Impact of Rituximab Maintenance on outcomes in Follicular Lymphoma: An indian experience

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 outcomes in FL patients.

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 were overall survival (OS) and progression-free survival. Secondary outcomes were factors affecting OS & PFS.

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. Based on the Follicular Lymphoma International Prognostic Index (FLIPI-1), 27 (28 %) were low risk, 9 (10 %) intermediate risk, and 59 (62 %) were high risk. The complete remission (CR) was achieved in 71 % of patients. During follow-up, 27 (28 %) patients experienced relapsed and 8 patients transformed to diffuse large B-cell lymphoma (DLBCL). At a median follow-up of 63 months, the median OS was not reached. The median PFS was 122 months in the RM group and 94 months in the non-RM group, with 5-year PFS of 91.6 % vs 59.3 %, respectively (log-rank p = 0.017). Rituximab maintenance was independently associated with improved PFS (adjusted HR 0.28, 95 % CI: 0.12-0.65, p = 0.003). Failure to attain CR (aHR 2.49, 95 % CI: 1.20-5.19, p = 0.015) and bone marrow involvement (aHR 2.92, 95 % CI: 0.99-8.63, p = 0.05) were independently associated with inferior PFS.

Rituximab maintenance after induction immunochemotherapy significantly improved PFS. This is the first study from India demonstrating the impact of rituximab maintenance in FL.