Wyeth and Progenics may have hit a stumbling block in their efforts to gain approval of Relistor for post-operative ileus, reporting negative Phase III study results for the peripherally acting mu-opioid receptor antagonist May 22.

The Phase III study of an intravenous formulation of methylnaltrexone in post-operative ileus failed to meet either its primary or secondary endpoints, which were, respectively, reduction in time to recovery of gastrointestinal function and improved time to discharge eligibility. The firms announced another Phase III POI trial with a similar design had failed in early March.

"Progenics and Wyeth will now study the results of both Phase III intravenous POI studies and determine whether and how to continue development of this formulation of Relistor and this indication," the companies said.

The outcome places Relistor even further behind competitor Entereg (alvimopan) in the race to gain approval for POI. The GlaxoSmithKline/Adolor drug, taken in a 12 mg oral capsule, was cleared by FDA May 20 following a long regulatory haul (¹ Also see "Adolor/GSK’s Entereg Approved By FDA" - Pink Sheet, 20 May, 2008.).

Despite the bad news on the IV front, Wyeth/Progenics did report positive results from a Phase II oral study of opioid-induced constipation.

In the four-week study of 122 patients with chronic, nonmalignant pain receiving opioids, once-daily oral Relistor demonstrated statistically significant activity, measured by the occurrence of spontaneous bowel movements.

The companies are awaiting results of a second Phase II trial before determining whether to proceed with the oral formulation for OIC.

Relistor was approved in subcutaneous form in April for OIC in patients with advanced illness receiving palliative care (² Also see "Wyeth/Progenics’ Relistor: FDA Says Yes, EU Likes It, Too" - Pink Sheet, 24 April, 2008.).

-Brooke McManus (b.mcmanus@elsevier.com)

Wyeth/Progenics’ Relistor Fails Second Phase III POI Study

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