CONDENSED BALANCE SHEETS - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 33,660,918	$ 31,228,192
Short-term investments	93,901,236	106,979,224
Receivables	5,125	55,074
Prepaid expenses	1,526,171	1,737,308
Other assets	283,426	255,912
Total current assets	129,376,876	140,255,710
Property and equipment, net	2,982,871	3,205,077
Other noncurrent assets	27,067	33,567
Total assets	132,386,814	143,494,354
Current liabilities:
Accounts payable	1,546,612	1,381,545
Accrued wages and benefits	1,143,822	2,705,475
Accrued clinical trial expenses	1,207,887	861,293
Accrued expenses and other liabilities	1,017,072	613,861
Total current liabilities	4,915,393	5,562,174
Other liabilities, net of current portion		2,873
Deferred revenue, net of current portion	769,444	781,944
Total liabilities	5,684,837	6,346,991
Stockholders’ equity:
Common stock: $0.001 par value, 100,000,000 shares authorized; 42,377,522 and 42,470,874 shares issued and outstanding at December 31, 2016 and March 31, 2017	42,471	42,378
Additional paid-in capital	392,092,353	390,768,742
Accumulated other comprehensive (loss) income	(53,877)	(41,196)
Retained deficit	(265,378,970)	(253,622,561)
Total stockholders’ equity	126,701,977	137,147,363
Total liabilities and stockholders’ equity	$ 132,386,814	$ 143,494,354