Safety and effectiveness of lenalidomide in Japanese patients with relapsed/refractory ATLL: post-marketing surveillance

Lenalidomide is an oral immunomodulatory agent approved for the treatment of relapsed/refractory adult T-cell leukemia/lymphoma (ATLL) in Japan. Post-marketing surveillance (PMS) was conducted to confirm its safety and effectiveness. From April 2017 until April 2020, safety data were obtained for 77 patients and effectiveness data for 65 patients (31.2% of patients had progressive disease as the best response to their most recent prior regimen). Forty-nine patients (63.6%) in the safety analysis set experienced an adverse drug reaction (ADR). Grade ≥ 3 ADRs occurred in 42.9%. The most common Grade ≥ 3 ADRs were neutrophil count decreased/neutropenia and platelet count decreased/thrombocytopenia (11.7% each). Serious ADRs occurred in 26 patients. Five patients had previously received allogeneic hematopoietic stem cell transplantation. Among these, one experienced acute graft versus host disease (GvHD) during lenalidomide administration and two responded to lenalidomide. Effectiveness analysis showed that an objective response was achieved in 29.2% of patients. No statistically significant differences were observed in the objective response rates of patients aged < 70 versus those aged ≥ 70 years (33.3% vs 28.0%, respectively; p = 0.6904). No new safety signals were observed in this PMS, and lenalidomide demonstrated a favorable benefit-risk balance in Japanese patients with ATLL.