Zentalis Pharmaceuticals (ZNTL) S-1 27 Jul 20 IPO registration Financial data

Cover

Cover	3 Months Ended
	Mar. 31, 2020
Cover [Abstract]
Document Type	S-1
Amendment Flag	false
Entity Registrant Name	Zentalis Pharmaceuticals, Inc.
Entity Central Index Key	0001725160
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($)	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 63,650,000	$ 67,246,000	$ 25,154,000
Accounts receivable from government grants, net	139,000	140,000	917,000
Prepaid expenses and other current assets	2,220,000	1,505,000	606,000
Total current assets	66,009,000	68,891,000	26,677,000
Property and equipment, net	519,000	501,000	260,000
Operating lease right-of-use assets	2,276,000	2,335,000
Prepaid expenses and other assets	2,353,000	2,134,000	1,525,000
Deferred financing costs	3,525,000	841,000
Goodwill	3,736,000	3,736,000	3,736,000
In-process research and development	8,800,000	8,800,000	8,800,000
Restricted cash	411,000	243,000
Total assets	87,629,000	87,481,000	40,998,000
Current Liabilities
Accounts payable	7,019,000	4,289,000	3,431,000
Accrued expenses	9,920,000	10,608,000	2,554,000
Deferred grant proceeds			223,000
Total current liabilities	16,939,000	14,897,000	6,208,000
Deferred tax liability	2,463,000	2,463,000	2,463,000
Other long-term liabilities	1,484,000	1,700,000	21,000
Total liabilities	20,886,000	19,060,000	8,692,000
Commitments and contingencies
Convertible preferred units; Redemption value of $162,120,000 and $146,944,000 at March 31, 2020 and December 31, 2019, respectively	155,934,207	141,705,846
LIABILITIES, CONVERTIBLE PREFERRED UNITS AND DEFICIT
Common Stock, $0.001 par value per share; no shares authorized, issued and outstanding at December 31, 2018 and 2019, respectively; 250,000,000 shares authorized, 25,321,524 shares issued and 24,147,270 shares outstanding, pro forma (unaudited)		0	0
Accumulated deficit	(99,119,000)	(82,993,000)	(37,330,000)
Total Zentalis Pharmaceuticals, LLC members' deficit	(95,903,000)	(80,106,000)	24,770,000
Noncontrolling interests	6,712,000	6,821,000	7,536,000
Total deficit	(89,191,000)	(73,285,000)	32,306,000
Total liabilities, convertible preferred units and deficit	87,629,000	87,481,000	40,998,000
Class A Common Units
LIABILITIES, CONVERTIBLE PREFERRED UNITS AND DEFICIT
Class A and B common units	709,000	709,000	672,000
Class B Common Units
LIABILITIES, CONVERTIBLE PREFERRED UNITS AND DEFICIT
Class A and B common units	$ 2,507,000	$ 2,178,000	1,598,000
Convertible Preferred Units
LIABILITIES, CONVERTIBLE PREFERRED UNITS AND DEFICIT
Preferred stock			$ 59,829,754

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($)	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Convertible preferred units, redemption value	$ 162,120,000	$ 146,944,000
Common Stock, par value		$ 0.001	$ 0.001
Common Stock, shares authorized		250,000,000	250,000,000
Common Stock, shares issued		25,321,524	25,321,524
Common Stock, shares outstanding		24,147,270	24,147,270
Pro Forma
Preferred Stock, par value		$ 0.001	$ 0.001
Preferred Stock, shares authorized		10,000,000	10,000,000
Preferred Stock, shares issued		0	0
Preferred Stock, shares outstanding		0	0
Class A Common Units
Common units, authorized (in shares)	20,000,000	20,000,000	15,000,000
Common units, issued (in shares)	5,601,478	5,601,478	5,594,385
Common units, outstanding (in shares)	5,601,478	5,601,478	5,594,385
Class B Common Units
Common units, authorized (in shares)	3,458,522	3,458,522	2,154,816
Common units, issued (in shares)	2,607,309	2,670,668	1,612,311
Common units, outstanding (in shares)	2,607,309	2,670,668	1,612,311
Convertible Preferred Units
Preferred stock, redemption value			$ 62,120,000
Preferred Stock, shares authorized			5,259,000
Preferred Stock, shares issued			5,103,048
Preferred Stock, shares outstanding			5,103,048

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Revenue				$ 14
Operating Expenses
Research and development	$ 13,258	$ 7,089	$ 38,386	18,921
General and administrative	3,141	1,633	8,459	4,876
Total operating expenses	16,399	8,722	46,845	23,797
Operating loss	(16,399)	(8,722)	(46,845)	(23,783)
Other Income (Expense)
Interest income	164	74	498	355
Other expense	0	(12)	(16)	0
Net loss before income taxes	(16,235)	(8,660)	(46,363)	(23,428)
Income tax expense	0	3	15	4
Net loss	(16,235)	(8,663)	(46,378)	(23,432)
Net loss attributable to noncontrolling interests	(109)	(320)	(715)	(2,365)
Net loss attributable to Zentalis Pharmaceuticals, LLC	$ (16,126)	$ (8,343)	$ (45,663)	$ (21,067)
Net loss per Class A common units outstanding, basic and diluted (USD per share)	$ (2.88)	$ (1.49)	$ (8.16)	$ (3.77)
Units used in computing net loss per Class A common unit, basic and diluted (in shares)	5,601	5,594	5,597	5,594

Condensed Consolidated Changes

Condensed Consolidated Changes in Redeemable Preferred Stock and Stockholders' Deficit - USD ($)	Total	Class A Common Units	Class B Common Units	Preferred StockConvertible Preferred Units	Common StockClass A Common Units	Common StockClass B Common Units	Accumulated Deficit	Total Zentalis Pharmaveuticals, LLC Members' Equity (Deficit)	Noncontrolling Interests
Beginning balance, in shares at Dec. 31, 2017				4,314,000
Beginning balance at Dec. 31, 2017	$ 45,096,000			$ 50,374,000			$ (17,125,000)	$ 35,211,000	$ 9,885,000
Common units, beginning balance (in shares) at Dec. 31, 2017					5,594,000	703,000
Common units, beginning balance at Dec. 31, 2017					$ 643,000	$ 1,319,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment from adoption of ASU 2014-09	862,000						862,000	862,000
Issuance of Series B convertible preferred units at $12.43 per unit net of issuance costs	9,456,000			$ 9,456,000				9,456,000
Issuance of Series B convertible preferred units at $12.43 per unit net of issuance costs in shraes				789,000
Issuance of profit interest awards, net		0				909,000
Share-based compensation expense	308,000				$ 29,000	$ 279,000		308,000
Proceeds from exercise of equity awards from consolidated VIE	16,000								16,000
Net loss attributable to noncontrolling interests	(2,365,000)								(2,365,000)
Net loss attributable to Zentalis Pharmaceuticals, LLC	(21,067,000)						(21,067,000)	(21,067,000)
Ending balance, in shares at Dec. 31, 2018				5,103,000
Ending balance at Dec. 31, 2018	32,306,000			$ 59,830,000			(37,330,000)	24,770,000	7,536,000
Common units, ending balance (in shares) at Dec. 31, 2018		5,594,385	1,612,311		5,594,000	1,612,000
Common units, ending balance at Dec. 31, 2018		$ 672,000	$ 1,598,000		$ 672,000	$ 1,598,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of profit interest awards, net			47,500			48,000
Share-based compensation expense	129,000				$ 2,000	$ 127,000		129,000
Net loss attributable to noncontrolling interests	(320,000)								(320,000)
Net loss attributable to Zentalis Pharmaceuticals, LLC	(8,343,000)						(8,343,000)	(8,343,000)
Ending balance, in shares at Mar. 31, 2019				5,103,000
Ending balance at Mar. 31, 2019	(23,592,000)			$ 59,830,000			(45,673,000)	(16,376,000)	7,216,000
Common units, ending balance (in shares) at Mar. 31, 2019					5,594,000	1,660,000
Common units, ending balance at Mar. 31, 2019					$ 674,000	$ 1,725,000
Beginning balance, in shares at Dec. 31, 2018				5,103,000
Beginning balance at Dec. 31, 2018	$ 32,306,000			$ 59,830,000			(37,330,000)	24,770,000	7,536,000
Common units, beginning balance (in shares) at Dec. 31, 2018		5,594,385	1,612,311		5,594,000	1,612,000
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	$ 81,876,000
Reclassification of convertible preferred units for contingent liquidation features not within the Company's control	$ 59,830,000
Reclassification of convertible preferred units for contingent liquidation features not within the Company's control in shares	5,103,000
Common units, beginning balance at Dec. 31, 2018		$ 672,000	$ 1,598,000		$ 672,000	$ 1,598,000
Temporary equity ending balance (in shares) at Dec. 31, 2019	9,950,154
Temporary equity, ending balance at Dec. 31, 2019	$ 141,705,846
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of convertible preferred units for contingent liquidation features not within the Company's control	(59,830,000)			$ (59,830,000)				(59,830,000)
Reclassification of convertible preferred units for contingent liquidation features not within the Company's control, shares				(5,103,000)
Issuance of profit interest awards, net		7,093				1,059,000
Share-based compensation expense	617,000				$ 37,000	$ 580,000		617,000
Share-based compensation expense, shares					7,000
Net loss attributable to noncontrolling interests	(715,000)								(715,000)
Net loss attributable to Zentalis Pharmaceuticals, LLC	(45,663,000)						(45,663,000)	(45,663,000)
Ending balance at Dec. 31, 2019	$ (73,285,000)						(82,993,000)	(80,106,000)	6,821,000
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		$ 709,000	$ 2,178,000		$ 709,000	$ 2,178,000
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	$ 14,228,000
Temporary equity ending balance (in shares) at Mar. 31, 2020	10,817,348
Temporary equity, ending balance at Mar. 31, 2020	$ 155,934,207
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cancellation of profit interest awards, net						(64,000)
Issuance of profit interest awards, net			70,000
Share-based compensation expense	329,000					$ 329,000		329,000
Net loss attributable to noncontrolling interests	(109,000)								(109,000)
Net loss attributable to Zentalis Pharmaceuticals, LLC	(16,126,000)						(16,126,000)	(16,126,000)
Ending balance at Mar. 31, 2020	$ (89,191,000)						$ (99,119,000)	$ (95,903,000)	$ 6,712,000
Common units, ending balance (in shares) at Mar. 31, 2020		5,601,478	2,607,309		5,601,000	2,607,000
Common units, ending balance at Mar. 31, 2020		$ 709,000	$ 2,507,000		$ 709,000	$ 2,507,000

Condensed Consolidated Change_2

Condensed Consolidated Changes in Redeemable Preferred Stock and Stockholders' Deficit (Parenthetical) - $ / shares	Mar. 31, 2020	Feb. 29, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018	Aug. 31, 2018	Dec. 31, 2017
Series C Preferred Units
Par value per share (in dollars per share)	$ 17.5	$ 17.50	$ 17.50	$ 17.50
Series B Preferred Units
Par value per share (in dollars per share)	$ 12.43		$ 12.43		$ 12.43	$ 12.43	$ 12.43

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Operating Activities:
Consolidated net loss	$ (16,235)	$ (8,663)	$ (46,378)	$ (23,432)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	38	21	111	51
Share-based compensation	329	129	617	308
Changes in operating assets and liabilities:
Accounts receivable	1	225	777	(254)
Prepaid expenses and other assets	(1,050)	(230)	(1,508)	(1,861)
Accounts payable and accrued liabilities	53	(467)	7,123	977
Lease payments recognized (deferred)			115	(40)
Operating lease right-of-use assets and liabilities, net	(7)	(21)
Net cash used in operating activities	(16,871)	(9,006)	(39,143)	(24,251)
Investing activities:
Purchases of property and equipment	(31)	(41)	(352)	(227)
Net cash used in investing activities	(31)	(41)	(352)	(227)
Financing Activities:
Proceeds from the issuance of Series B and Series C convertible preferred units, net	14,228	0	81,876	9,456
Issuance of common stock under VIE equity incentive plan			0	16
Deferred financing costs	(754)	0	(46)	0
Net cash provided by financing activities	13,474	0	81,830	9,472
Decrease in cash, cash equivalents and restricted cash	(3,428)	(9,047)	42,335	(15,006)
Cash, cash equivalents and restricted cash at beginning of year	67,489	25,154	25,154	40,160
Cash, cash equivalents and restricted cash at end of year	64,061	16,107	67,489	25,154
Supplemental disclosure of cash flow information:
Income taxes paid			15	4
Supplemental disclosure of non-cash investing and financing activities:
Amounts accrued for purchases of property and equipment	25	7	0	10
Right-of-use assets obtained in exchange for operating lease liabilities	0	1,369	1,412	0
Costs incurred in connection with initial public offering included in accounts payable and accrued expenses	1,930	0	795	0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	63,650	16,107	67,246	25,154
Restricted cash, non-current	411	0	243	0
Cash, cash equivalents and restricted cash at end of year	$ 64,061	$ 16,107	$ 67,489	$ 25,154

