Antigen p64K hVEGFKDR adjuvant NAcGM3 VSSP(Centro de Ingenieria Genetica y Biotecnologia)

CIGB-247, a VSSP-adjuvanted VEGF-based vaccine, was evaluated in a phase I clinical trial in patients with advanced solid tumors (CENTAURO). Vaccination with the maximum dose of antigen showed an excellent safety profile, exhibited the highest immunogenicity and was the only one showing a reduction on platelet VEGF bioavailability. However, this antigen dose level did not achieve a complete seroconversion rate in vaccinated patients. These clinical results led us to the question whether a "reserve" of untapped immune response potential against VEGF could exist in cancer patients. To address this matter, CENTAURO-2 clinical trial was conducted where antigen and VSSP dose scale up were studied, and also incorporated the exploration of aluminum phosphate as adjuvant. These changes were made with the aim to increase immune response against VEGF.

The present study reports the characterization of the humoral response elicited by CIGB-247 from the combining of different antigen doses and adjuvants. Cancer patients were immunologically monitored for approximately 1 year. Vaccination with different CIGB-247 formulations exhibited a very positive safety profile. Cancer patients developed IgM, IgG or IgA antibodies specific to VEGF. Elicited polyclonal antibodies had the ability to block the interaction between VEGF and its receptors, VEGFR1 and VEGFR2. The highest humoral response was detected in patients immunized with 800 μg of antigen + 200 μg of VSSP. Off-protocol long-term vaccination did not produce negative changes in humoral response.

Vaccination with a human VEGF variant molecule as antigen in combination with VSSP or aluminum phosphate is immunogenic. The results of this study could contribute to the investigation of this vaccine therapy in an adequately powered efficacy trial.

Trial registration number: RPCEC00000155. Cuban Public Clinical Trial Registry. Date of registration: June 06, 2013. Available from: http://registroclinico.sld.cu/ .

CIGB 247 is a novel cancer therapeutic vaccine based on human vascular endothelial growth factor (VEGF) variant molecule as antigen, in combination with a bacterial adjuvant. This vaccine candidate has previously demonstrated efficacy and safety in mice, rats, rabbits and non-human primates. In the present study we evaluated the effects on the clinical, hematological and biochemical parameters of CIGB 247 vaccine in Chlorocebus aethiops monkeys. Three groups of monkeys were immunized with three doses of vaccine formulation to measure physiological values of clinical, hematological and serum biochemical parameters. Monkeys' body weight and temperature were kept stable and close to standard values throughout the study. Variations in the levels of red blood cells and hemoglobin were observed among the different groups for all injected doses, but these hematological parameters recovered normal values at the end of the study. On the other hand, biochemical parameters such as the total bilirubin and total protein counts showed variations along the study, while they were not associated with the test substance. In summary, no negative effects on clinical, hematological and biochemical parameters were detected. Together, our results put forward the potential and support the safety of the CIGB 247 vaccine candidate for use in clinical applications. The data presented here can be used to estimate a human dosing regimen from preclinical data.