Stockholders' Equity and Convertible Preferred Stock (Tables)

3 Months Ended

Mar. 31, 2019

Stockholders' Equity Note [Abstract]

Schedule of warrant activity

A summary of warrant activity for the three months ended March 31, 2019 is presented below:

	Warrants			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (in years)
Outstanding as of December 31, 2018		294,072		$	38.15		1.92
Expired		(8,799	)		—		—
Outstanding as of March 31, 2019		285,273		$	24.63		1.67

Schedule of fair value of options granted

A summary of option activity under the Company’s stock option plan for the three months ended March 31, 2019 is presented below:

	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (in years)			Total Intrinsic Value
Outstanding as of December 31, 2018		124,381		$	209.22		4.8	$	—
Employee options expired		(14,994	)		—		—		—
Outstanding as of March 31, 2019		109,387		$	173.51		5.2	$	—
Options vested and expected to vest		109,387		$	173.51		5.2	$	—
Options vested and exercisable		103,504		$	183.12		5.0	$	—

Schedule of stock-based compensation

Stock-based compensation for the three months ended March 31, 2019 and 2018 was comprised of the following ($ in thousands): 

	For the Three Months Ended March 31,
	2019		2018
Non-employee restricted stock awards	$	—	$	80
Employee stock option awards		6		108
Total compensation expense	$	6	$	188