Organization and Business

Organization and Business	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Organization Consolidation And Presentation Of Financial Statements Abstract
Organization and Business	1. Organization and Business Organization 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 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 incentive 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. Zentalis Pharmaceuticals, LLC is a Delaware limited liability company. 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. 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. Liquidity Substantial doubt about an entity’s ability to continue as a going concern exists when relevant conditions and events, considered in the aggregate, indicate that it is probable that the entity will be unable to meet its obligations as they become due within one year from the financial statement issuance date. The Company determined that there are no conditions or events that raise substantial doubt about its ability to continue as a going concern within one year after the date that the interim unaudited condensed consolidated financial statements for the quarter ended March 31, 2020 are issued.	1. Organization and Business Organization 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 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 in exchange for Class B common incentive units in Zeno, 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 Zentalis Pharmaceuticals, LLC is a is a Delaware limited liability company. 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. Liquidity The accompanying financial statements have been prepared assuming that we will continue as a going concern. Management evaluates whether there are relevant conditions and events that in aggregate raise substantial doubt about our ability to continue as a going concern and to meet our obligations as they become due within one year from the date the financial statements are issued. We are subject to risk and uncertainties common to early-stage biotechnology companies including, but not limited to significant competition from therapies in development by other companies or already approved for sale by the U.S. Food and Drug Administration, protection of intellectual property, dependence on key personnel and compliance with government regulations. Management has prepared cash flow forecasts which indicate that there is not substantial doubt about our ability to continue as a going concern for the twelve months after the date the financial statements for the year ended December 31, 2019 are issued. We expect to incur substantial operating losses to continue development of drug candidates, including preclinical and clinical testing and regulatory approval prior to commercialization. Even if our drug development efforts are successful, it is uncertain when, if ever, we will realize significant revenue from product sales.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. 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. year-end 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. 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 Comprehensive Loss Comprehensive loss is equal to net loss for the periods ended March 31, 2020 and 2019. 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, 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, 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 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, 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.	2. Summary of Significant Accounting Policies Basis of Presentation The consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“U.S. GAAP”) and include 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. We evaluate our ownership, contractual and other interests in entities that are not wholly-owned to determine if these entities are VIEs, and, if so, whether we are the primary beneficiary of the VIE. In determining whether we are the primary beneficiary of a VIE and therefore required to consolidate the VIE, we apply a qualitative approach that determines whether we have both (1) the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and (2) the obligation to absorb losses of, or the rights to receive benefits from, the VIE that could potentially be significant to that VIE. On December 21, 2017, the Company acquired a 25% equity interest in Kalyra. Based on our assessment, we concluded that Kalyra is a variable interest entity and we are the primary beneficiary. Prior to the acquisition, Zeno 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 the Company’s consolidated financial statements from December 21, 2017, the date we became the primary beneficiary. The liabilities recognized as a result of consolidating Kalyra do not represent additional claims on the Company’s general assets. We will continuously assess whether we are the primary beneficiary of a VIE, as changes to existing relationships or future transactions may result in the consolidation or deconsolidation of such VIE. During the periods presented, we have not provided any other financial or other support to our VIE that we were not contractually required to provide. Noncontrolling Interests Noncontrolling interests represent the portion of equity (net assets) in Kalyra, our consolidated but not wholly-owned entity, that is neither directly nor indirectly attributable to us. 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. Cash and Cash Equivalents Cash equivalents are comprised of short-term, highly-liquid investments with maturities of 90 days or less at the date of purchase. As of December 31, 2018 and 2019, our cash equivalents consisted of money market funds. Restricted Cash Under the terms of our office lease, we are required to maintain a letter of credit as a security deposit during the term of such lease. At December 31, 2019, restricted cash of $0.2 million was pledged as collateral for the letter of credit. We were not required to maintain a letter of credit as a security deposit as of December 31, 2018. Fair Value of Financial Instruments The authoritative guidance defines fair value and requires us to establish a framework for measuring fair value and disclosure about fair value measurements using a three-tier approach. These tiers include: Level 1, defined as observable inputs such as quoted prices in active markets; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. Our financial instruments include cash equivalents, accounts receivable, prepaid expenses and other assets, accounts payable and accrued expenses. Fair value estimates of these instruments are made at a specific point in time, based on relevant market information. These estimates may be subjective in nature and involve uncertainties and matters of significant judgement and therefore cannot be determined with precision. The carrying amount of cash equivalents, account receivable, prepaid expenses and other assets, accounts payable and accrued expenses are generally considered to be representative of their respective values because of the short-term Concentrations of Credit Risk, Sources of Supply and Significant Customers We are subject to credit risk from our portfolio of cash equivalents. We maintain our cash and cash equivalent balances with two major commercial banks. Deposits held with the financial institutions exceed the amount of insurance provided on such deposits. We are exposed to credit risk in the event of a default by the financial institutions holding our cash and cash equivalents to the extent recorded on the consolidated balance sheets. We are also subject to credit risk from our accounts receivable related to our revenues under our license and collaboration agreement and reimbursements under our government grants. We have a license and collaboration agreement under which we receive payments for license fees, milestone payments and reimbursements of research and development services. Management monitors our exposure to accounts receivable by periodically evaluating the collectability of the accounts receivable based on a variety of factors including the length of time the receivables are past due, the financial health of the customer and historical experience. Based upon the review of these factors, we recorded no allowance for doubtful accounts at December 31, 2018 and 2019. As of December 31, 2018 and 2019, all of the outstanding accounts receivables are due from government entities. We rely on third-party manufacturers for the supply of active pharmaceutical ingredients. Accounts Receivable, Net Accounts receivable is recorded at the invoiced amount and is non-interest Property and Equipment, Net Property and equipment are recorded at cost, less accumulated depreciation and amortization. Equipment is depreciated using the straight-line method over its estimated useful life ranging from three to five years and leasehold improvements are amortized using the straight-line method over the estimated useful life of the asset or the lease term, whichever is shorter. Repair and maintenance costs are expensed as incurred. Leases We have entered into operating leases for real estate. We determine if an arrangement is a lease at inception and evaluate each lease agreement to determine whether the lease is an operating or finance lease. For leases where we are the lessee, right-of-use non-lease Impairment of Long-Lived Assets We account for long-lived assets in accordance with authoritative guidance for impairment or disposal of long-lived assets. Long-lived assets are reviewed for events or changes in circumstances, which indicate that their carrying value may not be recoverable. To date, we have not experienced any significant impairment losses. Goodwill and In-Process Our goodwill, which has an indefinite useful life, represents the excess of the cost over the fair value of net assets acquired from its business combination. The determination of the value of goodwill and intangible assets arising from business combinations and asset acquisitions requires extensive use of accounting estimates and judgments to allocate the purchase price to the fair value of the net tangible and intangible assets acquired, including capitalized in-process Intangible assets acquired in a business combination that are used for IPR&D activities are considered indefinite lived until the completion or abandonment of the associated research and development efforts. Upon conclusion of the relevant research and development project, we will amortize the acquired IPR&D over its estimated useful life or expense the acquired IPR&D should the research and development project be unsuccessful with no future alternative use. We base the useful lives and related amortization expense on our estimate of the period that the assets will generate revenues or otherwise be used. We assess the carrying value of our IPR&D assets at least annually, or more frequently if an event occurs indicating the potential for impairment, which requires us to make assumptions and judgements regarding the future cash flows of these assets. If the assets are considered to be impaired, the impairment we recognize is the amount by which the carrying value of the assets exceeds the fair value of the assets. Fair value is determined by a combination of third-party sources and forecasted discounted cash flows. Goodwill is reviewed for impairment at least annually, or more frequently if an event occurs indicating the potential for impairment. During the impairment review process, we consider qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit is less than the carrying amount, including goodwill. If we determine that it is not more likely than not that the fair value of our reporting unit is less than the carrying amount, then no additional assessment is deemed necessary. Otherwise, we perform the two-step Revenue Recognition In May 2014, the Financial Accounting Standards Board (“FASB”) issued accounting guidance on the recognition of revenue from customers. This guidance supersedes the revenue recognition requirements we previously followed in Accounting Standards Codification, or ASC, Topic 605, Revenue Recognition Revenue from Contracts with Customers, We generate revenues from payments received under a collaboration arrangement which included payments for nonrefundable fees at the inception of the agreement, license fees, milestone-based payments and reimbursements for research and development efforts. As of January 1, 2018, we adopted ASC 606, Revenue from Contracts with Customers Prior to the ASC 606 adoption, revenue was recognized when all the following criteria were met; (i) persuasive evidence of an arrangement exists; (ii) delivery has occurred or services have been rendered; (iii) the seller’s price to the buyer is fixed or determinable; and (iv) collectability is reasonably assured. Under the previous guidance, we recognized the upfront payment received from our collaborative partner on a straight- line basis over the performance period arrangement or from receipt until May 2036. There were no other adoption differences in revenue recognized due to the transition from the previously applied authoritative accounting literature to ASC 606. Upon the adoption of ASC 606, we concluded that all services had been rendered over the research period and recognized an adjustment to decrease deferred revenues and accumulated deficit by approximately $0.9 million. The impact of applying the provisions of ASC 606 in the year ended December 31, 2018 was to decrease revenues by forty-six Revenue under Collaborative Agreements We entered into a collaboration and license agreement (“the agreement”) with a specialty pharmaceutical company for the development and commercialization of products and product candidates for the treatment of various diseases and conditions relating to the field of oncology. Pursuant to the terms of the original agreement and related amendment, the collaborator made an upfront non-refundable Our collaboration partner can select additional compounds to add to the licenses granted. We consider these rights to be options without material rights, as these rights require additional fees and future royalties which do not represent discounts to similar licenses to a new collaboration partner. We consider grants of additional licenses upon exercises to be separate contracts. Under the collaboration agreement, we have identified a pre-clinical co-development The transaction price is the amount of consideration to which we expect to be entitled for transferring promised goods or services. The transaction price does not include amounts subject to uncertainties unless it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated to the amount is resolved. Upfront fees are contractually obligated and included in the transaction price. Consideration we may have received in exchange for milestones achieved were subject to significant uncertainties inherent in product development and were not included in the transaction price until deemed probable that the amount would not result in a significant reversal of revenue in the future. At the conclusion of each reporting period, we reassessed the probability of milestone achievement and expected payments for research and development services, and if necessary, adjusted our total estimated transaction price. As our collaboration agreement had one distinct bundle of performance obligations comprised of services and licenses delivered concurrently and were not subject to the right of return, allocation of the transaction price was not required. Upfront amounts allocated to licenses and ongoing services were recognized as revenue commencing upon transfer of the licenses over the research period of the target on a percentage of total costs to be incurred basis. We completed our ongoing services under the collaboration agreement during the fourth quarter of 2017 and therefore considered our performance obligations to have been fully satisfied at that time. Development milestones are recognized as revenue when the consideration is included in the transaction price over the remaining term of the research period. Royalties will be recognized when the underlying sales occur based on estimates. We will record a true-up We provide standard indemnification and protection of licensed intellectual property for our customers. These provisions are part of assurance that the licenses meet the agreement’s representations and are not an obligation to provide goods or services. Research and Development Expenses Research and development expenses include salaries and benefits, facilities and other overhead expenses, external clinical trial expenses, research related manufacturing services, contract services and other outside expenses. Research and development expenses are charged to operating expenses as incurred when these expenditures relate to our research and development efforts and have no alternative future uses. Reimbursed research and development costs under government grant arrangements are recorded as a reduction to research and development expenses and are recognized in the period in which the related costs are incurred. We are obligated to make upfront payments upon execution of certain research and development agreements. Advance payments, including nonrefundable amounts, for goods or services that will be used or rendered for future research and development activities are deferred. Such amounts are recognized as expense as the related goods are delivered or the related services are performed, or such time when we do not expect the goods to be delivered or services to be performed. Clinical Trial Expenses We make payments in connection with our clinical trials under contracts with contract research organizations that support conducting and managing clinical trials. The financial terms of these agreements are subject to negotiation and vary from contract to contract and may result in uneven payment flows. Generally, these agreements set forth the scope of work to be performed at a fixed fee, unit price or on a time and materials basis. A portion of our obligation to make payments under these contracts depends on factors such as the successful enrollment or treatment of patients or the completion of other clinical trial milestones. Expenses related to clinical trials are accrued based on our estimates and/or representations from service providers regarding work performed, including actual level of patient enrollment, completion of patient studies and progress of the clinical trials. Other incidental costs related to patient enrollment or treatment are accrued when reasonably certain. If the amounts we are obligated to pay under our clinical trial agreements are modified (for instance, as a result of changes in the clinical trial protocol or scope of work to be performed), we adjust our accruals accordingly. Revisions to our contractual payment obligations are charged to expense in the period in which the facts that give rise to the revision become reasonably certain. Share-Based Compensation We record share-based compensation expense associated with equity instruments in accordance with the authoritative guidance for stock-based compensation. The cost of employee services received in exchange for an award of an equity instrument is measured at the grant date based on the estimated fair value of the award and is recognized as expense on a straight-line basis over the requisite service period of the award. Share-based compensation expense for an award with a performance condition is recognized when the achievement of such performance condition is determined to be probable. If the outcome of such performance condition is not determined to be probable or is not met, no compensation expense is recognized, and any previously recognized compensation expense is reversed. Forfeitures are recognized as a reduction of share-based compensation expense as they occur. Income Taxes Deferred income taxes are recognized for the tax consequences in future years of differences between the tax basis of assets and liabilities and their financial reporting amounts at each year end based on enacted tax laws and statutory tax rates applicable to the periods in which the differences are expected to affect taxable income. A provision has been made for income taxes due on taxable income and for the deferred taxes on temporary differences. Deferred tax assets and liabilities are adjusted for the effects of changes in tax laws and rates on the date of enactment. Realization of the deferred income tax asset is dependent on gathering sufficient taxable income in future years. Valuation allowances are established when necessary to reduce deferred tax assets to the amount expected to be realized. Income tax expense is the combination of the tax payable for the period and the change during the period in deferred tax assets and liabilities. We follow the accounting guidance on accounting for uncertainty in income taxes. The guidance prescribes a recognition threshold and measurement attribute criteria for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities based on the technical merits of the position. Comprehensive Loss Comprehensive loss is equal to net loss for the years ended December 31, 2018 and 2019. Net Loss per Class A Common Unit Basic net loss per Class A common unit is computed by dividing net loss, after adjusting for preferred unit dividends, if declared by the weighted-average number of Class A common units outstanding during the period. Diluted net loss per common unit is computed using the weighted-average number of Class A common units outstanding during the period and, if dilutive the weighted average number of potential shares of Class A common units. The effect of the conversion of preferred units into Class A common units is excluded from the computation of diluted net loss per common unit for the period as their effect is antidilutive. Additionally, Class A common unit equivalents are excluded from the computation of diluted net loss per common unit for all periods as their effect is antidilutive. Adoption and Pending Adoption of Recent Accounting Pronouncements The following table provides a brief description of recently issued accounting standards, those adopted in the current period and those not yet adopted: Standard Description Effective Date Effect on the Financial In January 2016, the FASB issued ASU 2016-01, The new guidance supersedes the guidance to classify equity securities with readily determinable fair values into different categories (that is, trading or available-for-sale) January 1, 2018 We currently do not hold equity securities and therefore the adoption did not have a material impact on our consolidated financial position or results of operations. In May 2014, the FASB issued ASU 2014-09, The new standard will supersede nearly all existing revenue recognition guidance. Under Topic 606, an entity is required to recognize revenue upon transfer of promised goods or services to customers in an amount that reflects the expected consideration to be received in exchange for those goods or services. Topic 606 defines a five-step process in order to achieve this core principle, which may require the use of judgment and estimates, and also requires expanded qualitative and quantitative disclosures relating to the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers, including significant judgments and estimates used. The new standard also defines accounting for certain costs related to origination and fulfillment of contracts with customers, including whether such costs should be capitalized. The new standard permits adoption either by using (i) a full retrospective approach for all periods presented in the period of adoption or (ii) a modified retrospective approach where the new standard is applied in the financial statements starting with the year January 1, 2019 We have adopted the new guidance on January 1, 2018 using the modified retrospective approach. Refer to Note 2 “Revenue Recognition” for additional detail regarding the impact of the adoption. of adoption. Under both approaches, cumulative impact of the adoption is reflected as an adjustment to retained earnings (accumulated equity (deficit)) as of the earliest date presented in accordance with the new standard. In June 2018, the FASB issued ASU 2018-07, The FASB issued the new guidance as part of its ongoing Simplification Initiative. The ASU supersedes Subtopic 505-50 January 1, 2019 We have adopted the new guidance on January 1, 2018. The impact of the adoption was not material to the consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, This guidance revises the accounting related to leases by requiring lessees to recognize a lease liability and a right-of-use January 1, 2019 We have adopted Topic 842 on January 1, 2019 using a modified retrospective transition basis for leases existing as of the period of adoption. We implemented new processes and used the available practical expedients to implement the guidance. The practical expedients allowed us to carry forward our historical assessment of whether existing agreements are or contain a lease and the classification of our existing lease arrangements. All of our real-estate operating lease commitments are recognized as lease liabilities with corresponding right-of-use and liabilities of the consolidated balance sheet of $1.5 million, using an assumed weighted average discount rate of 11.0%. The adoption did not have an impact on our consolidated statements of operations and did not require recognition of a cumulative-effect adjustment to the opening balance of accumulated deficit in the period of adoption. We elected to continue applying the guidance under ASU 840, Leases for comparative periods, as allowed through ASU 2018-11, In June 2016, the FASB issued ASU 2016-13, 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 do not believe the adoption will have a material impact on our consolidated financial position or results of operations. 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, 2021 We do not believe the adoption will have a material impact on our consolidated financial position or results of operations.

