Zanubrutinib Treatment in Patients With IgM Monoclonal Gammopathy and Antri-MAG Related Polyneuropathy

Inclusion Criteria: * Able to provide written informed consent and understand and comply with the requirements of the study * Demyelinating PNP defined by the European Federation of Neurological Societies/Peripheral Nerve Society guideline on management of paraproteinemic demyelinating neuropathies (84) * Functional impairment; defined as an INCAT disability score (INCATds) of ≥2 * Age ≥ 18 years * IgM MGUS, defined as the presence of an IgM M-protein (detectable but \< 30 g/L) AND elevated total IgM level in serum * Presence of anti MAG antibodies ≥ 10.000 titer units, measured with the Bühlmann ELISA * Eastern Cooperative Oncology Group (ECOG) performance score 0, 1, or 2 (85) * Adequate hematological laboratory values defined as hemoglobin ≥ 6.0 mmol/L, neutrophils \> 1.0 × 109/L and platelets \> 100 × 109/L * Adequate hepatic and renal function laboratory values defined as aspartate transaminase (ASAT)/ alanine aminotransferase (ALAT) \< 3 × upper limit of normal (ULN), bilirubin \< 1.5× ULN and creatinine clearance ≥ 30 ml/min * Patients with hypertension can only be enrolled when blood pressure is adequately treated, defined as systolic blood pressure of \<140 mmHg and diastolic blood pressure of \<90 mmHg at screening * No history of severe bleeding disorder such as hemophilia A, hemophilia B, von Willebrand disease, or history of spontaneous bleeding requiring blood transfusion or other medical intervention * Previous treatment with intravenous immunoglobulins is all…