Debt and Warrants (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2017

Dec. 31, 2016

Debt and Warrants

Schedule of net long-term debt obligation

	March 31,			December 31,
	2017			2016
Debt and unpaid accrued end-of-term payment	$	3,452,874		$	3,894,320
Unamortized note discount	(30,816		)	(42,493		)
Unamortized debt issuance costs	(95,340		)	(114,626		)
Net debt obligation	$	3,326,718		$	3,737,201
Current portion of long-term debt	$	1,994,015		$	1,919,675
Long-term debt, net of discount	1,332,703			1,817,526
Total	$	3,326,718		$	3,737,201

	December 31, 2016			December 31, 2015
Debt and unpaid accrued end-of-term payment	$	3,894,320		$	6,115,797
Unamortized note discount		(42,493	)		(106,635	)
Unamortized debt issuance costs		(114,626	)		(206,235	)
Net debt obligation	$	3,737,201		$	5,802,927
Current portion of long-term debt	$	1,919,675		$	1,707,899
Long-term debt, net of discount		1,817,526		$	4,095,028
Total	$	3,737,201		$	5,802,927

Schedule of future principal payments under the long-term debt

Years ending December 31	Amount
2017 - April through December	$	1,541,946
2018	1,479,246
Total future principal payments	3,021,192
2018 end-of-term payment	560,000
	3,581,192
Less: unaccreted end-of-term payment at March 31, 2017	(128,318		)
Debt and unpaid accrued end-of-term payment	$	3,452,874

Years ending December 31	Amount
2017	$	2,032,048
2018		1,479,246
Total future principal payments		3,511,294
2018 end-of-term payment		560,000
		4,071,294
Less: unaccreted end-of-term payment at December 31, 2016		(176,974	)
Debt and unpaid accrued end-of-term payment	$	3,894,320

Schedule of interest expense on long-term debt

	Three months ended
	March 31,
	2017		2016
Nominal Interest	$	78,861	$	148,626
Amortization of debt issuance costs	11,678		18,411
Accretion of end-of-term payment	48,655		76,696
Debt issuance costs	36,439		36,016
	$	175,633	$	279,749

	December 31, 2016		December 31, 2015
Nominal Interest	$	457,448	$	224,400
Amortization of debt discount		64,142		27,798
Accretion of end-of-term payment		267,230		115,797
Debt issuance costs		178,713		43,789
	$	967,533	$	411,784

Summary of warrant activity

	Three Months Ended	Year Ended
	March 31,	December 31,
	2017	2016
Beginning balance	5,968,876	748,872
Warrants granted	370,916	5,253,337
Warrants cancelled	—	(33,333	)
Ending balance	6,339,792	5,968,876

	December 31, 2016			December 31, 2015
Beginning balance at January 1		748,872			494,267
Warrants granted		5,253,337			254,605
Warrants cancelled		(33,333	)		—
Ending balance at December 31		5,968,876			748,872