BioAtla (BCAB) 10-Q 11 May 23 2023 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2023	May 10, 2023
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Mar. 31, 2023
Document Fiscal Year Focus	2023
Entity File Number	001-39787
Entity Registrant Name	BIOATLA, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	85-1922320
Entity Address, Address Line One	11085 Torreyana Road
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	558-0708
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Trading Symbol	BCAB
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Central Index Key	0001826892
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	Q1
Common Class B
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		0
Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		47,667,516

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 192,687	$ 215,507
Prepaid expenses and other current assets	7,030	4,924
Total current assets	199,717	220,431
Property and equipment, net	2,485	2,728
Operating lease right-of-use asset, net	2,196	2,423
Other assets	154	154
Total assets	204,552	225,736
Current liabilities:
Accounts payable and accrued expenses	24,711	21,610
Operating lease liabilities	1,545	1,521
Total current liabilities	26,256	23,131
Operating lease liabilities, less current portion	2,063	2,460
Liability to licensor	19,806	19,806
Total liabilities	48,125	45,397
Commitments and contingencies (Note 5)
Stockholders’ equity:
Preferred stock, $0.0001 par value; 200,000,000 shares authorized at March 31, 2023 and December 31, 2022; 0 shares issued and outstanding at March 31, 2023 and December 31, 2022
Common stock value	5	5
Additional paid-in capital	476,683	473,135
Accumulated deficit	(320,261)	(292,801)
Total stockholders’ equity	156,427	180,339
Total liabilities and stockholders’ equity	204,552	225,736
Class B Common Stock
Stockholders’ equity:
Common stock value

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2023	Dec. 31, 2022
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	200,000,000	200,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	350,000,000	350,000,000
Common stock, shares issued (in shares)	47,637,321	46,336,166
Common stock, shares outstanding (in shares)	47,637,321	46,336,166
Class B Common Stock
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	15,368,569	15,368,569
Common stock, shares issued (in shares)	0	1,211,959
Common stock, shares outstanding (in shares)	0	1,211,959

Unaudited Condensed Consolidate

Unaudited Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating expenses:
Research and development expense	$ 21,697	$ 16,923
General and administrative expense	7,233	7,423
Total operating expenses	28,930	24,346
Loss from operations	(28,930)	(24,346)
Other income (expense):
Interest income	1,480	85
Other income (expense)	(10)	7
Total other income (expense)	1,470	92
Consolidated net loss and comprehensive loss	$ (27,460)	$ (24,254)
Net loss per common share, basic	$ (0.58)	$ (0.65)
Net loss per common share, diluted	$ (0.58)	$ (0.65)
Weighted-average shares of common stock outstanding, basic	47,578,418	37,322,360
Weighted-average shares of common stock outstanding, diluted	47,578,418	37,322,360

Unaudited Condensed Consolida_2

Unaudited Condensed Consolidated Statement of Stockholders' Equity - USD ($) $ in Thousands	Total	Class B Common Stock	Common Stock	Additional Paid-In Capital	Accumulate Deficit
Beginning balance at Dec. 31, 2021	$ 210,821		$ 4	$ 397,136	$ (186,319)
Beginning balance, share at Dec. 31, 2021		1,492,059	35,799,233
Stock-based compensation expense	3,632			3,632
Issuance of common stock under equity incentive plans, share			92,051
Taxes related to net share settlement of equity awards	(146)			(146)
Net loss	(24,254)				(24,254)
Ending balance at Mar. 31, 2022	190,053		$ 4	400,622	(210,573)
Ending balance, share at Mar. 31, 2022		1,492,059	35,891,284
Beginning balance at Dec. 31, 2022	180,339		$ 5	473,135	(292,801)
Beginning balance, share at Dec. 31, 2022		1,211,959	46,336,166
Stock-based compensation expense	3,614			3,614
Issuance of common stock under equity incentive plans, share			89,196
Taxes related to net share settlement of equity awards	(66)			(66)
Conversion of Class B common stock, shares		(1,211,959)	1,211,959
Net loss	(27,460)				(27,460)
Ending balance at Mar. 31, 2023	$ 156,427		$ 5	$ 476,683	$ (320,261)
Ending balance, share at Mar. 31, 2023		0	47,637,321

Unaudited Condensed Consolida_3

Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities
Net loss	$ (27,460)	$ (24,254)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	293	313
Stock-based compensation	3,614	3,632
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(2,106)	(2,278)
Accounts payable and accrued expenses	3,151	(2,433)
Right-of-use assets and lease liabilities, net	(146)	(116)
Net cash used in operating activities	(22,654)	(25,136)
Cash flows from investing activities
Purchases of property and equipment	(50)	(10)
Net cash used in investing activities	(50)	(10)
Cash flows from financing activities
Payments for taxes related to net settlement of equity awards	(116)	(405)
Net cash provided by (used in) financing activities	(116)	(405)
Net increase (decrease) in cash and cash equivalents	(22,820)	(25,551)
Cash and cash equivalents, beginning of period	215,507	244,979
Cash and cash equivalents, end of period	192,687	219,428
Supplemental disclosure of non-cash investing and financing activities
Property and equipment additions included in accounts payable and accrued expenses	0	23
TaxRelatedToNetSettlementOfEquityAwardsIncludedInAccountsPayableAndAccruedExpenses	$ 17	$ 32

Organization and Summary of Sig

Organization and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2023
Accounting Policies [Abstract]
Organization and Summary of Significant Accounting Policies	1. Organization and Summary of Significant Accounting Policies Organization BioAtla, LLC was formed in Delaware in March 2007 and was converted to a Delaware corporation in July 2020 and renamed BioAtla, Inc. (the “Company”). The Company has a proprietary platform for creating biologics, including its conditionally active biologics (“CAB” or “CABs”). CABs have been designed to be active only under certain conditions found in diseased tissue, while remaining inactive in normal tissue. The Company is currently in clinical development of its two lead CAB antibody drug conjugates targeting AXL and ROR2 receptors, its CAB immune-oncology antibody targeting CTLA-4 and its CAB BiSpecific targeting EpCAM. Basis of Presentation The unaudited condensed financial statements as of March 31, 2023, and for the three months ended March 31, 2023 and 2022, have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (“SEC”), and with accounting principles generally accepted in the United States (“GAAP”) applicable to interim financial statements. These unaudited condensed financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, consisting of only normal recurring accruals, which in the opinion of management are necessary to present fairly the Company’s financial position as of the interim date and results of operations for the interim periods presented. Interim results are not necessarily indicative of results for a full year or future periods. These unaudited condensed financial statements should be read in conjunction with the Company’s audited financial statements for the year ended December 31, 2022 , included in its Annual Report on Form 10-K filed with the SEC on March 23, 2023. Liquidity and Going Concern The Company has incurred cumulative operating losses and negative cash flows from operations since its inception and expects to continue to incur significant expenses and operating losses for the foreseeable future as it continues the development of its product candidates. As of March 31, 2023, the Company had an accumulated deficit of $ 320.3 million . The Company plans to continue to fund its losses from operations and capital funding needs through public or private equity or debt financings, or other sources. If the Company is not able to secure adequate additional funding, the Company may be forced to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, or suspend or curtail planned programs. Any of these actions could materially harm the Company’s business, results of operations and future prospects. Management is required to perform a two-step analysis of the Company’s ability to continue as a going concern. Management must first evaluate whether there are conditions and events that raise substantial doubt about the Company’s ability to continue as a going concern (Step 1). If management concludes that substantial doubt is raised, management is also required to consider whether its plans alleviate that doubt (Step 2). Management’s assessment included the preparation of cash flow forecasts resulting in management’s conclusion that there is not substantial doubt about the Company’s ability to continue as a going concern as its current cash and cash equivalents will be sufficient to fund the Company’s operations for a period of at least one year from the issuance date of these unaudited condensed financial statements. Use of Estimates The preparation of the Company’s condensed financial statements requires it to make estimates and assumptions that impact the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in the Company’s condensed financial statements and accompanying notes. The most significant estimates in the Company’s condensed financial statements relate to accruals for research and development costs, and equity-based compensation. These estimates and assumptions are based on current facts, historical experience and various other factors believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities and the recording of revenue and expenses that are not readily apparent from other sources. Actual results may differ materially and adversely from these estimates. To the extent there are material differences between the estimates and actual results, the Company’s future results of operations will be affected. Concentrations of Risk Financial instruments that potentially subject the Company to a significant concentration of credit risk consist primarily of cash and cash equivalents. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held. Stock-Based Compensation Stock-based compensation expense represents the grant date fair value of equity awards, consisting of stock options, restricted stock units (“RSUs”) and employee stock purchase plan rights, over the requisite service period of the awards (usually the vesting period) on a straight-line basis. The Company estimates the fair value of stock option grants and employee stock purchase plan rights using the Black-Scholes option pricing model. Prior to the Company’s IPO, the fair value of RSUs was based on the estimated fair value of the underlying common stock on the date of grant and, subsequent to the Company’s IPO, the fair value is based on the closing sales price of the Company’s common stock on the date of grant. Equity award forfeitures are recognized as they occur. Leases The Company determines if an arrangement is a lease at inception. An arrangement is or contains a lease if it conveys the right to control the use of an identified asset for a period of time in exchange for consideration. If a lease is identified, classification is determined at lease commencement. Operating lease liabilities are recognized at the present value of the future lease payments at the lease commencement date. The Company’s leases do not provide an implicit interest rate and therefore the Company estimates its incremental borrowing rate to discount lease payments. The incremental borrowing rate reflects the interest rate that the Company would have to pay to borrow on a collateralized basis an amount equal to the lease payments in a similar economic environment over a similar term. Operating lease right-of-use (“ROU”) assets are based on the corresponding lease liability adjusted for any lease payments made at or before commencement, initial direct costs, and lease incentives. Renewals or early terminations are not accounted for unless the Company is reasonably certain to exercise these options. Operating lease expense is recognized and the ROU asset is amortized on a straight-line basis over the lease term. Variable lease costs are not included in the calculation of the ROU asset and the related lease liability and are recognized as incurred. The Company has a single lease agreement with lease and non-lease components, which are accounted for as a single lease component. Payments for short-term leases, defined as leases with a term of twelve months or less, are expensed on a straight-line basis over the lease term. The Company does not currently have any short-term leases. Operating leases are included in operating lease right-of-use assets, operating lease liabilities, and operating lease liabilities, non-current on the Company’s balance sheets. The Company does not have any finance leases. Comprehensive Loss Comprehensive loss is defined as a change in equity during a period from transactions and other events and circumstances from non-owner sources. There have been no items qualifying as other comprehensive loss and, therefore, for all periods presented, the Company’s comprehensive loss was the same as its reported net loss. Net Loss Per Share Basic net loss per common share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares and dilutive common stock equivalents outstanding for the period determined using the treasury-stock method. Dilutive common stock equivalents are comprised of RSUs, common stock options outstanding under the Company’s stock option plan, and contingently issuable shares under the Company's ESPP plan. Potentially dilutive securities not included in the calculation of diluted net loss per common share because to do so would be anti-dilutive are as follows (in common stock equivalents): Three Months Ended 2023 2022 Common stock options 6,214,418 2,447,902 Restricted stock units 400,293 862,573 ESPP shares 122,565 31,346 Total 6,737,276 3,341,821 Recent Accounting Pronouncements There were no new accounting standards that had a material impact on the Company’s financial statements during the three or three months ended March 31, 2023, and there were no other new accounting standards or pronouncements that were issued but not yet effective as of March 31, 2023 that the Company expects to have a material impact on its financial statements.

