CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 40,839	$ 38,220
Short-term investments	147,128	176,517
Prepaid expenses and other current assets	2,535	6,948
Total current assets	190,502	221,685
Property and equipment, net	40,984	35,637
Deferred offering costs	266
Restricted cash	1,274	1,772
Total assets	233,026	259,094
Current liabilities:
Accounts payable	11,794	15,732
Accrued expenses and other liabilities	3,792	5,040
Deferred rent	1,156	977
Deferred revenue	905	770
Total current liabilities	17,647	22,519
Non-current liabilities:
Deferred rent, net of current portion	10,592	9,470
Deferred revenue, net of current portion	30,523	30,750
Total liabilities	58,762	62,739
Commitments and contingencies (Note 7)
Stockholders’ equity:
Preferred stock, $0.0001 par value, 10,000,000 shares authorized as of March 31, 2019 and December 31, 2018; no shares issued and outstanding at March 31, 2019 and December 31, 2018
Common stock, $0.0001 par value; 200,000,000 shares authorized as of March 31, 2019 and December 31, 2018; 37,557,002 and 37,509,815 shares issued as of March 31, 2019 and December 31, 2018, respectively; and 37,437,297 and 37,358,526 shares outstanding as of March 31, 2019 and December 31, 2018, respectively	3	3
Additional paid-in capital	293,865	292,187
Accumulated other comprehensive gain (loss)	6	(77)
Accumulated deficit	(119,610)	(95,758)
Total stockholders’ equity	174,264	196,355
Total liabilities and stockholders' equity	$ 233,026	$ 259,094