Real-world safety and effectiveness of alemtuzumab for relapsed or refractory chronic lymphocytic leukaemia: results from postmarketing surveillance in Japan

Background Alemtuzumab is a monoclonal antibody directed against CD52 on T and B lymphocytes and is used to treat lymphoproliferative disorders including chronic lymphocytic leukaemia (CLL). This postmarketing surveillance, as mandated by the Japanese health authorities, investigated the safety and effectiveness of alemtuzumab in Japanese patients receiving alemtuzumab for relapsed/refractory CLL.Methods This was an observational, prospective study conducted in patients with lymphoproliferative disorders who received alemtuzumab in routine clinical practice in Japan between March 2015 and June 2023. Follow-up was for 24 weeks after alemtuzumab administration. Endpoints were adverse drug reactions (ADRs), objective response rate (ORR), progression-free survival (PFS) and overall survival (OS), and factors associated with safety and effectiveness.Results Safety was evaluated in 179 patients with lymphoproliferative disorders (112 males and 67 females; median age 68 years) and effectiveness in 95 with relapsed/refractory CLL. Overall, 138 patients (77.1%) developed an ADR (most commonly cytomegalovirus [CMV]-related events [37.4%]), 100 (55.9%) developed serious ADRs (most commonly CMV-related events [31.3%]), and 93 (52.0%) developed grade >= 3 ADRs (most commonly decreased platelet count [13.4%]). Of 95 patients with relapsed/refractory CLL, 39 (41.1%) had an ORR (15 complete and 24 partial responses). At 24 weeks, PFS and OS rates were 55.5% and 70.0%, respectively. The ORR was significantly associated with Rai classification, performance status, and treatment days or duration.Conclusions This prospective postmarketing surveillance study confirms the effectiveness and manageable safety profile of alemtuzumab for Japanese patients with relapsed/refractory CLL. This postmarketing surveillance in Japanese patients with lymphoproliferative disorders confirms the manageable safety profile of alemtuzumab and demonstrates its effectiveness in treating relapsed/refractory chronic lymphocytic leukaemia in daily clinical practice.