Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities
Net loss	$ (22,122)	$ (8,381)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	17
Stock-based compensation	1,204	543
Non-cash interest expense	140	109
Non-cash change in fair value of PIPE Warrant liability	2,396	(2,648)
Amortization of premium and discount on investments		(51)
Changes in operating assets and liabilities:
Trade receivables, net	(1,144)	(1,148)
Partnership receivables	(225)
Prepaid expenses and other current assets	468	559
Operating lease right-of-use asset	113	(1,383)
Other non-current assets	(100)
Accounts payable	583	1,499
Accrued contract research	735	(580)
Other accrued liabilities	260	(860)
Operating lease liability	(38)	438
Deferred revenue	(493)	(493)
Deferred research and development reimbursements	(52)	117
Operating lease liability, non-current	(76)	592
Net cash used in operating activities	(18,334)	(11,687)
Investing activities
Purchases of marketable securities		(7,152)
Proceeds from maturities and sales of marketable securities		15,000
Purchases of property and equipment		(100)
Net cash provided by investing activities		7,748
Financing activities
Proceeds from issuance of common stock, net of issuance costs	54,980
Proceeds from issuance of loan payable	20,000
Proceeds from warrant exercises	3,092
Payment on principal of loan payable (Note 6)		(2,389)
Payment of debt issuance costs	(85)
Net cash provided by (used in) financing activities	77,987	(2,389)
Net increase (decrease) in cash and cash equivalents	59,653	(6,328)
Cash and cash equivalents at beginning of period	61,761	29,785
Cash and cash equivalents at end of period	121,414	23,457
Supplemental cash flow information
Cash paid for interest	$ 362	368
Right-of-use asset obtained in exchange for operating lease liabilities		$ 1,225