CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 53,774	$ 38,220
Short-term investments	208,614	176,517
Prepaid expenses and other current assets	4,189	6,948
Total current assets	266,577	221,685
Property and equipment, net	42,716	35,637
Restricted cash	1,274	1,772
Total assets	310,567	259,094
Current liabilities:
Accounts payable	2,608	15,732
Accrued expenses and other liabilities	7,644	5,040
Deferred rent	1,313	977
Deferred revenue	809	770
Total current liabilities	12,374	22,519
Non-current liabilities:
Deferred rent, net of current portion	9,544	9,470
Deferred revenue, net of current portion	30,142	30,750
Total liabilities	52,060	62,739
Commitments and contingencies (Note 8)
Stockholders’ equity:
Preferred stock, $0.0001 par value, 10,000,000 shares authorized as of December 31, 2019 and 2018, respectively; no shares issued and outstanding at December 31, 2019 and 2018, respectively
Common stock, $0.0001 par value; 200,000,000 shares authorized as of December 31, 2019 and 2018, respectively; 45,138,408 and 37,509,815 shares issued as of December 31, 2019 and 2018, respectively; and 45,116,742 and 37,358,526 shares outstanding as of December 31, 2019 and 2018, respectively	4	3
Additional paid-in capital	457,994	292,187
Accumulated other comprehensive loss	183	(77)
Accumulated deficit	(199,674)	(95,758)
Total stockholders’ equity	258,507	196,355
Total liabilities and stockholders' equity	$ 310,567	$ 259,094