Pfizer Inc's investigational new drug SUTENT/SU11248 (sunitinib malate) more than doubled survival and significantly reduced tumor growth and spread in a Phase III study in patients with Gleevec-resistant gastrointestinal stromal tumors (GIST). Encouraging Phase II results also were observed in other tumor types, including metastatic renal cell carcinoma (mRCC), metastatic breast cancer and neuroendocrine tumors, according to new data presented this week at the annual meeting of the American Society of Clinical Oncology (ASCO).

"These data support SUTENT's activity against hard-to-treat tumors, particularly GIST and mRCC, both potentially life-threatening and with few, if any, other options," said Dr. John LaMattina, Pfizer president of worldwide research and development.

SUTENT is a highly selective, multi-targeted tyrosine kinase inhibitor that starves tumors of blood and nutrients needed for growth and simultaneously kills cancer cells that make up tumors.

GIST Studies

* Results from a double-blind Phase III study of more than 300 GIST patients resistant to or intolerant of the standard treatment Gleevec(R) (imatinib mesylate) showed SUTENT significantly prolonged the time to tumor progression (6.3 months on SUTENT vs. 1.5 months for controls) and reduced the risk of death by approximately 50 percent compared to placebo.

* In addition, long-term follow-up data from the Phase I/II GIST study that served as the basis for the larger Phase III trial demonstrated that SUTENT extended overall survival to nearly 20 months in patients whose cancer had progressed despite treatment with other standard therapies. In addition, the median time to tumor progression in this study was 7.8 months for all patients, with some specific subtypes of patients benefiting even more dramatically than would be expected with Gleevec.

"These results substantiate the concept that multi-targeted molecular therapy can overcome resistance to other targeted drugs in cancer," said Dr. George Demetri of Harvard University's Dana-Farber Cancer Institute in Boston, the lead investigator on the SUTENT trial for GIST. "We think that SUTENT may have a broad spectrum of activity for many different forms of cancer beyond what we have seen in patients with GIST. We believe that SUTENT is an important step forward in cancer therapy."

Metastatic Renal Cell Carcinoma

Data from two Phase II studies showed patients with resistant renal cell, or kidney, tumors who received SUTENT experienced high response rates and delayed tumor progression.

* Results from a 63-patient trial showed 40 percent of patients responded to treatment with SUTENT as measured by standard response criteria. Tumors did not progress for more than three months in an additional 28 percent of patients, indicating that 68 percent of patients benefited from SUTENT treatment. In addition, the average time to tumor progression for patients in this study was 8.7 months, and the median overall survival was 16.4 months.

* A second Phase II study of 106 patients demonstrated an objective response rate of 39 percent in patients treated with SUTENT. In addition, 23 percent of patients experienced tumor stabilization. Taken together, a total of 62 percent of patients benefited from treatment with SUTENT.

"Results from these two studies suggest that SUTENT has substantial anti-tumor activity in metastatic renal cell carcinoma as second-line therapy and form the basis for the launch of a large-scale phase III program to determine the potential benefits of SUTENT in earlier stage disease," said lead study investigator Dr. Robert Motzer, attending physician at Memorial Sloan-Kettering Cancer Center. "These studies also contribute to an emerging body of data indicating that agents simultaneously targeting multiple receptors will provide new options for renal cell patients."

Preliminary Data on Breast and Neuroendocrine Cancers

* Preliminary results from a Phase II study of SUTENT in patients with inoperable neuroendocrine tumors will be presented on Sunday, May 15.

* Preliminary results from a Phase II study evaluating SUTENT in the treatment of patients who had received other standard therapies for breast cancer will be presented on Monday, May 16.

The most commonly reported adverse events in SUTENT clinical trials were generally mild to moderate in severity and reversible upon discontinuation of treatment. The most common severe adverse events included fatigue, myelosuppresion (low white blood cell counts) and gastrointestinal upset (diarrhea, nausea and vomiting). The complete adverse event profile of SUTENT is not yet known.

SUTENT has not yet been approved by the U.S. Food and Drug Administration or other global regulatory agencies.

About Pfizer Oncology

Pfizer Oncology is committed to advancing the scientific understanding of cancer and to bringing new medicines to address unmet medical needs in cancer patients. Oncology is a research priority for Pfizer, with over 12 percent of the company's research and development investment devoted to discovering and developing innovative therapies for treating breast, colorectal and other cancers.

DISCLOSURE NOTICE: The information contained in this document is as of May 14, 2005. Pfizer assumes no obligation to update any forward-looking statements contained in this document as a result of new information or future events or developments.

This release contains forward-looking information about a product in development and the potential efficacy of such product that involves substantial risks and uncertainties. Such risks and uncertainties include, among other things, the uncertainty of the success of the research and development activities; decisions by regulatory authorities regarding whether and when to approve any new drug application for a product candidate that may result from the research, as well as their decisions regarding labeling and other matters that could affect the commercial potential of such product candidate; and competitive developments.

A further list and description of risks and uncertainties can be found in the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2004, and in its reports on Form 10-Q and Form 8-K.

Pfizer Inc