Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2020

The following table shows the warrant activity:

	Rollforward of Warrant Activity
	Registered direct warrants, Series A			Registered direct warrants, Series B			Registered direct warrants, placement agent		Private placement warrants		Private placement warrants, placement agent		Total
Balance as of December 31, 2019		3,449,112			3,449,112			172,456		—		—		7,070,680
Issued		—			—			—		6,898,224		344,911		7,243,135
Exercised		(3,449,112	)		(3,449,112	)		—		—		—		(6,898,224	)
Cancelled/Expired		—			—			—		—		—		—
Balance as of June 30, 2020		—			—			172,456		6,898,224		344,911		7,415,591

Schedule of Stock-Based Compensation Expense Recognized

Total stock-based compensation expense was recognized in our condensed consolidated statements of operations and comprehensive loss as follows (in thousands):

	For the Three Months Ended June 30,				For the Six Months Ended June 30,
	2020		2019		2020		2019
Research and development	$	49	$	186	$	203	$	222
General and administrative		148		441		431		616
Total stock-based compensation	$	197	$	627	$	634	$	838