Benitec Begins Early Study of BB-301 Gene Therapy for OPMD

Benitec Biopharma has begun the first study to support the start of clinical trials of BB-301, a potential gene therapy for people with oculopharyngeal muscular dystrophy (OPMD).

The BB-301 Tissue Transduction Study is the first of three studies to be conducted in large animals, with the overall goal of providing data to submit an investigational new drug application to the U.S. Food and Drug Administration, a mandatory step to conduct clinical trials.

“Through our continued focus on the validation and optimization of the non-clinical and potential clinical attributes of BB-301 for the treatment of OPMD, our team has an unprecedented opportunity to develop a novel genetic medicine that could facilitate clinically meaningful patient benefit,” Jerel A. Banks, MD, PhD, Benitec’s executive chairman and CEO, said in a press release.

The primary goal of the eight-week long study is to confirm whether BB-301 can be delivered efficiently via an injection directly into the muscle at specific sites in the pharynx (the upper part of the throat, just behind the mouth) using an open surgical procedure. Benitec expects the new method of delivering BB-301 to significantly improve a physician’s ability to accurately administer the medication to the muscles most affected in OPMD.

Using beagle dogs, the company also aims to confirm the optimal treatment doses to be tested in clinical studies, and to facilitate the observation of crucial toxicology data-points. Preliminary data are expected late this year or in early 2021.

OPMD is caused by a faulty PABPN1 gene, leading to a protein that forms insoluble clumps associated with muscle weakness.

BB-301 uses a modified and harmless adeno-associated virus (AAV) to deliver a DNA-directed RNA interference (ddRNAi) directly into cells. The ddRNAi package suppresses production of the mutant PABPN1 protein while providing a source of normal, or wild-type, protein.

This approach to is known as “silence and replace.” According to Benitec, the strategy has the potential to correct alterations in target tissues and improve outcomes for people with OPMD.

BB-301 has received orphan drug status in the U.S. and the European Union for the treatment of OPMD.

Prior studies in animals supported the efficacy of BB-301 when delivered via intramuscular injection. A study in mice showed that the same approach decreased the amount of PABPN1 aggregates, restored muscle strength, and eased muscle scarring.