NKGen Biotech (NKGN) adds $343,000 under AlpineBrook note

Rhea-AI Filing Summary

NKGen Biotech, Inc. entered into a fourth amendment to its secured promissory note with AlpineBrook Capital GP I Limited on February 20, 2026. This amendment provides an additional $343,000 in funding, called the Fifth Additional New Loan.

Following this change, the principal amount outstanding under the note increased to $27,101,106. The amendment also clarifies that interest on the new $343,000 loan begins accruing from February 20, 2026, the date the additional funding was provided.

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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): February 20, 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 February 20, 2026, NKGen Biotech, Inc. (the “Company”) and NKGen Operating Biotech, Inc., a Delaware corporation (together with the Company, the “Borrowers”), entered into a fourth amendment (the “Alpine Fourth Amendment”) to that certain secured promissory note with AlpineBrook Capital GP I Limited, dated January 5, 2026, as amended by that certain amendment to secured promissory note dated January 12, 2026, that certain amendment no. 2 to secured promissory note dated January 23, 2026, and that certain amendment no. 3 to secured promissory note dated January 30, 2026 (the “Note”).

The Alpine Fourth Amendment provides an additional $343,000 of funding to the Borrowers (the “Fifth Additional New Loan”). As a result, the principal amount of the Note was increased to $27,101,106. The Alpine Fourth Amendment also clarifies that interest on the Fifth Additional New Loan accrues from February 20, 2026 (the date on which the Fifth Additional New Loan was funded).

The foregoing description of the Alpine Fourth Amendment does not purport to be complete and is qualified in its entirety by the terms and conditions of the Alpine Fourth Amendment, 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.

Item 9.01. Financial Statements and Exhibits

(d) Exhibits.

Exhibit No.		Description
10.1		Amendment No. 4 to Secured Promissory Note issued to the AlpineBrook Capital GP I Limited, dated February 20, 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: February 26, 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) announce in this 8-K filing?

NKGen Biotech announced a fourth amendment to its secured promissory note with AlpineBrook Capital GP I Limited, adding a new $343,000 loan and updating the total principal and interest start date for this additional funding.

How much additional funding did NKGen Biotech (NKGN) receive under the AlpineBrook note?

NKGen Biotech received an additional $343,000 of funding under the secured promissory note with AlpineBrook. This new amount is referred to as the Fifth Additional New Loan and increases the overall debt owed to the lender under the existing note.

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

After the fourth amendment, the principal amount of NKGen Biotech’s secured promissory note with AlpineBrook Capital GP I Limited increased to $27,101,106, reflecting the addition of the $343,000 Fifth Additional New Loan to prior outstanding principal.

When does interest start accruing on NKGen Biotech’s new $343,000 loan?

Interest on NKGen Biotech’s new $343,000 Fifth Additional New Loan begins accruing from February 20, 2026, which is the date the additional funding was provided to the borrowers under the amended secured promissory note.

Who are the borrowers under NKGen Biotech’s amended secured promissory note?

The borrowers are NKGen Biotech, Inc. and NKGen Operating Biotech, Inc., both Delaware corporations. They are jointly party to the secured promissory note with AlpineBrook Capital GP I Limited, as amended on February 20, 2026.

What exhibit did NKGen Biotech file related to this loan amendment?

NKGen Biotech filed Amendment No. 4 to the Secured Promissory Note issued to AlpineBrook Capital GP I Limited as Exhibit 10.1, along with a cover page interactive data file labeled Exhibit 104 in the same submission.

Filing Exhibits & Attachments

5 documents

Agreements & Contracts

• EX-10.1 AMENDMENT NO. 4 TO SECURED PROMISSORY NOTE ISSUED TO THE ALPINEBROOK CAPITAL GP 17.4 KB

Other Documents

• EX-101 XBRL SCHEMA FILE 3.8 KB
• EX-101 XBRL DEFINITION FILE 26.2 KB
• EX-101 XBRL LABEL FILE 36.1 KB
• EX-101 XBRL PRESENTATION FILE 24.8 KB