Balance Sheet Details

Balance Sheet Details	3 Months Ended
	Mar. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Details	2. Balance Sheet Details Prepaid expenses and other current assets consist of the following (in thousands): March 31, December 31, Prepaid research and development $ 4,983 $ 4,385 Prepaid insurance 1,578 — Other prepaid expenses and current assets 469 539 Total $ 7,030 $ 4,924 Property and equipment consist of the following (in thousands): Useful life March 31, December 31, Furniture, fixtures and office equipment 3 - 7 $ 2,141 $ 2,140 Laboratory equipment 5 2,315 2,265 Leasehold improvements 2 - 3 3,687 3,687 8,143 8,092 Less accumulated depreciation and amortization ( 5,658 ) ( 5,364 ) Total $ 2,485 $ 2,728 Accounts payable and accrued expenses consist of the following (in thousands): March 31, December 31, Accounts payable $ 8,054 $ 4,231 Accrued compensation 1,290 3,451 Accrued research and development 14,660 12,649 Other accrued expenses 707 1,279 Total $ 24,711 $ 21,610

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The carrying amounts of the Company’s current financial assets and current financial liabilities are considered to be representative of their respective fair values because of the short-term nature of those instruments. As of March 31, 2023 and December 31, 2022 , the Company had no financial assets or liabilities measured at fair value on a recurring basis. The accounting guidance defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or non-recurring basis. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1: Observable inputs such as quoted prices in active markets. Level 2: Inputs, other than the quoted prices in active markets that are observable either directly or indirectly. Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. None of the Company’s non-financial assets and liabilities are recorded at fair value on a non-recurring basis. No transfers between levels have occurred during the periods presented.

Leases

Leases	3 Months Ended
	Mar. 31, 2023
Leases [Abstract]
Leases	4. Leases The Company has a single operating lease for its corporate headquarters and laboratory space in San Diego, California. The lease expires in July 2025 and the Company has an option to extend the term of the lease for an additional five years . Additionally, the lease includes certain rent abatement, rent escalations, tenant improvement allowances and additional charges for common area maintenance and other costs. The components of lease expense included in the Company’s statements of operations and loss include (in thousands): Three Months Ended March 31, 2023 2022 Operating lease expense $ 261 $ 261 Variable lease expense 147 132 Total lease expense, net $ 408 $ 393 Variable lease costs are primarily related to payments made to lessors for common area maintenance, property taxes, insurance, and other operating expenses. The Company did not have any short-term leases or finance leases for the three months ended March 31, 2023 and 2022, respectively. The weighted average remaining lease term and weighted average discount rate for operating leases were as follows: As of March 31, 2023 2022 Weighted average remaining lease term (in years) 2.25 3.25 Weighted average discount rate percentage 3.50 % 3.50 % Supplemental cash flow information related to leases under which the Company is the lessee was as follows (amounts in thousands): Three Months Ended March 31, 2023 2022 Cash paid for amounts included in the measurement of operating leases $ 407 $ 377 As of March 31, 2023, future minimum payments under the Company's non-cancelable operating lease under ASC 842 were as follows (in thousands): Operating Nine months ending December 31, 2023 $ 1,229 2024 1,685 2025 845 Thereafter — Total future lease payments 3,759 Less: imputed interest ( 151 ) Total operating lease liabilities $ 3,608

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	5. Commitments and Contingencies From time to time, the Company may be subject to various claims and suits arising in the ordinary course of business. The Company is not currently a party to any legal proceedings the outcome of which the Company believes, if determined adversely to the Company, would individually or in the aggregate have a material adverse effect on the Company’s business, operating results or financial condition.

