Wyeth and Progenics Announce Preliminary Clinical Trial Results for RELISTOR Oral and Intravenous Formulations

Collegeville, Pa., and Tarrytown, N.Y. — Wyeth Pharmaceuticals, a division of Wyeth (NYSE: WYE), and Progenics Pharmaceuticals, Inc. (Nasdaq: PGNX), today announced preliminary results from two clinical trials conducted with investigational oral and intravenous formulations of RELISTOR™ (methylnaltrexone bromide).

The first of these studies, a phase 2 trial, evaluated the effects of an oral formulation of RELISTOR for the treatment of opioid-induced constipation (OIC), in patients with chronic, non-malignant pain. This study showed positive activity.

The second study, a phase 3 trial, examined the use of an intravenous formulation of RELISTOR for post-operative ileus (POI). In this study, the drug did not meet its primary or secondary end points.

RELISTOR Oral Formulation

The study of the RELISTOR oral formulation was a double-blind, randomized, placebo-controlled phase 2 trial. In this four-week trial of 122 patients with chronic, non-malignant pain (such as back pain, neuropathic pain or osteoarthritis) who were receiving opioids for pain management, the once daily oral formulation of RELISTOR showed statistically significant activity as assessed by the occurrence of spontaneous bowel movements and other efficacy measures. This oral formulation was also shown to be generally well tolerated.

“We are pleased by the preliminary findings of this oral formulation” says Paul J. Maddon, M.D., Ph.D., Founder, Chief Executive Officer and Chief Science Officer of Progenics Pharmaceuticals, Inc. “We await results within the coming months from a second, ongoing phase 2 study involving the oral formulation of RELISTOR that was announced last July to have positive activity in a phase 1 trial.”

RELISTOR Intravenous Formulation

The Progenics-conducted phase 3 study of an intravenous formulation of RELISTOR for patients with post-operative ileus (POI) did not meet the primary or secondary end points, confirming the earlier findings of the Wyeth phase 3 intravenous POI study announced on March 12, 2008. Progenics and Wyeth will now study the results of both phase 3 intravenous POI studies to determine whether and how to continue development of this formulation of RELISTOR and this indication.

RELISTOR Franchise

“We are committed to continuing to develop the RELISTOR franchise to help address the unmet medical needs of patients suffering from the gastrointestinal side effects of opioids. Following the results from a second phase 2 clinical trial of another oral formulation, Wyeth and Progenics will further define the continued development plan for oral RELISTOR,” says Gary L. Stiles, M.D., Executive Vice President, Chief Medical Officer, Wyeth Pharmaceuticals.

About RELISTOR and Opioids

RELISTOR is a peripherally acting mu-opioid receptor antagonist that counteracts the constipating effects of opioid pain medications in the gastrointestinal tract without affecting their ability to relieve pain.

Opioids provide pain relief by specifically interacting with mu-opioid receptors within the central nervous system (CNS) – the brain and spinal cord. However, opioids also interact with mu-opioid receptors found outside the CNS, such as those within the gastrointestinal tract, resulting in constipation that can be debilitating. RELISTOR selectively displaces opioids from the mu-opioid receptors outside the CNS, including those located in the gastrointestinal tract, thereby decreasing their constipating effects. Because of its chemical structure, RELISTOR does not affect the opioid-mediated analgesic effects on the CNS.

About Subcutaneous RELISTOR

On April 24, 2008, the United States Food and Drug Administration approved RELISTOR subcutaneous injection for the treatment of OIC in patients with advanced illness who are receiving palliative care, when response to laxative therapy has not been sufficient. The use of RELISTOR beyond four months has not been studied. Wyeth expects to make subcutaneous RELISTOR available in the United States in early June. Subcutaneous RELISTOR has also been approved in Canada and is awaiting Australian approval and European approval, having received a positive opinion from the Committee for Medicinal Products for Human Use (CHMP), the EMEA scientific committee, in April.

Important Safety Information for Subcutaneous RELISTOR

• RELISTOR is contraindicated in patients with known or suspected mechanical gastrointestinal obstruction.
• If severe or persistent diarrhea occurs during treatment, advise patients to discontinue therapy with RELISTOR and consult their physician.
• Use of RELISTOR has not been studied in patients with peritoneal catheters.
• The most common adverse reactions with RELISTOR in clinical trials were abdominal pain, flatulence, and nausea.