HER1-ECD vaccination dispenses with emulsification to elicit HER1-specific anti-proliferative effects.

EGFR (HER1) highlights as one of the most relevant tumor associated antigen in epithelial malignant cells. Monoclonal antibodies and tyrosine kinase inhibitors against EGFR remain as the most advanced approaches in clinical trials. More recently, an active immunotherapy using the HER1 extracellular domain (ECD) adjuvated in very small size proteoliposomes (VSSP) and emulsified in Montanide ISA-51 demonstrated its strength to inhibit tumor cell line proliferation by arresting cells in G(0)/G(1) stage and induction of apoptosis. In this study, we present a simpler HER1-ECD-based formulation, which is lacking the oily component Montanide ISA-51. Generated antibodies following non-emulsive formulation immunization recognized membrane EGFR; avoid EGF and TGFalpha coupling to EGFR leading to a marked abrogation of EGFR phosphorylation levels. Non-emulsive formulation also arrests cell cycle in G(0)/G(1) stage, demonstrating it preserves previous formulation quality in a newer and simpler formulation.

Anti-EGFR activation, anti-proliferative and pro-apoptotic effects of polyclonal antibodies induced by EGFR-based cancer vaccine.

Up to now clinical experiences focusing EGF receptor, an attractive target for cancer therapy, have been limited to passive therapies, suggesting that therapeutic cancer vaccines inducing anti-epidermal growth factor receptor (EGFR) antibodies could also work. Here, the humoral immune response induced in mice with a vaccine formulation containing the human EGFR-extracellular domain and very small-sized proteoliposomes (VSSP), a novel nanoparticulated adjuvant was assessed. In vaccinated mice sera average of the specific polyclonal antibodies (PAb) titers was 10(-5). Anti-EGFR PAb were able to bind EGFR+ tumor cell lines, expressing different levels of the molecule. Noteworthy, the presence of Cetuximab only partially inhibited the vaccine-induced antibodies binding to H125 cells. Anti-EGFR PAb abrogated ligands-dependent EGFR phosphorylation, provoking tumor cells apoptosis. The described EGFR-based vaccine might be a superior therapeutic approach for patients with EGFR+ tumors.

Active antimetastatic immunotherapy in Lewis lung carcinoma with self EGFR extracellular domain protein in VSSP adjuvant.

The epidermal growth factor receptor (EGFR) plays a central role in regulating neoplastic processes. The EGFR overexpression in many human epithelial tumors has been correlated with disease progression and bad prognosis. Passive EGFR-directed immunotherapy, but not active specific approaches, has already been introduced in medical oncology practice. Then we wonder if mice immunization with the extracellular domain of murine EGFR (mEGFR-ECD) in adjuvants can circumvent tolerance to self EGFR, by inducing an immune response with consequent antitumor effect. The present study demonstrated that despite mEGFR expression in thymus, strong DTH response was induced by inoculation of mice with the mEGFR-ECD. This self-immunization, using both CFA and very small sized proteoliposomes from Neisseria meningitidis (VSSP), promoted highly specific IgG titers, predominantly IgG2a and IgG2b. Sera from mice immunized with mEGFR-ECD/VSSP not only recognized EGFR+ tumor cell lines by FACS, but also inhibited their in vitro growth, even in the absence of complement. Noteworthy, vaccination of mice with mEGFR-ECD/VSSP stimulated a potent antimetastatic effect in the EGFR+ Lewis lung carcinoma model, while reproduction-associated side effects were absent. Curiously, mice immunized with the human EGFR-ECD (Her1-ECD) in VSSP though induced highly specific IgG antibodies with strong in vitro cytotoxic effect over EGFR+ human cell lines, showed low cross-reactivity with the mEGFR-ECD. These results further encouraged the development of the Her1-ECD/VSSP vaccine project for patients with EGFR+ tumors.