Specific active immunotherapy with the HEBERSaVax VEGF-based cancer vaccine: From bench to bedside

BioHabana 2022: Preventive and Immunotherapeutic Strategies Against COVID-19 and Cancer in Cuba

The convergence of life sciences with neurosciences, nanotechnology, data management, and engineering has caused a technological diversification of the biotechnology, pharmaceutical, and medical technology industries, including the phenomenon of digital transformation, which has given rise to the so-called Fourth Industrial Revolution (Industry 4.0). Confronting the COVID-19 pandemic revealed the outstanding response capacity of the scientific community and the biopharmaceutical industry, based on a multidisciplinary and interinstitutional approach that has achieved an unprecedented integration in the history of biomedical science. Cuba, a small country, with scarce material resources, has had remarkable success in controlling the disease, which also highlights the impact of social factors. This report presents a summary of the most relevant presentations of selected topics during the scientific meeting, "BioHabana 2022: Cancer Immunotherapy and the COVID-19 Pandemic," which was held in Havana Cuba in April 2022.

Polyclonal antibody-induced downregulation of HER1/EGFR and HER2 surpasses the effect of combinations of specific registered antibodies

Background

Antitumor therapies targeting HER1/EGFR and HER2, such as monoclonal antibodies (MAbs) and tyrosine-kinase inhibitors (TKIs), have demonstrated a significant clinical benefit, but the emergence of resistance limits long-term efficacy. While secondary HER1 mutations confer tolerance to TKI, compensatory upregulation of HER2 drives resistance to anti-HER1 MAbs, which identifies MAb combinations targeting both receptors as an attractive therapeutic strategy. Nevertheless, toxicity hampers the clinical validation of this approach. Alternatively, cancer vaccines may induce antibodies directed against several antigens with less concern about induced toxicity.

Methods

Polyclonal antibodies (PAbs) targeting HER1 and HER2 were induced in mice or rabbits through immunization. Recognition of different epitopes on targets by PAbs was validated by phage-display technology. Receptor downregulation was evaluated by flow cytometry, immunofluorescence, and Western blot. MTT assays assessed cytotoxicity, while the antitumor effect of PAbs was assayed in nude mice.

Results

PAbs promoted degradation of HER1 and HER2 regarding clinical MAbs or their combinations. As a result, inhibition of cytotoxicity on tumor cell lines was improved, even in the presence of oncogenic mutations in HER1, as well as in cetuximab-insensitive cells. Accordingly, the antitumor effect of vaccination-induced PAbs was observed in lung tumor lines representative of sensitivity or resistance to HER1 targeting therapies.

Conclusions

Immunization against HER1 and HER2 receptors offers an alternative to passive administration of combinations of MAbs, since vaccination-induced PAbs promote the downregulation of both receptors and they have a higher impact on the survival of tumor cells.

Enhanced performance of an electrochemical aptasensor for real-time detection of vascular endothelial growth factor (VEGF) by nanofabrication and ratiometric measurement

Achieving a biosensing interface without baseline drift caused by variables in matrix samples is essential for real-time detection of analytes. In this study, we developed a molecular beacon based electrochemical aptasensor to realize the ratiometric signal quantification of VEGF in serum by surface modification of nanocomposites of graphene oxide/methylene blue (GO/MB) and AuNPs followed by the attachment of ferrocene-labeled aptamer (aptamer-Fc) against VEGF. The presence of VEGF can trigger the configuration change of aptamer-Fc, resulting in the redox probe Fc being far away from the electrode surface to attenuate the electrochemical communication between electrode and Fc. Meanwhile, signal of MB also decreased due to the impediment of aptamer-Fc to electron transfer passage. The achieved GC-rGO/MB-AuNPs-aptamer-Fc sensing interface was successfully used for the sensitive detection of VEGF in real-time with a linear detection range 2-500 pg mL^-1 and detection limit of 0.1 pg mL^-1 based on ratiometric dual signal (Fc and MB) read-out. It was observed loading MB and AuNPs to the GO based sensing interface was favorable to enhance the analytical performance in terms of sensitivity and capability to effectively eliminate background interference. This electrochemical aptasensor provides a universal and reliable biosensing platform which is potential for real-time and sensitive tracking of various cytokines in vivo.

Specific humoral response in cancer patients treated with a VEGF-specific active immunotherapy procedure within a compassionate use program

BACKGROUND

CIGB-247 is a cancer therapeutic vaccine that uses as antigen a variant of human vascular endothelial growth factor (VEGF) mixed with the bacterially-derived adjuvant VSSP. CIGB-247 has been already evaluated in two phase I clinical trials (CENTAURO and CENTAURO-2), showing to be safe and immunogenic in advanced cancer patients selected under well-defined and controlled clinical conditions. Surviving patients were submitted to monthly re-immunizations and some of them showed objective clinical benefits. Based on these results, a compassionate use program (CUP) with CIGB-247 was initiated for patients that did not meet the strict entry criteria applied for the CENTAURO and CENTAURO-2 clinical trials, but could potentially benefit from the application of this cancer therapeutic vaccine.

RESULTS

Polyclonal IgM, IgA and IgG antibodies specific for VEGF were detected by ELISA in serum samples from patients vaccinated with 400 μg of antigen combined with 200 μg of VSSP. Polyclonal antibody response showed no cross reactivity for other VEGF family member molecules like VEGF-C and VEGF-D. Serum from immunized individuals was able to block the binding of VEGF to its receptors VEGFR2 and VEGFR1. IgG fraction purified from immune sera shared the aforementioned characteristics and also inhibited the interaction between VEGF and the therapeutic recombinant antibody bevacizumab, an anti-angiogenic drug approved for the treatment of different tumors. No serious adverse events attributable to CIGB-247 have been documented yet in participants of the CIGB-247 CUP. The present paper is a first report of our findings concerning the humoral response and safety characteristics in treated CIGB-247 CUP cancer patients. The study has provided the unique opportunity of not only testing CIGB-247 in a broader clinical spectrum sample of Cuban cancer patients, but also within the context of the day-to-day clinical practice and treatment settings for these diseases in Cuban medical institutions.

CONCLUSIONS

The CIGB-247 CUP has demonstrated that immunization and follow-up of a variety of cancer patients, under day-to-day clinical practice conditions in several Cuban medical institutions, replicate our previous findings in clinical trials: CIGB-247 is safe and immunogenic.