Phase III Trial of Consolidation Therapy With Yttrium-90–Ibritumomab Tiuxetan Compared With No Additional Therapy After First Remission in Advanced Follicular Lymphoma

PurposeWe conducted an international, randomized, phase III trial to evaluate the efficacy and safety of consolidation with yttrium-90 (90Y)–ibritumomab tiuxetan in patients with advanced-stage follicular lymphoma in first remission.Patients and MethodsPatients with CD20+stage III or IV follicular lymphoma, who achieved a complete response (CR)/unconfirmed CR (CRu) or partial response (PR) after first-line induction treatment, were randomly assigned to receive90Y-ibritumomab tiuxetan (rituximab 250 mg/m2on day −7 and day 0 followed on day 0 by90Y-ibritumomab tiuxetan 14.8 MBq/kg; maximum of 1,184 MBq) or no further treatment (control). The primary end point was progression-free survival (PFS), which was calculated from the time of random assignment.ResultsA total of 414 patients (consolidation, n = 208; control, n = 206) were enrolled at 77 centers.90Y-ibritumomab tiuxetan consolidation significantly prolonged median PFS (after a median observation time of 3.5 years) in all patients (36.5 v 13.3 months in control arm; hazard ratio [HR] = 0.465; P < .0001) and regardless of whether patients achieved PR (29.3 v 6.2 months in control arm; HR = 0.304; P < .0001) or CR/CRu (53.9 v 29.5 months in control arm; HR = 0.613; P = .0154) after induction treatment. Median PFS with consolidation was prolonged in all Follicular Lymphoma International Prognostic Index risk subgroups. After90Y-ibritumomab tiuxetan consolidation, 77% of patients in PR after induction converted to CR/CRu, resulting in a final CR rate of 87%. The most common toxicity with90Y-ibritumomab tiuxetan was hematologic, and grade 3 or 4 infections occurred in 8% of patients.ConclusionConsolidation of first remission with90Y-ibritumomab tiuxetan in advanced-stage follicular lymphoma is highly effective with no unexpected toxicities, prolonging PFS by 2 years and resulting in high PR-to-CR conversion rates regardless of type of first-line induction treatment.