Rituximab maintenance added to ibrutinib-containing therapy in younger, untreated MCL patients: secondary analysis of TRIANGLE

The multinational phase 3 TRIANGLE trial established an ibrutinib-containing therapy without autologous stem-cell transplantation (ASCT) as the new standard for younger, treatment-naïve patients with mantle cell lymphoma (MCL). Secondary analysis of TRIANGLE, investigating the benefit of rituximab maintenance (RM) within this new standard, has now been published. This analysis included patients randomized to ibrutinib-containing therapy without (I) or with (A + I) ASCT who responded to induction/ASCT. RM was given per national and center practice. Progression-free survival (PFS; primary endpoint) and overall survival (OS) were compared with IPTW Kaplan-Meier curves and log-rank tests. Among responders after induction/ASCT (I: 274; I + ASCT: 237), RM was given to 61% (I) and 64% (A + I). The figure shows that RM prolonged PFS in ibrutinib-containing treatment arms (I: 4-year PFS probability RM versus no RM 85% versus 73%; p=0.003 and A + I 90% versus 75%; p<0.001), with trends toward prolonged OS in RM groups. RM groups were at higher risk of grade 3 to 5 infectious toxicity (I: 34% versus 11%; A + I: 41% versus 18%). The authors conclude that these findings support adding RM to BTK inhibitor treatments in younger, untreated MCL patients.