Treatment of mantle cell lymphoma (MCL) has long split by transplant eligibility: intensive chemoimmunotherapy and autologous stem cell transplantation (ASCT) for younger, fit patients, and less intensive chemotherapy-based regimens for the rest. This split has never matched the biology of the disease. Patients with similar clinical characteristics can have markedly different outcomes, and those with high-risk molecular features may relapse despite aggressive treatment.
Bruton tyrosine kinase (BTK) inhibitors, BCL-2 inhibitors, and cellular immunotherapies are changing how treatment is chosen. Recent randomized trials have questioned the need for routine ASCT, and the phase III MANGROVE trial has shown superior progression-free survival with a chemotherapy-free regimen over established chemoimmunotherapy. The central consideration is now which patients can achieve durable control without chemotherapy, which need more effective targeted combinations, and how biological risk and molecular response can guide those decisions.
MANGROVE: A Chemotherapy-Free Regimen Improves PFS
MANGROVE is a global, open-label trial that enrolled 510 previously untreated patients at 157 centers, mainly a population unsuitable for intensive transplant-based treatment. Patients received zanubrutinib plus rituximab or six cycles of bendamustine plus rituximab. Zanubrutinib was given at 160 mg twice daily, first with rituximab and then as monotherapy until progression or unacceptable toxicity.
The trial met its primary endpoint of independently assessed PFS. Zanubrutinib plus rituximab reduced the relative risk of progression or death by 43% (hazard ratio 0.57). Earlier frontline studies showed the value of adding targeted agents to chemotherapy. MANGROVE tested whether chemotherapy could be replaced.
In the phase III ECHO trial, adding acalabrutinib to bendamustine plus rituximab improved PFS in transplant-ineligible patients, and the regimen received FDA approval in January 2025. Both studies support BTK inhibition in frontline management.
On November 4, 2026, the FDA granted Priority Review to the supplemental application for zanubrutinib plus rituximab in previously untreated MCL. Approval would give the United States a specifically indicated chemotherapy-free, BTK inhibitor-based first-line option.
The MANGROVE results remain company-reported until detailed data are presented at the December 2026 American Society of Hematology Annual Meeting. Overall survival data were immature at the initial analysis, so longer follow-up is needed to judge the durability of the PFS benefit and its wider consequences.
Treatment Duration
Bendamustine plus rituximab is given for a defined period, whereas zanubrutinib in MANGROVE continues until progression or unacceptable toxicity. Patients exchange cytotoxic chemotherapy for prolonged inhibition of B-cell receptor signaling.
Bendamustine can cause substantial myelosuppression, infections, and prolonged immune suppression. Continuous BTK inhibition avoids conventional chemotherapy but adds cumulative risks: bleeding, infections, cytopenias, cardiovascular complications, and discontinuation because of adverse events. Initial MANGROVE safety findings were consistent with the established profiles of zanubrutinib and rituximab, with no new signals. Comparative data on serious infections, discontinuations, patient-reported outcomes, and long-term tolerability are needed.
Indefinite therapy in patients with sustained remission also carries ongoing toxicity, drug interactions, financial cost, and the demands of long-term adherence. Fixed-duration chemotherapy-free combinations are therefore a priority. Agents with complementary mechanisms may produce deeper molecular responses and allow discontinuation in selected patients. Stopping after a deep response requires prospective evidence that remission holds without therapy. PFS on continuous treatment and treatment-free remission are different outcomes, and both belong in the evaluation of chemotherapy-free strategies.
Biological Risk: Prognostic Markers Need Predictive Evidence
MCL ranges from indolent disease to rapidly progressive lymphoma. Some patients with asymptomatic, low-proliferation disease can safely be observed, while others need prompt treatment and remain at high risk of early progression.
The Mantle Cell Lymphoma International Prognostic Index combines age, performance status, lactate dehydrogenase, and white blood cell count. Ki-67 proliferation, TP53 alterations, and blastoid or pleomorphic morphology add information. TP53 mutation has the strongest prognostic weight.
It is associated with resistance to conventional chemoimmunotherapy and poor outcomes after intensive treatment, including ASCT. Current recommendations from the European Society for Blood and Marrow Transplantation (EBMT) describe a median overall survival below three years in TP53-mutated MCL treated with conventional chemoimmunotherapy-based approaches, with or without ASCT. High Ki-67, adverse morphology, and other molecular abnormalities also mark higher risk, with effects that differ in size and may overlap.
These markers identify patients likely to fail treatment, but choosing an alternative therapy needs further evidence. A prognostic marker predicts outcome, and a predictive marker identifies differential benefit from a specific treatment. TP53 mutation justifies testing approaches that don’t depend on chemotherapy.
