0001725160-24-000158 | 10-Q | XBRL Viewer | Zentalis Pharmaceuticals INC

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Interim Unaudited Financial Statements	6 Months Ended
Interim Unaudited Financial Statements	Jun. 30, 2024
Accounting Policies [Abstract]
Interim Unaudited Financial Statements	Interim Unaudited Financial Statements Basis of Presentation The accompanying interim unaudited condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”) and with the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) related to a quarterly report on Form 10-Q. The year-end condensed consolidated balance sheet data was derived from the Company’s audited financial statements but do not include all disclosures required by U.S. GAAP. These interim unaudited condensed consolidated financial statements and notes thereto should be read in conjunction with the Company’s audited financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023, filed with the SEC on February 27, 2024. The unaudited financial information for the interim periods presented herein reflects all adjustments which, in the opinion of management, are necessary for a fair presentation of the financial condition and results of operation for the periods presented, with such adjustments consisting only of normal recurring adjustments. Certain reclassifications have been made to the prior period condensed consolidated balance sheet to conform to the current period presentation. The accompanying interim unaudited condensed consolidated financial statements include our wholly-owned subsidiaries and Kalyra Pharmaceuticals, Inc. (“Kalyra”), a variable interest entity (“VIE”) for which we were the primary beneficiary until Kalyra was dissolved in January 2024 (See Note 4 - Business Combinations for additional information). All intercompany transactions and balances have been eliminated in consolidation. Following the dissolution of Kalyra, we no longer have an interest in any VIEs. 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. Goodwill 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 research and development (“IPR&D”). 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 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 proceed to compare the estimated fair values of the reporting units with the carrying values, including goodwill. If the carrying amounts of the reporting units exceed the fair values, we record an impairment loss based on the difference. We completed our most recent annual evaluation for impairment for goodwill as of June 30, 2024 using the qualitative and quantitative assessment and determined that no impairment existed, and no charges were recorded. Significant Accounting Policies During the six months ended June 30, 2024 we adopted the following significant accounting policies not previously reported in the Company’s significant accounting policies as described in its Annual Report on Form 10-K for the fiscal year ended December 31, 2023. Investments in equity securities We carry investments in equity securities at fair value and record the changes in fair values in the Consolidated Statement of Operations as a component of Investment and other income, net.

Net Income (Loss) Per Common Share

6 Months Ended

Jun. 30, 2024

Earnings Per Share [Abstract]

Net Income (Loss) Per Common Share

Basic and diluted net income (loss) per common share were calculated as follows (in thousands except per share amounts):


	Three Months Ended June 30,				Six Months Ended June 30,
	2024		2023			2024		2023
Numerator:
Net income (loss) attributable to Zentalis	$	(88,277)	$	(112,527)		$	(78,209)	$	(175,746)
Denominator:
Weighted average number of common shares outstanding, basic and diluted	71,040		60,790			70,969		60,038





Net loss per common share	$	(1.24)	$	(1.85)		$	(1.10)	$	(2.93)

Our potential and dilutive securities, which include outstanding stock options, unvested RSAs and unvested RSUs have been excluded from the computation of diluted net loss per common share as the effect would be anti-dilutive.

The following common stock equivalents have been excluded from the calculations of diluted net income (loss) per common share because their inclusion would be antidilutive (in thousands).


	June 30,
	2024	2023
Outstanding stock options	11,488	10,085
Unvested RSAs	—	42
Unvested RSUs	2,403	1,499
	13,891	11,626

Property and Equipment, net - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Property, Plant and Equipment [Abstract]
Depreciation and amortization	$ 327	$ 344	$ 651	$ 704

