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Abstract: Obinutuzumab (O) and rituximab (R) are 2 CD antibodies that have never been compared in a prospective randomized trial of mantle cell lymphoma (MCL). Herein, we report the long-term outcome of the LyMa-101 trial, in which newly diagnosed patients with MCL were treated with chemotherapy plus O before transplantation, followed by O maintenance (O group). We then compared these patients with those treated with the same treatment design with R instead of O (R group). A propensity score matching (PSM) was used to compare the 2 populations (O vs R groups) in terms of measurable residual disease (MRD) at the end of induction (EOI), progression-free survival (PFS), and overall survival (OS). In LyMa-101, the estimated 5-year PFS and OS after inclusion (n = 85) were 83.4% (95% confidence interval [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%; χ2, P = .007). PSM resulted in 2 sets of 82 patients with comparable characteristics at inclusion. From treatment initiation, the O group had a longer estimated 5-year PFS (P = .029; 82.8% vs 66.6%; hazard ratio [HR], 1.99; 95% confidence interval (CI), 1.05-3.76) and OS (P = .039; 86.4% vs 71.4%; HR, 2.08; 95% CI, 1.01-4.16) compared with the R group. Causes of death were comparable in the 2 groups, the most common cause being lymphoma. O before transplantation and in maintenance provides better disease control and enhances PFS and OS compared with R in transplant-eligible patients with MCL. These trials were registered at www.clinicaltrials.gov as #NCT00921414 and NCT02896582., (© 2024 American Society of Hematology. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned coprimary or secondary analyses are not yet available. Clinical trial updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported. The LYMA trial demonstrated the benefit of rituximab maintenance (RM) in first-line young patients with mantle-cell lymphoma. In this prolonged follow-up of 7.5 years (95% CI, 7.4 to 7.7) from inclusion, the median progression-free survival (PFS) and overall survival (OS) for the full population were not reached (NR) with a 7-year PFS of 55.5% (95% CI, 49.5 to 61) and OS of 69.5% (95% CI, 63.8 to 74.5). The EFS remained statistically superior in favor of RM (median NR v 5.8 years, P < .0001; HR, 0.39 [95% CI, 0.52 to 0.6] and 7-year estimate, 76.2% versus 46% for RM and observation, respectively). Similarly, RM prolonged PFS (estimated PFS at 7 years, 78.5% v 47.4% and HR, 0.36 [95% CI, 0.23 to 0.56] for RM and observation, respectively, P < .0001). The 7-year OS estimate was 83.2% versus 72.2%, respectively ( P = .088, HR, 0.63 [95% CI, 0.37 to 1.08]). Cause of death was not significantly distinct between the two groups, with lymphoma being the leading cause with a very low rate of infection-related death. Overall, the PFS benefit of RM after autologous stem cell transplantation remains after 7-year follow-up, and RM was not associated with an increase in infection-related mortality, making this strategy a safe standard of care with long-term follow-up.

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported. In 2004, the European Mantle Cell Lymphoma (MCL) Network initiated the randomized open-label, phase III MCL Younger trial for first-line treatment of patients with advanced-stage MCL, age < 66 years, comparing an alternating rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone/rituximab plus dexamethasone, high-dose cytarabine, and cisplatin (R-CHOP/R-DHAP) induction followed by high-dose cytarabine-containing myeloablative radiochemotherapy conditioning and autologous peripheral blood stem-cell transplantation (R-DHAP arm) to R-CHOP with standard myeloablative radiochemotherapy and autologous stem-cell transplantation (R-CHOP arm). After a median follow-up of 10.6 years, the time to treatment failure was still significantly improved in the R-DHAP versus R-CHOP arms (medians 8.4 v 3.9 years, 5-/10-year rates 64%/46% v 41%/25%, P = .038, hazard ratio, 0.59). Median overall survival (OS) was not reached in the R-DHAP arm versus 11.3 years in R-CHOP arm (5-/10-year rates, 76%/60% v 69%/55%, P = .12). The unadjusted OS hazard ratios (0.80 [95% CI, 0.61 to 1.06], P = .12) reached significance when adjusted for Mantle Cell Lymphoma International Prognostic Index (MIPI) and MIPI + Ki-67 (MIPI-c) (0.74; 95% CI, 0.56 to 0.98; P = .038 and .60; 95% CI, 0.41 to 0.87; P = .0066). The incidence of secondary hematologic malignancies tended to be higher in the R-DHAP arm (4.5% v 1.4% at 10 years). With mature long-term data, we confirm the previously observed substantially prolonged time to treatment failure and, for the first time to our knowledge, show an improvement of OS. Some patients with MCL may be cured.

Quantification of minimal residual disease may guide therapeutic strategies in mantle cell lymphoma. While multiparameter flow cytometry is used for diagnosis, the gold standard method for minimal residual disease analysis is real-time quantitative polymerase chain reaction (RQ-PCR). In this European Mantle Cell Lymphoma network (EU-MCL) pilot study, we compared flow cytometry with RQ-PCR for minimal residual disease detection. Of 113 patients with at least one minimal residual disease sample, RQ-PCR was applicable in 97 (86%). A total of 284 minimal residual disease samples from 61 patients were analyzed in parallel by flow cytometry and RQ-PCR. A single, 8-color, 10-antibody flow cytometry tube allowed specific minimal residual disease assessment in all patients, with a robust sensitivity of 0.01%. Using this cut-off level, the true-positive-rate of flow cytometry with respect to RQ-PCR was 80%, whereas the true-negative-rate was 92%. As expected, RQ-PCR frequently detected positivity below this 0.01% threshold, which is insufficiently sensitive for prognostic evaluation and would ideally be replaced with robust quantification down to a 0.001% (10-5) threshold. In 10 relapsing patients, the transition from negative to positive by RQ-PCR (median 22.5 months before relapse) nearly always preceded transition by flow cytometry (4.5 months), but transition to RQ-PCR positivity above 0.01% (5 months) was simultaneous. Pre-emptive rituximab treatment of 2 patients at minimal residual disease relapse allowed re-establishment of molecular and phenotypic complete remission. Flow cytometry minimal residual disease is a complementary approach to RQ-PCR and a promising tool in individual mantle cell lymphoma therapeutic management. (clinicaltrials identifiers: 00209209 and 00209222)., (Copyright© Ferrata Storti Foundation.)

Although the overall survival has improved significantly in mantle cell lymphoma, relapsed disease remains a challenge. It has been demonstrated that high-dose cytarabine- and rituximab-containing regimens in induction improve response rate before autologous stem cell transplantation. This therapeutic strategy performed in first-line therapy improves significantly both progression-free survival and overall survival and has emerged as a new standard of care in younger patients. The role of allogeneic stem cell transplantation and its place in the treatment algorithm is not fully established, but may be a curative strategy. However, new therapeutic strategies such as maintenance/preemptive therapy or novel targeted therapies may challenge and change the indications of stem cell transplantation. This review will discuss the role of stem cell transplantation in mantle cell lymphoma and how emerging treatment strategies and novel therapies may challenge the current paradigms of therapy.