P3-094Yttrium-90 ibritumomab tiuxetan consolidation versus rituximab maintenance therapy for indolent non-Hodgkin lymphoma

Abstract Background Indolent non-Hodgkin lymphoma is a common B-cell lymphoma that is considered incurable. Post-remission therapies seek to prolong survival. Rituximab (R) maintenance and yttrium-90 ibritumomab tiuxetan (90Y-IT) consolidation are promising post-remission therapies. However, until now, no trials have compared their efficacy and adverse effects. Method To this effect, we retrospectively examined 75 patients with consecutive indolent lymphoma with complete response or partial response after initial chemotherapy between January 2008 and December 2018. Patients received either 90Y-IT consolidation (27 patients) or R maintenance therapy (2 years, every 2 months, 48 patients). Progression-free survival (PFS), overall survival (OS), and time to next treatment (TTNT) from the start of post-remission therapies were estimated using the Kaplan-Meier Method, and adverse effects were evaluated. Result After a median follow-up of 3.6 years (range, 0.5-13.1 years), 5-year PFS of 90Y-IT consolidation and R maintenance therapy were 75.5% and 82.4%, respectively (log-rank test, p = 0.839). OS of 90Y-IT consolidation and R maintenance therapy were 100% and 97.8%, respectively (log-rank test, p = 0.465). Median TTNT of 90Y-IT consolidation and R maintenance therapy were not achieved (log-rank test, p = 0.804). The most common adverse event with 90Y-IT consolidation was hematotoxicity, whereas lower rates and grades of cytopenia were observed in patients who received R maintenance therapy. Secondary malignancies were observed in 1 patient (4%) who received 90Y-IT consolidation and in 2 patients (4.2%) who received R maintenance therapy (Fisher’s exact test, p = 1.00). Conclusion 90Y-IT consolidation and R maintenance therapy were similar with respect to PFS, OS, and TTNT. However, the features and grades of adverse effects were significantly different. Patient-specific characteristics should be considered while choosing between these post-remission therapies.