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Current assets
Cash and cash equivalents	$ 36,976	$ 28,038
Marketable securities, available-for-sale	389,409	454,881
Prepaid expenses and other current assets	13,231	13,799
Total current assets	439,616	496,718
Property and equipment, net	5,337	5,819
Operating lease right-of-use assets	33,474	35,916
Prepaid expenses and other assets	6,836	6,818
Goodwill	3,736	3,736
Restricted cash	2,681	2,681
Total assets	491,680	551,688
Current liabilities
Accounts payable	20,440	14,926
Accrued expenses	46,252	54,441
Total current liabilities	66,692	69,367
Long-term lease liability	41,318	43,150
Other long-term liabilities	1,089	1,780
Total liabilities	109,099	114,297
Commitments and contingencies
EQUITY
Preferred stock, $0.001 par value; 10,000,000 shares authorized; no shares issued and outstanding at June 30, 2024 and December 31, 2023	0	0
Common stock, $0.001 par value; 250,000,000 shares authorized; 71,106,719 and 70,765,554 shares issued and outstanding at June 30, 2024 and December 31, 2023, respectively	71	70
Additional paid-in capital	1,349,135	1,323,576
Accumulated other comprehensive income	140	2,194
Accumulated deficit	(966,765)	(888,556)
Total stockholders’ equity	382,581	437,284
Noncontrolling interests	0	107
Total equity	382,581	437,391
Total liabilities and stockholders’ equity	$ 491,680	$ 551,688

Insider Trading Arrangements	3 Months Ended	6 Months Ended
Insider Trading Arrangements	Jun. 30, 2024 shares	Jun. 30, 2024 shares
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Terminated	false
Diana Hausman, M.D [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		On May 2, 2024, a Rule 10b5-1 trading arrangement intended to satisfy the affirmative defense of Rule 10b5-1(c), originally adopted on December 5, 2023 by Diana Hausman, M.D., the Company’s former Chief Medical Officer, for the sale of up to 13,244 shares of the Company’s common stock until May 31, 2025, was terminated.
Name	Diana Hausman, M.D
Title	Chief Medical Officer
Rule 10b5-1 Arrangement Terminated	true
Termination Date	May 2, 2024
Aggregate Available	13,244	13,244
Jan Skvarka [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		On June 17, 2024, a Rule 10b5-1 trading arrangement intended to satisfy the affirmative defense of Rule 10b5-1(c), originally adopted on November 16, 2023 by Jan Skvarka, a member of the Company’s Board of Directors, for the sale of up to 11,368 shares of the Company’s common stock until December 31, 2024, was terminated.
Name	Jan Skvarka
Title	Board of Directors
Rule 10b5-1 Arrangement Terminated	true
Termination Date	June 17, 2024
Aggregate Available	11,368	11,368

Significant Transactions	6 Months Ended
Significant Transactions	Jun. 30, 2024
Equity Method Investments and Joint Ventures [Abstract]
Significant Transactions	Significant Transactions Immunome In January 2024, Immunome, Inc. (“Immunome”) and Zentalis Pharmaceuticals, Inc. entered into an exclusive, worldwide license agreement under which Immunome licensed from Zentalis ZPC-21, a preclinical ROR1 antibody-drug conjugate (“ADC”) and stock issuance agreement (the “Stock Issuance Agreement”). The upfront consideration from Immunome amounted to $15.0 million in cash and $20.0 million in shares of Immunome common stock, with the shares valued at the trailing 30-day volume-weighted average price. On the date of execution of the transaction, the Immunome common stock was valued at $25.6 million. The performance obligation associated with this upfront payment was met as of March 31, 2024, and $40.6 million, comprised of cash and the fair value of the Immunome stock on the date of execution of the transaction, was recognized as license revenue, within the condensed consolidated statement of operations. The stock acquired was recorded at fair value on the date of acquisition, within marketable securities, available for sale on the condensed consolidated balance sheet. Pursuant to the terms of the Stock Issuance Agreement, Zentalis agreed to hold and not sell greater than 50% of the shares until the six-month anniversary of the closing date, subject to certain exceptions. Changes in fair value of the Immunome stock for the three and six months ended June 30, 2024 amounted to a reduction of $28.9 million and an increase of $2.3 million, respectively, recorded as a component of investment and other income, net within the condensed consolidated statement of operations. There were no disposals of the acquired stock during the three and six months ended June 30, 2024.