Business Combinations

Business Combinations	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Business Combinations [Abstract]
Business Combinations	3. 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, Zeno 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 March 31, 2020 and December 31, 2019 are as follows (in thousands): March 31, December 31, 2020 2019 Cash and cash equivalents $ 286 $ 712 Other current assets 77 21 In-process research 8,800 8,800 Goodwill 3,736 3,736 Other long-term assets — 14 Accounts payable and accrued expenses 113 391 Deferred tax liability 2,463 2,463 Noncontrolling interests $ 6,712 $ 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 Zeno 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): March 31, March 31, 2020 2019 Noncontrolling interest at beginning of period $ 6,821 $ 7,536 Net loss attributable to noncontrolling interest (109 ) (320 ) Noncontrolling interest at end of period $ 6,712 $ 7,216	3. Business Combinations Kalyra Pharmaceuticals, Inc. On December 21, 2017, we acquired $4.5 million of Kalyra Pharmaceuticals, Inc.’s Series B Preferred Stock representing a 25% equity interest in Kalyra Pharmaceuticals, Inc. 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, Zeno 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 December 31, 2018 and 2019 are as follows (in thousands): December 31, 2018 2019 Cash and cash equivalents $ 1,482 $ 712 Other current assets 933 21 In-process 8,800 8,800 Goodwill 3,736 3,736 Other long-term assets 48 14 Accounts payable and accrued expenses 1,224 391 Deferred tax liability 2,463 2,463 Noncontrolling interests $ 7,536 $ 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 Zeno 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): December 31, 2018 2019 Noncontrolling interest at beginning of period $ 9,885 $ 7,536 Net loss attributable to noncontrolling interest (2,365 ) (715 ) Issuance of VIE shares under equity incentive plan 16 — Noncontrolling interest at end of period $ 7,536 $ 6,821

Fair Value Measurement

Fair Value Measurement	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurement	4. Fair Value Measurement As of March 31, 2020 and December 31, 2019, we held approximately $60.3 million and $63.0 million of money market funds measured at fair value on a recurring basis and categorized as Level 1 securities using the fair value hierarchy. There were no transfers between Level 1 and Level 2 of the fair value hierarchy during the three months ended March 31, 2020. We had no instruments that were classified within Level 3 as of March 31, 2020 or December 31, 2019.	4. Fair Value Measurement As of December 31, 2018 and 2019, we held approximately $23.2 million and $63.0 million of money market funds measured at fair value on a recurring basis and categorized as Level 1 securities using the fair value hierarchy. There were no transfers between Level 1 and Level 2 of the fair value hierarchy during the years ended December 31, 2018 and 2019. We had no instruments that were classified within Level 3 as of December 31, 2018 and 2019.

Prepaid Expenses and Other Asse

Prepaid Expenses and Other Assets	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid Expenses and Other Assets	5. Prepaid Expenses and Other Assets Prepaid expenses and other assets consisted of the following (in thousands): March 31, December 31, 2020 2019 Prepaid insurance $ 303 $ 150 Prepaid software licenses and maintenance 299 238 Prepaid research and development expenses 3,668 2,985 Other prepaid expenses 303 266 Total prepaid expenses and other current assets 4,573 3,639 Less long-term portion 2,353 2,134 Total prepaid expenses and other assets, current $ 2,220 $ 1,505	5. Prepaid Expenses and Other Assets Prepaid expenses and other assets consisted of the following (in thousands): December 31, 2018 2019 Prepaid insurance $ 98 $ 150 Prepaid software licenses and maintenance 126 238 Prepaid research and development expenses 1,715 2,985 Prepaid rent and related security deposits 104 168 Other prepaid expenses 88 98 Total prepaid expenses and other current assets 2,131 3,639 Less long-term portion 1,525 2,134 Total prepaid expenses and other assets, current $ 606 $ 1,505

Property and Equipment, net

Property and Equipment, net	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Property and Equipment, net	6. Property and Equipment, net Property and equipment, net consisted of the following (in thousands): March 31, December 31, 2020 2019 Computer and Office Equipment $ 271 $ 243 Lab Equipment 401 401 Leasehold Improvements 24 24 Construction in Progress 28 — Subtotal 724 668 Accumulated depreciation and amortization (205 ) (167 ) Property and equipment, net $ 519 $ 501 Depreciation and amortization expense for the three months ended March 31, 2020 and 2019 was approximately thirty-eight thousand and twenty-one	6. Property and Equipment, net Property and equipment, net consisted of the following (in thousands): December 31, 2018 2019 Computer and Office Equipment $ 39 $ 243 Lab Equipment 277 401 Leasehold Improvements — 24 Subtotal 316 668 Accumulated depreciation and amortization (56 ) (167 ) Property and equipment, net $ 260 $ 501 Depreciation and amortization expense was approximately $0.1 million and $0.1 million for the years ended December 31, 2018 and 2019, respectively.

Accrued Expenses

Accrued Expenses	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Accrued Expenses	7. Accrued Expenses Accrued expenses consist of the following (in thousands): March 31, December 31, 2020 2019 Accrued research and development expenses $ 5,103 $ 5,465 Accrued employee expenses 2,008 2,977 Accrued general and administrative expenses 1,916 1,356 Lease liability 810 781 Other 83 29 Total accrued expenses $ 9,920 $ 10,608	7. Accrued Expenses Accrued expenses consist of the following (in thousands): December 31, 2018 2019 Accrued research and development expenses $ 1,137 $ 5,465 Accrued employee expenses 1,023 2,977 Accrued general and administrative expenses 356 1,356 Lease liability, current portion — 781 Other 38 29 Total accrued expenses $ 2,554 $ 10,608

Convertible Preferred Units

Convertible Preferred Units	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Equity [Abstract]
Convertible Preferred Units	8. 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. The authorized, issued, and outstanding shares of convertible preferred units at March 31, 2020 and December 31, 2019 were as follows: March 31, 2020 Series Units Shares Issued Liquidation Carrying Value Series A convertible preferred units 1,579,309 1,579,309 $ 18,319,984 $ 18,225,809 Series B convertible preferred units 3,523,739 3,523,739 43,800,076 41,603,945 Series C convertible preferred units 5,714,300 5,714,300 100,000,250 96,104,453 Total 10,817,348 10,817,348 $ 162,120,310 $ 155,934,207 December 31, 2019 Series Units Shares Issued Liquidation Carrying Value Series A convertible preferred units 1,579,309 1,579,309 $ 18,319,984 $ 18,225,809 Series B convertible preferred units 3,523,739 3,523,739 43,800,076 41,603,945 Series C convertible preferred units 5,714,300 4,847,106 84,824,355 81,876,092 Total 10,817,348 9,950,154 $ 146,944,415 $ 141,705,846 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 three months ended March 31, 2020, we did not adjust the carrying values of the convertible preferred units to the deemed redemption values of such units since a liquidation event was not probable. Dividends Dividends are payable if and when declared by the Board of Directors. No dividends have been declared through March 31, 2020. Conversion Each Series A preferred unit, Series B preferred unit and Series C preferred unit shall be 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 is $11.60, $12.43 and $17.50 per unit, respectively. The convertible preferred units will automatically convert at the then applicable conversion rate upon the closing of a firm commitment underwritten public offering of shares of a successor corporations’ common stock, at a public offering price per share of equal to or greater than the Series C original purchase price (as adjusted for any stock splits, stock dividends, combinations or other similar recapitalization) resulting in aggregate gross cash proceeds of at least $75.0 million (a “Qualified IPO”). Additionally, the convertible preferred unit will be 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). Anti-dilution protection The holders of the convertible preferred unit have 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, shall be on a broad-based weighted average basis. Protective rights The holders of the convertible preferred unit have 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 must 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), Redemption The Series A, Series B and Series C convertible preferred units are not redeemable except in the event of certain effected deemed liquidation events. As of March 31, 2020 and December 31, 2019, we have 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 are 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 are entitled to receive, on a pro rata basis in respect of each convertible preferred unit in proportion to the relative preference amount of each preferred unit, a preference amount of $11.60 and $12.43 per unit of Series A and Series B convertible preferred units (as adjusted for any units splits, dividend, combinations, recapitalizations of the like), respectively. Subsequent to the payment of the Series C, Series A and Series B convertible preferred unit preferences, Series A, Series B and Series C convertible preferred units are entitled to receive, on an as converted to common unit pro rata basis, an amount equal to distributions made to Class A common units prior to all unit classes sharing in distributions on a pro rata basis. Thereafter, Series A, Series B and Series C convertible preferred units and Series A and Series B common units are 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 are unvested shall vote together as a single class. Each holder of Series A, Series B and Series C convertible preferred units shall be entitled to the number of votes calculated on an as converted to Class A common unit basis.	8. 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 (see note 9). 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. The authorized, issued, and outstanding shares of convertible preferred units at December 31, 2018 and 2019 were as follows: December 31, 2018 Series Units Shares Issued Liquidation Carrying Value Series A convertible preferred units 1,638,000 1,579,309 $ 18,319,984 $ 18,225,809 Series B convertible preferred units 3,621,000 3,523,739 43,800,076 41,603,945 Total 5,259,000 5,103,048 $ 62,120,060 $ 59,829,754 December 31, 2019 Series Units Shares Issued Liquidation Carrying Value Series A convertible preferred units 1,579,309 1,579,309 $ 18,319,984 $ 18,225,809 Series B convertible preferred units 3,523,739 3,523,739 43,800,076 41,603,945 Series C convertible preferred units 5,714,300 4,847,106 84,824,355 81,876,092 Total 10,817,348 9,950,154 $ 146,944,415 $ 141,705,846 At December 31, 2018, the convertible preferred units were classified in members’ equity. During 2019, we reclassified the convertible preferred units 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, 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. Subsequent adjustments to increase the carrying values to the ultimate redemption values will be made only when it becomes probable that such a liquidation event will occur. Dividends Dividends are payable if and when declared by the Board of Directors. No dividends were declared during the years ended December 31, 2018 and 2019. Conversion Each Series A preferred unit, Series B preferred unit and Series C preferred unit shall be 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 is $11.60, $12.43 and $17.50 per unit, respectively. The convertible preferred units will automatically convert at the then applicable conversion rate upon the closing of a firm commitment underwritten public offering of shares of a successor corporations’ common stock, at a public offering price per share of equal to or greater than the Series C original purchase price (as adjusted for any stock splits, stock dividends, combinations or other similar recapitalization) resulting in aggregate gross cash proceeds of at least $75.0 million (a “Qualified IPO”). Additionally, the convertible preferred unit will be 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). Anti-dilution protection The holders of the convertible preferred unit have 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, shall be on a broad-based weighted average basis. Protective rights The holders of the convertible preferred unit have 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 must 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 Redemption The Series A, Series B and Series C convertible preferred units are not redeemable except in the event of certain effected deemed liquidation events. As of December 31, 2019, we have 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 are 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 are entitled to receive, on a pro rata basis in respect of each convertible preferred unit in proportion to the relative preference amount of each preferred unit, a preference amount of $11.60 and $12.43 per unit of Series A and Series B convertible preferred units (as adjusted for any units splits, dividend, combinations, recapitalizations of the like), respectively. Subsequent to the payment of the Series C, Series A and Series B convertible preferred unit preferences, Series A, Series B and Series C convertible preferred units are entitled to receive, on an as converted to common unit pro rata basis, an amount equal to distributions made to Class A common units prior to all unit classes sharing in distributions on a pro rata basis. Thereafter, Series A, Series B and Series C convertible preferred units and Series A and Series B common units are 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 are unvested shall vote together as a single class. Each holder of Series A, Series B and Series C convertible preferred units shall be entitled to the number of votes calculated on an as converted to Class A common unit basis.

