BB-301 Shows Improvement in Swallowing Measures in High-Dose Muscular Dystrophy Trial
Key Facts
Benitec Biopharma announced positive interim results for BB-301 in a Phase 1b/2a trial targeting patients with oculopharyngeal muscular dystrophy and moderate dysphagia, according to a company disclosure. The results are part of an open-label, dose-escalation study evaluating the treatment’s safety and clinical activity when administered by intramuscular injection. An earlier comparison after 3 months showed improvement in swallowing measures in one patient who received the high dose, alongside published results for one patient who received the low dose. These figures therefore remain an early signal from a limited sample and do not represent results for the entire high-dose cohort. In a separate update, the company had announced that all three patients in the high-dose cohort had safely received treatment through September 14, 2026.
In the comparison published by the company in March, pharyngeal contraction, measured by pharyngeal area at maximum contraction, improved by about 19% after the high dose, versus about 8% after the low dose. Total pharyngeal clearance also improved by about 44% with the high dose, while the measure declined by about 6% with the low dose. On the vallecular clearance measure, improvement was about 57% with the high dose, versus about 3% with the low dose. The high-dose results published at the time were based on the first patient in the second cohort, while the six patients in the first cohort had reached the 12-month assessment point. These comparisons should not be read as a cohort result for the three patients later treated with the high dose.
Efficacy follow-up includes the Sydney Swallow Questionnaire, along with measures of pharyngeal contraction and residue, including the standardized vallecular residue measure. The company said long-term efficacy trends in the low-dose cohort remained evident after 24 months, including improvement in throat closure and clearance and a reduced burden of dysphagia symptoms. In an earlier disclosure, it said the six patients who completed the first cohort met the formal response criteria, representing a 100% response rate within that cohort. The company said in September that the six patients had completed 12 months of post-treatment follow-up. The reported response rate applies to the low-dose cohort and does not establish a response among all participants in both dose cohorts.
BB-301 targets OPMD, a rare degenerative muscle disorder associated with a mutation in the PABPN1 gene, according to the company. There are currently no approved treatments for the disease, while the company said progressive dysphagia affects 97% of OPMD patients and may be associated with chronic choking, malnutrition, aspiration pneumonia and death. The U.S. Food and Drug Administration granted the drug Fast Track designation for OPMD with dysphagia after reviewing the interim results and responder analysis submitted by the company. Benitec’s program is based on its “silence and replace” platform, which combines RNA interference and gene therapy to silence and replace genes. The company presents the platform as a basis for developing BB-301 in a program targeting a rare disorder for which no approved treatment is available.
On the regulatory front, Benitec said on October 5 that the FDA had requested additional data, including data from a natural history study of the disease. It added that the agency had agreed to review the information on a timeline that would allow the company to confirm the final pivotal study design in the first quarter of 2027. The company plans to begin enrolling patients in that study in mid-2027. This places the current trial results among development steps preceding a pivotal study, while the announced timelines depend on completing the regulatory review and providing the requested data.