Anti-EGF antibodies as surrogate biomarkers of clinical efficacy in stage IIIB/IV non-small-cell lung cancer patients treated with an optimized CIMAvax-EGF vaccination schedule

ABSTRACT

We previously reported that CIMAvax-EGF vaccine is safe, immunogenic and efficacious to treat advanced non-small-cell lung cancer (NSCLC) patients. A phase III trial was designed using an optimized immunization schedule. It included higher antigen dose and injections at multiple sites. Immune response and circulating biomarkers were studied in a subset of patients. EGF-specific antibody titers, IgG subclasses, peptide immunodominance and circulating biomarkers were assessed by ELISA. In vitro EGF-neutralization capacity of immune sera and EGF-IgG binding kinetics was evaluated by Western Blot and Surface Plasmon Resonance (SPR) technology, respectively. We show that CIMAvax-EGF elicited mainly IgG3/IgG4 antibodies at titers exceeding 1:4000 in 80% of vaccinated patients after 3 months of treatment. The EGF-specific humoral response was directed against the central region of the EGF molecule. For the first time, the kinetic constants of EGF-specific antibodies were measured evidencing affinity maturation of antibody repertoire up to month 12 of vaccination. Notably, the capacity of post-immune sera to inhibit EGFR phosphorylation significantly increased during the course of the immunization scheme and was related to clinical outcome (P = .013, log-rank test). Basal concentrations of EGF and TGFα in the serum were affected by EGF-based immunization. In conclusion, the CIMAvax-EGF vaccine induces an EGF-specific protective humoral response in a high percent of NSCLC vaccinated patients, the quantity and quality of which were associated with clinical benefit (clinical trial registration number: RPCEC00000161, http://registroclinico.sld.cu/).

Abbreviations

EGF: epidermal growth factor; EGFR: epidermal growth factor receptor; Ab: antibody; AR: amphiregulin; NSCLC: non-small-cell lung cancer; rhEGF: recombinant human epidermal growth factor; BSC: best supportive care; TGFα: tumor growth factor alpha; IL-8: interleukin 8; MAb: monoclonal antibody; SPR: surface plasmon resonance

KEYWORDS:

• NSCLC
• cancer vaccine
• surrogate biomarker
• EGF
• antibodies affinity

Acknowledgments

This study was conducted by the Center of Molecular Immunology in Havana, Cuba. We are especially grateful to the participating patients and their families, as well as the staffs of all institutions involved in this study.

Disclosure of Potential Conflicts of Interest

BG, KPF, CEV, PCR, ZG, AG, TC and ZM are employees of the Center of Molecular Immunology, which sponsored all the clinical studies and produced CIMAvax-EGF. The rest of the authors have no conflict of interest. No consulting fees or payments for speeches or appearances have been received by any of the authors.

Author’s contributions

Conception and design: X. Popa and B. García

Clinical investigators (recruited and treated patients): E. Neninger

Immunological assessments: X. Popa, K. P. Fuentes, Z. Gonzalez and A. Gonzalez

SPR measurements and analysis: K. Alvarez and V. Huerta

Trial conduction and supervision: P.C. Rodriguez, T. Crombet and E. Neninger

Writing and or/revision of the manuscript: X. Popa, B. García, T. Crombet and Z. Mazorra

Analysis and interpretation of data: X. Popa, B. Garcia, C. E. Viada and Z. Mazorra

Additional information

Funding

This study was supported by the Center of Molecular Immunology (https://www.cim.cu/es).