LAUSR

Dear Editor, Despite the introduction of novel front-line therapies including rituximab plus high-dose cytarabine followed by consolidative autologous stem cell transplantation (ASCT) and salvage therapy with bendamustine, lenalidomide or bortezomib, mantle cell lymphoma (MCL) is still considered incurable and most patients experience relapse or refractory (RR) disease. Ibrutinib (Imbruvica R ©) is a firstin-class oral agent that mainly works by inhibiting Bruton’s tyrosine kinase and is considered the standard of care for RR MCL. However, reports for outcomes and safety profiles of ibrutinib treatment in Asian RR MCL patients are limited as MCL accounts for less than 3% of NonHodgkin’s lymphomas in Asia [1, 2]. To evaluate the realworld outcomes of ibrutinib therapy in RR MCL patients in Korea, we performed a retrospective analysis of patients with RRMCL who were treated with ibrutinib from 18 tertiary institutes (details are provided in the Supplementary Materials). A total of 88 patients were analyzed. Their immunophenotypic and cytogenetics features at the time of diagnosis are shown in Supplementary Table S1. 71 (80.7%) patientsweremale. Three (3.4%) patients had blastoid variants MCL. At the time of initial diagnosis, their median age was 67 (range: 40-90) years. A total of 11 (12.5%) patients were classified as stage II and 77 (87.5%) as stage III-IV. All patients received combination chemotherapy with or without rituximab as front-line treatment. Rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) was the most frequently used regimen (n = 59, 67.0%), followed by rituximab plus fractionated cyclophosphamide, vincristine, doxorubicin, and