Material Agreement, Financial Obligation (Form 8-K)

Item 1.01. Entry into a Material Definitive Agreement.

On January 5, 2026, NKGen Biotech, Inc., a Delaware corporation (the "Company"), and NKGen Operating Biotech, Inc., a Delaware corporation (the "Company Sub," and together with the Company, the "Borrowers"), entered into a secured promissory note (the "Note") with AlpineBrook Capital GP I Limited (the "Lender"), in the original principal amount of $25,840,106, bearing interest at 12% per annum and maturing initially on the date falling two months after issuance, subject to extension at the Lender's discretion. The Note documents and evidences certain undocumented cash advances made by the Lender to the Borrowers since late 2024, primarily in connection with the Company's acquisition of a majority stake in NKGen Biotech Korea Co., Ltd. (f/k/a NKMax Co., Ltd.) ("NKGen Korea") through the Korean bankruptcy process, together with accrued interest, fees and expenses associated with such advances, which totaled $25,540,106 immediately prior to issuance. In addition, the Note reflects an incremental $300,000 advanced by the Lender contemporaneously with execution, which is the only new capital funded in connection with the Note. The Note prohibits prepayment before the applicable maturity date without lender consent.

The Note includes a "most favored nation" provision applicable to future debt or equity financings of the Borrowers or any of their subsidiaries (including NKGen Korea). During the term of the Note, if either Borrower or any of its subsidiaries undertakes any subsequent debt or equity financing containing terms more favorable than those in the Note, the Borrowers must notify the Lender and provide the benefit of such more favorable terms to the Lender. The provision expressly covers, without limitation, economic terms (including interest rate), collateral, conversion price and related economics, warrant coverage, governance rights, information rights, director appointment rights, preemptive rights, and rights of first refusal.

Upon a Change of Control (as defined in the Note) of either Borrower, the Note requires repayment in cash of outstanding principal plus accrued but unpaid interest, together with a cash premium equal to 20% of the then-outstanding principal amount. Borrowers must provide notice at least 10 business days' advance notice of any such transaction.

If an event of default occurs and is continuing, all outstanding obligations under the Note bear default interest at a rate of 24% per annum, calculated on a 360-day year and payable on demand.

The Note contains restrictive covenants that, among other things, limit additional indebtedness and the granting of liens, subject to limited customary baskets and existing liens in favor of East West Bank ("EWB") and BDW Investments LLC ("BDW"). The covenant package also restricts equity issuances and changes to the capital structure, subject to ordinary-course exceptions (including plan-based equity awards, exercises, and ministerial adjustments), and includes a negative pledge whereby the Borrowers and their subsidiaries (including NKGen Korea) may not grant collateral or guarantees in favor of third parties without the Lender's prior written consent.

Pursuant to the Note, the Borrowers granted the Lender security interests in certain collateral, subject to existing liens in favor of EWB and BDW, respectively. The security interests will not be perfected unless and until consents from said secured creditors are obtained, and all grants are subordinate to existing liens. The collateral package includes (1) a security interest in substantially all U.S. personal property of the Borrowers; (2) a deed of trust and an assignment of leases and rents with respect to U.S. real property owned or hereafter owned by the Company Sub, to be executed and delivered in agreed form following execution of the Note, subject to consents of EWB and BDW; and (3) security arrangements under Korean law relating to the Company's shares of NKGen Korea, and related account collateral. Additionally, the Note requires the Company to use commercially reasonable best efforts to cause NKGen Korea to provide an unconditional guarantee of the Borrowers' obligations and to grant a first-priority security interest over substantially all of NKGen Korea's assets to secure that guarantee (subject to NKGen Korea board approval, certain waivers/consents, and compliance with applicable law).

Additionally, the Note grants the Lender a right of first refusal over any proposed transfer or other disposition by the Company of its shares of NKGen Korea, on terms generally consistent with the third-party offer.

The foregoing description of the Note does not purport to be complete and is qualified in its entirety by the terms and conditions of the Note which is filed as Exhibit 10.1 to this Current Report on Form 8-K and incorporated herein by reference.

Item 2.03. Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant.

The disclosures set forth in Item 1.01 are incorporated by into this Item 2.03 by reference.