Balance Sheets - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 20,963,541	$ 20,023,337
Marketable securities	17,974,600	22,923,462
Prepaid expenses and other current assets	1,666,898	1,018,967
Total current assets	40,605,039	43,965,766
Deferred offering costs		165,930
Fixed assets, net	170,862	43,262
Total assets	40,775,901	44,174,958
Current liabilities:
Accounts payable	1,618,889	1,000,963
Accrued expenses	1,815,428	2,236,465
Current portion of credit facility	232,639	116,319
Total current liabilities	3,666,956	3,353,747
Credit facility, net of current portion and debt discount	1,107,741	1,220,192
Total liabilities	4,774,697	4,573,939
Commitments and contingencies (Note 11)
Stockholders' equity:
Preferred stock, $0.001 par value, 15,000,000 shares authorized, none issued and outstanding
Common stock, voting, $0.001 par value; 150,000,000 authorized and 19,664,921 and 19,137,639 shares issued and outstanding, respectively	19,665	19,138
Additional paid-in capital	144,036,909	139,241,635
Accumulated other comprehensive loss	(16,385)	(17,831)
Accumulated deficit	(108,038,985)	(99,641,923)
Total stockholders' equity	36,001,204	39,601,019
Total liabilities and stockholders' equity	$ 40,775,901	$ 44,174,958