ALX Oncology (ALXO) S-1 7 Dec 20 IPO registration Financial data

Cover

Cover	9 Months Ended
	Sep. 30, 2020
Cover [Abstract]
Document Type	S-1
Amendment Flag	false
Entity Registrant Name	ALX ONCOLOGY HOLDINGS INC
Entity Central Index Key	0001810182
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Apr. 01, 2020	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash	$ 259,484		$ 9,017
Receivables due from related-party	527		536
Prepaid expenses and other current assets	2,393		256
Total current assets	262,404		9,809
Property and equipment, net	45		860
Other assets			7
Total assets	262,449		10,676
Current liabilities:
Accounts payable	1,421		3,748
Accrued expenses and other current liabilities	3,205		1,236
Term loan-current	2,571
Total current liabilities	7,197		4,984
Term loan	3,189		5,421
Other long-term liabilities	47		547
Deferred rent
Total liabilities	10,433		10,952
Commitments and contingencies
Convertible preferred stock			70,363
Shareholders' equity (deficit):
Preferred stock, value
Common stock, value	37		3
Additional paid-incapital	351,727		2,140
Accumulated deficit	(99,748)		(72,782)
Total shareholders' equity (deficit)	252,016		(70,639)	$ (51,778)
Total liabilities and stockholders' equity	$ 262,449		10,676
Series A Convertible Preferred Stock
Current liabilities:
Convertible preferred stock			60,933
Series B Convertible Preferred Stock
Current liabilities:
Convertible preferred stock			9,430
Predecessor Company
Current assets:
Cash			9,017	8,262
Receivables due from related-party			536	932
Prepaid expenses and other current assets			256	1,014
Total current assets			9,809	10,208
Property and equipment, net			860	956
Other assets			7
Total assets			10,676	11,164
Current liabilities:
Accounts payable			3,748	697
Accrued expenses and other current liabilities			1,236	1,176
Total current liabilities			4,984	1,873
Term loan			5,421
Other long-term liabilities			412
Deferred rent			135	136
Total liabilities			10,952	2,009
Commitments and contingencies
Convertible preferred stock			70,363	60,933
Shareholders' equity (deficit):
Common stock, value			3	3
Additional paid-incapital			2,140	1,758
Accumulated deficit			(72,782)	(53,539)
Total shareholders' equity (deficit)			(70,639)	(51,778)
Total liabilities and stockholders' equity			10,676	11,164
Predecessor Company | Series A Convertible Preferred Stock
Current liabilities:
Convertible preferred stock			60,933	$ 60,933
Predecessor Company | Series B Convertible Preferred Stock
Current liabilities:
Convertible preferred stock			$ 9,430

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Convertible preferred stock, shares authorized		11,567,003
Convertible preferred stock, liquidation preference		$ 83,585
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	1,000,000,000	1,519,618,271
Common stock, shares issued	37,107,522	3,166,946
Common stock, shares outstanding	37,107,522	3,166,946
Predecessor Company
Convertible preferred stock, shares authorized		11,567,003	9,421,633
Convertible preferred stock, liquidation preference		$ 83,585	$ 69,863
Common stock, par value		$ 0.001	$ 0.001
Common stock, shares authorized		1,519,618,271	1,519,618,271
Common stock, shares issued		3,166,946	3,161,747
Common stock, shares outstanding		3,166,946	3,161,747
Series A Convertible Preferred Stock
Convertible preferred stock, par value	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	0	9,421,633
Convertible preferred stock, shares issued	0	9,297,081
Convertible preferred stock, shares outstanding	0	9,297,081
Convertible preferred stock, liquidation preference		$ 73,571
Series A Convertible Preferred Stock | Predecessor Company
Convertible preferred stock, par value		$ 0.001	$ 0.001
Convertible preferred stock, shares authorized		9,421,633	9,421,633
Convertible preferred stock, shares issued		9,297,081	9,297,081
Convertible preferred stock, shares outstanding		9,297,081	9,297,081
Convertible preferred stock, liquidation preference		$ 73,571	$ 69,863
Series B Convertible Preferred Stock
Convertible preferred stock, par value	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	0	2,145,370
Convertible preferred stock, shares issued	0	1,016,727
Convertible preferred stock, shares outstanding	0	1,016,727
Convertible preferred stock, liquidation preference		$ 10,014
Series B Convertible Preferred Stock | Predecessor Company
Convertible preferred stock, par value		$ 0.001	$ 0.001
Convertible preferred stock, shares authorized		2,145,370	2,145,370
Convertible preferred stock, shares issued		1,016,727	0
Convertible preferred stock, shares outstanding		1,016,727	0
Convertible preferred stock, liquidation preference		$ 10,014	$ 0

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Operating expenses:
Research and development	$ 5,328	$ 2,210	$ 16,819	$ 9,571
General and administrative	4,481	938	9,126	2,205
Cost of services for related-party revenue		1,142	1,075	3,257
Total operating expenses	9,809	4,290	27,020	15,033
Loss from operations	(9,809)	(3,034)	(25,838)	(11,450)
Interest expense	(226)		(660)
Other expense, net	(111)	(2)	(409)	(4)
Loss before income taxes	(10,146)	(3,036)	(26,907)	(11,454)
Income tax provision	(35)	(8)	(59)	(25)
Net loss and comprehensive loss	(10,181)	(3,044)	(26,966)	(11,479)
Cumulative dividends allocated to preferred shareholders	(578)	(1,071)	(5,202)	(2,957)
Net loss attributable to common stockholders	$ (10,759)	$ (4,115)	$ (32,168)	$ (14,436)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.36)	$ (1.33)	$ (2.67)	$ (4.72)
Weighted-average ordinary shares used to compute net loss per share attributable to ordinary shareholders, basic and diluted	29,664,122	3,100,544	12,052,876	3,061,082
Predecessor Company
Operating expenses:
Research and development					$ 16,306	$ 11,270
General and administrative					3,313	2,601
Cost of services for related-party revenue					4,360	1,880
Total operating expenses					23,979	15,751
Loss from operations					(19,183)	(13,684)
Interest expense					(21)
Other expense, net					(5)	(2)
Loss before income taxes					(19,209)	(13,686)
Income tax provision					(34)	(45)
Net loss and comprehensive loss					(19,243)	(13,731)
Cumulative dividends allocated to preferred shareholders					(4,028)	(3,671)
Net loss attributable to common stockholders					$ (23,271)	$ (17,402)
Net loss per share attributable to common stockholders, basic and diluted					$ (7.56)	$ (6.33)
Weighted-average ordinary shares used to compute net loss per share attributable to ordinary shareholders, basic and diluted					3,076,461	2,750,838
Pro forma net loss attributable to ordinary shareholders per share, basic and diluted (unaudited)					$ (1.34)
Weighted-average ordinary shares used to compute pro forma net loss per share attributable to ordinary shareholders, basic and diluted (unaudited)					14,330,300
Related Party
Related-party revenue		$ 1,256	$ 1,182	$ 3,583
Related Party | Predecessor Company
Related-party revenue					$ 4,796	$ 2,067

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Predecessor Company	Predecessor CompanyConvertible Preferred Stock	Predecessor CompanyCommon Stock	Predecessor CompanyAdditional Paid-in Capital	Predecessor CompanyAccumulated Deficit
Temporary equity, balance at Dec. 31, 2017							$ 60,933
Temporary equity, shares at Dec. 31, 2017							9,297,081
Net loss						$ (13,731)				$ (13,731)
Share-based compensation						269			$ 269
Vesting of early exercised share options						92			92
Repurchase of unvested early exercised share options								(6,899)
Temporary equity, balance at Dec. 31, 2018		9,297,081					9,297,081
Temporary equity, balance at Dec. 31, 2018		$ 60,933				60,933	$ 60,933
Balance at Dec. 31, 2017						$ (38,415)		$ 3	1,390	(39,808)
Balance, shares at Dec. 31, 2017								3,205,421
Repurchase of ordinary shares								(43,689)
Exercise of share options, shares						6,914		6,914
Exercise of share options						$ 7			7
Balance at Dec. 31, 2018	$ (51,778)		$ 3	$ 1,758	$ (53,539)	(51,778)		$ 3	1,758	(53,539)
Balance, shares at Dec. 31, 2018			3,161,747					3,161,747
Net loss	(4,238)				(4,238)
Share-based compensation	76			76
Vesting of early exercised share options	21			21
Temporary equity, balance at Mar. 31, 2019		9,297,081
Temporary equity, balance at Mar. 31, 2019		$ 60,933
Balance at Mar. 31, 2019	(55,919)		$ 3	1,855	(57,777)
Balance, shares at Mar. 31, 2019			3,161,747
Temporary equity, balance at Dec. 31, 2018		$ 60,933				60,933	$ 60,933
Temporary equity, shares at Dec. 31, 2018		9,297,081					9,297,081
Net loss	(11,479)
Temporary equity, balance at Sep. 30, 2019		10,313,808
Temporary equity, balance at Sep. 30, 2019		$ 70,363
Balance at Dec. 31, 2018	(51,778)		$ 3	1,758	(53,539)	(51,778)		$ 3	1,758	(53,539)
Balance, shares at Dec. 31, 2018			3,161,747					3,161,747
Balance at Sep. 30, 2019	(62,976)		$ 3	2,039	(65,018)
Balance, shares at Sep. 30, 2019			3,161,747
Temporary equity, balance at Dec. 31, 2018		$ 60,933				60,933	$ 60,933
Temporary equity, shares at Dec. 31, 2018		9,297,081					9,297,081
Issuance of convertible preferred stock, net of issuance costs							$ 9,430
Issuance of convertible preferred stock, net of issuance costs, shares							1,016,727
Net loss						(19,243)				(19,243)
Share-based compensation						297			297
Vesting of early exercised share options						75			75
Temporary equity, balance at Dec. 31, 2019		10,313,808					10,313,808
Issuance of convertible preferred stock, net of issuance costs, shares							1,016,727
Issuance of convertible preferred stock, net of issuance costs							$ 9,430
Temporary equity, balance at Dec. 31, 2019	70,363	$ 70,363				70,363	70,363
Balance at Dec. 31, 2018	(51,778)		$ 3	1,758	(53,539)	$ (51,778)		$ 3	1,758	(53,539)
Balance, shares at Dec. 31, 2018			3,161,747					3,161,747
Exercise of share options, shares						5,199		5,199
Exercise of share options						$ 10			10
Balance at Dec. 31, 2019	(70,639)		$ 3	2,140	(72,782)	(70,639)		$ 3	2,140	(72,782)
Balance, shares at Dec. 31, 2019			3,166,946					3,166,946
Temporary equity, balance at Mar. 31, 2019		$ 60,933
Temporary equity, shares at Mar. 31, 2019		9,297,081
Issuance of convertible preferred stock, net of issuance costs		$ 9,430
Issuance of convertible preferred stock, net of issuance costs, shares		1,016,727
Net loss	(4,197)				(4,197)
Share-based compensation	60			60
Vesting of early exercised share options	20			20
Temporary equity, balance at Jun. 30, 2019		10,313,808
Issuance of convertible preferred stock, net of issuance costs, shares		1,016,727
Issuance of convertible preferred stock, net of issuance costs		$ 9,430
Temporary equity, balance at Jun. 30, 2019		$ 70,363
Balance at Mar. 31, 2019	(55,919)		$ 3	1,855	(57,777)
Balance, shares at Mar. 31, 2019			3,161,747
Balance at Jun. 30, 2019	(60,036)		$ 3	1,935	(61,974)
Balance, shares at Jun. 30, 2019			3,161,747
Net loss	(3,044)				(3,044)
Share-based compensation	86			86
Vesting of early exercised share options	18			18
Temporary equity, balance at Sep. 30, 2019		10,313,808
Temporary equity, balance at Sep. 30, 2019		$ 70,363
Balance at Sep. 30, 2019	(62,976)		$ 3	2,039	(65,018)
Balance, shares at Sep. 30, 2019			3,161,747
Temporary equity, balance at Dec. 31, 2019	70,363	$ 70,363				70,363	$ 70,363
Temporary equity, shares at Dec. 31, 2019		10,313,808					10,313,808
Issuance of convertible preferred stock, net of issuance costs		$ 104,680
Issuance of convertible preferred stock, net of issuance costs, shares		11,055,966
Net loss	(5,454)				(5,454)
Share-based compensation	151			151
Vesting of early exercised share options	16			16
Temporary equity, balance at Mar. 31, 2020		21,369,774
Issuance of convertible preferred stock, net of issuance costs, shares		11,055,966
Issuance of convertible preferred stock, net of issuance costs		$ 104,680
Temporary equity, balance at Mar. 31, 2020		175,043
Balance at Dec. 31, 2019	(70,639)		$ 3	2,140	(72,782)	(70,639)		$ 3	2,140	(72,782)
Balance, shares at Dec. 31, 2019			3,166,946					3,166,946
Balance at Mar. 31, 2020	(75,926)		$ 3	2,307	(78,236)
Balance, shares at Mar. 31, 2020			3,166,946
Temporary equity, balance at Dec. 31, 2019	70,363	$ 70,363				70,363	$ 70,363
Temporary equity, shares at Dec. 31, 2019		10,313,808					10,313,808
Net loss	(26,966)
Balance at Dec. 31, 2019	(70,639)		$ 3	2,140	(72,782)	$ (70,639)		$ 3	$ 2,140	$ (72,782)
Balance, shares at Dec. 31, 2019			3,166,946					3,166,946
Balance at Sep. 30, 2020	252,016		$ 37	351,727	(99,748)
Balance, shares at Sep. 30, 2020			37,107,522
Temporary equity, balance at Mar. 31, 2020		$ 175,043
Temporary equity, shares at Mar. 31, 2020		21,369,774
Net loss	(11,331)				(11,331)
Share-based compensation	2,853			2,853
Vesting of early exercised share options	6			6
Temporary equity, balance at Jun. 30, 2020		21,369,774
Temporary equity, balance at Jun. 30, 2020		$ 175,043
Balance at Mar. 31, 2020	(75,926)		$ 3	2,307	(78,236)
Balance, shares at Mar. 31, 2020			3,166,946
Balance at Jun. 30, 2020	(84,398)		$ 3	5,166	(89,567)
Balance, shares at Jun. 30, 2020			3,166,946
Net loss	(10,181)				(10,181)
Conversion of convertible preferred stock into common stock, shares		(21,369,774)	21,369,774
Share-based compensation	689			689
Conversion of convertible preferred stock into common stock	175,043	$ (175,043)	$ 21	175,022
Reclassification of warrants from liability to equity	1,019			1,019
Vesting of early exercised share options	4			4
Cumulative dividends			$ 3	(3)
Cumulative dividends, shares			2,564,759
Issuance of common stock in connection with initial public offering, net of underwriter discounts and issuance costs	169,541		$ 10	169,531
Issuance of common stock in connection with initial public offering, net of underwriter discounts and issuance costs, shares			9,775,000
Issuance of common stock under equity incentive plans	299			299
Issuance of common stock under equity incentive plans, shares			182,111
Issuance of common stock upon net exercise of warrants			48,932
Balance at Sep. 30, 2020	$ 252,016		$ 37	$ 351,727	$ (99,748)
Balance, shares at Sep. 30, 2020			37,107,522

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Operating activities
Net loss	$ (26,966)	$ (11,479)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	197	317
Share-based compensation expense	3,693	222
Amortization of term loan discount and issuance costs	339
Changes in fair value of compound derivative liability and warrants	650
Gain on assignment of lease	(126)
Changes in operating assets and liabilities
Receivables due from related-party	9	(414)
Prepaid expenses and other current assets	(2,137)	360
Accounts payable	(2,323)	(91)
Accrued expenses and other current liabilities	1,995	(291)
Deferred rent	(5)	1
Net cash used in operating activities	(24,674)	(11,375)
Investing activities
Purchase of property and equipment	(20)	(415)
Proceeds from assets held for sale	641
Net cash provided by (used in) investing activities	621	(415)
Financing activities
Proceeds from equity offerings, net	172,724
Payments of offering costs	3,183
Proceeds from exercise of common stock under equity incentive plans	299
Cash paid for repurchase of ordinary shares	68,452	6,829
Proceeds from issuance of convertible preferred stock, net	36,228	2,601
Net cash provided by financing activities	274,520	9,430
Net (decrease) increase in cash	250,467	(2,360)
Cash and cash equivalents at beginning of period	9,017	8,262	$ 8,262
Cash and cash equivalents at end of period	259,484	5,902	9,017	$ 8,262
Supplemental disclosure
Cash paid for interest	295
Cash paid for taxes	47
Supplemental disclosure of non-cash investing and financing activities
Vesting of early exercised share options	26	59
Acquisition of property and equipment in accounts payable	3
Conversion of convertible preferred stock into common stock upon closing of initial public offering	175,043
Accumulated dividend on convertible preferred stock	3
Predecessor Company
Operating activities
Net loss			(19,243)	(13,731)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization			429	431
Share-based compensation expense			297	269
Amortization of term loan discount and issuance costs			11
Changes in operating assets and liabilities
Receivables due from related-party			396	(932)
Prepaid expenses and other current assets			744	897
Other assets			7
Accounts payable			2,976	(269)
Accrued expenses and other current liabilities			134	9
Deferred rent				136
Net cash used in operating activities			(14,249)	(13,190)
Investing activities
Proceeds from assets held for sale			353	653
Net cash provided by (used in) investing activities			(353)	(653)
Financing activities
Proceeds from equity offerings, net			6,829
Payments of offering costs			2,601
Proceeds from exercise of common stock under equity incentive plans			10	7
Cash paid for repurchase of ordinary shares				(6)
Proceeds from issuance of convertible preferred stock, net			5,917
Net cash provided by financing activities			15,357	1
Net (decrease) increase in cash			755	(13,842)
Cash and cash equivalents at beginning of period	$ 9,017	$ 8,262	8,262	22,104
Cash and cash equivalents at end of period			9,017	8,262
Supplemental disclosure of non-cash investing and financing activities
Fair value of compound derivative liability and warrant liability related to term loan			412
Vesting of early exercised share options			75	92
Acquisition of property and equipment in accounts payable				$ 20
Debt issuance costs in accounts payable			$ 95

Organization

Organization	Apr. 01, 2020	Sep. 30, 2020
Accounting Policies [Abstract]
Organization	1. Organization ALX Oncology Holdings Inc., or the Company, was formed as a Delaware corporation on April 1, 2020, or Inception. The Company was formed for the purpose of completing the initial public offering and related transactions in order to carry on the business of ALX Oncology Limited. After Inception, ALX Oncology Limited became a wholly-owned subsidiary of the Corporation as result of the internal reorganization. As part of the transaction, all of the equity, option and warrant holders of ALX Oncology Limited became equity, option and warrant holders of the Company, holding the same number of corresponding shares, options and/or warrants in the Company as they did in ALX Oncology Limited immediately prior to the reorganization.	(1) ORGANIZATION Organization ALX Oncology Holdings Inc., or the Company, was formed as a Delaware corporation on April 1, 2020, or Inception. The Company was formed for the purpose of completing the Company’s initial public offering of its common stock and related transactions in order to carry on the business of ALX Oncology Limited. After Inception, ALX Oncology Limited became a wholly-owned subsidiary of the Company as a result of the internal reorganization. As part of the internal reorganization, all of the equity, option and warrant holders of ALX Oncology Limited became equity, option and warrant holders of the Company, holding the same number of corresponding shares, options and/or warrants in the Company as they did in ALX Oncology Limited immediately prior to the internal reorganization. The information included herein is presented as that of ALX Oncology Holdings Inc. unless such information refers to a date prior to April 1, 2020, in which case it will reflect that of ALX Oncology Limited, the predecessor company. The Company is a clinical-stage immuno-oncology company focused on helping patients fight cancer by developing therapies that block the CD47 checkpoint pathway and bridge the innate and adaptive immune system. The Company owns subsidiaries, consisting of ALX Oncology Limited, incorporated in Ireland; ALX Oncology Inc., incorporated in the United States, and Alexo International Holdings Ltd, incorporated in Malta; Alexo Therapeutics International, incorporated in the Cayman Islands, which is a wholly-owned subsidiary of Alexo International Holdings Ltd. and Sirpant Therapeutics, incorporated in the Cayman Islands, which is a wholly-owned subsidiary of Alexo Therapeutics International, or collectively, the Subsidiaries. As of September 30, 2020, the Company has devoted substantially all of its efforts to the formation and financing of the Company, as well as product development, and has not realized product revenues from its planned principal operations. The Company has no manufacturing facilities and all manufacturing related activities are contracted out to third-party service providers. In July 2020, the Company consummated its initial public offering and issued 9,775,000 shares of common stock for net proceeds of approximately $169.5 million, after deducting underwriting discounts and commissions of $13.0 million and offering-related expenses of $3.2 million. Upon the closing of the initial public offering, all shares of convertible preferred stock outstanding and accrued cumulative dividends were automatically converted into 23,934,533 shares of common stock. On July 21, 2020, the Company’s amended and restated certificate of incorporation became effective, authorizing 1,000,000,000 shares of common stock and 100,000,000 shares of undesignated preferred stock. Liquidity and Capital Resources As of September 30, 2020, the Company had cash and cash equivalents of $259.5 million, which will be sufficient to fund its planned operations for a period of at least twelve months following the issuance of these condensed consolidated financial statements. Management expects to incur additional losses in the future to conduct product candidate research and development and to conduct pre-commercialization out-license

