per unit (in shares)	2,783	0
RSAs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per unit (in shares)	845	0
RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per unit (in shares)	1,102	0

Related Party Disclosures (Deta

Related Party Disclosures (Details) - USD ($)	Jun. 01, 2020	Dec. 21, 2017	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Related Party Transaction [Line Items]
Number of shares acquired (in shares)			0		0
Capital Addition Purchase Commitments
Related Party Transaction [Line Items]
Equipment purchase and sale agreement	$ 400,000
Affiliated Entity | Master Services Agreement
Related Party Transaction [Line Items]
Expenses from transactions with related party			$ 0	$ 0	$ 0	$ 0
Affiliated Entity | Intercompany Services Agreement
Related Party Transaction [Line Items]
Revenue from related parties			100,000	100,000	300,000	400,000
Due from related parties			$ 100,000	$ 400,000	$ 100,000	$ 400,000
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 (in years)						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

Uncategorized Items - zntl-2020

Label	Element	Value
Restricted Cash, Noncurrent	us-gaap_RestrictedCashNoncurrent	$ 243,000
Restricted Cash, Noncurrent	us-gaap_RestrictedCashNoncurrent	$ 1,320,000