Wyeth Pharmaceuticals (NYSE:WYE) has evidence that muscle growth may be as easy as a shot in the arm.

Last month, the drug manufacturer began a phase 1 trial of myo-29, a monoclonal antibody that blocks the production of myostatin, a natural occurring protein in the body. A Wyeth-sponsored study recently published in the New England Journal of Medicine suggests why blocking myostatin may be desirable. At the center of that investigation was a 4-year-old boy with twice the muscle mass and half the body fat of other children his age. The boy has an apparently unique genetic mutation that inhibits myostatin production. From this and earlier research, Wyeth has determined that the protein inhibits muscle growth.

Wyeth believes that by blocking myostatin, myo-29 could have promise in treating muscle-wasting diseases. The firm is focusing first on the possibility that the drug could help alleviate, although not cure, muscular dystrophy. In addition, the medicine may be useful in a host of other areas, including age-related frailty and muscle loss associated with other ailments.

Of course, myo-29 is just starting phase 1 testing, so it is a long, long way from the market. Still, the drug may be more intriguing than most early stage candidates. Since the myostatin-blocking mutation occurs in nature -- and more importantly, in at least one human being -- with as yet no observable negative impact, a treatment that inhibits the protein would seem to be less likely to have toxic side effects. Such problems have a nasty way of derailing promising treatments. At the very least, then, myo-29 appears to have a better-than-average shot at advancing into phase 2. And even limited effectiveness in phase 2 investigations may be more than enough reason to pursue further development.

Wyeth has a long road to travel if myo-29 is to become a commercialized product. In the meantime, though, this is one drug that bears close watching.

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Fool contributor Brian Gorman is a freelance writer living in Chicago, Ill. He does not own shares of any companies mentioned here.