Prilenia shares top-line data from the PROOF-HD study of pridopidine in people with HD

CHDI Therapeutics Conference: Prilenia shares data from the PROOF-HD trial 

The CHDI Therapeutics conference is ongoing this week in Dubrovnik, Croatia. It’s one of the most important global meetings of academic and industry researchers working towards therapies for HD. The HDBuzz team, including HDSA’s Dr. Leora Fox, is live-tweeting the conference, and today’s talks are focused on clinical trials. You can also read the summaries of Day 1 and Day 2 (with Day 3 coming tomorrow!). We focus today on a major piece of clinical trial news.  

At the American Academy of Neurology meeting this Tuesday, April 25th, and at the CHDI Therapeutics meeting today, Prilenia shared top-line data from the PROOF-HD study of pridopidine in people with HD. Their community letter and press release are now publicly available. HDBuzz also covered the news in their most recent article. HDSA and the Huntington Society of Canada will host a research webinar on Friday, May 5th at 1:00 PM Eastern to talk directly with the community about the results. Prilenia CEO, Dr. Michael Hayden, MBChB, and Lead Principal Investigators will be there to present the data and answer community questions. Click here to register today.  

The goal of the trial was to understand if pridopidine could slow down the loss of abilities in HD, like the ability to work, manage a household or checkbook, and other tasks of day-to-day function. We were disappointed to learn that the trial did not meet its primary or secondary endpoints. This means that while pridopidine was safe, it did not have any effect on the major symptoms that the trial was measuring in people with HD, like the day-to-day abilities listed above, and aspects of movement, behavior, and thinking measured with common clinical tests. 

Importantly, Prilenia did a planned analysis where they separated participants into two groups, people who were taking neuroleptic medications for their HD symptoms, and people who were not taking neuroleptics. Neuroleptics are also known as antipsychotics, and they can be extremely helpful for some people with HD who experience major changes in their behavior and thinking patterns, like psychosis. They are also sometimes useful for controlling HD movements (chorea) – there are many reasons that an HD physician might prescribe a neuroleptic medication.  

What Prilenia found is that people who were not taking neuroleptics had an initial period during the trial (about a year) when pridopidine was helpful to them. For this reason, there may be some promise for pridopidine if given to people who are not taking neuroleptic drugs, though some researchers remain skeptical of this conclusion.  

It is important to understand that this news is not a reason to make abrupt changes to the medications a person is taking. It is always advisable to speak with a doctor before making this type of medical decision. We are not yet sure what is next for pridopidine, but many people who participated in the trial have chosen to continue taking the drug in an ongoing study known as an open-label extension.