Significant Accounting Policies

Significant Accounting Policies	Apr. 01, 2020	Sep. 30, 2020
Accounting Policies [Abstract]
Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Preparation The balance sheet is presented in accordance with accounting principles generally accepted in the United States of America, or U.S. GAAP. The statements of operations and comprehensive loss, stockholders’ equity, and cash flows have not been presented because there have been no activities at inception of this entity. Underwriting Commissions and Offering Costs Underwriting commissions and offering costs to be incurred in connection with the Company’s common stock offerings will be reflected as a reduction in additional paid-in Organizational Costs Organizational costs for costs incurred to organize the Company will be expensed as incurred.	(2) SIGNIFICANT ACCOUNTING POLICIES Basis of Preparation These condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or U.S. GAAP, and the applicable rules and regulations of the U.S. Securities and Exchange Commission, or SEC, for interim reporting. Principles of Consolidation All intercompany balances and transactions have been eliminated in consolidation. Unaudited Condensed Consolidated Financial Statements The condensed consolidated balance sheet as of September 30, 2020, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2019 and 2020, the condensed consolidated statements of convertible preferred stock and stockholders’ equity (deficit) for the three and nine months ended September 30, 2019 and 2020, and the condensed consolidated statements of cash flows for the nine months ended September 30, 2019 and 2020, are unaudited. These unaudited condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s financial position as of September 30, 2020, and its results of operations for the periods presented. The results of operations for the three and nine months ended September 30, 2020, are not necessarily indicative of the results to be expected for any subsequent periods, including the year ended December 31, 2020, and therefore should not be relied upon as an indicator of future results. The condensed consolidated balance sheet as of December 31, 2019 included herein was derived from the audited consolidated financial statements as of that date. The accompanying condensed consolidated financial statements and related notes should be read in conjunction with the audited consolidated financial statements for the year ended December 31, 2019 and the notes thereto, which are included in the Company’s final prospectus for the Company’s initial public offering filed pursuant to Rule 424(b)(4) under the Securities Act of 1933, as amended, with the SEC on July 17, 2020. Reverse Stock Split On July 8, 2020, the Company’s board of directors approved an amendment to the Company’s certificate of incorporation to effect a 1-for-6.5806 Use of Estimates The preparation of the condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. On an ongoing basis, management evaluates its estimates, including those related to the estimated useful lives of long-lived assets, clinical trial accruals, fair value of assets and liabilities, Series B convertible preferred stock warrant liability, term loan compound derivative liability, term loan, valuation of the Company’s common stock, income taxes and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates. Cash and Cash Equivalents The Company holds its cash and cash equivalents in checking and money market accounts. The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. Cash equivalents consist primarily of amounts invested in money market accounts and are stated at fair value. Concentration of Credit Risk and Other Risks and Uncertainties Financial instruments that potentially subject the Company to a 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, and invests in money market funds. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash and cash equivalents. The Company has not experienced any losses on its deposits of cash and cash equivalents. The Company’s future results of operations involve a number of other risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, uncertainty of results of clinical trials and reaching milestones, uncertainty of regulatory approval of the Company’s potential product candidates, uncertainty of market acceptance of the Company’s product candidates, competition from substitute products and larger companies, securing and protecting proprietary technology, strategic relationships and dependence on key individuals or sole-source suppliers. The Company’s product candidates require approvals from the U.S. Food and Drug Administration, or FDA, and comparable foreign regulatory agencies prior to commercial sales in their respective jurisdictions. There can be no assurance that any product candidates will receive the necessary approvals. If the Company was denied approval, approval was delayed or the Company was unable to maintain approval for any product candidate, it could have a materially adverse impact on the Company. Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation of property and equipment is provided using the straight-line method over the estimated useful lives of the assets. Upon sale or retirement of assets, the cost and related accumulated depreciation or amortization are removed from the condensed consolidated balance sheet and the resulting gain or loss is reflected in the condensed consolidated statement of operations and comprehensive loss. Maintenance and repairs are charged to the condensed consolidated statement of operations and comprehensive loss as incurred. Deferred Offering Costs The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process paid-in Impairment of Long-Lived Assets The Company reviews property and equipment for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amount to the future undiscounted net cash flows which the asset or asset group are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured as the amount by which the carrying amount of the assets exceeds its fair value. Fair value is determined using various valuation techniques including discounted cash flow models, quoted market values and third-party independent appraisals, as considered necessary. There were no impairment charges recognized in the three and nine months ended September 30, 2019 and 2020. Fair Value of Financial Instruments The Company applies fair value accounting for all financial assets and liabilities and nonfinancial assets and liabilities that are required to be recognized or disclosed at fair value in the condensed consolidated financial statements. The Company defines fair value as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Where observable prices or inputs are not available valuation models are applied. These valuation techniques involve some level of management estimation and judgment, the degree of which is dependent on the price transparency for the instruments or market and the instruments’ complexity. The Company’s financial instruments consist of cash and cash equivalents, receivables due from related-party, accounts payable, the term loan compound derivative liability and the Series B convertible preferred stock warrant liability. The term loan compound derivative liability and the Series B convertible preferred stock warrant liability are re-measured Term Loan The Company accounts for the Loan and Security Agreement, dated as of December 20, 2019, as amended, with Silicon Valley Bank, or SVB, and WestRiver Innovation Lending Fund VIII, LP, or WestRiver, collectively as lenders, and SVB, as administrative agent and collateral agent, as a liability measured at net proceeds less debt discount and is accreted to the face value of the term loan over its expected term using the effective interest method. The Company considers whether there are any embedded features in its debt instruments that require bifurcation and separate accounting as derivative financial instruments pursuant to Accounting Standards Codification, or ASC, Topic 815, Derivatives and Hedging Convertible Preferred Stock The Company records convertible preferred stock net of issuance costs on the dates of issuance, which represents the carrying value. In the event of a change of control of the Company, proceeds will be distributed in accordance with the liquidation preferences set forth in its organization documents unless the holders of convertible preferred stock have converted their convertible preferred stock into common stock. Convertible preferred stock are classified outside of stockholders’ equity (deficit) on the accompanying condensed consolidated balance sheets as events triggering the liquidation preferences are not solely within the Company’s control. The Company has elected not to adjust the carrying values of the convertible preferred stock to the liquidation preferences of such shares because of the uncertainty of whether or when such an event would occur. Upon the consummation of the Company’s initial public offering in July 2020, all shares of convertible preferred stock outstanding and accrued cumulative dividends automatically converted into 23,934,533 shares of common stock. Series B Convertible Preferred Stock Warrant Liability The Company has issued freestanding warrants to purchase its Series B convertible preferred stock. Freestanding warrants for the Company’s convertible preferred stock that are classified outside of permanent equity are recorded at fair value, and are subject to re-measurement paid-in paid-in re-measurement Revenue Recognition To date, the Company has derived revenue from providing research and development services on a time and materials basis to a related-party. The Company recognizes such revenues over time as services are delivered, and invoices the customer as the work is incurred in arrears. The Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of Topic 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies a performance obligation. As part of the Company’s consideration as to whether the Company has entered into a contract with a customer, it considers whether it is probable that it will collect the consideration it is entitled to in exchange for the goods and services it transfers to the customer. At contract inception, the Company assesses the goods or services promised within each contract that falls under the scope of Topic 606, determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Cost of Services for Related-Party Revenue The Company incurs costs associated with related-party services including direct labor and associated employee benefits, laboratory supplies, and other expenses. These costs are recorded in cost of services for related-party revenue as a component of total operating expenses in the accompanying condensed consolidated statements of operations and comprehensive loss. Research and Development Costs Research and development costs are expensed as incurred and consist primarily of salaries and benefits, stock-based compensation expense, lab supplies and facility costs, as well as fees paid to nonemployees and entities that conduct certain research and development activities on behalf of the Company and expenses incurred in connection with license agreements (Note 8). Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are capitalized and recorded in prepaid expenses and other current assets, and then expensed as the related goods are delivered or the services are performed. Clinical and Manufacturing Accruals The Company records accruals for estimated costs of research, preclinical studies and clinical trials, and manufacturing development, which are a significant component of research and development expenses. A substantial portion of the Company’s ongoing research and development activities are conducted by third-party service providers, including contract research organizations, or CROs, and contract manufacturing organizations, or CMOs. The Company’s contracts with CROs generally include pass-through fees such as regulatory expenses, investigator fees, travel costs and other miscellaneous costs, including shipping and printing fees. The financial terms of these contracts are subject to negotiations, which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company accrues the costs incurred under agreements with these third parties based on estimates of actual work completed in accordance with the respective agreements. The Company determines the estimated costs through discussions with internal personnel and external service providers as to the progress or stage of completion of the services and the agreed-upon fees to be paid for such services. The Company makes significant judgments and estimates in determining the accrual balance at the end of each reporting period. As actual costs become known, the Company adjusts its accruals. Although the Company does not expect its estimates to be materially different from amounts actually incurred, the Company’s understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and could result in the Company reporting amounts that are too high or too low in any particular period. To assist in its estimates the Company relies upon the receipt of timely and accurate reporting from its clinical and non-clinical Stock-based Compensation Expense The Company accounts for stock-based compensation by measuring and recognizing compensation expense for all stock-based payments made to employees, directors and non-employees Segment Reporting The Company manages its operations as a single operating segment for the purposes of assessing performance and making operating decisions. Foreign Currency Transactions The functional currency of the Company’s operation and each of its subsidiaries is U.S. dollars. All assets and liabilities denominated in a foreign currency are translated into U.S. dollars at the exchange rate prevailing on the balance sheet date. Expenses are translated at the average exchange rates prevailing during the applicable period. Foreign currency transaction gains and losses are included in the consolidated statement of operations and comprehensive loss and recorded in other expense, net, and were immaterial for the three and nine months ended September 30, 2019 and 2020, respectively. Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the condensed consolidated financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the condensed consolidated financial statement carrying amounts and tax bases of assets and liabilities using enacted tax rates in effect for the period in which the temporary differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in the condensed consolidated statements of operations and comprehensive loss in the period that includes the enactment date. The Company recognizes deferred tax assets to the extent that it believes these assets are more likely than not to be realized. In making such a determination, the Company considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning Comprehensive Loss Comprehensive loss is equal to net loss for all periods presented. Net Loss Per Share Attributable to Common Stockholders Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive given the net loss for each period presented. The Company applies the two-class two-class two-class two-class Recent Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02 Leases 2016-02). 2016-02 No. 2016-02 No. 2020-05, No. 2016-02 non-public In December 2019, the FASB issued ASU No. 2019-12, 2019-12 New Accounting Pronouncements Recently Adopted In June 2016, the FASB issued ASU No. 2016-13, In September 2018, the FASB issued ASU No. 2018-13, 2018-13 2018-13

Capital Structure

Capital Structure	Apr. 01, 2020	Sep. 30, 2020	Dec. 31, 2019
Capital Structure	3. Stockholders’ Equity The Company is authorized to issue 151 shares of common stock at $0.001 par value per share none of which are issued and outstanding as of inception on April 1, 2020.	(6) CAPITAL STRUCTURE Common Stock Common stock reserved for future issuance, on an as if converted basis, as of December 31, 2019 and September 30, 2020, consists of the following: DECEMBER 31, SEPTEMBER 30, Convertible preferred stock issued and outstanding 10,313,808 — Stock options issued and outstanding 1,183,745 4,751,589 Stock options authorized for future issuance 566,900 2,941,162 Warrants issued and outstanding 61,292 — Warrants authorized for future issuance 30,646 — Total 12,156,391 7,692,751 Convertible Preferred Stock On July 21, 2020, the Company completed its initial public offering and issued 9,775,000 shares of common stock for net proceeds of approximately $169.5 million, after deducting underwriting discounts and commissions of $13.0 million and offering-related expenses of $3.2 million. Upon the closing of the initial public offering, all shares of convertible preferred stock outstanding and accrued cumulative dividends were automatically converted into 23,934,533 shares of common stock. As of December 31, 2019, the Company’s convertible preferred stock consisted of the following (in thousands, except share amounts): DECEMBER 31, 2019 AUTHORIZED SHARES NET (1) AGGREGATE Shares designated as: Series A convertible preferred stock 9,421,633 9,297,081 $ 60,933 $ 73,571 Series B convertible preferred stock 2,145,370 1,016,727 9,430 10,014 Total 11,567,003 10,313,808 $ 70,363 $ 83,585 (1) Net proceeds are gross proceeds from the offerings net of issuance costs Preferred Stock Warrant Liability On July 21, 2020, the warrants to purchase 61,292 Series B convertible preferred stock issued to SVB and WestRiver with an exercise price of $9.4972 per share were automatically converted to warrants to purchase 61,292 shares of common stock at an exercise price of $9.4972 per share. The Company revalued the Series B convertible preferred stock warrants as of the completion of the initial public offering and reclassified the outstanding preferred stock warrant liability balance to additional paid-in re-measurement On August 17, 2020, SVB and WestRiver delivered the Notice of Exercise to net exercise 61,292 warrants at an exercise price of $9.4972 per share. Accordingly, the Company issued 48,932 shares of the Company’s common stock. Dividends Cumulative dividends of 6.0% per annum of the original issue price for each preferred stock series are payable when and as declared by the Company’s Board of Directors, or Board of Directors, upon the occurrence of a liquidation event or upon a contingent mandatory conversion of the preferred stock in connection with a qualified initial public offering as described below. The Series A original issue price is $6.58, and the Series B and Series C original issue price is $9.4972. The original issue price is subject to adjustment in the event of any share dividend, share split, combination, consolidation or other recapitalization. The dividends shall accrue from day to day from the issue date of such preferred stock whether or not declared and shall be cumulative. In addition, the preferred stockholders participate on an as-converted
Predecessor Company
Capital Structure			(5) CAPITAL STRUCTURE Ordinary Shares In 2015, in conjunction with the founding of the Company, 2,127,460 ordinary shares were issued to the founders, or Founder Stock, at a price of $0.033 per share. These shares are subject to repurchase at the option of the Company at a price that is the lower of (i) the original issuance price or (ii) the fair market value as of the date of repurchase, in the event that the founders’ employment is terminated either voluntarily or involuntarily. Such repurchase rights generally lapse over a period of four years from the date the Founder Stock was issued. As of December 31, 2018, and December 31, 2019, there were 113,864 and no founder shares subject to repurchase, respectively. See Note 6 for Founder Stock activity for the years ended December 31, 2018 and December 31, 2019. Ordinary shares reserved for future issuance, on an as if converted basis, as of December 31, 2018 and December 31, 2019, consists of the following: DECEMBER 31, 2018 2019 Convertible preferred shares, issued and outstanding 9,297,081 10,313,808 Share options, issued and outstanding 864,819 1,183,745 Share options, authorized for future issuance 73,015 566,900 Warrants, issued and outstanding — 61,292 Warrants, authorized for future issuance — 30,646 Total 10,234,915 12,156,391 Convertible Preferred Shares As of December 31, 2018 and December 31, 2019, the Company’s convertible preferred shares consisted of the following (in thousands, except share amounts): DECEMBER 31, 2018 AUTHORIZED SHARES NET (1) AGGREGATE Shares designated as: Series A convertible preferred shares 9,421,633 9,297,081 $ 60,933 $ 69,863 Total 9,421,633 9,297,081 $ 60,933 $ 69,863 DECEMBER 31, 2019 AUTHORIZED SHARES NET (1) AGGREGATE Shares designated as: Series A convertible preferred shares 9,421,633 9,297,081 $ 60,933 $ 73,571 Series B convertible preferred shares 2,145,370 1,016,727 9,430 10,014 Total 11,567,003 10,313,808 $ 70,363 $ 83,585 (1) Net proceeds are gross proceeds from the offerings net of issuance costs. In May 2015, the Company entered into a Series A Preferred Share Purchase Agreement, or Series A Agreement, with certain existing investors, employees, and new investors, or collectively, the Series A Investors. Under the terms of the Series A Agreement, the Company authorized the sale and issuance of up to 5,470,625 of the Company’s Series A convertible preferred shares. The purchase and sale of the Series A convertible preferred shares could be sold in one or more closings in accordance with the Series A Agreement. In March 2017, the Company entered into a convertible promissory note purchase agreement, or the Note Purchase Agreement, with certain existing investors, employees and new investors, or collectively, the Promissory Note Investors. Under the terms of the Note Purchase Agreement, the Company issued promissory notes in the aggregate principal amount of $25.0 million that are convertible into Series A convertible preferred shares to the Promissory Note Investors. In 2015 and 2016, the Company issued a total of 5,470,612 Series A convertible preferred shares to investors at $6.58 per share for cash proceeds of $34.8 million. In September 2017, the Company issued a total of 3,826,469 Series A convertible preferred shares for cash proceeds of $1.2 million pursuant to the conversion of outstanding convertible promissory notes. The gross proceeds of $37.2 million were reduced by total issuance costs incurred of $0.2 million. In May 2019, the Company entered into a Series B Preferred Share Purchase Agreement or the Series B Agreement, with certain existing investors, employees and new investors, or collectively, the Series B Investors. Under the terms of the Series B Agreement, the Company authorized the sale and issuance of up to 2,145,370 of the Company’s Series B convertible preferred shares at a purchase price of $9.4972 per share. The purchase and sale of the Series B convertible preferred shares could be sold in one or more closings in accordance with the Series B Agreement. As of December 31, 2019, a total of 1,016,727 shares had been purchased with gross proceeds of $9.6 million. The gross proceeds of $9.6 million were reduced by total issuance costs incurred of $0.2 million. The rights, preferences and privileges of the Series A and Series B convertible preferred shares, or Preferred Shares, as of December 31, 2019 are as follows: Dividend Provisions as-converted Liquidation pro-rata pro-rata Voting Rights two-third as-converted Optional Conversion at Holders’ Option non-assessable Contingent Mandatory Conversion non-U.S. Down-Round Antidilution Protection

Subsequent Events

Subsequent Events	Apr. 01, 2020	Dec. 31, 2019
Subsequent Events	4. Subsequent Events Authorized Share Increase On April 1, 2020 (subsequent to inception), the Company increased its authorized shares from 151 to 1,519,618,271 shares of common stock and 9,297,100 Series A convertible preferred stock, 1,108,675 of Series B convertible preferred stock and 11,055,981 of Series C convertible preferred stock. Equity Incentive Plan On April 1, 2020 (subsequent to inception), the board of directors approved a new equity incentive plan, or the 2020 Equity Incentive Plan or the Plan, that replaced the 2015 Share Award Scheme. The Plan is for employees, non-employee Reorganization On April 1, 2020 (subsequent to inception), the Company consummated the internal reorganization whereby the Company issued and sold to the existing shareholders of ALX Oncology Limited an aggregate of 3,166,946 shares of our common stock at purchase prices per share ranging from $0.007 to $1.91, an aggregate of 9,297,081 shares of our Series A convertible preferred stock at a purchase price per share of $6.58, an aggregate of 1,016,727 shares of our Series B convertible preferred stock at a purchase price per share of $9.4972 and an aggregate of 11,055,966 shares of our Series C convertible preferred stock at a purchase price per share of $9.4972, in exchange for promissory notes with an aggregate principal amount of $176.3 million. The Company also acquired 525,000,000 ordinary shares of ALX Oncology Limited in exchange for the promissory notes that were acquired in connection with such issuance and sale of the Company’s capital stock. Reverse Stock Split On July 8, 2020, the Company’s board of directors approved an amendment to the Company’s certificate of incorporation to effect a 1-for-6.5806
Predecessor Company
Subsequent Events		(13) SUBSEQUENT EVENTS Series C Preferred Share Issuance In February 2020, the Company entered into a Series C Preferred Share Purchase Agreement, or the Series C Agreement, with certain existing investors, employees and new investors, or collectively, the Series C Investors. Under the terms of the Series C Agreement, the Company authorized the sale and issuance of up to 11,055,981 Series C convertible preferred shares at a purchase price of $9.4972 per share. To date, all authorized Series C convertible preferred shares have been purchased with gross proceeds of $105.0 million. Reorganization On April 1, 2020, the Company completed an internal reorganization transaction pursuant to which ALX Oncology Limited became a wholly-owned subsidiary ALX Oncology Holdings Inc., a newly formed Delaware corporation. As part of the transaction, all of the equity, option and warrant holders of ALX Oncology Limited became equity, option and warrant holders of ALX Oncology Holdings Inc., holding the same number of corresponding shares, options and/or warrants in ALX Oncology Holdings Inc., as they did in the Company immediately prior to the reorganization. Reverse Stock Split On July 8, 2020, the Company’s board of directors approved an amendment to ALX Oncology Holdings Inc.’s certificate of incorporation to effect a 1-for-6.5806

