Prolonged progression-free survival and preserved quality of life in the Canadian prospective study of tositumomab and iodine(131)-tositumomab for previously treated, rituximab-exposed, indolent non-Hodgkin lymphoma.

Radioimmunotherapy offers a unique treatment modality for indolent non-Hodgkin lymphoma (iNHL). We report 5-year outcomes and quality of life (QoL) in tositumomab and iodine(131)-tositumomab (TST/I(131)-TST) treated patients with iNHL previously treated with rituximab. Ninety-three patients with ≥ 2 lines of therapy, responding to last treatment, were enrolled at 12 Canadian centers. Median age, disease duration and number of prior therapies (#PTx) were 59 years, 4.9 years and 5, respectively. Outcomes were response rate (43.0%), median progression-free survival (mPFS) (12.0 months), 5-year PFS (27%) and median overall survival (OS) (59.8 months). In responders, median response duration and mPFS were not reached. Improvements in QoL were seen by week 7. In univariate and multivariate analyses, hemoglobin, disease bulk and body surface area (BSA) predicted OS, whereas lactate dehydrogenase (LDH), bulk, BSA and #PTx predicted PFS. Most common adverse events (AEs) were fatigue and nausea. Two cases of myelodysplastic syndrome (MDS) were reported. TST/I(131)-TST was associated with durable responses, and prolonged OS and PFS in heavily pretreated iNHL.