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2023
Equity [Abstract]
Stockholders' Equity	6. Stockholders’ Equity 2020 Equity Incentive Plan The Company may grant awards of common stock under the 2020 Equity Incentive Plan (the "2020 Plan") to the Company’s employees, consultants and non-employee directors pursuant to option awards, stock appreciation rights awards, restricted stock awards, restricted stock unit awards, performance stock awards, performance stock unit awards and other stock-based awards. As of March 31, 2023 and December 31, 2022 , the total number of common shares authorized for issuance under the 2020 Plan was 9,196,970 and 7,658,509 , respective ly. On January 1st of each year, commencing with the first January 1st following the effective date of the 2020 Plan, the shares authorized for issuance under the 2020 Plan shall be increased by a number of shares equal to the lesser of 4 % of the total number of shares outstanding on the immediately preceding December 31st and such lesser number of shares determined by the Company’s board of directors. The maximum term of the options granted under the 2020 Plan is no more than ten years . Awards under the 2020 Plan generally vest at 25 % one year from the vesting commencement date and ratably each month thereafter for a period of 36 months , subject to continuous service. Stock-based compensation expense for the three months ended March 31, 2023 and 2022 has been reported in the condensed statements of operations and comprehensive loss as follows (in thousands): Three Months Ended 2023 2022 Research and development $ 1,451 $ 1,300 General and administrative 2,163 2,332 Total $ 3,614 $ 3,632 Restricted Stock Units The following table summarizes RSU activity under the 2020 Plan for the three months ended March 31, 2023: Number of Weighted - Average Outstanding at December 31, 2022 510,039 $ 18.00 Granted — $ — Vested ( 109,746 ) $ 18.00 Forfeited — $ — Outstanding at March 31, 2023 400,293 $ 18.00 As of March 31, 2023, total unrecognized stock-based compensation expense for RSUs was $ 7.2 million , which is expected to be recognized over a remaining weighted-average period of approximately 1.1 years . Stock Options The following table summarizes stock option activity under the 2020 Plan for the three months ended March 31, 2023: Number of Weighted - Average Weighted -Average Aggregate Balance at December 31, 2022 2,736,918 $ 13.82 8.82 $ 3,636,148 Granted 3,485,500 $ 3.84 Exercised — $ — Forfeited ( 8,000 ) $ 3.72 Expired — $ — Balance at March 31, 2023 6,214,418 $ 8.24 9.30 $ 37,544 Vested and expected to vest at March 31, 2023 6,214,418 $ 8.24 9.30 $ 37,544 Exercisable at March 31, 2023 929,919 $ 18.25 8.28 $ — As of March 31, 2023 , total unrecognized stock-based compensation cost for unvested common stock options was $ 22.4 million, which is expected to be recognized over a remaining weighted-average period of approximately 3.5 years. The weighted- average grant date fair value of stock options granted during the three months ended March 31, 2023 was $ 2.69 per share. The total fair value of options vested during the three months ended March 31, 2023 was $ 2.7 million. On February 26, 2023, the Compensation Committee of the Company’s Board of Directors approved a modification to the Company’s 2020 Equity Incentive Plan to allow vesting of RSUs or stock options, as applicable, subject to the grantee’s continued service to the Company and/or one of its subsidiaries as an employee, non-employee director, or independent contractor. Unvested RSUs totaling 139,730 shares and 574,244 unvested options which would have been forfeited under the original terms of the 2020 Equity Incentive plan will now continue to vest. The Company applied modification accounting to these awards which resulted in a decrease in fair value to these awards. The Company calculated compensation cost for the modified unvested awards of $ 416,000 related to the RSUs and $ 962,000 related to the options, and will recognize these amounts over the remaining requisite service periods. The modification also resulted in an increase to the term of 130,699 fully vested options for which $ 123,000 of incremental compensation cost was immediately recognized on the date of the modification. The assumptions used in the Black-Scholes option pricing model to determine the fair value of stock option grants were as follows: Three Months Ended 2023 2022 Expected volatility 77.3 % 76.4 % Risk-free interest rate 3.85 % 0.52 % Expected dividend yield 0.0 % 0.0 % Expected term 6.10 years 6.08 years Expected volatility. As the Company’s common stock does not have a significant trading history, the expected volatility assumption is based on volatilities of a peer group of similar companies whose share prices are publicly available. The peer group was developed based on companies in the biotechnology industry. Risk-free interest rate. The Company bases the risk-free interest rate assumption on the U.S. Treasury’s rates for U.S. Treasury zero-coupon bonds with maturities similar to those of the expected term of the award being valued. Expected dividend yield. The Company bases the expected dividend yield assumption on the fact that it has never paid cash dividends and has no present plans to pay cash dividends. Expected term. For employees, the expected term represents the period of time that options are expected to be outstanding. Because the Company has minimal historical exercise behavior, it determines the expected life assumption using the simplified method, which is an average of the contractual term of the option and its vesting period. For nonemployees, the expected term is generally the contractual term of the option. Employee Stock Purchase Plan The BioAtla, Inc. Employee Stock Purchase Plan (the “ESPP”) permits participants to purchase common stock through payroll deductions of up to 15 % of their eligible compensation. As of March 31, 2023 and December 31, 2022, a total of 1,737,098 shares and 1,229,148 shares, respectively, of common stock were authorized for issuance under the ESPP. The number of shares of common stock authorized for issuance will automatically increase on January 1 of each calendar year, from January 1, 2021 through January 1, 2030 by the least of (i) 1.0 % of the total number of common shares of our common stock outstanding on December 31 of the preceding calendar year (calculated on a fully diluted basis), (ii) 929,658 common shares or (iii) a number determined by the Company’s board of directors that is less than (i) and (ii). The Company did not issue any common shares under the ESPP during the three months ended March 31, 2023 and 2022. As of March 31, 2023, 1,578,352 shares o f common stock remained available for issuance under the ESPP. Stock-based compensation expense related to the ESPP for the three months ended March 31, 2023 and 2022 was immaterial. Common Stock Reserved for Future Issuance Common stock reserved for future issuance are as follows in common equivalent shares: March 31, December 31, Common stock options and restricted stock units issued and outstanding 6,614,711 3,246,957 Awards available for future issuance under the 2020 Plan 1,073,515 3,012,554 Awards available for future issuance under the ESPP 1,578,352 1,070,402 Total common stock reserved for future issuance 9,266,578 7,329,913

Collaboration, License and Opti

Collaboration, License and Option Agreements	3 Months Ended
	Mar. 31, 2023
Collaboration License And Option Agreements [Abstract]
Collaboration, License and Option Agreements	7. Collaboration, License and Option Agreements BeiGene In April 2019, the Company entered into a Global Co-Development and Collaboration agreement (the “BeiGene Collaboration”) with BeiGene, Ltd. and BeiGene Switzerland GmbH (collectively “BeiGene”), for the development, manufacturing and commercialization of the Company’s investigational CAB CTLA-4 antibody (BA3071). The BeiGene Collaboration was amended several times between 2019 and 2021 and the Company received a total of $ 25.0 million in non-refundable payments from BeiGene during that time. In November 2021, the BeiGene Collaboration was terminated, subject to survival of certain provisions, and BeiGene handed back rights to know-how and materials received under the amended BeiGene Collaboration. As a result, the Company is responsible for the global development and commercialization of BA3071. As consideration for this amendment, the Company agreed to pay BeiGene mid-single digit royalties on sales worldwide and on a limited basis will share in any upfront and milestone payments received through a sublicense of BA3071. The Company reclassified its then remaining $ 19.8 million of deferred revenue as a long-term liability which is expected to settle as licensing payments are made to BeiGene in accordance with the resulting amendment. In the event the license is terminated, the liability will be extinguished with no further payment to BeiGene. For the three months ended March 31, 2023 and 2022 , the Company did no t recognize any revenue related to the collaboration agreement with BeiGene. The Company had a $ 19.8 million liability to licensor as of March 31, 2023 and December 31, 2022. Service Contracts Prior to developing its own programs, the Company entered into various fixed price research service contracts. In connection with these service contracts, the Company may receive future milestone payments if certain clinical, regulatory and commercialization milestones are achieved. The Company is also eligible to receive royalties based on certain product sales. The Company did no t recognize any revenue related to its legacy service contracts during the three months ended March 31, 2023 or 2022. BMS Collaboration In January 2022, the Company and Bristol-Myers Squibb Company (“BMS”) entered into a clinical trial collaboration and supply agreement (the “BMS Agreement”). Under the terms of the BMS Agreement, BioAtla and BMS will collaborate on clinical trials of separate combination therapies using two of BioAtla’s Conditionally Active Biologic Antibody Drug Conjugates, BA3011 and BA3021, each in combination with Opdivo® (nivolumab), BMS’ proprietary anti-PD-1 monoclonal antibody product. The Company will serve as the study sponsor of the scheduled studies and will be responsible for costs associated with the trial execution. BMS will provide Opdivo® clinical drug supply at no cost for the combination study trials. After the completion of the combination therapy trials, the Company is obligated to provide BMS with a final report of the data resulting from the trial. The BMS Agreement was amended in October 2022 to include additional territories for our BA3011 and BA3021 combination study trials. There was no impact to the Company's financial results for the three months ended March 31, 2023 or 2022 as a result of this agreement.

