CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 32,641	$ 115,069
Marketable securities	143,441	60,576
Prepaid expenses and other current assets	3,157	2,296
Total current assets	179,239	177,941
Property and equipment, net	4,311	3,190
Operating lease right-of-use asset	4,702
Restricted cash	205	205
Other long-term assets	85
Total assets	188,542	181,336
Current liabilities:
Accounts payable	3,032	3,303
Accrued expenses	8,141	7,157
Deferred rent		16
Operating lease liability	1,082
Loan payable		424
Deferred revenue	20,252	20,209
Other current liabilities	15	14
Total current liabilities	32,522	31,123
Long-term portion of deferred rent		871
Long-term portion of operating lease liability	4,484
Other long-term liabilities	13	24
Long-term portion of deferred revenue	29,733	42,695
Total liabilities	66,752	74,713
Commitments and contingencies (Note 8)
Stockholders' equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized at September 30, 2019 and December 31, 2018; no shares issued and outstanding at September 30, 2019 and December 31, 2018
Common stock, $0.001 par value; 150,000,000 shares authorized and 29,678,422 shares issued and outstanding as of September 30, 2019; 150,000,000 shares authorized and 26,217,701 shares issued and outstanding as of December 31, 2018	30	26
Additional paid-in capital	268,009	213,453
Accumulated other comprehensive income (loss)	26	(8)
Accumulated deficit	(146,275)	(106,848)
Total stockholders' equity	121,790	106,623
Total liabilities and stockholders' equity	$ 188,542	$ 181,336