Despite recent advances in lymphoma treatment, mantle cell lymphoma (MCL) remains incurable and we are still unable to identify patients who will not benefit from the current standard-of-care. Here, we explore the prognostic value of recurrent genetic aberrations in diagnostic bone marrow (BM) specimens from 183 younger MCL patients from the Nordic MCL2 and MCL3 trials, which represent current standard-of-care regimens. In the univariate model, mutations of TP53 (11%) and NOTCH1 (4%), and deletions of TP53 (16%) and CDKN2A (20%) were significantly associated with inferior outcomes (together with MIPI, MIPI-c, Blastoid morphology and Ki67>30%); however, in multivariate analyses only TP53 mutations (HR=6.2, p<0.0001) retained prognostic impact for overall survival (OS), while TP53 mutations (HR=6.9, p<0.0001) and MIPI-c high-risk (HR=2.6, p=0.003) had independent prognostic impact on time to relapse. TP53-mutated cases had a dismal outcome with a median OS of 1.8 years and 50% relapsed at 1.0 years (compared to not reached (NR) and 12.7 years, respectively, for TP53-unmutated cases, p30%, blastoid morphology, MIPI high-risk and inferior responses to both induction- and high-dose chemotherapy. In conclusion, we show that TP53 mutations identify a phenotypically distinct and highly aggressive form of MCL with poor or no response to regimens including cytarabine, rituximab and autologous stem-cell transplant (ASCT). We suggest that MCL patients should be stratified according to TP53 status, and that patients with TP53 mutations should be considered for experimental frontline trials exploring novel agents. Key points The intensified standard-of-care regimens for younger MCL patients do not overcome the deleterious effects of TP53 mutations. MCLs with TP53 mutations should be considered for alternative frontline treatment.

The main objectives of the present study were to monitor minimal residual disease (MRD) in the bone marrow of patients with mantle cell lymphoma (MCL) to predict clinical relapse and guide preemptive treatment with rituximab. Among the patients enrolled in 2 prospective trials by the Nordic Lymphoma Group, 183 who had completed autologous stem cell transplantation (ASCT) and in whom an MRD marker had been obtained were included in our analysis. Fresh samples of bone marrow were analyzed for MRD by a combined standard nested and quantitative real-time PCR assay for Bcl-1/immunoglobulin heavy chain gene (IgH) and clonal IgH rearrangements. Significantly shorter progression-free survival (PFS) and overall survival (OS) was demonstrated for patients who were MRD positive pre-ASCT (54 patients) or in the first analysis post-ASCT (23 patients). The median PFS was only 20 months in those who were MRD-positive in the first sample post-ASCT, compared with 142 months in the MRD-negative group (P < .0001). OS was 75% at 10 years and median not reached in the MRD-negative group, compared with only 35 months in the MRD-positive group (P < .0001). Of the 86 patients (47%) who remained in continuous molecular remission, 73% were still in clinical remission after 10 years. For all patients, the median time from ASCT to first molecular relapse was 55 months, with a continuous occurrence of late molecular relapses. Fifty-eight patients who experienced MRD relapse received rituximab as preemptive treatment on 1 or more occasions, and in this group, the median time from first molecular relapse to clinical relapse was 55 months. In most cases, rituximab converted patients to MRD negativity (87%), but many patients became MRD-positive again later during follow-up (69%). By multivariate analysis, high-risk Mantle Cell Lymphoma International Prognostic Index score and positive MRD status pre-ASCT predicted early molecular relapse. In conclusion, preemptive rituximab treatment converts patients to MRD negativity and likely postpones clinical relapse. Molecular monitoring offers an opportunity to select some patients for therapeutic intervention and to avoid unnecessary treatment in others. MRD-positive patients in the first analysis post-ASCT have a dismal prognosis and thus are in need of novel strategies.

Eskelund et al examined clonal hematopoiesis (CH) in a cohort of patients with mantle cell lymphoma (MCL) treated with first-line chemotherapy and autologous stem cell transplantation. In young, good-risk MCL patients, CH after first-line therapy arises almost entirely from preexisting clones, stabilizes after a period of expansion posttransplantation, and does not negatively impact survival.