Organization and summary of sig

Organization and summary of significant accounting policies	12 Months Ended
	Dec. 31, 2019
Predecessor Company
Organization and summary of significant accounting policies	(1) ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Organization Alexo Therapeutics Limited, or the Company, was initially incorporated in Ireland on March 13, 2015 and changed its name to ALX Oncology Limited on October 11, 2018. The Company is a clinical-stage immuno-oncology company focused on helping patients fight cancer by developing therapies that block the CD47 checkpoint pathway and bridge the innate and adaptive immune system. The Company owns a direct subsidiary, ALX Oncology Inc., incorporated in the United States, as well as a direct subsidiary incorporated in Malta, Alexo International Holdings Ltd. The Company also has two indirect subsidiaries, Alexo Therapeutics International, incorporated in the Cayman Islands, which is a wholly-owned subsidiary of Alexo International Holdings Ltd. and Sirpant Therapeutics, incorporated in the Cayman Islands, which is a wholly-owned subsidiary of Alexo Therapeutics International, collectively, the Subsidiaries. The Company completed an internal reorganization transaction in April 2020, pursuant to which ALX Oncology Limited became a wholly-owned subsidiary of ALX Oncology Holdings Inc., a newly formed Delaware corporation. As part of the transaction, all of the equity, option and warrant holders of ALX Oncology Limited became equity, option and warrant holders of ALX Oncology Holdings Inc., holding the same number of corresponding shares, options and/or warrants in ALX Oncology Holdings Inc., as they did in the Company immediately prior to the reorganization (Note 13). Basis of Preparation These consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or U.S. GAAP. Principles of Consolidation All intercompany balances and transactions have been eliminated in consolidation. Unaudited Pro Forma Information Immediately prior to the completion of this offering, all outstanding convertible preferred shares will automatically convert into ordinary shares. Unaudited pro forma basic and diluted net loss per share has been computed to give effect to the conversion of all outstanding convertible preferred shares and cumulative dividends on the convertible preferred shares into ordinary shares. The unaudited pro forma net loss per share does not include the shares expected to be sold and related proceeds to be received from the initial public offering. Need for Additional Capital Since commencing operations, none of the Company’s product candidates have received marketing approval from the U.S. Food and Drug Administration, or FDA, or any other federal, state, local or foreign governmental or regulatory authority and therefore the Company has not generated any revenue from drug product sales. The Company had an accumulated deficit of $72.8 million as of December 31, 2019 and management does not expect to experience positive cash flows in the foreseeable future. Based on management’s current plans, management believes cash of $9.0 million as of December 31, 2019, along with the $105.0 million of gross proceeds from the issuance of Series C convertible preferred shares in February 2020 (Note 13), are sufficient to fund operations through at least one year from the date of the issuance of these consolidated financial statements. Management expects to incur additional losses in the future to conduct product candidate research and development and to conduct pre-commercialization out-license 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 reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. On an ongoing basis, management evaluates its estimates, including those related to the estimated useful lives of long-lived assets, clinical trial accruals, fair value of assets and liabilities, Series B convertible preferred shares warrant liability, term loan compound derivative liability, term loan, valuation of ordinary shares, income taxes and share-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates. Cash The Company holds its cash in checking and interest-bearing accounts. Concentration of Credit Risk and Other Risks and Uncertainties Financial instruments that potentially subject the Company to a concentration of credit risk consist primarily of cash. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash. The Company has not experienced any losses on its deposits of cash. The Company’s future results of operations involve a number of other risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, uncertainty of results of clinical trials and reaching milestones, uncertainty of regulatory approval of the Company’s potential product candidates, uncertainty of market acceptance of the Company’s product candidates, competition from substitute products and larger companies, securing and protecting proprietary technology, strategic relationships and dependence on key individuals or sole-source suppliers. The Company’s product candidates require approvals from the FDA and comparable foreign regulatory agencies prior to commercial sales in their respective jurisdictions. There can be no assurance that any product candidates will receive the necessary approvals. If the Company was denied approval, approval was delayed or the Company was unable to maintain approval for any product candidate, it could have a materially adverse impact on the Company. Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation of property and equipment is provided using the straight-line method over the estimated useful lives of the assets (Note 3). Upon sale or retirement of assets, the cost and related accumulated depreciation or amortization are removed from the consolidated balance sheet and the resulting gain or loss is reflected in the consolidated statement of operations and comprehensive loss. Maintenance and repairs are charged to the consolidated statement of operations and comprehensive loss as incurred. The useful lives of the property and equipment are as follows: Research and development equipment 5 years Furniture and office equipment 5 years Computer equipment 3 years Software 3 years Leasehold improvements Shorter of 7 years or remaining of lease term Impairment of Long-Lived Assets The Company reviews property and equipment for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amount to the future undiscounted net cash flows which the asset or asset group are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured as the amount by which the carrying amount of the assets exceeds its fair value. Fair value is determined using various valuation techniques including discounted cash flow models, quoted market values and third-party independent appraisals, as considered necessary. There were no impairment charges recognized in the years ended December 31, 2018 and December 31, 2019. Fair Value of Financial Instruments The Company applies fair value accounting for all financial assets and liabilities and nonfinancial assets and liabilities that are required to be recognized or disclosed at fair value in the consolidated financial statements. The Company defines fair value as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Where observable prices or inputs are not available valuation models are applied. These valuation techniques involve some level of management estimation and judgment, the degree of which is dependent on the price transparency for the instruments or market and the instruments’ complexity. The Company’s financial instruments consist of cash, accounts receivable, accounts payable, the term loan compound derivative liability and the Series B convertible preferred shares warrant liability. The term loan compound derivative liability and the Series B convertible preferred shares warrant liability are re-measured Term Loan The Company accounts for the Loan and Security Agreement, dated as of December 20, 2019, with Silicon Valley Bank, and WestRiver Innovation Lending Fund VIII, LP, collectively as lenders, and Silicon Valley Bank, as administrative agent and collateral agent, as a liability measured at net proceeds less debt discount and is accreted to the face value of the term loan over its expected term using the effective interest method. The Company considers whether there are any embedded features in its debt instruments that require bifurcation and separate accounting as derivative financial instruments pursuant to Accounting Standards Codification, or ASC, Topic 815, Derivatives and Hedging Convertible Preferred Shares The Company records convertible preferred shares net of issuance costs on the dates of issuance, which represents the carrying value. In the event of a change of control of the Company, proceeds will be distributed in accordance with the liquidation preferences set forth in its Constitution unless the holders of convertible preferred shares have converted their convertible preferred shares into ordinary shares. Convertible preferred shares are classified outside of shareholders’ deficit on the accompanying consolidated balance sheets as events triggering the liquidation preferences are not solely within the Company’s control. The Company has elected not to adjust the carrying values of the convertible preferred shares to the liquidation preferences of such shares because of the uncertainty of whether or when such an event would occur. Series B Convertible Preferred Shares Warrant Liability The Company has issued freestanding warrants to purchase its Series B convertible preferred shares. Freestanding warrants for the Company’s convertible preferred shares that are classified outside of permanent equity are recorded at fair value, and are subject to re-measurement paid-in Revenue Recognition To date, the Company has derived revenue from providing research and development services on a time and materials basis to a related-party. The Company recognizes such revenues over time as services are delivered, and invoices the customer as the work is incurred in arrears. Effective January 1, 2018, the Company adopted ASC Topic 606, Revenue from Contracts with Customers To determine revenue recognition for arrangements that the Company determines are within the scope of Topic 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies a performance obligation. As part of the Company’s consideration as to whether the Company has entered into a contract with a customer, it considers whether it is probable that it will collect the consideration it is entitled to in exchange for the goods and services it transfers to the customer. At contract inception, the Company assesses the goods or services promised within each contract that falls under the scope of Topic 606, determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated based on their standalone selling price to the respective performance obligation when (or as) the performance obligation is satisfied. Cost of Services for Related-Party Revenue The Company incurs costs associated with related-party services including direct labor and associated employee benefits, laboratory supplies, and other expenses. These costs are recorded in cost of services for related-party revenue as a component of total operating expenses in the accompanying consolidated statements of operations and comprehensive loss. Research and Development Costs Research and development costs are expensed as incurred and consist primarily of salaries and benefits, share-based compensation expense, lab supplies and facility costs, as well as fees paid to nonemployees and entities that conduct certain research and development activities on behalf of the Company and expenses incurred in connection with license agreements (Note 9). Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are capitalized and recorded in prepaid expenses and other current assets, and then expensed as the related goods are delivered or the services are performed. Clinical and Manufacturing Accruals The Company records accruals for estimated costs of research, preclinical studies and clinical trials, and manufacturing development, which are a significant component of research and development expenses. A substantial portion of the Company’s ongoing research and development activities are conducted by third-party service providers, including contract research organizations, or CROs, and contract manufacturing organizations, or CMOs. The Company’s contracts with CROs generally include pass-through fees such as regulatory expenses, investigator fees, travel costs and other miscellaneous costs, including shipping and printing fees. The financial terms of these contracts are subject to negotiations, which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company accrues the costs incurred under agreements with these third parties based on estimates of actual work completed in accordance with the respective agreements. The Company determines the estimated costs through discussions with internal personnel and external service providers as to the progress or stage of completion of the services and the agreed-upon fees to be paid for such services. The Company makes significant judgments and estimates in determining the accrual balance at the end of each reporting period. As actual costs become known, the Company adjusts its accruals. Although the Company does not expect its estimates to be materially different from amounts actually incurred, the Company’s understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and could result in the Company reporting amounts that are too high or too low in any particular period. To assist in its estimates the Company relies upon the receipt of timely and accurate reporting from information provided as part of its clinical and non-clinical Share-Based Compensation Expense The Company accounts for share-based compensation by measuring and recognizing compensation expense for all share-based payments made to employees, directors and non-employees Segment Reporting The Company manages its operations as a single operating segment for the purposes of assessing performance and making operating decisions. All of the Company’s assets are maintained in the United States and Ireland. Foreign Currency Transactions The functional currency of the Company’s operation and each of its subsidiaries is U.S. dollars. All assets and liabilities denominated in a foreign currency are translated into U.S. dollars at the exchange rate prevailing on the balance sheet date. Expenses are translated at the average exchange rates prevailing during the applicable period. Foreign currency transaction gains and losses are included in the consolidated statement of operations and comprehensive loss and recorded in other income (expense), net, and was immaterial for the years ended December 31, 2018 and December 31, 2019, respectively. Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the consolidated financial statement carrying amounts and tax bases of assets and liabilities using enacted tax rates in effect for the period in which the temporary differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in the consolidated statements of operations and comprehensive loss in the period that includes the enactment date. The Company recognizes deferred tax assets to the extent that it believes these assets are more likely than not to be realized. In making such a determination, the Company considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning The Company recognizes benefits of uncertain tax positions if it is more likely than not that such positions will be sustained upon examination based solely on their technical merits, as the largest amount of benefit that is more likely than not to be realized upon the ultimate settlement. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit. Net Loss Per Share Attributable to Ordinary Shareholders Basic net loss per share is calculated by dividing the net loss attributable to ordinary shareholders by the weighted-average number of ordinary shares outstanding during the period, without consideration for ordinary share equivalents. Net loss attributable to ordinary shareholders is calculated by adjusting net loss of the Company for cumulative preferred share dividends. Diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive given the net loss for each period presented. The Company applies the two-class two-class two-class two-class Unaudited Pro Forma Net Loss Per Share Attributable to Ordinary Shareholders In contemplation of an initial public offering, or IPO, the Company has presented unaudited pro forma basic and diluted net loss per share attributable to ordinary shareholders for the year ended December 31, 2019. Unaudited pro forma basic net loss per share attributable to ordinary shareholders as of December 31, 2019 is computed to give effect to adjustments to the denominator in the pro forma basic and diluted net loss per share calculation to reflect the conversion of all of the Company’s outstanding convertible preferred shares and cumulative dividends into 11,253,839 ordinary shares, as if the conversion had occurred as of the beginning of the period or the original date of issuance, if later. Unaudited pro forma diluted net loss attributable to ordinary shareholders is the same as unaudited pro forma basic net loss per share attributable to ordinary shareholders for the period as the impact of any potentially dilutive securities was anti-dilutive, which has been computed to give effect to the adjustment noted above. The pro forma net loss per share attributable to ordinary shareholders does not include proceeds to be received from nor does it include shares expected to be sold in the assumed IPO. Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board, or FASB, or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s financial position or results of operations upon adoption. In February 2016, the FASB issued ASU No. 2016-02 Leases 2016-02). 2016-02 No. 2016-02 No. 2019-10, No. 2016-02 non-public In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses No. 2020-02 In December 2019, the FASB issued ASU No. 2019-12, Income Taxes 2019-12 New Accounting Pronouncements Recently Adopted In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows 2016-18 In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share Distinguishing Liabilities from Equity No. 2017-11 2017-11

Fair Value Of Financial Instrum

Fair Value Of Financial Instruments	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Fair Value of Financial Instruments	(3) FAIR VALUE OF FINANCIAL INSTRUMENTS The fair value of the Company’s financial assets and liabilities are determined in accordance with the fair value hierarchy established in ASC Topic 820, Fair Value Measurements and Disclosures. ASC Topic 820 defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value hierarchy of ASC Topic 820 requires an entity to maximize the use of observable inputs when measuring fair value and classifies those inputs into three levels: Level 1—Observable inputs, such as quoted prices in active markets Level 2—Inputs, other than the quoted prices in active markets, which are observable either directly or indirectly such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the instrument’s anticipated life Level 3—Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions The Company’s financial instruments consist of cash and cash equivalents, receivables due from related-party, accounts payable, the term loan compound derivative liability and the Series B convertible preferred stock warrant liability. Cash and cash equivalents are reported at their respective fair values on the Company’s condensed consolidated balance sheets. Where quoted prices are available in an active market, securities are classified as Level 1. The Company classifies money market funds as Level 1. When quoted market prices are not available for the specific security, then the Company estimates fair value by using quoted prices for identical or similar instruments in markets that are not active and model-based valuation techniques for which all significant inputs are observable in the market or can be corroborated by observable market data for substantially the full term of the assets. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs obtained from various third-party data providers, including but not limited to benchmark yields, reported trades and broker/dealer quotes. Where applicable the market approach utilizes prices and information from market transactions for similar or identical assets. The Company measures its Series B convertible preferred stock warrant liability and term loan compound derivative liability at fair value on a recurring basis and these are classified as Level 3 liabilities. The fair value of the Series B convertible preferred stock warrant liability was determined using an option-pricing model. The Company revalued the Series B convertible preferred stock warrants as of the completion of the initial public offering and reclassified the outstanding preferred stock warrant liability balance to additional paid-in re-measurement The following table sets forth the Company’s financial liabilities that are measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): AS OF DECEMBER 31, 2019 LEVEL 1 LEVEL 2 LEVEL 3 FAIR VALUE Financial liabilities Non-current Compound derivative liability $ — — 51 $ 51 Warrant liability $ — — 361 $ 361 AS OF SEPTEMBER 30, 2020 LEVEL 1 LEVEL 2 LEVEL 3 FAIR VALUE Financial assets Cash equivalents Money market funds $ 90,114 — — $ 90,114 Financial liabilities Non-current Compound derivative liability $ — — 43 $ 43 The following table is a reconciliation of all financial liabilities measured at fair value using Level 3 unobservable inputs (in thousands): WARRANT COMPOUND Fair value at December 31, 2019 $ 361 $ 51 Change in fair value 658 (8 ) Reclassification to equity (1,019 ) — Fair value at September 30, 2020 $ — $ 43 The Company did not have any outstanding financial assets or liabilities to be re-measured There were no transfers of assets or liabilities between the fair value measurement levels during the year ended December 31, 2019 and the nine months ended September 30, 2020. The carrying values of the Company’s financial instruments, such as accounts payable and accrued expenses and other current liabilities, approximate fair value due to the short-term nature of these items. Term Loan The estimated fair value of the Term Loan was $6.1 million as of September 30, 2020, which approximates the carrying value and is classified as Level 3. The Company utilized a market yield analysis and income approach to estimate a value for the Term Loan. The key valuation assumptions used consist of the discount rate of 12.0% and the probability of the occurrence of a change in control event of 20.0%.
Predecessor Company
Fair Value of Financial Instruments		(2) FAIR VALUE OF FINANCIAL INSTRUMENTS The fair value of the Company’s financial assets and liabilities are determined in accordance with the fair value hierarchy established in ASC Topic 820, Fair Value Measurements and Disclosures Level 1 Level 2 Level 3 The Company measures its Series B convertible preferred shares warrant liability and term loan compound derivative liability at fair value on a recurring basis and these are classified as Level 3 liabilities. The fair value of the Series B preferred shares warrant liability was determined using an option-pricing model. The Company calculated the fair value of the term loan compound derivative liability by computing the difference between the fair value of the term loan with the compound derivative using the “with and without” method under the income approach, and the fair value of the term loan without the compound derivative. The valuation methodology and underlying assumptions are discussed further in Note 4. The following table sets forth the Company’s financial liabilities that are measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): AS OF DECEMBER 31, 2019 LEVEL 1 LEVEL 2 LEVEL 3 FAIR VALUE Financial liabilities Long term liabilities Compound derivative liability $ — — 51 $ 51 Warrant liability $ — — 361 $ 361 The following tables are a reconciliation of all financial liabilities measured at fair value using Level 3 unobservable inputs (in thousands): WARRANT COMPOUND Balance as of December 31, 2018 $ — $ — Additions 361 51 Change in market value — — Balance as of December 31, 2019 $ 361 $ 51 The Company did not have any outstanding financial liabilities to be re-measured Term Loan The estimated fair value of the Term Loan was $5.7 million as of December 31, 2019 which approximates the carrying value and is classified as Level 3. The Company utilized a market yield analysis and income approach to estimate a value for the Term Loan. The key valuation assumptions used consist of the discount rate of 14.5% and the probability of the occurrence of a change in control event of 10.0%.

Balance Sheet Components

Balance Sheet Components	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Balance Sheet Components	(4) BALANCE SHEET COMPONENTS Property and Equipment, Net The following table presents the components of property and equipment, net as of December 31, 2019 and September 30, 2020 (in thousands): DECEMBER 31, SEPTEMBER 30, Computer hardware and software $ 146 $ 74 Machinery and equipment 1,698 40 Furniture and fixtures 36 9 Leasehold improvements 429 19 2,309 142 Less: accumulated depreciation and amortization (1,449 ) (97 ) Total property and equipment, net $ 860 $ 45 Depreciation and amortization expense was $0.1 million for the three months ended September 30, 2019, and $0.3 million and $0.2 million for the nine months ended September 30, 2019 and 2020, respectively. Depreciation and amortization expense for the three months ended September 30, 2020 was nominal. At June 30, 2020, certain lab equipment and other assets for an aggregated net book value of $0.6 million relating to the asset transfer with Tallac Therapeutics, Inc. (formerly known as Tollnine, Inc., or Tollnine), or Tallac Therapeutics, a related party (Note 9), met the criteria as assets held for sale. Those assets were reported at the lower of carrying value or fair value less costs to sell. In July 2020, the Company received $0.6 million cash in exchange for the transfer of such assets. Accrued Expenses and Other Current Liabilities The following table presents the components of accrued expenses and other current liabilities as of December 31, 2019 and September 30, 2020 (in thousands): DECEMBER 31, SEPTEMBER 30, Accrued professional fees $ 122 $ 345 Accrued compensation 924 1,124 Accrued clinical and nonclinical study costs — 629 Accrued contract manufacturing 53 867 Other 137 240 Total accrued expenses and other current liabilities $ 1,236 $ 3,205
Predecessor Company
Balance Sheet Components		(3) BALANCE SHEET COMPONENTS Property and Equipment, Net The following table presents the components of property and equipment, net as of December 31, 2018 and December 31, 2019 (in thousands): DECEMBER 31, 2018 2019 Computer hardware and software $ 117 $ 146 Machinery and equipment 1,374 1,698 Furniture and fixtures 36 36 Leasehold improvements 429 429 Construction in progress 20 — 1,976 2,309 Less: accumulated depreciation and amortization (1,020 ) (1,449 ) Total property and equipment, net $ 956 $ 860 Depreciation and amortization expense was approximately $0.4 million for both years ended December 31, 2018 and December 31, 2019. Accrued Expenses and Other Current Liabilities The following table presents the components of accrued expenses and other current liabilities as of December 31, 2018 and December 31, 2019 (in thousands): DECEMBER 31, 2018 2019 Payroll and related liabilities $ 62 $ 60 Accrued bonus 745 864 Accrued legal costs 98 122 Early exercise liability 105 27 Other 166 163 Total accrued expenses and other current liabilities $ 1,176 $ 1,236

Term Loan

Term Loan	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Term Loan	(5) TERM LOAN The Company’s wholly-owned subsidiaries Alexo Therapeutics International and Sirpant Therapeutics, as borrowers, entered into a Loan and Security Agreement, or the Loan Agreement, dated as of December 20, 2019, with SVB and WestRiver, collectively as lenders, and SVB, as administrative agent and collateral agent. As a result of the internal reorganization, in May 2020 the Company entered into a Joinder and First Amendment to the Loan and Security Agreement, or the Joinder Amendment, and Amended and Restated Warrants to Purchase Stock, or the Amended Warrants. The purpose for entering into the Joinder Amendment was to add the newly established ALX Oncology Holdings Inc. as additional borrower to the Term Loan. Concurrently, the Company modified the Amended Warrants to change the issuer from ALX Oncology Limited to ALX Oncology Holdings Inc. The Company accounted for the First Amendment to the Loan and Security Agreement as a modification. The Loan Agreement provides for term loans in an aggregate principal amount of up to $10.0 million funded in two tranches, subject to the satisfaction of a certain milestone. The first tranche, in the amount of $6.0 million, was funded on the closing date of the Loan Agreement in December 2019. A second tranche of $4.0 million was available on or before March 31, 2020, upon the Company’s achievement of an equity financing resulting in net cash proceeds in an amount of at least $30.0 million to the Company. The Company elected not to draw down on the second tranche, which is no longer available. The loans under the Loan Agreement bear interest at a floating per annum interest rate equal to the greater of 7.0% or 2.0% plus the prime rate as reported in The Wall Street Journal. The Wall Street Journal prime rate was 3.25% as of September 30, 2020. Therefore, the rate applicable to the Company as of September 30, 2020 was 7.0%. The Company is required to make interest-only payments for the first 12 months after the closing of the Loan Agreement, followed by consecutive equal monthly payments of principal and interest commencing on January 1, 2021 and continuing through the maturity date of September 1, 2022. The Loan Agreement also provides for a final payment equal to 6.0% multiplied by the aggregate principal amount of the term loans funded, which is due on the maturity date, upon the acceleration of the term loans, or upon prepayment of the term loans. If the Company elects to prepay the term loans, there is also a prepayment fee of between 1.0% and 3.0% of the principal amount being prepaid depending on the timing and circumstances of prepayment. In conjunction with the Loan Agreement, the Company has issued warrants to purchase 61,292 Series B convertible preferred stock to SVB and WestRiver with an exercise price of $9.4972 per share. Following the Company’s initial public offering, these warrants were automatically converted to warrants to purchase 61,292 shares of common stock at an exercise price of $9.4972 per share. The estimated fair value of the warrants at the date of issuance was approximately $0.4 million. The Company revalued the Series B convertible preferred stock warrants as of the completion of the initial public offering and reclassified the outstanding preferred stock warrant liability balance of $1.0 million to additional paid-in re-measurement The loans under the Loan Agreement are secured by substantially all of the Company’s assets, except the Company’s intellectual property, which is the subject of a negative pledge. The Company determined that certain loan features were embedded derivatives requiring bifurcation and separate accounting. Those embedded derivatives were bundled together as a single, compound embedded derivative and then bifurcated and accounted for separately from the host contract. The Company recorded a term loan compound derivative liability of approximately $51,000 which will be marked-to-market re-measured non-current The fair value of Series B convertible preferred stock warrant liability at issuance, fair value of embedded derivatives which were bifurcated and other debt issuance costs have been treated as debt discounts on the Company’s condensed consolidated balance sheet and together with the final payment are being amortized to interest expense throughout the life of the term loan using the effective interest rate method. As of September 30, 2020, there were unamortized issuance costs and debt discounts of $0.2 million, which were recorded as a direct deduction from the term loan on the condensed consolidated balance sheet. Interest expense for the term loan was $0.3 million and $0.7 million for the three and nine months ended September 30, 2020, respectively. The following table presents future payments of principal and interest as of September 30, 2020 (in thousands): SEPTEMBER 30, 2020 (remaining three months) $ 106 2021 3,743 2022 3,007 6,856 Less: amount representing interest $ (496 ) Less: amount representing final payment (360 ) Term loan, principal amount 6,000 Less: unamortized issuance costs and debt discounts (240 ) Less: current portion (2,571 ) Non-current $ 3,189
Predecessor Company
Term Loan		(4) TERM LOAN The Company and its wholly-owned subsidiaries Alexo Therapeutics International and Sirpant Therapeutics, as borrowers, entered into a Loan and Security Agreement, or the Loan Agreement, dated as of December 20, 2019, with Silicon Valley Bank, or SVB, and WestRiver Innovation Lending Fund VIII, LP, or WestRiver, collectively as lenders, and SVB, as administrative agent and collateral agent. The Loan Agreement provides for term loans in an aggregate principal amount of up to $10.0 million funded in two tranches, subject to the satisfaction of a certain milestone. The first tranche, in the amount of $6.0 million, was funded on the closing date of the Loan Agreement in December 2019. A second tranche of $4.0 million was available on or before March 31, 2020, upon the Company’s achievement of an equity financing resulting in net cash proceeds in an amount of at least $30.0 million to the Company. The Company elected not to draw down on the second tranche, which is no longer available. The loans under the Loan Agreement bear interest at a floating per annum interest rate equal to the greater of 7.0% or 2.0% plus the prime rate as reported in The Wall Street Journal. The Wall Street Journal prime rate was 4.75% as of December 31, 2019. Therefore, the rate applicable to the Company as of December 31, 2019 was 7.0%. The Company is required to make interest-only payments for the first 12 months after the closing of the Loan Agreement, followed by consecutive equal monthly payments of principal and interest commencing on January 1, 2021 and continuing through the maturity date of September 1, 2022. The Loan Agreement also provides for a final payment equal to 6.0% multiplied by the aggregate principal amount of the term loans funded, which is due on the maturity date, upon the acceleration of the term loans, or upon prepayment of the term loans. If the Company elects to prepay the term loans, there is also a prepayment fee of between 1.0% and 3.0% of the principal amount being prepaid depending on the timing and circumstances of prepayment. In conjunction with the Loan Agreement, the Company has issued warrants to purchase 61,292 Series B convertible preferred shares to SVB and WestRiver with an exercise price of $9.4972 per share. The estimated fair value of the warrants at the date of issuance was approximately $0.4 million. The fair value of the Series B convertible preferred shares warrant liability was determined using the Black-Scholes option-pricing model. As of December 20, 2019, the various assumptions used in the option-pricing model were time to liquidity of 2.0 to 10.0 years, volatility of 85.5%, risk-free rate of 1.7% and equity value of $345.0 million. It was recorded at its fair value at inception and is being re-measured The loans under the Loan Agreement are secured by substantially all of the Company’s assets, except the Company’s intellectual property, which is the subject of a negative pledge. The Company determined that certain loan features were embedded derivatives requiring bifurcation and separate accounting. Those embedded derivatives were bundled together as a single, compound embedded derivative and then bifurcated and accounted for separately from the host contract. The Company recorded a term loan compound derivative liability of approximately $51,000 which will be marked-to-market re-measured The fair value of Series B convertible preferred shares warrant liability at issuance, fair value of embedded derivatives which were bifurcated and other debt issuance costs have been treated as debt discounts on the Company’s consolidated balance sheet and together with the final payment are being amortized to interest expense throughout the life of the term loan using the effective interest rate method. As of December 31, 2019, there were unamortized issuance costs and debt discounts of $0.6 million which were recorded as a direct deduction from the term loan on the consolidated balance sheet. Interest expense for the term loan was immaterial for the year ended December 31, 2019. For future payments of principal and interest as of December 31, 2019 is as follows. YEAR ENDING DECEMBER 31: 2020 $ 401 2021 3,743 2022 3,007 7,151 Less: amount representing interest $ (791 ) Less: amount representing final payment (360 ) Long-term debt, gross 6,000 Less: unamortized issuance costs and debt discounts (579 ) Less: current portion — Long-term portion of term loan $ 5,421

