Subsequent chemotherapy regimens are well tolerated after radioimmunotherapy with Yttrium-90 ibritumomab tiuxetan for non-Hodgkin's lymphoma

Purpose: Yttrium-90 (⁹⁰Y) ibritumomab tiuxetan (Zevalin; IDEC Pharmaceutical, San Diego, CA) is an effective therapy for patients with relapsed B-cell non-Hodgkin's lymphoma. The predominant toxicity of ⁹⁰Y ibritumomab tiuxetan has been myelosuppression, and concern has been expressed about the tolerability of further treatment after this therapy. The goal of this analysis was to evaluate the therapy given to patients who relapsed after ⁹⁰Y ibritumomab tiuxetan. Patients and Methods: A retrospective analysis was performed on 58 patients treated at a single institution on five separate protocols that used ⁹⁰Y ibritumomab tiuxetan 0.4 mCi/kg. All patients had experienced disease progression after ⁹⁰Y ibritumomab tiuxetan treatment and received subsequent therapy. The toxicity seen in this cohort of patients with subsequent treatment regimens was analyzed and compared with that of control groups who did not receive ⁹⁰Y ibritumomab tiuxetan. Results: The median number of subsequent therapies was two (range, one to seven). Sixteen (28%) of the 58 patients received growth factor support with subsequent chemotherapy, and two patients were treated with reduced doses because of persistent pancytopenia. Eight patients subsequently had an autologous stem-cell transplantation with stem cells collected after ⁹⁰Y ibritumomab tiuxetan therapy. Excluding patients hospitalized at the time of transplantation, 13 patients were hospitalized for neutropenic fever, thrombocytopenia, or both. When compared to patients who did not receive ⁹⁰Y ibritumomab tiuxetan, there was no significant difference in toxicity. Conclusion: We conclude that chemotherapy or autologous stem-cell transplantation after prior therapy with ⁹⁰Y ibritumomab tiuxetan is feasible and reasonably well tolerated. The toxicity with subsequent therapy seems similar to that in patients not treated with ⁹⁰Y ibritumomab tiuxetan.