STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net loss	$ (116,112)	$ (75,617)	$ (68,548)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	215	158	64
Accretion and amortization on investments, net	1,424	818	(1,534)
Amortization of debt issuance costs/debt discount	893	179
Gain on sales of available for sale securities		(19)
Net gain on exchange and sales of equity investment	(1,233)	(148)
Change in fair value of equity investment, including foreign currency translation		(163)	196
Stock-based compensation for services by non-employees	91	85	68
Stock-based compensation for employees and directors	8,080	6,895	6,079
Amortization related to 401(k) contributions			9
Amortization of right-of-use assets	568	777	712
Changes in assets and liabilities:
Interest and other receivables	(1,041)	80	366
Prepaid and other current assets	1,317	(1,286)	121
Deposit and other assets	(3,807)	(206)	(964)
Accounts payable	(232)	5,731	199
Accrued compensation and benefits	(119)	3,388	2,188
Amount due to Janssen Biotech, Inc.		(14,269)	11,659
Accrued liabilities	14,909	7,397	6,211
Operating lease liabilities	(509)	(452)	(655)
Net cash used in operating activities	(95,556)	(66,652)	(43,829)
Cash flows from investing activities:
Purchases of property and equipment	(207)	(401)	(413)
Purchases of marketable securities	(177,434)	(313,201)	(153,467)
Proceeds from sales of securities available for sale		7,681
Proceeds from maturities of marketable securities	247,994	200,262	181,280
Proceeds from sales of equity investment	1,594	339
Net cash provided by (used in) investing activities	71,947	(105,320)	27,400
Cash flows from financing activities:
Proceeds from issuances of common stock from equity plans	797	208	204
Proceeds from issuance of common stock and warrants in public offering, net of paid issuance costs		140,184
Proceeds from issuances of common stock from at market offerings, net of paid issuance costs	20,385	4,075	19,295
Proceeds from exercise of warrants	2,479	16
Proceeds from debt financing, net of paid debt issuance costs and debt discounts	24,895	23,863
Net cash provided by financing activities	48,556	168,346	19,499
Net increase (decrease) in cash, cash equivalents and restricted cash	24,947	(3,626)	3,070
Cash, cash equivalents and restricted cash at the beginning of the period	10,288	13,914	10,844
Cash, cash equivalents and restricted cash at the end of the period	$ 35,235	$ 10,288	$ 13,914