Tonix Pharmaceuticals (Nasdaq: TNXP) details TNX-1500 Phase 1 results and kidney transplant Phase 2 plan

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8-K

Rhea-AI Filing Summary

Tonix Pharmaceuticals Holding Corp. reported that Phase 1 clinical data for its investigational monoclonal antibody TNX-1500 were published in the Journal of Clinical Immunology. In a first-in-human study of 26 healthy adults, single intravenous doses of 3, 10, or 30 mg/kg were generally well tolerated, with no serious adverse events and only mild, transient aphthous ulcers deemed possibly related to TNX-1500.

TNX-1500 significantly suppressed T cell-dependent antibody responses to the KLH antigen, blocking primary responses at all doses and secondary responses at 10 and 30 mg/kg, with about a 70% reduction at 3 mg/kg versus placebo. Pharmacokinetic data showed dose-proportional exposure and terminal half-lives around 34–38 days, supporting monthly dosing. Tonix highlighted that a Phase 2 investigator-initiated study in kidney transplant recipients at Massachusetts General Hospital is expected to begin in the second half of 2026, pending FDA clearance of the IND.

Insights

Early Phase 1 TNX-1500 data show target engagement and tolerability but remain preliminary.

Tonix Pharmaceuticals presented Phase 1 results for TNX-1500, an anti-CD40L monoclonal antibody being developed to prevent organ transplant rejection and treat autoimmune diseases. The first-in-human trial in 26 healthy adults used single ascending doses of 3, 10, and 30 mg/kg.

Across cohorts, TNX-1500 was generally well tolerated, with no serious adverse events or discontinuations. The only treatment-emergent adverse event considered possibly related to the drug was mild aphthous ulcer in one participant per active-dose group, resolving within 2–10 days. No injection or administration site reactions were reported.

Pharmacodynamic data showed TNX-1500 blocked primary T cell-dependent antibody responses to KLH at all doses and secondary responses at 10 and 30 mg/kg, with about a 70% reduction in secondary response at 3 mg/kg versus placebo. Pharmacokinetics suggested dose-proportional exposure and half-lives of 37.8 and 33.8 days at 10 and 30 mg/kg, consistent with monthly intravenous dosing. A small, five-patient Phase 2 investigator-initiated kidney transplant study at MGH is expected in the second half of 2026, pending FDA IND clearance, so clinical relevance in patients will depend on those future results.

8-K Event Classification

3 items: 7.01, 8.01, 9.01

3 items

Item 7.01 Regulation FD Disclosure Disclosure

Material non-public information disclosed under Regulation Fair Disclosure, often investor presentations or guidance.

Item 8.01 Other Events Other

Voluntary disclosure of events the company deems important to shareholders but not covered by other items.

Item 9.01 Financial Statements and Exhibits Exhibits

Financial statements, pro forma financial information, and exhibit attachments filed with this report.

Key Figures

Phase 1 participants: 26 healthy adult volunteers Dose levels: 3, 10, and 30 mg/kg Follow-up duration: 120 days +5 more

8 metrics

Phase 1 participants 26 healthy adult volunteers First-in-human TNX-1500 study population

Dose levels 3, 10, and 30 mg/kg Single intravenous TNX-1500 doses tested

Follow-up duration 120 days Monitoring period after TNX-1500 dosing and KLH challenge

TDAR reduction at lowest dose ≈70% reduction Peak secondary KLH response vs placebo at 3 mg/kg

TNX-1500 half-life 10 mg/kg 37.8 days Mean terminal elimination half-life at 10 mg/kg

TNX-1500 half-life 30 mg/kg 33.8 days Mean terminal elimination half-life at 30 mg/kg

Planned Phase 2 kidney recipients 5 patients Investigator-initiated study at MGH, pending IND clearance

Phase 2 timing 2nd half of 2026 Expected start of MGH kidney transplant study, FDA-dependent

Key Terms

T cell-dependent antibody responses, Investigational New Drug, monoclonal antibody, treatment-emergent adverse event, +1 more

5 terms

T cell-dependent antibody responses medical

"to assess the primary and secondary T cell-dependent antibody responses ("TDAR")"

