CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating activities
Net loss	$ (56,037)	$ (43,047)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,057	111
Stock-based compensation	1,398	1,046
Loss from remeasurement of development derivative liability	7,203	4,162
Non-cash interest expense	173	261
Non-cash research and development expense	23,705	5,735
Other non-cash transactions	0	100
Changes in operating assets and liabilities:
Receivable from sublicense	(18,400)	0
Other receivables	0	1,233
Prepaid expenses and other assets	8,855	(7,107)
Accounts payable	(585)	4,302
Accrued expenses and other current liabilities	1,679	419
Deferred sublicense revenue	9,662	0
Net cash used in operating activities	(21,290)	(32,785)
Investing activities
Purchases of property and equipment	(385)	(1,079)
Acquisition of intellectual property rights	0	(100)
Net cash used in investing activities	(385)	(1,179)
Financing activities
Proceeds from development derivative liability	0	12,649
Proceeds from issuance of common stock in public offering, net	60,351	472
Payments of deferred stock offering costs	(40)	(175)
Proceeds from exercise of stock options	223	18
Issuance of common stock through employee share purchase plan	202	0
Repayments of long-term debt	(2,727)	0
Net cash provided by financing activities	58,009	12,964
Net increase (decrease) in cash and cash equivalents	36,334	(21,000)
Cash and cash equivalents at the beginning of the period	28,122	74,025
Cash and cash equivalents at the end of the period	64,456	53,025
Supplemental disclosure for cash flow
Cash paid for interest	366	496
Supplemental disclosure of non-cash investing and financing activities
Issuance of warrants in conjunction with development derivative liability	0	7,925
Initial recognition of operating lease right-of-use assets and operating lease liabilities	0	564
Purchases of property and equipment by incurring development derivative liability	4,160	0
Purchases of property and equipment included in accounts payable and accrued expenses	$ 44	$ 2,741