GeoVax Labs, Inc. announced publication of interim Phase 2 clinical data showing its next-generation COVID-19 vaccine, GEO-CM04S1, generated significantly stronger and more durable SARS-CoV-2-specific T-cell responses than BNT162b2 in patients with chronic lymphocytic leukemia. The findings, published in the British Journal of Haematology, reveal that 40% of GEO-CM04S1 recipients met the primary immunologic endpoint compared to 14.3% for the mRNA vaccine, leading the Data and Safety Monitoring Board to discontinue the comparator arm and proceed exclusively with GEO-CM04S1.
The trial's significance lies in addressing a critical unmet medical need for immunocompromised populations who respond poorly to first-generation COVID-19 vaccines. More than 40 million adults in the U.S. and 400 million globally have compromised immunity, with many failing to mount meaningful responses to currently authorized vaccines. CLL patients represent a particularly vulnerable group due to their impaired ability to generate humoral immune responses, making T-cell mediated immunity crucial for protection.
GEO-CM04S1's dual-antigen design, targeting both spike and nucleocapsid proteins through an MVA-based platform, demonstrated approximately 10-fold higher nucleocapsid-specific CD4 T-cell activation compared to BNT162b2, with responses maintained through Day 180. The vaccine also generated sustained nucleocapsid-specific antibodies and showed correlation between these antibodies and T-cell activation, indicating broader immune engagement despite CLL-associated humoral defects.
Kelly T. McKee, MD, MPH, Chief Medical Officer, stated the results demonstrate GEO-CM04S1's ability to address immune limitations in CLL patients by inducing strong, durable T-cell responses. The DSMB's decision to discontinue the comparator arm further validates the vaccine's clinical relevance for immunocompromised individuals. David Dodd, Chairman & CEO, emphasized that GEO-CM04S1 represents a purpose-built solution for high-risk patients lacking durable protection from first-generation vaccines.
The medical implications extend beyond CLL patients to include other immunocompromised populations such as CAR-T and stem-cell transplant recipients, who typically respond poorly to current vaccines. The multi-antigen design appears to stimulate more durable and variant-resilient immune responses than single-antigen mRNA approaches, potentially offering longer-lasting protection against evolving SARS-CoV-2 variants.
Commercial significance is substantial, with immunocompromised patient segments representing a $30 billion-plus annual potential market. The peer-reviewed publication strengthens GeoVax's regulatory and partnering strategy as the company advances toward potential commercialization. For more information about the company's clinical trials and updates, visit their website at https://www.geovax.com.
The Phase 2 study enrolled 31 CLL patients previously vaccinated with mRNA vaccines, with 27 evaluable for primary analysis. No Grade 3 or higher adverse events were reported, indicating favorable safety profile. The trial continues as a single-arm study following the DSMB's decision, with GEO-CM04S1 being evaluated in multiple Phase 2 trials including as a primary vaccine for immunocompromised individuals and as a booster for CLL patients.
