A Study of Ibrutinib (PCI-32765) in Chinese Participants With Relapse or Refractory Waldenstrom's Macroglobulinemia (WM)

Inclusion Criteria:

* Men and women greater than or equal to (\>=) 18 years of age
* Eastern Cooperative Oncology Group (ECOG) less than or equal to (\<=) 2
* Previously received at least one prior therapy for WM and have had either documented disease progression or had no response to the most recent treatment regimen
* Centrally confirmed clinicopathological diagnosis of WM
* Measurable disease defined as serum monoclonal immunoglobulin M (IgM) \>0.5 gram per deciliter (g/dL)
* Symptomatic disease, requiring treatment
* 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. Female participants of childbearing potential should avoid becoming pregnant while taking ibrutinib and for up to 1 month after the last dose of study drug. Male participants must use an effective barrier method of contraception during the study and for 3 months following the last dose of ibrutinib if sexually active with a female of childbearing potential

Exclusion Criteria:

* Involvement of the central nervous system by WM
* Evidence of disease transformation
* Prior exposure to BTK inhibitors
* Known hypersensitivity reaction to ibrutinib or to the excipients in its formulation
* Received any WM-related therapy \<=30 days prior to first administration of study treatment
* Received a prior allogeneic hematopoietic stem cell transplant
* Plasmapheresis \<35 days prior to the initiation of study drug, except when at least one serum IgM central assessment was performed during the screening period and was \>35 days from the most recent plasmapheresis procedure
* History of other malignancies, except: (a) malignancy treated with curative intent and with no known active disease present for \>=2 years before the first dose of study drug and felt to be at low risk for recurrence by treating physician; (b) adequately treated nonmelanoma skin cancer or lentigo maligna without evidence of disease; (c) adequately treated carcinoma in situ without evidence of disease
* Vaccinated with live, attenuated vaccines within 4 weeks of first dose of study drug
* Infection requiring systemic treatment that was completed \<=14 days before the first dose of study drug
* Bleeding disorders or hemophilia
* Stroke or intracranial hemorrhage within 6 months prior to enrollment
* Infection with human immunodeficiency virus (HIV) or active infection with hepatitis B or hepatitis C
* Major surgery within 4 weeks of first dose of study drug
* Any life-threatening illness, medical condition, or organ system dysfunction that, in the investigator's opinion, could compromise the participant's safety or put the study outcomes at undue risk
* Currently active, clinically significant hepatic impairment Child-Pugh Class B or C according to the Child Pugh classification
* Currently active, clinically significant cardiovascular disease
* Requires or receiving anticoagulation with warfarin or other Vitamin K antagonists
* Unable to swallow capsules or malabsorption syndrome, disease significantly affecting gastrointestinal function, or resection of the stomach or small bowel, symptomatic inflammatory bowel disease or ulcerative colitis, or partial or complete bowel obstruction
* Requires treatment with a strong cytochrome P450 (CYP) 3A inhibitor
* Lactating or pregnant
* Unable to understand the purpose and risks of the study and to provide a signed and dated informed consent form (ICF) and authorization to use protected health information (in accordance with national and local participant privacy regulations)