Active immunotherapy of human solid tumor with autologous cells treated with cholesteryl hemisuccinate. A Phase I study.

A marked increase in specific immunogenicity of tumor cells is induced upon incorporation of cholesteryl hemisuccinate (CHS) into the cell membrane, which presumably promotes the expression of latent tumor-associated antigens. Immunotherapy with CHS-treated and irradiated tumor cells as vaccine was found to be very effective in various murine experimental tumors and in eliciting delayed-type hypersensitivity in cancer patients. Based on these findings, we have carried out a Phase I study on 21 patients with solid tumor who had exhausted standard therapeutic options. All participating patients were examined by conventional physical and clinical tests prior and during the study. The immunotherapy regimen for most patients consisted of an intramuscular injection of 2 X 10(7) CHS treated and irradiated autologous tumor cells given at 2-week intervals. Variations on this regimen were mostly due to the lack of sufficient number of cells. None of the patients displayed evidence of toxicity or any other local or systemic adverse effects. In seven patients, regression of tumor mass was observed. In six of nine patients who were tested for delayed-type hypersensitivity against their CHS treated tumor cells, a significant increase in skin reaction was observed after immunotherapy. The lack of any adverse reaction in this treatment, in addition to the observed positive clinical and immunologic response in advanced cancer patients, indicate a safe therapeutic potency which is planned to be investigated in the subsequent clinical studies.