UPDATE 2-Endo says analysis suggests pain drug effective

(Adds details, analyst comment, share price, byline)

By Ransdell Pierson

NEW YORK, Dec 17 (Reuters) - Endo Pharmaceuticals Holdings Inc (ENDP.O) said on Monday that an interim analysis suggests that its Rapinyl experimental cancer pain drug was highly effective and met all secondary goals of a late-stage clinical trial.

The data indicate Rapinyl achieved its primary goal of relieving breakthrough cancer pain within 30 minutes, and did so by a highly statistically significant margin, the company said.

Breakthrough cancer pain is a brief flare-up of severe pain that occurs even while the patient is regularly taking medication for cancer pain.

Endo, whose shares rose almost 2 percent, previously had announced it was having difficulty recruiting cancer patients in the trial and would therefore take an "interim" look at data among patients who had already been tested in the study.

Given the favorable interim analysis of 61 patients in the Phase 3 trial, Endo said it was terminating the efficacy portion of that study, while continuing with a safety portion.

The company said it would continue to enroll patients in a second late-stage safety study, with results meant to confirm those of the companion Phase 3 study.

Even as patient enrollment proceeds in the second Phase 3 trial, the Chadds Ford, Pennsylvania-based company said it is considering whether to seek approval of its product based upon available data from the first Phase 3 study. Endo said it would provide investors an update early next year about development plans for the medicine.

Although analysis of the data was meant only to determine effectiveness of the drug, Endo said side effects among patients taking it were consistent with those usually observed with other opioids.

Rapinyl is an oral fast-dissolving form of the widely used opioid drug fentanyl. Endo licensed North American marketing rights to the medicine from Orexo AB (ORX.ST), a Swedish company that specializes in drug-delivery technology.

Fentanyl is the active ingredient of Johnson & Johnson's (JNJ.N) Duragesic pain patch and generic forms of the product. The compound is about 80 times more potent than morphine, and, like morphine, can be highly addictive.

Corey Davis, an analyst with Natixis Bleichroeder, called the data a "positive step" for Rapinyl and said they suggest the product has similar effectiveness and speed of action as Cephalon Inc's (CEPH.O) Fentora product, which is approved to treat breakthrough cancer pain.

But Davis cautioned it remains unclear whether the new interim data on Rapinyl will be adequate to support a marketing application. He also noted that a rival fentanyl product developed by BioDelivery Sciences International Inc (BDSI.O) is already awaiting marketing approval.

Davis, who has a "hold" rating on Endo, said the favorable data on Rapinyl are overshadowed by possible generic competition for two Endo products. The are Opana, Endo's morphine-like opioid for long-term control of moderate to severe pain, and the company's Lidoderm patch to control pain after shingles.

"We remain on the sidelines on the name as we think Endo will have substantial overhang despite its decent earning prospect," Davis said in a research note.

Shares of Endo were up 47 cents to $27.59 in midday trading on the Nasdaq. It has traded during the past year in a range between $26.04 and $35.85. (Reporting by Ransdell Pierson; editing by Lisa Von Ahn and Gerald E. McCormick)