Preferred Stock, Common Stock and Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2022

Equity [Abstract]

Summary of Stock Option Activity

A summary of the Company’s stock option activity under the 2013 Plan is as follows:

	Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding at December 31, 2021		417,788		$	21.60		7.85	—
Granted		78,247		$	6.10		9.24
Expired/Forfeited/Exchanged		(4,184	)	$	20.72		7.42
Outstanding at December 31, 2022		491,851		$	19.11		7.22	$	9,440
Vested and expected to vest at December 31, 2022		491,851		$	19.11		7.22	$	9,440
Exercisable at December 31, 2022		327,107		$	20.70		6.70	$	1,180

Summary of Estimated Fair Value of Stock Option Award

The estimated fair value of each stock option award granted was determined on the date of grant using the Black Scholes option-pricing valuation model with the following assumptions for option grants during the years ended December 31, 2022 and 2021:

	Year Ended December 31,
	2022	2021
Risk free interest rate	1.67%-3.55%	0.57% - 1.08%
Expected option term	5.5- 6.0 years	5.5 - 6.0 years
Expected volatility of common stock	97.04%- 113.23%	103.45% - 107.53%
Expected dividend yield	0.0%	0.0%

Summary of Estimated Fair Value of Shares to be Acquired under Employee Stock Purchase Plan

The estimated fair value of the shares to be acquired under the ESPP was determined on the initiation date of each six-month purchase period using the Black-Scholes option-pricing valuation model with the following assumptions for ESPP shares to be purchased during the years ended December 31, 2022 and 2021 as follows:

	Year Ended December 31,
	2022	2021
Risk free interest rate	—	0.13%
Expected term	—	0.5 years
Expected volatility of common stock	—	111.98%
Expected dividend yield	—	0.0%

Summary of Recognized Stock-Based Compensation Expense

The Company recognized stock-based compensation expense to employees and directors in its research and development and its general and administrative functions during the years ended December 31, 2022 and 2021 as follows:

	Year Ended December 31,
	2022		2021
Research and development	$	11,278	$	101,754
Selling, general and administrative		1,447,431		1,777,200
Total stock-based compensation expense	$	1,458,709	$	1,878,954

Summary of Common Stock Reserved for Future Issuance

Common stock reserved for future issuance consists of the following at December 31, 2022 and 2021:

	December 31,
	2022		2021
Stock options issued and outstanding		491,851		417,788
Authorized for future option grants		146,497		121,974
Warrants to purchase common stock	—			139,972
Authorized for employee stock purchase plan		37,048		28,715
Total common stock reserved for future issuance		675,396		708,449