Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 59,427	$ 39,537
Short-term marketable securities	252,042	276,043
Prepaid expenses and other current assets	4,627	4,165
Total current assets	316,096	319,745
Property and equipment, net	9,363	9,687
Operating lease right-of-use asset	6,624	0
Restricted cash	567	567
Long-term marketable securities	29,645	52,257
Other long-term assets	480	480
Total assets	362,775	382,736
Current liabilities:
Accounts payable	1,623	1,850
Deferred rent, current portion	0	1,181
Operating lease liability, current portion	1,829	0
Accrued research and development liabilities	10,365	5,791
Accrued other liabilities	956	602
Accrued compensation	3,248	6,715
Total current liabilities	18,021	16,139
Long-term deferred rent	0	7,619
Long-term operating lease liability	13,306	0
Commitments and contingencies (Note 7)
Stockholders' equity
Common stock, $0.0001 par value, 500,000,000 shares authorized at March 31, 2020 and December 31, 2019; 33,026,825 and 32,950,836 shares issued and outstanding at March 31, 2020 and December 31, 2019, respectively	3	3
Additional paid-in capital	549,622	544,709
Accumulated other comprehensive income	65	9
Accumulated deficit	(218,242)	(185,743)
Total stockholders' equity	331,448	358,978
Total liabilities and stockholders’ equity	$ 362,775	$ 382,736