Members' Equity

Members' Equity	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Equity [Abstract]
Members' Equity	9. Members’ Equity In November 2017, Zentalis Pharmaceuticals, LLC was formed in the state of Delaware. In conjunction with a corporate restructuring, Zeno Pharmaceuticals, Inc., a Delaware Corporation formed in 2014, was acquired by the Company pursuant to a merger agreement and became a wholly owned subsidiary of the Company. Per the terms of the merger agreement, each share of Zeno Pharmaceuticals, Inc. common stock issued and outstanding immediately prior to the effective time of the merger was converted into the right to receive one Class A common unit and each share of Zeno Pharmaceuticals, Inc. Series A preferred stock issued and outstanding immediately prior to the effective date of the merger converted into the right to receive one Series A preferred unit. As of the effective time of the merger agreement, all outstanding options to purchase shares of Zeno Pharmaceuticals, Inc. common stock were cancelled and replaced with 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 March 31, 2020 and 2019, we did not issue any Class A common units and 9,572 shares of Class A common units were subject to future vesting conditions. During the year ended December 31, 2019, 7,093 Class A common units were issued and 9,572 shares of 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. Share-based Compensation Total share-based compensation expense related to share based awards was comprised of the following (in thousands): Three Months Ended 2020 2019 Research and development expense $ 136 $ 66 General and administrative expense 193 63 Total share-based compensation expense $ 329 $ 129 As of March 31, 2020, there was $3.4 million of total unrecognized compensation expense related to unvested profit interest award compensation arrangements granted under the Zeno Pharma, LLC 2017 Profit Interest Plan (the “Plan”). The cost is expected to be recognized over a weighted average period of 3.2 years. The fair value of the profit interest awards is estimated using an option pricing model with the following assumptions: Three Months Ended March 31, 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 1.3 Lack of marketability discount 26.5 % 1.9 % Grant date fair value $ 3.06 $ 1.88 The Black Scholes option pricing model is used to estimate the fair value of each profit 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 apply the risk-free interest rate based on the U.S. Treasury yield in effect at the time of the grant consistent with the life of the award. The expected volatility is based on a peer group in the industry in which the Company does business consistent with the expected time to liquidity. The dividend yield was set at zero as the underlying security does not and is not expected to pay a dividend. The Finnerty model and the Asian Protective Put Model methods were used to estimate the discount for lack of marketability inherent to the awards. The Class B common units issued have been classified as equity awards and share-based compensation expense is based on the grant date fair value of the award. During the three months ended March 31, 2020 and 2019, we issued 70,000 and 47,500 Class B common units, respectively. As of March 31, 2020 and December 31, 2019, approximately 1.5 million units and 1.7 million units of unvested Class B common units were outstanding.	9. Members’ Equity In November 2017, Zentalis Pharmaceuticals, LLC was formed in the state of Delaware. In conjunction with a corporate restructuring, Zeno Pharmaceuticals, Inc., a Delaware Corporation formed in 2014, was acquired by the Company pursuant to a merger agreement and became a wholly owned subsidiary of the Company. Per the terms of the merger agreement, each share of Zeno Pharmaceuticals, Inc. common stock issued and outstanding immediately prior to the effective time of the merger was converted into the right to receive one Class A common unit and each share of Zeno Pharmaceuticals, Inc. Series A preferred stock issued and outstanding immediately prior to the effective date of the merger converted into the right to receive one Series A preferred unit. As of the effective time of the merger agreement, all outstanding options to purchase shares of Zeno Pharmaceuticals, Inc. common stock were cancelled and replaced with 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 years ended December 31, 2018 and 2019, zero and 7,093 Class A common units were issued. As of December 2018 and 2019, 24,236 and 9,572 shares of Class A common units were subject to future vesting conditions, respectively. 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. Equity Awards The Zentalis Pharmaceuticals, LLC Profit Interest Plan We currently grant profit interest awards to employees, consultants and non-employee non-voting The fair value of the profit interest awards is estimated using an option pricing model with the following assumptions: Year ended December 31, 2018 2019 Members’ equity value (in thousands) $ 113,100 $ 197,041 - $271,207 Threshold amounts (in thousands) $ 134,000 - $143,800 $ 143,800 - $309,824 Risk free rate 2.8 % 1.5 % Volatility 75.0 % 75.0 % Time to liquidity (in years) 1.3 1.1 - 1.8 Lack of marketability discount 25.0 % 18.8% - 26 .4% Grant date fair value $ 1.85 - $2.01 $ 1.88 - $3.06 The Black Scholes option pricing model is used to estimate the fair value of each profit 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 apply the risk-free interest rate based on the U.S. Treasury yield in effect at the time of the grant consistent with the life of the award. The expected volatility is based on a peer group in the industry in which the Company does business consistent with the expected time to liquidity. The dividend yield was set at zero as the underlying security does not and is not expected to pay a dividend. The Finnerty model and the Asian Protective Put Model methods were used to estimate the discount for lack of marketability inherent to the awards. The Class B common units issued have been classified as equity awards and share-based compensation expense is based on the grant date fair value of the award. The following table provides a summary of the Class B common unit activity under the Plan. The amounts include incentive units granted to both employees and non-employees: Number of Units Weighted Average Fair Value Outstanding at December 31, 2017 703,000 $ 1.47 Granted 947,166 $ 1.62 Forfeited (37,855 ) $ 1.47 Outstanding at December 31, 2018 1,612,311 $ 1.56 Granted 1,095,545 $ 2.73 Forfeited (37,188 ) $ 1.62 Outstanding at December 31, 2019 2,670,668 $ 2.04 At December 31, 2019, there are 1,008,479 and 1,662,189 Class B common units vested and unvested, respectively, and 787,854 Class B common units were available for future grants. During 2018 and 2019, the share-based compensation expense included in the statement of operations was as follows: Year ended 2018 2019 Research and development expense $ 158 $ 339 General and administrative expense 150 278 Total share-based compensation expense $ 308 $ 617 As of December 31, 2019, there was $3.8 million of total unrecognized compensation expense related to unvested profit interest award compensation arrangements granted under the Plan. The cost is expected to be recognized over a weighted average period of 3.4 years.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. 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 March 31, 2020 are as follows (in thousands): Year Operating 2020 $ 765 2021 1,044 2022 661 2023 187 Total minimum lease payments: 2,657 Less: imputed interest (363 ) Total operating lease liabilities 2,294 The weighted-average remaining lease term of our operating leases is approximately 2.7 years. As of March 31, 2020, we have entered an additional lease for real estate that has not yet commenced with total minimum lease payments of approximately $23.1 million. This lease is expected to commence in the first quarter of 2021 and has a lease term of 10 years.	10. Commitments and Contingencies Operating Leases We entered into a non-cancellable In April 2019, we entered into a lease for approximately 4,800 square feet of office space in New York, New York. The lease commenced in May 2019 and continues through June 30, 2023. The lease is subject to approximately 3.0% annual increases throughout the term of the lease. We received lease incentives under the agreement, including tenant allowances and a free rent period. We also pay for various operating costs, including utilities and real property taxes. The agreement does not contain a renewal option but does contain an early termination provision. In August 2019, we entered into a sublease for approximately 2,333 square feet of office space adjacent to the existing laboratory and office space in San Diego, California. The lease commenced in October 2019 and continues through February 2022. The lease is subject to approximately 3% annual increases throughout the term of the lease. We also pay for various operating costs, including utilities and real property taxes. The agreement does not contain a renewal option or an early termination provision. Rent expense recorded by the Company under the leases was approximately $0.8 million and $0.4 million for the years ended December 31, 2019 and 2018, respectively. The following table presents the weighted average remaining lease term and weighted average discount rates related to our operating leases as of December 31, 2019: Cash paid in 2019 related to operating leases (in thousands) $ 700 Weighted average remaining lease term (in years) 2.9 Weighted average discount rate 11.0 % Approximate annual future minimum operating lease payments as of December 31, 2019 are as follows (in thousands): Year-ending December 31, Payment Amount 2020 $ 1,015 2021 1,044 2022 661 2023 187 Total minimum lease payments: 2,907 Less: imputed interest (431 ) Total operating lease liabilities 2,476 Less: current portion 781 Lease liability, net of current portion $ 1,695 As of December 31, 2018, prior to the adoption of ASU 2016-02, As of December 31, 2019, we have had no additional significant operating or finance leases that had not yet commenced.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	11. Income Taxes Zentalis Pharmaceuticals, LLC is treated as a partnership for tax purposes, and thus, not subject to income taxes. It is the responsibility of the LLC members to report their proportion share of any taxable income or loss generated by Zentalis Pharmaceuticals, LLC to the appropriate taxing authorities and pay the associated taxes, if any. With respect to our consolidated subsidiaries and variable interest entity, these entities are treated as corporations for tax purposes and are subject to income taxes which have been included in the consolidated financial statements. All pre-tax The following table presents the current and deferred income tax provision (benefit) for federal and state income taxes (in thousands): 2018 2019 Current tax provision: Federal $ — $ — State 4 15 Total current tax provision 4 15 Deferred tax provision: Federal — — State — — Total deferred tax provision — — Total provision for income taxes: $ 4 $ 15 A reconciliation of the expected tax computed at the U.S. statutory federal income tax rate to the total provision for income taxes at December 31 follows (in thousands): 2018 2019 Expected tax at 21% $ (4,921 ) 21.0 % $ (9,730 ) 21.0 % State income tax, net of federal tax (1,581 ) 6.8 % (3,167 ) 6.8 % Limited liability company loss 8 -0.1 % 4 -0.0 % Non-deductible 187 -0.8 % 164 -0.3 % Research credits (1,145 ) 4.9 % (1,424 ) 3.1 % Other 191 -0.8 % (2 ) 0.0 % Change in valuation allowance 7,265 -31.0 % 14,170 -30.6 % Provision for income taxes $ 4 0.0 % $ 15 0.0 % Deferred income taxes as of the following period reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of our net deferred tax asset or liability at December 31, 2018 and 2019 are as follows (in thousands): 2018 2019 Deferred tax assets Net operating loss $ 12,425 $ 25,053 Compensation 13 148 Deferred rent 5 — ASC 842 lease liability — 693 State tax 1 1 Research credits 2,079 3,503 Total gross deferred tax assets 14,523 29,398 Valuation allowance (14,477 ) (28,647 ) Net deferred tax assets 46 751 Deferred tax liabilities Depreciable assets (46 ) (97 ) ASC 842 right of use asset — (654 ) In-process (2,463 ) (2,463 ) Deferred tax liabilities (2,509 ) (3,214 ) Net deferred tax liabilities $ (2,463 ) $ (2,463 ) Realization of a portion of our deferred tax assets is dependent upon our generating sufficient taxable income in future years to obtain benefit from the reversal of temporary differences. Management considered all available evidence under existing tax law and anticipated expiration of tax statutes and determined that a valuation allowance of $28.6 million and $14.5 million was required as of December 31, 2019 and 2018, for those deferred tax assets that are not expected to provide future tax benefits. The acquisition of Kalyra (see footnotes 2 and 3) resulted in an allocation of the purchase price to In-process At December 31, 2018 and 2019, we have available net operating loss carryforwards of approximately $44.1 million and $89.2 million, respectively for the federal income tax purposes, of which $68.2 million were generated after 2017 and can be carried forward indefinitely under the Tax Cuts and Jobs Act. The remaining federal net operating loss of $21.0 million, which were generated prior to 2018, will start to expire in 2033 if not utilized. At December 31, 2018 and 2019, the net operating losses for state purposes are $45.4 million and $90.4 million, respectively and will begin to expire in 2033 if not utilized. At December 31, 2018, we have federal and state income tax credit carryforwards, net of reserves, of approximately $1.3 million and $0.9 million, respectively. At December 31, 2019, we have federal and state income tax credit carryforwards, net of reserves, of approximately $2.3 million and $1.4 million, respectively. The federal credit carryforwards begin to expire in 2033. The state credit carryforwards do not expire. We have not completed a study to determine whether an ownership change per the provisions of Section 382 of the Internal Revenue Code of 1986, as amended, as well as similar state provisions, has occurred. Utilization of our net operating loss and income tax credit carryforwards may be subject to a substantial annual limitation due to ownership changes that may have occurred or that could occur in the future. These ownership changes may limit the amount of the net operating loss and income tax credit carryover that can be utilized annually to offset future taxable income. In general, an “ownership change” as defined by Section 382 of the Code results from a transaction or series of transactions over a three-year period resulting in an ownership change of more than 50 percentage points of the outstanding stock of a company by certain stockholders. Uncertain Tax Positions In accordance with authoritative guidance, the impact of an uncertain income tax position on the income tax return must be recognized at the largest amount that is more-likely-than-not The following table reconciles the beginning and ending amount of unrecognized tax benefits for the year ended December 31, 2018 and 2019 (in thousands): 2018 2019 Gross unrecognized tax benefits at the beginning of the year $ 325 $ 741 Additions from tax positions taken in the current year 416 383 Gross unrecognized tax benefits at end of the year $ 741 $ 1,124 Of the total unrecognized tax benefits at December 31, 2018 and 2019, no amount will impact our effective tax rate due to the Company’s full valuation allowance. We do not anticipate that there will be a substantial change in unrecognized tax benefits within the next 12 months. We recognize interest and penalties related to unrecognized tax positions within the income tax expense line in the accompanying consolidated statements of operations. There were no accrued interest and penalties associated with uncertain tax positions as of December 31, 2018 or December 31, 2019. We and our subsidiaries are subject to U.S. federal and state income tax, and in the normal course of business, its income tax returns are subject to examination by the relevant taxing authorities. As of December 31, 2019, the 2016—2019 tax years remain subject to examination in the U.S. federal tax and various state tax jurisdictions. However, to the extent allowed by law, the taxing authorities may have the right to examine the period from 2013 through 2019 where net operating losses and income tax credits were generated and carried forward and make adjustments to the amount of the net operating loss and income tax credit carryforward amount. We are not currently under examination by federal or state jurisdictions.

Net Loss Per Class A Common Uni

Net Loss Per Class A Common Unit	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Net Loss Per Class A Common Unit	11. Net Loss Per Class A Common Unit Basic and diluted net loss per Class A common unit were calculated as follows (in thousands except per unit amounts): Three Months Ended 2020 2019 Numerator: Net loss attributable to Zentalis Pharmaceuticals, LLC $ (16,126 ) $ (8,343 ) Denominator: Weighted average number of Class A common units outstanding, basic and diluted 5,601 5,594 Net loss per Class A common unit $ (2.88 ) $ (1.49 ) Our potential and dilutive securities, which include preferred units, have been excluded from the computation of diluted net loss per Class A common unit as the effect would be to reduce the net loss per Class A common unit. 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 Class A common unit equivalents have been excluded from the calculations of diluted net loss per Class A common unit because their inclusion would be antidilutive (in thousands). Three Months Ended 2020 2019 Preferred units, as if converted to Class A common units 10,817 5,103 Incentive units—Class B common units 2,607 1,660 13,424 6,763	12. Net Loss Per Class A Common Unit Net Loss Per Class A Common Unit Basic and diluted net loss per Class A common unit were calculated as follows (in thousands except per share amounts): Year ended 2018 2019 Net loss attributable to Zentalis Pharmaceuticals, LLC $ (21,067 ) $ (45,663 ) Weighted average number of Class A common units outstanding, basic and diluted 5,594 5,597 Net loss per Class A common unit $ (3.77 ) $ (8.16 ) Our potential and dilutive securities, which include preferred units, have been excluded from the computation of diluted net loss per Class A common unit as the effect would be to reduce the net loss per Class A common unit. 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 Class A common unit equivalents have been excluded from the calculations of diluted net loss per Class A common unit because their inclusion would be antidilutive (in thousands). Year ended 2018 2019 Preferred units, as if converted to Class A common units 5,103 9,950 Incentive units—Class B common units 1,612 2,671 6,715 12,621 The unaudited pro forma basic and diluted weighted average common unit outstanding used in the calculation of unaudited pro forma basic and diluted net loss per unit attributable to common unit holders for the year ended December 31, 2019 has been prepared to give effect to the conversion of Zentalis Pharmaceuticals, LLC to a C-corporation, Year ended Net loss attributable to Zentalis Pharmaceuticals, LLC common units—basic and diluted $ (45,663 ) Weighted average number of common units outstanding 8,815 Pro forma adjustments to reflect automatic conversion of convertible preferred units to common stock upon the completion of the proposed initial public offering 9,237 Pro forma weighted average number of shares outstanding—basic and diluted 18,058 Pro forma net loss per common share $ (2.53 )

Employee Savings Plan

Employee Savings Plan	12 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
Employee Savings Plan	13. Employee Savings Plan We have an employee savings plan pursuant to Section 401(k) of the Internal Revenue Code. All employees are eligible to participate provided that they meet the requirements of the plan. The Company does not make matching contributions under the plan.

