The phase I study included patients with progressive prostate disease after primary surgery or radiotherapy. The dose-escalation study sought to determine the optimal and safe dose range of the adjuvant GPI-0100 when used with a bivalent conjugate vaccine (glycosylated MUC-2-KLH and Globo H-KLH).
In the prostate cancer patients treated, all of the vaccines containing GPI-0100 were found to be safe. Patients receiving the two GPI-0100 batches showed comparable grade I local reaction but slightly less grade II local reactivity using the more purified GPI-0100.
Overall, patients receiving GPI-0100 had significantly less pain or inflammation at the injection sites and fewer systemic symptoms compared to patients receiving rival saponin adjuvant QS-21 who had similar antibody titers.
The present study shows that GPI-0100 appears to be safe and to stimulate a strong immune response in human, warranting its use in further vaccine studies. The impact of immunotherapies on biomarkers such as PSA and their effects on disease progression has yet to be conclusively validated.
Vaccine adjuvants are integral for use in vaccine development as they help determine the nature of the body’s immune response and aid in directing the body to stimulate either the production of antibodies or cell-mediated immunity.
GPI-0100 is a semi-synthetic compound derived from saponins (naturally occurring glycosides) which acts by up-regulating the body’s immune system and stimulating both humoral and an effective T-cell immunity with CTL production.
GPI-0100 is currently being evaluated in phase I studies in breast and kidney cancer. Further clinical trials are being planned for melanoma, neuroblastoma, breast cancer, ovarian cancer and chronic myeloid leukemia patients.