Safety Study of rhASM Enzyme Replacement Therapy in Adults With Acid Sphingomyelinase Deficiency (Niemann-Pick Disease)

Inclusion Criteria: * Signed, informed consent by the patient or legal guardian prior to performing any study-related procedures; * Have ≤ 0.2 nmol/hr/mg protein ASM activity in peripheral leukocytes, as measured by the reference laboratory; * Have a diffusing capacity (DLco) \> 30% of the predicted normal value; * Have a spleen volume ≥ 2x normal * Female patients of childbearing potential must have a serum pregnancy test negative for β-hCG and agree to use a reliable birth control method for the duration of the study. Exclusion Criteria: * Is pregnant or lactating; * Has received an investigational drug within 30 days prior to study enrollment; * Has a medical condition, including serious intercurrent illness, active hepatitis B or C or human immunodeficiency virus (HIV) infection, cirrhosis, \> stage 3 liver fibrosis, INR \>1.5, platelet count \< 60.0x10\^3/µL, significant cardiac disease (e.g. pulmonary artery pressure \> 40 mm Hg, moderate or severe valvular dysfunction, or \< 40% left ventricular ejection fraction by echocardiography (ECHO)), or any other extenuating circumstances that may significantly interfere with study compliance including all prescribed evaluations and follow-up activities; * Has had a major organ transplant (e.g. bone marrow or liver); * Has had a total splenectomy; * Has an alanine aminotransferase (ALT) or aspartate aminotransferase (AST) value \>250 IU/L or a total bilirubin \>3.6 mg/dL; * Is unwilling or unable to avoid the use of alcohol, medications that may decrease rhASM activity, medications or herbal supplements that may cause or prolong bleeding, and the use of medications or herbal supplements with potential hepatoxicity within 14 days prior to and 28 days afte the rhASM infusion.