Related Party Disclosures

Related Party Disclosures	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Related Party Transactions [Abstract]
Related Party Disclosures	12. 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 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 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 The Master Services Agreement (“MSA”) was entered into in January 2015 and states that Kalyra may provide research and development services to us and that we shall reimburse such expenses on a time and materials basis based on the initial statements of work. For the three months ended March 31, 2020 and 2019, we incurred approximately seventeen thousand and five thousand dollars of expense with Kalyra that was eliminated in consolidation for research and development services provided, respectively. As of March 31, 2020 and 2019, approximately seventeen thousand and five thousand dollars was due to Kalyra and eliminated in consolidation. We entered into an Intercompany Services Agreement (“ISA”) with Kalyra in January 2018 which states that we may provide research and development services to Kalyra and that Kalyra shall reimburse such expenses on a time and materials basis. For the three months ended March 31, 2020 and 2019, we provided $0.1 million and $0.2 million of research and development services to Kalyra that was eliminated in consolidation, respectively. As of March 31, 2020 and 2019, $0.1 million and $0.8 million was due from Kalyra and eliminated in consolidation, respectively.	14. Related Party Disclosures On December 21, 2017, we acquired 17,307,692 shares of Series B preferred stock of Kalyra Pharmaceuticals, Inc. for a per share price of twenty-six 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 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 The Master Services Agreement (“MSA”) was entered into in January 2015 and states that Kalyra may provide research and development services to us and that we shall reimburse such expenses on a time and materials basis based on the initial statements of work. For the years ended December 31, 2018 and 2019, we incurred approximately $1.3 million and five thousand dollars of expense with Kalyra that was eliminated in consolidation for research and development services provided, respectively. As of December 31, 2018 and 2019, $1.2 million and seventeen thousand dollars was due to Kalyra and eliminated in consolidation. We entered into an Intercompany Services Agreement (“ISA”) with Kalyra in January 2018 which states that we may provide research and development services to Kalyra and that Kalyra shall reimburse such expenses on a time and materials basis. For the years ended December 31, 2018 and 2019, we provided $0.5 million and $0.7 million of research and development services to Kalyra that was eliminated in consolidation, respectively. As of December 31, 2018 and 2019, $0.5 million and $0.2 million was due from Kalyra and eliminated in consolidation, respectively.

Subsequent Events

Subsequent Events	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	13. Subsequent Events IPO 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.	15. Subsequent Events San Diego office expansion In January 2020, we entered a lease for approximately 36,955 square feet of office and laboratory space in San Diego, California. The targeted lease commencement date is January 2021 and will continue for 120 months thereafter. The lease is subject to approximately 3% annual increases throughout the term of the lease. We also pay for various operating costs, including utilities and real property taxes. The agreement contains extension rights allowing us to extend the term of the lease for five years at the then market rate. The agreement does not contain an early termination provision. The expected future minimum lease obligations under the agreement are as follows (in thousands): Year-ending December 31, Payment 2021 $ 2,018 2022 2,078 2023 2,140 2024 2,205 2025 2,271 Thereafter 12,419 Total minimum lease payments: $ 23,131 Series C Closing In February 2020, we issued 867,194 additional units of Series C preferred units under the Series C Preferred Unit Purchase Agreement (the “Series C 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. We have evaluated subsequent events through the report date.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Accounting	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. year-end	The consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (“U.S. GAAP”) and include 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. We evaluate our ownership, contractual and other interests in entities that are not wholly-owned to determine if these entities are VIEs, and, if so, whether we are the primary beneficiary of the VIE. In determining whether we are the primary beneficiary of a VIE and therefore required to consolidate the VIE, we apply a qualitative approach that determines whether we have both (1) the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and (2) the obligation to absorb losses of, or the rights to receive benefits from, the VIE that could potentially be significant to that VIE. On December 21, 2017, the Company acquired a 25% equity interest in Kalyra. Based on our assessment, we concluded that Kalyra is a variable interest entity and we are the primary beneficiary. Prior to the acquisition, Zeno 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 the Company’s consolidated financial statements from December 21, 2017, the date we became the primary beneficiary. The liabilities recognized as a result of consolidating Kalyra do not represent additional claims on the Company’s general assets. We will continuously assess whether we are the primary beneficiary of a VIE, as changes to existing relationships or future transactions may result in the consolidation or deconsolidation of such VIE. During the periods presented, we have not provided any other financial or other support to our VIE that we were not contractually required to provide.
Noncontrolling Interests		Noncontrolling Interests Noncontrolling interests represent the portion of equity (net assets) in Kalyra, our consolidated but not wholly-owned entity, that is neither directly nor indirectly attributable to us.
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	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.
Cash and Cash Equivalents		Cash and Cash Equivalents Cash equivalents are comprised of short-term, highly-liquid investments with maturities of 90 days or less at the date of purchase. As of December 31, 2018 and 2019, our cash equivalents consisted of money market funds.
Restricted Cash		Restricted Cash Under the terms of our office lease, we are required to maintain a letter of credit as a security deposit during the term of such lease. At December 31, 2019, restricted cash of $0.2 million was pledged as collateral for the letter of credit. We were not required to maintain a letter of credit as a security deposit as of December 31, 2018.
Fair Value of Financial Instruments		Fair Value of Financial Instruments The authoritative guidance defines fair value and requires us to establish a framework for measuring fair value and disclosure about fair value measurements using a three-tier approach. These tiers include: Level 1, defined as observable inputs such as quoted prices in active markets; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. Our financial instruments include cash equivalents, accounts receivable, prepaid expenses and other assets, accounts payable and accrued expenses. Fair value estimates of these instruments are made at a specific point in time, based on relevant market information. These estimates may be subjective in nature and involve uncertainties and matters of significant judgement and therefore cannot be determined with precision. The carrying amount of cash equivalents, account receivable, prepaid expenses and other assets, accounts payable and accrued expenses are generally considered to be representative of their respective values because of the short-term
Concentrations of Credit Risk, Sources of Supply and Significant Customers		Concentrations of Credit Risk, Sources of Supply and Significant Customers We are subject to credit risk from our portfolio of cash equivalents. We maintain our cash and cash equivalent balances with two major commercial banks. Deposits held with the financial institutions exceed the amount of insurance provided on such deposits. We are exposed to credit risk in the event of a default by the financial institutions holding our cash and cash equivalents to the extent recorded on the consolidated balance sheets. We are also subject to credit risk from our accounts receivable related to our revenues under our license and collaboration agreement and reimbursements under our government grants. We have a license and collaboration agreement under which we receive payments for license fees, milestone payments and reimbursements of research and development services. Management monitors our exposure to accounts receivable by periodically evaluating the collectability of the accounts receivable based on a variety of factors including the length of time the receivables are past due, the financial health of the customer and historical experience. Based upon the review of these factors, we recorded no allowance for doubtful accounts at December 31, 2018 and 2019. As of December 31, 2018 and 2019, all of the outstanding accounts receivables are due from government entities. We rely on third-party manufacturers for the supply of active pharmaceutical ingredients.
Accounts Receivable, Net		Accounts Receivable, Net Accounts receivable is recorded at the invoiced amount and is non-interest
Property and Equipment, Net		Property and Equipment, Net Property and equipment are recorded at cost, less accumulated depreciation and amortization. Equipment is depreciated using the straight-line method over its estimated useful life ranging from three to five years and leasehold improvements are amortized using the straight-line method over the estimated useful life of the asset or the lease term, whichever is shorter. Repair and maintenance costs are expensed as incurred.
Leases		Leases We have entered into operating leases for real estate. We determine if an arrangement is a lease at inception and evaluate each lease agreement to determine whether the lease is an operating or finance lease. For leases where we are the lessee, right-of-use non-lease
Impairment of Long-Lived Assets		Impairment of Long-Lived Assets We account for long-lived assets in accordance with authoritative guidance for impairment or disposal of long-lived assets. Long-lived assets are reviewed for events or changes in circumstances, which indicate that their carrying value may not be recoverable. To date, we have not experienced any significant impairment losses.
Goodwill and In-Process Research and Development		Goodwill and In-Process Our goodwill, which has an indefinite useful life, represents the excess of the cost over the fair value of net assets acquired from its business combination. The determination of the value of goodwill and intangible assets arising from business combinations and asset acquisitions requires extensive use of accounting estimates and judgments to allocate the purchase price to the fair value of the net tangible and intangible assets acquired, including capitalized in-process Intangible assets acquired in a business combination that are used for IPR&D activities are considered indefinite lived until the completion or abandonment of the associated research and development efforts. Upon conclusion of the relevant research and development project, we will amortize the acquired IPR&D over its estimated useful life or expense the acquired IPR&D should the research and development project be unsuccessful with no future alternative use. We base the useful lives and related amortization expense on our estimate of the period that the assets will generate revenues or otherwise be used. We assess the carrying value of our IPR&D assets at least annually, or more frequently if an event occurs indicating the potential for impairment, which requires us to make assumptions and judgements regarding the future cash flows of these assets. If the assets are considered to be impaired, the impairment we recognize is the amount by which the carrying value of the assets exceeds the fair value of the assets. Fair value is determined by a combination of third-party sources and forecasted discounted cash flows. Goodwill is reviewed for impairment at least annually, or more frequently if an event occurs indicating the potential for impairment. During the impairment review process, we consider qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit is less than the carrying amount, including goodwill. If we determine that it is not more likely than not that the fair value of our reporting unit is less than the carrying amount, then no additional assessment is deemed necessary. Otherwise, we perform the two-step
Revenue Recognition		Revenue Recognition In May 2014, the Financial Accounting Standards Board (“FASB”) issued accounting guidance on the recognition of revenue from customers. This guidance supersedes the revenue recognition requirements we previously followed in Accounting Standards Codification, or ASC, Topic 605, Revenue Recognition Revenue from Contracts with Customers, We generate revenues from payments received under a collaboration arrangement which included payments for nonrefundable fees at the inception of the agreement, license fees, milestone-based payments and reimbursements for research and development efforts. As of January 1, 2018, we adopted ASC 606, Revenue from Contracts with Customers Prior to the ASC 606 adoption, revenue was recognized when all the following criteria were met; (i) persuasive evidence of an arrangement exists; (ii) delivery has occurred or services have been rendered; (iii) the seller’s price to the buyer is fixed or determinable; and (iv) collectability is reasonably assured. Under the previous guidance, we recognized the upfront payment received from our collaborative partner on a straight- line basis over the performance period arrangement or from receipt until May 2036. There were no other adoption differences in revenue recognized due to the transition from the previously applied authoritative accounting literature to ASC 606. Upon the adoption of ASC 606, we concluded that all services had been rendered over the research period and recognized an adjustment to decrease deferred revenues and accumulated deficit by approximately $0.9 million. The impact of applying the provisions of ASC 606 in the year ended December 31, 2018 was to decrease revenues by forty-six
Revenue under Collaborative Agreements		Revenue under Collaborative Agreements We entered into a collaboration and license agreement (“the agreement”) with a specialty pharmaceutical company for the development and commercialization of products and product candidates for the treatment of various diseases and conditions relating to the field of oncology. Pursuant to the terms of the original agreement and related amendment, the collaborator made an upfront non-refundable Our collaboration partner can select additional compounds to add to the licenses granted. We consider these rights to be options without material rights, as these rights require additional fees and future royalties which do not represent discounts to similar licenses to a new collaboration partner. We consider grants of additional licenses upon exercises to be separate contracts. Under the collaboration agreement, we have identified a pre-clinical co-development The transaction price is the amount of consideration to which we expect to be entitled for transferring promised goods or services. The transaction price does not include amounts subject to uncertainties unless it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated to the amount is resolved. Upfront fees are contractually obligated and included in the transaction price. Consideration we may have received in exchange for milestones achieved were subject to significant uncertainties inherent in product development and were not included in the transaction price until deemed probable that the amount would not result in a significant reversal of revenue in the future. At the conclusion of each reporting period, we reassessed the probability of milestone achievement and expected payments for research and development services, and if necessary, adjusted our total estimated transaction price. As our collaboration agreement had one distinct bundle of performance obligations comprised of services and licenses delivered concurrently and were not subject to the right of return, allocation of the transaction price was not required. Upfront amounts allocated to licenses and ongoing services were recognized as revenue commencing upon transfer of the licenses over the research period of the target on a percentage of total costs to be incurred basis. We completed our ongoing services under the collaboration agreement during the fourth quarter of 2017 and therefore considered our performance obligations to have been fully satisfied at that time. Development milestones are recognized as revenue when the consideration is included in the transaction price over the remaining term of the research period. Royalties will be recognized when the underlying sales occur based on estimates. We will record a true-up We provide standard indemnification and protection of licensed intellectual property for our customers. These provisions are part of assurance that the licenses meet the agreement’s representations and are not an obligation to provide goods or services.
Research and Development Expenses		Research and Development Expenses Research and development expenses include salaries and benefits, facilities and other overhead expenses, external clinical trial expenses, research related manufacturing services, contract services and other outside expenses. Research and development expenses are charged to operating expenses as incurred when these expenditures relate to our research and development efforts and have no alternative future uses. Reimbursed research and development costs under government grant arrangements are recorded as a reduction to research and development expenses and are recognized in the period in which the related costs are incurred. We are obligated to make upfront payments upon execution of certain research and development agreements. Advance payments, including nonrefundable amounts, for goods or services that will be used or rendered for future research and development activities are deferred. Such amounts are recognized as expense as the related goods are delivered or the related services are performed, or such time when we do not expect the goods to be delivered or services to be performed.
Clinical Trial Expenses		Clinical Trial Expenses We make payments in connection with our clinical trials under contracts with contract research organizations that support conducting and managing clinical trials. The financial terms of these agreements are subject to negotiation and vary from contract to contract and may result in uneven payment flows. Generally, these agreements set forth the scope of work to be performed at a fixed fee, unit price or on a time and materials basis. A portion of our obligation to make payments under these contracts depends on factors such as the successful enrollment or treatment of patients or the completion of other clinical trial milestones. Expenses related to clinical trials are accrued based on our estimates and/or representations from service providers regarding work performed, including actual level of patient enrollment, completion of patient studies and progress of the clinical trials. Other incidental costs related to patient enrollment or treatment are accrued when reasonably certain. If the amounts we are obligated to pay under our clinical trial agreements are modified (for instance, as a result of changes in the clinical trial protocol or scope of work to be performed), we adjust our accruals accordingly. Revisions to our contractual payment obligations are charged to expense in the period in which the facts that give rise to the revision become reasonably certain.
Share-Based Compensation		Share-Based Compensation We record share-based compensation expense associated with equity instruments in accordance with the authoritative guidance for stock-based compensation. The cost of employee services received in exchange for an award of an equity instrument is measured at the grant date based on the estimated fair value of the award and is recognized as expense on a straight-line basis over the requisite service period of the award. Share-based compensation expense for an award with a performance condition is recognized when the achievement of such performance condition is determined to be probable. If the outcome of such performance condition is not determined to be probable or is not met, no compensation expense is recognized, and any previously recognized compensation expense is reversed. Forfeitures are recognized as a reduction of share-based compensation expense as they occur.
Income Taxes		Income Taxes Deferred income taxes are recognized for the tax consequences in future years of differences between the tax basis of assets and liabilities and their financial reporting amounts at each year end based on enacted tax laws and statutory tax rates applicable to the periods in which the differences are expected to affect taxable income. A provision has been made for income taxes due on taxable income and for the deferred taxes on temporary differences. Deferred tax assets and liabilities are adjusted for the effects of changes in tax laws and rates on the date of enactment. Realization of the deferred income tax asset is dependent on gathering sufficient taxable income in future years. Valuation allowances are established when necessary to reduce deferred tax assets to the amount expected to be realized. Income tax expense is the combination of the tax payable for the period and the change during the period in deferred tax assets and liabilities. We follow the accounting guidance on accounting for uncertainty in income taxes. The guidance prescribes a recognition threshold and measurement attribute criteria for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities based on the technical merits of the position.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is equal to net loss for the periods ended March 31, 2020 and 2019.	Comprehensive Loss Comprehensive loss is equal to net loss for the years ended December 31, 2018 and 2019.
Net Loss per Class A Common Unit		Net Loss per Class A Common Unit Basic net loss per Class A common unit is computed by dividing net loss, after adjusting for preferred unit dividends, if declared by the weighted-average number of Class A common units outstanding during the period. Diluted net loss per common unit is computed using the weighted-average number of Class A common units outstanding during the period and, if dilutive the weighted average number of potential shares of Class A common units. The effect of the conversion of preferred units into Class A common units is excluded from the computation of diluted net loss per common unit for the period as their effect is antidilutive. Additionally, Class A common unit equivalents are excluded from the computation of diluted net loss per common unit for all periods as their effect is antidilutive.
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, 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, 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 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, 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.	Adoption and Pending Adoption of Recent Accounting Pronouncements The following table provides a brief description of recently issued accounting standards, those adopted in the current period and those not yet adopted: Standard Description Effective Date Effect on the Financial In January 2016, the FASB issued ASU 2016-01, The new guidance supersedes the guidance to classify equity securities with readily determinable fair values into different categories (that is, trading or available-for-sale) January 1, 2018 We currently do not hold equity securities and therefore the adoption did not have a material impact on our consolidated financial position or results of operations. In May 2014, the FASB issued ASU 2014-09, The new standard will supersede nearly all existing revenue recognition guidance. Under Topic 606, an entity is required to recognize revenue upon transfer of promised goods or services to customers in an amount that reflects the expected consideration to be received in exchange for those goods or services. Topic 606 defines a five-step process in order to achieve this core principle, which may require the use of judgment and estimates, and also requires expanded qualitative and quantitative disclosures relating to the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers, including significant judgments and estimates used. The new standard also defines accounting for certain costs related to origination and fulfillment of contracts with customers, including whether such costs should be capitalized. The new standard permits adoption either by using (i) a full retrospective approach for all periods presented in the period of adoption or (ii) a modified retrospective approach where the new standard is applied in the financial statements starting with the year January 1, 2019 We have adopted the new guidance on January 1, 2018 using the modified retrospective approach. Refer to Note 2 “Revenue Recognition” for additional detail regarding the impact of the adoption. of adoption. Under both approaches, cumulative impact of the adoption is reflected as an adjustment to retained earnings (accumulated equity (deficit)) as of the earliest date presented in accordance with the new standard. In June 2018, the FASB issued ASU 2018-07, The FASB issued the new guidance as part of its ongoing Simplification Initiative. The ASU supersedes Subtopic 505-50 January 1, 2019 We have adopted the new guidance on January 1, 2018. The impact of the adoption was not material to the consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, This guidance revises the accounting related to leases by requiring lessees to recognize a lease liability and a right-of-use January 1, 2019 We have adopted Topic 842 on January 1, 2019 using a modified retrospective transition basis for leases existing as of the period of adoption. We implemented new processes and used the available practical expedients to implement the guidance. The practical expedients allowed us to carry forward our historical assessment of whether existing agreements are or contain a lease and the classification of our existing lease arrangements. All of our real-estate operating lease commitments are recognized as lease liabilities with corresponding right-of-use and liabilities of the consolidated balance sheet of $1.5 million, using an assumed weighted average discount rate of 11.0%. The adoption did not have an impact on our consolidated statements of operations and did not require recognition of a cumulative-effect adjustment to the opening balance of accumulated deficit in the period of adoption. We elected to continue applying the guidance under ASU 840, Leases for comparative periods, as allowed through ASU 2018-11, In June 2016, the FASB issued ASU 2016-13, 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 do not believe the adoption will have a material impact on our consolidated financial position or results of operations. 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, 2021 We do not believe the adoption will have a material impact on our consolidated financial position or results of operations.
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.

