Yttrium-90 (⁹⁰Y) ibritumomab tiuxetan (Zevalin®) induces long-term durable responses in patients with relapsed or refractory B-cell non-Hodgkin's lymphoma

Aim: Yttrium-90 (⁹⁰Y) ibritumomab tiuxetan (Zevalin®) radioimmunotherapy is an effective treatment for relapsed or refractory B-cell non-Hodgkin's lymphoma (NHL), with overall response rates ranging from 74% to 82%. This retrospective analysis was conducted to determine the number of patients achieving long-term durable responses with ⁹⁰Y ibritumomab tiuxetan treatment. Materials and Methods: The medical records of patients (n = 211) with relapsed, refractory, or transformed indolent CD20+ B-cell NHL who were treated with ⁹⁰Y ibritumomab tiuxetan were reviewed. Time to progression (TTP) of ≥12 months was noted in 78 patients (37%), who were identified as long-term responders and were further characterized. Results: Median age of the long-term responders was 58 years (range, 24-80 years) with 44% over 60 years, and 55% were male. Notably, 59% of patients had received ≥2 prior regimens, 33% had received ≥3 prior regimens, and 37% had failed to respond to immediate prior therapy. Median response duration was 28.1 months (range, 10.5-80.3+ months). Median TTP was 29.3 months (range, 12.1-81.5+ months). In patients with ongoing response, median TTP was 53.9 months (range, 49-82+ months). Conclusions: ⁹⁰Y ibritumomab tiuxetan produces durable long-term responses in patients with relapsed/refractory B-cell NHL. Failure to respond to prior therapy does not preclude achieving a long-term response with ⁹⁰Y ibritumomab tiuxetan.