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2023
Related Party Transactions [Abstract]
Related party transactions	8. Related Party Transactions Himalaya Therapeutics SEZC Clinical Trial Services Agreement In April 2022, the Company entered into a Clinical Trial Agreement with Himalaya Therapeutics SEZC. Under the agreement, Himalaya Therapeutics SEZC agreed to provide services related to the initiation of clinical trials for BA3011 in the People’s Republic of China. For the first year following effectiveness of the agreement, the Company has agreed to pay Himalaya Therapeutics SEZC for the full-time use of two of its personnel. Payments are due and payable by BioAtla to Himalaya Therapeutics SEZC on a quarterly calendar basis and are non-refundable. For the three months ended March 31, 2023, the Company recognized $ 0.1 million in research and development expense related to the Clinical Trial Agreement. The Company did not have any amounts due from or due to Himalaya Therapeutics SEZC as of March 31, 2023.

401(k) Plan

401(k) Plan	3 Months Ended
	Mar. 31, 2023
Retirement Benefits [Abstract]
401(k) Plan	9. 401(k) Plan The Company maintains a defined contribution 401(k) plan available to eligible employees. Employee contributions are voluntary and are determined on an individual basis, limited to the maximum amount allowable under federal tax regulations. The Company, at its discretion, may make certain matching contributions to the 401(k) plan. To date, the Company has no t made any matching contributions.

Organization and Summary of S_2

Organization and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2023
Accounting Policies [Abstract]
Organization	Organization BioAtla, LLC was formed in Delaware in March 2007 and was converted to a Delaware corporation in July 2020 and renamed BioAtla, Inc. (the “Company”). The Company has a proprietary platform for creating biologics, including its conditionally active biologics (“CAB” or “CABs”). CABs have been designed to be active only under certain conditions found in diseased tissue, while remaining inactive in normal tissue. The Company is currently in clinical development of its two lead CAB antibody drug conjugates targeting AXL and ROR2 receptors, its CAB immune-oncology antibody targeting CTLA-4 and its CAB BiSpecific targeting EpCAM.
Basis of Presentation	Basis of Presentation The unaudited condensed financial statements as of March 31, 2023, and for the three months ended March 31, 2023 and 2022, have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (“SEC”), and with accounting principles generally accepted in the United States (“GAAP”) applicable to interim financial statements. These unaudited condensed financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, consisting of only normal recurring accruals, which in the opinion of management are necessary to present fairly the Company’s financial position as of the interim date and results of operations for the interim periods presented. Interim results are not necessarily indicative of results for a full year or future periods. These unaudited condensed financial statements should be read in conjunction with the Company’s audited financial statements for the year ended December 31, 2022 , included in its Annual Report on Form 10-K filed with the SEC on March 23, 2023.
Liquidity and Going Concern	Liquidity and Going Concern The Company has incurred cumulative operating losses and negative cash flows from operations since its inception and expects to continue to incur significant expenses and operating losses for the foreseeable future as it continues the development of its product candidates. As of March 31, 2023, the Company had an accumulated deficit of $ 320.3 million . The Company plans to continue to fund its losses from operations and capital funding needs through public or private equity or debt financings, or other sources. If the Company is not able to secure adequate additional funding, the Company may be forced to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, or suspend or curtail planned programs. Any of these actions could materially harm the Company’s business, results of operations and future prospects. Management is required to perform a two-step analysis of the Company’s ability to continue as a going concern. Management must first evaluate whether there are conditions and events that raise substantial doubt about the Company’s ability to continue as a going concern (Step 1). If management concludes that substantial doubt is raised, management is also required to consider whether its plans alleviate that doubt (Step 2). Management’s assessment included the preparation of cash flow forecasts resulting in management’s conclusion that there is not substantial doubt about the Company’s ability to continue as a going concern as its current cash and cash equivalents will be sufficient to fund the Company’s operations for a period of at least one year from the issuance date of these unaudited condensed financial statements.
Use of Estimates	Use of Estimates The preparation of the Company’s condensed financial statements requires it to make estimates and assumptions that impact the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in the Company’s condensed financial statements and accompanying notes. The most significant estimates in the Company’s condensed financial statements relate to accruals for research and development costs, and equity-based compensation. These estimates and assumptions are based on current facts, historical experience and various other factors believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities and the recording of revenue and expenses that are not readily apparent from other sources. Actual results may differ materially and adversely from these estimates. To the extent there are material differences between the estimates and actual results, the Company’s future results of operations will be affected.
Concentrations of Risk	Concentrations of Risk Financial instruments that potentially subject the Company to a significant concentration of credit risk consist primarily of cash and cash equivalents. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation expense represents the grant date fair value of equity awards, consisting of stock options, restricted stock units (“RSUs”) and employee stock purchase plan rights, over the requisite service period of the awards (usually the vesting period) on a straight-line basis. The Company estimates the fair value of stock option grants and employee stock purchase plan rights using the Black-Scholes option pricing model. Prior to the Company’s IPO, the fair value of RSUs was based on the estimated fair value of the underlying common stock on the date of grant and, subsequent to the Company’s IPO, the fair value is based on the closing sales price of the Company’s common stock on the date of grant. Equity award forfeitures are recognized as they occur.
Leases	Leases The Company determines if an arrangement is a lease at inception. An arrangement is or contains a lease if it conveys the right to control the use of an identified asset for a period of time in exchange for consideration. If a lease is identified, classification is determined at lease commencement. Operating lease liabilities are recognized at the present value of the future lease payments at the lease commencement date. The Company’s leases do not provide an implicit interest rate and therefore the Company estimates its incremental borrowing rate to discount lease payments. The incremental borrowing rate reflects the interest rate that the Company would have to pay to borrow on a collateralized basis an amount equal to the lease payments in a similar economic environment over a similar term. Operating lease right-of-use (“ROU”) assets are based on the corresponding lease liability adjusted for any lease payments made at or before commencement, initial direct costs, and lease incentives. Renewals or early terminations are not accounted for unless the Company is reasonably certain to exercise these options. Operating lease expense is recognized and the ROU asset is amortized on a straight-line basis over the lease term. Variable lease costs are not included in the calculation of the ROU asset and the related lease liability and are recognized as incurred. The Company has a single lease agreement with lease and non-lease components, which are accounted for as a single lease component. Payments for short-term leases, defined as leases with a term of twelve months or less, are expensed on a straight-line basis over the lease term. The Company does not currently have any short-term leases. Operating leases are included in operating lease right-of-use assets, operating lease liabilities, and operating lease liabilities, non-current on the Company’s balance sheets. The Company does not have any finance leases.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is defined as a change in equity during a period from transactions and other events and circumstances from non-owner sources. There have been no items qualifying as other comprehensive loss and, therefore, for all periods presented, the Company’s comprehensive loss was the same as its reported net loss.
Net Loss Per Share	Net Loss Per Share Basic net loss per common share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares and dilutive common stock equivalents outstanding for the period determined using the treasury-stock method. Dilutive common stock equivalents are comprised of RSUs, common stock options outstanding under the Company’s stock option plan, and contingently issuable shares under the Company's ESPP plan. Potentially dilutive securities not included in the calculation of diluted net loss per common share because to do so would be anti-dilutive are as follows (in common stock equivalents): Three Months Ended 2023 2022 Common stock options 6,214,418 2,447,902 Restricted stock units 400,293 862,573 ESPP shares 122,565 31,346 Total 6,737,276 3,341,821
Recent Accounting Pronouncements	Recent Accounting Pronouncements There were no new accounting standards that had a material impact on the Company’s financial statements during the three or three months ended March 31, 2023, and there were no other new accounting standards or pronouncements that were issued but not yet effective as of March 31, 2023 that the Company expects to have a material impact on its financial statements.

