Related Party Transactions	9 Months Ended
Sep. 30, 2021
Related Party Transactions [Abstract]
Related Party Transactions	9. Related Party Transactions On October 27, 2017, the Company entered into a Credit and Security Agreement and a Series B Convertible Preferred Stock Purchase Agreement with a private equity firm (“2017 Transaction”). The 2017 Transaction provided for the 2017 Term Loan, the issuance of Series B Preferred Stock (“Series B Preferred Stock”), and the issuance of a warrant to purchase Series B Preferred Stock (“Series B Preferred Stock Purchase Warrant”). The 2017 Term Loan accrued interest at a rate per annum equal to 9.5% and was due October 27, 2022. The 2017 Term Loan contained customary covenants, including a requirement to maintain a minimum unrestricted cash balance at all times of at least $5.0 million, and was secured by all tangible and intangible property and assets of the Company, with the exception of its intellectual property. The total proceeds of $124.2 million from the 2017 Transaction were allocated to the 2017 Term Loan, Series B Preferred Stock, and the Series B Preferred Stock Purchase Warrant based on the relative fair value of the term loan, equity, and warrant issued. As a result, the Company allocated proceeds of $65.7 million to the 2017 Term Loan. As the proceeds allocated to the 2017 Term Loan are lower than the stated loan amount of $75.0 million, the resulting $9.3 million discount was amortized as interest expense using the effective interest method over the term of the loan. During the three and nine months ended September 31, 2020, the Company recognized interest expense of $2.4 million and $7.1 million, inclusive of $0.6 million and $1.7 million of discount amortization, respectively. The Term Loan was discharged in December 2020 in connection with the offering of Convertible Notes. In connection with the Company’s initial public offering (“IPO”), on June 18, 2020, the Series B Preferred Stock Purchase Warrant became exercisable for 400,160 shares of common stock. On March 31, 2020, the Company entered into the First Amendment to the Credit Agreement (“Credit Agreement Amendment”), with the collateral agent and lender party thereto, providing for the payment of interest due and payable as of March 31, 2020 in shares of Series B Preferred Stock, and further providing for the payment of interest due and payable as of June 30, 2020 in shares of the Series B Preferred Stock in the event the IPO has not been consummated by such date. Pursuant to the Credit Agreement Amendment, the Company concurrently entered into a Series B Preferred Stock Subscription Agreement (“Subscription Agreement”), with the lender, which provided for the issuance of 967,130 shares of Series B Preferred Stock at a subscription price of $2.25 per share, as payment for interest due and payable as of March 31, 2020 and all applicable fees as set forth in the Credit Agreement Amendment. On May 8, 2020, the Company entered into an unsecured convertible promissory note (“Note”) with the same private equity firm pursuant to a note purchase agreement, in an aggregate principal amount of $15.0 million, with an annual interest rate of 8.0% and a maturity date of May 8, 2022. The Note was convertible into (i) common stock upon an initial public offering at the lesser of the conversion price then in effect and a conversion price equal to 80% of the public offering price (or, if not a “qualified IPO” as defined in the Company’s certificate of incorporation, at the election of a majority of the holders), (ii) on the maturity date or at the election of a majority of the holders, Series B preferred stock at an initial conversion price of $13.90 per share subject to certain adjustments, or (iii) at the election of a majority of the holders, shares of another class of equity securities issued by the Company in a future financing at 80% of the price per share of such class of equity securities issued in such offering. Interest under the Note was not generally payable except that if the Note is not converted pursuant to its terms on or prior to the maturity date and there are not sufficient authorized and unissued shares of Series B preferred stock for issuance upon the conversion of the Note on the maturity date, then the Company is required to pay all outstanding principal and any accrued and unpaid interest under the Note in cash. If the holders of the Note have not elected to convert the Note prior to, or in connection with, any sale transaction or a liquidation, dissolution or winding up of the Company, either voluntary or involuntary, then, upon any such sale transaction or liquidation, dissolution or winding up of the Company, the Company would have been required to pay in cash the outstanding principal balance of the Note, together with accrued and unpaid interest thereon, plus a make whole premium of 50% of the aggregate principal amount (less accrued and unpaid interest). The Company evaluated the economic features embedded in the Note and identified features that were required to be bifurcated and accounted for separately as a derivative. Accordingly, a derivative liability of $3.6 million was recorded on the issuance date of the Note and $3.8 million was subsequently reclassified to equity representing the fair value of the derivative liability on the date of extinguishment. The change in the fair value of the derivative liability of $0.2 million is included in interest and other income (expense), net in the accompanying condensed consolidated statements of operations for the nine months ended September 30, 2020. In June 2020, in connection with completion of the IPO, the Note was converted into 1,250,000 shares of common stock and all obligations under the Note were extinguished. Upon the conversion, the Company recorded a $3.6 million loss on extinguishment of the debt, which represented the difference between the carrying value of the Note and the derivative liability and the fair value of the shares of common stock issued to the Note holder of $3.4 million combined with amortization of the related debt discount of $0.2 million. The same private equity firm participated in the IPO and acquired 3,333,333 shares at a price of $15.00 per share, which was at par with the price to other investors. In December 2020, the private equity firm discharged any and all amounts owed and any obligations outstanding under the 2017 Term Loan in exchange for $78.5 million principal amount of Convertible Notes issued by the Company. The exchange was accounted for as an extinguishment of the 2017 Term Loan and resulted in $7.6 million of loss on extinguishment, which was included in interest and other income (expense), net in the consolidated statement of operations for the year ended December 31, 2020. This private equity firm also acquired an additional $25.0 million principal amount of the Company’s Convertible Notes for cash in this private offering, which resulted in $103.5 million aggregate principal amount of the Convertible Notes acquired by this private equity firm (see Note 8). As of September 30, 2021 and December 31, 2020, the accrued interest expense related to the Convertible Notes held by this private equity firm was $2.5 million and $0.5 million, respectively. In December 2020, the same private equity firm participated in the underwritten public offering and acquired 4,128,440 shares at a price of $3.27 per share, resulting in proceeds to the Company of $13.2 million before expenses. In June 2021, the private equity firm participated in a private placement and acquired 8,097,166 units, representing 8,097,166 shares of common stock and warrants to purchase up to 8,097,166 shares of common stock at a price of $2.47 per unit (see Note 12).

