Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating activities:
Net loss	$ (45,995)	$ (34,627)
Reconciliation of net loss to net cash used in operating activities:
Stock-based compensation	8,096	5,755
Depreciation and amortization	283	240
Noncash lease expense	115	95
Accretion of purchase discounts and amortization of premiums on investment securities, net	(530)	322
Loss on equity method investment	0	1,010
Noncash license revenues	2,000	0
Increase (decrease) in cash resulting from changes in:
Prepaid expenses and other assets	1,516	2,489
Accounts payable and accrued expenses	(1,345)	1,530
Deferred revenue	(605)	9,869
Operating lease liability	(253)	(226)
Net cash used in operating activities	(40,718)	(13,543)
Investing activities:
Purchases of investment securities	(22,671)	(55,017)
Maturities of investment securities	71,442	11,720
Purchases of property and equipment	(16)	(87)
Net cash provided by (used in) investing activities	48,755	(43,384)
Financing activities:
Proceeds from exercise of stock options	484	1,780
Net cash provided by financing activities	484	1,780
Net change in cash, cash equivalents and restricted cash	8,521	(55,147)
Cash, cash equivalents and restricted cash at beginning of period	33,973	201,195
Cash, cash equivalents and restricted cash at end of period	42,494	146,048
Components of cash, cash equivalents and restricted cash:
Cash and cash equivalents	41,193	145,548
Restricted cash	1,301	500
Cash, cash equivalents and restricted cash at end of period	42,494	146,048
Noncash investing and financing activities:
Stock received under licensing arrangement	2,000	0
Change in unvested stock liability	0	2
Amounts accrued for purchases of property and equipment	$ 33	$ 0