Organization and Summary of S_3

Organization and Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2023
Accounting Policies [Abstract]
Schedule of Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share	Potentially dilutive securities not included in the calculation of diluted net loss per common share because to do so would be anti-dilutive are as follows (in common stock equivalents): Three Months Ended 2023 2022 Common stock options 6,214,418 2,447,902 Restricted stock units 400,293 862,573 ESPP shares 122,565 31,346 Total 6,737,276 3,341,821

Balance Sheet Details (Tables)

Balance Sheet Details (Tables)	3 Months Ended
	Mar. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Schedule Of Prepaid Expenses Other Current Assets	Prepaid expenses and other current assets consist of the following (in thousands): March 31, December 31, Prepaid research and development $ 4,983 $ 4,385 Prepaid insurance 1,578 — Other prepaid expenses and current assets 469 539 Total $ 7,030 $ 4,924
Schedule of Property and Equipment	Property and equipment consist of the following (in thousands): Useful life March 31, December 31, Furniture, fixtures and office equipment 3 - 7 $ 2,141 $ 2,140 Laboratory equipment 5 2,315 2,265 Leasehold improvements 2 - 3 3,687 3,687 8,143 8,092 Less accumulated depreciation and amortization ( 5,658 ) ( 5,364 ) Total $ 2,485 $ 2,728
Schedule of Accounts Payable and Accrued Expenses	Accounts payable and accrued expenses consist of the following (in thousands): March 31, December 31, Accounts payable $ 8,054 $ 4,231 Accrued compensation 1,290 3,451 Accrued research and development 14,660 12,649 Other accrued expenses 707 1,279 Total $ 24,711 $ 21,610

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2023
Lessee Disclosure [Abstract]
Components of Lease Expense	The components of lease expense included in the Company’s statements of operations and loss include (in thousands): Three Months Ended March 31, 2023 2022 Operating lease expense $ 261 $ 261 Variable lease expense 147 132 Total lease expense, net $ 408 $ 393
Summary of Weighted Average Remaining Lease Term and Weighted Average Discount Rate	The weighted average remaining lease term and weighted average discount rate for operating leases were as follows: As of March 31, 2023 2022 Weighted average remaining lease term (in years) 2.25 3.25 Weighted average discount rate percentage 3.50 % 3.50 %
Supplemental Cash Flow Information Related to Leases	Supplemental cash flow information related to leases under which the Company is the lessee was as follows (amounts in thousands): Three Months Ended March 31, 2023 2022 Cash paid for amounts included in the measurement of operating leases $ 407 $ 377
Maturities of Operating Lease Liabilities	As of March 31, 2023, future minimum payments under the Company's non-cancelable operating lease under ASC 842 were as follows (in thousands): Operating Nine months ending December 31, 2023 $ 1,229 2024 1,685 2025 845 Thereafter — Total future lease payments 3,759 Less: imputed interest ( 151 ) Total operating lease liabilities $ 3,608

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2023
Equity [Abstract]
Schedule of Stock-Based Compensation Expense	Stock-based compensation expense for the three months ended March 31, 2023 and 2022 has been reported in the condensed statements of operations and comprehensive loss as follows (in thousands): Three Months Ended 2023 2022 Research and development $ 1,451 $ 1,300 General and administrative 2,163 2,332 Total $ 3,614 $ 3,632
Summary of Restricted Stock Units	The following table summarizes RSU activity under the 2020 Plan for the three months ended March 31, 2023: Number of Weighted - Average Outstanding at December 31, 2022 510,039 $ 18.00 Granted — $ — Vested ( 109,746 ) $ 18.00 Forfeited — $ — Outstanding at March 31, 2023 400,293 $ 18.00
Summary of Stock Option Activity	The following table summarizes stock option activity under the 2020 Plan for the three months ended March 31, 2023: Number of Weighted - Average Weighted -Average Aggregate Balance at December 31, 2022 2,736,918 $ 13.82 8.82 $ 3,636,148 Granted 3,485,500 $ 3.84 Exercised — $ — Forfeited ( 8,000 ) $ 3.72 Expired — $ — Balance at March 31, 2023 6,214,418 $ 8.24 9.30 $ 37,544 Vested and expected to vest at March 31, 2023 6,214,418 $ 8.24 9.30 $ 37,544 Exercisable at March 31, 2023 929,919 $ 18.25 8.28 $ —
Summary of Assumptions Used in Black-Scholes Model	The assumptions used in the Black-Scholes option pricing model to determine the fair value of stock option grants were as follows: Three Months Ended 2023 2022 Expected volatility 77.3 % 76.4 % Risk-free interest rate 3.85 % 0.52 % Expected dividend yield 0.0 % 0.0 % Expected term 6.10 years 6.08 years
Schedule of Common Stock Reserved for Future Issuance	Common stock reserved for future issuance are as follows in common equivalent shares: March 31, December 31, Common stock options and restricted stock units issued and outstanding 6,614,711 3,246,957 Awards available for future issuance under the 2020 Plan 1,073,515 3,012,554 Awards available for future issuance under the ESPP 1,578,352 1,070,402 Total common stock reserved for future issuance 9,266,578 7,329,913

