90Y-Ibritumomab-Tiuxetan Consolidation in First-Line Complete Response Follicular Lymphoma Patients. Single Center Outcomes Analysis after Five Years Median Follow-up

Abstract

Introduction: Follicular lymphoma (FL) is the second most common non-Hodgkin lymphoma accounting for around 22% of them. Their natural history is characterized by multiple relapses and progressively shorter response durations after every new line of therapy for this is desirable to offer the best first-line approach to each patient. However, still now this aspect remains unclear. In the current guidelines several first line options are included: immunotherapy (Rituximab (R) x4 or Lenalidomide+/- R), immunochemotherapy (CHOP, RCVP, Bendamustine + R), radioimmunotherapy for elderly patients. Moving forward, the consolidation with radioimmunotherapy or extended dose immunotherapy (R every 8 weeks for 4 or 12 doses) still appears as an optional part of the therapy (NCCN V3.2016). Radioimmunotherapy with 90Yttrium-ibritumomab tiuxetan (90Y-IT) is available in our institution since 2006 and more than 100 patients have been treated with RIT since then. Here an institutional analysis focus in their use as consolidation is presented.Aim: To analyze the experience with 90Y-IT as a consolidation therapy in patients in CR after first-line therapy.Patients & methods: A retrospective analysis was performed including all the patients that have received RIT with 90Y-IT. Inclusion criteria were: patients 18 years or older with a grade 1-2a follicular lymphoma, RIT was received as a consolidation therapy in complete response (CR) after a first-line therapy. Demographic and follow-up data were included. International working group (IWG) criteria of response was used. Progression free survival (PFS) was calculated from the date of RIT to the date of a confirmed relapse according IWG criteria, overall survival (OS) was calculated from the FL diagnosis to the last contact.Results: A total of 31 FL patients have received 90Y-IT been in CR after a first-line of therapy and were included for the study. Mean age at diagnosis was 61.2 (29-86) years with a female predominance (19, 61.3% vs. 12, 38.7%). 80.6% (26) with ECOG 0-1 and 19.4 ECOG 2. A third of them (10, 32.3%) were diagnosed with low tumor burden (stage I-II), 2 (9.7) of them presented extra nodal infiltration (subcutaneous and gut) and 12 (38.7%) showed bone marrow infiltration demonstrated by flow cytometer or biopsy. There were no patients with bulky disease. Stages: I: 7 (22.6%), II: 3 (9.7%), III: 9 (29.1%), IV: 12 (38.7%). As first-line therapy the patients received: Rx4: 11 (35.5%) cases, R-Cyclophosphamide vincristine prednisone (R-COPx6): 3 (9.7%) cases and 17 (54.8) R-cyclophosphamide doxorubicin, vincristine and prednisone (R-CHOP21x4-6). The median follow-up was 58.0 (10-107) months. During this time only 5 (16.1%) of patients have relapsed and need another therapy. None of the patients that have received R-CHOP+90Y-IT have relapsed; the relapsed patients received Rx4 (4) and R-COP (1). The median PFS after 90Y-IT has not reached, the mean was 83.3 (71.7-94.98) months, see Fig 1. Four (12.9%) patients have died, none of them were relapsed and the mortality was due to other causes. The median OS was not reached, the mean was 95.8 (85.6-106.1) months. As long-term events one 82 years old patient developed a colon cancer after 67 months of RIT, one 72 years old female a breast cancer after 17 months of RIT and one 71 years patients a MGUS after 24 months of RIT, none of them related with mortality events.Conclusions: The use of immunotherapy with rituximab or combined schedules with immunochemotherapy (R-COP and R-CHOP) followed by consolidation with 90Y-IT remains as a valid option for follicular lymphoma patients. After ~5 years of follow-up: 63.6% (Rx4+RIT), 66.7% (R-COP+RIT) and 100% (R-CHOP+RIT) of patients continue with complete response and off of therapy. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.