Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 61,604	$ 26,591
Short-term marketable securities	24,455	88,143
Accounts receivable	586	784
Prepaid expenses and other current assets	3,404	2,025
Total current assets	90,049	117,543
Property and equipment, net	2,525	2,319
Long-term marketable securities		10,482
Other assets	1,804	371
Total assets	94,378	130,715
Current liabilities:
Accounts payable	6,729	3,070
Accrued expenses	10,512	6,944
Deferred rent	48	232
Deferred revenue	14,151	21,635
Total current liabilities	31,440	31,881
Deferred rent, net of current portion	328	67
Deferred revenue, net of current portion	32,756	28,773
Total liabilities	64,524	60,721
Commitments (Note 9)
Stockholders' equity
Preferred stock, $0.0001 par value; 25,000,000 shares authorized; 0 shares issued and outstanding at September 30, 2018 and December 31, 2017, respectively
Common stock, $0.0001 par value; 175,000,000 shares authorized; 23,160,875 and 22,765,017 shares issued and outstanding at September 30, 2018 and December 31, 2017, respectively	3	3
Additional paid-in capital	171,627	168,018
Accumulated other comprehensive loss	(42)	(149)
Accumulated deficit	(141,734)	(97,878)
Total stockholders’ equity	29,854	69,994
Total liabilities and stockholders’ equity	$ 94,378	$ 130,715