Benitec Biopharma Inc. announced continued durable improvements in the radiographic assessments of swallowing efficiency and the subject-reported outcome instrument as assessed at the 180-day timepoint following the administration of the low-dose of BB-301 to the study?s first subject (Subject 1) treated in the BB-301 Phase 1b/2a single-arm, open-label, sequential, dose-escalation cohort study (NCT06185673) in Oculopharyngeal Muscular Dystrophy (OPMD). BB-301 has been granted Orphan Drug designation by the U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA) Committee for Orphan Medicinal Products (COMP). The current interim clinical study update focuses principally on the 180-day results of the videofluoroscopic swallowing study (?VFSS?) assessments of Total Pharyngeal Residue (?TPR?, i.e., the amount of solid food or liquid material remaining in the pharynx after the first swallow) and the Subject-Reported Outcome Instrument (i.e., the Sydney Swallow Questionnaire or ?SSQ?) as the Key Opinion Leaders (KOLs) participating in the recent BB-301 Research and Development Day webcast in April 2024 highlighted the Total Pharyngeal Residue and the SSQ as the central markers of value for the long-term evaluation of clinically meaningful improvement in subjects diagnosed with OPMD.

Additionally, as the formal statistical plan for the BB-301 Phase 1b/2a clinical study comprises comparisons of the average pre-dose assessments to the respective average 365-day post-dose assessments for each subject, the interim clinical study update focuses on these specific quantitative comparisons. Benitec plans to provide additional analyses of the interim clinical study data at upcoming medical conferences and company-sponsored Research and Development-focused webcasts in the first quarter of calendar 2025. Previously Announced 90-Day Post-Dose Interim Clinical Study Results: At the 90-day post-dose assessment following the administration of the low-dose of BB-301, Subject 1 demonstrated improvements in key VFSS assessments which correlated with the observation of similar levels of improvement in the SSQ as compared to the pre-dose average values recorded for Subject 1 during the OPMD Natural History Study, indicating an improvement in swallowing function as reported by Subject 1. Newly Reported 180-Day Post-Dose Interim Clinical Study Results: The post-dose average values for TPR remained meaningfully reduced (i.e., smaller amounts of solid food and liquid material remained in the pharynx after the completion of the first swallow) at the 180-day post-dose assessment following the administration of the low-dose of gene therapy BB-301 as compared to the pre-dose average values recorded for Subject 1 during the OPMD Natural History Study.

Critically, for three of the four food types evaluated during the radiographic swallowing study assessments for Subject 1, the post-dose average TPR values were lower at the 180-day post-dose assessments than at any point during the 9-month pre-dose observation period comprising the OPMD Natural History Study, with the post-dose average TPR value for the fourth food type being similar to the lowest TPR value observed at any point during the 9-month pre-dose observation period of the OPMD Natural History Study. The Total Score recorded for the Subject-Reported SSQ also demonstrated continued reductions in the Subject?s dysphagic symptoms (i.e., improvements in the Subject?s ability to swallow) at the 180-day post-dose timepoint, with the Total SSQ Score continuing to decline and remaining meaningfully reduced as compared to the pre-dose average value recorded for Subject 1 during the OPMD Natural History Study, indicating a greater improvement in swallowing function as reported by Subject 1. Importantly, similar to the results observed for the VFSS assessments of TPR, the post-dose average Total SSQ Score was lower at the 180-day post-dose timepoint than at any point during the 9-month pre-dose assessment period of the OPMD Natural History Study.