Cell Genesys and Medarex Report Follow-Up Data From a Phase 1 Combination Therapy Trial With GVAX Immunotherapy for Prostate Cancer and Ipilimumab (MDX-010) Antibody
Monday June 4, 7:00 am ET
[A somewhat luke-warm comment from Nichol]
SOUTH SAN FRANCISCO, Calif. and PRINCETON, N.J., June 4 /PRNewswire-FirstCall/ -- Cell Genesys, Inc. (Nasdaq: CEGE - News) and Medarex, Inc. (Nasdaq: MEDX - News) today announced follow-up data from the ongoing Phase 1 clinical trial in patients with advanced prostate cancer receiving Cell Genesys' GVAX immunotherapy for prostate cancer administered in combination with ipilimumab (MDX-010), a fully human anti-CTLA-4 antibody that is being jointly developed by Medarex and Bristol-Myers Squibb Company. The new data reported today includes median follow-up of 18 months on the first twelve patients enrolled in the trial, as well as immunologic and biochemical analyses of the effects of the combination treatment. These data were presented over the weekend by Winald Gerritsen, M.D., Ph.D., director of the University Hospital Vrije Universiteit Cancer Center in Amsterdam, at the annual meeting of the American Society of Clinical Oncology (ASCO) being held in Chicago, IL.
In the ongoing Phase 1 combination therapy trial of GVAX immunotherapy for prostate cancer and ipilimumab, twelve patients with advanced prostate cancer have completed the combination regimen to date. Of the six patients who have received the two highest doses, antitumor activity has been observed in five patients, including prostate-specific antigen (PSA) declines of greater than 50% that were maintained in four of these patients for at least six months, with the longest response to date at approximately 16 months. Clinical evidence of antitumor activity has been observed in four of these five PSA responders, including complete resolution of multiple lesions on bone scan in two patients, and resolution of abdominal lymph node disease by CT scan and improvement in bone pain in one patient each. The five patients with PSA declines experienced either Grade 2 or 3 immune-mediated endocrine deficiencies similar in type to those previously reported with ipilimumab therapy, and were successfully treated with standard hormone replacement therapy. Importantly, the PSA declines could not be consistently correlated with declines in adrenal androgens and there was no induction of the alpha-21-hydroxylase auto-antibody that is seen in 90% of cases of auto-immune adrenal insufficiency. Two patients requiring thyroid replacement therapy were successfully tapered off after recovery of thyroid function, with one patient subsequently maintaining a PSA response. One patient who received the highest dose of ipilimumab tested in the trial developed a Grade 3 dose-limiting pulmonary alveolitis that responded to steroid treatment. Immunomonitoring studies showed that the combination therapy enhanced T cell and dendritic cell activity, which was more pronounced at the higher dose levels. Evaluation of antibody responses shows that the combination therapy can induce antibody responses to a broad array of previously identified cancer-associated antigens including PSMA, NY-ESO-1 and filamin-B, and that these responses were patient-specific with respect to the pattern of antibodies detected in different patients.
"We continue to be encouraged by the frequency and durability of both PSA and bone scan responses observed in the first twelve patients on this trial, and look forward to the evaluation of the additional patients currently being enrolled on this trial," stated Rob Dow, M.D., chief medical officer of Cell Genesys. "We continue to believe that the clinical evidence of antitumor activity seen in this combination immunotherapy trial provides further support for our ongoing Phase 3 trials of GVAX immunotherapy for prostate cancer."
"We are pleased with the data so far and look forward to analyzing further data as additional patients enroll in the study," said Geoffrey M. Nichol, M.B.Ch.B., senior vice president, Product Development at Medarex.
The ongoing Phase 1 combination therapy trial of GVAX immunotherapy for prostate cancer and ipilimumab is expected to enroll a total of approximately 25 to 30 patients with metastatic, hormone-refractory prostate cancer (HRPC). The dose for GVAX immunotherapy for prostate cancer is the same dose currently being tested in Cell Genesys' VITAL-1 Phase 3 trial. The dose for ipilimumab was escalated in sequential groups of three patients and has now reached dose levels associated with therapeutic activity. Additional patients are currently enrolling at a dose level at which therapeutic effects have been seen.
About GVAX immunotherapy for prostate cancer
GVAX immunotherapy for prostate cancer is currently being studied as a single agent and in combination with docetaxel chemotherapy in two Phase 3 clinical trials expected to enroll approximately 1200 patients with metastatic HRPC. Cell Genesys received Special Protocol Assessments (SPA) from the Food and Drug Administration (FDA) for each of the Phase 3 studies and has also received Fast Track designation for the product. Cell Genesys' ongoing Phase 3 program is designed to demonstrate an improvement in survival for GVAX immunotherapy for prostate cancer and is supported by consistent median survival results from two, independent, multi-center Phase 2 clinical trials (median survival of 34.9 months and 35.0 months, respectively, for the patients who received doses comparable to the Phase 3 dose), results that compare favorably to the previously published median survival of 18.9 months for metastatic HRPC patients treated with Taxotere® (docetaxel) chemotherapy plus prednisone, the current standard of care. GVAX immunotherapy for prostate cancer is comprised of two prostate cancer cell lines that have been modified to secrete GM-CSF (granulocyte-macrophage colony stimulating factor), an immune stimulatory hormone, and irradiated for safety. GVAX cancer immunotherapy for prostate cancer is being developed as a non patient-specific, "off-the-shelf" pharmaceutical product. |