Business Combinations (Tables)

6 Months Ended

Jun. 30, 2024

Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]

Schedule of Reconciliation of Equity Attributable to Noncontrolling Interest

The following is a reconciliation of equity (net assets) attributable to the noncontrolling interest (in thousands):


	June 30,		December 31,
	2024		2023
Noncontrolling interest at beginning of period	$	107	$	221
Net loss attributable to noncontrolling interest	(28)		(114)

Deconsolidation of Kalyra	(79)		—

Noncontrolling interest at end of period	$	—	$	107

Condensed Consolidated Statements of Stockholders’ Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Noncontrolling Interests
Beginning balance (in shares) at Dec. 31, 2022		59,280,000
Beginning balance at Dec. 31, 2022	$ 434,024	$ 59	$ 1,031,462	$ (1,353)	$ (596,365)	$ 221
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	27,075		27,075
Other comprehensive (loss) income	1,015			1,015
Issuance of common stock in connection with an equity offering, net of underwriting discounts, commissions and offering costs (in shares)		11,033,000
Issuance of common stock in connection with an equity offering, net of underwriting discounts, commissions and offering costs	235,680	$ 11	235,669
Issuance of common stock in connection with restricted stock unit vesting (in shares)		218,000
Issuance of common stock upon exercise of options, net (in shares)		51,000
Issuance of common stock upon exercise of options, net	941		941
Shares issued under employee stock purchase plan (in shares)		25,000
Shares issued under employee stock purchase plan	373		373
Cancellation of restricted stock awards (in shares)		(3,000)
Net loss attributable to non-controlling interest	(80)					(80)
Net loss attributable to Zentalis	(175,746)				(175,746)
Ending balance (in shares) at Jun. 30, 2023		70,604,000
Ending balance at Jun. 30, 2023	523,282	$ 70	1,295,520	(338)	(772,111)	141
Beginning balance (in shares) at Dec. 31, 2022		59,280,000
Beginning balance at Dec. 31, 2022	$ 434,024	$ 59	1,031,462	(1,353)	(596,365)	221
Ending balance (in shares) at Dec. 31, 2023	70,765,554	70,767,000
Ending balance at Dec. 31, 2023	$ 437,391	$ 70	1,323,576	2,194	(888,556)	107
Beginning balance (in shares) at Mar. 31, 2023		59,442,000
Beginning balance at Mar. 31, 2023	385,665	$ 59	1,045,568	(556)	(659,584)	178
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	13,342		13,342
Other comprehensive (loss) income	218			218
Issuance of common stock in connection with an equity offering, net of underwriting discounts, commissions and offering costs (in shares)		11,033,000
Issuance of common stock in connection with an equity offering, net of underwriting discounts, commissions and offering costs	235,680	$ 11	235,669
Issuance of common stock in connection with restricted stock unit vesting (in shares)		79,000
Issuance of common stock upon exercise of options, net (in shares)		51,000
Issuance of common stock upon exercise of options, net	941		941
Cancellation of restricted stock awards (in shares)		(1,000)
Net loss attributable to non-controlling interest	(37)					(37)
Net loss attributable to Zentalis	(112,527)				(112,527)
Ending balance (in shares) at Jun. 30, 2023		70,604,000
Ending balance at Jun. 30, 2023	$ 523,282	$ 70	1,295,520	(338)	(772,111)	141
Beginning balance (in shares) at Dec. 31, 2023	70,765,554	70,767,000
Beginning balance at Dec. 31, 2023	$ 437,391	$ 70	1,323,576	2,194	(888,556)	107
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	25,544		25,544
Other comprehensive (loss) income	(2,054)			(2,054)
Issuance and withholding of common stock in connection with restricted stock unit vesting, net (in shares)		322,000
Issuance and withholding of common stock in connection with restricted stock unit vesting, net	$ (240)	$ 1	(241)
Issuance of common stock in connection with restricted stock unit vesting (in shares)	1,000
Deconsolidation of Kalyra	$ (79)					(79)
Issuance of common stock upon exercise of options, net (in shares)	1,000
Issuance of common stock upon exercise of options, net	$ 8		8
Shares issued under employee stock purchase plan (in shares)		18,000
Shares issued under employee stock purchase plan	248		248
Net loss attributable to non-controlling interest	(28)					(28)
Net loss attributable to Zentalis	$ (78,209)				(78,209)
Ending balance (in shares) at Jun. 30, 2024	71,106,719	71,107,000
Ending balance at Jun. 30, 2024	$ 382,581	$ 71	1,349,135	140	(966,765)	0
Beginning balance (in shares) at Mar. 31, 2024		71,013,000
Beginning balance at Mar. 31, 2024	458,771	$ 70	1,336,416	773	(878,488)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	12,711		12,711
Other comprehensive (loss) income	(633)			(633)
Issuance and withholding of common stock in connection with restricted stock unit vesting, net (in shares)		94,000
Issuance and withholding of common stock in connection with restricted stock unit vesting, net	1	$ 1
Issuance of common stock upon exercise of options, net	8		8
Net loss attributable to non-controlling interest	0
Net loss attributable to Zentalis	$ (88,277)				(88,277)
Ending balance (in shares) at Jun. 30, 2024	71,106,719	71,107,000
Ending balance at Jun. 30, 2024	$ 382,581	$ 71	$ 1,349,135	$ 140	$ (966,765)	$ 0

