Condensed Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities
Net loss	$ (1,982,786)	$ (5,052,039)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	393,775	464,158
Change in fair value of warrant liability	(433,392)	3,072,747
Change in operating assets and liabilities:
Prepaid expenses and other assets	83,682	104,184
Accounts payable and accrued expenses	(879,245)	(275,862)
Net cash used in operating activities	(2,817,966)	(1,686,812)
Financing activities
Proceeds from issuance of common stock, net	544,643	7,334,739
Net cash provided by financing activities	544,643	7,334,739
Net increase (decrease) in cash and cash equivalents	(2,273,323)	5,647,927
Cash and cash equivalents at beginning of period	7,679,267	9,007,071
Cash and cash equivalents at end of period	5,405,944	14,654,998
Non-cash financing activities
Reclassification of warrant liability to equity due to exercise of warrants		$ 1,399,091
Reclassification of warrant liability to equity due to amendment of warrants	$ 3,267,885