On December 21, 2023, the Company entered into a royalty interest financing agreement, or the Royalty Interest Agreement, with United in Endeavour, LLC, or UiE, under which UiE acquired a portion of the Company's royalty interest in XACIATO. The Company received $5.0 million from UiE when the parties entered into the Royalty Interest Agreement (the "Initial Investment"), and between January 1, 2024 and December 31, 2026, the Company may, in its sole discretion, but subject to XOMA's prior written consent (see Note 8, Royalty Purchase Agreements), elect to receive three additional payments (each a "Supplemental Investment") from UiE of up to an aggregate of $7.0 million, for a total of up to $12.0 million.

Under the Royalty Interest Agreement, the Company agreed to make the following payments to UiE, until such time when UiE has received aggregate payments equaling a 12% internal rate of return (the “IRR”) on the Initial Investment and each Supplemental Investment, if any (the "Hard Cap"): (i) from December 21, 2023 through December 31, 2025, 50% of the amount of royalty payments remaining after all amounts that are due and payable and actually paid by the Company to any licensor or sublicensee on the royalty payments generated and received by the Company on net sales of XACIATO by Organon have been deducted (the “Net Royalty Payments”), (ii) from January 1, 2026 through December 31, 2029, 75% of the Net Royalty Payments, and (iii) from December 21, 2023 through December 31, 2029, 10% of the amount of milestone payments remaining after all amounts that are due and payable and actually paid by the Company to any licensor or sublicensee on the milestone payments generated and received by the Company on net sales of XACIATO by Organon have been deducted. After December 31, 2029, the Company will be required to make certain additional payments to UiE to the extent UiE has not received payments equaling the Hard Cap by December 31, 2029, December 31, 2033, and December 31, 2034, respectively. In addition, if UiE has not received payments equaling the Hard Cap by December 31, 2035 and the Company has other sources of assets or income besides XACIATO sufficient to complete such payments, the Company has agreed to pay UiE quarterly payments evenly divided over a two-year term, such that UiE will have obtained the IRR, taking into account all other payments received by UiE from the Company under the Royalty Interest Agreement. UiE’s right to receive payments will terminate when UiE has received payments in an amount equal to the Hard Cap.

The Company evaluated the terms of the Royalty Interest Agreement and concluded that the features of the Royalty Interest Agreement were similar to those of a debt instrument. As a result, the Company applied the debt recognition guidance under ASC 470, Debt, and recorded the Initial Investment as a liability related to the sale of future royalties (“Royalty Obligation”) which will be amortized under the effective interest method over the estimated term of the Royalty Interest Agreement. If the Company elects to receive additional Supplemental Investments, such additional Supplemental Investments will also be recorded as a liability related to the sale of future royalties when they are received and amortized under the interest method over the estimated remaining term of the Royalty Interest Agreement. In addition, in accordance with ASC 470, Debt, the Company will account for any royalties received in the future as non-cash royalty revenue in the consolidated statements of operations as a reduction to the debt balance.

As royalties and milestone payments are received by or on behalf of the Company from Organon and the Company subsequently pays or causes to be paid the amounts due to UiE in respect thereof in accordance with the Royalty Interest Agreement, the Royalty Obligation will be effectively repaid during the term of the Royalty Interest Agreement. In order to determine the amortization of the Royalty Obligation, the Company is required to estimate the total amount of future payments to UiE during the term of the Royalty Interest Agreement.

At execution of the Royalty Interest Agreement, the Company’s estimate of this total interest expense resulted in an effective annual interest rate of approximately 22.48%. This estimate contains significant assumptions that impact both the amount recorded at execution and the interest expense that will be recognized over the royalty period. The Company will periodically assess the estimated amounts due and payable to UiE and to the extent the amount or timing of such payments is materially different than the original estimates, an adjustment will be recorded prospectively to increase or decrease interest expense. There are a number of factors that could materially affect XACIATO's commercial success, and therefore the amount and timing of the Company's payments to UiE, and correspondingly, the amount of interest expense recorded by the Company, most of which are not within the Company’s control. Such factors include, but are not limited to, the capabilities of Organon and its commitment of sufficient resources to market, distribute and sell the product; timely and adequate commercial supply of the finished product and its components; perceived superiority of its cure rates compared to other available treatments; patient satisfaction and willingness to use it again and refer it to others; price pressure given the high level of generic treatments and changes in health care laws and regulations; adequate coverage, pricing and reimbursement from third-party payors; and approval of new entrants, including alternative, non-antibiotic treatment options. These factors could result in increases or decreases to both royalty revenues and interest expense.

In connection with entering into the Royalty Interest Agreement, the Company issued to UiE a warrant (the “Initial Royalty Warrant”) to purchase up to 422,805 shares of the Company’s common stock (see Note 4). In addition, for every $1,000,000 of Supplemental Investment, the Company will issue to UiE a warrant to purchase 84,561 shares of common stock, for an aggregate of warrants to purchase up to 591,927 shares of common stock (collectively the “Additional Royalty Warrants,” and together with the Initial Royalty Warrant, the “Royalty Interest Agreement Warrants”).