New gene therapy for OPMD shows lasting success in small US trial
4 patients have seen their swallowing ability improve after one-time treatment
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Four people with oculopharyngeal muscular dystrophy (OPMD), a disease type marked by swallowing difficulties, experienced long-lasting improvements in their ability to swallow after receiving the gene therapy candidate BB-301 in an ongoing clinical trial.
That’s according to an update from therapy developer Benitec Biopharma, which announced new data from the small trial (NCT06185673), which is testing the experimental gene therapy in an estimated 30 people with OPMD at a single U.S. site.
“We continue to be encouraged by the benign safety profile and the durability of efficacy demonstrated in our BB-301 clinical development program,” Jerel A. Banks, MD, PhD, Benitec’s executive chairman and CEO, said in a company press release.
A form of muscular dystrophy, OPMD is characterized by weakening in the muscles of the eyes and throat. Dysphagia, or difficulty swallowing, is a symptom that affects almost everyone with OPMD.
The disorder is caused by mutations in the PABPN1 gene. Benitec’s gene therapy BB-301 is designed to simultaneously turn off the mutated gene and deliver a healthy version of it — a so-called silence-and-replace strategy. The therapy is administered by injection directly into the throat muscles.
Benitec is running a Phase 1b/2a study to test different doses of BB-301 in OPMD patients ages 65 and younger. Participants first complete six months in a natural history study — that is, a study to track disease activity without treatment — and then receive BB-301. All participants are then monitored with the goal of assessing long-term safety outcomes and the therapy’s effect on swallowing measurements.
All 4 patients self-reported swallowing gains
The new analysis covers outcomes from four patients who have been followed for at least one year after treatment with a low dose of BB-301.
The researchers looked at five different measures of swallowing abilities: one patient-reported questionnaire, one test that measures how long it takes to drink a cold glass of water, and three imaging-based evaluations that measure the activity of throat muscles and the efficiency of swallows.
Across the five measures, statistical tests were used to determine whether or not each patient had experienced meaningful improvement. Patients were considered responders if they showed improvement in at least two of the five measures after one year.
All four evaluated patients were responders, according to the testing results. One individual showed meaningful improvements across three of the swallowing assessments, while the other three improved across four of five domains.
Each of the four reported significant improvements in the self-reported assessment of swallowing ability, known as the Sydney Swallow Questionnaire or SSQ.
One of these patients has now been followed for two years after BB-301 treatment. For this individual, SSQ scores continued to improve over the second year of follow-up, according to Benitec. The developer said this individual also showed continual improvements in one of the imaging-based assessments of swallowing.
Trial now testing OPMD gene therapy at higher dose
All four of these participants were given a relatively low dose of BB-301 in the trial.
A few months ago, Benitec began dosing patients in a second study group that will test a higher dose of the gene therapy. As of late December, the study was still enrolling participants at a site in New York City.
Benitec said it plans to announce interim data from the higher-dose cohort midway through this year. In the meantime, the company is already working on plans for a potentially pivotal trial — a study designed so that positive results could support applications for regulatory approval.
Benitec plans to meet with U.S. regulators in the coming months to go over plans for this pivotal study.
“We look forward to engaging with the U.S. Food and Drug Administration (FDA) in mid-2026 to confirm the BB-301 pivotal study design and continuing to present interim clinical results at future medical conferences,” Banks said.
Banks expressed the company’s appreciation for all those who have taken part or helped to advance clinical testing to date.
“I want to sincerely thank our investigators, our clinical advisors, and — most importantly — the patients and families who have made this progress possible,” Banks said.
