Genzyme drugs could be rationed for longer

Production at Genzyme’s Allston Landing site was halted two weeks ago after a virus was detected in a bioreactor used to make the drugs, Cerezyme and Fabrazyme.

The Cambridge company said more time is needed so virus-killing vaporized hydrogen peroxide can be dispersed throughout the plant’s purification area and the cell-culture area. “We’ve decided to sanitize the entire manufacturing facility, not just the cell-culture production area,’’ said spokeswoman Lori Gorski.

In addition, the company said, its inventory of Cerezyme is lower than it first calculated, while demand for the drug is higher.

Genzyme now expects the sales interruption for Cerezyme and Fabrazyme to last six to eight weeks. It previously estimated product shipments would be put on hold for four weeks for Cerezyme and six to eight weeks for Fabrazyme. Both drugs are enzyme replacement therapies. Cerezyme treats Gaucher disease, while Fabrazyme treats Fabry disease.

The company said it hopes to resume full operations at the plant by the end of July, but because of the shutdown, doses will be temporarily rationed for many of the approximately 8,000 patients worldwide who use one of the drugs. The treatments, given intravenously about every other week, cost $200,000 a year per patient, on average.

A prolonged supply shortage means some patients may have to take smaller doses for slightly longer than they otherwise would have, Genzyme officials acknowledged.

Citing the longer sales interruption, Mark Schoenebaum, senior biotechnology analyst at Deutsche Bank, yesterday boosted his forecast of Genzyme’s revenue shortfall stemming from the virus to $245 million, up from an earlier forecast of $100 million. The incident will shave 23 to 49 cents off the company’s earnings per share, up from the 17 to 35 cents previously forecast, Schoenebaum estimated.

“This is the most important issue going on for Genzyme right now,’’ said Schoenebaum, who was conferring with company officials at the Allston plant yesterday. “They seem to be doing everything they can. If they can get it fixed, it would be a one-time event.’’

In a progress report yesterday, Genzyme said regulatory officials in the United States and Europe have given the company approval to distribute stockpiles of Cerezyme and Fabrazyme in its inventory. Genzyme first had to prove to the Food and Drug Administration and the European Medicines Agency that the drugs had been thoroughly tested to assure there were no traces of the virus, Vesivirus 2117, found in the plant. While the virus is not harmful to humans, it could affect the growth of cells used to make the drugs.

The company has organized a group of specialist physicians in the United States to recommend dosing guidelines for doctors who administer the drugs, while the European regulatory agency has made its own recommendations.

In general, for Cerezyme, doctors on both continents are being asked to give priority to children, adolescents, and adults with active Gaucher disease progression, while other adult patients will get half their normal doses every two weeks or their normal doses every four weeks until regular shipments can be resumed this fall.

For Fabrazyme, meanwhile, European regulators have asked that priority be given to children, adolescents, and adult males, who tend to have more severe cases of the disorder than women. US specialists have yet to issue guidance for rationing Fabrazyme.

Carrie Ostrea, 40, a Texas mother of a 10-month-old daughter with Gaucher disease, said she has been in contact with Genzyme daily about the production shutdown, but wasn’t aware of the longer supply interruption. So far, Ostrea said, her daughter has received her full supply of Cerezyme, and she is hopeful that will continue.

“Of course I’m concerned’’ about the supply problems, Ostrea said. “But I want to hear what the plan is. We need to hear what they’re going to do before we begin freaking out.’’

Robert Weisman can be reached at weisman@globe.com.