Secondary acute myelogenous leukemia with MLL gene rearrangement following radioimmunotherapy (RAIT) for non-Hodgkin's lymphoma

Yttrium 90 ibritumomab tiuxetan in lymphoma

Radioimmunoconjugates are radioisotope-bound monoclonal antibodies that target radiation specifically to sites of lymphoma involvement. Initial studies of 90Y-ibritumomab tiuxetan in non-Hodgkin's lymphoma (NHL) have suggested benefit in patients with relapsed or refractory indolent disease. However, the routine adoption of this agent is tempered by concerns of associated toxicities and unclear long-term benefit. A comprehensive search for studies on 90Y-ibritumomab tiuxetan use in lymphoma was completed. The aims of this systematic review were to summarize and evaluate the evidence on: (1) the benefits and risks of this novel therapy; (2) predictors for response and toxicity; and (3) the role of dosimetry and imaging studies prior to treatment. A total of twenty trials investigating the use of 90Y-ibritumomab tiuxetan for the treatment of adult patients with NHL were identified. In trials of patients with relapsed or refractory indolent NHL, overall response rates ranged from 67 - 83%. In patients with follicular NHL refractory to the monoclonal antibody, rituximab, response rates remained high (74%). However, in rituximab-naïve patients with relapsed or refractory indolent or transformed NHL, the higher response rate seen with 90Y-ibritumomab tiuxetan therapy compared to rituximab monotherapy has not translated into clear improvements in time-to-progression or survival. 90Y-ibritumomab tiuxetan is an active agent in relapsed and refractory non-Hodgkin's lymphoma that should be considered in select patients.

Treatment-Related Myelodysplastic Syndrome and Acute Myelogenous Leukemia in Patients Treated With Ibritumomab Tiuxetan Radioimmunotherapy

Purpose

To investigate the incidence of treatment-related myelodysplastic syndrome (t-MDS) and treatment-related acute myelogenous leukemia (t-AML) after treatment with ibritumomab tiuxetan radioimmunotherapy.

Patients and Methods

Analysis of the incidence of t-MDS and t-AML in 746 patients with non-Hodgkin's lymphoma (NHL) treated with the ibritumomab tiuxetan regimen in registration and compassionate-use trials between 1996 and 2002.

Results

Nineteen patients (2.5%) developed t-MDS or t-AML at a median follow-up of 4.4 years (range, 0 to 9.3). These malignancies were diagnosed at a median of 5.6 years (range, 1.4 to 13.9) after the diagnosis of NHL and 1.9 years (range, 0.4 to 6.3) after radioimmunotherapy. The annualized rates were 0.3% per year after the diagnosis of NHL and 0.7% per year after treatment. Most patients with t-MDS or t-AML had multiple cytogenetic aberrations, commonly on chromosomes 5 and 7, suggesting an association with previous exposure to chemotherapy.

Conclusion

Analysis of data from patients in registration and compassionate-use trials suggests that the annualized incidences of t-MDS and t-AML are consistent with that expected in patients with NHL who have had extensive previous chemotherapy treatment and do not appear to be increased after treatment with the ibritumomab tiuxetan regimen. Cytogenetic testing before treatment with radioimmunotherapy may identify existing chromosomal abnormalities in previously treated patients, particularly those who have been treated with alkylating agents and purine nucleoside analogs and would be at higher risk for t-MDS or t-AML.

Therapy-related myelodysplastic syndrome and acute myeloid leukemia following initial treatment with chemotherapy plus radioimmunotherapy for indolent non-Hodgkin lymphoma

Patients with indolent non-Hodgkin lymphoma (I-NHL) often receive multiple courses of cytotoxic chemotherapy over several years. Radioimmunotherapy (RIT) has become an important part of treatment for relapsed patients and tositumomab/lodine I-131 tositumomab is a promising regimen currently being incorporated into first-line therapy. While treatment-related myelodysplasia (tMDS) and acute myeloid leukemia (tAML) are well-known, poor-prognosis complications of conventional chemotherapy and radiation therapy, they have not been previously observed as a consequence of initial treatment with RIT-based regimens. We describe four patients with tMDS/tAML who received a sequential chemotherapy and tositumomab/lodine I-131 tositumomab program as their initial and only lymphoma treatment. Our findings suggest that the potential risk of these important complications must be considered in the development of this novel therapeutic strategy in the first-line setting.

Treatment-related myelodysplastic syndrome/acute myeloid leukemia in survivors of childhood cancer--an update

Treatment-related myelodysplastic syndrome/acute myeloid leukemia (t-MDS/t-AML) is a devastating complication of treatment for childhood cancer. However, the major cause of premature death of children treated for cancer remains their primary cancer. The understanding of the presentation, incidence, predisposing risk factors and pathobiology of t-MDS/t-AML is increasing. This increased understanding has not yet been translated into improved outcomes of therapy for t-MDS/t-AML. However, newer approaches are under study.

Use of 90Y-ibritumomab tiuxetan in non-Hodgkin’s lymphoma

The increase in the incidence of non-Hodgkin's lymphoma (NHL) that has occurred over recent decades is expected to continue. Therapeutic options for patients with NHL have improved over the past 20 years, but almost all patients with low-grade lymphoma and approximately 50% of patients with high-grade lymphoma eventually die of their disease, regardless of the regimen used. Thus, there is a continuing need for novel therapeutic options. One such strategy is targeted radioimmunotherapy, which is an attractive approach because lymphoma cells are inherently sensitive to radiation. 90 Y-ibritumomab tiuxetan (Zevalin; Biogen Idec Inc, San Diego, CA, and Schering AG, Berlin, Germany) was the first radioimmunotherapy agent to be approved by the US Food and Drug Administration for the treatment of patients with relapsed, low-grade B-cell NHL. 90Y-ibritumomab tiuxetan comprises the murine IgG1 anti-CD20 antibody ibritumomab, covalently linked to the beta-emitter 90 Y by a chelator tiuxetan. A prospective trial comparing 90Y-ibritumomab tiuxetan with single-agent rituximab showed an overall response rate (ORR) to 90Y-ibritumomab tiuxetan of 80% (34% complete response [CR]/unconfirmed CR [CRu]) compared with 56% (20% CR/CRu) with rituximab (P = .002). Of patients achieving a CR/CRu, 32% were still in remission at 3 to 4 years of follow-up. Similar efficacy (83% ORR, 43% CR/CRu) has been reported with 90 Y-ibritumomab tiuxetan in patients with relapsed or refractory low-grade NHL with mild thrombocytopenia (platelet counts 100,000 to 149,000/mm3 ), and in patients with rituximab-refractory NHL (ORR 74% [CR 15%] compared with an ORR 32% to last rituximab treatment). Safety data compiled from patients entered into five studies have confirmed initial observations that the toxicities encountered with 90Y-ibritumomab tiuxetan therapy are mainly hematologic and transient. As part of a consolidated clinical approach to the ongoing development of 90Y-ibritumomab tiuxetan, studies are currently being conducted in the United States and Europe to examine the role of this agent in first-line therapy of indolent NHL, in diffuse large B-cell lymphoma, and in combination with chemotherapy with peripheral blood stem cell support.