Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current Assets
Cash and cash equivalents	$ 44,975	$ 56,992
Prepaid expenses and other current assets	3,493	1,038
Total current assets	48,468	58,030
Restricted cash	2,418	2,396
Property and equipment, net	1,902	32
Operating lease right-of-use assets	9,092
Build-to-suit lease asset		8,651
Intangible asset, net	249	341
Other assets	457	20
Total assets	62,586	69,470
Current liabilities
Accounts payable	2,364	426
Accrued liabilities	1,557	1,365
Operating lease obligation, current portion	2,464
Deferred revenue		146
Total current liabilities	6,385	1,937
Contingent payable	264	264
Operating lease obligation	8,407
Build-to-suit lease obligation		7,324
Total liabilities	15,056	9,525
Commitments and contingencies (Note 6)
Stockholders' equity
Common stock, $0.0001 par value, 100,000,000 shares authorized at September 30, 2019 and December 31, 2018; 11,284,964 and 11,266,151 shares issued and outstanding at September 30, 2019 and December 31, 2018, respectively	1	1
Additional paid-in capital	513,312	510,509
Accumulated deficit	(465,783)	(450,565)
Total stockholders' equity	47,530	59,945
Total liabilities and stockholders’ equity	$ 62,586	$ 69,470