CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 77,042	$ 85,209
Marketable securities	38,634	41,697
Other receivables	8,548	5,330
Tax incentive receivable, current	74	846
Prepaid expenses and other current assets	5,194	6,063
Total current assets	129,492	139,145
Property and equipment, net	1,510	1,669
Tax incentive receivable	311	311
Operating lease right of use assets	6,915	7,114
Other assets	5,212	5,212
Total assets	143,440	153,451
Current liabilities:
Accounts payable	3,825	1,155
Accrued expenses and other current liabilities	12,958	12,241
Operating lease liabilities	980	947
Total current liabilities	17,763	14,343
Non-current operating lease liabilities	6,663	6,891
Other long-term liabilities	168	177
Total liabilities	24,594	21,411
Commitments and contingencies (Note 8)
Stockholders' equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized, 3,218,152 shares issued and outstanding as of March 31, 2021 and 3,218,287 shares issued and outstanding as of December 31, 2020	3	3
Common stock, $0.001 par value; 60,000,000 shares authorized as of March 31, 2021 and December 31, 2020; 29,663,946 shares issued and outstanding as of March 31, 2021 and 29,260,247 shares issued and outstanding as of December 31, 2020	30	29
Additional paid-in capital	415,946	409,722
Accumulated deficit	(297,130)	(277,707)
Accumulated other comprehensive gain (loss)	(3)	(7)
Total stockholders' equity	118,846	132,040
Total liabilities and stockholders' equity	$ 143,440	$ 153,451