Phase 3 Trial
A Phase 3 trial run by Pharnext examining the safety and the efficacy of an investigative therapy called PXT3003 began in December of 2015. It enrolled 323 Charcot-Marie-Tooth disease type 1A (CMT1A) patients who were between the ages of 16 and 65. The primary endpoint was the level of physical disability.
This randomized and placebo controlled trial lasted 15 months. Some patients were given placebo twice each day, some were given a low dose of PXT3003 twice each day, and some were given a high dose of PXT3003 twice each day.
PXT3003 is an oral therapy that combines three drugs which have already been approved. This formulation has already received Orphan Drug Designation and Fast Track Designation from the FDA. The primary endpoint of this trial was successfully met which meant that it was time for an open-label extension study.
Open-Label Extension
This extension study allowed those who were in the Phase 3 trial to continue taking PXT3003. 187 enrolled out of the 323 original patients. The participants received the same dose of the therapy that they’d been given before except those who were previously given placebo were placed in either the high or low dose group at random.
Unfortunately, in 2017 there was a problem with the high dose formulation and there was a temporary pause. Moving forward, the high dose group received twice the amount of the formulation used in the low dose group.
The trial continued and at nine months the responses were positive for all of the treatment groups. Those who were given placebo in the first iteration of the trial who then switched to the therapy in the open-label extension showed significant improvements.
Even with the interruption, the therapy has shown it was able to maintain improvements for patients for approximately two years.
Looking Forward
So what happens next? First and foremost, the patients in the extension study will continue receiving PXT3003 until it becomes available commercially. A final report from this study will be published soon.
Additionally, the company has been talking with the FDA about starting another Phase 3 trial with the treatment. This will help to clear the air about any concerns from the complications that arose in the extension study. They hope to complete the protocol for this new trial soon.
It is this trial which will support their marketing authorization application for the therapy in Europe.
You can read more about these updates here.