Related Party Transactions

9 Months Ended

Sep. 30, 2021

9. Related Party Transactions

On October 27, 2017, the Company entered into a Credit and Security Agreement and a Series B Convertible Preferred Stock Purchase Agreement with a private equity firm (“2017 Transaction”). The 2017 Transaction provided for the 2017 Term Loan, the issuance of Series B Preferred Stock (“Series B Preferred Stock”), and the issuance of a warrant to purchase Series B Preferred Stock (“Series B Preferred Stock Purchase Warrant”). The 2017 Term Loan accrued interest at a rate per annum equal to 9.5% and was due October 27, 2022.

The 2017 Term Loan contained customary covenants, including a requirement to maintain a minimum unrestricted cash balance at all times of at least $5.0 million, and was secured by all tangible and intangible property and assets of the Company, with the exception of its intellectual property.

The total proceeds of $124.2 million from the 2017 Transaction were allocated to the 2017 Term Loan, Series B Preferred Stock, and the Series B Preferred Stock Purchase Warrant based on the relative fair value of the term loan, equity, and warrant issued. As a result, the Company allocated proceeds of $65.7 million to the 2017 Term Loan. As the proceeds allocated to the 2017 Term Loan are lower than the stated loan amount of $75.0 million, the resulting $9.3 million discount was amortized as interest expense using the effective interest method over the term of the loan.

During the three and nine months ended September 31, 2020, the Company recognized interest expense of $2.4 million and $7.1 million, inclusive of $0.6 million and $1.7 million of discount amortization, respectively. The Term Loan was discharged in December 2020 in connection with the offering of Convertible Notes.

In connection with the Company’s initial public offering (“IPO”), on June 18, 2020, the Series B Preferred Stock Purchase Warrant became exercisable for 400,160 shares of common stock.

