Impact on antitumor response using a new adjuvant preparation as a component of a human papillomavirus type 16 therapeutic vaccine candidate.

Cervical cancer is a global public health problem and human papillomavirus (HPV) 16 accounts for approximately 50% of cases worldwide. Although there are several types of HPV therapeutic vaccines in clinical research, there are currently not approved for use in humans. We developed the fusion protein LALF32-51-E7 (hereafter denominated CIGB550-E7) defined by a cell-penetrating peptide linked to an E7 mutein for the treatment of HPV16-associated tumors. We have demonstrated previously the benefit on antitumor response induced by the immunization with CIGB550-E7 admixed with very small size proteoliposomes (VSSP) adjuvant compared with the adjuvant-free immunization. In this study, we obtained a similar antitumor response in mice immunized with CIGB550-E7 admixed with the new adjuvant sVSSP that does not contain any animal-derived product. Also, the immunization with the above mentioned vaccine preparation induced a cell-mediated immune response. Our results are encouraging for the future clinical trials with the vaccine candidate CIGB550-E7+sVSSP.

LALF32-51-E7 therapeutic vaccine induces antitumor immunity against human papillomavirus type 16 E7-expressing murine tumor metastases in the lungs.

One important goal of cancer immunotherapy is to prevent and treat tumor metastasis. We have previously reported the significant antitumor effect induced by the immunization with our human papillomavirus therapeutic protein-based vaccine (LALF32-51-E7) without adjuvant and admixed with clinically relevant adjuvants in the subcutaneous TC-1 tumor challenge model. In the present study, we evaluated the efficacy of the above mentioned vaccine formulations in controlling the hematogenous spread of TC-1 tumor cells using a more tumourigenic clone named TC-1* and other intravenous injection site less stressful than the tail vein. We generated a lung metastasis model by injecting TC-1* cells into the retro-orbital venous sinus and this is the first study describing it. Also, this is the first study that demonstrates the efficacy of the immunization with LALF32-51-E7 without adjuvant and admixed with VSSP or Al(OH)3 in controlling metastatic tumors increasing the survival of the mice. Our TC-1 lung metastasis model can be used to test the efficacy of other immunotherapeutic strategies based on E6/E7 antigens.

Expression, purification and characterization of a recombinant fusion protein based on the human papillomavirus-16 E7 antigen.

A fusion protein comprising a cell penetrating and immunostimulatory peptide corresponding to residues 32 to 51 of the Limulus polyphemus protein linked to human papillomavirus (HPV)-16 E7 antigen (LALF32-51-E7) was expressed in E. coli BL21 (DE3) cells. The recombinant protein in E. coli accounted for approximately 18% of the total cellular protein and purified with a single affinity chromatographic step. Yields of approximately 38 mg purified LALF32-51-E7 per liter of induced culture was obtained with an overall 52% recovery and constitutes a promising setting for the future production and scaling-up. Purified protein was characterized as soluble aggregates with molecular weight larger than 670 kDa, which is considered an important property to increase the immunogenicity of an antigen preparation. The recombinant fusion protein LALF32-51-E7 will be a promising vaccine candidate for the treatment of HPV-16 related malignancies.

Safety and Immunogenicity of a Human Papillomavirus Peptide Vaccine (CIGB-228) in Women with High-Grade Cervical Intraepithelial Neoplasia: First-in-Human, Proof-of-Concept Trial.

Objective. CIGB-228 is a novel therapeutic vaccine consisting of HLA-restricted HPV16 E7 epitope adjuvated with VSSP. This trial was designed to evaluate the toxicity, safety, immunogenicity, HPV clearance, and lesion regression. Methods. Seven women were entered. All were HLA-A2 positive, had biopsy-proven high-grade CIN, histologically positive for HPV16, and beared persistent postbiopsy lesions visible by digital colposcopy. HLA-A2 women with biopsy-proven high-grade CIN, HPV16-positive, and beared persistent postbiopsy lesions visible by digital colposcopy were vaccinated. One weekly injections of CIGB-228 vaccine was given for four weeks. Then, loop electrosurgical excision procedure (LEEP) of the transformation zone was performed. Study subjects were followed for 1 year after LEEP. Results. No toxicity beyond grade 1 was observed during and after the four vaccinations. Five of seven women had complete and partial regression. Cellular immune response was seen in all patients. HPV was cleared in three of the patients with complete response. Conclusion. CIGB-228 vaccination was well tolerated and capable to induce IFNγ-associated T-cell response in women with high-grade CIN. In several patients, lesion regression and HPV clearance were observed.

A novel fusion protein-based vaccine comprising a cell penetrating and immunostimulatory peptide linked to human papillomavirus (HPV) type 16 E7 antigen generates potent immunologic and anti-tumor responses in mice.

The ultimate success of cancer vaccination is dependent upon the generation of tumor-specific CTLs. In this study, we designed and evaluated a novel fusion protein comprising a cell penetrating and immunostimulatory peptide corresponding to residues 32-51 of the Limulus polyphemus protein (LALF(32-51)) linked to human papillomavirus (HPV) 16 E7 antigen (LALF(32-51)-E7). We demonstrated that LALF(32-51) penetrates the cell membrane and delivers E7 into cells. In a preclinical model of HPV16-induced cervical carcinoma we showed that vaccination with adjuvant-free LALF(32-51)-E7 fusion protein significantly improves the presentation of E7-derived peptides to T-cells in vitro and induces suppression of tumor growth.

Safety and Immunogenicity of a Human Papillomavirus Peptide Vaccine (CIGB-228) in Women with High-Grade Cervical Intraepithelial Neoplasia: First-in-Human, Proof-of-Concept Trial

Objective. CIGB-228 is a novel therapeutic vaccine consisting of HLA-restricted HPV16 E7 epitope adjuvated with VSSP. This trial was designed to evaluate the toxicity, safety, immunogenicity, HPV clearance, and lesion regression. Methods. Seven women were entered. All were HLA-A2 positive, had biopsy-proven high-grade CIN, histologically positive for HPV16, and beared persistent postbiopsy lesions visible by digital colposcopy. HLA-A2 women with biopsy-proven high-grade CIN, HPV16-positive, and beared persistent postbiopsy lesions visible by digital colposcopy were vaccinated. One weekly injections of CIGB-228 vaccine was given for four weeks. Then, loop electrosurgical excision procedure (LEEP) of the transformation zone was performed. Study subjects were followed for 1 year after LEEP. Results. No toxicity beyond grade 1 was observed during and after the four vaccinations. Five of seven women had complete and partial regression. Cellular immune response was seen in all patients. HPV was cleared in three of the patients with complete response. Conclusion. CIGB-228 vaccination was well tolerated and capable to induce IFN𝛾-associated T-cell response in women with high-grade CIN. In several patients, lesion regression and HPV clearance were observed(AU)

Immunotherapy with CTL peptide and VSSP eradicated established human papillomavirus (HPV) type 16 E7-expressing tumors.

Peptide-based vaccines aimed at the induction of effective T-cell responses against established tumors have not been successful in clinic and require the use of new adjuvants. One of those is a new adjuvant in which gangliosides are incorporated into the outer membrane protein complex of Neisseria meningitidis to form very small size proteoliposomes (VSSP). In a preclinical model of human papillomavirus HPV16-induced cervical cancer we show that vaccination with HPV 16 E7 derived minimal CTL peptide and VSSP protects mice against tumor challenge, induces regression of established tumors and produces E7-specific CD8+ T-cell responses.