Obinutuzumab versus Rituximab in transplant-eligible Mantle cell lymphoma patients

• Obinutuzumab can safely be used in combination with chemotherapy and in maintenance after ASCT as frontline therapy in MCL patients.

• Obinutuzumab provides better disease control than Rituximab without additional toxicity in MCL.

Obinutuzumab (O) and Rituximab (R) are two CD antibodies that have never been compared in a prospective randomised trial in mantle cell lymphoma (MCL). Herein, we report the long-term outcome of the LYMA-101 (NCT02896582) trial, in which newly diagnosed MCL patients were treated with chemotherapy plus O before transplantation followed by O maintenance (O group). We then compared these patients to those treated with the same treatment design with Rituximab instead of O (R group) (NCT00921414). A propensity score matching (PSM) was used to compare the two populations (O vs R groups) in terms of MRD at the end of induction (EOI), PFS and OS. In LYMA-101, the estimated five-year PFS and OS since inclusion (n=85) were 83.4% (95%CI: 73.5-89.8%) and 86.9% (95%CI: 77.6-92.5%), respectively. At EOI, patients treated in the O group had more frequent bone marrow MRD negativity than those treated in the R group (83.1% vs 63.4% Chi2 p=0.007). The PSM resulted in 2 sets of 82 patients with comparable characteristics at inclusion. From treatment initiation, the O group had a longer estimated five-year PFS (p=0.029; 82.8% versus 66.6%, HR 1.99, IC95 1.05-3.76) and OS (p=0.039; 86.4% versus 71.4% (HR 2.08, IC95 1.01-4.16) compared to the R group. Causes of death were comparable in the 2 groups, the most common cause being lymphoma. Obinutuzumab prior to transplantation and in maintenance provides better disease control and enhances PFS and OS, as compared to Rituximab in transplant-eligible MCL patients.