On March 31, 2020, the Company entered into the First Amendment to the Credit Agreement (“Credit Agreement Amendment”), with the collateral agent and lender party thereto, providing for the payment of interest due and payable as of March 31, 2020 in shares of Series B Preferred Stock, and further providing for the payment of interest due and payable as of June 30, 2020 in shares of the Series B Preferred Stock in the event the IPO has not been consummated by such date. Pursuant to the Credit Agreement Amendment, the Company concurrently entered into a Series B Preferred Stock Subscription Agreement (“Subscription Agreement”), with the lender, which provided for the issuance of 967,130 shares of Series B Preferred Stock at a subscription price of $2.25 per share, as payment for interest due and payable as of March 31, 2020 and all applicable fees as set forth in the Credit Agreement Amendment.

On May 8, 2020, the Company entered into an unsecured convertible promissory note (“Note”) with the same private equity firm pursuant to a note purchase agreement, in an aggregate principal amount of $15.0 million, with an annual interest rate of 8.0% and a maturity date of May 8, 2022. The Note was convertible into (i) common stock upon an initial public offering at the lesser of the conversion price then in effect and a conversion price equal to 80% of the public offering price (or, if not a “qualified IPO” as defined in the Company’s certificate of incorporation, at the election of a majority of the holders), (ii) on the maturity date or at the election of a majority of the holders, Series B preferred stock at an initial conversion price of $13.90 per share subject to certain adjustments, or (iii) at the election of a majority of the holders, shares of another class of equity securities issued by the Company in a future financing at 80% of the price per share of such class of equity securities issued in such offering. Interest under the Note was not generally payable except that if the Note is not converted pursuant to its terms on or prior to the maturity date and there are not sufficient authorized and unissued shares of Series B preferred stock for issuance upon the conversion of the Note on the maturity date, then the Company is required to pay all outstanding principal and any accrued and unpaid interest under the Note in cash. If the holders of the Note have not elected to convert the Note prior to, or in connection with, any sale transaction or a liquidation, dissolution or winding up of the Company, either voluntary or involuntary, then, upon any such sale transaction or liquidation, dissolution or winding up of the Company, the Company would have been required to pay in cash the outstanding principal balance of the Note, together with accrued and unpaid interest thereon, plus a make whole premium of 50% of the aggregate principal amount (less accrued and unpaid interest). The Company evaluated the economic features embedded in the Note and identified features that were required to be bifurcated and accounted for separately as a derivative. Accordingly, a derivative liability of $3.6 million was recorded on the issuance date of the Note and $3.8 million was subsequently reclassified to equity representing the fair value of the derivative liability on the date of extinguishment. The change in the fair value of the derivative liability of $0.2 million is included in interest and other income (expense), net in the accompanying condensed consolidated statements of operations for the nine months ended September 30, 2020. In June 2020, in connection with completion of the IPO, the Note was converted into 1,250,000 shares of common stock and all obligations under the Note were extinguished. Upon the conversion, the Company recorded a $3.6 million loss on extinguishment of the debt, which represented the difference between the carrying value of the Note and the derivative liability and the fair value of the shares of common stock issued to the Note holder of $3.4 million combined with amortization of the related debt discount of $0.2 million. The same private equity firm participated in the IPO and acquired 3,333,333 shares at a price of $15.00 per share, which was at par with the price to other investors.

In December 2020, the private equity firm discharged any and all amounts owed and any obligations outstanding under the 2017 Term Loan in exchange for $78.5 million principal amount of Convertible Notes issued by the Company. The exchange was accounted for as an extinguishment of the 2017 Term Loan and resulted in $7.6 million of loss on extinguishment, which was included in interest and other income (expense), net in the consolidated statement of operations for the year ended December 31, 2020. This private equity firm also acquired an additional $25.0 million principal amount of the Company’s Convertible Notes for cash in this private offering, which resulted in $103.5 million aggregate principal amount of the Convertible Notes acquired by this private equity firm (see Note 8). As of September 30, 2021 and December 31, 2020, the accrued interest expense related to the Convertible Notes held by this private equity firm was $2.5 million and $0.5 million, respectively. In December 2020, the same private equity firm participated in the underwritten public offering and acquired 4,128,440 shares at a price of $3.27 per share, resulting in proceeds to the Company of $13.2 million before expenses.

In June 2021, the private equity firm participated in a private placement and acquired 8,097,166 units, representing 8,097,166 shares of common stock and warrants to purchase up to 8,097,166 shares of common stock at a price of $2.47 per unit (see Note 12).