EQS-News: GeoVax Announces British Journal of Haematology Publication Highlighting Superior T-Cell Responses of GEO-CM04S1 in CLL Patients

DSMB Ends Comparator Arm; Trial Proceeds Exclusively With GEO-CM04S1 Following mRNA Vaccine’s Failure to Meet Primary Endpoint

Phase 2 Data Reinforce GEO-CM04S1 as an Important Next-generation Vaccine Candidate for the 40 Million U.S. and 400 Million Global Immunocompromised Patients Underserved by First-generation COVID-19 Vaccines

ATLANTA, GA - December 15, 2025 (NEWMEDIAWIRE) - GeoVax Labs, Inc. (Nasdaq: GOVX), a clinical-stage biotechnology company developing multi-antigen vaccines and immunotherapies, today announced the publication of interim Phase 2 clinical data on its next-generation COVID-19 vaccine in patients with chronic lymphocytic leukemia (CLL).  

The Research Letter in the British Journal of Haematology reports that GEO-CM04S1 met the study’s primary immunologic endpoint, generating significantly stronger and more durable SARS-CoV-2–specific T-cell responses than BNT162b2 (Pfizer-BioNTech) in patients with chronic lymphocytic leukemia (CLL) - a population known for poor vaccine responsiveness.

Importantly, following interim analysis, the trial’s Data and Safety Monitoring Board (DSMB) ruled to discontinue the randomized, double-blind comparator arm after the mRNA vaccine failed to meet the predefined primary immunogenicity endpoint. Enrollment is now proceeding exclusively in a single-arm cohort receiving GEO-CM04S1, as previously described in GeoVax’s clinical update at the European Hematology Association (EHA) 2025 Conference.

GEO-CM04S1’s superior performance in enhancing cellular immune response against SARS-CoV-2 in individuals with CLL, a patient population that generally responds sub optimally to vaccines designed to induce humoral (antibody) responses, underscores its potential to fill a protection gap for profoundly immunocompromised patients. More than 40 million adults in the U.S. and 400 million globally have some degree of compromised immunity, many of whom fail to mount meaningful responses to currently authorized COVID-19 vaccines. GEO-CM04S1 is specifically designed to address this gap through its dual-antigen (Spike + Nucleocapsid), MVA-based platform, which promotes robust, durable T-cell responses that are less impacted by immune dysfunction and viral variation.

Phase 2 Study Overview (NCT05672355)

• CLL patients previously vaccinated with mRNA vaccines
• 31 enrolled; 27 evaluable for primary analysis
• Primary endpoint: greater than or equal to 3-fold rise in antigen-specific IFN-y-secreting T cells at Day 56
• Assessments: T-cell responses, binding/neutralizing antibodies, safety
• No Grade greater than or equal to 3 adverse events reported

Key Findings Published in BJH

1. GEO-CM04S1 achieved superior T-cell responses

• 40% of GEO-CM04S1 recipients met the primary endpoint vs. 14.3% for BNT162b2
• Higher Spike-specific IFN-y responses at Days 28, 56, and 84

2. Durable activation of Nucleocapsid-specific T cells

• Approximately 10-fold higher N-specific CD4 T-cell activation vs. BNT162b2
• Responses maintained through Day 180

3. Broader immune engagement in spite of CLL-associated humoral defects

• GEO-CM04S1 generated sustained N-IgG and a correlation between N-specific antibodies and T-cell activation
• mRNA vaccination produced higher early RBD-IgG titers but limited cellular immunity

Kelly T. McKee, MD, MPH, Chief Medical Officer, stated: “These results demonstrate GEO-CM04S1’s ability to address the immune limitations of CLL patients by inducing strong, durable T-cell responses to both spike and nucleocapsid proteins of SARS-CoV-2. The DSMB’s decision to discontinue the comparator arm further validates the vaccine’s clinical relevance for immunocompromised individuals.”

David Dodd, Chairman & CEO, added: “With more than 40 million immunocompromised Americans, many of whom lack durable protection from first-generation vaccines, GEO-CM04S1 represents a purpose-built solution for high-risk patients. This peer-reviewed publication strengthens our regulatory and partnering strategy as we advance toward potential commercialization.”