Business Combinations (Tables)

Business Combinations (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Business Combinations [Abstract]
Schedule of Assets and Liabilities of VIE	Total assets and liabilities of Kalyra as of March 31, 2020 and December 31, 2019 are as follows (in thousands): March 31, December 31, 2020 2019 Cash and cash equivalents $ 286 $ 712 Other current assets 77 21 In-process research 8,800 8,800 Goodwill 3,736 3,736 Other long-term assets — 14 Accounts payable and accrued expenses 113 391 Deferred tax liability 2,463 2,463 Noncontrolling interests $ 6,712 $ 6,821	Total assets and liabilities of Kalyra as of December 31, 2018 and 2019 are as follows (in thousands): December 31, 2018 2019 Cash and cash equivalents $ 1,482 $ 712 Other current assets 933 21 In-process 8,800 8,800 Goodwill 3,736 3,736 Other long-term assets 48 14 Accounts payable and accrued expenses 1,224 391 Deferred tax liability 2,463 2,463 Noncontrolling interests $ 7,536 $ 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): March 31, March 31, 2020 2019 Noncontrolling interest at beginning of period $ 6,821 $ 7,536 Net loss attributable to noncontrolling interest (109 ) (320 ) Noncontrolling interest at end of period $ 6,712 $ 7,216	The following is a reconciliation of equity (net assets) attributable to the noncontrolling interest (in thousands): December 31, 2018 2019 Noncontrolling interest at beginning of period $ 9,885 $ 7,536 Net loss attributable to noncontrolling interest (2,365 ) (715 ) Issuance of VIE shares under equity incentive plan 16 — Noncontrolling interest at end of period $ 7,536 $ 6,821

Prepaid Expenses and Other As_2

Prepaid Expenses and Other Assets (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
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): March 31, December 31, 2020 2019 Prepaid insurance $ 303 $ 150 Prepaid software licenses and maintenance 299 238 Prepaid research and development expenses 3,668 2,985 Other prepaid expenses 303 266 Total prepaid expenses and other current assets 4,573 3,639 Less long-term portion 2,353 2,134 Total prepaid expenses and other assets, current $ 2,220 $ 1,505	Prepaid expenses and other assets consisted of the following (in thousands): December 31, 2018 2019 Prepaid insurance $ 98 $ 150 Prepaid software licenses and maintenance 126 238 Prepaid research and development expenses 1,715 2,985 Prepaid rent and related security deposits 104 168 Other prepaid expenses 88 98 Total prepaid expenses and other current assets 2,131 3,639 Less long-term portion 1,525 2,134 Total prepaid expenses and other assets, current $ 606 $ 1,505

Property and Equipment, net (Ta

Property and Equipment, net (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment, net	Property and equipment, net consisted of the following (in thousands): March 31, December 31, 2020 2019 Computer and Office Equipment $ 271 $ 243 Lab Equipment 401 401 Leasehold Improvements 24 24 Construction in Progress 28 — Subtotal 724 668 Accumulated depreciation and amortization (205 ) (167 ) Property and equipment, net $ 519 $ 501	Property and equipment, net consisted of the following (in thousands): December 31, 2018 2019 Computer and Office Equipment $ 39 $ 243 Lab Equipment 277 401 Leasehold Improvements — 24 Subtotal 316 668 Accumulated depreciation and amortization (56 ) (167 ) Property and equipment, net $ 260 $ 501

Accrued Expenses (Tables)

Accrued Expenses (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consist of the following (in thousands): March 31, December 31, 2020 2019 Accrued research and development expenses $ 5,103 $ 5,465 Accrued employee expenses 2,008 2,977 Accrued general and administrative expenses 1,916 1,356 Lease liability 810 781 Other 83 29 Total accrued expenses $ 9,920 $ 10,608	Accrued expenses consist of the following (in thousands): December 31, 2018 2019 Accrued research and development expenses $ 1,137 $ 5,465 Accrued employee expenses 1,023 2,977 Accrued general and administrative expenses 356 1,356 Lease liability, current portion — 781 Other 38 29 Total accrued expenses $ 2,554 $ 10,608

Convertible Preferred Units (Ta

Convertible Preferred Units (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Equity [Abstract]
Schedule of Temporary Equity	The authorized, issued, and outstanding shares of convertible preferred units at March 31, 2020 and December 31, 2019 were as follows: March 31, 2020 Series Units Shares Issued Liquidation Carrying Value Series A convertible preferred units 1,579,309 1,579,309 $ 18,319,984 $ 18,225,809 Series B convertible preferred units 3,523,739 3,523,739 43,800,076 41,603,945 Series C convertible preferred units 5,714,300 5,714,300 100,000,250 96,104,453 Total 10,817,348 10,817,348 $ 162,120,310 $ 155,934,207 December 31, 2019 Series Units Shares Issued Liquidation Carrying Value Series A convertible preferred units 1,579,309 1,579,309 $ 18,319,984 $ 18,225,809 Series B convertible preferred units 3,523,739 3,523,739 43,800,076 41,603,945 Series C convertible preferred units 5,714,300 4,847,106 84,824,355 81,876,092 Total 10,817,348 9,950,154 $ 146,944,415 $ 141,705,846	The authorized, issued, and outstanding shares of convertible preferred units at December 31, 2018 and 2019 were as follows: December 31, 2018 Series Units Shares Issued Liquidation Carrying Value Series A convertible preferred units 1,638,000 1,579,309 $ 18,319,984 $ 18,225,809 Series B convertible preferred units 3,621,000 3,523,739 43,800,076 41,603,945 Total 5,259,000 5,103,048 $ 62,120,060 $ 59,829,754 December 31, 2019 Series Units Shares Issued Liquidation Carrying Value Series A convertible preferred units 1,579,309 1,579,309 $ 18,319,984 $ 18,225,809 Series B convertible preferred units 3,523,739 3,523,739 43,800,076 41,603,945 Series C convertible preferred units 5,714,300 4,847,106 84,824,355 81,876,092 Total 10,817,348 9,950,154 $ 146,944,415 $ 141,705,846

Members' Equity (Tables)

Members' Equity (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Equity [Abstract]
Schedule of Valuation Assumptions of Profit Interest Awards	The fair value of the profit interest awards is estimated using an option pricing model with the following assumptions: Three Months Ended March 31, 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 1.3 Lack of marketability discount 26.5 % 1.9 % Grant date fair value $ 3.06 $ 1.88	The fair value of the profit interest awards is estimated using an option pricing model with the following assumptions: Year ended December 31, 2018 2019 Members’ equity value (in thousands) $ 113,100 $ 197,041 - $271,207 Threshold amounts (in thousands) $ 134,000 - $143,800 $ 143,800 - $309,824 Risk free rate 2.8 % 1.5 % Volatility 75.0 % 75.0 % Time to liquidity (in years) 1.3 1.1 - 1.8 Lack of marketability discount 25.0 % 18.8% - 26 .4% Grant date fair value $ 1.85 - $2.01 $ 1.88 - $3.06
Schedule of Class B Incentive Units and Weighted Average Fair Value		The following table provides a summary of the Class B common unit activity under the Plan. The amounts include incentive units granted to both employees and non-employees: Number of Units Weighted Average Fair Value Outstanding at December 31, 2017 703,000 $ 1.47 Granted 947,166 $ 1.62 Forfeited (37,855 ) $ 1.47 Outstanding at December 31, 2018 1,612,311 $ 1.56 Granted 1,095,545 $ 2.73 Forfeited (37,188 ) $ 1.62 Outstanding at December 31, 2019 2,670,668 $ 2.04
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 2020 2019 Research and development expense $ 136 $ 66 General and administrative expense 193 63 Total share-based compensation expense $ 329 $ 129	During 2018 and 2019, the share-based compensation expense included in the statement of operations was as follows: Year ended 2018 2019 Research and development expense $ 158 $ 339 General and administrative expense 150 278 Total share-based compensation expense $ 308 $ 617

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Schedule of Weighted Average Remaining Lease term and Discount rates		The following table presents the weighted average remaining lease term and weighted average discount rates related to our operating leases as of December 31, 2019: Cash paid in 2019 related to operating leases (in thousands) $ 700 Weighted average remaining lease term (in years) 2.9 Weighted average discount rate 11.0 %
Schedule of Future Minimum Operating Lease Payments	Approximate annual future minimum operating lease payments as of March 31, 2020 are as follows (in thousands): Year Operating 2020 $ 765 2021 1,044 2022 661 2023 187 Total minimum lease payments: 2,657 Less: imputed interest (363 ) Total operating lease liabilities 2,294	Approximate annual future minimum operating lease payments as of December 31, 2019 are as follows (in thousands): Year-ending December 31, Payment Amount 2020 $ 1,015 2021 1,044 2022 661 2023 187 Total minimum lease payments: 2,907 Less: imputed interest (431 ) Total operating lease liabilities 2,476 Less: current portion 781 Lease liability, net of current portion $ 1,695

