Warrants (Tables)

12 Months Ended

Dec. 31, 2019

Summary of Common Stock Warrants Outstanding

The following common stock warrants were outstanding at December 31, 2019:

	Number of Common Stock Warrants		Per Share Exercise Price		Issuance Date	Expiration Date
Replacement warrants		155	$	483.00	March 3, 2012	March 3, 2022
Issued with redeemable preferred stock*		62		80.10	August 16, 2017	August 16, 2022
Issued with common units in Unit Offering		2,505,250		2.75	October 2, 2018	October 2, 2023
Underwriter warrant issued with public offering		196,650		6.25	October 2, 2018	September 28, 2021
Issued with common units in the Second Registered Direct Offering		4,629,630		5.40	October 10, 2018	October 10, 2023
Issued with common units in the Third Registered Direct Offering		3,052,959		3.21	March 12, 2019	March 12, 2024
Total		10,384,706
*Liability classified warrants

The following common stock warrants were outstanding at December 31, 2018:

	Number of Common Stock Warrants		Per Share Exercise Price		Issuance Date	Expiration Date
Replacement warrants		155	$	483.00	March 3, 2012	March 3, 2022
Issued with redeemable preferred stock*		1,612		80.10	August 16, 2017	August 16, 2022
Issued with common units in Unit Offering		2,516,250		4.18	October 2, 2018	October 2, 2023
Underwriter warrant issued with public offering		196,650		6.25	October 2, 2018	September 28, 2021
Issued with common units in the Second Registered Direct Offering		4,629,630		5.40	October 10, 2018	October 10, 2023
Total		7,344,297
*Liability classified warrants

Summary of Key Assumptions Used in Calculating Marketability Discount

This amount is considered a marketability discount calculated based on an analysis of the leak out provision provided for in the exchange agreements. The key assumptions used in calculating the marketability discount were:

Holding period, in years	0.03
Risk free rate	1.77	%
Dividend yield	0	%
Volatility	109.9	%

Summary of Income Statement Effect of Changes in Outstanding Warrants

The following is a summary of the income statement effect of changes in the Company’s outstanding warrants:

	Year Ended December 31,
	2019		2018
Changes in fair value of warrants	$	30,000	$	(9,160	)
Loss on warrants exchanged		—		(2,688,012	)
Transaction costs		—		(181,312	)
Change in fair value of warrant liability, including gain (loss) on exchange	$	30,000	$	(2,878,484	)

Summary of Warrant Activity

A summary of warrant activity during the years ended December 31, 2019 and 2018 is as follows:

	Year Ended December 31,
	2019			2018
Warrants outstanding, January 1		7,344,297			78,336
Issuances		3,052,959			7,342,530
Exercises, conversions, exchanges and repurchases		(12,550	)		(76,569	)
Warrants outstanding, December 31		10,384,706			7,344,297

Summary of Periodic Changes in Fair Value of Warrant Liability

The periodic changes in the fair value of the warrant liability is as follows:

Balance, January 1, 2018	$	3,400,869
Warrants settled upon exchange		(3,345,029	)
Changes in fair value		9,160
Balance, December 31, 2018		65,000
Warrant repurchases		(25,000	)
Changes in fair value		(30,000	)
Balance, December 31, 2019	$	10,000

Summary of Assumptions Used to Estimate Fair Value

The fair value of contingent payments classified as a liability was estimated using the Monte Carlo simulation valuation model with Level 3 inputs. The assumptions used to estimate the fair value of contingent payments that were classified as a liability at December 31, 2019 were as follows:

Expected volatility	95.3	%
Risk-free interest rate	1.6	%
Cost of capital	30.0	%

Monte Carlo Simulation Model [Member]

Summary of Assumptions Used to Estimate Fair Value

The following assumptions were used to estimate the fair value of warrants classified as a liability using the Monte Carlo simulation valuation model with Level 3 inputs at December 31, 2019 and 2018 were as follows:

	As of December 31,
	2019			2018
Expected volatility		89.87	%		93.90	%
Expected term (years)		2.63			3.60
Risk-free interest rate		1.61	%		2.48	%
Expected dividend yield		0.00	%		0.00	%