Investigational New Drug regulatory

"pending U.S. Food and Drug Administration (FDA) clearance of MGH’s Investigational New Drug (IND) application"

An investigational new drug is a medication that is still being tested in clinical trials to determine if it is safe and effective for treating a specific condition. For investors, it represents a potential breakthrough that could lead to a new treatment and significant financial gains if successful, but also carries risks since it has not yet been approved for widespread use.

monoclonal antibody medical

"TNX-1500, an Fc-Modified anti-CD154 Monoclonal Antibody"

A monoclonal antibody is a laboratory-made protein designed to recognize and attach to a specific target in the body, such as a disease-causing substance or cell. It functions like a highly precise lock-and-key tool, helping to treat or detect illnesses. For investors, companies developing monoclonal antibodies can represent promising opportunities in the healthcare sector, especially as these treatments often address unmet medical needs.

treatment-emergent adverse event medical

"The only treatment-emergent adverse event (TEAE) deemed possibly related to study drug was aphthous ulcer"

An event is called a treatment-emergent adverse event when a new or worsening unwanted health effect appears after a person starts a drug or medical treatment, typically measured from the first dose onward in clinical studies. Investors watch these events because they can stop or slow product approval, raise development costs, or undermine market confidence—like a widely reported defect in a new gadget that triggers recalls and damages sales.

xenograft rejection medical

"as well as prevention of xenograft rejection, preclinical studies"

Understanding 8-K Material Events →

05/27/2026 - 07:05 AM

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): May 27, 2026

TONIX PHARMACEUTICALS HOLDING CORP.

(Exact name of registrant as specified in its charter)

Nevada

001-36019

26-1434750

(State or Other Jurisdiction

of Incorporation)

(Commission

File Number)

(IRS Employer

Identification No.)

200 Connell Drive, Suite 3100, Berkeley Heights, New Jersey 07922

(Address of principal executive offices) (Zip Code)

Registrant’s telephone number, including area code: (862) 799-8599

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		TNXP		The NASDAQ Global Select 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 7.01

Regulation FD Disclosure.

On May 27, 2026, Tonix Pharmaceuticals Holding Corp. (the “Company”) announced the publication of a paper, “First-in-Human, Phase 1, Randomized, Double-Blind, Placebo-Controlled Study of TNX-1500, an Fc-Modified anti-CD154 Monoclonal Antibody, Evaluating the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Single-Ascending Doses in Healthy Adults,” in the peer-reviewed Journal of Clinical Immunology (the “Manuscript”). A copy of the press release that discussed this matter is attached hereto as Exhibit 99.01. A copy of the Manuscript is attached hereto as Exhibit 99.02.

The information in this Item 7.01 of this Current Report on Form 8-K, including Exhibits 99.01 and 99.02 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.

Item 8.01

Other Events.

On May 27, 2026, the Company announced the publication of the Manuscript, which reports findings from a single-center, first-in-human, Phase 1, randomized, double-blind, placebo-controlled, single-ascending dose escalation study in 26 healthy adult volunteers of the Company’s TNX-1500 product candidate, a monoclonal antibody in development for the prevention of organ transplant rejection and the treatment of autoimmune diseases. Participants were enrolled across three ascending dose cohorts (3, 10, and 30 mg/kg) or placebo and received a single intravenous infusion of TNX-1500 or placebo, followed by intramuscular injections of keyhole limpet hemocyanin (“KLH”) on days 2 and 29 to assess the primary and secondary T cell-dependent antibody responses (“TDAR”), and monitored over a 120-day follow-up period. TNX-1500 blocked the primary TDAR to KLH at all doses, blocked the secondary response at the 10 and 30 mg/kg doses, and reduced peak secondary response to KLH by approximately 70% relative to placebo at the 3 mg/kg dose.

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.

Item 9.01

Financial Statements and Exhibits.

(d)	Exhibit No.	Description.
	99.01	Press Release, date May 27, 2026
	99.02	First-in-Human, Phase 1, Randomized, Double-Blind, Placebo-Controlled Study of TNX-1500, an Fc-Modified anti-CD154 Monoclonal Antibody, Evaluating the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Single-Ascending Doses in Healthy Adults
	104	Cover Page Interactive Data File (embedded within the Inline XBRL document)

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.

