The Food and Drug Administration has halted plans by biotechnology company PepGen to begin clinical testing of an experimental treatment for a rare kind of muscular dystrophy.
PepGen said Tuesday the agency had placed a clinical hold on a planned Phase 1 trial for the treatment, which is being developed for an inherited muscle-wasting condition known as myotonic dystrophy type 1, or DM1. The FDA will detail the reasons for its decision in an official letter within 30 days, PepGen said.
The biotech’s shares fell about 8%, to $14.50 apiece, in early market trading on Wednesday.
“We are disappointed to receive a clinical hold notice” and “will work closely with the FDA to lift the hold as quickly as possible,” said PepGen CEO James McArthur in a statement.
PepGen is developing an oligonucleotide-based therapy that’s meant to address the underlying genetic defect in patients with DM1. The progressive condition affects an estimated 40,000 people in the U.S. and causes a variety of mental and physical disabilities and, often, an early death.
PepGen disclosed preclinical results for its drug, dubbed PGN-EDODM1, in December, and anticipated beginning a Phase 1 trial in the first half of the year. Despite the clinical hold, PepGen is still expecting study results next year, and a Phase 2 study in Canada evaluating a different drug for Duchenne muscular dystrophy isn’t impacted.
While PepGen doesn’t yet know why the FDA halted testing, the company has become the latest RNA drug developer to face a delay before the start of a Phase 1 trial. In recent years, the agency has paused initial study requests from Sarepta Therapeutics, Dyne Therapeutics, Entrada Therapeutics and Avidity Biosciences, Stifel analyst Paul Matteis wrote in a note to clients Tuesday. Two of those holds were resolved and two are ongoing.
One key question that may be facing all of them, Matteis wrote, is their “therapeutic index,” or the range of doses at which they can be safely and effectively administered. The types of drugs, known as peptide conjugates, “are highly potent for muscle delivery but also go to other regions of the body,” he wrote.
“That said, there's a lot of opacity here, and we can't rule out either that this clinical hold could be more problematic,” Matteis added, such as “raising a specific FDA concern that's hard to disprove” or requiring the company to generate more preclinical data.