Medical and Commercial Significance

The findings published in BJH, combined with the DSMB’s action, reinforce the value of the differentiated profile of GEO-CM04S1 across multiple dimensions:

1. Critical unmet need: Immunocompromised individuals remain vulnerable and, in many cases, sub optimally protected from the threat of SARS-CoV-2.
2. Multi-antigen design: GEO-CM04S1’s dual-antigen design stimulates immune responses that appear to be more durable and variant-resilient than single-antigen mRNA approaches.
3. These segments represent a $30B+ annual potential commercial market.

About GEO-CM04S1

GEO-CM04S1 is a dual-antigen MVA-vectored COVID-19 vaccine being evaluated in multiple Phase 2 trials, including a primary vaccination for immunocompromised individuals, and a booster vaccination for CLL patients.

The vaccine has generated robust immune responses in difficult-to-vaccinate populations including CAR-T and stem-cell transplant recipients, who typically fail to respond well to first-generation vaccines.

About GeoVax

GeoVax Labs, Inc. is a clinical-stage biotechnology company developing novel vaccines against infectious diseases and therapies for solid tumor cancers. The Company’s lead clinical program is GEO-CM04S1, a next-generation COVID-19 vaccine currently in three Phase 2 clinical trials, being evaluated as (1) a primary vaccine for immunocompromised patients such as those suffering from hematologic cancers and other patient populations for whom the current authorized COVID-19 vaccines are insufficient, (2) a booster vaccine in patients with chronic lymphocytic leukemia (CLL) and (3) a more robust, durable COVID-19 booster among healthy patients who previously received the mRNA vaccines. In oncology the lead clinical program is evaluating a novel oncolytic solid tumor gene-directed therapy, Gedeptin®, having recently completed a multicenter Phase 1/2 clinical trial for advanced head and neck cancers. GeoVax is also developing a vaccine targeting Mpox and smallpox and, based on recent EMA regulatory guidance, anticipates progressing directly to a Phase 3 clinical evaluation, omitting Phase 1 and Phase 2 trials. GeoVax has a strong IP portfolio in support of its technologies and product candidates, holding worldwide rights for its technologies and products. For more information about the current status of our clinical trials and other updates, visit our website: www.geovax.com.

Forward-Looking Statements

This release contains forward-looking statements regarding GeoVax’s business plans. The words “believe,” “look forward to,” “may,” “estimate,” “continue,” “anticipate,” “intend,” “should,” “plan,” “could,” “target,” “potential,” “is likely,” “will,” “expect” and similar expressions, as they relate to us, are intended to identify forward-looking statements. We have based these forward-looking statements largely on our current expectations and projections about future events and financial trends that we believe may affect our financial condition, results of operations, business strategy and financial needs. Actual results may differ materially from those included in these statements due to a variety of factors, including whether: GeoVax is able to obtain acceptable results from ongoing or future clinical trials of its investigational products, GeoVax’s immuno-oncology products and preventative vaccines can provoke the desired responses, and those products or vaccines can be used effectively, GeoVax’s viral vector technology adequately amplifies immune responses to cancer antigens, GeoVax can develop and manufacture its immuno-oncology products and preventative vaccines with the desired characteristics in a timely manner, GeoVax’s immuno-oncology products and preventative vaccines will be safe for human use, GeoVax’s vaccines will effectively prevent targeted infections in humans, GeoVax’s immuno-oncology products and preventative vaccines will receive regulatory approvals necessary to be licensed and marketed, GeoVax raises required capital to complete development, there is development of competitive products that may be more effective or easier to use than GeoVax’s products, GeoVax will be able to enter into favorable manufacturing and distribution agreements, and other factors, over which GeoVax has no control.

Further information on our risk factors is contained in our periodic reports on Form 10-Q and Form 10-K that we have filed and will file with the SEC. Any forward-looking statement made by us herein speaks only as of the date on which it is made. Factors or events that could cause our actual results to differ may emerge from time to time, and it is not possible for us to predict all of them. We undertake no obligation to publicly update any forward-looking statement, whether as a result of new information, future developments or otherwise, except as may be required by law.

Company Contact:
info@geovax.com
678-384-7220 

Media Contact:
Jessica Starman
media@geovax.com 

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