Cell Genesys immunotherapy is patient specific

The patient-specific response observed in the Phase II trials is unusual for drugs developed for a wide range of patients. This ability to generate a broad and relevant immune response indicates the potential advantage of cell-based multi-antigen products. CellGenesys' GVAX immunotherapy has been developed as a potential 'off the shelf' pharmaceutical for use after hormonal therapy for advanced-stage prostate cancer. The biological therapy comprises two genetically-modified prostate cancer cell lines designed to stimulate the patient's immune system to respond and destroy cancer cells to which the body has become tolerant. The cells secrete the immune stimulatory hormone, GM-CSF (granulocyte-macrophage colony stimulating factor) to encourage immune cells to attack cancer cells. "The immune response data reported today provide added support for the concept that a whole-cell immunotherapy, such as GVAX immunotherapy for prostate cancer, is an ideal multi-antigen source that is capable of eliciting an immune response to a broad array of tumour-associated antigens,"​ said Dr Peter Working, senior vice president of Research and Development at Cell Genesys. "That the majority of antibody responses are unique to individual patients is further evidence that the non patient-specific format of GVAX immunotherapies is capable of inducing unique, patient-specific immune responses." ​ Results of a serological analysis of gene expression identified more than 148 proteins to which antibody response was induced with many of these previously unidentified as prostate cancer-associated antigens. ​"The fact that many of these antigens have not before been associated with prostate cancer, further suggests that a multivalent antigen immunotherapy like GVAX immunotherapy may provide the best potential for inducing an effective anti-tumor immune response, especially for heterogeneous cancers such as prostate cancer,"​ said Working.​ Similar patient specific immune responses were observed in trials of patients suffering from various other cancers. The Phase II GVAX trials showed that overall median survival rate for patients suffering from metastatic hormone-refractory prostate cancer patients was 26.2 months. This compares favourably to the 18.9 month survival rate for patients treated with Sanofi Aventis' taxotere (docetaxel) chemotherapy and prednisone.