Pb2264: clinical features, treatment patterns, and outcomes among 120 patients with malt lymphoma in latin america: a study from the grupo de estudio latinoamericano de linfoproliferativos (gell)

Topic: 18. Indolent and mantle-cell non-Hodgkin lymphoma - Clinical Background: Mucosa-associated lymphoid tissue (MALT) lymphoma accounts for 7% of all non-Hodgkin lymphomas. Because of its indolent course and association to infectious agents (eg Helicobacter pylori-Hp) strategies such as watch-and-wait and antimicrobial therapy are justified in the frontline setting. In patients (pts) with localized disease, radiation therapy (RT) is widely applied with excellent local control whereas systemic therapy is usually reserved for those with advanced disease. Aims: To describe the clinical features, therapy patterns and outcomes of MALT lymphoma pts managed in Latin America. Methods: We designed a retrospective cohort study of pts from Latin America managed at 7 academic centers from 2001 to 2022. Pts data was manually abstracted from medical records in a standardized form. Overall survival (OS) was defined as the time from diagnosis to death from any cause, while progression-free survival (PFS) was defined as the elapsed time from diagnosis to relapse or disease progression or death from any cause. The Kaplan-Meier and the Log-rank test were employed to estimate and compare survival probabilities. Results: A total of 120 pts were identified, 47 (39%) from Peru, 25 (21%) Argentina, 21 (18%) Guatemala, 11 (9%) Cuba, 7 (6%) Uruguay, 5 (4%) Paraguay, 4 (3%) Colombia. Median age at diagnosis was 63 years (27-93) with slight female predominance (51%). Localized stage (I-II) at diagnosis was presented in 93 (78%) pts. Gastric and ocular adnexal were the most common disease sites (n=63, 52% and n=25, 21%, respectively). Primary cutaneous MALT was found in 8 (7%) pts. Infectious etiology with Hp, Chlamydia psittaci and Borrelia burgdorferi were identified in 65% (41/63), 4% (1/25) and 13% (1/8) of gastric, ocular adnexal and cutaneous MALT lymphoma, respectively. Other MALT cases had Hep C (n=2), IgG4 disease (n=3), Hashimoto thyroiditis (n=13) and Sjogren’s syndrome (n=9). Therapy patterns were heterogeneous. In localized stage, watch-and-wait (n=29, 31%) and single-agent rituximab (n=22, 24%) were the most common frontline approaches whereas R-CHOP (n=17, 63%) was common in advanced disease. Frontline RT alone was given to 14 (15%) pts with localized disease. Median RT dose was 24 Gy (4-40). In the entire cohort, the overall response rate (ORR) to frontline was 95% (CR 76%). With a median follow up of 45 months (37-55) the 4-year and median OS and PFS for the entire cohort was 84% and not reached (NR), and 60% and NR, respectively. Pts with localized MALT had significantly better 4-year OS (93 vs 55%, p<0.01) and PFS (69 vs 29%, p<0.01) than advanced stage (Figure). Second line therapy was used in 35 (39%) pts. ORR to second line were 97% (CR 74%). The 4-year and median OS in relapsed pts were 71% and NR. No patients received novel agents during their treatment course (ie BTK, clinical trial). Summary/Conclusion: To our knowledge, this is one of the largest cohorts of pts with MALT lymphoma in Latin America. We found most pts had localized disease with gastric and ocular adnexal as the most common sites. Common approaches in localized MALT were watch-and-wait and single-agent rituximab whereas R-CHOP in advanced stage. Response rates to frontline therapy were high in both localized and advanced MALT. However, outcomes were significantly superior in pts with localized disease. Few pts with localized MALT had frontline RT due to difficulty accessing such therapy in Latin America. We are currently prospectively evaluating pts with MALT lymphoma to better understand therapy patterns and access to novel agents across Latin American countries.Keywords: Indolent non-Hodgkin’s lymphoma