	TONIX PHARMACEUTICALS HOLDING CORP.

Date: May 27, 2026	By:	/s/ Bradley Saenger
		Bradley Saenger
		Chief Financial Officer

Exhibit 99.01

Tonix Pharmaceuticals Announces Publication of Phase 1 Clinical Data of TNX-1500, an Fc-Modified anti-CD40L (CD154) Monoclonal Antibody, in the Peer-Reviewed Journal of Clinical Immunology

Phase 1 data support TNX-1500 as a potentially first-in-class, best-in-class, third-generation anti-CD40L monoclonal antibody for the prevention of kidney transplant rejection

Phase 2 investigator-initiated study in adult kidney transplant at Massachusetts General Hospital (MGH) expected to initiate in the 2^nd half of 2026 pending U.S. Food and Drug Administration (FDA) clearance of MGH’s Investigational New Drug (IND) application

BERKELEY HEIGHTS, N.J., May 27, 2026 (GLOBE NEWSWIRE) — Tonix Pharmaceuticals Holding Corp. (Nasdaq: TNXP) (“Tonix” or the “Company”), a fully integrated, commercial-stage biotechnology company, today announced the publication of a paper, “First-in-Human, Phase 1, Randomized, Double-Blind, Placebo-Controlled Study of TNX-1500, an Fc-Modified anti-CD154 Monoclonal Antibody, Evaluating the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Single-Ascending Doses in Healthy Adults,” in the peer-reviewed Journal of Clinical Immunology. TNX-1500 is an investigational, third-generation Fc-modified IgG4 anti-CD40L (also known as CD154) monoclonal antibody (mAb) in development for the prevention of organ transplant rejection and the treatment of autoimmune diseases. The manuscript can be accessed at https://pubmed.ncbi.nlm.nih.gov/42053701/.

“The CD40L is a validated target for preventing organ rejection in transplant and treating autoimmune disease, yet no anti-CD40L mAb has been approved for any indication,” said Seth Lederman, M.D., Chief Executive Officer of Tonix Pharmaceuticals. “TNX-1500 is a Phase 2 ready humanized mAb engineered to improve safety and tolerability relative to first-generation anti-CD40L mAbs, while preserving the durable half-life and certain effector functions associated with the Fc or crystallizable fragment. We believe the Phase 1 results show that these design objectives were achieved in TNX-1500.”

Dr. Gregory Sullivan, M.D., Chief Medical Officer of Tonix Pharmaceuticals added, “The Phase 1 study evaluated TNX-1500’s safety, tolerability, pharmacokinetics, and pharmacodynamics. TNX-1500 was generally well tolerated, demonstrated a favorable safety profile, suppressed the primary and secondary T cell-dependent antibody responses (TDARs) to keyhole limpet hemocyanin (KLH) antigen, and showed a half-life which supports monthly intravenous dosing. We expect a Phase 2, investigator-initiated study of TNX-1500 in the prevention of kidney allograft rejection at MGH to begin in the 2^nd half of 2026 pending clearance of the IND by the FDA.”

The publication reports findings from a single-center, first-in-human, Phase 1, randomized, double-blind, placebo-controlled, single-ascending dose escalation study in 26 healthy adult volunteers. Participants were enrolled across three ascending dose cohorts (3, 10, and 30 mg/kg) or placebo and received a single intravenous infusion of TNX-1500 or placebo, followed by intramuscular injections of KLH on days 2 and 29 to assess the TDAR, and monitored over a 120-day follow-up period. TNX-1500 blocked the primary T cell–dependent antibody response to KLH at all doses, blocked the secondary response at the 10 and 30 mg/kg doses, and reduced peak secondary response to KLH by ~70% relative to placebo at the 3 mg/kg dose.

