Longitudinal Assessment of an 800 µg Dose of HEBERSaVax in Non-Human Primates over Six Months

Background/Objectives: HEBERSaVax is a therapeutic cancer vaccine based on recombinant human VEGF antigen adjuvated with VSSP or Aluminum Phosphate (AP). Clinical trials demonstrated the vaccine’s safety and tolerability, with predominantly mild to moderate (grade 1–2) local adverse events. Initial dose optimization studies using the VSSP (Center of Molecular Immunology (CIM), Havana, Cuba) adjuvant showed that increasing the antigen dose to 800 μg significantly enhanced immunogenicity, as measured by improved seroconversion rates, stronger blockade of VEGF/VEGFR1-2 interactions, and reduced platelet-derived VEGF levels. Methods: The AP adjuvant was used to perform essential preclinical validation in non-human primates to support the transition of the 800 μg antigen dose to Phase II clinical trials (CENTAURO-4 and CENTAURO-6). Results: HEBERSaVax adjuvated with AP induced: (1) robust humoral responses with high-titer anti-VEGF antibodies (peak 1:15,000), (2) functional biological activity, specifically the suppression of VEGF-mediated signal transduction, in 90% (9/10 animals), and (3) measurable cellular immune responses. All immunogenic effects were achieved without evidence of systemic toxicity, confirming the safety profile of this preparation. Conclusions: These findings provide compelling preclinical evidence that the 800 μg HEBERSaVax/AP combination maintains the immunogenic potential previously observed with VSSP while demonstrating an equally favorable safety profile. The results strongly support continued clinical development of this VEGF-targeted immunotherapy for cancer treatment.