A regimen effective across a whole trial population may not give equally durable control in aggressive molecular disease, and patients with favorable biology may achieve prolonged remission without more intensive treatment. Risk adaptation means matching strategy to biology, supported by prospective evidence of benefit in defined subgroups.
TP53-Mutated MCL
The BOVen regimen (zanubrutinib, obinutuzumab, and venetoclax) has been studied in previously untreated TP53-mutated MCL. It combines BTK inhibition, BCL-2 inhibition, and CD20-directed antibody therapy to produce deeper responses without chemotherapy. Early findings have been encouraging. The study was small and nonrandomized, and long-term comparative evidence is limited, so no conclusion about a survival gain over alternatives is possible.
An initial response isn’t enough if resistant clones persist and drive early progression, so chemotherapy-free treatment in this subgroup may need greater biological intensity through combinations. In standard-risk disease, the same approach could reduce treatment exposure. The aims differ: better control in high-risk MCL, less toxicity in highly treatment-sensitive disease.
The overall PFS benefit in MANGROVE can’t establish the effectiveness of zanubrutinib plus rituximab in TP53-mutated, blastoid, or highly proliferative MCL. Detailed subgroup results are needed.
Linking Molecular Response to Treatment Duration
MRD measures lymphoma burden below the detection threshold of clinical evaluation and imaging. A patient in deep molecular remission after a targeted combination could be a candidate for discontinuation in a prospective trial.
MRD negativity after intensive chemoimmunotherapy, after BTK inhibitor-based treatment, and during a BCL-2 inhibitor-containing combination may not carry the same implications for relapse. Assay sensitivity, timing of assessment, and the compartment sampled also affect interpretation.
Prospective trials need to test whether MRD-guided discontinuation, intensification, or maintenance modification beats predefined strategies. For chemotherapy-free regimens, the most consequential question may be whether sustained molecular remission supports safe, time-limited treatment without compromising long-term control.
Autologous Transplantation
Intensive cytarabine-containing chemoimmunotherapy followed by ASCT has been the standard first-line approach for younger, fit patients. In the phase III TRIANGLE trial, adding ibrutinib to frontline treatment improved outcomes and called into question the added benefit of ASCT when BTK inhibition is included. Longer follow-up is needed, particularly after maintenance ends and to clarify if patients with adverse biological features benefit from transplant consolidation.
The randomized ECOG-ACRIN EA4151 trial suggests that response depth may inform transplant decisions. In patients in complete remission with undetectable MRD after induction, ASCT followed by rituximab maintenance showed no clear added benefit. The 2026 EBMT recommendations accordingly support considering omission of ASCT in standard-risk patients receiving BTK inhibitor-containing induction, especially when MRD is undetectable at a sensitivity of 10⁻⁶. The decision is more complex in high-risk disease or with persistent MRD.
Cellular Immunotherapy: Established in Relapse, Investigational First Line
CD19-directed CAR T-cell therapies produce deep responses after prior systemic treatment, including BTK inhibitor exposure, which has prompted study of earlier use in high-risk disease. EBMT recommendations limit first-line CAR T-cell therapy to clinical trials and keep it as an established option in later lines. Evidence that it overcomes adverse molecular features is mixed, and not every patient achieves a durable remission.
Bispecific antibodies and newer cellular platforms may widen options, but their sequencing with BTK inhibitors, BCL-2 inhibitors, and other targeted therapies is under investigation. Early progression after frontline therapy carries poor survival, and patients with rapidly progressive lymphoma may not reach subsequent treatment. Earlier immunotherapy in selected high-risk patients therefore warrants prospective testing, weighed against the toxicity and logistical demands of cellular therapy.
First-Line Strategy: Individualization
In indolent disease, the priority is to avoid treatment until clinically necessary. In standard-risk MCL, chemotherapy-free therapy can maintain disease control with less cytotoxic exposure. In high-risk disease, particularly with TP53 alterations, the priority is to test more effective targeted combinations and earlier immunotherapy. Molecular-response thresholds and the interventions tied to them remain unvalidated for each therapeutic strategy.
MANGROVE shows that a chemotherapy-free regimen can outperform established chemoimmunotherapy in the population studied. Next steps are prospective biological risk stratification, standardized MRD assessment, and follow-up after treatment discontinuation, with overall survival, serious infections, cumulative toxicity, quality of life, and treatment-free intervals reported alongside PFS.
References
1. Glimelius I, Nikkarinen A, Meriranta L, Husby S, Pott C. The Lancet Haematology. 2026. DOI: 10.1016/S2352-3026(26)00127-4.
2. Dreger P, et al. Bone Marrow Transplantation. 2026;61:1151–1161.
3. BeOne Medicines. Phase III MANGROVE trial (NCT04002297). November 4, 2026.