Share-Based Compensation

Share-Based Compensation	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Share-Based Compensation	(7) STOCK-BASED COMPENSATION 2020 Amended and Restated Equity Incentive Plan On April 1, 2020, the board of directors approved a new equity incentive plan, or the 2020 Equity Incentive Plan, that replaced the 2015 Share Award Scheme. In July 2020, the Company adopted the Amended and Restated 2020 Equity Incentive Plan, or the 2020 Plan. The 2020 Plan replaced the Company’s 2020 Equity Incentive Plan and a total of 7,874,862 shares were reserved under the 2020 Plan. Stock Option Modification In connection with the transfer of employees to Tallac Therapeutics, Dr. Hong Wan, the Company’s former Chief Scientific Officer, and eight of the Company’s employees, or Transferred Employees, terminated their employment with the Company effective as of June 30, 2020 and became employees of Tallac Therapeutics effective as of July 1, 2020. The options to purchase shares of the Company’s common stock that were previously granted to the Transferred Employees will continue to vest and be exercisable subject to the Transferred Employees remaining service providers under the original terms of the award. The Company evaluated the change in status from an employee to a consultant in accordance with ASC 718. While the Company concluded that the change in status did not affect the vesting condition or the classification of the initial awards, the significant reduction in the level of services that the grantees were expected to provide under the original awards as compared to the level of services expected under the Tallac Services Agreement will no longer meet the substantive service condition requirements and therefore the compensation cost for the unvested awards was recognized immediately with no future service requirement. The Company recorded $2.3 million in stock-based compensation expenses related to the modification for the three months ended June 30, 2020. In September 2020, in connection with the resignation of the Company’s former Chief Business Officer and the entry into a consulting agreement with him, the Company evaluated the change in status from an employee to a consultant in accordance with ASC 718. While the Company concluded that the change in status did not affect the vesting condition or the classification of the initial awards, the significant reduction in the level of services that the grantee was expected to provide under the original awards as compared to the level of services expected under the consulting agreement will no longer meet the substantive service condition requirements and therefore the compensation expense for the unvested awards expected to vest during the consultancy was recognized immediately with no future service requirement. The Company recorded $0.2 million in stock-based compensation expenses related to the modification for the three months ended September 30, 2020. Stock-based Compensation Expense Total stock-based compensation expense recognized in the condensed consolidated statements of operations and comprehensive loss was as follows (in thousands): THREE MONTHS ENDED NINE MONTHS ENDED 2019 2020 2019 2020 Research and development $ 25 $ (359 ) $ 79 $ 2,008 General and administrative 10 1,048 24 1,685 Cost of services for related-party revenue 51 — 119 — $ 86 $ 689 $ 222 $ 3,693
Predecessor Company
Share-Based Compensation		(6) SHARE-BASED COMPENSATION During 2015, the Company adopted an equity compensation plan, the 2015 Share Award Scheme, or the Plan, for eligible employees, officers, directors, advisors, and consultants. The Plan provides for the grant of incentive and non-statutory non-statutory The terms of the share option agreements, including vesting requirements, are determined by the Board of Directors, subject to the provisions of the Plan. The term of the options generally expire, upon the earliest of (i) termination of continuous service for cause (ii) three months after the termination of continuous service for reasons other than cause, death or disability (iii) twelve months after the termination of continuous service due to disability (iv) eighteen months after the employee’s death if the employee died during the period of continuous service (v) expiration date in the grant notice or (vi) the day before the tenth anniversary of the date of grant. The exercise price of the incentive share options must equal at least the fair market value of the share on the date of grant. All awards that are canceled, forfeited or expired are returned to the Plan and are available for grant in conjunction with the issuance of new awards. Share options granted are exercisable over a maximum term of 10 years from the date of grant and generally vest over an agreed service period, usually four years. Certain share options granted under the Plan provide option holders the right to elect to exercise unvested options in exchange for ordinary shares. Such unvested ordinary shares are subject to a repurchase right held by the Company at the original issuance price in the event the optionee’s service to the Company is terminated either voluntarily or involuntarily. The right lapses as the underlying repurchase right expires. These repurchase terms are considered to be a forfeiture provision. The cash received from employees for exercise of unvested options is treated as a refundable deposit and is classified as a liability on the consolidated balance sheets. At December 31, 2018 and December 31, 2019, there were 116,048 and 34,024 unvested early exercised options and the liability related to these unvested options was $0.1 million and approximately $27,000, respectively. (a) Option Activity The following table provides a summary of share option activity under the Plan and related information: OUTSTANDING OPTIONS SHARES NUMBER WEIGHTED WEIGHTED AGGREGATE (in thousands) Balance outstanding at December 31, 2017 218,322 719,527 $ 0.99 9.18 $ — Granted (187,186 ) 187,186 $ 1.85 Exercised — (6,914 ) $ 0.99 Canceled/forfeited 34,980 (34,980 ) $ 0.99 Shares repurchased 6,899 — — Balance outstanding at December 31, 2018 73,015 864,819 $ 1.17 8.54 $ 582 Authorized 818,010 Granted (341,871 ) 341,871 $ 1.91 Exercised — (5,199 ) $ 1.86 Canceled/forfeited 17,746 (17,746 ) $ 1.88 Balance outstanding at December 31, 2019 566,900 1,183,745 $ 1.37 8.06 $ 638 Exercisable at December 31, 2019 565,975 $ 1.16 7.56 $ 424 As of December 31, 2019, there was unrecognized share-based compensation expense of $0.6 million, related to unvested share options which the Company expects to recognize over a weighted-average period of 2.7 years. The aggregate intrinsic values of options outstanding and exercisable were calculated as the difference between the exercise price of the options and the estimated fair value of the Company’s ordinary shares as determined by the Board of Directors as of December 31, 2018 and December 31, 2019. The total intrinsic value of options exercised during the years ended December 31, 2018 and 2019 were immaterial. Compensation cost for share options granted is based on the grant-date fair value estimated and is recognized over the vesting period of the applicable option on a straight-line basis. The weighted-average grant-date fair value per share for share options granted during the years ended December 31, 2018 and December 31, 2019 was $1.14 and $1.27, respectively. The total fair value of options that vested during the years ended December 31, 2018 and December 31, 2019 was approximately $0.1 million and $0.3 million, respectively. Share-based compensation expense includes share options granted to employees and nonemployees and has been reported in the Company’s consolidated statements of operations and comprehensive loss as follows (in thousands): YEAR ENDED DECEMBER 31, 2018 2019 Research and development $ 195 $ 105 General and administrative 16 33 Cost of services for related-party revenue 58 159 Total $ 269 $ 297 The Company’s computation of share-based compensation expense for the years ended December 31, 2018 and December 31, 2019 is based on the fair value of ordinary shares of $1.85 and $1.91, respectively, and is adjusted for actual forfeitures as they occur. The fair value of each option grant during the years ended December 31, 2018 and December 31, 2019 was estimated on the date of grant using the Black-Scholes option-pricing model with the following: YEAR ENDED DECEMBER 31, 2018 2019 Expected term (in years) 5.2 – 6.0 4.4 – 6.0 Risk-free interest rate 2.6% – 3.0% 1.7% – 2.1% Expected dividend rate – – Expected share price volatility 66.5% – 68.7% 75.2% – 80.5% Expected Term. Risk-Free Interest Rate. Dividend Yield. Volatility. Estimated Fair Value (b) Founder Stock Activity The following table provides a summary of Founder Stock activity: NUMBER OF WEIGHTED-AVERAGE Unvested at December 31, 2017 455,477 $0.35 Vested (341,613 ) 0.35 Unvested at December 31, 2018 113,864 0.35 Vested (113,864 ) 0.35 Unvested at December 31, 2019 — $ — There were no Founder Stock granted during the years ended December 31, 2018 and December 31, 2019. The total fair value of Founder Stock that vested during the years ended December 31, 2018 and December 31, 2019 were $0.1 million and $40,000, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Predecessor Company
Income Taxes	(7) INCOME TAXES The domestic (Ireland) and foreign components of pre-tax DECEMBER 31, 2018 2019 Foreign $ (12,576 ) $ (16,803 ) Domestic (Ireland) (1,110 ) (2,406 ) Loss before income taxes $ (13,686 ) $ (19,209 ) The provision for income taxes consist of the following (in thousands): YEAR ENDED 2018 2019 Current Domestic (Ireland) $ — $ — State (U.S.) 1 1 Foreign/federal 44 33 Total current 45 34 Deferred Domestic (Ireland) $ — $ — State (U.S.) — — Foreign/federal — — Total deferred — — Provision for income taxes $ 45 $ 34 A reconciliation of the Irish statutory income tax rate of 12.5% to the actual tax rate for the years ended December 31, 2018 and December 31, 2019 are as follows (in thousands): YEAR ENDED 2018 2019 At statutory rate $ (1,711 ) $ (2,401 ) Foreign income tax at different rates 1,404 378 U.S. R&D credits (499 ) (861 ) Change in valuation allowance 732 3,733 Share-based compensation 57 60 Prior period true ups (38 ) (950 ) Other 100 75 Provision for income taxes $ 45 $ 34 Significant components of the Company’s deferred tax assets as of December 31, 2018 and December 31, 2019 are as follows (in thousands): DECEMBER 31, 2018 2019 Deferred tax assets: Net operating loss carryforwards $ 363 $ 3,259 Research & other credits 1,701 3,260 Other 208 333 Total gross DTA $ 2,272 $ 6,852 Less: Val. Allowance (2,181 ) (6,686 ) Total deferred tax assets $ 91 $ 166 Deferred tax liabilities: Fixed assets $ (91 ) $ 166 Total gross DTL $ (91 ) $ 166 Net deferred tax assets $ — $ — Realization of deferred tax assets is dependent upon the Company generating future taxable income, the timing and amount of which are uncertain. Accordingly, the deferred tax assets have been largely offset by a valuation allowance. The valuation allowance increased by approximately $0.8 million and $4.5 million for the years ended December 31, 2018 and December 31, 2019, respectively. As of December 31, 2019, the Company had a net operating loss carryforwards for U.S. state income tax purposes of approximately $30.9 million, that expire in the year 2038, and for Ireland income tax purposes of approximately $4.0 million that never expire. As of December 31, 2019, the Company had U.S. federal research and development credit carryforwards of approximately $1.5 million, that expire in the year 2038, and U.S. state research and development credit carryforwards of approximately $2.4 million, that do not expire. Utilization of the Company’s U.S. net operating loss and credit carryforwards may be subject to substantial annual limitation due to the ownership change limitations provided by the Internal Revenue Code and similar state provisions. Such annual limitation could result in the expiration of the U.S. net operating loss and credit carryforwards before utilization. To date, the Company has not performed an analysis to determine whether there would be a substantial annual limitation due to a change in ownership. Unrecognized Tax Benefits The Company’s policy is to include interest and penalties related to unrecognized tax benefits, if any, within the provision for taxes in the consolidated statements of operations and comprehensive loss. If the Company is eventually able to recognize its uncertain tax positions, the Company’s effective tax rate would be reduced. The Company currently has a full valuation allowance against its net deferred tax asset which would impact the timing of the effective tax rate benefit should any of these uncertain tax positions be favorably settled in the future. The Company files income tax returns in Ireland, the U.S., and Malta. All of the Company’s tax years since 2015 remain open to examination. The Company has the following activity relating to unrecognized tax benefits (in thousands): DECEMBER 31, 2018 2019 Beginning balance $ 247 $ 418 Gross increase—tax positions in prior periods 11 9 Gross decreases—tax positions in prior periods — (7 ) Gross increases—tax positions in prior periods 160 272 Ending balance $ 418 $ 692 Although it is reasonably possible that certain unrecognized tax benefits may increase or decrease within the next 12 months due to tax examination changes, settlement activities, expirations of statute of limitations or the impact on recognition and measurement considerations related to the results of published tax cases or other similar activities, the Company does not anticipate any significant changes to unrecognized tax benefits over the next 12 months. During the years ended December 31, 2018 and December 31, 2019, no interest or penalties were required to be recognized relating to unrecognized tax benefits.

Commitments & Contingencies

Commitments & Contingencies	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Commitments & Contingencies	(11) COMMITMENTS AND CONTINGENCIES Guarantees and Indemnifications In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnifications. The Company’s exposure under these agreements is unknown because it involves claims that may be made against the Company in the future but have not yet been made. To date, the Company has not paid any claims or been required to defend any action related to its indemnification obligations. However, the Company may record charges in the future as a result of these indemnification obligations. The Company also has indemnification obligations to its officers and directors for specified events or occurrences, subject to some limits, while they are serving at the Company’s request in such capacities. There have been no claims to date and the Company has director and officer insurance that may enable the Company to recover a portion of any amounts paid for future potential claims. The Company believes the fair value of these indemnification agreements is minimal. Accordingly, the Company has not recorded any liabilities for these agreements as of September 30, 2020. Contingencies From time to time, the Company may be a party to various claims in the normal course of business. Legal fees and other costs associated with such actions will be expensed as incurred. The Company will assess, in conjunction with its legal counsel, the need to record a liability for litigation and contingencies. Reserve estimates will be recorded when and if it is determined that a loss related matter is both probable and reasonably estimable. For the nine months ended September 30, 2020 the Company had no pending or threatened litigation. Contractual Obligations and Other Commitments The Company has contractual obligations from its operating lease, manufacturing and service contracts, Term Loan, and other research and development activities. The following table aggregates the Company’s material expected contractual obligations and commitments as of September 30, 2020 (in thousands): SEPTEMBER 30, 2020 TOTAL 2020 (4) 2021 - 2022 2023 - 2024 THEREAFTER Operating lease obligations (1) $ 380 $ 34 $ 284 $ 62 $ — Manufacturing and service contracts (2) 7,622 6,238 1,384 — — Term loan (3) 6,856 106 6,750 — — Total $ 14,858 $ 6,378 $ 8,418 $ 62 $ — (1) Payments due for the office space in Burlingame, California under a single operating sub-lease (2) In November 2015, the Company entered into a Master Service Agreement, or the MSA, with KBI Biopharma, Inc. relating to formulation development, process development and cGMP manufacturing of ALX148 for use in clinical trials on a project basis. The MSA had an initial term of three years with successive one-year non-exclusive. non-cancellable (3) On December 20, 2019, the Company borrowed a loan pursuant to the Loan Agreement. See Note 5 to these condensed consolidated financial statements for additional details. (4) Remaining three months. The Company enters into contracts in the normal course of business with various third parties for clinical trials, preclinical research studies and testing, manufacturing and other services and products for operating purposes. These contracts generally provide for termination upon notice. Payments due upon cancellation consist only of payments for services provided or expenses incurred, including non-cancellable Facilities In 2017, the Company entered into a lease agreement for office space for a period of five years and four months, commencing February 1, 2018 and ending May 31, 2023. In July 2020, the Company (i) assigned to Tallac Therapeutics (Note 9) the Company’s lease with respect to the premises located at 866 Malcolm Road, Burlingame, California, and (ii) received a sub-lease Minimum rent payments under operating leases are recognized on a straight-line basis over the term of the lease including any periods of free rent. Rent expense was $0.2 million and $0.1 million for the three months ended September 30, 2019 and 2020, respectively, and $0.6 million and $0.5 million for the nine months ended September 30, 2019 and 2020, respectively. Sub-lease
Predecessor Company
Commitments & Contingencies		(8) COMMITMENTS & CONTINGENCIES In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnifications. The Company’s exposure under these agreements is unknown because it involves claims that may be made against the Company in the future but have not yet been made. To date, the Company has not paid any claims or been required to defend any action related to its indemnification obligations. However, the Company may record charges in the future as a result of these indemnification obligations. The Company also has indemnification obligations to its officers and directors for specified events or occurrences, subject to some limits, while they are serving at the Company’s request in such capacities. There have been no claims to date and the Company has director and officer insurance that may enable the Company to recover a portion of any amounts paid for future potential claims. The Company believes the fair value of these indemnification agreements is minimal. Accordingly, the Company has not recorded any liabilities for these agreements as of December 31, 2018 and December 31, 2019. Legal Proceedings From time to time, the Company may be a party to various claims in the normal course of business. Legal fees and other costs associated with such actions will be expensed as incurred. The Company will assess, in conjunction with its legal counsel, the need to record a liability for litigation and contingencies. Reserve estimates will be recorded when and if it is determined that a loss related matter is both probable and reasonably estimable. For the years ended December 31, 2018 and December 31, 2019, the Company had no pending or threatened litigation. Contractual Obligations and Other Commitments The following table summarizes the Company’s commitments and contractual obligations as of December 31, 2019 (in thousands): YEAR ENDED DECEMBER 31: OPERATING MANUFACTURING (2) TERM LOAN 2020 $ 544 $ 926 $ 401 2021 560 5,805 3,743 2022 577 — 3,007 2023 247 — — Total $ 1,928 $ 6,731 $ 7,151 (1) Payments due for the office and laboratory space in Burlingame, California under a single operating lease agreement that expires in 2023. (2) These amounts are based on non-cancellable (3) In December 2019, the Company entered into a term loan pursuant to the Loan Agreement as described above in Note 4. Facilities In 2015, the Company entered into a noncancelable lease for office space for a period of three years and two months, commencing March 2015 and ending May 31, 2018. In 2016, the Company entered into a sublease agreement for office space for a period of four years, commencing June 2016 and ending May 31, 2020. This sublease was terminated early in May 2018 without any fees and penalties. In 2017, the Company entered into a lease agreement for office space for a period of five years and four months, commencing February 1, 2018 and ending May 31, 2023. Minimum rent payments under operating leases are recognized on a straight-line basis over the term of the lease including any periods of free rent. Rent expense for years ended December 31, 2018 and December 31, 2019 were $1.0 million and $0.8 million, respectively. Manufacturing and Service Contracts In November 2015, the Company entered into a Master Service Agreement, or MSA, with KBI Biopharma, Inc, or KBI, relating to formulation development, process development and cGMP manufacturing of ALX148 for use in clinical trials on a project basis. The MSA had an initial term of three years which the Company subsequently extended. See table above for future committed purchases with KBI. The Company also enters into other contracts in the normal course of business with CROs, contract development and manufacturing organizations and other service providers and vendors. These contracts generally provide for termination on short notice and are cancelable contracts and, accordingly, are not included in the contractual obligations and disclosures summarized above.

License Agreement

License Agreement	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
License Agreement	(8) LICENSE AGREEMENT Exclusive (Equity) Agreement with The Board of Trustees of the Leland Stanford Junior University In March 2015, the Company entered into a license agreement, or the Stanford Agreement, with the Board of Trustees of the Leland Stanford Junior University, or Stanford, under which the Company obtained a worldwide, royalty-bearing, sublicensable license under certain patents relating to the Company’s current product candidates, to develop, manufacture and commercialize products for use in certain licensed fields, the scope of which would include the application of the licensed intellectual property in oncology. The license granted to the Company in the Stanford Agreement includes an exclusive grant, subject to certain pre-existing non-exclusive non-exclusive In consideration for the rights granted to the Company under the Stanford Agreement, the Company paid Stanford a nonrefundable license royalty and reimbursed Stanford for past patent expenses, together totaling less than $0.1 million, and granted Stanford a specified number of shares of common stock of the Company. In addition, the Company is obligated to pay Stanford ongoing patent expenses and an annual license maintenance fee, which are nominal and will be creditable against any royalties payable to Stanford in the applicable year. The Company is required to make milestone payments up to an aggregate of $5.0 million in respect of a specified number of licensed products that successfully satisfy certain clinical and regulatory milestones. No milestone payments have been made through September 30, 2020. The Company also agreed to pay Stanford tiered royalties on a specified percentage of net sales made by the Company, its affiliates and its sublicensees of licensed products at rates ranging within low single-digit percentages, subject to certain reductions and offsets. The license, on a licensed product-by-licensed country-by-country paid-up non-exclusively The Company may terminate the Stanford Agreement, on a licensed product-by-licensed product-by-licensed Commercial License Agreement with Selexis SA In June 2016, the Company entered into a license agreement with Selexis SA, or Selexis, under which the Company obtained a worldwide, royalty-bearing, sublicensable license under certain patents, know-how In consideration for the rights granted to the Company under the agreement, the Company paid Selexis a nominal one-time product-by-product country-by-country paid-up The Company may terminate the license agreement at any time for any reason with at least 60 days’ written notice to Selexis. Either party may terminate the license agreement if the other party enters into a bankruptcy event or in the event of a material breach of the agreement (that cannot be cured or remains uncured for 60 days after the date that the defaulting party is provided with written notice of such breach). The Company’s obligations to pay royalties that are accrued or accruable will survive any termination of the agreement, and in certain circumstances the licenses granted under the agreement will terminate unless they have become fully paid up as described in the previous paragraph. Commercial Antibody Agreement with Crystal Bioscience Inc. (Now a Subsidiary of Ligand Pharmaceuticals Incorporated) In March 2017, the Company entered into an agreement with Crystal Bioscience Inc. (now a subsidiary of Ligand Pharmaceuticals Incorporated), or Crystal, under which the Company obtained an assignment of certain patents, covering certain SIRP a non-exclusive know-how In consideration for the rights granted to the Company under the agreement, it agreed to pay Crystal milestone payments up to $11.1 million in respect of all licensed products developed under the assigned patents, that successfully satisfy certain clinical and regulatory milestones, each milestone being paid only once for all products. The Company also agreed to pay Crystal tiered royalties on net sales made by the Company, its affiliates and sublicensees of products at rates ranging within low single-digit percentages, subject to certain potential reductions. This royalty obligation, on a product-by-product country-by-country paid-up The Company agreed to use commercially reasonable efforts to develop and commercialize licensed products, including meeting defined development milestones by certain specified dates. The Company may terminate the agreement at any time for any reason with at least 60 days’ written notice to Crystal. Either party may terminate the agreement if the other party enters into a bankruptcy event or in the event of material breach of the agreement (that remains uncured for 60 days after the date that it is provided with written notice of such breach). The Company’s obligations to pay royalties and milestone payments which accrued pre-termination
Predecessor Company
License Agreement		(9) LICENSE AGREEMENT Exclusive (Equity) Agreement with The Board of Trustees of the Leland Stanford Junior University In March 2015, the Company entered into a license agreement, or the Stanford Agreement, with the Board of Trustees of the Leland Stanford Junior University, or Stanford, under which the Company obtained a worldwide, royalty-bearing, sublicensable license under certain patents relating to the Company’s current product candidates, to develop, manufacture and commercialize products for use in certain licensed fields, the scope of which would include the application of the licensed intellectual property in oncology. The license granted to the Company in the Stanford Agreement includes an exclusive grant, subject to certain pre-existing non-exclusive non-exclusive In consideration for the rights granted to the Company under the Stanford Agreement, the Company paid Stanford a nonrefundable license royalty and reimbursed Stanford for past patent expenses, together totaling less than $0.1 million, and granted Stanford a specified number of ordinary shares of the Company. In addition, the Company is obligated to pay Stanford ongoing patent expenses and an annual license maintenance fee, which are nominal and will be creditable against any royalties payable to Stanford in the applicable year. The Company is required to make milestone payments up to an aggregate of $5.0 million in respect of a specified number of licensed products that successfully satisfy certain clinical and regulatory milestones. No milestone payments have been made through December 31, 2019. The Company also agreed to pay Stanford tiered royalties on a specified percentage of net sales made by the Company, its affiliates and its sublicensees of licensed products at rates ranging within low single-digit percentages, subject to certain reductions and offsets. The license, on a licensed product-by-licensed country-by-country paid-up non-exclusively The Company may terminate the Stanford Agreement, on a licensed product-by-licensed product-by-licensed Commercial License Agreement with Selexis SA In June 2016, the Company entered into a license agreement with Selexis SA, or Selexis, under which the Company obtained a worldwide, royalty-bearing, sublicensable license under certain patents, know-how In consideration for the rights granted to the Company under the agreement, the Company paid Selexis a nominal one-time product-by-product country-by-country paid-up The Company may terminate the license agreement at any time for any reason with at least 60 days’ written notice to Selexis. Either party may terminate the license agreement if the other party enters into a bankruptcy event or in the event of a material breach of the agreement (that cannot be cured or remains uncured for 60 days after the date that the defaulting party is provided with written notice of such breach). The Company’s obligations to pay royalties that are accrued or accruable will survive any termination of the agreement, and in certain circumstances the licenses granted under the agreement will terminate unless they have become fully paid up as described in the previous paragraph. Commercial Antibody Agreement with Crystal Bioscience, Inc. (Now a Subsidiary of Ligand Pharmaceuticals Incorporated) In March 2017, the Company entered into an agreement with Crystal Bioscience, Inc. (now a subsidiary of Ligand Pharmaceuticals Incorporated), or Crystal, under which the Company obtained an assignment of certain patents, covering certain SIRP a non-exclusive know-how In consideration for the rights granted to the Company under the agreement, it agreed to pay Crystal milestone payments up to $11.1 million in respect of all licensed products developed under the assigned patents, that successfully satisfy certain clinical and regulatory milestones, each milestone being paid only once for all products. The Company also agreed to pay Crystal tiered royalties on net sales made by the Company, its affiliates and sublicensees of products at rates ranging within low single-digit percentages, subject to certain potential reductions. This royalty obligation, on a product-by-product country-by-country paid-up The Company agreed to use commercially reasonable efforts to develop and commercialize licensed products, including meeting defined development milestones by certain specified dates. The Company may terminate the agreement at any time for any reason with at least 60 days’ written notice to Crystal. Either party may terminate the agreement if the other party enters into a bankruptcy event or in the event of material breach of the agreement (that remains uncured for 60 days after the date that it is provided with written notice of such breach). The Company’s obligations to pay royalties and milestone payments which accrued pre-termination

Defined Contribution Plan

Defined Contribution Plan	12 Months Ended
	Dec. 31, 2019
Predecessor Company
Defined Contribution Plan	(10) DEFINED CONTRIBUTION PLAN The Company has a qualified 401(k) Savings and Investment Plan, or the Plan, whereby employees may contribute up to the Federal annual limits. The Company does not match employee contributions.

