A Study of Ibrutinib in Combination With Rituximab, in Japanese Participants With Waldenstrom's Macroglobulinemia (WM)

Inclusion Criteria: * Clinicopathological diagnosis of Waldenstrom's Macroglobulinemia (WM) in accordance with the consensus panel of the second International Workshop on Waldenstrom's Macroglobulinemia (IWWM) * Japanese participants with treatment naïve or relapsed/refractory WM * Measurable disease defined as serum monoclonal immunoglobulin M (IgM) greater than (\>) 0.5 gram per deciliter (g/dL) * Symptomatic disease, requiring treatment * Eastern Cooperative Oncology Group (ECOG) performance status of less than or equal to (\<=) 2 * Hematology and biochemical values within protocol-defined limits * Female participants of childbearing potential must have a negative serum pregnancy test at screening and agree to use highly effective methods of contraception while taking study drug. Women of childbearing potential must be practicing a highly effective, preferably user independent method of birth control during treatment with any drug in this study and for up to 12 months after the last dose of rituximab, 1 month after last dose of ibrutinib. Male participants must use an effective barrier method of contraception during the study and after receiving the last dose of ibrutinib, and for up to 12 months after last dose of rituximab if sexually active with a female of childbearing potential * Must sign an informed consent form (ICF) indicating that he or she understands the purpose of, and procedures required for, the study and is willing to participate in the study. Participants…