Retrospective-prospective Study to Evaluate Treatment Management and Outcomes of Patients With Waldenström's Macroglobulinemia (WM) Treated in Italy According to the Zanubrutinib (Brukinsa®) Compassionate Use Program (CUP) and in Common Practice Following Commercial Approval.

This is a non-interventional, observational, retrospective and prospective multicenter Italian study, to describe treatment management and outcomes of Waldenström's Macroglobulinemia (WM) patients treated according to the Italian Compassionate Use Program (CUP) and receiving zanubrutinib following its commercial approval.

Inclusion Criteria: * Signed and dated informed consent form * Waldenström's macroglobulinemia diagnosis in need of treatment according to ESMO (European Society for Medical Oncology) guideline 2018 * Patients who received Zanubrutinib according to the Italian CUP or in common practice following Zanubrutinib commercial approval * Treatment with zanubrutinib according to current SmPC (Summary of Product Characteristics) * Treatment decision before inclusion into this non-interventional study * Age ≥18 years Exclusion Criteria: * Contraindications according to SmPC for patients with WM * Participation in an interventional clinical trial during zanubrutinib treatment * Patients with disease progression during a BTKi treatment (if pre-treated with BTK, only those intolerants are considered eligible)