Organization and Summary of S_4

Organization and Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Entity incorporation state country code	DE
Company formation date	2007-03
Accumulated deficit	$ (320,261)	$ (292,801)

Organization and Summary of S_5

Organization and Summary of Significant Accounting Policies - Schedule of Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	6,737,276	3,341,821
Common Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	6,214,418	2,447,902
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	400,293	862,573
ESPP Shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share	122,565	31,346

Balance Sheet Details - Schedul

Balance Sheet Details - Schedule Of Prepaid Expenses Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Balance Sheet Related Disclosures [Abstract]
Prepaid research and development	$ 4,983	$ 4,385
Prepaid insurance	1,578	0
Other prepaid expenses and current assets	469	539
Total	$ 7,030	$ 4,924

Balance Sheet Details - Sched_2

Balance Sheet Details - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 8,143	$ 8,092
Less accumulated depreciation and amortization	(5,658)	(5,364)
Total	2,485	2,728
Furniture Fixtures And Office Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 2,141	2,140
Furniture Fixtures And Office Equipment | Minimum
Property Plant And Equipment [Line Items]
Property plant and equipment useful life	3 years
Furniture Fixtures And Office Equipment | Maximum
Property Plant And Equipment [Line Items]
Property plant and equipment useful life	7 years
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property plant and equipment useful life	5 years
Property, plant and equipment, gross	$ 2,315	2,265
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 3,687	$ 3,687
Leasehold Improvements | Minimum
Property Plant And Equipment [Line Items]
Property plant and equipment useful life	2 years
Leasehold Improvements | Maximum
Property Plant And Equipment [Line Items]
Property plant and equipment useful life	3 years

Balance Sheet Details - Sched_3

Balance Sheet Details - Schedule of Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Balance Sheet Related Disclosures [Abstract]
Accounts payable	$ 8,054	$ 4,231
Accrued compensation	1,290	3,451
Accrued research and development	14,660	12,649
Other accrued expenses	707	1,279
Total	$ 24,711	$ 21,610

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	Mar. 31, 2023	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Assets measured at fair value	$ 0	$ 0
Liability measured at fair value	$ 0	$ 0

Leases (Additional Information)

Leases (Additional Information) (Details)	3 Months Ended
	Mar. 31, 2023
Leases [Abstract]
Lessor Operating Leases Option To Extend	5 years
Lessor, Operating Lease, Option to Extend	The lease expires in July 2025 and the Company has an option to extend the term of the lease for an additional five years. Additionally, the lease includes certain rent abatement, rent escalations, tenant improvement allowances and additional charges for common area maintenance and other costs.

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Leases [Abstract]
Operating lease expense	$ 261	$ 261
Variable lease expense	147	132
Lease, Cost, Total	$ 408	$ 393

Leases - Summary of Weighted Av

Leases - Summary of Weighted Average Remaining Lease Term And Weighted Average Discount Rate (Details)	Mar. 31, 2023	Mar. 31, 2022
Leases [Abstract]
Weighted average remaining lease term (in years)	2 years 3 months	3 years 3 months
Weighted average discount rate percentage	3.50%	3.50%

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Information Related to Leases (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Leases [Abstract]
Cash paid for amounts included in the measurement of operating leases	$ 407	$ 377

Leases - Maturities of Operatin

Leases - Maturities of Operating Lease Liabilities (Details) $ in Thousands	Mar. 31, 2023 USD ($)
Leases [Abstract]
Nine months ending December 31, 2023	$ 1,229
2024	1,685
2025	845
Thereafter	0
Total future lease payments	3,759
Less: imputed interest	(151)
Total operating lease liabilities	$ 3,608

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)			3 Months Ended
	Feb. 26, 2023	Jan. 01, 2021	Mar. 31, 2023	Dec. 31, 2022
Class Of Stock [Line Items]
Total fair value of options vested			$ 2,700,000
Total number of common shares reserved for issuance			9,266,578	7,329,913
Common Stock, Shares Authorized			350,000,000	350,000,000
Equity Option
Class Of Stock [Line Items]
Share-based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount			$ 22,400,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition			3 years 6 months
Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value			$ 2.69
Restricted Stock Units (RSUs)
Class Of Stock [Line Items]
Share-based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount			$ 7,200,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition			1 year 1 month 6 days
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period			109,746
2020 Equity Incentive Plan [Member]
Class Of Stock [Line Items]
Common shares authorized for issuance			9,196,970	7,658,509
Shares available for awards, description		4
Vesting percentage			25%
Vesting period			36 months
Vesting terms, description			ten years
Modification of Two Thousand Twenty Equity Incentive Plan and certain awards [Member] | Equity Option
Class Of Stock [Line Items]
Share-Based Goods and Nonemployee Services Transaction, Modification of Terms, Incremental Compensation Cost	$ 123,000
Modification of Two Thousand Twenty Equity Incentive Plan and certain awards [Member] | Equity Option | Board Of Directors
Class Of Stock [Line Items]
Number of options unvested on modification date, number of shares	574,244
Recalculated compensation cost of the modified options	$ 962,000
RSUs fully vested on the modification date, number of shares	130,699
Modification of Two Thousand Twenty Equity Incentive Plan and certain awards [Member] | Restricted Stock Units (RSUs) | Board Of Directors
Class Of Stock [Line Items]
Recalculated compensation cost on the modified RSUs	$ 416,000
RSUs unvested on modification date, number of shares	139,730
Employees Stock Purchase Plan [Member]
Class Of Stock [Line Items]
Total number of common shares reserved for issuance			1,578,352
Common Stock, Shares Authorized			1,737,098	1,229,148
Share-Based Compensation Arrangement by Share-Based Payment Award, Purchase Price of Common Stock, Percent			15%
Share Based Compensation Arrangement By Share Based Payment Award Percentage Of Outstanding Stock Maximum			1%
Increase in issuance of common stock			929,658
Class B Common Stock
Class Of Stock [Line Items]
Common Stock, Shares Authorized			15,368,569	15,368,569

