Clinical Data This poster presentation provided immune response and disease free survival data from the first treatment group. CD8+ and FoxP3 T cell expression were evaluated in tumor samples obtained before and after surgery. In addition, ELISpot analysis was performed to determine the number of T cells capable of secreting IFN-γ in response to HPV antigen stimulation. Four of five subjects had robust T cell response as measured by blood ELISpot assay and the same four subjects also showed an average increase of 60% of CD8+ to FoxP3 ratio measured by immunohistochemistry post vaccination, demonstrating increased infiltration of CD8+ T cells as well as reduction of regulatory T cells measured by FoxP3 expression in tumor tissue. These four subjects remained disease free with follow-up ranging from nine to 24 months to date. One subject with only a marginal increase in ELISpot response magnitude to HPV and no increase in CD8+/FoxP3 ratio in tumor tissue post INO-3112 developed progressive disease at 11 months post-treatment.
Overall the characteristics of these immune response data mirrored those previously observed in a phase IIb clinical study of VGX-3100 for HPV-associated cervical dysplasia. In that study, strong CD8+ T cell immune responses were positively correlated with achievement of primary and secondary efficacy endpoints. VGX-3100 is the first therapy to demonstrate that activated killer T cells induced in the body have the power to clear neoplastic lesions as well as the virus which caused the disease.