Patients Who Took Investigational Melanoma Compound CP-675,206 Showed Favorable Survival Outcomes, Pfizer Says

Data on Pfizer’s investigational compound CP-675,206, which works by a novel mechanism of action and represents a new generation of immunotherapy, were presented today at the 43rd American Society of Clinical Oncology (ASCO) Annual Meeting. In a phase II study of patients with advanced melanoma, median overall survival was 10.3 months (10 mg/kg monthly dose) and 11.2 months (15 mg/kg quarterly dose). In the open label, phase I portion of the study, an estimated 21.7 month median overall survival was observed across several dose groups of CP-675,206 (3, 6, and 10 mg/kg) in 28 melanoma patients. "The five year overall survival rate of patients with metastatic melanoma remains among the poorest of any cancer type,” said Charles Baum, MD PhD, head of oncology development at Pfizer. "Despite decades of research, no therapy has emerged that has conclusively offered these patients a meaningful improvement in overall survival. These studies show that CP-675,206 may be an efficacious compound as a single-agent treatment, which would potentially benefit melanoma patients who have few treatment options beyond surgery. These data further support the ongoing research with CP-675,206 as a single agent therapy for first line metastatic and refractory melanoma patients.” The number of objective responses, defined as partial or complete tumor shrinkage by radiological scan, was comparable in both the quarterly and monthly dosing regimens (three vs. four objective responses in each arm, respectively). There was, however, a trend towards a lower incidence of Grade III and IV adverse events in patients who received quarterly versus monthly doses of CP-675,206 (31 per cent vs. 41 per cent; P = 0.42). CP-675,206 Study Details The multi-dose phase I/II trial was conducted in patients with histologically confirmed stage IIIc (unresectable) or stage IV recurrent metastatic melanoma. The study consisted of a phase I, open-label, multidose study (3, 6, and 10 mg/kg) with a phase I/II expansion cohort. The primary endpoint was safety in phase I and immune monitoring in the expansion cohort. The phase I study was followed by a phase II open-label portion of the study of 10 mg/kg monthly and 15 mg/kg quarterly dosing regimens. The primary endpoint in this study was response rate, and survival was analyzed as a secondary endpoint. In the Phase II study, two patients at the monthly dose and five patients at the quarterly dose continued on the study beyond a year. To date, six patients at monthly dosing have been discontinued due to toxicity (three diarrhea/colitis [1 requiring colectomy], one Grave’s ophthalmopathy, one pancreatitis, one hypersensitivity reaction) and two patients at the quarterly dose (colitis and pancreatitis, diarrhea) (P = 0.14). There were no drug-related deaths in this study. Pfizer Oncology is investigating a new generation of immunotherapies that aim to overcome tumor induced immune suppression. These novel agents target specific regulatory checkpoints in the immune cascade. CP-675,206 is a fully-human anti-CTLA4 monoclonal antibody that blocks a negative signal that down-regulates immune cells (known as T-cells). This is believed to help the immune system to seek out and destroy tumors. For more information on Pfizer Oncology please visit www.pfizer.com. DISCLOSURE NOTICE: The information contained in this release is as of June 3, 2007. Pfizer assumes no obligation to update any forward-looking statements contained in this release as the result of new information or future events or developments. This release contains forward-looking information about various products in development, including their potential benefits, that involves substantial risks and uncertainties. Such risks and uncertainties include, among other things, the uncertainties inherent in research and development; decisions by regulatory authorities regarding whether and when to approve any drug applications that may be filed for any such products in development as well as their decisions regarding labeling and other matters that could affect their availability or commercial potential; and competitive developments. A further description of risks and uncertainties can be found in Pfizer’s Annual Report on Form 10-K for the fiscal year ended December 31, 2006 and in its reports on Form 10-Q and Form 8-K.