Background: In this retrospective study, we investigated the efficacy and safety of radioimmunotherapy with (90)Yttrium- ibritumomab tiuxetan ((90)Y-RIT) in 9 patients with recurrent follicular lymphoma (FL) who were treated in a consolidation setting after having achieved complete (CR) or partial remission (PR) with Fludarabine, Cyclophosphamide and Rituximab (FCR).
Methods: The median age was 63 years (range 46-77). All patients were relapsed with histologically confirmed CD20-positive (grade 1 or 2) FL, at relapse they received FCR every 28 days: F (25 mg/m(2)x 3 days), C (1 gr/m(2) day 1) and R (375 mg/m(2) day 4) for 4 cycles. Those who achieved at least a PR with <25 % bone marrow involvement were treated with (90)Y-RIT 11.1 or 14.8 MBq/Kg, at 3 months after completing FCR. Patients underwent a further restaging at 12 weeks after (90)Y-RIT with a total body CT scan, FDG-PET/CT and bilateral bone marrow biopsy.
Results: Nine patients completed the treatment: FCR followed by (90)Y-RIT (6 patients at 14.8 MBq/Kg, 3 patients at 11.1 MBq/Kg). After FCR, 7 patients obtained CR and 2 PR; after (90)Y-RIT 2 patients in PR converted to CR 12 weeks later. With a median follow up of 95 months (range 20-114) since FCR and 88 months (range 13-104) since (90)Y-RIT 3 deaths were not related to lymphoma; all 3 deceased patients obtained CR before (90)Y-RIT and died still in CR. The median overall (OS) and progression free survival (PFS) have not been reached, in this analysis both OS or PFS are 67 % at 7.5 year. The most common grade 3 or 4 adverse events were hematologic.
Conclusions: These results confirm the long term efficacy and safety of 4 cycles of FCR followed by (90)Y-RIT in relapsed grades 1 and 2 FL and suggest that this regimen could be a therapeutic option for this setting of patients, specially at age of 60-75 with no unexpected toxicities.
Keywords: 90Y-ibritumomab tiuxetan; Follicular lymphoma; Radioimmunotherapy.