A Phase II Trial of CHOP Chemotherapy Followed by Yttrium 90 (⁹⁰Y) Ibritumomab Tiuxetan (Zevalin®) for Previously Untreated Elderly Diffuse Large B-Cell Lymphoma (DLBCL) Patients.

In the last 20 years, the major improvement over the use of CHOP has been the addition of anti-CD20 immunotherapy (Rituximab). This advancement was first demonstrated in a randomized trial in elderly patients with diffuse large B-cell lymphoma (DLBCL). Single-agent radioimmunotherapy activity, in particular Yttrium 90 (⁹⁰Y) Ibritumomab Tiuxetan (Zevalin®), has been demonstrated in heavily pretreated DLBCL patients. Recently, the preliminary data of a phase II trial have showed that ⁹⁰Y Ibritumomab Tiuxetan have useful activity in the treatment of relapsed/refractory elderly DLBCL (Morschhauser et al, Blood 2004, 104: 41a), with no unexpected toxicities observed. The results of this study support a further evaluation of ⁹⁰Y Ibritumomab Tiuxetan in combination with chemotherapy earlier in the time course of elderly DLBCL. We conducted a prospective, single-arm, open-label, non-randomized, phase II to evaluate the efficacy and safety of ⁹⁰Y Ibritumomab Tiuxetan of a novel new approach combining induction chemotherapy with CHOP followed by consolidation with ⁹⁰Y Ibritumomab Tiuxetan for patients with previously untreated elderly DLBCL. Patient eligibility was represented by: patients older than 60 years with biopsy-proven, untreated, bidimensionally measurable stage II, stage III, or stage IV DLBCL expressing the CD20 antigen; WHO performance status of 0 to 2. All patients signed a written informed consent approved in accordance with institutional guidelines. The study was approved by the institutional review board. Patients were treated with standard CHOP chemotherapy every 21 days for 6 cycles. Patients were restaged 4 to 6 weeks after completion of the sixth cycle of CHOP chemotherapy. Patients achieving at least a partial response after 6 cycles of CHOP chemotherapy were eligible for consolidation with ⁹⁰Y Ibritumomab Tiuxetan provided the granulocyte count was greater than 1500/μL, the platelet count exceeded 100.000/μL, and the bone marrow examination at the completion of CHOP chemotherapy demonstrated no more than 25% involvement with lymphoma. All patients were to receive a single dose of ⁹⁰Y Ibritumomab Tiuxetan 14.8 MBq/kg (0.4 mCi/kg) up to a maximum dose of 1184 MBq (32 mCi). A total of 20 patients have been enrolled: 12 were male and 8 female; the median age was 68 years (range 61–84); 6 were stage II, 14 stage III-IV. After the CHOP treatment the overall response rate was 100%, including 15 (75%) CR and 5 (25%) PR. Treatment was well tolerated; grade ≥ 3 AEs were seen in 13 patients; the most common grade ≥ 3 AEs was neutropenia. After the treatment of all 20 patients with ⁹⁰Y Ibritumomab Tiuxetan, 4/5 (80%) patients improved their remission status from PR to CR. The ⁹⁰Y Ibritumomab Tiuxetan toxicity included grade ≥ 3 hematologic AEs in 11/20 patients; the most common grade ≥ 3 AEs were neutropenia (11 patients) and thrombocytopenia (7 patients). Transfusions of red cells and/or platelets were given to 2 patients. Time to event analyses, including TTP and duration of response are pending further follow-up. These preliminary data indicate the feasibility, tolerability, and efficacy of the CHOP plus ⁹⁰Y Ibritumomab Tiuxetan regimen for patients with untreated elderly DLBCL.