Fair Value Measurement

6 Months Ended

Jun. 30, 2024

Fair Value Disclosures [Abstract]

Fair Value Measurement

Available-for-sale marketable debt securities consisted of the following (in thousands):


	June 30, 2024
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Commercial paper	$	15,337	$	1	$	(2)	$	15,336
Corporate debt securities	251,641		246		(76)		251,811
US government agencies	40,940		1		(10)		40,931
US treasury securities	53,539		1		(22)		53,518

	$	361,457	$	249	$	(110)	$	361,596


	December 31, 2023
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Commercial paper	$	75,227	$	60	$	(15)	$	75,272
Corporate debt securities	229,896		2,036		—		231,932
US government agencies	83,025		100		(78)		83,047
US treasury securities	64,538		103		(11)		64,630
	$	452,686	$	2,299	$	(104)	$	454,881

As of June 30, 2024, twenty-two of our available-for-sale debt securities with a fair market value of $193.9 million were in a gross unrealized loss position of $0.1 million. Twenty-one have been in a gross unrealized loss position of $0.1 million for less than one year and one has been in a gross unrealized loss position of less than $0.1 million for more than one year. When evaluating an investment for impairment, we review factors such as the severity of the impairment, changes in underlying credit ratings, forecasted recovery, our intent to sell or the likelihood that we would be required to sell the investment before its anticipated recovery in market value and the probability that the scheduled cash payments will continue to be made. Based on our review of these marketable securities, we believe none of the unrealized loss is as a result of a credit loss as of June 30, 2024, because we do not intend to sell these securities, and it is not more-likely-than-not that we will be required to sell these securities before the recovery of their amortized cost basis.

Contractual maturities of available-for-sale debt securities are as follows (in thousands):



	June 30, 2024		December 31, 2023
	Estimated Fair Value
Due within one year	$	272,370	$	267,336
After one but within five years	89,226		187,545
	$	361,596	$	454,881

The Company had $0.5 million in contingent consideration liabilities as of June 30, 2024 related to the agreement to terminate its Collaboration and License Agreements with Zentera. The contingent consideration balance is limited to one potential milestone payment measured at fair value. The fair value of the contingent consideration is estimated based on the monetary value of the milestone discounted for the probability of achieving the milestone and a present value factor based on the timing of when the milestone is expected to be achieved. The value for the contingent consideration balance is based on significant inputs not observable in the market which represents Level 3 measurement within the fair value hierarchy.

The following table summarizes the financial assets and liabilities that are measured on a recurring basis at fair value as of June 30, 2024 and December 31, 2023 (in thousands):


	June 30, 2024
	Level 1		Level 2		Level 3		Total estimated fair value
Financial assets:
Cash equivalents:
Money market funds	$	11,256	$	—	$	—	$	11,256


Total cash equivalents:	11,256		—		—		11,256

Available-for-sale marketable securities:
Commercial paper	—		15,336		—		15,336
Corporate debt securities	—		251,811		—		251,811
US government agencies	—		40,931		—		40,931
US treasury securities	—		53,518		—		53,518
Immunome equity securities	27,813		—		—		27,813
Total available-for-sale marketable securities:	27,813		361,596		—		389,409

Total assets measured at fair value	$	39,069	$	361,596	$	—	$	400,665
Financial liabilities:
Contingent consideration	—		—		500		500
Total financial liabilities	$	—	$	—	$	500	$	500


