Observational retrospective study of the treatment of Waldenström's macroglobulinemia with ibrutinib in routine clinical practice in Spain.

Abstract

Background: Waldenström's macroglobulinemia (WM) is a B-cell neoplasia characterized by the infiltration of lymphoplasmacytic lymphoma cells in the bone marrow and abnormal secretion of IgM paraprotein. Ibrutinib, a Bruton tyrosine kinase inhibitor (BTKi), showed high efficacy in WM clinical trials. However, there is limited real-world data regarding its effectiveness and safety in routine clinical practice.

Objectives: The MACRO study aimed to investigate the clinical, genetic, and demographic characteristics of WM patients treated with ibrutinib-based therapies in Spain. Key secondary objectives included describing effectiveness and safety profile.

Design: Retrospective observational.

Methods: This multicenter, observational, retrospective study included adult patients diagnosed with symptomatic WM treated with ibrutinib since its commercial approval in Spain in 2016. Data were collected from 19 hospitals through retrospective medical chart reviews.

Results: Fifty-two eligible patients were recruited. The median age at the start of ibrutinib treatment was 74 years. Most of patients were male (65.4%) and had an Eastern Cooperative Oncology Group performance status of 0-1 (89.7%). Overall response rate was 92.2%, with a major response rate of 80.5%. Median progression-free survival (PFS) was 57.2 months, and the estimated 2-year overall survival rate was 89.2%. No significant differences in PFS were identified based on the parameters defining risk subgroups, nor did they vary according to treatment line, initial dose, or treatment schedule. Most common adverse events included bleeding (30.8%), diarrhea (23.1%), and infections (15.4%), with most of them being grades 1-2. No new safety signs were identified.

Conclusion: This study presents real-world evidence on the characteristics and outcomes of WM patients treated with ibrutinib in Spain, showing it to be effective with a manageable safety profile consistent with clinical trial results. These findings support ibrutinib as a valuable treatment option for WM in real-world settings.