Related-Party Transactions

Related-Party Transactions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Related-Party Transactions	(9) RELATED-PARTY TRANSACTIONS Related-party revenue In June 2018, the Company entered into a Research and Development Services Agreement, or Tollnine Agreement, with Tollnine, a related-party of the Company, to provide research and development services to Tollnine. The Company’s Chief Executive Officer was also the Chief Executive Officer of Tollnine until April 2020 and two of the Company’s investors are also investors in Tollnine. As such, Tollnine was deemed to be a related-party. The Tollnine Agreement has an initial term of 3 years, to be automatically renewed for additional one-year mark-up Receivables due from related-party As of December 31, 2019 and September 30, 2020, the Company had outstanding related-party receivables from Tollnine of $0.5 million. Tallac Service Agreement The Company entered into a research and development services agreement, or the Tallac Services Agreement, with Tallac Therapeutics effective as of July 1, 2020. The Tallac Services Agreement provides that Tallac Therapeutics will provide certain preclinical research services to the Company for a service fee based on the costs incurred by Tallac Therapeutics plus a mark-up
Predecessor Company
Related-Party Transactions		(11) RELATED-PARTY TRANSACTIONS Related-Party Revenue In June 2018, the Company entered into a Research and Development Services Agreement, or Tollnine Agreement, with Tollnine, Inc., or Tollnine, a related-party of the Company, to provide research and development services to Tollnine. The Company’s Chief Executive Officer is also the Chief Executive Officer of Tollnine and two of the Company’s investors are also investors in Tollnine. As such, Tollnine was deemed to be a related-party. The Tollnine Agreement has an initial term of 3 years, to be automatically renewed for additional one-year mark-up Receivables due from Related-Party As of December 31, 2018, and 2019, the Company had outstanding related-party receivables from Tollnine of $0.9 million and $0.5 million, respectively.

Net Loss Per Share Attributable

Net Loss Per Share Attributable To Common Stockholders	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Net Loss Per Share Attributable To Common Stockholders	(10) NET LOSS PER SHARE ATTRIBUTABLE TO COMMON STOCKHOLDERS The following table sets forth the computation of the basic and diluted net loss per share attributable to common stockholders (in thousands, except share and per share data): THREE MONTHS ENDED NINE MONTHS ENDED 2019 2020 2019 2020 Numerator: Net loss $ (3,044 ) $ (10,181 ) $ (11,479 ) $ (26,966 ) Less: cumulative preferred dividends allocated to preferred stockholders (1,071 ) (578 ) (2,957 ) (5,202 ) Net loss attributable to common stockholders $ (4,115 ) $ (10,759 ) $ (14,436 ) $ (32,168 ) Denominator: Weighted-average shares of common stock outstanding 3,100,544 29,664,122 3,061,082 12,052,876 Net loss per share attributable to common stockholders, basic and diluted $ (1.33 ) $ (0.36 ) $ (4.72 ) $ (2.67 ) Since the Company was in a loss position for all periods presented, basic net loss per share is the same as diluted net loss per share for all periods presented as the inclusion of all potential common stock outstanding would have been anti-dilutive. The following outstanding potentially dilutive securities were excluded from the computation of diluted net loss per share for the three and nine months ended September 30, 2019 and 2020, because including them would have been anti-dilutive: SEPTEMBER 30, 2019 2020 Convertible preferred stock 10,313,808 — Common stock subject to repurchase 53,070 253 Options issued and outstanding 1,206,690 4,751,589 Total 11,573,568 4,751,842
Predecessor Company
Net Loss Per Share Attributable To Common Stockholders		(12) NET LOSS PER SHARE ATTRIBUTABLE TO ORDINARY SHAREHOLDERS AND UNAUDITED PRO FORMA NET LOSS PER SHARE The following table sets forth the computation of the basic and diluted net loss per share attributable to ordinary shareholders (in thousands, except share and per share data): YEAR ENDED DECEMBER 31, 2018 2019 Numerator: Net loss $ (13,731 ) $ (19,243 ) Less: cumulative dividends allocated to preferred shareholders (3,671 ) (4,028 ) Net loss attributable to ordinary shareholders $ (17,402 ) $ (23,271 ) Denominator: Weighted-average ordinary shares outstanding 2,750,838 3,076,461 Net loss per share attributable to ordinary shareholders, basic and diluted $ (6.33 ) $ (7.56 ) Since the Company was in a loss position for all periods presented, basic net loss per share is the same as diluted net loss per share for all periods as the inclusion of all potential ordinary shares outstanding would have been anti-dilutive. Potentially dilutive securities that were not included in the diluted per share calculations as of December 31, 2018 and December 31, 2019 because they would be anti-dilutive were as follows: DECEMBER 31, 2018 2019 Series A convertible preferred shares 9,297,081 9,297,081 Series B convertible preferred shares — 1,016,727 Warrants to purchase convertible preferred shares — 61,292 Ordinary shares subject to repurchase 229,912 34,024 Options issued and outstanding 864,819 1,183,745 Total 10,391,812 11,592,869 The following table sets forth the computation of the Company’s unaudited pro forma basic and diluted net loss per share (in thousands, except share and per share amounts): YEAR ENDED Net loss $ (19,243 ) Weighted-average ordinary shares used in computing net loss per share attributable to ordinary shareholders, basic and diluted 3,076,461 Pro forma adjustment to reflect assumed conversion of preferred shares and accrued dividends allocable to ordinary shareholders 11,253,839 Weighted-average ordinary shares used to compute pro forma net loss per share, basic and diluted 14,330,300 Pro forma net loss per share, basic and diluted $ (1.34 )

Organization and summary of s_2

Organization and summary of significant accounting policies (Policies)	Apr. 01, 2020	Sep. 30, 2020	Dec. 31, 2019
Basis of Presentation	Basis of Preparation The balance sheet is presented in accordance with accounting principles generally accepted in the United States of America, or U.S. GAAP. The statements of operations and comprehensive loss, stockholders’ equity, and cash flows have not been presented because there have been no activities at inception of this entity.	Basis of Preparation These condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or U.S. GAAP, and the applicable rules and regulations of the U.S. Securities and Exchange Commission, or SEC, for interim reporting.
Underwriting Commissions and Offering Costs	Underwriting Commissions and Offering Costs Underwriting commissions and offering costs to be incurred in connection with the Company’s common stock offerings will be reflected as a reduction in additional paid-in
Organizational Costs	Organizational Costs Organizational costs for costs incurred to organize the Company will be expensed as incurred.
Principles of Consolidation		Principles of Consolidation All intercompany balances and transactions have been eliminated in consolidation.
Unaudited Condensed Consolidated Financial Statements		Unaudited Condensed Consolidated Financial Statements The condensed consolidated balance sheet as of September 30, 2020, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2019 and 2020, the condensed consolidated statements of convertible preferred stock and stockholders’ equity (deficit) for the three and nine months ended September 30, 2019 and 2020, and the condensed consolidated statements of cash flows for the nine months ended September 30, 2019 and 2020, are unaudited. These unaudited condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s financial position as of September 30, 2020, and its results of operations for the periods presented. The results of operations for the three and nine months ended September 30, 2020, are not necessarily indicative of the results to be expected for any subsequent periods, including the year ended December 31, 2020, and therefore should not be relied upon as an indicator of future results. The condensed consolidated balance sheet as of December 31, 2019 included herein was derived from the audited consolidated financial statements as of that date. The accompanying condensed consolidated financial statements and related notes should be read in conjunction with the audited consolidated financial statements for the year ended December 31, 2019 and the notes thereto, which are included in the Company’s final prospectus for the Company’s initial public offering filed pursuant to Rule 424(b)(4) under the Securities Act of 1933, as amended, with the SEC on July 17, 2020.
Use of Estimates		Use of Estimates The preparation of the condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. On an ongoing basis, management evaluates its estimates, including those related to the estimated useful lives of long-lived assets, clinical trial accruals, fair value of assets and liabilities, Series B convertible preferred stock warrant liability, term loan compound derivative liability, term loan, valuation of the Company’s common stock, income taxes and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Cash and Cash Equivalents		Cash and Cash Equivalents The Company holds its cash and cash equivalents in checking and money market accounts. The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. Cash equivalents consist primarily of amounts invested in money market accounts and are stated at fair value.
Concentration of Credit Risk and Other Risks and Uncertainties		Concentration of Credit Risk and Other Risks and Uncertainties Financial instruments that potentially subject the Company to a 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, and invests in money market funds. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash and cash equivalents. The Company has not experienced any losses on its deposits of cash and cash equivalents. The Company’s future results of operations involve a number of other risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, uncertainty of results of clinical trials and reaching milestones, uncertainty of regulatory approval of the Company’s potential product candidates, uncertainty of market acceptance of the Company’s product candidates, competition from substitute products and larger companies, securing and protecting proprietary technology, strategic relationships and dependence on key individuals or sole-source suppliers. The Company’s product candidates require approvals from the U.S. Food and Drug Administration, or FDA, and comparable foreign regulatory agencies prior to commercial sales in their respective jurisdictions. There can be no assurance that any product candidates will receive the necessary approvals. If the Company was denied approval, approval was delayed or the Company was unable to maintain approval for any product candidate, it could have a materially adverse impact on the Company.
Property and Equipment		Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation of property and equipment is provided using the straight-line method over the estimated useful lives of the assets. Upon sale or retirement of assets, the cost and related accumulated depreciation or amortization are removed from the condensed consolidated balance sheet and the resulting gain or loss is reflected in the condensed consolidated statement of operations and comprehensive loss. Maintenance and repairs are charged to the condensed consolidated statement of operations and comprehensive loss as incurred.
Impairment of Long-Lived Assets		Impairment of Long-Lived Assets The Company reviews property and equipment for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amount to the future undiscounted net cash flows which the asset or asset group are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured as the amount by which the carrying amount of the assets exceeds its fair value. Fair value is determined using various valuation techniques including discounted cash flow models, quoted market values and third-party independent appraisals, as considered necessary. There were no impairment charges recognized in the three and nine months ended September 30, 2019 and 2020.
Fair Value of Financial Instruments		Fair Value of Financial Instruments The Company applies fair value accounting for all financial assets and liabilities and nonfinancial assets and liabilities that are required to be recognized or disclosed at fair value in the condensed consolidated financial statements. The Company defines fair value as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Where observable prices or inputs are not available valuation models are applied. These valuation techniques involve some level of management estimation and judgment, the degree of which is dependent on the price transparency for the instruments or market and the instruments’ complexity. The Company’s financial instruments consist of cash and cash equivalents, receivables due from related-party, accounts payable, the term loan compound derivative liability and the Series B convertible preferred stock warrant liability. The term loan compound derivative liability and the Series B convertible preferred stock warrant liability are re-measured
Term Loan		Term Loan The Company accounts for the Loan and Security Agreement, dated as of December 20, 2019, as amended, with Silicon Valley Bank, or SVB, and WestRiver Innovation Lending Fund VIII, LP, or WestRiver, collectively as lenders, and SVB, as administrative agent and collateral agent, as a liability measured at net proceeds less debt discount and is accreted to the face value of the term loan over its expected term using the effective interest method. The Company considers whether there are any embedded features in its debt instruments that require bifurcation and separate accounting as derivative financial instruments pursuant to Accounting Standards Codification, or ASC, Topic 815, Derivatives and Hedging
Convertible Preferred Stock		Convertible Preferred Stock The Company records convertible preferred stock net of issuance costs on the dates of issuance, which represents the carrying value. In the event of a change of control of the Company, proceeds will be distributed in accordance with the liquidation preferences set forth in its organization documents unless the holders of convertible preferred stock have converted their convertible preferred stock into common stock. Convertible preferred stock are classified outside of stockholders’ equity (deficit) on the accompanying condensed consolidated balance sheets as events triggering the liquidation preferences are not solely within the Company’s control. The Company has elected not to adjust the carrying values of the convertible preferred stock to the liquidation preferences of such shares because of the uncertainty of whether or when such an event would occur. Upon the consummation of the Company’s initial public offering in July 2020, all shares of convertible preferred stock outstanding and accrued cumulative dividends automatically converted into 23,934,533 shares of common stock.
Revenue Recognition		Revenue Recognition To date, the Company has derived revenue from providing research and development services on a time and materials basis to a related-party. The Company recognizes such revenues over time as services are delivered, and invoices the customer as the work is incurred in arrears. The Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Company determines are within the scope of Topic 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies a performance obligation. As part of the Company’s consideration as to whether the Company has entered into a contract with a customer, it considers whether it is probable that it will collect the consideration it is entitled to in exchange for the goods and services it transfers to the customer. At contract inception, the Company assesses the goods or services promised within each contract that falls under the scope of Topic 606, determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied.
Cost of Services for Related-Party Revenue		Cost of Services for Related-Party Revenue The Company incurs costs associated with related-party services including direct labor and associated employee benefits, laboratory supplies, and other expenses. These costs are recorded in cost of services for related-party revenue as a component of total operating expenses in the accompanying condensed consolidated statements of operations and comprehensive loss.
Research and Development Costs		Research and Development Costs Research and development costs are expensed as incurred and consist primarily of salaries and benefits, stock-based compensation expense, lab supplies and facility costs, as well as fees paid to nonemployees and entities that conduct certain research and development activities on behalf of the Company and expenses incurred in connection with license agreements (Note 8). Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are capitalized and recorded in prepaid expenses and other current assets, and then expensed as the related goods are delivered or the services are performed.
Clinical and Manufacturing Accruals		Clinical and Manufacturing Accruals The Company records accruals for estimated costs of research, preclinical studies and clinical trials, and manufacturing development, which are a significant component of research and development expenses. A substantial portion of the Company’s ongoing research and development activities are conducted by third-party service providers, including contract research organizations, or CROs, and contract manufacturing organizations, or CMOs. The Company’s contracts with CROs generally include pass-through fees such as regulatory expenses, investigator fees, travel costs and other miscellaneous costs, including shipping and printing fees. The financial terms of these contracts are subject to negotiations, which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company accrues the costs incurred under agreements with these third parties based on estimates of actual work completed in accordance with the respective agreements. The Company determines the estimated costs through discussions with internal personnel and external service providers as to the progress or stage of completion of the services and the agreed-upon fees to be paid for such services. The Company makes significant judgments and estimates in determining the accrual balance at the end of each reporting period. As actual costs become known, the Company adjusts its accruals. Although the Company does not expect its estimates to be materially different from amounts actually incurred, the Company’s understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and could result in the Company reporting amounts that are too high or too low in any particular period. To assist in its estimates the Company relies upon the receipt of timely and accurate reporting from its clinical and non-clinical
Share-Based Compensation Expense		Stock-based Compensation Expense The Company accounts for stock-based compensation by measuring and recognizing compensation expense for all stock-based payments made to employees, directors and non-employees
Segment Reporting		Segment Reporting The Company manages its operations as a single operating segment for the purposes of assessing performance and making operating decisions.
Foreign Currency Transactions		Foreign Currency Transactions The functional currency of the Company’s operation and each of its subsidiaries is U.S. dollars. All assets and liabilities denominated in a foreign currency are translated into U.S. dollars at the exchange rate prevailing on the balance sheet date. Expenses are translated at the average exchange rates prevailing during the applicable period. Foreign currency transaction gains and losses are included in the consolidated statement of operations and comprehensive loss and recorded in other expense, net, and were immaterial for the three and nine months ended September 30, 2019 and 2020, respectively.
Income Taxes		Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the condensed consolidated financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the condensed consolidated financial statement carrying amounts and tax bases of assets and liabilities using enacted tax rates in effect for the period in which the temporary differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in the condensed consolidated statements of operations and comprehensive loss in the period that includes the enactment date. The Company recognizes deferred tax assets to the extent that it believes these assets are more likely than not to be realized. In making such a determination, the Company considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning
Net Loss Per Share Attributable to Common Stockholders		Net Loss Per Share Attributable to Common Stockholders Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive given the net loss for each period presented. The Company applies the two-class two-class two-class two-class
Recent Accounting Pronouncements		Recent Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02 Leases 2016-02). 2016-02 No. 2016-02 No. 2020-05, No. 2016-02 non-public In December 2019, the FASB issued ASU No. 2019-12, 2019-12
New Accounting Pronouncements Recently Adopted		New Accounting Pronouncements Recently Adopted In June 2016, the FASB issued ASU No. 2016-13, In September 2018, the FASB issued ASU No. 2018-13, 2018-13 2018-13
Reverse Stock Split		Reverse Stock Split On July 8, 2020, the Company’s board of directors approved an amendment to the Company’s certificate of incorporation to effect a 1-for-6.5806
Deferred Offering Costs		Deferred Offering Costs The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process paid-in
Comprehensive Loss		Comprehensive Loss Comprehensive loss is equal to net loss for all periods presented.
Predecessor Company
Basis of Presentation			Basis of Preparation These consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or U.S. GAAP.
Principles of Consolidation			Principles of Consolidation All intercompany balances and transactions have been eliminated in consolidation.
Unaudited Condensed Consolidated Financial Statements			Unaudited Pro Forma Information Immediately prior to the completion of this offering, all outstanding convertible preferred shares will automatically convert into ordinary shares. Unaudited pro forma basic and diluted net loss per share has been computed to give effect to the conversion of all outstanding convertible preferred shares and cumulative dividends on the convertible preferred shares into ordinary shares. The unaudited pro forma net loss per share does not include the shares expected to be sold and related proceeds to be received from the initial public offering.
Need for Additional Capital			Need for Additional Capital Since commencing operations, none of the Company’s product candidates have received marketing approval from the U.S. Food and Drug Administration, or FDA, or any other federal, state, local or foreign governmental or regulatory authority and therefore the Company has not generated any revenue from drug product sales. The Company had an accumulated deficit of $72.8 million as of December 31, 2019 and management does not expect to experience positive cash flows in the foreseeable future. Based on management’s current plans, management believes cash of $9.0 million as of December 31, 2019, along with the $105.0 million of gross proceeds from the issuance of Series C convertible preferred shares in February 2020 (Note 13), are sufficient to fund operations through at least one year from the date of the issuance of these consolidated financial statements. Management expects to incur additional losses in the future to conduct product candidate research and development and to conduct pre-commercialization out-license
Use of Estimates			Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. On an ongoing basis, management evaluates its estimates, including those related to the estimated useful lives of long-lived assets, clinical trial accruals, fair value of assets and liabilities, Series B convertible preferred shares warrant liability, term loan compound derivative liability, term loan, valuation of ordinary shares, income taxes and share-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Cash and Cash Equivalents			Cash The Company holds its cash in checking and interest-bearing accounts.
Concentration of Credit Risk and Other Risks and Uncertainties			Concentration of Credit Risk and Other Risks and Uncertainties Financial instruments that potentially subject the Company to a concentration of credit risk consist primarily of cash. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash. The Company has not experienced any losses on its deposits of cash. The Company’s future results of operations involve a number of other risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, uncertainty of results of clinical trials and reaching milestones, uncertainty of regulatory approval of the Company’s potential product candidates, uncertainty of market acceptance of the Company’s product candidates, competition from substitute products and larger companies, securing and protecting proprietary technology, strategic relationships and dependence on key individuals or sole-source suppliers. The Company’s product candidates require approvals from the FDA and comparable foreign regulatory agencies prior to commercial sales in their respective jurisdictions. There can be no assurance that any product candidates will receive the necessary approvals. If the Company was denied approval, approval was delayed or the Company was unable to maintain approval for any product candidate, it could have a materially adverse impact on the Company.
Property and Equipment			Property and Equipment Property and equipment are stated at cost less accumulated depreciation. Depreciation of property and equipment is provided using the straight-line method over the estimated useful lives of the assets (Note 3). Upon sale or retirement of assets, the cost and related accumulated depreciation or amortization are removed from the consolidated balance sheet and the resulting gain or loss is reflected in the consolidated statement of operations and comprehensive loss. Maintenance and repairs are charged to the consolidated statement of operations and comprehensive loss as incurred. The useful lives of the property and equipment are as follows: Research and development equipment 5 years Furniture and office equipment 5 years Computer equipment 3 years Software 3 years Leasehold improvements Shorter of 7 years or remaining of lease term
Impairment of Long-Lived Assets			Impairment of Long-Lived Assets The Company reviews property and equipment for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amount to the future undiscounted net cash flows which the asset or asset group are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured as the amount by which the carrying amount of the assets exceeds its fair value. Fair value is determined using various valuation techniques including discounted cash flow models, quoted market values and third-party independent appraisals, as considered necessary. There were no impairment charges recognized in the years ended December 31, 2018 and December 31, 2019.
Fair Value of Financial Instruments			Fair Value of Financial Instruments The Company applies fair value accounting for all financial assets and liabilities and nonfinancial assets and liabilities that are required to be recognized or disclosed at fair value in the consolidated financial statements. The Company defines fair value as the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Where observable prices or inputs are not available valuation models are applied. These valuation techniques involve some level of management estimation and judgment, the degree of which is dependent on the price transparency for the instruments or market and the instruments’ complexity. The Company’s financial instruments consist of cash, accounts receivable, accounts payable, the term loan compound derivative liability and the Series B convertible preferred shares warrant liability. The term loan compound derivative liability and the Series B convertible preferred shares warrant liability are re-measured
Term Loan			Term Loan The Company accounts for the Loan and Security Agreement, dated as of December 20, 2019, with Silicon Valley Bank, and WestRiver Innovation Lending Fund VIII, LP, collectively as lenders, and Silicon Valley Bank, as administrative agent and collateral agent, as a liability measured at net proceeds less debt discount and is accreted to the face value of the term loan over its expected term using the effective interest method. The Company considers whether there are any embedded features in its debt instruments that require bifurcation and separate accounting as derivative financial instruments pursuant to Accounting Standards Codification, or ASC, Topic 815, Derivatives and Hedging
Convertible Preferred Stock			Convertible Preferred Shares The Company records convertible preferred shares net of issuance costs on the dates of issuance, which represents the carrying value. In the event of a change of control of the Company, proceeds will be distributed in accordance with the liquidation preferences set forth in its Constitution unless the holders of convertible preferred shares have converted their convertible preferred shares into ordinary shares. Convertible preferred shares are classified outside of shareholders’ deficit on the accompanying consolidated balance sheets as events triggering the liquidation preferences are not solely within the Company’s control. The Company has elected not to adjust the carrying values of the convertible preferred shares to the liquidation preferences of such shares because of the uncertainty of whether or when such an event would occur.
Revenue Recognition			Revenue Recognition To date, the Company has derived revenue from providing research and development services on a time and materials basis to a related-party. The Company recognizes such revenues over time as services are delivered, and invoices the customer as the work is incurred in arrears. Effective January 1, 2018, the Company adopted ASC Topic 606, Revenue from Contracts with Customers To determine revenue recognition for arrangements that the Company determines are within the scope of Topic 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies a performance obligation. As part of the Company’s consideration as to whether the Company has entered into a contract with a customer, it considers whether it is probable that it will collect the consideration it is entitled to in exchange for the goods and services it transfers to the customer. At contract inception, the Company assesses the goods or services promised within each contract that falls under the scope of Topic 606, determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated based on their standalone selling price to the respective performance obligation when (or as) the performance obligation is satisfied.
Cost of Services for Related-Party Revenue			Cost of Services for Related-Party Revenue The Company incurs costs associated with related-party services including direct labor and associated employee benefits, laboratory supplies, and other expenses. These costs are recorded in cost of services for related-party revenue as a component of total operating expenses in the accompanying consolidated statements of operations and comprehensive loss.
Research and Development Costs			Research and Development Costs Research and development costs are expensed as incurred and consist primarily of salaries and benefits, share-based compensation expense, lab supplies and facility costs, as well as fees paid to nonemployees and entities that conduct certain research and development activities on behalf of the Company and expenses incurred in connection with license agreements (Note 9). Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are capitalized and recorded in prepaid expenses and other current assets, and then expensed as the related goods are delivered or the services are performed.
Clinical and Manufacturing Accruals			Clinical and Manufacturing Accruals The Company records accruals for estimated costs of research, preclinical studies and clinical trials, and manufacturing development, which are a significant component of research and development expenses. A substantial portion of the Company’s ongoing research and development activities are conducted by third-party service providers, including contract research organizations, or CROs, and contract manufacturing organizations, or CMOs. The Company’s contracts with CROs generally include pass-through fees such as regulatory expenses, investigator fees, travel costs and other miscellaneous costs, including shipping and printing fees. The financial terms of these contracts are subject to negotiations, which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company accrues the costs incurred under agreements with these third parties based on estimates of actual work completed in accordance with the respective agreements. The Company determines the estimated costs through discussions with internal personnel and external service providers as to the progress or stage of completion of the services and the agreed-upon fees to be paid for such services. The Company makes significant judgments and estimates in determining the accrual balance at the end of each reporting period. As actual costs become known, the Company adjusts its accruals. Although the Company does not expect its estimates to be materially different from amounts actually incurred, the Company’s understanding of the status and timing of services performed relative to the actual status and timing of services performed may vary and could result in the Company reporting amounts that are too high or too low in any particular period. To assist in its estimates the Company relies upon the receipt of timely and accurate reporting from information provided as part of its clinical and non-clinical
Share-Based Compensation Expense			Share-Based Compensation Expense The Company accounts for share-based compensation by measuring and recognizing compensation expense for all share-based payments made to employees, directors and non-employees
Segment Reporting			Segment Reporting The Company manages its operations as a single operating segment for the purposes of assessing performance and making operating decisions. All of the Company’s assets are maintained in the United States and Ireland.
Foreign Currency Transactions			Foreign Currency Transactions The functional currency of the Company’s operation and each of its subsidiaries is U.S. dollars. All assets and liabilities denominated in a foreign currency are translated into U.S. dollars at the exchange rate prevailing on the balance sheet date. Expenses are translated at the average exchange rates prevailing during the applicable period. Foreign currency transaction gains and losses are included in the consolidated statement of operations and comprehensive loss and recorded in other income (expense), net, and was immaterial for the years ended December 31, 2018 and December 31, 2019, respectively.
Income Taxes			Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the consolidated financial statement carrying amounts and tax bases of assets and liabilities using enacted tax rates in effect for the period in which the temporary differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in the consolidated statements of operations and comprehensive loss in the period that includes the enactment date. The Company recognizes deferred tax assets to the extent that it believes these assets are more likely than not to be realized. In making such a determination, the Company considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning The Company recognizes benefits of uncertain tax positions if it is more likely than not that such positions will be sustained upon examination based solely on their technical merits, as the largest amount of benefit that is more likely than not to be realized upon the ultimate settlement. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit.
Net Loss Per Share Attributable to Common Stockholders			Net Loss Per Share Attributable to Ordinary Shareholders Basic net loss per share is calculated by dividing the net loss attributable to ordinary shareholders by the weighted-average number of ordinary shares outstanding during the period, without consideration for ordinary share equivalents. Net loss attributable to ordinary shareholders is calculated by adjusting net loss of the Company for cumulative preferred share dividends. Diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive given the net loss for each period presented. The Company applies the two-class two-class two-class two-class Unaudited Pro Forma Net Loss Per Share Attributable to Ordinary Shareholders In contemplation of an initial public offering, or IPO, the Company has presented unaudited pro forma basic and diluted net loss per share attributable to ordinary shareholders for the year ended December 31, 2019. Unaudited pro forma basic net loss per share attributable to ordinary shareholders as of December 31, 2019 is computed to give effect to adjustments to the denominator in the pro forma basic and diluted net loss per share calculation to reflect the conversion of all of the Company’s outstanding convertible preferred shares and cumulative dividends into 11,253,839 ordinary shares, as if the conversion had occurred as of the beginning of the period or the original date of issuance, if later. Unaudited pro forma diluted net loss attributable to ordinary shareholders is the same as unaudited pro forma basic net loss per share attributable to ordinary shareholders for the period as the impact of any potentially dilutive securities was anti-dilutive, which has been computed to give effect to the adjustment noted above. The pro forma net loss per share attributable to ordinary shareholders does not include proceeds to be received from nor does it include shares expected to be sold in the assumed IPO.
Recent Accounting Pronouncements			Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board, or FASB, or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s financial position or results of operations upon adoption. In February 2016, the FASB issued ASU No. 2016-02 Leases 2016-02). 2016-02 No. 2016-02 No. 2019-10, No. 2016-02 non-public In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses No. 2020-02 In December 2019, the FASB issued ASU No. 2019-12, Income Taxes 2019-12
New Accounting Pronouncements Recently Adopted			New Accounting Pronouncements Recently Adopted In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows 2016-18 In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share Distinguishing Liabilities from Equity No. 2017-11 2017-11
Series B Preferred Stock
Convertible Preferred Stock Warrant Liability		Series B Convertible Preferred Stock Warrant Liability The Company has issued freestanding warrants to purchase its Series B convertible preferred stock. Freestanding warrants for the Company’s convertible preferred stock that are classified outside of permanent equity are recorded at fair value, and are subject to re-measurement paid-in paid-in re-measurement
Series B Preferred Stock | Predecessor Company
Convertible Preferred Stock Warrant Liability			Series B Convertible Preferred Shares Warrant Liability The Company has issued freestanding warrants to purchase its Series B convertible preferred shares. Freestanding warrants for the Company’s convertible preferred shares that are classified outside of permanent equity are recorded at fair value, and are subject to re-measurement paid-in

