Condensed Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 10,157	$ 10,635
Investments	21,365	10,060
Prepaid expenses and other current assets	1,012	1,055
Restricted cash	25	25
Total current assets	32,559	21,775
Operating lease, right-of-use asset	6,385
Property and equipment, net	379	7,290
Restricted cash, non-current	568	568
Other assets	302	679
Total assets	40,193	30,312
Current liabilities:
Accrued expenses and other current liabilities	3,262	3,639
Accounts payable	1,719	1,731
Operating lease liabilities	406
Total current liabilities	5,387	5,370
Operating lease liabilities, net of current portion	4,822
Construction financing liability		5,342
Total liabilities	10,209	10,712
Commitments and contingencies (Note 9)
Stockholders’ equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized at June 30, 2019 and December 31, 2018, respectively; no shares issued and outstanding at June 30, 2019 and December 31, 2018
Common stock, $0.001 par value; 150,000,000 shares authorized at June 30, 2019 and December 31, 2018; 26,713,617 and 14,748,475 shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively; 1,096,741 and 0 pre-funded warrants outstanding at June 30, 2019 and December 31, 2018	28	15
Additional paid-in capital	213,083	188,083
Accumulated other comprehensive loss	24	(5)
Accumulated deficit	(183,151)	(168,493)
Total stockholders’ equity	29,984	19,600
Total liabilities and stockholders’ equity	$ 40,193	$ 30,312