Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (25,101,000)	$ (16,007,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,131,000	996,000
Accretion of premium (discount) on investments	36,000	0
Stock-based compensation	3,130,000	1,251,000
Non-cash interest expense related to sale of future royalties	340,000	466,000
Non-cash revenue related to sale of future royalties	(71,000)	(334,000)
Change in operating assets and liabilities:
Accounts receivable	(10,000)	(366,000)
Prepaid expenses and other assets	(4,498,000)	(2,694,000)
Accounts payable	113,000	2,281,000
Other accrued liabilities	(183,000)	(2,185,000)
Net cash used in operating activities	(25,113,000)	(16,592,000)
Cash flows from investing activities:
Purchase of property and equipment	(1,346,000)	(615,000)
Purchases of investments	(8,522,000)	(19,944,000)
Proceeds from maturities of investments	13,600,000	0
Net cash provided by (used in) investing activities	3,732,000	(20,559,000)
Cash flows from financing activities:
Net proceeds from issuance of common stock through ATM facilities	992,000	65,712,000
Proceeds from issuance of common stock upon exercise of common stock warrants	0	1,649,000
Proceeds from issuance of common stock upon exercise of stock options	48,000	231,000
Net cash provided by financing activities	1,040,000	67,592,000
Net (decrease) increase in cash and cash equivalents	(20,341,000)	30,441,000
Cash and cash equivalents at beginning of the period	143,745,000	126,870,000
Cash and cash equivalents at end of the period	123,404,000	157,311,000
Supplemental disclosure of non-cash financing activity:
Operating lease liabilities arising from obtaining right-of-use assets	125,000	0
Acquisition of property and equipment included in accounts payable and accrued expenses	$ 505,000	$ 303,000