Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 42,142	$ 31,530
Marketable securities, current	137,459	137,522
Prepaid expenses and other current assets	2,865	2,738
Total current assets	182,466	171,790
Property and equipment, net	12,527	10,283
Deposits and other non-current assets	1,271	1,304
Marketable securities, non-current	800	1,100
Total assets	197,064	184,477
Current liabilities:
Accounts payable	1,422	1,020
Accrued expenses	8,355	11,497
Deferred revenue, current portion	20,250	3,380
Total current liabilities	30,027	15,897
Deferred rent	5,642	5,337
Deferred revenue, net of current portion	94,804	28,180
Other non-current liabilities	1,003	1,012
Total liabilities	131,476	50,426
Commitments and contingencies (see note 6)
Stockholders’ equity:
Preferred stock $0.001 par value: 5,000,000 shares authorized at September 30, 2018 and December 31, 2017; no shares issued and outstanding at September 30, 2018 and December 31, 2017
Common stock, $0.001 par value: 120,000,000 shares authorized at September 30, 2018 and December 31, 2017; 32,309,700 and 31,572,044 shares issued and outstanding at September 30, 2018 and December 31, 2017, respectively	32	32
Additional paid-in capital	312,250	295,019
Accumulated other comprehensive loss	(174)	(287)
Accumulated deficit	(246,520)	(160,713)
Total stockholders’ equity	65,588	134,051
Total liabilities and stockholders’ equity	$ 197,064	$ 184,477