Pfizer is moving forward in the race to find treatments for Duchenne muscular dystrophy (DMD), announcing enrollment of the first patient in a Phase II trial testing the effect on the disease of an experimental monoclonal antibody.

Pfizer’s fast-track-designated orphan drug candidate will be evaluated for safety, tolerability and efficacy in boys ages 6 to 10 years diagnosed with DMD, regardless of genotype, Pfizer said.

The experimental drug — an anti-myostatin monoclonal antibody — blocks the activity of myostatin, a muscle protein that helps control muscle growth. That mechanism is believed to potentially increase muscle mass and function in boys with the wasting disease.

The trial represents a different angle of attack on DMD treatment, as Prosensa, Sarepta Therapeutics and PTC Therapeutics press ahead with confirmatory studies and application plans for their remedies.PTC Therapeutics was first out of gate this month, providing the DMD community with the first commercially available treatment. The company launched its Translarna (ataluren) in Germany after conditional approval for marketing in the EU states was granted by the European Commission in August. A Phase III confirmatory trial is underway for Translarma, which treats the 13% of DMD patients presenting a nonsense mutation. Translarma is a protein restoration therapy that enables the formation of a functioning dystrophin protein.


Prosensa and Sarepta are pursuing exon-skipping therapies, which correct for mutations in the dystrophin gene by skipping exons—or gene sections—a process that restores the gene’s ability to make the dystrophin protein. Dutch biotech firm Prosensa, scooped up by BioMarin last month, commenced a rolling NDA filing with FDA in October for its breakthrough-therapy-designated drisapersen. Sarepta, whose plans for a year-end submission of eteplirsen were set back when FDA requested more data, is pursuing confirmatory studies and plans a mid-to-late-2015 filing in the US.

The DMD candidates have all benefited from steadfast activism by patient advocates and other stakeholders. The Parent Project Muscular Dystrophy (PPMD), for example, even worked with FDA to draft guidance on engaging patients and families in trials. Most recently, the Duchenne-focused PPMD teamed up with biotech Solid Ventures and researcher SRI International to develop a “Solid Suit” wearable device designed to preserve muscle function.