Registry of RadioImmunoTherapy: Analysis of Outcomes of Recurrent or Refractory Non-Hodgkin Lymphoma Patients Treated with 90Y Ibritumomab Tiuxetan.

Background: 90Y Ibritumomab tiuxetan (90Y-RIT) is approved for the treatment of refractory or recurrent non- Hodgkin follicular lymphoma (NH FL). The aim of this study was to collect data of NH FL patients (p) treated with RIT within the clinical practice setting, to retrospectively analyze treatment effectiveness and tolerability, in order to provide a pragmatic approach to experimental data.

Methods: P treated, since commercial availability in Spain and Portugal, with 90Y - RIT, were registered. Effectiveness endpoints retrospectively studied were: objective response rate (ORR), time to progression (TTP) overall survival (OS) and safety. Clinical prognostic factors were collected to asses their possible influence upon treatment effectiveness, by multivariate analyses.

Results: 118 p from 44 centres have been registered, treated since commercial availability until March 2007: M/F, 55.9%/44.1%; mean age, 58.6 years (22–83); ECOG 0–1, 83.5%. Eighty five p had FL (72%) and 33 non-FL (28%). Median time since NHL diagnosis was 3.9 years (0.4–23.9). Before 90Y-RIT, most of the cases were refractory to previous treatments (73.5%). FLIPI distribution previous to RIT was: low-risk 50.6%, intermediate-risk 22.4% and high-risk 25.9%. IPI distribution previous to RIT was: low-risk 33.3%, intermediate low-risk 30.3%, intermediate high-risk 18.2% and high-risk 15.2%. Median number of previous treatments was 3 (range 1.0–8.0). ORR was 67.8% (95% CI: 59.4, 76.2). According to FLIPI ORR was: LR: 90.7%; IR: 63.1%; HR: 59.1%. According to IPI ORR was: LR: 54.5%; ILR: 40.0%; IHR: 33.3%; HR: 40.0%. With a median follow-up time of 7 months, median TTP was 9.9 months (95% CI: 6.4, 13.4) and median OS was 20.9 months (95% CI: 14.1–27.7), with an estimated OS at 1 and 2 years of 73.3% and 44.3%, respectively. High FLIPI score was significantly associated with worse response rate: Odds ratio 0.185 (95% CI: 0.047, 0.732). More than 2 previous treatments was also related with worse response rate, for both FL p and non FL p: Odds ratio 4.025 (95% CI: 1.127, 14.373) and 7.0 (95% CI: 1.173–41.759), respectively. Safety analysis was performed for the global sample, for p with or without previous transplant and for p previously treated or not with Fludarabine containing regimens.

Conclusions: Despite the limitations of the retrospective design of the Registry, these results obtained with 90Y - RIT for lymphoma patients treated within the clinical practice setting are similar to that obtained in clinical trials. Updated data will be presented at the meeting.