Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 25,059	$ 37,473
Short-term marketable securities	84,179	84,508
Strategic investment	4,120	5,507
Prepaid expenses and other current assets	1,875	1,999
Total current assets	115,233	129,487
Property and equipment, net	15,067	16,636
Operating lease right of use asset	25,443
Long-term marketable securities		3,025
Restricted cash	1,446	1,446
Other long-term assets	598	627
Total assets	157,787	151,221
Current liabilities:
Accounts payable	4,015	5,185
Accrued compensation	2,222	5,905
Accrued and other current liabilities	7,422	4,995
Contingent consideration liability	910	1,131
Total current liabilities	14,569	17,216
Operating lease liability, net of current portion	37,889
Deferred rent, net of current portion		13,298
Total liabilities	52,458	30,514
Commitments and contingencies (Note 6)
Stockholders’ equity:
Convertible preferred stock, $0.0001 par value; 10,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.0001 par value; 300,000,000 shares authorized as of March 31, 2020 and December 31, 2019; 48,857,504 and 47,227,065 shares issued and outstanding as of March 31, 2020 and December 31, 2019, respectively	5	5
Additional paid-in capital	379,072	366,695
Related party promissory notes for purchase of common stock	(210)	(210)
Employee promissory notes for purchase of common stock	(418)	(418)
Accumulated other comprehensive income	373	90
Accumulated deficit	(273,493)	(245,455)
Total stockholders’ equity	105,329	120,707
Total liabilities and stockholders’ equity	$ 157,787	$ 151,221