FDA Places Prilenia’s Oral Pridopidine on Fast Track

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by Marta Figueiredo PhD |

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The U.S. Food and Drug Administration (FDA) has given fast track designation to Prilenia Therapeutics’ pridopidine as a potential oral treatment for Huntington’s disease.

This designation is given to therapies that show considerable potential in addressing serious conditions for which available treatments fall short. It is meant to speed their clinical development and regulatory review — enabling a rolling review and qualification for accelerated approval and priority review.

Rolling review means the company can submit sections of the regulatory application for review as they come ready, rather than waiting for every section to be completed before the application can be reviewed by the agency.

“Receipt of Fast Track designation from the FDA underscores the urgency to address a significant unmet need for patients with Huntington’s Disease,” Michael R. Hayden, PhD, Prilenia’s CEO and founder, said in a press release.

Huntington’s “is one of the most devastating neurodegenerative disorders, impacting not only patients but their families,” Hayden said, adding that “at the present time, there is no approved treatment to delay onset or slow disease progression.”

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“We look forward to working closely with the FDA in making pridopidine a potential option for these patients,” said Hayden, also a professor at the University of British Columbia, in Canada.

Henk Schuring, chief regulatory and commercialization officer at Prilenia, added: “The FDA Fast Track designation is an important milestone, as it provides opportunities to work collaboratively with the FDA to accelerate pridopidine’s development for the treatment of Huntington’s Disease.”

The therapy previously received orphan drug designation in both the U.S. and Europe for the same indication. This designation also is meant to expedite pridopidine’s development by providing regulatory support and financial benefits, as well as a marketing exclusivity period (of seven years in the U.S. and 10 in Europe) upon regulatory approval.

Pridopidine, previously owned by Teva Pharmaceuticals, is an orally available small molecule that selectively activates the sigma-1 receptor, a receptor protein present at high levels in the brain and spinal cord that boosts several key pathways for the maintenance of neuronal health and function.

One such pathway involves a neuroprotective protein called brain-derived neurotrophic factor, whose levels are reduced in people with Huntington’s.

In a previous Phase 2 clinical trial, called PRIDE-HD (NCT02006472), one year of treatment with 45 mg of pridopidine, given twice a day, was shown to significantly prevent functional decline in people with early stage Huntington’s, relative to a placebo.

Results from a Phase 2 long-term extension study, called OPEN-HART (NCT01306929), also supported these benefits, with patients treated for five years with that same pridopidine dose showing a significantly slower decline in functional capacity, compared with a group of patients given a placebo in a separate trial called 2CARE (NCT00608881).

These positive findings prompted the launch of the global Phase 3 PROOF-HD trial (NCT04556656) that earlier this month completed patient enrollment — surpassing the initial target, and ahead of schedule.

The placebo-controlled trial, conducted in collaboration with the Huntington Study Group, is evaluating pridopidine’s safety and effectiveness in 499 adults, 25 and older, with early stage Huntington’s.

Participants, recruited at sites in the U.S., Canada, and nine countries in Europe, will be assigned randomly to receive an oral capsule of either 45 mg of pridopidine or a placebo, twice a day for up to 78 weeks (roughly one-and-a-half years).

Patients are intended to take one capsule in the morning and one in the afternoon, with a seven- to 10-hour interval and irrespective of meals.

PROOF-HD’s main goal is to assess changes in the Unified Huntington’s Disease Rating Scale–Total Functional Capacity (UHDRS-TFC) — a tool used to assess Huntington’s stage and the level of a patient’s functionality — after 65 weeks (about 16 months).

Secondary goals include the proportion of patients responding to treatment (no worsening in UHDRS-TFC), and changes in Huntington’s motor and behavioral symptoms and in quality of life.

Top-line results are expected in the early 2023.

After completing the trial, participants will have the option of enrolling in an open-label extension study, in which all will be given pridopidine.

Prilenia also is evaluating pridopidine as a potential therapy for people with other neurodegenerative diseases, such as amyotrophic lateral sclerosis.