TNX-1500 was generally well tolerated, with no serious adverse events, and no discontinuations due to adverse events. The only treatment-emergent adverse event (TEAE) deemed possibly related to study drug was aphthous ulcer, which occurred in 1 participant in each of the three TNX-1500 groups; all TEAEs were rated as mild and resolved in 2-10 days. No TEAEs were determined to be related to KLH administration. There were no administration or injection site reactions (one of the prespecified TEAEs of special interest). Pharmacokinetic analyses suggested approximately dose-proportional exposure across the 3 to 30 mg/kg range, with mean terminal elimination half-lives of 37.8 and 33.8 days at the 10 and 30 mg/kg dose levels, respectively. TNX-1500 at 10 and 30 mg/kg blocked the primary and secondary anti-KLH TDAR through day 120, and at 3 mg/kg reduced the peak secondary response by approximately 70% relative to placebo. Across all dose cohorts, TNX-1500 was associated with a rapid (less than one-hour post-dose) and sustained reduction in soluble CD40L (sCD154) over the 120-day study period.

About TNX-1500

TNX-1500 (Fc-modified humanized anti-CD40L mAb) is a Phase 2 ready, humanized monoclonal antibody that interacts with the CD40-ligand (CD40L), also known as CD154. TNX-1500 is being developed for the prevention of kidney transplant rejection and the treatment of autoimmune diseases. Anti-CD40L has multiple potential indications in addition to solid organ and bone marrow transplantation including autoimmune diseases. Collaborations are ongoing with MGH on allo-heart and -kidney transplantation in nonhuman primates, as well as prevention of xenograft rejection, preclinical studies, and prevention of allograft rejection in sensitized patients. The Phase 2 investigator-initiated study by MGH is expected to initiate enrollment in the 2^nd half of 2026, pending FDA clearance of the IND, to evaluate TNX-1500 in five kidney transplant recipients. The study is designed to assess the safety, tolerability, and activity of TNX-1500 in preventing kidney transplant rejection while decreasing the exposure to conventional immunosuppressive drugs, which are associated with infection, cancer, cardiovascular side effects, and various metabolic derangements with long term use.

Tonix Pharmaceuticals Holding Corp.

Tonix Pharmaceuticals* is a fully integrated, commercial-stage biotechnology company focused on central nervous system (CNS) disorders, infectious diseases, immunology conditions, and rare diseases where there exists high unmet medical need. TONMYA® (cyclobenzaprine HCl sublingual tablets 2.8mg), the Company’s flagship internally conceived and developed medicine, is the first new treatment for fibromyalgia in more than 15 years. Tonix’s CNS commercial infrastructure supports its marketed products, including its acute migraine products, Zembrace® SymTouch® (sumatriptan injection 3 mg) and Tosymra® (sumatriptan nasal spray 10 mg). Tonix is extending the science behind TONMYA in Phase 2 clinical studies to evaluate its potential in major depressive disorder and acute stress disorder/acute stress reaction. Tonix is also advancing a pipeline of infectious disease programs, including monoclonal antibody TNX-4800 (anti-OspA mAb) for Lyme disease prevention in the U.S. and TNX-801 (horsepox, live virus vaccine), a vaccine in development for the prevention of mpox and smallpox. Within immunology, Tonix is developing TNX-1500 (anti-CD40L mAb), a third-generation CD40 ligand inhibitor for the prevention of kidney transplant rejection. Finally, the Company’s rare disease portfolio includes TNX-2900, which is Phase 2 ready for the treatment of Prader-Willi syndrome. To learn more, visit www.tonixpharma.com.

*Tonix’s product development candidates are investigational new drugs or biologics; their efficacy and safety have not been established and have not been approved for any indication.

Zembrace SymTouch and Tosymra are registered trademarks of Tonix Medicines. TONMYA is a registered trademark of Tonix Pharma Limited. All other marks are property of their respective owners.

