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): September 17, 2025

TONIX PHARMACEUTICALS HOLDING CORP. 

(Exact name of registrant as specified in its charter)

26 Main Street, Chatham, New Jersey, 07928

(Address of principal executive offices) (Zip Code)

Registrant’s telephone number, including area code: (862) 904-8182

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:

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. ☐

On September 17, 2025, Tonix Pharmaceuticals Holding Corp. (the “Company”) announced the in-licensing of worldwide rights to its TNX-4800 (formerly known as mAb 2217LS) product candidate. A copy of the press release which discusses this matter is furnished hereto as Exhibit 99.01, and incorporated herein by reference.

The information in this Item 7.01 of this Current Report on Form 8-K, including Exhibit 99.01 attached hereto, shall not be deemed “filed” for purposes of Section 18 of the United States Securities Exchange Act of 1934 (the “Exchange Act”) or otherwise subject to the liabilities of that section, nor shall they be deemed incorporated by reference in any filing under the United States Securities Act of 1933 or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

On September 17, 2025, the Company announced the in-licensing of worldwide rights to TNX-4800, a long-acting human monoclonal antibody that targets the outer surface protein A (“OspA”) of Borrelia burgdorferi, the causative agent of Lyme disease in humans. TNX-4800 was developed by researchers at UMass Chan Medical School. TNX-4800 is a fully human monoclonal antibody with an engineered extended half-life that targets the OspA on Lyme-causing Borrelia bacteria. By binding OspA, TNX-4800 blocks the maturation of Borrelia burgdorferi in the mid-gut of infected deer ticks. The mAb 2217LS was derived from mAb 2217 by amino acid substitutions that crystallizable fragment domain to prolong the serum half-life. A single subcutaneous springtime administration is designed to maintain protective antibody titers through the Fall, or the entire U.S. tick season, providing pre-exposure prophylaxis against Lyme disease without relying on the recipient’s immune system to generate antibodies. By delivering a well-characterized antibody directly, TNX-4800 has been shown to block transmission of the major Borrelia genospecies from ticks to animals. TNX-4800 sidesteps the multidose schedules required for OspA vaccines in development and FDA-approved vaccines that have been withdrawn from the market due to concerns about increased risk of autoimmunity. The Company intends to advance TNX-4800 through additional clinical trials with the goal of submitting a Biologics Licensing Application to the U.S. Food and Drug and Administration.

Forward-Looking Statements 

This Current Report on Form 8-K contains certain forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934 and Private Securities Litigation Reform Act, as amended, including those relating to the Company’s product development, clinical trials, clinical and regulatory timelines, market opportunity, competitive position, possible or assumed future results of operations, business strategies, potential growth opportunities and other statement that are predictive in nature. These forward-looking statements are based on current expectations, estimates, forecasts and projections about the industry and markets in which we operate and management’s current beliefs and assumptions.

These statements may be identified by the use of forward-looking expressions, including, but not limited to, “expect,” “anticipate,” “intend,” “plan,” “believe,” “estimate,” “potential,” “predict,” “project,” “should,” “would” and similar expressions and the negatives of those terms. These statements relate to future events or our financial performance and involve known and unknown risks, uncertainties, and other factors which may cause actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. Such factors include those set forth in the Company’s filings with the SEC. Prospective investors are cautioned not to place undue reliance on such forward-looking statements, which speak only as of the date of this press release. The Company undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events or otherwise.

SIGNATURE

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