P048 | MAINTENANCE WITH RITUXIMAB IN POST-INDUCTION MARGINAL ZONE LYMPHOMA: YES OR NO? OUR EXPERIENCE WITH LONG FOLLOW-UP.

Marginal zone lymphoma (MZL) is a B cell non-Hodgkin's lymphoma (NHL) that accounts for approximately 5%–17% of all NHL in adults The three major subtypes of MZL defined by the World Health Organization (WHO)—are splenic MZL, mucosa-associated lymphoid tissue (MALT) MZL, and nodal MZ. numerous studies have demonstrated the efficacy and tolerability of rituximab in combination with chemotherapy regimens, with an overall improved response rate of up to 90%–100%. Despite the improved response and progression or event-free survival rates achieved with first-line rituximab-containing regimens, relapses still persist once the treatment is completed. Here we report the results and long follow-up of our study evaluating the effect of rituximab-maintenance or not treatment following R-based therapy as a first-line therapy on the progression free and overall survival of MZL patients. from 2011 to 2023 we treated 60 patients with marginal NHL (27 F; 33 M) with a median age of 66 years (range 42-86 years); 34 splenic; 13 nodal and 13 MALT. Patients treated in induction with R-Benda: 34(56%); R-alone: ​​18(30%); R-FluCy: 4(7%); R-CVP: 3(5%); R-CHOP: 1(2%). ORR was documented in 58/60(97%). 36/58(62%) accepted maintenance therapy with rituximab and 22/50(38%) did not. With a median observation of 65 months (range 7-164 months) the PFS is 88% vs 50% (p:0.002) and the OS is 82% vs 44% (p:0.007) respectively in the M and no M groups with a statistically significant difference. 15/58(26%) died; 5/36(14%) in group M, 3 for viral infections (2 COVID and 1 encephalitis) and 2 for other causes; in the no M group 10/22(45%): 3 from lymphoma; 3 for viral infections (2 COVID and 1 CMV) and 4 for other causes. In conclusion from our experience, maintenance with rituximab improves the results in patients with marginal lymphoma with a relatively low impact on complications related to infectious problems. The new drugs active in the treatment of marginal lymphomas (BTK inhibitors) in association with anti-CD20 could the future for evaluating a chemotherapy-free term therapy (after 2 years) in the first line, impacting both the quality of life and the results or adverse events in this cohort of patients.