Forward Looking Statements

Certain statements in this press release are forward-looking within the meaning of the Private Securities Litigation Reform Act of 1995 including those relating to the completion of the offering, the satisfaction of customary closing conditions, the intended use of proceeds from the offering and other statements that are predictive in nature. These statements may be identified by the use of forward-looking words such as “anticipate,” “believe,” “forecast,” “estimate,” “expect,” and “intend,” among others. There are a number of factors that could cause actual events to differ materially from those indicated by such forward-looking statements. These factors include, but are not limited to, risks related to the failure to successfully launch and commercialize TONMYA^® and any of our approved products; risks related to the failure to obtain FDA clearances or approvals and noncompliance with FDA regulations; risks related to the timing and progress of clinical development of our product candidates; our need for additional financing; uncertainties of patent protection and litigation; uncertainties of government or third party payor reimbursement; limited research and development efforts and dependence upon third parties; and substantial competition. As with any pharmaceutical under development, there are significant risks in the development, regulatory approval and commercialization of new products. Tonix does not undertake an obligation to update or revise any forward-looking statement. Investors should read the risk factors set in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025, as filed with the SEC on March 12, 2026, and periodic reports filed with the SEC on or after the date thereof. Tonix does not undertake an obligation to update or revise any forward-looking statement. All of Tonix’s forward-looking statements are expressly qualified by all such risk factors and other cautionary statements. The information set forth herein speaks only as of the date thereof.

Investor Contacts

Jessica Morris

Tonix Pharmaceuticals

(862) 799-8599

investor.relations@tonixpharma.com

Brian Korb

astr partners

(917) 653-5122

brian.korb@astrpartners.com

Media Contacts

Deborah Elson

Tonix Pharmaceuticals

deborah.elson@tonixpharma.com

Ray Jordan

Putnam Insights

ray@putnaminsights.com

Exhibit 99.02

Source: View Original Filing on SEC EDGAR

FAQ

What did Tonix Pharmaceuticals (TNXP) announce about TNX-1500 in this 8-K filing?

Tonix announced publication of Phase 1 clinical data for TNX-1500 in the Journal of Clinical Immunology. The study showed the investigational antibody was generally well tolerated and suppressed T cell-dependent antibody responses to a KLH antigen in healthy volunteers over a 120-day follow-up period.

What were the key design features of the TNX-1500 Phase 1 study for TNXP?

The Phase 1 trial was a single-center, randomized, double-blind, placebo-controlled, single-ascending dose study in 26 healthy adults. Participants received one intravenous infusion of TNX-1500 at 3, 10, or 30 mg/kg or placebo, plus KLH injections on days 2 and 29, with 120 days of monitoring.

How did TNX-1500 perform on safety and tolerability in the Tonix Phase 1 trial?

TNX-1500 was generally well tolerated with no serious adverse events and no discontinuations due to adverse events. The only treatment-emergent event considered possibly related was mild aphthous ulcer in one participant per active-dose group, resolving within 2–10 days, and no administration-site reactions were observed.

What pharmacodynamic effects of TNX-1500 were reported by Tonix Pharmaceuticals?

TNX-1500 blocked the primary T cell-dependent antibody response to KLH at all dose levels. It also blocked the secondary response at 10 and 30 mg/kg and reduced the peak secondary response by about 70% versus placebo at 3 mg/kg, indicating robust target engagement over the 120-day study period.

What pharmacokinetic profile did TNX-1500 show in the Tonix Phase 1 study?

Pharmacokinetic analyses indicated approximately dose-proportional exposure across the 3–30 mg/kg range. Mean terminal elimination half-lives were 37.8 days at 10 mg/kg and 33.8 days at 30 mg/kg, supporting the potential for monthly intravenous dosing of TNX-1500 in future clinical studies.

What are the next clinical plans for TNX-1500 mentioned by Tonix (TNXP)?

Tonix expects an investigator-initiated Phase 2 study of TNX-1500 in preventing kidney transplant rejection at Massachusetts General Hospital to begin in the second half of 2026. This timing is contingent on U.S. Food and Drug Administration clearance of the hospital’s Investigational New Drug application for the program.

For which indications is Tonix developing TNX-1500 beyond kidney transplant rejection?

TNX-1500 targets CD40L and is being developed for preventing kidney transplant rejection and treating autoimmune diseases. Tonix also notes potential in solid organ and bone marrow transplantation, xenograft rejection, and sensitized patients, supported by ongoing collaborations with Massachusetts General Hospital in preclinical and translational studies.

Filing Exhibits & Attachments

41 documents

Tonix Pharmaceuticals (Nasdaq: TNXP) details TNX-1500 Phase 1 results and kidney transplant Phase 2 plan

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