March 09, 2026-
Benitec Biopharma reported promising interim clinical data from its ongoing Phase 1b/2a study of the AAV9 gene therapy BB-301 for the treatment of oculopharyngeal muscular dystrophy (OPMD), a rare genetic disorder that commonly leads to severe swallowing difficulties known as dysphagia.
The early-stage clinical trial is evaluating intramuscular administration of the AAV9 gene therapy in patients with moderate dysphagia caused by OPMD. According to the company, both low-dose and high-dose BB-301 treatments demonstrated clinically meaningful improvements in measures of swallowing function, including throat closure, throat emptying, and overall dysphagic symptom burden.
In the study, patients treated with the low-dose AAV9 gene therapy experienced durable improvements in swallowing function, with both clinical and radiographic benefits continuing to deepen two years after treatment. Researchers reported that all study completers in the low-dose cohort met the criteria for responders based on improvements across key functional and patient-reported assessments.
The first patient treated with the high-dose BB-301 AAV9 gene therapy demonstrated an especially strong early response. At the three-month interim assessment, the high-dose treatment showed significantly greater improvements in swallowing metrics compared with the low-dose therapy in patients with comparable baseline disease severity. Reductions in dysphagic symptom burden reached approximately 68% with the high dose, compared with about 7% improvement in the low-dose group.
The ongoing Phase 1b/2a trial is an open-label dose-escalation study designed to evaluate the safety and clinical activity of the AAV9 gene therapy in OPMD patients. Investigators are assessing treatment outcomes using several validated measures of swallowing function, including the Sydney Swallow Questionnaire and radiographic imaging techniques that evaluate throat closure and residue after swallowing.
BB-301 uses Benitec’s proprietary DNA-directed RNA interference (ddRNAi) “silence and replace” approach, delivered via an AAV9 vector, to address the underlying genetic cause of OPMD. The therapy simultaneously suppresses the mutant PABPN1 gene responsible for the disease while replacing it with a functional version of the protein.
Currently, no approved treatments exist for dysphagia in OPMD, making BB-301 the only clinical-stage therapy specifically designed to treat swallowing impairment in these patients. The interim data were presented at the 2026 Muscular Dystrophy Association Clinical and Scientific Conference in Orlando.
BB-301 has received Orphan Drug and Fast Track designations from the FDA, as well as Orphan Drug status from the European Medicines Agency, supporting its continued development as a potential disease-modifying AAV gene therapy for OPMD.
