Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities:
Net loss	$ (29,305,801)	$ (20,119,498)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	4,029,326	1,566,562
Warrant remeasurement	0	1,879,823
Depreciation expense	60,331	38,360
Loss on disposal of fixed assets	102,789	0
Amortization of debt discount	60,206	79,400
Amortization of debt issuance costs	63,699	0
Non-cash interest expense	82,357	28,667
Changes in assets and liabilities:
Prepaid expenses and other assets	633,513	78,814
Accounts payable	(399,708)	(126,415)
Accrued expenses	(1,469,109)	1,604,432
Net cash used in operating activities	(26,142,397)	(14,969,855)
Cash flows from investing activities:
Purchases of property and equipment	(339,410)	(799,424)
Net cash used in investing activities	(339,410)	(799,424)
Cash flows from financing activities:
Proceeds from issuance of debt	11,022,286	3,000,000
Proceeds from exercise of stock options	293,988	0
Proceeds from exercise of warrants	13,107	0
Payments for issuance costs	(544,773)	(474,357)
Payments for debt issuance costs	(219,042)	0
Repayment of debt	(1,488,558)	0
Proceeds from issuance of preferred stock, net of issuance costs	0	52,394,571
Net cash provided by financing activities	9,077,008	54,920,214
Net (decrease) increase in cash	(17,404,799)	39,150,935
Cash and cash equivalents at beginning of period	130,189,421	13,728,972
Cash and cash equivalents at end of period	112,784,622	52,879,907
Cash paid for:
Interest	443,464	412,717
Supplemental cash flow information:
Deferred issuance costs included in accrued expenses and accounts payable	0	552,410
Non-cash financing costs	0	175,114
Accrued capital expenditures included in accrued expenses and accounts payable	$ 348,591	$ 576,839