Selecting patients for treatment with 90Y ibritumomab tiuxetan (Zevalin).

Yttrium 90 ibritumomab tiuxetan (Zevalin; Biogen Idec Inc, Cambridge, MA) was the first radioimmunotherapeutic agent approved by the US Food and Drug Administration. It is indicated for treating patients with relapsed or refractory low-grade, follicular, or transformed B-cell non-Hodgkin's lymphoma, including patients with rituximab-refractory follicular non-Hodgkin's lymphoma. Proper patient selection is essential for optimizing the efficacy and safety of treatment with (90)Y ibritumomab tiuxetan. It may be advisable to use (90)Y ibritumomab tiuxetan relatively early in a patient's course of treatment because overall and complete response rates, and the estimated median duration of response, are higher among patients who have had fewer median prior antineoplastic regimens than among those who have had a greater median number of such regimens. Furthermore, the myeloablative effect of multiple courses of chemotherapy can preclude the later use of (90)Y ibritumomab tiuxetan. In contrast, other therapies, including chemotherapy and rituximab, can be used safely and successfully after (90)Y ibritumomab tiuxetan without concerns about increased hematologic toxicity from the previous radioimmunotherapy. The main adverse event associated with (90)Y ibritumomab tiuxetan therapy is hematologic toxicity and, as a result, only patients with adequate bone marrow reserves and less than 25% lymphoma marrow involvement should currently be considered for clinical therapy.