Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 79,223	$ 47,968
Short-term investments	86,873	207,714
Restricted cash	194	194
Prepaid expenses and other current assets	5,900	4,677
Total current assets	172,190	260,553
Property and equipment, net	44,129	3,259
Restricted cash, long term	1,200	0
Other assets	260	102
Total assets	217,779	263,914
Current liabilities:
Accounts payable	14,711	2,778
Accrued compensation	5,664	3,745
Accrued research and development expenses	4,006	2,408
Other current liabilities	3,265	744
Total current liabilities	27,646	9,675
Long-term liabilities	12,269	503
Total liabilities	39,915	10,178
Commitments and contingencies (Note 7)
Stockholders’ equity:
Common stock—$0.0001 par value, 500,000 shares authorized as of December 31, 2017 and December 31, 2016; 30,730 and 28,933 shares issued and outstanding as of December 31, 2017 and December 31, 2016, respectively	3	3
Additional paid-in capital	474,662	431,075
Accumulated other comprehensive loss	(151)	(183)
Accumulated deficit	(296,650)	(177,159)
Total stockholders’ equity	177,864	253,736
Total liabilities and stockholders’ equity	$ 217,779	$ 263,914