The purpose of this study is to compare and evaluate the efficacy and safety of ISU302, an investigational product, and Cerezyme®, comparator, for Type 1 Gaucher Disease patients

Inclusion Criteria:

• The subjects have a diagnosis of Type I Gaucher Disease
• Subjects between 2 years old and 75 years old
• Subjects documented with glucocerebrosidase deficiency
• Subjects with splenomegaly (as indicated by CT volumetric analysis as 5 times over than the standard size (0.2% of total body weight in kilograms))
• A hemoglobin concentration level:Male > 12 years of age <12.0 g/dL Female>12 years of age<11.0 g/dL Child > 2 years of age and <12 years of age <10.5 g/dL
• Platelet count of < 120,000 / ㎣
• Treatment-naive to enzyme replacement therapy (ERT) or treatment- experienced subjects who have not received ERT in the 12 months before screening and antibody test result is negative
• Treatment naive to substrate reduction therapy (SRT) or treatment- experienced subjects who have not received SRT in the 12 months before screening
• Subjects or their spouses who provide consent to use one of following contraception methods, or women in menopause. (In this case, menopause is defined as a period after 12 months from the last menstruation)
• Condoms, sponge, foams, jellies, diaphragm, or intrauterine device (Spouse or patient who had vasectomy or tubal ligation/ hysterectomy)
• Total abstinence from sexual intercourse: Female patient using oral contraceptives must use other contraception method (barrier method) also during the trial period and after the completion of trial as well as up to 90 days from the conclusion of trial.
• The subject or their legal representative has signed the informed consent.

Exclusion Criteria:

• Treatment with any investigational product in 90 days before study entry
• Partial or total splenectomy
• Subjects who have a serious concurrent disease like infection or who abuse addictive drug and substances.
• Pregnant and/or breast-feeding women
• Presence of Hepatitis B surface antigen or Hepatitis C or the patients show positive reaction to human immunodeficiency virus (HIV) type1
• Subjects with a history of allergic reaction to Imiglucerase
• Subjects with a history of severe pulmonary hypertension caused by Gaucher Disease
• Any subject whom the investigator or the sub investigator considers as inad equate for this trial