Derivative liabilities and redeemable convertible preferred stock liability	12 Months Ended
Dec. 31, 2021
Derivative Liabilities And Redeemable Convertible Preferred Stock Liability [Abstract]
Derivative liabilities and redeemable convertible preferred stock liability	7. Derivative liabilities and redeemable convertible preferred stock liability Warrants In connection with the issuance of the Notes, Lenders were issued Warrants to purchase 134,112 shares of the Company’s capital stock. The Warrants have a coverage percentage of 25% of the principal amount of the Notes and have a ten-year expiration date from the applicable closing date of April 20, 2018 or June 6, 2018. The underlying shares issuable upon the exercise of the Warrants were eligible to be converted into the next round of equity financing. The Warrants became exercisable into shares of Series A for an exercise price of $9.32 per share. The Company recorded the Warrants initially at fair value (Note 10) as derivative liabilities on the consolidated balance sheet with the remaining value being allocated to the Notes as a debt discount. The fair value of the Warrants upon issuance on April 20, 2018 and June 6, 2018, was $0.7 million and $238,000, respectively. Due to the IPO in October 2020, all outstanding warrants as of December 31, 2020 were automatically exercised for the issuance of Common Stock, and following that exercise, such warrants were no longer outstanding. As Series A contains a conditional obligation for the Company to repurchase the shares for cash consideration, the Warrants remain outstanding as derivative liabilities with changes in fair value being recorded on the consolidated statements of operations and comprehensive loss. For the year ended December 31, 2020, the Company recorded a change in fair value of derivative liabilities $296,000. Redeemable convertible preferred stock liability In connection with the issuance of Series B-1 Redeemable Convertible Preferred Stock (the Series B-1) (Note 8), the Series B-1 preferred stockholders committed to purchase and the Company committed to sell 3,569,630 shares of Series B-2 Redeemable Convertible Preferred Stock (the Series B-2) at a price of $11.20563 per share in a subsequent closing, contingent upon the achievement of certain developmental milestones or a receipt of a waiver of achievement of the milestones. The Redeemable Convertible Preferred Stock Liability is considered a freestanding instrument that qualifies as a liability under ASC Topic 480, Distinguishing Liabilities from Equity (ASC 480) as the Company is committed to issue an instrument that ultimately may require a transfer of assets. The liability is accounted for at fair value and re-measured at each reporting date (Note 10). On the date of the initial closing, the Company recorded the Redeemable Convertible Preferred Stock Liability at a fair value of $3.2 million. As of December 31, 2020, all Series B-2 shares were issued. As a result of the IPO, the Series B-2 shares converted to shares of common stock. The Company recorded a change in fair value of the liability of $11.4 million for the year ended December 31, 2020 included in interest and other (expense) income, net. The convertible preferred stock liability was retired as of the IPO.

Derivative liabilities and redeemable convertible preferred stock liability

12 Months Ended

Dec. 31, 2021

Derivative Liabilities And Redeemable Convertible Preferred Stock Liability [Abstract]

Derivative liabilities and redeemable convertible preferred stock liability

7. Derivative liabilities and redeemable convertible preferred stock liability

Warrants

In connection with the issuance of the Notes, Lenders were issued Warrants to purchase 134,112 shares of the Company’s capital stock. The Warrants have a coverage percentage of 25% of the principal amount of the Notes and have a ten-year expiration date from the applicable closing date of April 20, 2018 or June 6, 2018.

The underlying shares issuable upon the exercise of the Warrants were eligible to be converted into the next round of equity financing. The Warrants became exercisable into shares of Series A for an exercise price of $9.32 per share.

The Company recorded the Warrants initially at fair value (Note 10) as derivative liabilities on the consolidated balance sheet with the remaining value being allocated to the Notes as a debt discount. The fair value of the Warrants upon issuance on April 20, 2018 and June 6, 2018, was $0.7 million and $238,000, respectively. Due to the IPO in October 2020, all outstanding warrants as of December 31, 2020 were automatically exercised for the issuance of Common Stock, and following that exercise, such warrants were no longer outstanding.

As Series A contains a conditional obligation for the Company to repurchase the shares for cash consideration, the Warrants remain outstanding as derivative liabilities with changes in fair value being recorded on the consolidated statements of operations and comprehensive loss. For the year ended December 31, 2020, the Company recorded a change in fair value of derivative liabilities $296,000.

Redeemable convertible preferred stock liability

In connection with the issuance of Series B-1 Redeemable Convertible Preferred Stock (the Series B-1) (Note 8), the Series B-1 preferred stockholders committed to purchase and the Company committed to sell 3,569,630 shares of Series B-2 Redeemable Convertible Preferred Stock (the Series B-2) at a price of $11.20563 per share in a subsequent closing, contingent upon the achievement of certain developmental milestones or a receipt of a waiver of achievement of the milestones. The Redeemable Convertible Preferred Stock Liability is considered a freestanding instrument that qualifies as a liability under ASC Topic 480, Distinguishing Liabilities from Equity (ASC 480) as the Company is committed to issue an instrument that ultimately may require a transfer of assets. The liability is accounted for at fair value and re-measured at each reporting date (Note 10). On the date of the initial closing, the Company recorded the Redeemable Convertible Preferred Stock Liability at a fair value of $3.2 million.

As of December 31, 2020, all Series B-2 shares were issued. As a result of the IPO, the Series B-2 shares converted to shares of common stock. The Company recorded a change in fair value of the liability of $11.4 million for the year ended December 31, 2020 included in interest and other (expense) income, net. The convertible preferred stock liability was retired as of the IPO.