A Study to Evaluate the Safety and Clinical Activity of Intramuscular Doses of BB-301 Administered to Subjects With Oculopharyngeal Muscular Dystrophy With Dysphagia

Inclusion Criteria: * Subject was previously enrolled in the BNTC-OPMD-NH-001 natural history (NH) study and completed at least 6 months of follow-up in the NH study. * Signed written informed consent prior to the initiation of any study-specific procedures. * Males or females, aged ≥50 to ≤65 years at the time of NH study enrollment, with genetically diagnosed heterozygous OPMD disease (as indicated by 1 of the following allelic classifications: GCN10/GCN12, GCN10/GCN13, GCN10/GCN14, GCN10/GCN15, GCN10/GCN16) OR * Males or females, aged ≤65 years at the time of NH study enrollment, with genetically diagnosed homozygous OPMD disease (as indicated by 1 of the following allelic classifications: GCN12/GCN12, GCN13/GCN13, GCN14/GCN14, GCN15/GCN15, GCN16/GCN16). * Subject is eligible and willing to undergo a surgical dissection of the pharyngeal region with intubation under general anesthesia to administer the study drug. * Subject has moderate dysphagia, defined as pharyngeal area at maximum constriction (PhAMPC) \>2.7%(C2-4)\^2 with natural sips of thin liquid barium or PhAMPC \>2.1%(C2-4)\^2 with teaspoon delivery of moderately thick liquid barium. * Subject is not of childbearing potential, i.e., is postmenopausal (absence of menstrual bleeding for ≥1 year before Baseline, without any other medical reason), or has documented hysterectomy, bilateral salpingectomy, or bilateral oophorectomy OR * Subject or their partner is of childbearing potential and agrees to use 2 highly ef…