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Class Of Stock [Line Items]
Stock-based compensation	$ 3,614	$ 3,632
Research and Development Expense
Class Of Stock [Line Items]
Stock-based compensation	1,451	1,300
General and Administrative Expense
Class Of Stock [Line Items]
Stock-based compensation	$ 2,163	$ 2,332

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Restricted Stock Units (Details) - Restricted Stock Units (RSUs)	3 Months Ended
	Mar. 31, 2023 $ / shares shares
Class Of Stock [Line Items]
Number of Outstanding Shares, Beginning Balance | shares	510,039
Number of Shares, Granted | shares	0
Number of Shares, Vested | shares	(109,746)
Number of Shares, Forfeited | shares	0
Number of Outstanding Shares, Ending Balance | shares	400,293
Weighted Average Grant Date Fair Value, Beginning Balance | $ / shares	$ 18
Weighted Average Grant Date Fair Value, Granted | $ / shares	0
Weighted Average Grant Date Fair Value, Vested | $ / shares	18
Weighted Average Grant Date Fair Value, Forfeited | $ / shares	0
Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 18

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Stock Option Activity (Details) - Equity Option - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Beginning Balance	2,736,918
Granted, Number of Shares	3,485,500
Forfeited, Number of Shares	(8,000)
Exercised, Number of Shares	0
Expired, Number of Shares	0
Number of Shares, Ending Balance	6,214,418	2,736,918
Vested and expected to vest, Number of Shares	6,214,418
Exercisable, Number of Shares	929,919
Outstanding, Beginning Balance, Weighted-Average Exercise Price per Share	$ 13.82
Granted, Weighted-Average Exercise Price per Share	3.84
Forfeited, Weighted-Average Exercise Price per Share	3.72
Exercised, Weighted-Average Exercise Price per Share	0
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Expirations in Period, Weighted Average Exercise Price	0
Outstanding, Ending Balance, Weighted-Average Exercise Price per Share | $ / shares	8.24	$ 13.82
Vested and expected to vest, Weighted-Average Exercise Price per Share	8.24
Exercisable Weighted-Average Exercise Price per Share	$ 18.25
Outstanding, Weighted-Average Remaining Contractual Term (years)	9 years 3 months 18 days	8 years 9 months 25 days
Vested and expected to vest, Weighted-Average Remaining Contractual Term (years)	9 years 3 months 18 days
Exercisable, Weighted-Average Remaining Contractual Term (years)	8 years 3 months 10 days
Outstanding, Aggregate Intrinsic Value	$ 37,544	$ 3,636,148
Vested and expected to vest, Aggregate Intrinsic Value	37,544
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Intrinsic Value	$ 0

Stockholders' Equity - Summar_3

Stockholders' Equity - Summary of Assumptions Used in Black-Scholes Model (Details)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Stockholders' Equity Note [Abstract]
Expected volatility	77.30%	76.40%
Risk-free interest rate	3.85%	0.52%
Expected dividend yield	0%	0%
Expected term	6 years 1 month 6 days	6 years 29 days

Stockholders' Equity - Schedu_2

Stockholders' Equity - Schedule of Common Stock Reserved for Future Issuance (Details) - shares	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Class Of Stock [Line Items]
Common Stock, Shares, Issued	47,637,321	46,336,166
Common Stock, Shares, Outstanding	47,637,321	46,336,166
Total number of common shares reserved for issuance	9,266,578	7,329,913
Common Stock Options and Restricted Stock Units [Member]
Class Of Stock [Line Items]
Common Stock, Shares, Issued	6,614,711	3,246,957
Common Stock, Shares, Outstanding	6,614,711	3,246,957
2020 Plan [Member]
Class Of Stock [Line Items]
Awards available for future issuance	1,073,515	3,012,554
Employees Stock Purchase Plan [Member]
Class Of Stock [Line Items]
Awards available for future issuance	1,578,352	1,070,402
Total number of common shares reserved for issuance	1,578,352

Collaboration, License and Op_2

Collaboration, License and Option Agreements - Additional Information (Details) - USD ($)		3 Months Ended		12 Months Ended
	Nov. 18, 2021	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2019	Dec. 31, 2022
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration Amendment Date				2019-03
Revenues		$ 0	$ 0
Liability to licensor		$ 19,806,000			$ 19,806,000
BeiGene
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration Amendment Date		2021-11
Upfront Non-Refundable Payment				$ 25,000,000
Revenues		$ 0	$ 0
Current portion of deferred revenue	$ 19,800,000
License termination information, Description	In the event the license is terminated, the liability will be extinguished with no further payment to BeiGene.
Liability to licensor		$ 19,800,000			$ 19,800,000

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Related Party Transaction [Line Items]
Research and development expense	$ 21,697	$ 16,923
Himalaya Therapeutics SEZC
Related Party Transaction [Line Items]
Description of agreement with related party	In April 2022, the Company entered into a Clinical Trial Agreement with Himalaya Therapeutics SEZC. Under the agreement, Himalaya Therapeutics SEZC agreed to provide services related to the initiation of clinical trials for BA3011 in the People’s Republic of China. For the first year following effectiveness of the agreement, the Company has agreed to pay Himalaya Therapeutics SEZC for the full-time use of two of its personnel. Payments are due and payable by BioAtla to Himalaya Therapeutics SEZC on a quarterly calendar basis and are non-refundable. For the three months ended March 31, 2023, the Company recognized $0.1 million in research and development expense related to the Clinical Trial Agreement. The Company did not have any amounts due from or due to Himalaya Therapeutics SEZC as of March 31, 2023.
Research and development expense	$ 100

401(k) Plan - Additional Inform

401(k) Plan - Additional Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($)
Retirement Benefits [Abstract]
Contributions made by Company	$ 0