	December 31, 2023
	Level 1		Level 2		Level 3		Total estimated fair value
Financial assets:
Cash equivalents:
Money market funds	$	4,755	$	—	$	—	$	4,755

Total cash equivalents:	4,755		—		—		4,755

Available-for-sale marketable securities:
Commercial paper	—		75,272		—		75,272
Corporate debt securities	—		231,932		—		231,932
US government agencies	—		83,047		—		83,047
US treasury securities	—		64,630		—		64,630
Total available-for-sale marketable securities:	—		454,881		—		454,881

Total assets measured at fair value	$	4,755	$	454,881	$	—	$	459,636
Financial liabilities:
Contingent consideration	—		—		500		500
Total financial liabilities	$	—	$	—	$	500	$	500

The following significant unobservable inputs were used in the valuation of the contingent consideration payable to Zentera pursuant to the Termination Agreement at June 30, 2024:

Contingent Consideration Liability

Fair Value

as of

June 30, 2024

Valuation Technique

Unobservable Input

Range

(in thousands)

Milestone payment

500

Discounted cash flow

Likelihood of occurrence

1.0% - 2.4%

Discount rate

40%

Expected term

Perpetuity

The following table reflects the activity for the Company’s contingent consideration, measured at fair value using Level 3 inputs (in thousands):


Contingent consideration at December 31, 2023	500

Changes in the fair value of contingent consideration	—
Contingent consideration at June 30, 2024	$	500

There were no transfers between Level 1 and Level 2 of the fair value hierarchy during the six months ended June 30, 2024. We had one instrument that was classified within Level 3 as of June 30, 2024. As of June 30, 2024 and December 31, 2023, no material fair value adjustments were required for non-financial assets and liabilities.

Commitments and Contingencies - Narrative (Details) $ in Millions	1 Months Ended		6 Months Ended
	Jun. 30, 2024 USD ($)	Dec. 31, 2023 ft²	Jun. 30, 2024 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease, weighted-average remaining lease term (in years)	8 years 3 months 18 days		8 years 3 months 18 days
Sublease income			$ 0.7
New York City \| Building
Lessee, Lease, Description [Line Items]
Area of leased space (in square feet) \| ft²		4,115
Gain on lease termination	$ 0.5

Cover - shares	6 Months Ended
Cover - shares	Jun. 30, 2024	Aug. 07, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2024
Document Transition Report	false
Entity File Number	001-39263
Entity Registrant Name	Zentalis Pharmaceuticals, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-3607803
Entity Address, Address Line One	10275 Science Center Dr.
Entity Address, Address Line Two	Suite 200
Entity Address, City or Town	San Diego,
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	263-4333
Title of 12(b) Security	Common Stock,$0.001 par value per share
Trading Symbol	ZNTL
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		71,107,967
Entity Central Index Key	0001725160
Amendment Flag	false
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024

Stockholders’ Equity - Fair Value Assumptions for Stock Options (Details) - Stock Options	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected volatility, minimum	75.30%	77.50%
Expected volatility, maximum	78.40%	80.80%
Risk-free interest rate, minimum	3.80%	3.40%
Risk-free interest rate, maximum	4.60%	4.20%
Expected dividend yield	0.00%	0.00%
Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Average expected term (in years)	5 years 10 months 24 days	5 years 6 months
Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Average expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days

Net Income (Loss) Per Common Share - Antidilutive Securities (Details) - shares shares in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per unit (in shares)	13,891	11,626
Outstanding stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per unit (in shares)	11,488	10,085
Unvested RSAs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per unit (in shares)	0	42
Unvested RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per unit (in shares)	2,403	1,499

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Pay vs Performance Disclosure
Net loss attributable to Zentalis	$ (88,277)	$ (112,527)	$ (78,209)	$ (175,746)

Significant Transactions (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended			6 Months Ended
Significant Transactions (Details) - USD ($) $ in Thousands	Jan. 31, 2024	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Schedule of Equity Method Investments [Line Items]
License Revenue		$ 0		$ 0	$ 40,560	$ 0
Fair value of the Immunome stock, increase (reduction)		(22,863)		$ 4,451	12,085	$ 8,560
Immunome, Inc
Schedule of Equity Method Investments [Line Items]
Upfront consideration, cash	$ 15,000
Upfront consideration, value of shares	$ 20,000
Trailing volume-weighted average price period (in days)	30 days
Value of common stock	$ 25,600
License Revenue			$ 40,600
Percent of shares to be hold and not sold	50.00%
Anniversary term of shares to be held and not sold (in months)	6 months
Fair value of the Immunome stock, increase (reduction)		$ (28,900)			$ 2,300

