Genzyme, a biotech company, said that the FDA has rejected its request to sell Myozyme, a medicine to treat a rare affliction called Pompe disease, that is made at a factory in Allston, Massachusetts. Myozyme is already approved in the U.S., made at a smaller plant in Framingham, Mass. The FDA said that the new version should be considered a different product and requires clinical data to show it's safe and effective in enough patients before going to market. That will require another application for approval.

The bar likely wouldn't be so high if Myozyme was a typical pill. But the concern with biotech drugs, which are made by living organisms rather than mixing batches of chemicals, is that they are harder to replicate. Biotech companies have been calling for clinical trials to prove that generic versions of band-name biotech drugs are safe and effective, a higher bar than the typical process for generic approval. That sounds a lot like what the FDA just called for on the product made in the Allston plant, even though that one is from original manufacturer.

Pompe disease is a rare inherited disease and often fatal disorder that disables the heart and the muscles. It is caused by mutations in a gene that makes an enzyme called alpha-glucosidase (GAA) which is used by the body to break down glycogen leading to accumulation of glycogen everywhere in the body especially the cells of the heart and muscles. The discovery of the GAA gene has led to the development of an enzyme replacement therapy, a drug called alglucosidase alfa (Myozyme) which in infantile-onset patients, to decrease heart size, maintain normal heart function, improve muscle function, tone, and strength, and reduce glycogen accumulation.

To get more information, please go to: www.ninds.nih.gov/disorders/pompe/pompe.htm