Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (18,422)	$ (24,436)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	384	403
Stock-based compensation	1,709	2,101
Amortization of operating lease assets	164	94
Purchase net premium on marketable securities		(33)
Net amortization of premium (accretion of discount) on marketable securities	(107)	15
Other	2	2
Changes in operating assets and liabilities:
Accounts payable	1,384	(338)
Prepaid expenses and other assets	622	150
Development receivables	45	(197)
Operating lease liabilities	(198)	(119)
Deferred revenue	(53)	(767)
Accrued and other liabilities	(3,164)	(3,138)
Net cash used in operating activities	(17,634)	(26,263)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of property and equipment		(37)
Purchases of marketable securities		(3,500)
Proceeds from maturities and sales of marketable securities	17,750	29,296
Net cash provided by investing activities	17,750	25,759
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from employee stock plan purchases and stock option exercises	18	184
Principal payments on finance lease obligation	(8)	(172)
Net cash provided by financing activities	10	12
Effect of exchange rate on cash, cash equivalents, and restricted cash	11	(23)
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	137	(515)
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH
Beginning of period	36,416	16,980
End of period	$ 36,553	$ 16,465