Benitec Reports Positive Interim Results for BB-301 in Oculopharyngeal Muscular Dsytrophy

Benitec Biopharma reported that all patients treated with either the high or low dose of BB-301, an investigational gene therapy for oculopharyngeal muscular dystrophy (OPMD), met formal response criteria in interim phase 1b/2a trial data (NCT06185673). The company also reported no serious adverse events (AEs) across either dose cohort.¹

Jerel A. Banks, MD, PhD, executive chairman and chief executive officer of Benitec, said the new data “reinforces our conviction in the program and the potential to establish a new treatment paradigm for patients suffering from OPMD-related dysphagia.” The company said it is advancing toward a pivotal study it expects to begin in mid-2027.¹

The data come from an open-label, dose-escalation phase 1b/2a trial evaluating BB-301, a one-time gene therapy injected directly into the swallowing muscles of the throat. BB-301 uses a modified AAV9 vector carrying a single construct that simultaneously silences mutant PABPN1, the gene that causes OPMD, and replaces it with a functional, codon-optimized copy, an approach the company calls “Silence and Replace.” The full dataset was accepted as a late-breaking poster at the European Society of Gene and Cell Therapy (ESGCT) Annual Congress.

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The trial has treated 9 patients: 6 in a low-dose cohort, all of whom have now reached the study's final 12-month follow-up timepoint, and 3 in a high-dose cohort, with follow-up ranging from 3 to 9 months. All 9 patients met the trial's formal responder criteria, and no serious AEs have occurred in either cohort to date.

At the month 3 timepoint, the only point where both cohorts have been directly compared, a larger proportion of high-dose patients met statistical response criteria on throat-emptying ability (100% vs 67% with low dose) and on a timed-drinking test of functional swallowing capacity (67% vs 17%). Total Sydney Swallow Questionnaire scores and throat-closing ability showed equivalent response rates between the 2 doses (100% and 67%, respectively, in both cohorts). The company did not report P values, confidence intervals, or raw patient counts for these comparisons, and the cohorts remain small, at 3 and 6 patients.

Early data: the first low-dose patient, July 2024

Benitec first reported outcomes for BB-301 in July 2024, when the first treated patient reached the 180-day post-dose timepoint. At that visit, videofluoroscopic measures of swallowing showed reduced pharyngeal residue across multiple food consistencies compared with the patient's own pre-treatment natural history data, and the patient's Sydney Swallow Questionnaire score improved from a 9-month pre-dose average of 1136 to 820. The company reported no serious AEs in the first 2 patients treated at that time, after earlier in 2024 noting cases of gastroesophageal reflux disease following treatment.²

Cohort 1: 12- and 24-month data, January 2026

By January 2026, Benitec reported that the first 4 patients in the low-dose cohort had completed 12-month follow-up, all meeting responder criteria, and that the first patient treated had reached 24 months. In that patient, throat-closing ability during swallowing improved 27% at 12 months and was maintained at 24 months, while swallowing efficiency and Sydney Swallow Questionnaire scores continued to improve between the 2 timepoints, with the questionnaire score improving 64% at 12 months and 78% at 24 months.³

The newly reported data extend the low-dose cohort to its full 12-month follow-up across all 6 patients and add the trial's first results from the high-dose cohort.¹

REFERENCES
1. Benitec Biopharma announces positive interim phase 1b/2a results for high dose BB-301 and continued durable improvements for low dose BB-301. News release. Benitec Biopharma. Published October 28, 2026. Accessed October 29, 2026. https://www.biospace.com/press-releases/benitec-biopharma-announces-positive-interim-phase-1b-2a-results-for-high-dose-bb-301-and-continued-durable-improvements-for-low-dose-bb-301
2. Benitec Biopharma reports continued durable improvements in the radiographic assessments of swallowing efficiency and the subject-reported outcome instrument at the 180-day timepoint for first OPMD subject treated with low-dose BB-301 in Phase 1b/2a study. News release. Benitec Biopharma. Published July 15, 2024. Accessed October 29, 2026. https://www.benitec.com/for-investors/news-events/press-releases/detail/117/benitec-biopharma-reports-continued-durable-improvements-in-the-radiographic-assessments-of-swallowing-efficiency-and-the-subject-reported-outcome-instrument-at-the-180-day-timepoint-for-first-opmd-subject-treated-with-low-dose-bb-301-in-phase-1b2a-study
3. Benitec Biopharma provides positive long-term clinical study results for BB-301 Phase 1b/2a clinical trial demonstrating robust efficacy and continued durability of response. News release. Benitec Biopharma. Published January 11, 2026. Accessed October 29, 2026. https://www.benitec.com/for-investors/news-events/press-releases/detail/141/benitec-biopharma-provides-positive-long-term-clinical-study-results-for-bb-301-phase-1b2a-clinical-trial-demonstrating-robust-efficacy-and-continued-durability-of-response