Short duration immunochemotherapy followed by radioimmunotherapy consolidation is effective and well tolerated in relapsed follicular lymphoma: 5-year results from a UK National Cancer Research Institute Lymphoma Group study

Summary We report a phase II study to evaluate the efficacy and toxicity of abbreviated immunochemotherapy followed by 90Y Ibritumomab tiuxetan (90Y-IT) in patients with recurrent follicular lymphoma. Of the 52 patients enrolled, 50 were treated with three cycles of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisolone) or R-CVP (rituximab, cyclophosphamide, vincristine, prednisolone), followed by 90Y-IT regimen (15 MBq/kg, maximum 1200 MBq) preceded by two infusions of 250 mg/m2 rituximab. The overall response rate was 98% with complete response (CR) 30% and partial response (PR) 68%. 18 patients with a PR following chemotherapy improved to a CR following 90Y-IT: a conversion rate of 40%. Seven patients with PR following 90Y-IT subsequently improved to a CR 12–18 months later, leading to an overall CR rate of 44%. With a median follow-up of 5 years, median progression-free survival was 23·1 months and overall survival was 77·5% at 5 years. High trough serum rituximab levels (median 112 μg/ml; range 52–241) were attained after four doses of rituximab, prior to 90Y-IT; this was not found to influence response rates. The treatment was well tolerated with few (13·5%) grade 3 or 4 infective episodes and manageable haematological toxicity. Abbreviated immunochemotherapy followed by 90Y-IT is an effective and well-tolerated treatment in recurrent follicular lymphoma patients previously exposed to rituximab. Trial registration: clinicaltrials.gov identifier: NCT00637832.