Pain Therapeutics says Oxytrex phase 3 trial for chronic pain failed due to high drop-out rate

By E. Janene Geiss

Philadelphia, Nov. 22 - Pain Therapeutics, Inc. said Tuesday that results of a 775-patient phase 3 trial with investigational drug Oxytrex failed to reach its primary endpoint of statistical significance due to a high drop-out rate in all study arms.

The predefined endpoint was reduction in physical dependency as measured by SOWS. The company said it expected Oxytrex to reduce physical dependency by 25% or more.

In the trial, the drug did reduce dependency by 28% compared to an equivalent dose of oxycodone, but this result did not reach statistical significance because of the drop-out rate, officials said in a company news release.

The company said it anticipated that up to 40% of patients would drop-out before completing the study's three-month treatment period. Actual drop-out rates were 48% to 60% in the drug arms and 37% in the placebo arm, officials said.

The number of patients completing the study was lower than expected and, given the statistical rigor of the study design, statistical significance was not reached in the primary endpoint.

"We believe the weight of all evidence, including prior clinical and non-clinical data, continues to favor Oxytrex over oxycodone," Pain Therapeutics president and chief executive officer Remi Barbier said in the release. "We remain steadfast to the Oxytrex program and its ability to reduce physical dependency."

The company said it plans in early 2006 to discuss with the U.S. Food and Drug Administration ways to design the clinical trials so to overcome statistical limitations imposed by very high drop-out rates.

The study met its predefined secondary endpoint. During the three-month treatment period, Oxytrex was non-inferior to oxycodone, officials said. Oxytrex patients reported slightly better pain relief than oxycodone patients and significantly better analgesia than placebo patients. In contrast, oxycodone did not separate from placebo, given the high drop-out rate and placebo response, officials said.

Pain Therapeutics is a South San Francisco, Calif., biopharmaceutical company with drug candidates that target different types of chronic pain.

© 2015 Prospect News.
All content on this website is protected by copyright law in the U.S. and elsewhere. For the use of the person downloading only.
Redistribution and copying are prohibited by law without written permission in advance from Prospect News.
Redistribution or copying includes e-mailing, printing multiple copies or any other form of reproduction.