Stockholders' Equity (Deficit) (Tables)

12 Months Ended

Dec. 31, 2019

Summary of Unvested Shares

A summary of the Company’s unvested shares is as follows (in thousands):

	Number of Shares
Balance at December 31, 2018		100
Vested shares		(65	)
Balance at December 31, 2019		35

Summary of Stock Option Outstanding, Vested and Expected to Vest and Exercisable

	Number of Shares		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
December 31, 2019:
Options outstanding		1,662,253	$	4.17		9.2	$	1,460
Options vested and expected to vest		1,662,253	$	4.17		9.2	$	1,460
Options exercisable		244,170	$	1.16		7.2	$	718

Summary of Stock Option Activity

A summary of the Company’s stock option activity under the 2019 Plan and 2015 Plan is as follows:

	Number of Options			Weighted- Average Exercise Price
Balance at December 31, 2018		504,019		$	0.81
Granted		1,230,000		$	5.47
Cancelled		(52,726	)	$	3.38
Exercised		(19,040	)	$	0.69
Balance at December 31, 2019		1,662,253		$	4.17

Summary of Share-Based Compensation Expense

Stock-based compensation expense recognized for all equity awards has been reported in the statements of operations as follows (in thousands):

	Years Ended December 31,
	2019		2018
Research and development	$	237	$	141
General and administrative		270		39
	$	507	$	180

Common Stock Reserved for Future Issuance

Common stock reserved for future issuance is as follows (in thousands):

	December 31,
	2019		2018
Redeemable convertible preferred stock		—		8,148
Warrants to purchase convertible preferred stock		—		372
Common stock warrants		841		—
Common stock options issued and outstanding		1,958		504
Common stock available for issuance under equity    plans		495		80
		3,294		9,104

Stock Option Grants

Schedule of Assumptions Used to Determine Fair Value

The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of stock option grants were as follows:

	Years Ended December 31,
	2019			2018
Risk-free interest rate		1.6	%		2.9	%
Expected volatility		77.6	%		64.7	%
Expected term (in years)		6.0			6.1
Expected dividend yield		—	%		—	%