Protalix Biotherapeutics – Preparing To Emerge From Stealth?

Israeli biotech firm Protalix Biotherapeutics Ltd. (PLX: News ) is only months away from announcing the late-stage study results of its lead product candidate prGCD for the treatment of Gaucher (pronounced Go-shay) disease.

Gaucher disease is an inherited genetic disorder, in which patients lack the normal form of the glucocerebrosidase, or GCD enzyme that breaks down specific fat molecules. The lack of this enzyme results in the accumulation of fat in liver, spleen and bone marrow.

The pivotal phase III clinical trial of prGCD, which is currently underway, is a multi-center, randomized, double-blind, parallel group, dose-ranging trial to assess the safety and efficacy of prGCD in 30 naive patients suffering from Gaucher disease. In the trial, patients are selected randomly for one of two dosing arms and receive IV infusions every two weeks for nine months. The primary endpoint of the study is the percent change in spleen volume from baseline, as measured by MRI (Magnetic Resonance Imaging). According to the company, no serious adverse events have been reported in the study. The company is anticipated to announce the phase III trial results of prGCD in the second-half of 2009.

The current standard of care for Gaucher patients is enzyme replacement therapy and Genzyme Inc.’s (GENZ) Cerezyme is currently the only approved enzyme replacement therapy for Gaucher disease.

Though Gaucher is a rare disease, the market for Gaucher drugs is huge due to severity of the symptoms and the chronic nature of the disease. The disease affects fewer than 200,000 people in the United States at any given time. Last year, the drug fetched in sales of $1.2 billion for Genzyme. On Tuesday, Genzyme announced that it is temporarily shutting down one of its manufacturing plants in the U.S. until the end of July to clean up viral contamination.

Protalix’s prGCD, which is also an enzyme replacement therapy, is a plant cell expressed version of the GCD enzyme, developed through the company’s ProCellEx protein expression system. According to the company, plant cells do not carry the risk of infection by human or other animal viruses and as a result the risk of contamination of its products is eliminated.

Unlike prGCD, the existing enzyme replacement therapies like Cerezyme are produced using mammalian cell-based expression systems.

The company believes that prGCD may prove more cost-effective than the currently marketed alternative due to the cost benefits of expression through its ProCellEx protein expression system.

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