The Response Study of Yt90-Zevalin in Patients With Diffuse Large B-cell Lymphoma After 6 Cycles of CHOP

Diffuse large B-cell lymphomas (DLBCL) are the most common lymphoid neoplasm and account for 30% to 40% of adult non-Hodgkin lymphomas (NHL). DLCBL is a potentially curable disease. The ultimate goals of introducing new modality treatments such as monoclonal antibody (Ab)-targeted therapy are to increase complete remission (CR) rate and prolong event-free survival and overall survival.In phase II trials, it was shown that in DLBL the addition of rituximab to CHOP was feasible, with an increase in ORR, including CR and an increase in the OS and PFS in patients with DLBL.2 The benefit of R-CHOP was consistent across all subgroups of patients tested, including good and poor risks according to IPI and independent of younger than 70 years and older than 70 years of age. Recently, new radiolabeled monoclonal antibodies have been established in the therapy of malignant lymphoma which can induce high remission rates. Radiolabeled antibodies are particularly effective as lymphoma cells are highly sensitive to radiation. In addition, the local emission of radiolabeled antibodies is able to destroy cells in close proximity to the bound antibody (bystander effect) therefore circumventing the problem of limited perfusion of bulky or poorly vascularized tumors.Ibritumomab is covalently linked to the tiuxetan chelate and radiolabeled with Yt90, producing Yt90-ibritumomab tiuxetan (Yt90-Zevalin). To optimize biodistribution, Rituximab is given prior to the radiolabeled antibody. Yt90-ibritumomab-tiuxetan-treatment was compared to a standard course of Rituximab. ORR in the Yt90-ibritumomab tiuxetan group was significantly higher than ORR in the Rituximab group (80% vs. 56% according to International Workshop Response criteria or 73% vs. 47% according to protocol-defined evaluation of response). Since radioimmunotherapy represents a significant advance over unlabeled immunotherapy for the treatment of patients with B-cell non-Hodgkin's lymphoma, it is worthwhile to study the consolidation therapy with Yt90-ibritumomab tiuxetan (Yt90-Zevalin) in patients who achieved at least unconfirmed partial remission after 6 cycles of CHOP therapy.