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit	The following table presents the current and deferred income tax provision (benefit) for federal and state income taxes (in thousands): 2018 2019 Current tax provision: Federal $ — $ — State 4 15 Total current tax provision 4 15 Deferred tax provision: Federal — — State — — Total deferred tax provision — — Total provision for income taxes: $ 4 $ 15
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of the expected tax computed at the U.S. statutory federal income tax rate to the total provision for income taxes at December 31 follows (in thousands): 2018 2019 Expected tax at 21% $ (4,921 ) 21.0 % $ (9,730 ) 21.0 % State income tax, net of federal tax (1,581 ) 6.8 % (3,167 ) 6.8 % Limited liability company loss 8 -0.1 % 4 -0.0 % Non-deductible 187 -0.8 % 164 -0.3 % Research credits (1,145 ) 4.9 % (1,424 ) 3.1 % Other 191 -0.8 % (2 ) 0.0 % Change in valuation allowance 7,265 -31.0 % 14,170 -30.6 % Provision for income taxes $ 4 0.0 % $ 15 0.0 %
Schedule of Deferred Tax Assets (Liabilities)	Significant components of our net deferred tax asset or liability at December 31, 2018 and 2019 are as follows (in thousands): 2018 2019 Deferred tax assets Net operating loss $ 12,425 $ 25,053 Compensation 13 148 Deferred rent 5 — ASC 842 lease liability — 693 State tax 1 1 Research credits 2,079 3,503 Total gross deferred tax assets 14,523 29,398 Valuation allowance (14,477 ) (28,647 ) Net deferred tax assets 46 751 Deferred tax liabilities Depreciable assets (46 ) (97 ) ASC 842 right of use asset — (654 ) In-process (2,463 ) (2,463 ) Deferred tax liabilities (2,509 ) (3,214 ) Net deferred tax liabilities $ (2,463 ) $ (2,463 )
Reconciliation of Unrecognized Tax Benefits	The following table reconciles the beginning and ending amount of unrecognized tax benefits for the year ended December 31, 2018 and 2019 (in thousands): 2018 2019 Gross unrecognized tax benefits at the beginning of the year $ 325 $ 741 Additions from tax positions taken in the current year 416 383 Gross unrecognized tax benefits at end of the year $ 741 $ 1,124

Net Loss Per Class A Common U_2

Net Loss Per Class A Common Unit (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Loss Per Unit	Basic and diluted net loss per Class A common unit were calculated as follows (in thousands except per unit amounts): Three Months Ended 2020 2019 Numerator: Net loss attributable to Zentalis Pharmaceuticals, LLC $ (16,126 ) $ (8,343 ) Denominator: Weighted average number of Class A common units outstanding, basic and diluted 5,601 5,594 Net loss per Class A common unit $ (2.88 ) $ (1.49 )	Basic and diluted net loss per Class A common unit were calculated as follows (in thousands except per share amounts): Year ended 2018 2019 Net loss attributable to Zentalis Pharmaceuticals, LLC $ (21,067 ) $ (45,663 ) Weighted average number of Class A common units outstanding, basic and diluted 5,594 5,597 Net loss per Class A common unit $ (3.77 ) $ (8.16 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Unit	The following Class A common unit equivalents have been excluded from the calculations of diluted net loss per Class A common unit because their inclusion would be antidilutive (in thousands). Three Months Ended 2020 2019 Preferred units, as if converted to Class A common units 10,817 5,103 Incentive units—Class B common units 2,607 1,660 13,424 6,763	The following Class A common unit equivalents have been excluded from the calculations of diluted net loss per Class A common unit because their inclusion would be antidilutive (in thousands). Year ended 2018 2019 Preferred units, as if converted to Class A common units 5,103 9,950 Incentive units—Class B common units 1,612 2,671 6,715 12,621
Schedule of Pro forma Earnings Per Share, Basic and Diluted		The unaudited pro forma basic and diluted weighted average common unit outstanding used in the calculation of unaudited pro forma basic and diluted net loss per unit attributable to common unit holders for the year ended December 31, 2019 has been prepared to give effect to the conversion of Zentalis Pharmaceuticals, LLC to a C-corporation, Year ended Net loss attributable to Zentalis Pharmaceuticals, LLC common units—basic and diluted $ (45,663 ) Weighted average number of common units outstanding 8,815 Pro forma adjustments to reflect automatic conversion of convertible preferred units to common stock upon the completion of the proposed initial public offering 9,237 Pro forma weighted average number of shares outstanding—basic and diluted 18,058 Pro forma net loss per common share $ (2.53 )

Subsequent Events (Tables)

Subsequent Events (Tables)	12 Months Ended
	Dec. 31, 2019
Subsequent Events [Abstract]
Schedule of Future Minimum Lease Payments	The expected future minimum lease obligations under the agreement are as follows (in thousands): Year-ending December 31, Payment 2021 $ 2,018 2022 2,078 2023 2,140 2024 2,205 2025 2,271 Thereafter 12,419 Total minimum lease payments: $ 23,131

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 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, 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, 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 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, 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.

Organization and Business (Deta

Organization and Business (Detail) $ / shares in Units, $ in Thousands	Apr. 07, 2020USD ($)$ / sharesshares	Apr. 02, 2020$ / sharesshares	Dec. 21, 2017
Class of Stock [Line Items]
Exchange ratio			1
Subsequent Event
Class of Stock [Line Items]
Proceeds from initial public offering | $	$ 190,000
Issuance fees and expenses | $	17,600
Subsequent Event | IPO
Class of Stock [Line Items]
Share price (in dollars per sharee) | $ / shares		$ 18
Proceeds from initial public offering | $	190,000
Issuance fees and expenses | $	$ 17,600
Subsequent Event | 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
Subsequent Event | 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	1,377,000
Subsequent Event | Restricted Common Stock | IPO
Class of Stock [Line Items]
Number of shares converted (in shares) | shares		1,160,277

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Mar. 31, 2020	Jan. 01, 2019	Dec. 21, 2017
Accounting Policies [Line Items]
Restricted cash	$ 243,000		$ 411,000
Allowance for doubtful accounts	0	$ 0
Lease liability	2,476,000		2,294,000
Right-of-use asset	$ 2,335,000		$ 2,276,000
Weighted average discount rate	11.00%
Revision of Prior Period, Accounting Standards Update, Adjustment
Accounting Policies [Line Items]
Decrease in accumulated deficit		(900,000)
Increase or decrease in deferred revenue		(900,000)
Decrease in revenue		(46,000)
Calculated under Revenue Guidance in Effect before Topic 606
Accounting Policies [Line Items]
Increase or decrease in deferred revenue		$ 800,000
Equipment | Minimum
Accounting Policies [Line Items]
Property plant and equipment useful life	Three years
Equipment | Maximum
Accounting Policies [Line Items]
Property plant and equipment useful life	Five years
Accounting Standards Update 2016-02
Accounting Policies [Line Items]
Lease liability				$ 1,500,000
Right-of-use asset				$ 1,500,000
Weighted average discount rate				11.00%
Collateral Pledged
Accounting Policies [Line Items]
Restricted cash	$ 200,000
Kalyra Pharmaceuticals, Inc.
Accounting Policies [Line Items]
Ownership percentage					25.00%

Business Combinations - Narrati

Business Combinations - Narrative (Detail) - 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 (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 63,650	$ 67,246	$ 16,107	$ 25,154
In-process research and development	8,800	8,800		8,800
Goodwill	3,736	3,736		3,736
Deferred tax liability	2,463	2,463		2,463
Noncontrolling interests	6,712	6,821	$ 7,216	7,536	$ 9,885
VIE, Primary Beneficiary
Variable Interest Entity [Line Items]
Cash and cash equivalents	286	712		1,482
Other current assets	77	21		933
In-process research and development	8,800	8,800		8,800
Goodwill	3,736	3,736		3,736
Other long-term assets	0	14		48
Accounts payable and accrued expenses	113	391		1,224
Deferred tax liability	2,463	2,463		2,463
Noncontrolling interests	$ 6,712	$ 6,821		$ 7,536

Business Combinations - Rollfor

Business Combinations - Rollforward of Noncontrolling Interest (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Noncontrolling interest at beginning of period	$ 6,821	$ 7,536	$ 7,536	$ 9,885
Net loss attributable to noncontrolling interest	(109)	(320)	(715)	(2,365)
Issuance of VIE shares under equity incentive plan				16
Noncontrolling interest at end of period	$ 6,712	$ 7,216	$ 6,821	$ 7,536

Fair Value Measurement (Detail)

Fair Value Measurement (Detail) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Money Market Funds | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, fair value disclosure	$ 60.3	$ 63	$ 23.2

Prepaid Expenses and Other As_3

Prepaid Expenses and Other Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid insurance	$ 303	$ 150	$ 98
Prepaid software licenses and maintenance	299	238	126
Prepaid research and development expenses	3,668	2,985	1,715
Prepaid rent and related security deposits		168	104
Other prepaid expenses	303	266
Other prepaid expenses		98	88
Total prepaid expenses and other current assets	4,573	3,639	2,131
Less long-term portion	2,353	2,134	1,525
Total prepaid expenses and other assets, current	$ 2,220	$ 1,505	$ 606

Property and Equipment, net - S

Property and Equipment, net - Summary (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Subtotal	$ 724	$ 668	$ 316
Accumulated depreciation and amortization	(205)	(167)	(56)
Property and equipment, net	519	501	260
Computer and Office Equipment
Property, Plant and Equipment [Line Items]
Subtotal	271	243	39
Lab Equipment
Property, Plant and Equipment [Line Items]
Subtotal	401	401	$ 277
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Subtotal	24	24
Construction in Progress
Property, Plant and Equipment [Line Items]
Subtotal	$ 28	$ 0

Property and Equipment, net - N

Property and Equipment, net - Narrative (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Depreciation and amortization	$ 38	$ 21	$ 111	$ 51

Accrued Expenses (Detail)

Accrued Expenses (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Accrued research and development expenses	$ 5,103	$ 5,465	$ 1,137
Accrued employee expenses	2,008	2,977	1,023
Accrued general and administrative expenses	1,916	1,356	356
Lease liability	810	781
Other	83	29	38
Total accrued expenses	$ 9,920	$ 10,608	$ 2,554

Convertible Preferred Units - N

Convertible Preferred Units - Narrative (Detail) - USD ($)	1 Months Ended				2 Months Ended	3 Months Ended		8 Months Ended	12 Months Ended
	Feb. 29, 2020	Sep. 30, 2019	Dec. 31, 2017	Sep. 30, 2015	Mar. 31, 2016	Mar. 31, 2020	Mar. 31, 2019	Aug. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Convertible preferred units issued (in shares)						867,000			4,847,000
Shares issued (in shares)						10,817,348			9,950,154
Net proceeds from issuance of convertible preferred units						$ 14,228,000	$ 0		$ 81,876,000	$ 9,456,000
Dividends declared						$ 0			$ 0	$ 0
Automatic conversion feature, minimum gross cash proceeds received in a public offering						$ 75,000,000			$ 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	$ 11.60			$ 11.60
Shares issued (in shares)					286,205	1,579,309			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				$ 100,000	$ 39,000
Conversion price (in dollars per share)						$ 11.60			$ 11.60
Liquidation preference (in dollars per share)						11.60			11.60
Series B Preferred Units
Class of Stock [Line Items]
Par value per share (in dollars per share)			$ 12.43			$ 12.43		$ 12.43	$ 12.43	$ 12.43
Shares issued (in shares)			2,735,320			3,523,739		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			$ 12.43
Liquidation preference (in dollars per share)						12.43			12.43
Series C Preferred Units
Class of Stock [Line Items]
Par value per share (in dollars per share)	$ 17.50	$ 17.50				$ 17.5			$ 17.50
Shares issued (in shares)	867,194	4,847,106				5,714,300			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			$ 17.50
Liquidation preference (in dollars per share)						$ 17.50			$ 17.50

Convertible Preferred Units - S

Convertible Preferred Units - Schedule of Units Authorized, Issued, and Outstanding (Detail) - USD ($)	Mar. 31, 2020	Feb. 29, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018	Aug. 31, 2018	Dec. 31, 2017	Mar. 31, 2016
Class of Stock [Line Items]
Units authorized (in shares)	10,817,348		10,817,348
Shares issued (in shares)	10,817,348		9,950,154
Shares outstanding (in shares)	10,817,348		9,950,154
Liquidation Value	$ 162,120,310		$ 146,944,415
Carrying Value	$ 155,934,207		$ 141,705,846
Series A Preferred Units
Class of Stock [Line Items]
Units authorized (in shares)	1,579,309		1,579,309
Shares issued (in shares)	1,579,309		1,579,309					286,205
Shares outstanding (in shares)	1,579,309		1,579,309
Liquidation Value	$ 18,319,984		$ 18,319,984
Carrying Value	$ 18,225,809		$ 18,225,809
Series B Preferred Units
Class of Stock [Line Items]
Units authorized (in shares)	3,523,739		3,523,739
Shares issued (in shares)	3,523,739		3,523,739			788,419	2,735,320
Shares outstanding (in shares)	3,523,739		3,523,739
Liquidation Value	$ 43,800,076		$ 43,800,076
Carrying Value	$ 41,603,945		$ 41,603,945
Series C Preferred Units
Class of Stock [Line Items]
Units authorized (in shares)	5,714,300		5,714,300
Shares issued (in shares)	5,714,300	867,194	4,847,106	4,847,106
Shares outstanding (in shares)	5,714,300		4,847,106
Liquidation Value	$ 100,000,250		$ 84,824,355
Carrying Value	$ 96,104,453		$ 81,876,092
Series A Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Convertible preferred units authorized (in shares)					1,638,000
Convertible preferred units issued (in shares)					1,579,309
Convertible preferred units outstanding (in shares)					1,579,309
Convertible preferred units liquidation Value					$ 18,319,984
Convertible preferred units carrying Value					$ 18,225,809
Series B Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Convertible preferred units authorized (in shares)					3,621,000
Convertible preferred units issued (in shares)					3,523,739
Convertible preferred units outstanding (in shares)					3,523,739
Convertible preferred units liquidation Value					$ 43,800,076
Convertible preferred units carrying Value					$ 41,603,945
Convertible Preferred Units
Class of Stock [Line Items]
Convertible preferred units authorized (in shares)					5,259,000
Convertible preferred units issued (in shares)					5,103,048
Convertible preferred units outstanding (in shares)					5,103,048
Convertible preferred units liquidation Value					$ 62,120,060
Convertible preferred units carrying Value					$ 59,829,754