Organization and summary of s_3

Organization and summary of significant accounting policies (Tables)	12 Months Ended
	Dec. 31, 2019
Predecessor Company
Schedule of Useful Lives of the Property and Equipment	The useful lives of the property and equipment are as follows: Research and development equipment 5 years Furniture and office equipment 5 years Computer equipment 3 years Software 3 years Leasehold improvements Shorter of 7 years or remaining of lease term

Fair Value Of Financial Instr_2

Fair Value Of Financial Instruments (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Financial Liabilities Measured at Fair Value on Recurring Basis	The following table sets forth the Company’s financial liabilities that are measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): AS OF DECEMBER 31, 2019 LEVEL 1 LEVEL 2 LEVEL 3 FAIR VALUE Financial liabilities Non-current Compound derivative liability $ — — 51 $ 51 Warrant liability $ — — 361 $ 361 AS OF SEPTEMBER 30, 2020 LEVEL 1 LEVEL 2 LEVEL 3 FAIR VALUE Financial assets Cash equivalents Money market funds $ 90,114 — — $ 90,114 Financial liabilities Non-current Compound derivative liability $ — — 43 $ 43
Reconciliation of Financial Liabilities Measured at Fair Value Using Level 3 Unobservable Inputs	The following table is a reconciliation of all financial liabilities measured at fair value using Level 3 unobservable inputs (in thousands): WARRANT COMPOUND Fair value at December 31, 2019 $ 361 $ 51 Change in fair value 658 (8 ) Reclassification to equity (1,019 ) — Fair value at September 30, 2020 $ — $ 43
Predecessor Company
Financial Liabilities Measured at Fair Value on Recurring Basis		The following table sets forth the Company’s financial liabilities that are measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): AS OF DECEMBER 31, 2019 LEVEL 1 LEVEL 2 LEVEL 3 FAIR VALUE Financial liabilities Long term liabilities Compound derivative liability $ — — 51 $ 51 Warrant liability $ — — 361 $ 361
Reconciliation of Financial Liabilities Measured at Fair Value Using Level 3 Unobservable Inputs		The following tables are a reconciliation of all financial liabilities measured at fair value using Level 3 unobservable inputs (in thousands): WARRANT COMPOUND Balance as of December 31, 2018 $ — $ — Additions 361 51 Change in market value — — Balance as of December 31, 2019 $ 361 $ 51

Balance Sheet Components (Table

Balance Sheet Components (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Schedule of Components of Property and Equipment	The following table presents the components of property and equipment, net as of December 31, 2019 and September 30, 2020 (in thousands): DECEMBER 31, SEPTEMBER 30, Computer hardware and software $ 146 $ 74 Machinery and equipment 1,698 40 Furniture and fixtures 36 9 Leasehold improvements 429 19 2,309 142 Less: accumulated depreciation and amortization (1,449 ) (97 ) Total property and equipment, net $ 860 $ 45
Components of Accrued Expenses and Other Current Liabilities	The following table presents the components of accrued expenses and other current liabilities as of December 31, 2019 and September 30, 2020 (in thousands): DECEMBER 31, SEPTEMBER 30, Accrued professional fees $ 122 $ 345 Accrued compensation 924 1,124 Accrued clinical and nonclinical study costs — 629 Accrued contract manufacturing 53 867 Other 137 240 Total accrued expenses and other current liabilities $ 1,236 $ 3,205
Predecessor Company
Schedule of Components of Property and Equipment		The following table presents the components of property and equipment, net as of December 31, 2018 and December 31, 2019 (in thousands): DECEMBER 31, 2018 2019 Computer hardware and software $ 117 $ 146 Machinery and equipment 1,374 1,698 Furniture and fixtures 36 36 Leasehold improvements 429 429 Construction in progress 20 — 1,976 2,309 Less: accumulated depreciation and amortization (1,020 ) (1,449 ) Total property and equipment, net $ 956 $ 860
Components of Accrued Expenses and Other Current Liabilities		The following table presents the components of accrued expenses and other current liabilities as of December 31, 2018 and December 31, 2019 (in thousands): DECEMBER 31, 2018 2019 Payroll and related liabilities $ 62 $ 60 Accrued bonus 745 864 Accrued legal costs 98 122 Early exercise liability 105 27 Other 166 163 Total accrued expenses and other current liabilities $ 1,176 $ 1,236

Term Loan (Tables)

Term Loan (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Schedule of Future Payments of Principal and Interest	The following table presents future payments of principal and interest as of September 30, 2020 (in thousands): SEPTEMBER 30, 2020 (remaining three months) $ 106 2021 3,743 2022 3,007 6,856 Less: amount representing interest $ (496 ) Less: amount representing final payment (360 ) Term loan, principal amount 6,000 Less: unamortized issuance costs and debt discounts (240 ) Less: current portion (2,571 ) Non-current $ 3,189
Predecessor Company
Schedule of Future Payments of Principal and Interest		For future payments of principal and interest as of December 31, 2019 is as follows. YEAR ENDING DECEMBER 31: 2020 $ 401 2021 3,743 2022 3,007 7,151 Less: amount representing interest $ (791 ) Less: amount representing final payment (360 ) Long-term debt, gross 6,000 Less: unamortized issuance costs and debt discounts (579 ) Less: current portion — Long-term portion of term loan $ 5,421

Capital Structure (Tables)

Capital Structure (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Common Stock Reserved for Future Issuance on Converted Basis	Common stock reserved for future issuance, on an as if converted basis, as of December 31, 2019 and September 30, 2020, consists of the following: DECEMBER 31, SEPTEMBER 30, Convertible preferred stock issued and outstanding 10,313,808 — Stock options issued and outstanding 1,183,745 4,751,589 Stock options authorized for future issuance 566,900 2,941,162 Warrants issued and outstanding 61,292 — Warrants authorized for future issuance 30,646 — Total 12,156,391 7,692,751
Summary of Convertible Preferred Stock	As of December 31, 2019, the Company’s convertible preferred stock consisted of the following (in thousands, except share amounts): DECEMBER 31, 2019 AUTHORIZED SHARES NET (1) AGGREGATE Shares designated as: Series A convertible preferred stock 9,421,633 9,297,081 $ 60,933 $ 73,571 Series B convertible preferred stock 2,145,370 1,016,727 9,430 10,014 Total 11,567,003 10,313,808 $ 70,363 $ 83,585 (1) Net proceeds are gross proceeds from the offerings net of issuance costs
Predecessor Company
Common Stock Reserved for Future Issuance on Converted Basis		Ordinary shares reserved for future issuance, on an as if converted basis, as of December 31, 2018 and December 31, 2019, consists of the following: DECEMBER 31, 2018 2019 Convertible preferred shares, issued and outstanding 9,297,081 10,313,808 Share options, issued and outstanding 864,819 1,183,745 Share options, authorized for future issuance 73,015 566,900 Warrants, issued and outstanding — 61,292 Warrants, authorized for future issuance — 30,646 Total 10,234,915 12,156,391
Summary of Convertible Preferred Stock		As of December 31, 2018 and December 31, 2019, the Company’s convertible preferred shares consisted of the following (in thousands, except share amounts): DECEMBER 31, 2018 AUTHORIZED SHARES NET (1) AGGREGATE Shares designated as: Series A convertible preferred shares 9,421,633 9,297,081 $ 60,933 $ 69,863 Total 9,421,633 9,297,081 $ 60,933 $ 69,863 DECEMBER 31, 2019 AUTHORIZED SHARES NET (1) AGGREGATE Shares designated as: Series A convertible preferred shares 9,421,633 9,297,081 $ 60,933 $ 73,571 Series B convertible preferred shares 2,145,370 1,016,727 9,430 10,014 Total 11,567,003 10,313,808 $ 70,363 $ 83,585 (1) Net proceeds are gross proceeds from the offerings net of issuance costs.

Share-Based Compensation (Table

Share-Based Compensation (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Summary of Total Stock Based Compensation Expense	Total stock-based compensation expense recognized in the condensed consolidated statements of operations and comprehensive loss was as follows (in thousands): THREE MONTHS ENDED NINE MONTHS ENDED 2019 2020 2019 2020 Research and development $ 25 $ (359 ) $ 79 $ 2,008 General and administrative 10 1,048 24 1,685 Cost of services for related-party revenue 51 — 119 — $ 86 $ 689 $ 222 $ 3,693
Predecessor Company
Summary of Share Option Activity		The following table provides a summary of share option activity under the Plan and related information: OUTSTANDING OPTIONS SHARES NUMBER WEIGHTED WEIGHTED AGGREGATE (in thousands) Balance outstanding at December 31, 2017 218,322 719,527 $ 0.99 9.18 $ — Granted (187,186 ) 187,186 $ 1.85 Exercised — (6,914 ) $ 0.99 Canceled/forfeited 34,980 (34,980 ) $ 0.99 Shares repurchased 6,899 — — Balance outstanding at December 31, 2018 73,015 864,819 $ 1.17 8.54 $ 582 Authorized 818,010 Granted (341,871 ) 341,871 $ 1.91 Exercised — (5,199 ) $ 1.86 Canceled/forfeited 17,746 (17,746 ) $ 1.88 Balance outstanding at December 31, 2019 566,900 1,183,745 $ 1.37 8.06 $ 638 Exercisable at December 31, 2019 565,975 $ 1.16 7.56 $ 424
Summary of Total Stock Based Compensation Expense		Share-based compensation expense includes share options granted to employees and nonemployees and has been reported in the Company’s consolidated statements of operations and comprehensive loss as follows (in thousands): YEAR ENDED DECEMBER 31, 2018 2019 Research and development $ 195 $ 105 General and administrative 16 33 Cost of services for related-party revenue 58 159 Total $ 269 $ 297
Schedule of Fair Value of Each Option Grant Using Black-Scholes Option-Pricing Model		The fair value of each option grant during the years ended December 31, 2018 and December 31, 2019 was estimated on the date of grant using the Black-Scholes option-pricing model with the following: YEAR ENDED DECEMBER 31, 2018 2019 Expected term (in years) 5.2 – 6.0 4.4 – 6.0 Risk-free interest rate 2.6% – 3.0% 1.7% – 2.1% Expected dividend rate – – Expected share price volatility 66.5% – 68.7% 75.2% – 80.5%
Founder Stock | Predecessor Company
Summary of Share Option Activity		The following table provides a summary of Founder Stock activity: NUMBER OF WEIGHTED-AVERAGE Unvested at December 31, 2017 455,477 $0.35 Vested (341,613 ) 0.35 Unvested at December 31, 2018 113,864 0.35 Vested (113,864 ) 0.35 Unvested at December 31, 2019 — $ —

Income Taxes (Tables)

Income Taxes (Tables) - Predecessor Company	12 Months Ended
	Dec. 31, 2019
Schedule Components of Loss Before Income Taxes	The domestic (Ireland) and foreign components of pre-tax DECEMBER 31, 2018 2019 Foreign $ (12,576 ) $ (16,803 ) Domestic (Ireland) (1,110 ) (2,406 ) Loss before income taxes $ (13,686 ) $ (19,209 )
Schedule Of Income Tax Provision (Benefit)	The provision for income taxes consist of the following (in thousands): YEAR ENDED 2018 2019 Current Domestic (Ireland) $ — $ — State (U.S.) 1 1 Foreign/federal 44 33 Total current 45 34 Deferred Domestic (Ireland) $ — $ — State (U.S.) — — Foreign/federal — — Total deferred — — Provision for income taxes $ 45 $ 34
Schedule of Statutory and Effective Income Tax Rate Reconciliation	A reconciliation of the Irish statutory income tax rate of 12.5% to the actual tax rate for the years ended December 31, 2018 and December 31, 2019 are as follows (in thousands): YEAR ENDED 2018 2019 At statutory rate $ (1,711 ) $ (2,401 ) Foreign income tax at different rates 1,404 378 U.S. R&D credits (499 ) (861 ) Change in valuation allowance 732 3,733 Share-based compensation 57 60 Prior period true ups (38 ) (950 ) Other 100 75 Provision for income taxes $ 45 $ 34
Schedule of Components of Deferred Tax Assets	Significant components of the Company’s deferred tax assets as of December 31, 2018 and December 31, 2019 are as follows (in thousands): DECEMBER 31, 2018 2019 Deferred tax assets: Net operating loss carryforwards $ 363 $ 3,259 Research & other credits 1,701 3,260 Other 208 333 Total gross DTA $ 2,272 $ 6,852 Less: Val. Allowance (2,181 ) (6,686 ) Total deferred tax assets $ 91 $ 166 Deferred tax liabilities: Fixed assets $ (91 ) $ 166 Total gross DTL $ (91 ) $ 166 Net deferred tax assets $ — $ —
Schedule of Unrecognized Tax Benefits	The Company has the following activity relating to unrecognized tax benefits (in thousands): DECEMBER 31, 2018 2019 Beginning balance $ 247 $ 418 Gross increase—tax positions in prior periods 11 9 Gross decreases—tax positions in prior periods — (7 ) Gross increases—tax positions in prior periods 160 272 Ending balance $ 418 $ 692

Commitments & Contingencies (Ta

Commitments & Contingencies (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Summary of Company's Commitments and Contractual Obligations	The Company has contractual obligations from its operating lease, manufacturing and service contracts, Term Loan, and other research and development activities. The following table aggregates the Company’s material expected contractual obligations and commitments as of September 30, 2020 (in thousands): SEPTEMBER 30, 2020 TOTAL 2020 (4) 2021 - 2022 2023 - 2024 THEREAFTER Operating lease obligations (1) $ 380 $ 34 $ 284 $ 62 $ — Manufacturing and service contracts (2) 7,622 6,238 1,384 — — Term loan (3) 6,856 106 6,750 — — Total $ 14,858 $ 6,378 $ 8,418 $ 62 $ — (1) Payments due for the office space in Burlingame, California under a single operating sub-lease (2) In November 2015, the Company entered into a Master Service Agreement, or the MSA, with KBI Biopharma, Inc. relating to formulation development, process development and cGMP manufacturing of ALX148 for use in clinical trials on a project basis. The MSA had an initial term of three years with successive one-year non-exclusive. non-cancellable (3) On December 20, 2019, the Company borrowed a loan pursuant to the Loan Agreement. See Note 5 to these condensed consolidated financial statements for additional details. (4) Remaining three months.
Predecessor Company
Summary of Company's Commitments and Contractual Obligations		The following table summarizes the Company’s commitments and contractual obligations as of December 31, 2019 (in thousands): YEAR ENDED DECEMBER 31: OPERATING MANUFACTURING (2) TERM LOAN 2020 $ 544 $ 926 $ 401 2021 560 5,805 3,743 2022 577 — 3,007 2023 247 — — Total $ 1,928 $ 6,731 $ 7,151 (1) Payments due for the office and laboratory space in Burlingame, California under a single operating lease agreement that expires in 2023. (2) These amounts are based on non-cancellable (3) In December 2019, the Company entered into a term loan pursuant to the Loan Agreement as described above in Note 4.

