Consolidated Statements of Cash Flows $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Operating activities
Net loss	$ (70,819)	$ (82,677)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	2,379	2,053
Stock-based compensation expense	7,350	4,224
In-process research and development expense		25,591
Net amortization of premiums and discounts on marketable securities	(68)
Changes in operating assets and liabilities:
Accounts receivable	(2,000)
Unbilled accounts receivable	(531)
Prepaid expenses and other current assets	(697)	(2,459)
Other assets	(519)	(20)
Accounts payable	1,773	803
Accrued expenses and other liabilities	1,976	2,949
Deferred revenue	7,881	10,000
Deferred rent and deferred lease incentive	(380)	53
Net cash used in operating activities	(53,655)	(39,483)
Investing activities
Purchases of marketable securities	(124,270)
Maturities of marketable securities	68,474
Purchases of property and equipment	(1,342)	(853)
Transaction costs associated with asset acquisition		(91)
Net cash used in investing activities	(57,138)	(944)
Financing activities
Proceeds from initial public offering of common stock, net of underwriting discounts and commissions	(193)	64,173
Proceeds from issuance of common stock in connection with private placement, net of issuance costs	64,210
Proceeds from issuance of common stock in connection with at-the-market offering, net of issuance costs	1,429	249
Principal payments on capital lease obligations	(50)	(45)
Net cash provided by financing activities	71,132	64,343
Net (decrease) increase in cash, cash equivalents and restricted cash	(39,661)	23,916
Cash, cash equivalents, and restricted cash, beginning of period	97,805	73,889
Cash, cash equivalents, and restricted cash, end of period	58,144	97,805
Supplemental cash flow information
Cash paid for interest	4	7
Non-cash investing and financing activities:
Acquisition of in process research and development through issuance of stock		25,500
Conversion of convertible preferred stock into common stock		165,136
Property and equipment purchases unpaid at end of period	262	34
Public offering costs unpaid at end of period		301
Cash and cash equivalents	57,052	96,713
Restricted cash	1,092	1,092
At-The-Market Offering
Financing activities
Proceeds from issuance of common stock in connection with at-the-market offering, net of issuance costs	$ 5,736
Series B Convertible Preferred Stock
Financing activities
Payment of stock issuance costs		$ (34)