Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 47,273	$ 24,869
Marketable securities	113,991	166,076
Accrued interest receivable	284	687
Prepaid research and development expenses	3,761	9,910
Other prepaid expenses and current assets	820	1,381
Total current assets	166,129	202,923
Property and equipment, net	1,929	2,409
Operating lease right-of-use asset	268	235
Other assets	160	160
Total assets	168,486	205,727
Current liabilities:
Accounts payable	947	2,503
Accrued research and development expenses	5,729	9,218
Accrued restructuring	93	3,193
Other accrued liabilities	3,693	2,722
Total current liabilities	10,462	17,636
Long-term portion of operating lease liability	1,389	1,743
Total liabilities	11,851	19,379
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.0001 par value: 10,000,000 shares authorized; no shares issued and outstanding
Common stock, $0.0001 par value: 200,000,000 shares authorized; 68,887,092 and 68,882,459 shares issued and outstanding as of September 30, 2020 and December 31, 2019, respectively	7	7
Additional paid-in capital	817,653	812,133
Accumulated other comprehensive income	82	80
Accumulated deficit	(661,107)	(625,872)
Total stockholders' equity	156,635	186,348
Total liabilities and stockholders' equity	$ 168,486	$ 205,727