UPDATE 3-FDA speeds access to Protalix, Shire Gaucher drugs

* FDA asks Protalix to speed access to Gaucher drug

* FDA says Protalix drug meets expanded access criteria

* FDA action to offset likely shortages of Genzyme drug

* Protalix shares up 8 percent (Updates with comment from analyst, Protalix, Genzyme)

By Toni Clarke

BOSTON, July 6 (Reuters) - The U.S. Food and Drug Administration is moving to speed up access to experimental drugs for Gaucher disease to help offset likely shortages of Cerezyme, the top-selling drug made by Genzyme Corp GENZ.O.

Biotechnology company Protalix BioTherapeutics Inc PLX.A and Shire Plc SHP.LSHPGY.O said on Monday they have been approached by the FDA to expand access to their experimental drugs for the rare but serious disorder.

Patients with Gaucher are deficient in an enzyme that breaks down a certain type of fat molecule. Fatty cells accumulate in different parts of the body, including the spleen, liver and bone marrow.

The shares of Protalix, which is based in Israel, rose 8.2 percent to close at $4.88 on the American Stock Exchange. Genzyme’s shares were up 30 cents, or 0.6 percent, at $55.05. Shire stock rose 1.8 percent to end at $41.03.

Genzyme, which makes Cerezyme, the world’s leading treatment for Gaucher disease, recently announced it would shut down its plant in Boston after a virus halted production of Cerezyme and Fabrazyme, its treatment for Fabry disease, another rare condition.

Protalix said the FDA asked the company to consider submitting a treatment protocol that would allow use of its treatment prGCD under an expanded access program. Under this program, a treatment protocol may be submitted for a drug that has not yet been approved, but is in development for a serious disease for which no other therapy is available.

The company is discussing the parameters of a proposed treatment protocol that would allow an increased number of patients with Gaucher disease to have access to prGCD, which is in late-stage development.

Shire said it has already filed a treatment protocol for its drug velaglucerase alfa. Both Shire and Protalix said they would provide their drugs free of charge.

David Aviezer, the chief executive of Protalix, expects approval of the treatment protocol within the next 60 days. He said the company is on track to file an application for full approval of the drug by the end of this year.

Some analysts said the FDA’s action gives a good indication of how the agency views the drug.

“We view the FDA’s request as clearly positive for Protalix, as it indicates FDA’s comfort with prGCD’s safety and efficacy data, and increases the likelihood of ultimate prGCD approval,” said Brian Abrahams, an analyst at Oppenheimer & Co.

Genzyme expects its Boston plant to be on line again in late July, with shortages of Cerezyme following the depletion of inventories expected to hit in August. Shortages of Fabrazyme will likely start to be seen in October.

Cerezyme, an enzyme replacement therapy, is Genzyme’s biggest-selling product and, at $200,000 a year, is one of the world’s most expensive drugs. Cerezyme and Fabrazyme represented about 37 percent of the company’s 2008 revenue of $4.6 billion.

“The fact that the FDA has reached out to Protalix is not unexpected,” said Geoff McDonough, senior vice president of the Genetic Diseases business at Genzyme. “They would be looking at all possible avenues.”

McDonough said some patients on Cerezyme may choose to skip one or two doses rather than switch to another drug. Genzyme said supply will be conserved for infants and people with very severe disease.

“Conserving the equivalent of two doses can probably be done in a way that would not lead to long term impact on their health,” McDonough said. “It is an individual treatment decision for patients and physicians.”

Earlier Genzyme said the virus that affected the Boston plant, known as the Allston plant, is a strain known as Vesivirus 2117 that has not been shown to cause human infection, but is known to interfere with the growth of cells used to produce the drugs.

Unlike Cerezyme, which is made using a transformed Chinese hamster ovary cell line, Protalix makes its drug using a plant cell culture, which if it works, could avoid risks from mammalian viruses. Protalix says it believes it can make a cheaper product that stays in the body longer than Cerezyme. (Reporting by Toni Clarke, editing by Gerald E. McCormick and Andre Grenon)