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable To Common Stockholders (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Computation of Basic and Diluted Net Loss per Share	The following table sets forth the computation of the basic and diluted net loss per share attributable to common stockholders (in thousands, except share and per share data): THREE MONTHS ENDED NINE MONTHS ENDED 2019 2020 2019 2020 Numerator: Net loss $ (3,044 ) $ (10,181 ) $ (11,479 ) $ (26,966 ) Less: cumulative preferred dividends allocated to preferred stockholders (1,071 ) (578 ) (2,957 ) (5,202 ) Net loss attributable to common stockholders $ (4,115 ) $ (10,759 ) $ (14,436 ) $ (32,168 ) Denominator: Weighted-average shares of common stock outstanding 3,100,544 29,664,122 3,061,082 12,052,876 Net loss per share attributable to common stockholders, basic and diluted $ (1.33 ) $ (0.36 ) $ (4.72 ) $ (2.67 )
Summary of Outstanding Potentially Dilutive Securities Were Excluded from Computation of Diluted Net Loss Per Share	The following outstanding potentially dilutive securities were excluded from the computation of diluted net loss per share for the three and nine months ended September 30, 2019 and 2020, because including them would have been anti-dilutive: SEPTEMBER 30, 2019 2020 Convertible preferred stock 10,313,808 — Common stock subject to repurchase 53,070 253 Options issued and outstanding 1,206,690 4,751,589 Total 11,573,568 4,751,842
Predecessor Company
Computation of Basic and Diluted Net Loss per Share		The following table sets forth the computation of the basic and diluted net loss per share attributable to ordinary shareholders (in thousands, except share and per share data): YEAR ENDED DECEMBER 31, 2018 2019 Numerator: Net loss $ (13,731 ) $ (19,243 ) Less: cumulative dividends allocated to preferred shareholders (3,671 ) (4,028 ) Net loss attributable to ordinary shareholders $ (17,402 ) $ (23,271 ) Denominator: Weighted-average ordinary shares outstanding 2,750,838 3,076,461 Net loss per share attributable to ordinary shareholders, basic and diluted $ (6.33 ) $ (7.56 )
Summary of Outstanding Potentially Dilutive Securities Were Excluded from Computation of Diluted Net Loss Per Share		Potentially dilutive securities that were not included in the diluted per share calculations as of December 31, 2018 and December 31, 2019 because they would be anti-dilutive were as follows: DECEMBER 31, 2018 2019 Series A convertible preferred shares 9,297,081 9,297,081 Series B convertible preferred shares — 1,016,727 Warrants to purchase convertible preferred shares — 61,292 Ordinary shares subject to repurchase 229,912 34,024 Options issued and outstanding 864,819 1,183,745 Total 10,391,812 11,592,869
Computation of Unaudited Pro Forma Basic and Diluted Net Loss per Share		The following table sets forth the computation of the Company’s unaudited pro forma basic and diluted net loss per share (in thousands, except share and per share amounts): YEAR ENDED Net loss $ (19,243 ) Weighted-average ordinary shares used in computing net loss per share attributable to ordinary shareholders, basic and diluted 3,076,461 Pro forma adjustment to reflect assumed conversion of preferred shares and accrued dividends allocable to ordinary shareholders 11,253,839 Weighted-average ordinary shares used to compute pro forma net loss per share, basic and diluted 14,330,300 Pro forma net loss per share, basic and diluted $ (1.34 )

Stockholders Equity - Additiona

Stockholders Equity - Additional Information (Detail) - $ / shares	Sep. 30, 2020	Aug. 17, 2020	Jul. 21, 2020	Apr. 01, 2020	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
Common stock, par value	$ 0.001			$ 0.001	$ 0.001
Common stock, shares authorized	1,000,000,000		1,000,000,000	151	1,519,618,271
Common stock, shares issued	37,107,522	48,932		0	3,166,946
Common stock, shares outstanding	37,107,522			0	3,166,946

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail)	Jul. 08, 2020	Apr. 01, 2020USD ($)$ / sharesshares	Feb. 29, 2020USD ($)$ / sharesshares	Sep. 30, 2020shares	Dec. 31, 2019shares	Aug. 17, 2020shares	Jul. 21, 2020shares	Dec. 31, 2018shares	Dec. 31, 2015shares
Subsequent Event [Line Items]
Common stock, shares authorized		151		1,000,000,000	1,519,618,271		1,000,000,000
Convertible preferred stock, shares authorized					11,567,003
Common stock, shares issued		0		37,107,522	3,166,946	48,932
Exchange for promissory notes with aggregate principal amount | $		$ 176,300,000
Acquired ordinary shares for exchange for promissory notes with aggregate principal amount | $		$ 525,000,000
Reverse stock split, description				On July 8, 2020, the Company's board of directors approved an amendment to the Company's certificate of incorporation to effect a 1-for-6.5806 reverse split of its common stock and convertible preferred stock.
Reverse stock split, conversion ratio	0.151961827
Predecessor Company
Subsequent Event [Line Items]
Common stock, shares authorized					1,519,618,271			1,519,618,271
Convertible preferred stock, shares authorized					11,567,003			9,421,633
Common stock, shares issued					3,166,946			3,161,747	2,127,460
Reverse stock split, description					On July 8, 2020, the Company's board of directors approved an amendment to ALX Oncology Holdings Inc.'s certificate of incorporation to effect a 1-for-6.5806 reverse split of its ordinary shares and convertible preferred shares.
Two Thousand Twenty Equity Incentive Plan [Member]
Subsequent Event [Line Items]
Award of stock options authorized		4,379,139
Series A Convertible Preferred Stock
Subsequent Event [Line Items]
Convertible preferred stock, shares authorized		9,297,100		0	9,421,633
Stock price per share | $ / shares		$ 6.58
Convertible preferred stock, shares issued		9,297,081		0	9,297,081
Series A Convertible Preferred Stock | Predecessor Company
Subsequent Event [Line Items]
Convertible preferred stock, shares authorized					9,421,633			9,421,633
Convertible preferred stock, shares issued					9,297,081			9,297,081
Series B Convertible Preferred Stock
Subsequent Event [Line Items]
Convertible preferred stock, shares authorized		1,108,675		0	2,145,370
Stock price per share | $ / shares		$ 9.4972
Convertible preferred stock, shares issued		1,016,727		0	1,016,727
Series B Convertible Preferred Stock | Predecessor Company
Subsequent Event [Line Items]
Convertible preferred stock, shares authorized					2,145,370			2,145,370
Convertible preferred stock, shares issued					1,016,727			0
Series C Convertible Preferred Stock
Subsequent Event [Line Items]
Convertible preferred stock, shares authorized		11,055,981
Stock price per share | $ / shares		$ 9.4972
Convertible preferred stock, shares issued		11,055,966
Series C Convertible Preferred Stock | Predecessor Company | Subsequent Event
Subsequent Event [Line Items]
Convertible preferred stock, shares authorized			11,055,981
Stock price per share | $ / shares			$ 9.4972
Proceeds from issuance of preferred stock | $			$ 105,000,000
Common Stock | Minimum
Subsequent Event [Line Items]
Stock price per share | $ / shares		$ 0.007
Common Stock | Maximum
Subsequent Event [Line Items]
Stock price per share | $ / shares		$ 1.91

Organization and Summary of S_4

Organization and Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)Subsidiaryshares	Dec. 31, 2018USD ($)	Apr. 01, 2020USD ($)
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit	$ (99,748,000)		$ (99,748,000)		$ (72,782,000)
Cash and cash equivalents	259,484,000		259,484,000		$ 9,017,000
Gross proceeds from the issuance of preferred shares			36,228,000	$ 2,601,000
Impairment charges recognized	$ 0	$ 0	$ 0	$ 0
Predecessor Company
Summary Of Significant Accounting Policies [Line Items]
Number of indirect subsidiaries | Subsidiary					2
Accumulated deficit					$ (72,782,000)	$ (53,539,000)
Cash and cash equivalents					9,017,000	8,262,000
Gross proceeds from the issuance of preferred shares					5,917,000
Impairment charges recognized					$ 0	$ 0
Pro forma basic and diluted net loss per share, shares and dividend into ordinary shares adjustment | shares					11,253,839
Predecessor Company | Series C Convertible Preferred Stock
Summary Of Significant Accounting Policies [Line Items]
Gross proceeds from the issuance of preferred shares					$ 105,000,000

Disclosure - Organization and S

Disclosure - Organization and Summary of Significant Accounting Policies - Schedule of Useful Lives of the Property and Equipment (Detail) - Predecessor Company	12 Months Ended
	Dec. 31, 2019
Research and development equipment
Property, Plant and Equipment [Line Items]
Useful life of property plant and equipment	5 years
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Useful life of property plant and equipment	5 years
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Useful life of property plant and equipment	3 years
Software Development [Member]
Property, Plant and Equipment [Line Items]
Useful life of property plant and equipment	3 years
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Useful life of property plant and equipment	Shorter of 7 years or remaining of lease term

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Financial Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value on Recurring Basis - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financial liabilities
Compound derivative liability	$ 43	$ 51
Warrant liability		361
Money Market Funds
Financial liabilities
Money market funds	90,114
Level 1 | Money Market Funds
Financial liabilities
Money market funds	90,114
Level 3
Financial liabilities
Compound derivative liability	$ 43	51
Warrant liability		361
Predecessor Company
Financial liabilities
Compound derivative liability		51
Warrant liability		361
Predecessor Company | Level 3
Financial liabilities
Compound derivative liability		51
Warrant liability		$ 361

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Reconciliation of Financial Liabilities Measured at Fair Value Using Level 3 Unobservable Inputs (Detail) - Level 3 - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Warrant Liability
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, beginning balance	$ 361
Change in fair value	658
Reclassification to equity	(1,019)
Fair value, ending balance		$ 361
Compound Derivative Liability
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, beginning balance	51
Change in fair value	(8)
Fair value, ending balance	43	51
Predecessor Company | Warrant Liability
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, beginning balance	361
Additions		361
Fair value, ending balance		361
Predecessor Company | Compound Derivative Liability
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value, beginning balance	$ 51
Additions		51
Fair value, ending balance		$ 51

Fair Value of Financial Instr_5

Fair Value of Financial Instruments - Additional Information (Detail)	9 Months Ended	12 Months Ended
	Sep. 30, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value assets transferred from level 1 to level 2	$ 0	$ 0
Fair value assets transferred from level 2 to level 1	0	0
Fair value liabilities transferred from level 1 to level 2	0	0
Fair value liabilities transferred from level 2 to level 1	0	0
Fair value assets transferred into level 3	0	0
Fair value assets transferred out of level 3	0	0
Fair value liabilities transferred into level 3	0	0
Fair value liabilities transferred out of level 3	$ 0	0
Discount Rate | Term Loan
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Valuation assumptions rate	12
Probability of Occurrence | Term Loan
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Valuation assumptions rate	20
Level 3 | Market Yield Analysis and Income Approach | Term Loan
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Estimated fair value	$ 6,100,000
Predecessor Company
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value assets transferred from level 1 to level 2		0	$ 0
Fair value assets transferred from level 2 to level 1		0	0
Fair value liabilities transferred from level 1 to level 2		0	0
Fair value liabilities transferred from level 2 to level 1		0	0
Fair value assets transferred into level 3		0	0
Fair value assets transferred out of level 3		0	0
Fair value liabilities transferred into level 3		0	0
Fair value liabilities transferred out of level 3		$ 0	$ 0
Predecessor Company | Discount Rate | Term Loan
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Valuation assumptions rate		14.5
Predecessor Company | Probability of Occurrence | Term Loan
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Valuation assumptions rate		10
Predecessor Company | Level 3 | Market Yield Analysis and Income Approach | Term Loan
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Estimated fair value		$ 5,700,000

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Components of Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Apr. 01, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 142		$ 2,309
Less: accumulated depreciation and amortization	(97)		(1,449)
Total property and equipment, net	45		860
Computer Hardware And Software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	74		146
Machinery and Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	40		1,698
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	9		36
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 19		429
Predecessor Company
Property, Plant and Equipment [Line Items]
Property and equipment, gross			2,309	$ 1,976
Less: accumulated depreciation and amortization			(1,449)	(1,020)
Total property and equipment, net			860	956
Predecessor Company | Computer Hardware And Software
Property, Plant and Equipment [Line Items]
Property and equipment, gross			146	117
Predecessor Company | Machinery and Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross			1,698	1,374
Predecessor Company | Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross			36	36
Predecessor Company | Leasehold Improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross			$ 429	429
Predecessor Company | Construction in Progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross				$ 20

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Detail) - USD ($) $ in Thousands	Jul. 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Jun. 30, 2020	Apr. 01, 2020
Depreciation and amortization expense		$ 0	$ 100	$ 200	$ 300
Property and equipment		$ 45		$ 45		$ 860
Lab Equipment and Other Assets
Property and equipment								$ 600
Proceeds from transfer of assets for cash	$ 600
Predecessor Company
Depreciation and amortization expense						400	$ 400
Property and equipment						$ 860	$ 956

Balance Sheet Components - Comp

Balance Sheet Components - Components of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Apr. 01, 2020	Dec. 31, 2019	Dec. 31, 2018
Balance Sheet Related Disclosures
Accrued professional fees	$ 345		$ 122
Accrued compensation	1,124		924
Accrued clinical and nonclinical study costs	629
Accrued contract manufacturing	867		53
Other	240		137
Total accrued expenses and other current liabilities	$ 3,205		1,236
Predecessor Company
Balance Sheet Related Disclosures
Payroll and related liabilities			60	$ 62
Accrued bonus			864	745
Accrued professional fees			122	98
Early exercise liability			27	105
Other			163	166
Total accrued expenses and other current liabilities			$ 1,236	$ 1,176

Term Loan - Additional Informat

Term Loan - Additional Information (Detail)	Aug. 17, 2020$ / sharesshares	Dec. 20, 2019USD ($)$ / sharesshares	Sep. 30, 2020USD ($)shares	Sep. 30, 2020USD ($)	Dec. 31, 2019USD ($)$ / shares	Jul. 21, 2020$ / sharesshares	Jul. 16, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2018$ / shares
Debt Instrument [Line Items]
Warrant exercise | shares	61,292
Warrant exercise price per share | $ / shares	$ 9.4972
Unamortized issuance costs and debt discounts			$ 240,000	$ 240,000
Interest expense for term loan			$ 300,000	700,000
Common Stock
Debt Instrument [Line Items]
Warrants to purchase common stock | shares						61,292
Common stock exercise price per share | $ / shares						$ 9.4972
Stock issued upon warrants exercise | shares			21,369,774
Series B Convertible Preferred Stock
Debt Instrument [Line Items]
Warrant exercise | shares						61,292
Warrant exercise price per share | $ / shares						$ 9.4972
Compound Derivative Liability
Debt Instrument [Line Items]
Fair value of compound derivative liability		$ 51,000
Compound Derivative Liability | Other Noncurrent Liabilities
Debt Instrument [Line Items]
Fair value of compound derivative liability			$ 43,000	$ 43,000
Predecessor Company
Debt Instrument [Line Items]
Unamortized issuance costs and debt discounts					$ 579,000
Common stock exercise price per share | $ / shares					$ 1.91				$ 1.85
Predecessor Company | Compound Derivative Liability
Debt Instrument [Line Items]
Fair value of compound derivative liability		$ 51,000
Predecessor Company | Compound Derivative Liability | Other Noncurrent Liabilities
Debt Instrument [Line Items]
Fair value of compound derivative liability					$ 51,000
Loan Agreement
Debt Instrument [Line Items]
Term loan, annual floating interest rate		7.00%
Term loan, interest rate				7.00%
Term loan interest-only payments, term				Interest-only payments for the first 12 months after the closing of the Loan Agreement
Percentage of principal amount as final payment		6.00%
Warrant exercise | shares		61,292
Warrant exercise price per share | $ / shares		$ 9.4972
Loan Agreement | Common Stock
Debt Instrument [Line Items]
Warrants to purchase common stock | shares		61,292
Common stock exercise price per share | $ / shares		$ 9.4972
Stock issued upon warrants exercise | shares	48,932
Loan Agreement | Series B Convertible Preferred Stock
Debt Instrument [Line Items]
Warrant exercise | shares	61,292
Warrant exercise price per share | $ / shares	$ 9.4972
Estimated fair value of warrants		$ 400,000
Outstanding preferred stock warrant liability converted into common stock							$ 1,000,000
Loan Agreement | Maximum
Debt Instrument [Line Items]
Term loan, principal amount		$ 10,000,000
Prepayment fee percentage		3.00%
Loan Agreement | Minimum
Debt Instrument [Line Items]
Proceeds from equity financing		$ 30,000,000
Prepayment fee percentage		1.00%
Loan Agreement | Predecessor Company
Debt Instrument [Line Items]
Term loan, annual floating interest rate		7.00%
Term loan, interest rate					7.00%
Term loan interest-only payments, term					Interest-only payments for the first 12 months after the closing of the Loan Agreement
Percentage of principal amount as final payment		6.00%
Warrant exercise | shares		61,292
Warrant exercise price per share | $ / shares		$ 9.4972
Estimated fair value of warrants					$ 400,000
Equity value					$ 345,000,000
Loan Agreement | Predecessor Company | Series B Convertible Preferred Stock
Debt Instrument [Line Items]
Estimated fair value of warrants		$ 400,000
Loan Agreement | Predecessor Company | Maximum
Debt Instrument [Line Items]
Term loan, principal amount		$ 10,000,000
Prepayment fee percentage		3.00%
Loan Agreement | Predecessor Company | Minimum
Debt Instrument [Line Items]
Proceeds from equity financing		$ 30,000,000
Prepayment fee percentage		1.00%
Loan Agreement | Prime Rate
Debt Instrument [Line Items]
Term loan, interest rate above prime rate		2.00%
Percentage of prime rate				3.25%
Loan Agreement | Prime Rate | Predecessor Company
Debt Instrument [Line Items]
Term loan, interest rate above prime rate		2.00%
Percentage of prime rate					4.75%
Loan Agreement | Time to Liquidity | Maximum | Series B Convertible Preferred Stock
Debt Instrument [Line Items]
Warrants and rights outstanding, measurement input term							9 years 9 months 18 days
Loan Agreement | Time to Liquidity | Minimum | Series B Convertible Preferred Stock
Debt Instrument [Line Items]
Warrants and rights outstanding, measurement input term			2 years	2 years
Loan Agreement | Time to Liquidity | Predecessor Company | Maximum | Series B Convertible Preferred Stock
Debt Instrument [Line Items]
Warrants and rights outstanding, measurement input term					10 years
Loan Agreement | Time to Liquidity | Predecessor Company | Minimum | Series B Convertible Preferred Stock
Debt Instrument [Line Items]
Warrants and rights outstanding, measurement input term					2 years
Loan Agreement | Volatility | Series B Convertible Preferred Stock
Debt Instrument [Line Items]
Warrants and rights outstanding, measurement input							0.842
Loan Agreement | Volatility | Predecessor Company | Series B Convertible Preferred Stock
Debt Instrument [Line Items]
Warrants and rights outstanding, measurement input					0.855
Loan Agreement | Risk-free Rate | Series B Convertible Preferred Stock
Debt Instrument [Line Items]
Warrants and rights outstanding, measurement input							0.006
Loan Agreement | Risk-free Rate | Predecessor Company | Series B Convertible Preferred Stock
Debt Instrument [Line Items]
Warrants and rights outstanding, measurement input					0.017
Loan Agreement | Dividend Rate | Series B Convertible Preferred Stock
Debt Instrument [Line Items]
Warrants and rights outstanding, measurement input							0
First Tranche | Loan Agreement
Debt Instrument [Line Items]
Term loan, principal amount					$ 6,000,000
First Tranche | Loan Agreement | Predecessor Company
Debt Instrument [Line Items]
Term loan, principal amount					$ 6,000,000
Second Tranche | Loan Agreement
Debt Instrument [Line Items]
Term loan, principal amount								$ 4,000,000
Second Tranche | Loan Agreement | Predecessor Company
Debt Instrument [Line Items]
Term loan, principal amount								$ 4,000,000

Term Loan - Schedule of Future

Term Loan - Schedule of Future Payments of Principal and Interest (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Apr. 01, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
2020 (remaining three months)	$ 106
2020	3,743
2021	3,007
Future payments of principal and interest	6,856
Less: amount representing interest	(496)
Less: amount representing final payment	(360)
Term loan, principal amount	6,000
Less: unamortized issuance costs and debt discounts	(240)
Less: current portion	(2,571)
Non-current portion of term loan	$ 3,189		$ 5,421
Predecessor Company
Debt Instrument [Line Items]
2020			401
2021			3,743
2022			3,007
Future payments of principal and interest			7,151
Less: amount representing interest			(791)
Less: amount representing final payment			(360)
Term loan, principal amount			6,000
Less: unamortized issuance costs and debt discounts			(579)
Non-current portion of term loan			$ 5,421

Capital Structure - Additional

Capital Structure - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jul. 21, 2020	Jul. 20, 2020	Dec. 31, 2019	Jul. 31, 2020	Sep. 30, 2017	Sep. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2016	Aug. 17, 2020	Apr. 01, 2020	May 31, 2019	Dec. 31, 2015	May 31, 2015
Class of Stock [Line Items]
Common stock, shares, issued			3,166,946			37,107,522			37,107,522		3,166,946			48,932	0
Proceeds from issuance of convertible preferred stock									$ 36,228	$ 2,601
Total issuance costs									$ 3,183
Preferred stock, share outsatanding			0			0			0		0
Warrants issued to purchase														61,292
Warrant exercise price per share														$ 9.4972
Common Stock
Class of Stock [Line Items]
Shares issued						9,775,000
Warrants to purchase common stock	61,292
Common stock exercise price per share	$ 9.4972
Predecessor Company
Class of Stock [Line Items]
Common stock, shares, issued			3,166,946								3,166,946	3,161,747					2,127,460
Share price																	$ 0.033
Shares subject to repurchase			0								0	113,864
Proceeds from issuance of convertible preferred stock											$ 5,917
Total issuance costs											$ 2,601
Contingent mandatory conversion											Upon the closing of the first underwritten public offering pursuant to an effective registration statement under the Securities Act of 1933, as amended, or pursuant to a corresponding securities issuance application process in any non-U.S. jurisdiction, covering the offer and sale of the Company’s ordinary shares in which (i) the per share price is not less than $15.19540 (as adjusted for any share dividends, combinations, splits, recapitalizations and the like with respect to such shares after the filing date hereof) and (ii) the gross cash proceeds to the Company (before underwriting discounts, commissions and fees) are at least $50.0 million then all outstanding Preferred Shares shall automatically be converted into a number of ordinary shares
Common stock exercise price per share			$ 1.91								$ 1.91	$ 1.85
Approval of holder | Predecessor Company
Class of Stock [Line Items]
Preferred stock, share outsatanding			1,367,656								1,367,656
Series B Convertible Preferred Stock
Class of Stock [Line Items]
Warrants issued to purchase	61,292
Warrant exercise price per share	$ 9.4972
Convertible Preferred Stock
Class of Stock [Line Items]
Issuance of convertible preferred stock							11,055,966	1,016,727
Cumulative dividends		$ 18,000
Preferred stock, cumulative dividends percentage									6.00%
Cumulative preferred stock dividend convertible shares issued upon conversion		2,564,759
Convertible Preferred Stock | Predecessor Company
Class of Stock [Line Items]
Issuance of convertible preferred stock											1,016,727
Cumulative dividends											$ 12,700	$ 8,700
Preferred stock, cumulative dividends percentage											6.00%
Series A Convertible Preferred Stock
Class of Stock [Line Items]
Share price						$ 6.58			$ 6.58
Series A Convertible Preferred Stock | Predecessor Company
Class of Stock [Line Items]
Share price			$ 6.58								$ 6.58
Series B and C Convertible Preferred Stock
Class of Stock [Line Items]
Share price						$ 9.4972			$ 9.4972
Series A Preferred Stock | Predecessor Company
Class of Stock [Line Items]
Share price													$ 6.58
Issuance of convertible preferred stock					3,826,469								5,470,612
Proceeds from issuance of convertible preferred stock					$ 1,200								$ 34,800
Total issuance costs					200
Gross proceeds from issuance of shares					$ 37,200
Series A Preferred Stock | Predecessor Company | Series A Purchase Agreement
Class of Stock [Line Items]
Convertible preferred stock authorized for sale and issuance																		5,470,625
Series A Preferred Stock | Predecessor Company | Note Purchase Agreement
Class of Stock [Line Items]
Note, principal amount																		$ 25,000
Series B Preferred Stock | Predecessor Company
Class of Stock [Line Items]
Share price			$ 9.4972								$ 9.4972					$ 9.4972
Convertible preferred stock authorized for sale and issuance																2,145,370
Issuance of convertible preferred stock			1,016,727
Proceeds from issuance of convertible preferred stock			$ 9,600
Total issuance costs			$ 200
Initial Public Offering | Common Stock
Class of Stock [Line Items]
Total issuance costs	$ 13,000			$ 13,000
Shares issued	9,775,000			9,775,000
Net proceeds from initial public offering	$ 169,500			$ 169,500
Payment for offering related expense	$ 3,200			$ 3,200
Convertible shares converted into common stock	23,934,533			23,934,533

