Convertible Preferred Stock, Tranche Liability and Warrant Liability (Tables)

6 Months Ended

Jun. 30, 2021

Convertible Preferred Stock Tranche Liability and Warrant Liability [Abstract]

Summary of Convertible preferred stock

Convertible preferred stock consisted of the following (in thousands, except share and per share data):

	June 30, 2021
	Shares Authorized		Shares Issued and Outstanding		Weighted Average Issuance Price per Share		Carrying Value		Liquidation Preference
Series A		711,203		477,297	$	2.24	$	1,067	$	1,067
Series A-1		11,898,177		7,985,305		2.27		22,963		18,097
Series B		29,457,450		19,770,070		3.80		150,474		75,116
Total		42,066,830		28,232,672			$	174,504	$	94,280

	December 31, 2020
	Shares Authorized		Shares Issued and Outstanding		Weighted Average Issuance Price per Share		Carrying Value		Liquidation Preference
Series A		711,203		477,297	$	2.24	$	1,067	$	1,067
Series A-1		11,898,177		7,537,879		2.24		16,333		16,847
Series B		29,457,450		11,862,043		3.80		39,253		45,070
Total		42,066,830		19,877,219			$	56,653	$	62,984

Summary of Assumptions Used in Estimating the Fair Value of Preferred Stock Tranche Liability

The following assumptions were used in the estimation of the fair value of the tranche liability as a forward contract as of each of the dates indicated:

	June 17, 2021	December 31, 2020
Risk-free interest rate	0.07%	0.12%
Expected time to Milestone Closing (in years)	0.8	1.3
Probability of achievement of Milestone Closing	100%	65%

Summary of Fair Value of the Warrant Liability

The following assumptions were used in the estimation of the fair value of the warrant liability using the OPM backsolve method as of each of the dates indicated:

	June 22, 2021		December 31, 2020
Risk-free interest rate		0.25%		0.13%
Expected term (in years)		2.0		2.0
Expected volatility		90%		90%
Expected dividend yield	0%		0%

Summary of the Tranche Liability and Warrant Liability Measured at Fair Value using Level 3 Significant Unobservable Inputs

The following table provides a reconciliation of the tranche liability and warrant liability measured at fair value using Level 3 significant unobservable inputs (in thousands):

	Series A-1 Preferred Stock Warrant			Series B Tranche Rights			Total
Balance, December 31, 2020	$	380		$	5,033		$	5,413
Change in fair value		5,000			76,157			81,157
Settlement of tranche liability due to issuance of Milestone Shares		—			(81,190	)		(81,190	)
Settlement of warrant liability upon exercise of warrant		(5,380	)		—			(5,380	)
Balance, June 30, 2021	$	—		$	—		$	—