Drug for Duchenne MD Clears Phase 1 Study

PTC124, an experimental drug aimed at some 15 percent of boys with Duchenne muscular dystrophy (DMD), is safe and reaches adequate blood levels in healthy test subjects, its developer announced April 11 at the 57th annual meeting of the American Academy of Neurology in Miami Beach, Fla.

PTC Therapeutics of South Plainfield, N.J., developed PTC124 as an experimental compound aimed at genetic defects known as “premature stop codons” or “nonsense mutations,” a type of defect that affects some 15 percent of boys with DMD and some 10 percent of patients with cystic fibrosis. Such flaws (mutations) keep people with these disorders from making full-length, fully functional protein molecules from the affected genes.

PTC124 allows cells to “read through” premature stop codons and make full-length protein molecules.

(Special genetic testing is necessary to determine the type of mutation in DMD. Families can inquire about such testing at their MDA clinic or via www.genetests.org. Search under Laboratory Directory; then Duchenne; then “Testing.” Look at labs that offer “sequencing of entire coding region.”)

MDA research grantee H. Lee Sweeney, a molecular biologist at the University of Pennsylvania, worked with PTC during the laboratory phase of the drug’s development.

This phase 1 human trial was conducted in people without a genetic disease to determine whether PTC124 was safe and could reach adequate concentrations in blood when taken orally. It demonstrated adequate concentrations and safety when taken at doses of up to 50 milligrams per kilogram twice a day for up to 14 days.

PTC is now working with researchers and the Food and Drug Administration to finalize plans for phase 2 studies. These will be conducted in people with DMD and cystic fibrosis.