NKGen Biotech (NASDAQ: NKGN) expands secured promissory note to $26.1M

Rhea-AI Filing Summary

NKGen Biotech, Inc. reported that on January 12, 2026, it and its subsidiary NKGen Operating Biotech, Inc. amended an existing secured promissory note with AlpineBrook Capital GP I Limited. The amendment provides an additional $295,000 in funding, called the Second Additional New Loan, increasing the total principal amount of the note to $26,135,106.

The amendment also specifies how interest accrues on the different portions of the debt. Interest on $25,840,106 of principal continues to accrue from January 5, 2026, the date of the original note, while interest on the new $295,000 portion begins accruing from January 12, 2026, the date the amendment was executed.

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15 (d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): January 12, 2026

NKGen Biotech, Inc.

(Exact name of registrant as specified in its charter)

Delaware		001-40427		86-2191918
(State or other jurisdiction of incorporation)		(Commission File Number)		(IRS Employer Identification No.)

3001 Daimler Street

Santa Ana, CA, 92705

(Address of principal executive offices and zip code)

Registrant’s telephone number, including area code: (949) 396-6830

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2 below):

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class		Trading Symbol(s)		Name of each exchange on which registered
Common Stock, $0.0001 par value per share		NKGN		OTC Expert Market
Warrants, each whole warrant exercisable for one share of Common Stock at an exercise price of $11.50 per share		NKGNW		OTC Expert Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 1.01. Entry into a Material Definitive Agreement.

On January 12, 2026, NKGen Biotech, Inc., a Delaware corporation (the “Company”), and NKGen Operating Biotech, Inc., a Delaware corporation (together with the Company, the “Borrowers”), entered into an amendment (the “Amendment”) to that certain secured promissory note with AlpineBrook Capital GP I Limited (the “Lender”), dated January 5, 2026 (the “Note”).

The Amendment provides an additional $295,000 of funding to the Borrowers (the “Second Additional New Loan”). As a result, the principal amount of the note was increased to $26,135,106. The Amendment also clarifies that interest on $25,840,106 of the principal amount accrues from January 5, 2026 (the date of the original Note), and that interest on the Second Additional New Loan accrues from January 12, 2026 (the date on which the Amendment was entered into).

The foregoing description of the Amendment does not purport to be complete and is qualified in its entirety by reference to the full text of the Amendment, which the Company intends to file as an exhibit to this Current Report on Form 8-K.

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.

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Item 9.01. Financial Statements and Exhibits

(d) Exhibits.

Exhibit No.		Description
10.1		Amendment to Secured Promissory Note issued to the AlpineBrook Capital GP I Limited, dated January 12, 2026.
104		Cover Page Interactive Data File (embedded within the Inline XBRL document)

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SIGNATURES

Pursuant to the requirements of Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	NKGEN BIOTECH, INC.
Date: January 16, 2026	/s/ Paul Y. Song
	Name:	Paul Y. Song
	Title:	Chief Executive Officer
		(Principal Executive Officer)

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FAQ

What did NKGen Biotech (NKGN) disclose in this 8-K filing?

NKGen Biotech, Inc. disclosed that it entered into an amendment to a secured promissory note with AlpineBrook Capital GP I Limited, adding new funding and updating interest terms.

How much additional funding did NKGen Biotech receive under the amended note?

The amendment provides an additional $295,000 of funding to NKGen Biotech, Inc. and its subsidiary as the Second Additional New Loan.

What is the new total principal amount of NKGen Biotech’s promissory note?

After the amendment, the principal amount of the secured promissory note with AlpineBrook Capital GP I Limited increased to $26,135,106.

How is interest accrual structured on NKGen Biotech’s amended note?

Interest on $25,840,106 of principal accrues from January 5, 2026, the date of the original note, and interest on the additional $295,000 accrues from January 12, 2026, the date of the amendment.

Who are the borrowers and lender under NKGen Biotech’s amended note?

The borrowers are NKGen Biotech, Inc. and NKGen Operating Biotech, Inc., and the lender is AlpineBrook Capital GP I Limited.

What items of the 8-K does this NKGen Biotech filing relate to?

The disclosure relates to Item 1.01 (Entry into a Material Definitive Agreement) and Item 2.03 (Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement).