Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2022

The following table summarizes common stock share activity for the three months ended March 31, 2022 and 2021 (dollars in thousands):

	Three Months Ended March 31, 2022
	Shares of Common Stock		Common Stock		Additional Paid-in Capital			Accumulated Deficit			Total Stockholders’ Equity
Balance, December 31, 2021		28,705,334	$	32	$	400,705		$	(359,479	)	$	41,258
Net loss		—		—		—			(5,451	)		(5,451	)
Stock-based compensation expense		—		—		922			—			922
Common stock issued, net of expenses		487,610		—		2,135			—			2,135
Common stock issued through employee stock purchase plan		3,120		—		10			—			10
Common stock issued for vested restricted stock units		25,094		—		(18	)		—			(18	)
Vested Loan Agreement warrants		—		—		71						71
Balance, March 31, 2022		29,221,158	$	32	$	403,825		$	(364,930	)	$	38,927

	Three Months Ended March 31, 2021
	Shares of Common Stock		Common Stock		Additional Paid-in Capital			Accumulated Deficit			Total Stockholders’ Equity
Balance, December 31, 2020		19,663,698	$	20	$	349,351		$	(326,613	)	$	22,758
Net loss		—		—		—			(4,676	)		(4,676	)
Stock-based compensation expense		—		—		398			—			398
Common stock issued for conversion of April 2020 Notes		959,080		1		7,452			—			7,453
Common stock issued through employee stock purchase plan		2,184		—		6			—			6
Common stock issued for vested restricted stock units		675		—		(15	)		—			(15	)
Balance, March 31, 2021		20,625,637	$	21	$	357,192		$	(331,289	)	$	25,924

The Company had reserved shares of common stock for future issuance as follows:

	March 31, 2022		December 31, 2021
Outstanding stock options		2,050,094		1,542,126
Outstanding restricted stock units		981,841		133,834
Warrants to purchase common stock associated with March 2018 Public Offering – Series 2		798,810		798,810
Warrants to purchase common stock associated with December 2020 Public Offering - Series 2		6,800,000		6,800,000
Prefunded warrants to purchase common stock associated with December 2020 Public Offering		3,200,000		3,200,000
Warrants to purchase common stock associated with Loan Agreement		198,819		170,410
Warrant to purchase common stock associated with Danforth		50,000		50,000
For possible future issuance for the conversion of the March 2019 Notes		1,138,200		1,138,200
For possible future issuance under 2014 Plan (Note 9)		150,114		295,220
For possible future issuance under Employee Stock Purchase Plan		3,714		3,893
For possible future issuance under 2015 Plan (Note 9)		147,250		235,000
Total common shares reserved for future issuance		15,518,842		14,367,493