Members' Equity - Narrative (De

Members' Equity - Narrative (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		12 Months Ended
	Dec. 31, 2017	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2019
Class of Stock [Line Items]
Common stock issued (in shares)	5,187,554			25,321,524	25,321,524
Common stock outstanding (in shares)	5,187,554			24,147,270	24,147,270
Common stock subject to future vesting provisions (in shares)	406,831
Series A Preferred Units
Class of Stock [Line Items]
Preferred units authorized (in shares)	1,638,000
Series B Preferred Units
Class of Stock [Line Items]
Preferred units authorized (in shares)	3,621,000
Class A Common Units
Class of Stock [Line Items]
Common units, authorized (in shares)	15,000,000	20,000,000		20,000,000	15,000,000	20,000,000
Common stock subject to future vesting provisions (in shares)				9,572	24,236
Stock issued (in shares)				7,093	0
Common units subject to future vesting conditions (in shares)				9,572
Class B Common Units
Class of Stock [Line Items]
Common units, authorized (in shares)	872,620	3,458,522		3,458,522	2,154,816	3,458,522
Stock issued (in shares)		70,000	47,500
Stock issued upon conversion of units (in shares)	703,000
Vested common units outstanding				1,008,479
Unvested common units outstanding		1,500,000		1,662,189
Shares for future grants				787,854
Profit Interest Awards
Class of Stock [Line Items]
Unrecognized compensation expense		$ 3.4		$ 3.8
Period for recognition of unrecognized compensation expense		3 years 2 months 12 days		3 years 4 months 24 days

Members' Equity - Fair Value As

Members' Equity - Fair Value Assumptions for Profit Interest Awards (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Members' equity value (in thousands)	$ (95,903)		$ (80,106)	$ 24,770
Profit Interest Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Members' equity value (in thousands)	271,207	$ 197,041		$ 113,100
Threshold amounts (in thousands)	$ 309,824	$ 143,800
Risk free rate (as a percent)	1.50%	1.50%	1.50%	2.80%
Volatility (as a percent)	75.00%	75.00%	75.00%	75.00%
Time to liquidity (in years)	1 year 1 month 6 days	1 year 3 months 19 days		1 year 3 months 18 days
Lack of marketability discount (as a percent)	26.50%	1.90%		25.00%
Grant date fair value (USD per share)	$ 3.06	$ 1.88
Minimum | Profit Interest Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Members' equity value (in thousands)			$ 197,041
Threshold amounts (in thousands)			$ 143,800	$ 134,000
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	$ 1.85
Maximum | Profit Interest Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Members' equity value (in thousands)			$ 271,207
Threshold amounts (in thousands)			$ 309,824	$ 143,800
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	$ 2.01

Members' Equity - Schedule of C

Members' Equity - Schedule of Class B Incentive Units and Weighted Average Fair Value (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Equity [Abstract]
Outstanding beginning balance	1,612,311	703,000
Granted	1,095,545	947,166
Forfeited	(37,188)	(37,855)
Outstanding Ending balance	2,670,668	1,612,311
Outstanding beginning balance	$ 1.56	$ 1.47
Granted	2.73	1.62
Forfeited	1.62	1.47
Outstanding ending balance	$ 2.04	$ 1.56

Members' Equity - Share-based C

Members' Equity - Share-based Compensation (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 329	$ 129	$ 617	$ 308
Research and development expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	136	66	339	158
General and administrative expense
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 193	$ 63	$ 278	$ 150

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	1 Months Ended			12 Months Ended
	Aug. 31, 2019ft²	Apr. 30, 2019ft²	Jan. 31, 2016ft²	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Mar. 31, 2020USD ($)
Lease rental expenses				$ 0.8	$ 0.4
Future minimum operating lease payments, 2019					1.8
Future minimum operating lease payments, 2020					$ 1.3
Operating lease, weighted-average remaining lease term				2 years 10 months 24 days		2 years 8 months 12 days
Total minimum lease payments on leases not yet commenced						$ 23.1
Operating leases not yet commenced, term						10 years
San Diego
office space leased | ft²	2,333		11,121
Lease expiration month and year	2022-02				2022-06
Percentage of annual increases throughout the term of the lease	3.00%		3.00%
Lease commencement month and year	2019-10
New York
office space leased | ft²		4,800
Percentage of annual increases throughout the term of the lease		3.00%
Lease commencement month and year		2019-05
Lease expiration month and year		Jun. 30, 2023

Commitment and Contingencies -

Commitment and Contingencies - Schedule of Weighted Average Remaining Lease term and Discount rates (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Cash paid in 2019 related to operating leases (in thousands)	$ 700
Weighted average remaining lease term (in years)	2 years 10 months 24 days	2 years 8 months 12 days
Weighted average discount rate	11.00%

Commitment and Contingencies _2

Commitment and Contingencies - Future Minimum Lease Payments (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
2020		$ 1,015
2020	$ 765
2021	1,044	1,044
2022	661	661
2023	187	187
Total minimum lease payments	2,657	2,907
Less: imputed interest	(363)	(431)
Total operating lease liabilities	2,294	2,476
Less: current portion	$ 810	781
Lease liability, net of current portion		$ 1,695

Income Taxes - Current and Defe

Income Taxes - Current and Deferred Income Tax Provision (Benefit) For Federal and State Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Current tax provision:
Federal			$ 0	$ 0
State			15	4
Total current tax provision			15	4
Deferred tax provision:
Federal			0	0
State			0	0
Total deferred tax provision			0	0
Provision for income taxes	$ 0	$ 3	$ 15	$ 4

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Expected Tax Computed at U.S. Statutory Federal Income Tax Rate to Total Provision for Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Expected tax at 21%			21.00%	21.00%
State income tax, net of federal tax			6.80%	6.80%
Limited liability company loss			0.00%	(0.10%)
Non-deductible expenses			(0.30%)	(0.80%)
Research credits			3.10%	4.90%
Other			0.00%	(0.80%)
Change in valuation allowance			(30.60%)	(31.00%)
Provision for income taxes			0.00%	0.00%
Expected tax at 21%			$ (9,730)	$ (4,921)
State income tax, net of federal tax			(3,167)	(1,581)
Limited liability company loss			4	8
Non-deductible expenses			164	187
Research credits			(1,424)	(1,145)
Other			(2)	191
Change in valuation allowance			14,170	7,265
Provision for income taxes	$ 0	$ 3	$ 15	$ 4

Income Taxes - Components of Ne

Income Taxes - Components of Net Deferred Tax Asset or Liability (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets
Net operating loss	$ 25,053	$ 12,425
Compensation	148	13
Deferred rent		5
ASC 842 lease liability	693
State tax	1	1
Research credits	3,503	2,079
Total gross deferred tax assets	29,398	14,523
Valuation allowance	(28,647)	(14,477)
Net deferred tax assets	751	46
Deferred tax liabilities
Depreciable assets	(97)	(46)
ASC 842 right of use asset	(654)
In-process research and development	(2,463)	(2,463)
Deferred tax liabilities	(3,214)	(2,509)
Net deferred tax liabilities	$ (2,463)	$ (2,463)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Valuation allowance	$ 28,647	$ 14,477
Federal
Net operating loss carryforwards	89,200	44,100
Income tax credit carryforwards	2,300	1,300
Federal | Tax Year 2017 [Member]
Net operating loss carryforwards	68,200
Federal | Tax Year 2018 [Member]
Net operating loss carryforwards	21,000
State and Local
Net operating loss carryforwards	90,400	45,400
Income tax credit carryforwards	$ 1,400	$ 900

Income Taxes - Reconciliation_2

Income Taxes - Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits at the beginning of the year	$ 741	$ 325
Additions from tax positions taken in the current year	383	416
Gross unrecognized tax benefits at end of the year	$ 1,124	$ 741

Net Loss Per Class A Common U_3

Net Loss Per Class A Common Unit - Calculation (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net loss attributable to Zentalis Pharmaceuticals, LLC	$ (16,126)	$ (8,343)	$ (45,663)	$ (21,067)
Denominator:
Weighted average number of Class A common units outstanding, basic and diluted (in shares)	5,601	5,594	5,597	5,594
Net loss per Class A common unit (USD per share)	$ (2.88)	$ (1.49)	$ (8.16)	$ (3.77)

Net Loss Per Class A Common U_4

Net Loss Per Class A Common Unit - Antidilutive Securities (Detail) - shares shares in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per unit (in shares)	13,424	6,763	12,621	6,715
Convertible Preferred Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per unit (in shares)	10,817	5,103	9,950	5,103
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)	2,607	1,660	2,671	1,612

Net Loss Per Class A Common U_5

Net Loss Per Class A Common Unit - Unaudited Pro Forma (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Common Stock [Line Items]
Net loss attributable to Zentalis Pharmaceuticals, LLC	$ (16,126)	$ (8,343)	$ (45,663)	$ (21,067)
Weighted average number of Class A common units outstanding, basic and diluted (in shares)	5,601	5,594	5,597	5,594
Net loss per Class A common unit (USD per share)	$ (2.88)	$ (1.49)	$ (8.16)	$ (3.77)
Pro Forma
Common Stock [Line Items]
Net loss attributable to Zentalis Pharmaceuticals, LLC			$ (45,663)
Weighted average number of common units outstanding			8,815
Pro forma adjustments to reflect automatic conversion of convertible preferred units to common stock upon the completion of the proposed initial public offering			$ 9,237
Weighted average number of Class A common units outstanding, basic and diluted (in shares)			18,058
Net loss per Class A common unit (USD per share)			$ (2.53)

Related Party Disclosures (Deta

Related Party Disclosures (Detail) - USD ($)	Dec. 21, 2017	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Affiliated Entity | Master Services Agreement
Related Party Transaction [Line Items]
Expenses from transactions with related party		$ 17,000	$ 5,000	$ 5,000	$ 1,300,000
Due to related parties		17,000	5,000	17,000	1,200,000
Affiliated Entity | Intercompany Services Agreement
Related Party Transaction [Line Items]
Revenue from related parties		100,000	200,000	700,000	500,000
Due from related parties		$ 100,000	$ 800,000	$ 200,000	$ 500,000
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
VIE, Primary Beneficiary | Series B Preferred Units | Kalyra Pharmaceuticals, Inc.
Related Party Transaction [Line Items]
Number of shares acquired (in shares)	17,307,692

Subsequent Events (Detail)

Subsequent Events (Detail) $ / shares in Units, $ in Thousands	Apr. 07, 2020USD ($)$ / sharesshares	Apr. 02, 2020$ / sharesshares	Feb. 29, 2020USD ($)$ / sharesshares	Jan. 31, 2020ft²	Sep. 30, 2019USD ($)$ / sharesshares	Mar. 31, 2020USD ($)$ / sharesshares	Mar. 31, 2019USD ($)	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares
Subsequent Event [Line Items]
Shares issued (in shares) | shares						10,817,348		9,950,154
Net proceeds from issuance of convertible preferred units | $						$ 14,228	$ 0	$ 81,876	$ 9,456
Common stock, shares authorized (in shares) | shares								250,000,000	250,000,000
Common stock, par value (in dollars per share) | $ / shares								$ 0.001	$ 0.001
Series C Preferred Units
Subsequent Event [Line Items]
Shares issued (in shares) | shares			867,194		4,847,106	5,714,300		4,847,106
Par value per share (in dollars per share) | $ / shares			$ 17.50		$ 17.50	$ 17.5		$ 17.50
Gross proceeds from issuance of convertible preferred units | $			$ 15,200		$ 84,800
Net proceeds from issuance of convertible preferred units | $			14,200		81,900
Issuance costs of financing | $			$ 1,000		$ 2,900
Subsequent Event
Subsequent Event [Line Items]
Area of land | ft²				36,955
Lease description				The targeted lease commencement date is January 2021 and will continue for 120 months thereafter. The lease is subject to approximately 3% annual increases throughout the term of the lease.
Percentage of Annual lease incremental				3.00%
Extention lease term description				The agreement contains extension rights allowing us to extend the term of the lease for five years at the then market rate.
Issuance costs of financing | $	$ 17,600
Common stock, shares authorized (in shares) | shares		250,000,000
Common stock, par value (in dollars per share) | $ / shares		$ 0.001
Preferred stock, shares authorized (in shares) | shares		10,000,000
Preferred stock, par value (in dollars per share) | $ / shares		$ 0.001
Proceeds from initial public offering | $	190,000
Subsequent Event | IPO
Subsequent Event [Line Items]
Issuance costs of financing | $	17,600
Stock issued (in dollars per share) | $ / shares		$ 18
Proceeds from initial public offering | $	$ 190,000
Subsequent Event | Common Stock | Corporate Conversion
Subsequent Event [Line Items]
Stock issued (in shares) | shares		0
Subsequent Event | Common Stock | IPO
Subsequent Event [Line Items]
Stock issued (in dollars per share) | $ / shares	$ 18
Stock issued upon conversion of units (in shares) | shares		25,288,854
Stock issued (in shares) | shares	10,557,000
Stock issued (in dollars per share) | $ / shares	$ 18
Subsequent Event | Common Stock | Underwriters
Subsequent Event [Line Items]
Stock issued (in shares) | shares	1,377,000
Stock issued (in dollars per share) | $ / shares	$ 18
Subsequent Event | Restricted Common Stock | IPO
Subsequent Event [Line Items]
Stock issued upon conversion of units (in shares) | shares		1,160,277
Subsequent Event | Series C Preferred Units
Subsequent Event [Line Items]
Shares issued (in shares) | shares			867,194
Par value per share (in dollars per share) | $ / shares			$ 17.50
Gross proceeds from issuance of convertible preferred units | $			$ 15,200
Net proceeds from issuance of convertible preferred units | $			14,200
Issuance costs of financing | $			$ 1,000

Subsequent Events - Future Mini

Subsequent Events - Future Minimum Lease Payments (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Jan. 31, 2020	Dec. 31, 2019
Subsequent Event [Line Items]
2021	$ 765
2022	1,044		$ 1,044
2023	661		661
2024	187		187
Total minimum lease payments	$ 2,657		$ 2,907
Subsequent Event
Subsequent Event [Line Items]
2021		$ 2,018
2022		2,078
2023		2,140
2024		2,205
2025		2,271
Thereafter		12,419
Total minimum lease payments		$ 23,131