CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 165,317	$ 171,017
Receivable from collaborative partners	5,000	0
Short-term investments	197,166	203,210
Prepaid expenses and other current assets	3,572	3,506
Total current assets	371,055	377,733
Property and equipment, net	1,610	1,618
Long-term investments	50,215	54,305
Other long-term assets	1,293	1,481
Restricted cash	60	60
Total assets	424,233	435,197
Current liabilities:
Accounts payable	8,571	16,237
Accrued expenses	13,781	11,052
Notes payable, current portion	0	1,375
Other current liabilities	898	871
Total current liabilities	23,250	29,535
Other long-term liabilities	419	654
Stockholders’ equity:
Preferred stock, $0.001 par value, 10,000 shares authorized and no shares, issued or outstanding at March 31, 2020 and December 31, 2019, respectively	0	0
Common stock, $0.001 par value, 500,000 shares authorized, 27,277 shares and 27,255 shares issued and outstanding at March 31, 2020 and December 31, 2019, respectively	27	27
Additional paid in capital	651,680	648,669
Accumulated other comprehensive income	1,145	338
Accumulated deficit	(252,288)	(244,026)
Total stockholders’ equity	400,564	405,008
Total liabilities and stockholders’ equity	$ 424,233	$ 435,197