Observational Study Evaluating the Efficacy and Safety of Zanubrutinib in Participants With Waldenström Macroglobulinemia

Inclusion Criteria:

• Clinical and definitive histologic diagnosis of WM

• Measurable disease, as defined by a serum immunoglobulin M (IgM) level > 0.5 g/dL atthe time of zanubrutinib initiation

• Started treatment with zanubrutinib, has been treated with zanubrutinib, or isplanned to be prescribed zanubrutinib for the treatment of WM

• Bone marrow specimens with central MYD88 test results of:

1. Cohort 1: MYD88 L265P mutation; enrollment of TN participants will be stoppedin each racial and ethnic participant group when the required numbers ofparticipants in the group are met

2. Cohort 2: non-L265P MYD88 mutation(s) and MYD88WT

Exclusion Criteria:

• Evidence of disease transformation before the first dose of zanubrutinib

• Evidence of other non-Hodgkin Lymphoma (NHL) subtypes

• Prior or concurrent active malignancy ≤ 2 years before the first dose ofzanubrutinib, except for malignancies that, in the investigator's opinion, will notobscure the interpretation of safety or efficacy results

• Concurrent participation in another therapeutic clinical study while receivingzanubrutinib, although the participant may be eligible depending on the status ofthe interventional study after discussion with the Medical Monitor or designee on anindividual basis