Capital Structure - Common Stoc

Capital Structure - Common Stock Reserved for Future Issuance on Converted Basis (Detail) - shares	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Common stock reserved for future issuance	7,692,751	12,156,391
Predecessor Company
Class of Stock [Line Items]
Common stock reserved for future issuance		12,156,391	10,234,915
Convertible Preferred Stock Issued And Outstanding
Class of Stock [Line Items]
Common stock reserved for future issuance		10,313,808
Convertible Preferred Stock Issued And Outstanding | Predecessor Company
Class of Stock [Line Items]
Common stock reserved for future issuance		10,313,808	9,297,081
Stock Options Issued And Outstanding
Class of Stock [Line Items]
Common stock reserved for future issuance	4,751,589	1,183,745
Stock Options Issued And Outstanding | Predecessor Company
Class of Stock [Line Items]
Common stock reserved for future issuance		1,183,745	864,819
Stock Options Authorized For Future Issuance
Class of Stock [Line Items]
Common stock reserved for future issuance	2,941,162	566,900
Stock Options Authorized For Future Issuance | Predecessor Company
Class of Stock [Line Items]
Common stock reserved for future issuance		566,900	73,015
Warrants Issued And Outstanding
Class of Stock [Line Items]
Common stock reserved for future issuance		61,292
Warrants Issued And Outstanding | Predecessor Company
Class of Stock [Line Items]
Common stock reserved for future issuance		61,292
Warrants Authorized For Future Issuance
Class of Stock [Line Items]
Common stock reserved for future issuance		30,646
Warrants Authorized For Future Issuance | Predecessor Company
Class of Stock [Line Items]
Common stock reserved for future issuance		30,646

Capital Structure - Summary of

Capital Structure - Summary of Convertible Preferred Stock (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Apr. 01, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Authorized Shares			11,567,003
Shares Issued And Outstanding			10,313,808
Net Proceeds			$ 70,363
Aggregate Liquidation Preference			$ 83,585
Predecessor Company
Class of Stock [Line Items]
Authorized Shares			11,567,003	9,421,633
Shares Issued And Outstanding			10,313,808	9,297,081
Net Proceeds			$ 70,363	$ 60,933
Aggregate Liquidation Preference			$ 83,585	$ 69,863
Series A Convertible Preferred Stock
Class of Stock [Line Items]
Authorized Shares	0	9,297,100	9,421,633
Shares Issued And Outstanding			9,297,081
Net Proceeds			$ 60,933
Aggregate Liquidation Preference			$ 73,571
Series A Convertible Preferred Stock | Predecessor Company
Class of Stock [Line Items]
Authorized Shares			9,421,633	9,421,633
Shares Issued And Outstanding			9,297,081	9,297,081
Net Proceeds			$ 60,933	$ 60,933
Aggregate Liquidation Preference			$ 73,571	$ 69,863
Series B Convertible Preferred Stock
Class of Stock [Line Items]
Authorized Shares	0	1,108,675	2,145,370
Shares Issued And Outstanding			1,016,727
Net Proceeds			$ 9,430
Aggregate Liquidation Preference			$ 10,014
Series B Convertible Preferred Stock | Predecessor Company
Class of Stock [Line Items]
Authorized Shares			2,145,370	2,145,370
Shares Issued And Outstanding			1,016,727
Net Proceeds			$ 9,430
Aggregate Liquidation Preference			$ 10,014	$ 0

Share- Based Compensation - Add

Share- Based Compensation - Additional Information (Detail) - USD ($)	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Jul. 31, 2020	Dec. 31, 2015
Shares reserved for future issuance	7,692,751			7,692,751		12,156,391
Stock-based compensation expenses	$ 689,000		$ 86,000	$ 3,693,000	$ 222,000
Stock Option Modification
Stock-based compensation expenses	$ 200,000	$ 2,300,000
2020 Plan
Shares reserved for future issuance								7,874,862
Predecessor Company
Unvested early exercised options						34,024	116,048
Liability related to these unvested options						$ 27,000	$ 100,000
Unrecognized share-based compensation expense						$ 0.6
Unrecognized share-based compensation expense, weighted-average period						2 years 8 months 12 days
Weighted-average grant-date fair value per share						$ 1.27	$ 1.14
Total fair value of options vested						$ 300,000	$ 100,000
Share-based compensation expense, fair value of ordinary shares						$ 1.91	$ 1.85
Shares reserved for future issuance						12,156,391	10,234,915
Stock-based compensation expenses						$ 297,000	$ 269,000
Predecessor Company | Founder Stock
Total fair value of awards vested						$ 40,000	$ 100,000
Founder Stock granted						0	0
Predecessor Company | 2015 Plan
Equity compensation plan, maximum awards available for grant									2,143,117

Share- Based Compensation - sum

Share- Based Compensation - summary of share option activity (Detail) - Predecessor Company - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shares available to grant, Balance	73,015	218,322
Shares available to grant, Authorized	818,010
Shares available to grant, Granted	(341,871)	(187,186)
Shares available to grant, Canceled/forfeited	$ 17,746	$ 34,980
Shares available to grant, Shares repurchased		6,899
Shares available to grant, Balance	566,900	73,015	218,322
Number of options, Balance	864,819	719,527
Number of Options, Granted	341,871	187,186
Number of Options, Exercised	(5,199)	(6,914)
Number of Options, Canceled/forfeited	(17,746)	(34,980)
Number of options, Balance	1,183,745	864,819	719,527
Weighted average exercise price, balance	$ 1.17	$ 0.99
Number of options, Exercisable at December 31, 2019	565,975
Weighted average exercise price, Granted	$ 1.91	1.85
Weighted average exercise price, Exercised	1.86	0.99
Weighted average exercise price, Canceled/forfeited	1.88	0.99
Weighted average exercise price, balance	1.37	$ 1.17	$ 0.99
Weighted average exercise price, Exercisable at December 31, 2019	$ 1.16
Weighted average remaining contractual life (years), balance	8 years 21 days	8 years 6 months 14 days	9 years 2 months 4 days
Weighted average remaining contractual life (years), Exercisable	7 years 6 months 21 days
Aggregate intrinsic value, Balance	$ 638,000	$ 582,000
Aggregate intrinsic value, Exercisable	$ 424,000

Share- Based Compensation - Sha

Share- Based Compensation - Share-based compensation expense includes share options granted to employees and nonemployees (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 689	$ 86	$ 3,693	$ 222
Research and Development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	(359)	25	2,008	79
General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 1,048	10	$ 1,685	24
Cost of Services for Related-party Revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense		$ 51		$ 119
Predecessor Company
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense					$ 297	$ 269
Predecessor Company | Research and Development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense					105	195
Predecessor Company | General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense					33	16
Predecessor Company | Cost of Services for Related-party Revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense					$ 159	$ 58

Share- Based Compensation - Fai

Share- Based Compensation - Fair value of each option grant (Detail) - Predecessor Company	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Risk-free interest rate, minimum	1.70%	2.60%
Risk-free interest rate, maximum	2.10%	3.00%
Expected dividend rate	0.00%	0.00%
Expected share price volatility, minimum	75.20%	66.50%
Expected share price volatility, maximum	80.50%	68.70%
Minimum
Expected term (in years)	4 years 4 months 24 days	5 years 2 months 12 days
Maximum
Expected term (in years)	6 years	6 years

Share- Based Compensation - S_2

Share- Based Compensation - Summary of Founder Stock activity (Detail) - Predecessor Company - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Number of Shares, Unvested	113,864	455,477
Number of Shares, Unvested	(113,864)	(341,613)
Number of Shares, Unvested		113,864
Weighted Average Grant Date Fair Value, Unvested	$ 0.35	$ 0.35
Weighted Average Grant Date Fair Value, vested	$ 0.35	0.35
Weighted Average Grant Date Fair Value, Unvested		$ 0.35

Income Taxes - Domestic (Irelan

Income Taxes - Domestic (Ireland) and Foreign Components of Pre-Tax Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Loss before income taxes	$ (10,146)	$ (3,036)	$ (26,907)	$ (11,454)
Predecessor Company
Foreign					$ (16,803)	$ (12,576)
Domestic (Ireland)					(2,406)	(1,110)
Loss before income taxes					$ (19,209)	$ (13,686)

Income Taxes - Schedule of Prov

Income Taxes - Schedule of Provision for Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Deferred
Provision for income taxes	$ 35	$ 8	$ 59	$ 25
Predecessor Company
Current
Domestic (Ireland)					$ 0	$ 0
State (U.S.)					1	1
Foreign/federal					33	44
Total current					34	45
Deferred
Domestic (Ireland)					0	0
State (U.S.)					0	0
Foreign/federal					0	0
Total deferred					0	0
Provision for income taxes					$ 34	$ 45

Income Taxes - Additional infor

Income Taxes - Additional information (Detail) - Predecessor Company - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Statutory federal income tax (as a percent)	12.50%	12.50%
Deferred tax assets, increase in valuation allowance	$ 4,500,000	$ 800,000
Recognized interest and penalties expense (benefit) related to unrecognized tax benefits	0	$ 0
UNITED STATES | State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 30,900,000
Operating loss carryforwards, expiration date	Dec. 31, 2038
UNITED STATES | State and Local Jurisdiction | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Research and development credit carryforwards	$ 2,400,000
UNITED STATES | Federal | Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Research and development credit carryforwards	$ 1,500,000
Research and development credit carryforwards, expiration date	Dec. 31, 2038
IRELAND
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 4,000,000

Income Taxes - Schedule of Stat

Income Taxes - Schedule of Statutory and Effective Income Tax Rate Reconciliation (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Provision for income taxes	$ 35	$ 8	$ 59	$ 25
Predecessor Company
At statutory rate					$ (2,401)	$ (1,711)
Foreign income tax at different rates					378	1,404
U.S. R&D credits					(861)	(499)
Change in valuation allowance					3,733	732
Share-based compensation					60	57
Prior period true ups					(950)	(38)
Other					75	100
Provision for income taxes					$ 34	$ 45

Income Taxes - Significant Comp

Income Taxes - Significant Components of Deferred Tax Assets (Detail) - Predecessor Company - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating loss carryforwards	$ 3,259	$ 363
Research & other credits	3,260	1,701
Other	333	208
Total gross DTA	6,852	2,272
Less: Val. Allowance	(6,686)	(2,181)
Total deferred tax assets	166	91
Deferred tax liabilities:
Fixed assets	166	(91)
Total gross DTL	166	(91)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Schedule of Unre

Income Taxes - Schedule of Unrecognized Tax Benefits (Detail) - Predecessor Company - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Beginning balance	$ 418	$ 247
Gross increase-tax positions in prior periods	9	11
Gross decreases-tax positions in prior periods	(7)
Gross increases-tax positions in prior periods	272	160
Ending balance	$ 692	$ 418

Commitments and Contingencies -

Commitments and Contingencies - Summary of Company's Commitments and Contractual Obligations (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Term loan, 2020	$ 3,743
Term loan, 2021	3,007
Operating lease obligations, Total	380
Operating lease obligations, 2020	34
Operating lease obligations, 2021 - 2022	284
Operating lease obligations, 2023 - 2024	62
Operating lease obligations,Thereafter	0
Manufacturing and service contracts, Total	7,622
Manufacturing and service contracts, 2020	6,238
Manufacturing and service contracts, 2021 - 2022	1,384
Manufacturing and service contracts, 2023 - 2024	0
Manufacturing and service contracts, Thereafter	0
Term loan, Total	6,856
Term loan, 2020	106
Term loan, 2021 - 2022	6,750
Term loan, 2023 - 2024,	0
Term loan, Thereafter	0
Contractual Obligation, Total	14,858
Contractual Obligation, 2020	6,378
Contractual Obligation, 2021 - 2022	8,418
Contractual Obligation, 2023 - 2024	62
Contractual Obligation, Thereafter	$ 0
Predecessor Company
Operating lease obligations, 2020		$ 544
Term loan, 2020		401
Manufacturing and service contracts, 2020		926
Operating lease obligations, 2021		560
Term loan, 2021		3,743
Manufacturing and service contracts, 2021		5,805
Operating lease obligations, 2022		577
Term loan, 2022		3,007
Operating lease obligations, 2023		247
Operating lease obligations, Total		1,928
Manufacturing and service contracts, Total		6,731
Term loan, Total		$ 7,151

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Company's Commitments and Contractual Obligations (Parenthetical) (Detail) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended	12 Months Ended
	Nov. 30, 2015	Sep. 30, 2020	Dec. 31, 2019
Purchase obligations		$ 7,622
Office and Laboratory Space | Burlingame, California
Operating sub-lease expiration year		2023
Master Service Agreement
Initial term of agreement	3 years
Renewal periods of agreement	1 year
Purchase obligations	$ 7,500
Master Service Agreement | Second Drug Product Manufacturer
Purchase obligations	$ 100
Predecessor Company
Purchase obligations			$ 6,731
Predecessor Company | Office and Laboratory Space | Burlingame, California
Operating sub-lease expiration year			2023
Predecessor Company | Master Service Agreement
Initial term of agreement	3 years

Commitments and Contingencies_3

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Nov. 30, 2015	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 12, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies [Line Items]
Rent expense		$ 0.1	$ 0.2	$ 0.5	$ 0.6
Master Service Agreement
Commitments and Contingencies [Line Items]
Initial term of agreement	3 years
Predecessor Company
Commitments and Contingencies [Line Items]
Rent expense						$ 0.8	$ 1
Predecessor Company | Master Service Agreement
Commitments and Contingencies [Line Items]
Initial term of agreement	3 years
Office Space
Commitments and Contingencies [Line Items]
Lessee, operating lease, term of contract									5 years 4 months
Lessee, operating lease commencing end date									May 31, 2023
Office Space | Predecessor Company
Commitments and Contingencies [Line Items]
Lessee, operating lease, term of contract								5 years 4 months		4 years	3 years 2 months
Lessee, operating lease commencing end date								May 31, 2023		May 31, 2020	May 31, 2018
Sublease agreement termination period										2018-05

License Agreement - Additional

License Agreement - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Exclusive Equity Agreement | Stanford Junior University
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Nonrefundable license royalty and patent expenses	$ 0.1
Clinical and regulatory milestones payments	$ 5
Agreement expiry description	licensed patents expires and ten years after the first commercial sale of the licensed product in such country
Termination of agreement written notice period	60 days
Notice period to remedy the breach of agreement	60 days
Exclusive Equity Agreement | Stanford Junior University | Predecessor Company
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Nonrefundable license royalty and patent expenses		$ 0.1
Clinical and regulatory milestones payments		$ 5
Agreement expiry description		licensed patents expires and ten years after the first commercial sale of the licensed product in such country
Termination of agreement written notice period		60 days
Notice period to remedy the breach of agreement		60 days
Commercial License Agreement | Selexis SA
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Clinical and regulatory milestones payments	$ 1.2
Agreement expiry description	shall terminate and become fully paid-up upon the passing of ten years after the first commercial sale of the product in such country, or the Company's exercise of the royalty buyout option exercisable at any time prior to the first commercial sale of a licensed product.
Termination of agreement written notice period	60 days
Notice period to remedy the breach of agreement	60 days
Commercial License Agreement | Selexis SA | Predecessor Company
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Clinical and regulatory milestones payments		$ 1.2
Agreement expiry description		shall terminate and become fully paid-up upon the passing of ten years after the first commercial sale of the product in such country, or the Company's exercise of the royalty buyout option exercisable at any time prior to the first commercial sale of a licensed product.
Termination of agreement written notice period		60 days
Notice period to remedy the breach of agreement		60 days
Commercial Antibody Agreement | Crystal Bioscience Inc
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Clinical and regulatory milestones payments	$ 11.1
Agreement expiry description	licensed patents expires and ten years after the first commercial sale of the product in such country
Termination of agreement written notice period	60 days
Notice period to remedy the breach of agreement	60 days
Commercial Antibody Agreement | Crystal Bioscience Inc | Predecessor Company
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Clinical and regulatory milestones payments		$ 11.1
Agreement expiry description		licensed patents expires and ten years after the first commercial sale of the product in such country
Termination of agreement written notice period		60 days
Notice period to remedy the breach of agreement		60 days

Related-Party Transactions - Ad

Related-Party Transactions - Additional Information (Detail)	Jul. 01, 2020	Jun. 30, 2018	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)Investors	Dec. 31, 2019USD ($)Investors	Dec. 31, 2018USD ($)
Related Party Transaction [Line Items]
Research and development costs			$ 5,328,000	$ 2,210,000	$ 16,819,000	$ 9,571,000
Predecessor Company
Related Party Transaction [Line Items]
Research and development costs							$ 16,306,000	$ 11,270,000
Tollnine
Related Party Transaction [Line Items]
Outstanding related-party receivables			500,000		500,000		500,000
Tollnine | Predecessor Company
Related Party Transaction [Line Items]
Outstanding related-party receivables							$ 500,000	900,000
Research and Development Services Agreement | Tollnine
Related Party Transaction [Line Items]
Number of company's investors who are investors in related party as well | Investors						2
Related-party revenues			$ 0	$ 1,300	$ 1,200	$ 3,600
Initial term of agreement with related party		3 years
Agreement automatically renewal additional term unless terminated		0.00%	0.00%	0.00%	0.00%	0.00%
Markup cost in percentage		10.00%
Research and Development Services Agreement | Tollnine | Predecessor Company
Related Party Transaction [Line Items]
Number of company's investors who are investors in related party as well | Investors							2
Related-party revenues							$ 4,800,000	$ 2,100,000
Research and Development Services Agreement | Tallac Therapeutics
Related Party Transaction [Line Items]
Initial term of agreement with related party	4 years
Agreement automatically renewal additional term unless terminated	0.00%		0.00%		0.00%
Markup cost in percentage	10.00%
Research and development costs			$ 400,000

Net Loss Per Share Attributab_3

Net Loss Per Share Attributable to Common Stockholders - Computation of Basic and Diluted Net Loss per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended		12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net loss	$ (10,181)	$ (11,331)	$ (5,454)	$ (3,044)	$ (4,197)	$ (4,238)	$ (26,966)	$ (11,479)
Less: cumulative dividends allocated to preferred shareholders	(578)			(1,071)			(5,202)	(2,957)
Net loss attributable to common stockholders	$ (10,759)			$ (4,115)			$ (32,168)	$ (14,436)
Denominator:
Weighted-average ordinary shares outstanding	29,664,122			3,100,544			12,052,876	3,061,082
Net loss per share attributable to common stockholders, basic and diluted	$ (0.36)			$ (1.33)			$ (2.67)	$ (4.72)
Predecessor Company
Numerator:
Net loss									$ (19,243)	$ (13,731)
Less: cumulative dividends allocated to preferred shareholders									(4,028)	(3,671)
Net loss attributable to common stockholders									$ (23,271)	$ (17,402)
Denominator:
Weighted-average ordinary shares outstanding									3,076,461	2,750,838
Net loss per share attributable to common stockholders, basic and diluted									$ (7.56)	$ (6.33)

Net Loss Per Share Attributab_4

Net Loss Per Share Attributable to Common Stockholders - Summary of Outstanding Potentially Dilutive Securities Were Excluded from Computation of Diluted Net Loss Per Share (Detail) - shares	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities excluded from computation of earnings per share	4,751,842	11,573,568	4,751,842	11,573,568
Convertible Preferred Stock
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities excluded from computation of earnings per share		10,313,808		10,313,808
Predecessor Company
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities excluded from computation of earnings per share					11,592,869,000	10,391,812,000
Predecessor Company | Series A Convertible Preferred Stock
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities excluded from computation of earnings per share					9,297,081,000	9,297,081,000
Predecessor Company | Series B Convertible Preferred Stock
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities excluded from computation of earnings per share					1,016,727,000
Warrants to Purchase Convertible Preferred Stock | Predecessor Company
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities excluded from computation of earnings per share					61,292,000
Common Stock Subject to Repurchase
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities excluded from computation of earnings per share	253	53,070	253	53,070
Common Stock Subject to Repurchase | Predecessor Company
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities excluded from computation of earnings per share					34,024,000	229,912,000
Options Issued and Outstanding
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities excluded from computation of earnings per share	4,751,589	1,206,690	4,751,589	1,206,690
Options Issued and Outstanding | Predecessor Company
Potentially Dilutive Securities Outstanding [Line Items]
Antidilutive securities excluded from computation of earnings per share					1,183,745,000	864,819,000

Net Loss Per Share Attributab_5

Net Loss Per Share Attributable to Ordinary Shareholders and Unaudited ProForma Net Loss Per Share - Computation of Unaudited ProForma Basic and Diluted Net Loss per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended		12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Computation of Earnings Per Share [Line Items]
Net loss	$ (10,181)	$ (11,331)	$ (5,454)	$ (3,044)	$ (4,197)	$ (4,238)	$ (26,966)	$ (11,479)
Weighted-average ordinary shares used in computing net loss per share attributable to ordinary shareholders, basic and diluted	29,664,122			3,100,544			12,052,876	3,061,082
Predecessor Company
Computation of Earnings Per Share [Line Items]
Net loss									$ (19,243)	$ (13,731)
Weighted-average ordinary shares used in computing net loss per share attributable to ordinary shareholders, basic and diluted									3,076,461	2,750,838
Pro forma adjustment to reflect assumed conversion of preferred shares and accrued dividends allocable to ordinary shareholders									11,253,839
Weighted-average ordinary shares used to compute pro forma net loss per share, basic and diluted									14,330,300
Pro forma net loss per share, basic and diluted									$ (1.34)

Organization - Additional Infor

Organization - Additional Information (Detail) - USD ($) $ in Thousands	Jul. 21, 2020	Jul. 31, 2020	Sep. 30, 2020	Sep. 30, 2020	Apr. 01, 2020	Dec. 31, 2019
Organization [Line Items]
Underwriting discounts and commissions paid				$ 3,183
Common stock, shares authorized	1,000,000,000		1,000,000,000	1,000,000,000	151	1,519,618,271
Convertible preferred stock, shares authorized						11,567,003
Cash and cash equivalents			$ 259,484	$ 259,484		$ 9,017
Common Stock
Organization [Line Items]
Shares issued			9,775,000
Undesignated Preferred Stock
Organization [Line Items]
Convertible preferred stock, shares authorized	100,000,000
Initial Public Offering | Common Stock
Organization [Line Items]
Shares issued	9,775,000	9,775,000
Net proceeds from initial public offering	$ 169,500	$ 169,500
Underwriting discounts and commissions paid	13,000	13,000
Payment for offering related expense	$ 3,200	$ 3,200
Convertible shares converted into common stock	23,934,533	23,934,533

Significant Accounting Polici_2

Significant Accounting Policies - Additional Information (Detail)	Jul. 08, 2020	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Jul. 31, 2020shares	Jul. 21, 2020shares
Significant Accounting Policies [Line Items]
Reverse stock split, description				On July 8, 2020, the Company's board of directors approved an amendment to the Company's certificate of incorporation to effect a 1-for-6.5806 reverse split of its common stock and convertible preferred stock.
Reverse stock split, conversion ratio	0.151961827
Impairment charges | $		$ 0	$ 0	$ 0	$ 0
ASU 2016-13
Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]		true		true
Change in Accounting Principle, Accounting Standards Update, Adoption Date		Jan. 1, 2020		Jan. 1, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]		true		true
ASU 2018-13
Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]		true		true
Change in Accounting Principle, Accounting Standards Update, Adoption Date		Jan. 1, 2020		Jan. 1, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]		true		true
Initial Public Offering | Common Stock
Significant Accounting Policies [Line Items]
Convertible shares converted into common stock | shares						23,934,533	23,934,533