Efficacy and Safety of Yttrium-90 Ibritumomab Tiuxetan in Older Patients with Indolent Non-Hodgkin Lymphoma.

Radioimmunotherapy (RIT) has emerged as an important treatment options for patients with non-Hodgkin lymphoma (NHL). Yttrium-90 ibritumomab tiuxetan (Zevalin®) consist of ibritumomab, a murine monoclonal antibody to CD20, conjugated to the metal chelator tiuxetan for retention of the beta emitter Yttrium-90. Clinical trials with this agent have demonstrated significant activity in indolent NHL with mild toxicity. The median age of NHL patients included in these trials is mainly < 65 years. Our aim was to evaluate the effectiveness of Zevalin as treatment option for patient > 65 years old with indolent NHL.

Between November 2005 to June 2009 fifteen patients, five males and ten females, median age 76 years (range 67-82), with indolent NHL (13 follicular and 2 small lymphocytic) were treated with Zevalin. Six patients had stage IV disease, five stage III and four stage II. All patients received an initial infusion of rituximab at a dose of 250 mg/m(e)2 on day 1 and a second infusion at same dose on day 8 followed by a weight-based dose of Zevalin (median dose 1006 MBq; range 668-1260). Eight patients perfomed Zevalin as consolidation after first line therapy with Rituximab plus chemotherapy (6 R-CHOP, 1 R-FN, 1 R-COMP): of these three were in complete remission (CR) and five in partial remission (PR). Seven patients perfomed Zevalin in relapse (four in first and three in second relapse).

After RIT 13 of 15 patients were evaluable. Overall response rate was 92% (10 CR, 2 PR); in particular all patients in first line of treatment achieved CR. One patient had stable disease. At a median follow-up of 15 months (range 2-34), all patients are alive in persistent CR or PR. One of two patients in PR achieved CR after successive therapy. Treatment was well tolerated; transient thrombocytopenia (grade 3-4) was seen in 9 patients and transient neutropenia (grade 3-4 ) in 6 patients. Only one patient developed herpex-zoster virus infection.

In our experience, Zevalin produces high response rate (up to 90%) and durable remission without severe toxicity in older patients with indolent NHL. Notably, in first-line treatment, RIT resulted in PR-to-CR conversion in all five patients in PR after the R-chemotherapy. The favourable safety profile of this regimen makes it an effective consolidation treatment for older patients who, because of age and comorbidity, are not eligible for intensive treatment as high-dose therapy and stem cell transplantation.

No relevant conflicts of interest to declare.