CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 167,636	$ 53,774
Short-term investments	39,007	208,614
Prepaid expenses and other current assets	3,164	4,189
Total current assets	209,807	266,577
Property and equipment, net	40,771	42,716
Right-of-use assets	6,386
Restricted cash	1,274	1,274
Total assets	258,238	310,567
Current liabilities:
Accounts payable	7,103	2,608
Accrued expenses and other liabilities	9,274	7,644
Operating lease liabilities	2,413
Deferred rent		1,313
Deferred revenue	774	809
Total current liabilities	19,564	12,374
Non-current liabilities:
Operating lease liabilities, net of current portion	14,190
Deferred rent, net of current portion		9,544
Deferred revenue, net of current portion	29,780	30,142
Total liabilities	63,534	52,060
Commitments and contingencies (Note 7)
Stockholders’ equity:
Preferred stock, $0.0001 par value, 10,000,000 shares authorized; no shares issued and outstanding
Common stock, $0.0001 par value; 200,000,000 shares authorized; 45,215,766 and 45,138,408 shares issued as of June 30, 2020 and December 31, 2019, respectively; and 45,210,653 and 45,116,742 shares outstanding as of June 30, 2020 and December 31, 2019, respectively	4	4
Additional paid-in capital	465,034	457,994
Accumulated other comprehensive gain	11	183
Accumulated deficit	(270,345)	(199,674)
Total stockholders’ equity	194,704	258,507
Total liabilities and stockholders' equity	$ 258,238	$ 310,567