CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 200,362,000	$ 220,383,000
Restricted cash	556,000	560,000
Short-term investments	13,053,000	23,130,000
Other current assets	5,855,000	5,944,000
Total current assets	219,826,000	250,017,000
Operating lease right-of-use assets	6,953,000	6,901,000
Property and equipment, net	7,573,000	8,007,000
Other assets	188,000	377,000
Total assets	234,540,000	265,302,000
Current liabilities:
Accounts payable	2,810,000	3,313,000
Accrued liabilities	12,283,000	16,564,000
Operating lease liabilities, current	2,512,000	2,442,000
Finance lease liabilities, current	45,000	64,000
Deferred revenue from collaborations, current	7,581,000	7,891,000
Total current liabilities	25,231,000	30,274,000
Operating lease liabilities, net of current portion	10,183,000	10,371,000
Finance lease liabilities, net of current portion	130,000	130,000
Other liabilities	267,000	379,000
Deferred revenue from collaborations, net of current portion	3,509,000	4,109,000
Total liabilities	39,320,000	45,263,000
Commitments and contingencies (Note 12)
Stockholders’ equity (deficit):
Common stock, $0.0001 par value; 320,000,000 shares authorized as of March 31, 2021 (unaudited) and December 31, 2020, respectively; 38,147,205 and 38,120,606 shares issued and outstanding as of March 31, 2021 (unaudited) and December 31, 2020, respectively	4,000	4,000
Additional paid-in capital	397,857,000	394,963,000
Accumulated deficit	(202,414,000)	(174,740,000)
Accumulated other comprehensive loss	(227,000)	(188,000)
Total stockholders’ equity	195,220,000	220,039,000
Total liabilities, preferred stock, and stockholders’ equity (deficit)	234,540,000	265,302,000
Preferred Stock
Current liabilities:
Preferred Stock, $0.0001 par value; 10,000,000 shares authorized as of March 31, 2021 and December 31, 2020; no shares issued and outstanding as of March 31, 2021 and December 31, 2020	$ 0	$ 0