Over the weekend, drugmaker Genzyme shut down a Massachusetts factory after a virus infected hamster ovary cells used to produce Fabrazyme and Cerezyme, drugs for two rare genetic disorders

Genzyme is the sole supplier of the medicines in the United States. When stocks of the medicines run low in August, patients may have to ration supplies for four to six weeks. Jack Johnson, a 46-year-old Missourian, who takes Fabrazyme, says the shutdown “is a concern for patients . . . but we’ll just have to wait and see how this all plays out.”

The U.S. Food and Drug Administration (FDA) has put shipments of Cerezyme and Fabrazyme on hold while the company conducts DNA tests on its current stockpiles, Genzyme Executive Vice President David Meeker said during a conference call yesterday.  He expects the plant to reopen by the end of July, and supplies to be steady by the end of the year.

This was the second time the company’s production vats have been infected with a virus called Vesivirus 2117, which first hit its facilities in 2008.  In February, the FDA also sent a warning letter to the plant after an inspection uncovered quality problems. However, company representatives said that Genzyme had already addressed the FDA’s concerns in that letter and that they were not linked to the viral infection, which was caused by contamination in a still-unidentified nutrient added to the cell mixture. “Contamination may be transient and we may never identify the source,” Meeker said.

Genzyme's Chief Medical Officer, Richard Moscicki, says the virus was unable to infect human cells during their own laboratory tests. Though the virus is a member of the Calicivirus family known to infect humans, Vesivirus has only “dubious” associations with human disease, says Moscicki.  Alvin Smith, a Calicivirus expert formerly with Oregon State University, and colleagues published a paper in 2006 claiming an association between Vesivirus, hepatitis and liver damage. But the team’s results have since been questioned by Dutch researchers who were unable to replicate them in the Netherlands.

More important to patients is the question of how long the shortages will last.  Cerezyme is used to treat Gaucher’s disease, an enzyme deficiency that can cause osteoporosis and an enlarged spleen or liver.  Fabrazyme is used to treat Fabry disease, another enzyme deficiency, that causes the build-up of fatty acids and oils in the eyes and kidneys along with cardiovascular and nervous system problems.  The diseases affect about 8000 people worldwide. Genzyme’s enzyme replacement therapies cost approximately $200,000 per year.

Rhonda Buyers, CEO of the National Gaucher Foundation, says Genzyme told her group the company is working diligently to keep the plant closure short.

Image of Genzyme headquarters in Cambridge, Mass. courtesy of Tim Pierce via Wikipedia.