Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current Assets
Cash and cash equivalents	$ 55,592	$ 56,992
Prepaid expenses and other current assets	1,891	1,038
Total current assets	57,483	58,030
Restricted cash	2,400	2,396
Property and equipment, net	2,051	32
Operating lease right-of-use assets	9,799
Build-to-suit lease asset		8,651
Intangible asset, net	310	341
Other assets	20	20
Total assets	72,063	69,470
Current liabilities
Accounts payable	1,369	426
Accrued liabilities	2,431	1,365
Operating lease obligation, current portion	2,534
Deferred revenue	1,054	146
Total current liabilities	7,388	1,937
Contingent payable	264	264
Operating lease obligation	9,450
Build-to-suit lease obligation		7,324
Total liabilities	17,102	9,525
Commitments and contingencies (Note 6)
Stockholders' equity
Preferred stock, $0.0001 par value; 5,000,000 shares authorized at March 31, 2019 and December 31, 2018; zero shares issued and outstanding at March 31, 2019 and December 31, 2018
Common stock, $0.0001 par value, 100,000,000 shares authorized at March 31, 2019 and December 31, 2018; 11,276,500 and 11,266,151 shares issued and outstanding at March 31, 2019 and December 31, 2018, respectively	1	1
Additional paid-in capital	511,557	510,509
Accumulated deficit	(456,597)	(450,565)
Total stockholders' equity	54,961	59,945
Total liabilities and stockholders’ equity	$ 72,063	$ 69,470