Fair Value Measurement - Measurement Inputs for Contingent Consideration Liability (Details) $ in Thousands	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration	$ 500	$ 500
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration	$ 500	$ 500
Level 3 \| Discounted cash flow \| Likelihood of occurrence \| Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.010
Level 3 \| Discounted cash flow \| Likelihood of occurrence \| Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.024
Level 3 \| Milestone payment \| Discount rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.40
Level 3 \| Milestone payment \| Discounted cash flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration	$ 500

Prepaid Expenses and Other Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid insurance	$ 778	$ 747
Prepaid software licenses and maintenance	566	691
Foreign R&D credit refund	821	500
Prepaid research and development expenses	12,567	13,640
Interest receivable	3,279	3,337
Sublease assets	819	1,471
Other prepaid expenses	1,237	231
Total prepaid expenses and other assets	20,067	20,617
Less long-term portion	6,836	6,818
Total prepaid expenses and other assets, current	$ 13,231	$ 13,799

Fair Value Measurement - Activity for Contingent Consideration (Details) - Contingent Consideration Liability $ in Thousands	6 Months Ended
	Jun. 30, 2024 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent consideration, beginning balance	$ 500
Changes in the fair value of contingent consideration	0
Contingent consideration, ending balance	$ 500

Fair Value Measurement - Fair Value of Assets and Liabilities Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Financial assets:
Cash equivalents	$ 11,256	$ 4,755
Marketable securities, available-for-sale	361,596	454,881
Immunome equity securities	27,813
Total available-for-sale marketable securities:	389,409	454,881
Total assets measured at fair value	400,665	459,636
Financial liabilities:
Contingent consideration	500	500
Total financial liabilities	500	500
Level 1
Financial assets:
Cash equivalents	11,256	4,755
Immunome equity securities	27,813
Total available-for-sale marketable securities:	27,813	0
Total assets measured at fair value	39,069	4,755
Financial liabilities:
Contingent consideration	0	0
Total financial liabilities	0	0
Level 2
Financial assets:
Cash equivalents	0	0
Immunome equity securities	0
Total available-for-sale marketable securities:	361,596	454,881
Total assets measured at fair value	361,596	454,881
Financial liabilities:
Contingent consideration	0	0
Total financial liabilities	0	0
Level 3
Financial assets:
Cash equivalents	0	0
Immunome equity securities	0
Total available-for-sale marketable securities:	0	0
Total assets measured at fair value	0	0
Financial liabilities:
Contingent consideration	500	500
Total financial liabilities	500	500
Commercial paper
Financial assets:
Marketable securities, available-for-sale	15,336	75,272
Commercial paper \| Level 1
Financial assets:
Marketable securities, available-for-sale	0	0
Commercial paper \| Level 2
Financial assets:
Marketable securities, available-for-sale	15,336	75,272
Commercial paper \| Level 3
Financial assets:
Marketable securities, available-for-sale	0	0
Corporate debt securities
Financial assets:
Marketable securities, available-for-sale	251,811	231,932
Corporate debt securities \| Level 1
Financial assets:
Marketable securities, available-for-sale	0	0
Corporate debt securities \| Level 2
Financial assets:
Marketable securities, available-for-sale	251,811	231,932
Corporate debt securities \| Level 3
Financial assets:
Marketable securities, available-for-sale	0	0
US government agencies
Financial assets:
Marketable securities, available-for-sale	40,931	83,047
US government agencies \| Level 1
Financial assets:
Marketable securities, available-for-sale	0	0
US government agencies \| Level 2
Financial assets:
Marketable securities, available-for-sale	40,931	83,047
US government agencies \| Level 3
Financial assets:
Marketable securities, available-for-sale	0	0
US treasury securities
Financial assets:
Marketable securities, available-for-sale	53,518	64,630
US treasury securities \| Level 1
Financial assets:
Marketable securities, available-for-sale	0	0
US treasury securities \| Level 2
Financial assets:
Marketable securities, available-for-sale	53,518	64,630
US treasury securities \| Level 3
Financial assets:
Marketable securities, available-for-sale	0	0
Money market funds
Financial assets:
Cash equivalents	11,256	4,755
Money market funds \| Level 1
Financial assets:
Cash equivalents	11,256	4,755
Money market funds \| Level 2
Financial assets:
Cash equivalents	0	0
Money market funds \| Level 3
Financial assets:
Cash equivalents	$ 0	$ 0

