The primary objective of this phase 2/3 study is to evaluate the efficacy of olipudase alfa (recombinant human acid sphingomyelinase) administered intravenously once every 2 weeks for 52 weeks in adult patients with acid sphingomyelinase deficiency (ASMD) by assessing changes in 1) spleen volume as measured by abdominal magnetic resonance imaging (MRI) (and, for the United States [US] only, in association with patient perception related to spleen volume as measured by splenomegaly related score (SRS)); and 2) infiltrative lung disease as measured by the pulmonary function test, diffusing capacity of the lung for carbon monoxide (DLCO).