In August 2020, the Company issued a $6.5 million convertible promissory note (“Convertible Promissory Note”). The Convertible Promissory Note accrued interest at a rate of 6% a year with maturity date two years from issuance.

The Convertible Promissory Note could be converted or redeemed as follows (i) automatically converted in a qualified Series B financing transaction from which the Company would receive total gross proceeds of not less than $5.0 million at a conversion price equal to 85% of the per share price paid by investors for such securities, (ii) automatically converted upon initial public offering at a conversion price equal to 85% of the per share price off common stock in the initial public offering, (iii) optionally converted into Series A-3 preferred stock if a change in control, initial public offering, or

qualified Series B financing had not occurred prior to the maturity date at a price equal to an amount determined by dividing $140 million by the fully diluted capitalization of the Company at the time of conversion, or (iv) repaid upon a change in control for an amount equal to the issue price plus accrued and unpaid interest or an amount as would have been payable if the noteholders had optionally converted into shares of Series A-3 preferred stock. The Convertible Promissory Note was converted in March 2021 in connection with the Series B financing.

The Convertible Promissory Note was accounted for in accordance with ASC 470-20, Debt with Conversion and Other Options (“ASC 470-20”) and ASC 815-15, Derivatives and Hedging - Embedded Derivatives (“ASC 815-15”). Under ASC 815-15, an embedded feature is required to be bifurcated if all three conditions are met: (1) economic characteristics and risks of the embedded derivative are not clearly and closely related to the economic characteristics and risks of the host contract, (2) the hybrid instrument is not remeasured at fair value under otherwise applicable GAAP with changes in fair value reported in earnings as they occur, and (3) a separate instrument which the same terms as the embedded derivative would be considered a derivative instrument subject to derivative accounting (the initial net investment for the hybrid instrument should not be considered to be the initial net investment for the embedded derivative. The Company bifurcated certain features that were required to be accounted separately for as a single embedded derivative. The initial fair value of this derivative of $1.8 million was recorded as a liability, and as a reduction to the carrying value of the Convertible Promissory Note. The Company also incurred a negligible amount of issuance costs related to the Convertible Promissory Note, which were also recorded as a reduction to the Convertible Promissory Note on the balance sheet.

The debt discount comprised the initial fair value of the derivative liability and the issuance costs, and was amortized using the effective interest method over the two-year contractual term of the Convertible Promissory Note and presented as a direct reduction of the debt liability. The debt discount was being amortized at an effective interest rate of 23.8%.

Interest expense incurred in connection with the Convertible Promissory Note consisted of the following (in thousands):


	Year Ended December 31, 2021
Coupon interest at 6%	$	86
Accretion of discount and amortization of issuance costs		177
Total interest expense on Convertible Promissory Note	$	263

On March 19, 2021, in connection with the closing of the Series B convertible preferred stock financing, the Convertible Promissory Note (including accrued interest) and derivative liability converted into 2,805,850 shares of Series B-2 convertible preferred stock at an issuance price of $2.39846 per share. As a result of the conversion, the Company recorded a loss on extinguishment of convertible promissory notes of $0.8 million of other expense in the statements of operations and comprehensive loss for the year ended December 31, 2021, which included the unamortized debt issuance costs.