Shire Plc. (SHPGY) recently presented positive phase III data on its Gaucher disease product, Vpriv. The trial was conducted to study the safety of switching patients from Genzyme’s (GENZ) Cerezyme (imiglucerase) to Vpriv.

Results showed that both adult as well as pediatric patients who switched from Cerezyme to Vpriv did not develop IgG antibodies to Vpriv. This included 3 patients who tested positive for anti-Cerezyme antibodies at screening.

Moreover, it was found that hemoglobin concentration, platelet counts, and liver and spleen volumes remained stable during the one year study, showing safety and maintenance of efficacy during this period.

Shire also presented interim safety data from an ongoing multi-center open-label treatment protocol, which was put in place to provide Vpriv to patients affected by the shortage in supply of Cerezyme. Meanwhile, data from a long-term study showed that patients (n=8) treated with Vpriv achieved four long-term therapeutic goals within 4 years of initiation of treatment.

With Genzyme trying to emerge from its manufacturing issues, which affected the supply of Cerezyme for a major part of 2009, the data presented by Shire should help Vprivto garner share from Cerezyme, which has so far monopolized the Gaucher disease market. Vpriv should also be able to capture a share of the treatment naïve patient population.

Vpriv received approval from the U.S. Food and Drug Administration (FDA) in late February 2010 and is currently under review in the European Union where it was granted accelerated assessment by the European Medicines Agency.

Shire should be in a position to launch Vpriv in the EU by year end. Meanwhile, product launch in other countries should commence in 2011.

We expect competition in the Gaucher disease market to intensify further later this year with the potential approval of Protalix’ BioTherapeutics’ (PLX - Snapshot Report) Uplyso. Protalix has a marketing agreement with Pfizer, Inc. (PFE - Analyst Report)for Uplyso.