Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net loss	$ (12,170,220)	$ (9,170,410)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	1,485,705	1,415,301
Stock-based 401K company common match	121,620	0
Depreciation expense	42,306	15,300
Amortization of debt discount	12,365	22,534
Amortization of debt issuance costs	27,102	21,016
Non-cash interest expense	92,549	8,955
Changes in assets and liabilities:
Prepaid expenses and other assets	255,055	151,571
Accounts payable	(943,416)	842,864
Accrued expenses	303,255	(2,381,078)
Net cash used in operating activities	(10,773,679)	(9,073,947)
Cash flows from investing activities:
Purchases of property and equipment	(89,284)	(77,287)
Net cash used in investing activities	(89,284)	(77,287)
Cash flows from financing activities:
Proceeds from exercise of stock options	50,960	546
Proceeds from exercise of warrants	3,745	0
Payments for issuance costs	0	(549,178)
Repayment of debt	0	(547,140)
Net cash provided by (used in) financing activities	54,705	(1,095,772)
Net decrease in cash	(10,808,258)	(10,247,006)
Cash and cash equivalents at beginning of period	106,398,919	130,189,421
Cash and cash equivalents at end of period	95,590,661	119,942,415
Cash paid for:
Interest	343,125	133,047
Supplemental cash flow information:
Accrued capital expenditures included in accrued expenses and accounts payable	$ 0	$ 5,000