Fair Value Measurement - Contractual Maturities of Available-for-sale Debt Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Due within one year	$ 272,370	$ 267,336
After one but within five years	89,226	187,545
Total	$ 361,596	$ 454,881

Stockholders’ Equity - Fair Value Assumptions for ESPP (Details) - Employee Stock Purchase Plan	6 Months Ended
	Jun. 30, 2024
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Volatility	107.30%
Expected term (years)	6 months
Risk free rate	5.40%
Expected dividend yield	0.00%

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Jun. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	250,000,000	250,000,000
Common stock issued (in shares)	71,106,719	70,765,554
Common stock outstanding (in shares)	71,106,719	70,765,554

Fair Value Measurement - Components of Available-for-sale Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 361,457	$ 452,686
Gross Unrealized Gains	249	2,299
Gross Unrealized Losses	(110)	(104)
Estimated Fair Value	361,596	454,881
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	15,337	75,227
Gross Unrealized Gains	1	60
Gross Unrealized Losses	(2)	(15)
Estimated Fair Value	15,336	75,272
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	251,641	229,896
Gross Unrealized Gains	246	2,036
Gross Unrealized Losses	(76)	0
Estimated Fair Value	251,811	231,932
US government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	40,940	83,025
Gross Unrealized Gains	1	100
Gross Unrealized Losses	(10)	(78)
Estimated Fair Value	40,931	83,047
US treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	53,539	64,538
Gross Unrealized Gains	1	103
Gross Unrealized Losses	(22)	(11)
Estimated Fair Value	$ 53,518	$ 64,630

Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued research and development expenses	$ 36,145	$ 36,261
Accrued employee expenses	6,471	14,477
Accrued general and administrative expenses	612	1,032
Lease liability	2,709	2,623
Contingent consideration	500	500
Income Taxes payable	425	281
Accrued legal expenses	479	1,047
Total accrued expenses	47,341	56,221
Less long-term portion	1,089	1,780
Total accrued expenses	$ 46,252	$ 54,441

Business Combinations - Narrative (Details) - USD ($)	Dec. 21, 2017	Jun. 30, 2024	Dec. 31, 2023
Variable Interest Entity [Line Items]
Assets		$ 491,680,000	$ 551,688,000
Liabilities		109,099,000	114,297,000
Kalyra Pharmaceuticals, Inc.
Variable Interest Entity [Line Items]
Cash payments to acquire interest	$ 4,500,000
Ownership percentage	25.00%
Kalyra Pharmaceuticals, Inc. \| Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Assets		0	0
Liabilities		$ 0	$ 0

