In May 2026, the Company entered into the Revenue Share Agreement with BXLS. Pursuant to the Revenue Share Agreement, in exchange for an upfront payment of $100.0 million (the “Tranche 1 Funding”), BXLS purchased from the Company the right to receive tiered revenue share payments (“Revenue Share Payments”) with respect to annual worldwide net product sales (“Net Sales”) of zumilokibart. In addition, under the Revenue Share Agreement:

The Revenue Share Payments are based on tiered percentage rates of aggregate annual Net Sales of zumilokibart (“Annual Aggregate Product Net Sales”). Under the Revenue Share Agreement, the revenue percentage payable to BXLS is the sum of (a) the base revenue percentage (the “Base Revenue Percentage”) and (b) the tranche 4 revenue percentage (the “Tranche 4 Revenue Percentage” and, together with the Base Revenue Percentage, the “Revenue Percentages”), which applies only from and after the Tranche 4 Funding.

The Tranche 4 Revenue Percentage is subject to a cap of $1.0 billion in aggregate Tranche 4-related Revenue Share Payments to BXLS, after which the Tranche 4 Revenue Percentage for Tier 1 decreases to 0.00%.

The Revenue Share Payments will be payable during a term commencing on the date of the first commercial sale of zumilokibart and ending on the fifteenth (15th) anniversary of the date of receipt of marketing approval for zumilokibart.

If the Company consummates a change of control with a third party, the Company will be required to pay a certain specified amount to BXLS and would also receive credits against future Revenue Share Payments otherwise payable to BXLS following the consummation of the change of control.

In the alternative, at any time following execution of a definitive agreement for a change of control, the Company (or the surviving entity) may elect, in lieu of the required payment described above, to pay BXLS a specified amount calculated under the Revenue Share Agreement to buy down a portion of future Revenue Share Payments (each, a "Buy-Back Option"). If the Company exercises a Buy-Back Option, the Revenue Percentage will be adjusted downward in accordance with the Revenue Share Agreement, and if the Buy-Back Option is exercised prior to the Tranche 4 Trigger, BXLS will no longer be obligated to pay the Tranche 4 Funding, and in such case the Tranche 4 Revenue Percentages across all tiers will be 0.00%.

The Company has accounted for the Revenue Share Agreement as a debt financing arrangement in accordance with FASB ASC Topic 470, Debt, because the Company retains significant continuing involvement in generating the underlying revenue on which the Revenue Share Payments are calculated. Funds received under the Revenue Share Agreement are recorded, net of issuance costs, within non-current liabilities and are disclosed as the revenue share liability on the condensed consolidated balance sheet. The revenue share liability and related interest expense are calculated based on the amount of funding received, as well as the Company's estimates of the timing and amount of future Revenue Share Payments expected over the estimated term of the agreement, and are amortized using the effective interest method.

Upon receipt, Tranche 1 Funding was recorded as a liability and debt issuance costs of $2.3 million were recorded as a direct deduction from the carrying amount of the liability. As of June 30, 2026, the effective interest rate was approximately 16.4%. For the three and six months ended June 30, 2026, the Company recognized $1.6 million in interest expense.

The Company's estimates of future Revenue Share Payments involve significant judgment and are based on a number of assumptions, including expected regulatory and commercial launch timelines, projected net product sales and probability of success over the term of the Revenue Share Agreement. Changes in these assumptions could have a material impact on the effective interest rate.

As described in Note 1, the Company has entered into a Merger Agreement with AbbVie and, accordingly, the option to make the Buy-Back Payment described above is currently available to the Company. If the Merger closes, the Buy-Back Option is not exercised within the required timeframe, and no additional tranches have been funded after the Tranche 1 Funding, the Company will be required to pay $100.0 million to BXLS and would also receive credits against future Revenue Share Payments. As of June 30, 2026, the Company classified the revenue share liability as long-term because the Merger had not yet closed.