Switchover Trial From Imiglucerase to Plant Cell Expressed Recombinant Human Glucocerebrosidase

This is a multi-center, open-label, switchover trial to assess the safety of taliglucerase
alfa in 30 patients with Gaucher disease who are currently being treated with imiglucerase
(Cerezyme®) ERT. Eligible patients will enter a 12-week Stability Evaluation Period to
establish the stability of their disease. Patients with stable disease will then be switched
from their imiglucerase treatment to receive intravenous (IV) infusions of taliglucerase alfa
every two weeks for a total of 20 IV infusions. The dose of taliglucerase alfa will be equal
to each patient's previous imiglucerase dose. The infusions will be administered at the
selected investigational site (clinic/hospital), infusion center, or at home. At the end of
the 9-month treatment period (20 visits, 38 weeks) eligible patients will be offered
enrollment in an open-label extension study.

Inclusion Criteria:

- Males and females, 2 years or older

- Confirmed diagnosis of Gaucher disease by the enzymatic activity assay

- Stable Gaucher disease

- Treatment with imiglucerase (Cerezyme®) for at least 2 years and on a stable
maintenance regimen (dose and regimen unchanged, except for situation of drug
shortage) for at least the last six months

- Able to provide written informed consent

Exclusion Criteria:

- Currently taking another experimental drug for any condition

- History of allergy to carrots

- History of allergy to beta lactam antibiotics

- Previous infusion reaction suspected to be allergic in nature to Cerezyme® or
Ceredase® or receiving premedication to prevent infusion reactions

- Presence of HIV and/or HBsAg and/or hepatitis C infection

- Presence of unresolved anemia due to iron, folic acid or vitamin B12 deficiency

- Presence of any significant comorbidity that could confound the interpretation of the
clinical response to taliglucerase alfa

- Presence of any medical, emotional, behavioral or psychological condition that in the
judgment of the Investigator would interfere with the patient's compliance with the
requirements of the study