CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 39,884	$ 71,431
Short-term investments	12,489
Prepaid expenses and other current assets	1,567	1,376
Total current assets	53,940	72,807
Property and equipment, net	151	207
Operating lease right-of-use asset	171
Other assets	70	9
Total assets	54,332	73,023
Current liabilities:
Accounts payable	457	1,134
Accrued expenses	5,939	7,884
Operating lease liability	189
Total current liabilities	6,585	9,018
Other liabilities	12	11
Total liabilities	6,597	9,029
Commitments and contingencies
Stockholders' equity:
Common stock, $0.001 par value, Authorized — 70,000 shares; Issued and outstanding — 28,827 and 27,188 shares at June 30, 2019 and December 31, 2018, respectively	29	27
Additional paid-in capital	734,229	728,342
Accumulated deficit	(686,525)	(664,375)
Accumulated other comprehensive income	2
Total stockholders' equity	47,735	63,994
Total liabilities and stockholders' equity	54,332	73,023
Series A Preferred Stock
Stockholders' equity:
Preferred stock, $0.01 par value, Authorized — 5,000 shares: Series A convertible preferred stock; Designated — 1,500 shares, Issued and outstanding — 1 share