Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 41,958	$ 56,718
Short-term investment securities	26,848	27,999
Interest receivable	95	108
Prepaid research and development	9,691	8,056
Other current assets	439	437
Total current assets	79,031	93,318
Restricted cash	1,241	587
Leasehold interest, net	2,294	2,429
Equipment, net	251	248
Goodwill	799	799
Total assets	83,616	97,381
Current liabilities:
Accounts payable and accrued expenses	36,377	25,877
Accrued compensation	2,258	1,800
Current portion of deferred revenue	152	152
Notes payable	67	128
Total current liabilities	38,854	27,957
Deferred rent	1,462	1,364
Deferred revenue, net of current portion	914	1,067
Long-term liabilities	18,350	0
Total liabilities	59,580	30,388
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.001 par value per share (10,000,000 shares authorized, none issued and outstanding as of December 31, 2018 and 2017)	0	0
Common stock, $0.001 par value per share (150,000,000 shares authorized, 83,911,855 and 73,181,750 shares issued, 83,870,546 and 73,140,441 shares outstanding at December 31, 2018 and 2017, respectively)	84	73
Additional paid-in capital	552,531	422,017
Treasury stock, at cost, 41,309 shares at December 31, 2018 and 2017	(234)	(234)
Accumulated deficit	(528,345)	(354,863)
Total stockholders' equity	24,036	66,993
Total liabilities and stockholders' equity	$ 83,616	$ 97,381