Wyeth Pharmaceuticals, a division of Wyeth (NYSE: WYE), announced data from an open-label phase 2 clinical trial of neratinib (HKI-272) in women with advanced HER-2-positive breast cancer. These data suggest that neratinib has antitumor activity in patients with advanced breast cancer positive for the ErbB-2 receptor (also known as HER-2 or Neu). These data were presented today during an oral session at the CTRC-AACR San Antonio Breast Cancer Symposium.

Neratinib is an investigational orally-administered potent and irreversible dual inhibitor of the HER-2 and EGFR kinases. Wyeth expects to initiate the first study in a global phase 3 program for neratinib in advanced HER-2-positive breast cancer later this month.

"Neratinib demonstrated activity against trastuzumab-resistant and trastuzumab-naive HER-2-positive breast cancer," said Harold Burstein, M.D., Ph.D., a study lead investigator at Dana-Farber Cancer Institute in Boston. "These results warrant ongoing study to see whether neratinib will fit into our armamentarium of anti-HER2 drugs."

The phase 2 study evaluated the safety and efficacy of a daily 240 mg oral dose of neratinib in 136 women diagnosed with ErbB-2-positive locally advanced or metastatic breast cancer (stage IIIB, IIIC or IV). The primary end point of the open-label, two-arm study was the 16-week progression-free survival (PFS) rate. Secondary end points included safety, objective response rate (complete and partial responses) and clinical benefit rate (objective response plus stable disease).

Patients were assigned to one of two study arms based on prior treatment with trastuzumab (Herceptin(R), Genentech), the standard of care for the treatment of advanced ErbB-2-positive breast cancer. Women enrolled in arm A (n=66) had either previously received at least six weeks of standard trastuzumab treatment or had experienced disease progression during or following trastuzumab-containing adjuvant therapy. Women in arm B (n=70) received no prior treatment with any ErbB-2-targeted therapy, including trastuzumab.

The efficacy analysis included 127 evaluable patients, 61 in arm A and 66 in arm B. In patients who were previously treated with trastuzumab (arm A), the 16-week PFS rate was 60 percent, and the median PFS was 23 weeks, as evaluated by independent assessment. The objective response rate was 26 percent, and the clinical benefit rate was 36 percent. In patients who had not received trastuzumab treatment (arm B), the 16-week PFS rate was 77 percent, and the median PFS was 40 weeks by independent assessment. The objective response rate was 56 percent, and the clinical benefit rate was 68 percent.

Adverse events of any grade occurring in more than 15 percent of study patients included diarrhea, nausea, vomiting, fatigue, anorexia, abdominal pain, headache and rash. Diarrhea was the most common toxicity and was observed in 93 percent of patients. Diarrhea was also the most significant grade 3 or 4 adverse event, occurring in 21 percent of patients. Diarrhea was reversible and generally manageable by medication, treatment interruption or dose reduction. One patient discontinued treatment due to diarrhea.

"Wyeth's exploration of neratinib demonstrates our ongoing commitment to research of promising investigational therapies in areas of significant unmet medical need, including oncology and women's health," says Gary L. Stiles, M.D., Chief Medical Officer, Wyeth. "These phase 2 data provide important insight into the potential clinical utility of neratinib in HER2-positive breast cancer."

The American Cancer Society estimates more than 182,000 women in the United States will be diagnosed with breast cancer in 2008, and more than 40,000 will die from the disease. The HER-2 receptor is over expressed in 25 percent to 30 percent of breast cancer patients.

About WyethPharmaceuticals

Wyeth Pharmaceuticals, a division of Wyeth, has leading products in the areas of women's health care, infectious disease, gastrointestinal health, central nervous system, inflammation, transplantation, hemophilia, oncology, vaccines and nutritional products.

Wyeth is one of the world's largest research-driven pharmaceutical and health care products companies. It is a leader in the discovery, development, manufacturing and marketing of pharmaceuticals, vaccines, biotechnology products, nutritionals and non-prescription medicines that improve the quality of life for people worldwide. The Company's major divisions include Wyeth Pharmaceuticals, Wyeth Consumer Healthcare and Fort Dodge Animal Health.

The statements in this press release that are not historical facts are forward-looking statements that are subject to risks and uncertainties that could cause actual results to differ materially from those expressed or implied by such statements. In particular, clinical trial data are subject to differing interpretations, and the views of regulatory agencies, medical and scientific experts and others may differ from ours. There can be no assurance that neratinib will ever receive regulatory approval or be successfully developed and commercialized. Other risks and uncertainties that could cause actual results to differ materially from those expressed or implied by forward-looking statements include, without limitation, the inherent uncertainty of the timing and success of, and expense associated with, research, development, regulatory approval and commercialization of our products and pipeline products; government cost-containment initiatives; restrictions on third-party payments for our products; substantial competition in our industry, including from branded and generic products; emerging data on our products and pipeline products; the importance of strong performance from our principal products and our anticipated new product introductions; the highly regulated nature of our business; product liability, intellectual property and other litigation risks and environmental liabilities; uncertainty regarding our intellectual property rights and those of others; difficulties associated with, and regulatory compliance with respect to, manufacturing of our products; risks associated with our strategic relationships; economic conditions including interest and currency exchange rate fluctuations; changes in generally accepted accounting principles; trade buying patterns; the impact of legislation and regulatory compliance; risks and uncertainties associated with global operations and sales; and other risks and uncertainties, including those detailed from time to time in our periodic reports filed with the Securities and Exchange Commission, including our current reports on Form 8-K, quarterly reports on Form 10-Q and annual report on Form 10-K, particularly the discussion under the caption "Item 1A, Risk Factors" in our Annual Report on Form 10-K for the year ended December 31, 2007, which was filed with the Securities and Exchange Commission on February 29, 2008. The forward-looking statements in this press release are qualified by these risk factors. We assume no obligation to publicly update any forward-looking statements, whether as a result of new information, future developments or otherwise.

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