SP19 | RETROSPECTIVE EVALUATION AND LONG FOLLOW-UP OF MONOCENTRIC EXPERIENCE FOR MAINTENANCE THERAPY WHIT RITUXIMAB PET-ORIENTED AFTER INDUCTION WITH R-CHOP IN AGGRESSIVE B NON HODGKIN LYMPHOMA

Randomized trials of maintenance therapy (MT) in diffuse large B cell lymphoma(DLBCL)are inconclusive regarding its effect on overall survival (OS) and disease control. We aim of our retrospective study to evaluate, with long term follow-up, if maitenance therapy with rituximab in patients whit persistent captation PET(pet oriented) after induction with R-CHOP, improve or not the time-to-free relapse survival and overall survival in our cohort of patients. From 2012 to 2023 we treated 150 patients with aggressive NHL-B.110/150 (73%) patients achieved, after induction immunotherapy whit R-CHOP, a complete remission (CR) or an uncertain complete remission (CRu). With CRu we considered patients who, in the re-evaluation with PET CT after induction, had documented persistent uptake in at least one site affected by the lymphomatous disease with a deauville score between 2 and 4. In 28 pts (25.5%) (20 M; 8F) with a median age of 66 years (range 44-77 years) who had obtained a CRu, started maintenance with rituximab 375 mg/m2 every 2 months for 2 years, while in 82 pts (74.5%) (41M;41F) with a median age of 63 years (range 25-81years) who had achieved a CR (PET with deauville score 1), they were only observed. With a median follow-up of 68 months (range 5-155 months), 3 (11%) in the maintenance arm and 14 17%) in the observation arm were relapsed. The PFS projected to 150 months were 90% vs 82%(p:0.3) and the OS projected to 150 months is 60% vs 70% (P:0.7) respectively in the M or no M group whit no statistically difference. 22/110 patients (20%) died; 7/28(25%) in group M: 1 for lymphoma; 2 for secondary neoplasia; 2 due to infection and 2 due to other causes, while 15/82 (18%) died in the “no M” group: 6 due to lymphoma; 6 for other causes; 2 for infections; 1 for secondary neoplasia. In conclusion, although maintenance with rituximab in aggressive non-Hodgkin's lymphomas (validated by international prospective randomized studies but which do not discriminate on the quality of CR) does not appear to give statistically significant advantages. From our observation we have documented that a subgroup of patients (moderate PET-positivity post induction) can benefit from this treatment, obtaining a PFS and OS similar if not superior to the group in RC after R-CHOP not treated. Even the prospect of new therapies in patients with DLBCL that do require not term treatment must further investigate the topic of maintenance in this cohort of patients and who can benefit from it.