Takeda Asset Purchase and Stock Purchase Agreements (Tables)

12 Months Ended

Dec. 31, 2021

Series A Convertible Preferred Stock

Business Acquisition [Line Items]

Summary of Fair Value of Series A Convertible Preferred Stock Using Black-Scholes Option-pricing Model

Pursuant to the APA, in October 2021, the Company paid Millennium an upfront payment of $10.0 million in cash and issued to Millennium 1,000,000 shares of its Series A convertible preferred stock as referenced below. In determining the total purchase consideration paid to Millennium, the Series A convertible preferred stock shares were classified as level 3 in the valuation hierarchy due to the presence of significant unobservable inputs, and were valued upon issuance at $40.9 million using the Black-Scholes option-pricing model and the following assumptions:

		Description
Credit spread	12.4%	Allowance for counterparty credit risk of the Company given the liquidation preference and obligation to issue more shares as the stock price decreases
Probability of a Qualified    Financing	75%	As determined upon issuance date
Expected timing of a    Qualified Financing	0.5 years	As determined upon issuance date
Expected term	0.7 years	Weighted average of time to a Qualified Financing and time to the Mandatory Pricing Date, as determined upon issuance date
Volatility	55%	Based on the Company’s trading history for its common stock over the estimated term to the mandatory pricing date
Risk-free interest rate	0.08%	Based on the U.S. constant maturity treasury yield curve at the time of issuance over the expected term
Common stock price	$2.04	The Company's closing common stock price on October 15, 2021