Myostatin Blocker To Be Tested in DMD

Pfizer will test its experimental drug PF-06252616 in ambulatory boys with Duchenne MD at multiple sites in the U.S. and elsewhere

Article Highlights:
  • PF-06252616 is an experimental compound designed to block the myostatin protein, a natural limiter of muscle growth.
  • MDA has long supported myostatin inhibition as a potential strategy for the treatment of Duchenne muscular dystrophy and other muscular dystrophies.
by Margaret Wahl on December 22, 2014 - 3:52pm

Multinational pharmaceutical comany Pfizer recently opened a phase 2 study of an experimental compound that may be beneficial in Duchenne muscular dystrophy (DMD) through its ability to block myostatin, a naturally occurring protein that is known to limit muscle growth.

The Pfizer drug, dubbed PF-06252616, is a laboratory-engineered compound designed to stick to and inhibit myostatin, possibly improving muscle strength and function. The drug is delivered by intravenous infusion and will be tested against a placebo in approximately 105 boys with DMD starting at four U.S. sites. Additional U.S. sites and sites in Canada, Europe and Japan are slated to open by April 2015.  

Myostatin inhibition is an MDA-supported strategy

MDA has been a leader in the development of myostatin blocking (also called myostatin "inhibition") as a strategy to treat several forms of muscular dystrophy, particularly DMD but possibly also Becker muscular dystrophy (BMD), limb-girdle muscular dystrophy (LGMD) and others.

Although there is much laboratory evidence that myostatin inhibition can improve muscle health, drug development in this area has been challenging. Two earlier compounds,  both developed with MDA support, have been somewhat disappointing in clinical trials.

In 2008, development  of an experimental myostatin blocker called MYO-029 was halted after the compound was found to be safe and well tolerated but not to improve strength or function in patients with BMD, LGMD and facioscapulohumeral muscular dystrophy (FSHD). And in 2013, efforts to develop myostatin inhibitor ACE-031 were stopped because of concerns about dilated blood vessels and minor bleeding in boys with DMD who received it.

In a December 2014 communication, Pfizer said, "Based on the proposed mechanism of action of PF-06252616, there is the potential to increase muscle mass and function in boys with DMD who have evidence of reduced muscle mass. Prelinical [laboratory] evidence of increased muscle size and function has been demonstrated in mice and nonhuman primates. [A] phase 1 study of PF-06252616 in healthy adults is in the process of being reported."

About the phase 2 trial PF-0625616 in DMD

The new trial will evaluate safety, tolerability, effectiveness, pharmacokinetics (what the body does to a drug) and pharmacodynamics (what the drug does to the body) of PF-0625616 in boys with DMD who meet study criteria.

 Participants must:

  • have a diagnosis of DMD, confirmed by medical history and genetic testing;
  • be at least 6 years old but less than 10 years old;
  • be able to walk and climb stairs;
  • have been on corticosteroids for a minimum of six months prior to joining the study; and
  • meet additional criteria.

The study will have two periods, each lasting 48 weeks. Participants will be randomly assigned to one of three groups. Group 1 will receive PF-0625616 by intravenous infusion in period 1 and during period 2. Group 2 will also receive PF-0625616 during period 1 but will switch to placebo infusions in period 2. Group 3 will receive placebo infusions during period 1 and then receive PF-0625616 during period 2. With this study design, all participants will receive the experimental drug for at least some portion of the trial.

Neither the participants, their families, nor the investigators will know which group a particular patient was enrolled in until after the study has been completed.

The drug or placebo will be given as a two-hour infusion every four weeks. The dosage level of PF-0625616 may increase every 16 weeks, depending on how welll tolerated and safe the drug is.

The trial requires monthly site visits, a number of MRI scans and frequent tests of strength, walking and stair climbing. At this time, there are three sites open in Baltimore and one in Cincinnati. Pfizer has offered to help with expenses related to travel and accommodations.

To participate

For details and updated contact information, see A Phase 2 Study to Evaluate the Safety, Efficacy, Pharmacokinetics and Pharmacodynamics of PF-06252616 in Duchenne Muscular Dystrophy; or enter NCT02310763 in the search box at You can also call Pfizer at (800) 718-1021.



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