Yttrium-90 ibritumomab tiuxetan consolidation versus rituximab maintenance therapy after induction chemotherapy in patients with indolent non-Hodgkin lymphoma: a single-institution experience

ABSTRACT OBJECTIVES Indolent B-cell non-Hodgkin lymphomas (iNHLs) are considered incurable. Rituximab maintenance and yttrium-90 ibritumomab tiuxetan (90Y-IT) consolidation are promising post-remission therapies. However, only one randomized phase II trial has compared their efficacies and adverse effects. Here, we compared the efficacy and safety of 90Y-IT consolidation and rituximab maintenance in iNHL patients. METHODS We retrospectively examined 75 iNHL patients with complete or partial response after initial chemotherapy between January 2008 and December 2018. Twenty-seven patients received 90Y-IT consolidation and 48 received rituximab maintenance (every 2 months for 2 years). Progression-free survival (PFS), overall survival (OS), and time to next treatment (TTNT) were estimated from the start of the treatment, and adverse effects were evaluated. RESULTS After a median 3.6-year follow-up, the 5-year PFSs of the 90Y-IT consolidation and rituximab maintenance groups were 75.5% and 82.4%, respectively (log-rank test, p？=？0.839), and the 5-year OSs were 100% and 97.8%, respectively (log-rank test, p？=？0.465). The corresponding median TTNTs were not reached (log-rank test, p？=？0.804). The commonest adverse effect with 90Y-IT consolidation was hematotoxicity; lower rates and grades of cytopenia were observed in patients who received rituximab maintenance. Secondary malignancies were observed in 1 patient (4%) who received 90Y-IT consolidation and 2 patients (4.2%) who received rituximab maintenance (Fisher’s exact test, p？>？0.99). CONCLUSION 90Y-IT consolidation and rituximab maintenance were similar with respect to PFS, OS, and TTNT. However, the features and grades of adverse effects significantly differed. Patient-specific characteristics should be considered when deciding post-remission treatments