A Single Center Phase II Trial Of ⁹⁰yttrium-Ibritumomab-Tiuxetan Produces High Response Rates As First-Line Therapy For Early Stage B Cell Indolent Lymphoma, Including Bulky Disease

⁹⁰YIT is approved for the treatment of relapsed follicular lymphoma or as consolidation therapy after first line chemotherapy. Its role as therapy for the front line treatment of early stage B cell indolent lymphoma is under investigation.

Thirty-one patients with B cell lymphoma: grade 1 or 2 follicular lymphoma [FL], or marginal zone lymphoma (MZL) with stages I or II were enrolled for treatment with Zevalin (⁹⁰yttrium-ibritumomab-tiuxetan [⁹⁰YIT]). Patients received ⁹⁰YIT according to standard procedure. Primary end points were overall response rates and progression-free survival. Initial evaluation included CT scans, PET-CT, CBC and bone marrow biopsies. Assessment of response was made at 4 months, and monitored every 3, 6 and 12 months during year 1, 2 and 3 of follow up, respectively. CBC was analyzed every 2 weeks until recovery of counts. Median and range for quantitative, absolute and relative frequencies for categorical variables were calculated. PFS was estimated by using Kaplan-Meier method.

Twenty-one patients had FL and 10 had MZL. The median age was 57 years (range 28-87) with 6/31 (19%) having bulky lymphoma (greater than 5 cm diameter). The overall response rate was 100% with CR 87% and Cru 13% with a median follow up of 56 months for the censored observations. The median progression free survival time has not been reached. 10 patients relapsed; 8/20 (40%) with FL and 2/11 (18%) with MZL. The rate of relapses was 33% in bulky and 32% in nonbulky lymphoma. Adverse events were primarily hematologic; the incidence of grade 3 and 4 neutropenia, thrombocytopenia, and anemia were 45% and 16%, 19% and 16% and 0% and 3%, respectively. Non-hematologic toxicity never exceeded grade 2 according to CTCAE v3.0.

⁹⁰YIT is well-tolerated and has achieved high response rates in patients with early stage B cell indolent lymphoma. Bulky disease did not adversely affect tumor responses.

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