Stockholders’ Equity - Narrative (Details) - USD ($)		1 Months Ended	6 Months Ended
Stockholders’ Equity - Narrative (Details) - USD ($)	Jun. 15, 2023	Apr. 30, 2020	Jun. 30, 2024	Jun. 30, 2023	Jul. 31, 2022
Class of Stock [Line Items]
Issuance of common stock upon exercise of options, net (less than) (in shares)			1,000
Shares issued upon vesting of certain RSAs (less than) (in shares)			1,000
Stock Options
Class of Stock [Line Items]
Generally expected vesting term of the option contract (in years)			10 years
Expected dividend yield			0.00%	0.00%
Options outstanding (in shares)			11,500,000
Employee Stock Purchase Plan
Class of Stock [Line Items]
Number of shares reserved for future issuance (in shares)			1,894,676
Expected dividend yield			0.00%
ESPP maximum percent of compensation to contribute			20.00%
Maximum contribution amount			$ 25,000
ESPP purchase price of common stock, percent of market price			85.00%
Offering period (in months)			6 months
RSUs
Class of Stock [Line Items]
Non-option equity instruments, outstanding (in shares)			2,400,000
The 2020 Plan
Class of Stock [Line Items]
Non-option equity instruments, outstanding (in shares)			11,480,796
Number of shares available for future grants (in shares)			2,811,551
2022 Inducement Plan
Class of Stock [Line Items]
Non-option equity instruments, outstanding (in shares)			2,409,816
Number of shares available for future grants (in shares)			840,184
Number of shares reserved for future issuance (in shares)					3,275,000
Follow On Offering
Class of Stock [Line Items]
Gross proceeds from issuance of common stock	$ 250,000,000.0
Expenses and fees from the issuance of common stock	$ 14,300,000
Common Stock \| The 2020 Plan
Class of Stock [Line Items]
Shares authorized to be issued under plan (in shares)		5,600,000
Percent of common stock outstanding used as threshold to calculate shares available for issuance		5.00%
Common Stock \| Follow On Offering
Class of Stock [Line Items]
Number of shares issued and sold (in shares)	11,032,656
Share price (in dollars per share)	$ 22.66
Common Class B \| The 2020 Plan \| Maximum
Class of Stock [Line Items]
Shares authorized to be issued under plan (in shares)		1,250,000

Organization and Business	6 Months Ended
Organization and Business	Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Business	Organization and Business Organization Zentalis Pharmaceuticals, Inc. (“Zentalis,” “We” or the “Company”) is a clinical-stage biopharmaceutical company discovering and developing small molecule therapeutics targeting fundamental biological pathways of cancers. The Company’s lead product candidate, azenosertib (ZN-c3), is a potentially first-in-class and best-in-class WEE1 inhibitor for advanced solid tumors and hematologic malignancies. The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. All of the Company’s tangible assets are held in the United States. 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 June 30, 2024 are issued.

Fair Value Measurement - Narrative (Details) $ in Thousands	Jun. 30, 2024 USD ($) security potential_milestone_payment	Dec. 31, 2023 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Number of available-for-sale securities in unrealized loss position \| security	22
Debt securities fair market value	$ 193,900
Fair market value of available-for-sale securities in unrealized loss position	$ 100
Number of available-for-sale securities in unrealized loss position for less than one year \| security	21
Gross unrealized loss position for less than one year	$ 100
Number of available-for-sale securities in unrealized loss position for more than one year \| security	1
Gross unrealized loss position for more than one year (less than)	$ 100
Contingent consideration	500	$ 500
Zentera \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration	$ 500
Number of potential milestone payments \| potential_milestone_payment	1

Stockholders’ Equity - Unrecognized Compensation Cost (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2024 USD ($)
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized expense, stock options	$ 80,212
Remaining Weighted-Average Recognition Period (years)	2 years 7 months 20 days
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized expense, other than stock options	$ 28,793
Remaining Weighted-Average Recognition Period (years)	3 years 3 days
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized expense, other than stock options	$ 140
Remaining Weighted-Average Recognition Period (years)	3 months

Property and Equipment, net - Summary (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Subtotal	$ 8,973	$ 8,967
Accumulated depreciation and amortization	(3,636)	(3,148)
Property and equipment, net	5,337	5,819
Lab equipment
Property, Plant and Equipment [Line Items]
Subtotal	3,382	3,069
Leasehold improvements
Property, Plant and Equipment [Line Items]
Subtotal	4,168	4,235
Office equipment and furniture
Property, Plant and Equipment [Line Items]
Subtotal	1,280	1,340
Computer equipment
Property, Plant and Equipment [Line Items]
Subtotal	143	150
Construction in progress
Property, Plant and Equipment [Line Items]
Subtotal	$ 0	$ 173

Commitments and Contingencies - Future Minimum Lease Payments (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
2024 (remaining)	$ 3,330
2025	6,799
2026	7,278
2027	7,451
2028	7,760
Thereafter	31,019
Total minimum lease payments:	63,637
Less: imputed interest	(19,610)
Total operating lease liabilities	44,027
Less: current portion	(2,709)	$ (2,623)
Lease liability, net of current portion	$ 41,318	$ 43,150