Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 78,977	$ 114,592
Marketable securities	10,089
Prepaid expenses and other current assets	3,144	2,711
Total current assets	92,210	117,303
Property and equipment, net	1,149	1,210
Deferred offering costs	61
Restricted cash	425	425
Operating lease, right-of-use assets	11,372
Total assets	105,217	118,938
Current liabilities:
Accounts payable	4,983	5,723
Accrued expenses and other current liabilities	10,389	8,937
Current portion of lease liabilities - operating lease	2,382
Total current liabilities	17,754	14,660
Long-term debt, net of current portion and discount	29,603
Operating lease liabilities, net of current portion	9,481
Deferred rent, net of current portion		118
Other long-term liabilities	227	2
Total liabilities	57,065	14,780
Stockholders' equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued or outstanding at September 30, 2019 and December 31, 2018
Common stock, $0.0001 par value; 200,000,000 shares authorized at September 30, 2019 and December 31, 2018, respectively; 25,866,632 and 25,803,475 shares issued at September 30, 2019 and December 31, 2018, respectively; 25,866,547 and 25,803,135 shares outstanding at September 30, 2019 and December 31, 2018, respectively	3	3
Additional paid-in capital	343,327	337,992
Accumulated other comprehensive gain	1
Accumulated deficit	(295,179)	(233,837)
Total stockholders' equity	48,152	104,158
Total liabilities and stockholders' equity	$ 105,217	$ 118,938