Nordic Mantle Cell Lymphoma (MCL) Project: Preemptive Rituximab Treatment of Molecular Relapse Following Autotransplant Can Reinduce Molecular Remission and Prolonged Disease-Free Survival.

Abstract The 2nd. Nordic Lymphoma Group mantle cell lymphoma (MCL2) protocol has demonstrated the importance of Ara-C and Rituximab in the induction chemotherapy and stem-cell mobilisation before high-dose therapy and autologous stem-cell transplant (1). By July 2005, 128 patients (83% stage IV) had completed protocol treatment consisting of 3 series of R-CHOP and 3 series of R-Ara-C, stem-cell harvest and high-dose therapy with BEAM/BEAC with ASCT. The 5-year failure-free and overall survival is 50% and 83% respectively, significantly higher than the historic control group of the Nordic MCL1 protocol with the same treatment without HD-Ara-C and Rituximab (P<0.0001). Patients with a molecular marker (t(11;14) or clonal IgH rearrangement) identified at the time of diagnosis in bone marrow and blood, undergo regular molecular follow-up posttransplant,. Patients who turn PCR-positive or increase their qPCR signal, without clinical disease, are offered preemptive treatment with Rituximab 375 mg/m2 Wx4. Of 75 patients with molecular markers who had completed treatment, 55 remain PCR-negative and 20 have become/remained PCR-pos. posttransplant. Clinical relapse ocurred significantly more often in the latter group (11 of 20) than in the PCR-neg. patients (4 of 55) (P<0.0001) (Fig.1). Ten of the 20 PCR-positive patient did not receive preemptive rituximab: five due to immediate clinical relapse, 2 due to stable qPCR signals, one due to protocol error and two await treatment. Of 10 patients who did receive preemptive rituximab 8 again became PCR-negative and 2 remain PCR-positive. Six of the 10 Rituximab treated patients remain in clinical and molecular remission 200–600 days after the Rituximab treatment (Fig. 2). Conclusions: In MCL, molecular relapse is a harbinger of imminent clinical relapse, whereas continuous molecular remission is associated with prolonged disease-free survival (89% at 4 years) Rituximab preemptive treatment can reinduce molecular remission and may delay clinical relapse. Following molecular relapse, only Rituximab treated patients (6 of 8 evaluable) remain disease-free. FIG. 1. NORDIC NCL-2 PROTOCOL: RELAPSE-FREE SURVIVAL ACC. TO MOLECULAR STATUS POSTTRANSPALNT FIG. 1. NORDIC NCL-2 PROTOCOL: RELAPSE-FREE SURVIVAL ACC. TO MOLECULAR STATUS POSTTRANSPALNT FIG. 2. NORDIC NCL-2 PROTOCOL: RELAPSE-FREE SURVIVAL FROM TIME OF MOLECULAR RELAPSE. FIG. 2. NORDIC NCL-2 PROTOCOL: RELAPSE-FREE SURVIVAL FROM TIME OF MOLECULAR RELAPSE.