Trial of Bi-shRNA-furin and GMCSF Augmented Autologous Tumor Cell Vaccine for Advanced Cancer

Preliminary studies with a variety of vaccines suggest target accessibility (potential immunogenicity) in a variety of solid tumors to immune directed approaches. In an effort to overcome limitations of immunostimulatory cancer vaccines, we have designed a novel autologous vaccine to address inability to fully identify cancer associated antigens, antigen recognition by the immune system (i.e. antigen to immunogen), effector potency, and cancer-induced resistance. We have completed clinical investigations using two different gene vaccine approaches to induce enhancement of tumor antigen recognition which have demonstrated therapeutic efficacy. Specifically, both the use of a GMCSF gene transduced vaccine (GVAX®) and a TGFβ2 antisense gene vaccine (Lucanix®), in separate trials, have demonstrated similar beneficial effects without any evidence of significant toxicity in advanced cancer patients. The GMCSF transgene directly stimulates increased expression of tumor antigen(s) and enhances dendritic cell migration to the vaccination site. TGFβ2 blockade following intracellular TGFβ2 antisense gene expression reduces production of immune inhibiting activity at the vaccine site. This appears to be one of the primary mechanisms of inhibition of immune responsiveness in glioblastoma and lung cancer. In a subsequent Phase I trial we combined both active principles in one autologous vaccine, TAG. TAG vaccine has an excellent safety profile in the first nineteen patients treated (enrollment open to any solid tumor) with one documented CR (melanoma). However, TGFβ1 is the dominant TGFβ family inhibitory effector in the majority of other solid tumors. We describe a unique method of inhibiting both TGFβ1 and TGFβ2 through RNA interference with Furin. We will harvest autologous cancer cells from patients with advanced refractory cancer. We have constructed a bi-shRNAfurin / GMCSF (Vigil™) expression vector plasmid and have successfully demonstrated preclinical activity of the vector function following transfection by electroporation and irradiation of ex vivo autologous tumor cells.