Impact of rituximab maintenance on outcomes in follicular lymphoma: An Indian experience.

e19044 Background: Follicular lymphoma (FL) is the second most common subtype of non-Hodgkin lymphoma (NHL) and comprises 9% of total NHL in India. Rituximab maintenance (RM) after induction immunochemotherapy improves PFS. However, currently, no data exists from the Indian continent regarding the impact of Rituximab maintenance (RM) on overall survival (OS) & progression-free survival (PFS). Our study aims to assess if RM improves the overall survival of FL patients. Methods: This retrospective study included 95 patients diagnosed with FL meeting GELF criteria and registered at our institute All India Institute of Medical Sciences Delhi between January 2012 -December 2023. Among these, forty -four (46%) patients received 2 years of RM every 2 months after induction immunochemotherapy. The primary outcome was overall survival (OS). Secondary outcomes were progression-free survival (PFS) and factors affecting OS & PFS. Results: Out of the 95 patients who met GELF criteria, 52 were male and 43 were female, with a median age of 53 years (range: 27–81). Advanced Ann Arbor stage III/IV comprises 82 (86%) patients. Bone marrow involvement and bulky disease were observed in 36 (38%) and 29 (31%) patients, respectively, while extra nodal involvement occurred in 65%. Based on the Follicular Lymphoma International Prognostic Index (FLIPI-1), 13 (14%) were low risk, 23 (24%) intermediate risk, and 59 (62%) were high risk. The overall response rate (ORR) was 89%, and complete remission (CR) was achieved in 71% of patients. During follow-up, 27 (28%) patients experienced relapsed and 10 patients transformed to diffuse large B-cell lymphoma (DLBCL). At a median follow-up of 60 months, the median OS was not reached. The median PFS was 114 months. Estimated 5.0-year PFS were 89.0% vs 61.0% respectively in the maintenance vs non-maintenance group. Rituximab maintenance therapy was significantly associated with better OS & PFS (aHR 0.05 , 95% CI 0.01-0.37, p=0.004) & (aHR 0.28 , 95% CI 0.11-0.68, p=0.005) respectively. Conclusions: Rituximab maintenance after induction immunochemotherapy significantly improved PFS and OS. This is the first study from India demonstrating the impact of rituximab maintenance in FL.