PNNL

Abstract

Purpose: The majority of patients with relapsed or refractory B-cell, non-Hodgkin’s lymphoma (NHL) are over 60 years of age, yet they are often denied potentially curative high-dose therapy and autologous stem cell transplants (ASCT) due to the risk of excessive treatment-related morbidity and mortality. Myeloablative anti-CD20 radioimmunotherapy (RIT) can deliver curative radiation doses to tumor sites while limiting exposure to normal organs and may be particularly suited for older adults requiring high-dose therapy. Methods: Patients over age 60 with relapsed B-NHL received infusions of tositumomab anti-CD20 antibody labeled with 5-10mCi I-131 tracer for dosimetry purposes followed 10 days later by individualized therapeutic infusions of I-131-tositumomab (median 525 mCi, range 328-1154 mCi) to deliver 25-27Gy to the critical normal organ receiving the highest radiation dose. ASCT was performed approximately 2 weeks after therapy. Results: Twenty-four patients with a median age of 64 (range 60-76) who had received a median of four prior regimens (range 2-14) were treated. Thirteen (54%) had chemotherapy-resistant disease. The estimated 3-year overall and progression-free survivals were 59% and 51%, respectively with a median follow-up of 2.9 years (range 1-6 years). All patients experienced expected myeloablation with engraftment of platelets (=20K/µL) and neutrophils (=500/µL) occurring a median of 9 and 15 days, respectively following ASCT. There were no treatment-related deaths, and only two patients experienced grade 4 non-hematologic toxicity. Conclusions: Myeloablative RIT and ASCT is a safe and effective therapeutic option for older adults with relapsed B-NHL.