Ibrutinib, obinutuzumab, and venetoclax in relapsed and untreated patients with mantle cell lymphoma: a phase 1/2 trial

Acalabrutinib plus venetoclax and rituximab in treatment-naive mantle cell lymphoma: 2-year safety and efficacy analysis

ABSTRACT

This phase 1b study evaluated safety and efficacy of acalabrutinib, venetoclax, and rituximab (AVR) in treatment-naive mantle cell lymphoma (TN MCL). Patients received acalabrutinib from cycle 1 until progressive disease (PD) or undue toxicity, rituximab for 6 cycles with maintenance every other cycle through cycle 24 or until PD, and venetoclax, beginning at cycle 2, for 24 cycles. Twenty-one patients were enrolled; 95.2% completed induction (6 AVR cycles) and 47.6% continued acalabrutinib maintenance. Thirteen (61.9%) patients had grade 3-4 adverse events (AEs), most commonly neutropenia (33.3%). Seven (33.3%) patients had COVID-19 infection (6 [28.6%] serious AEs and 5 [23.8%] deaths, all among unvaccinated patients). There was no grade ≥3 atrial fibrillation, ventricular tachyarrhythmias, major hemorrhages, or tumor lysis syndrome. Overall response rate (ORR) was 100% (95% CI, 83.9-100.0) with 71.4% complete response. With median follow-up of 27.8 months, median progression-free survival (PFS) and overall survival (OS) were not reached. PFS rates at 1 and 2 years were 90.5% (95% CI, 67.0-97.5) and 63.2% (95% CI, 34.7-82.0), respectively; both were 95% after censoring COVID-19 deaths. OS rates at 1 and 2 years were 95.2% (95% CI, 70.7-99.3) and 75.2% (95% CI, 50.3-88.9), respectively; both were 100% after censoring COVID-19 deaths. Overall, 87.5% of patients with available minimal residual disease (MRD) data achieved MRD negativity (10-6; next-generation sequencing) during treatment. AVR represents a chemotherapy-free regimen for TN MCL and resulted in high ORR and high rates of MRD negativity. The trial was registered at www.ClinicalTrials.gov as #NCT02717624.

Dismantling relapsed/refractory mantle cell lymphoma

Despite recent therapeutic advancements in the general field of non-Hodgkin lymphoma, effective treatment of relapsed or refractory (R/R) mantle cell lymphoma (MCL) remains a challenge. The development of Bruton tyrosine kinase (BTK) inhibitors has revolutionized the field and these agents are now the mainstay of R/R MCL management. However, BTK inhibitors are not curative, and as they are increasingly being incorporated into frontline regimens, the shifting treatment landscape for R/R disease presents new challenges. Here we review data for commonly employed treatment strategies including BTK inhibitors, the BCL2-inhibitor venetoclax, lenalidomide-based regimens, and chimeric antigen receptor T-cell therapy. We additionally review data for promising novel agents including antibody-drug conjugates and bispecific antibodies before highlighting some emerging targeted agents that continue to bring promise for improved outcomes in R/R MCL.

Minimal residual disease detection in lymphoma: methods, procedures and clinical significance

Lymphoma is a highly heterogeneous lymphohematopoietic tumor. As our understanding of the biological and pathological characteristics of lymphoma improves, we are identifying an increasing number of lymphoma subtypes. Genotyping has enhanced our ability to diagnose, treat, and monitor the prognosis of lymphoma. Despite significant improvements in treatment effectiveness, traditional methods for assessing disease response and monitoring prognosis are imperfect, and there is no significant improvement in overall remission rates for lymphoma patients. Minimal Residual Disease (MRD) is often indicative of refractory disease or early relapse. For lymphoma patients, personalized MRD monitoring techniques offer an efficient means to estimate disease remission levels, predict early relapse risk, and assess the effectiveness of new drug regimens. In this review, we delve into the MRD procedures in lymphoma, including sample selection and requirements, detection methods and their limitations and advantages, result interpretation. Besides, we also introduce the clinical applications of MRD detection in lymphoma.

Management of relapsed/refractory mantle cell lymphoma

In this review we summarize the current evidence describing the management of patients with relapsed/refractory MCL and outline the various novel therapeutics that have been developed over the past two decades. We also describe how overall response rates, complete response rates, duration of responses, and life expectancy have dramatically increased with the introduction of novel therapies, particularly covalent Bruton Tyrosine Kinase inhibitors (BTKi) and chimeric antigen receptor T-cell (CAR-T) therapy. The most recent emerging options for patients with progressive disease following BTKi or CAR-T, including non-covalent BTKi, antibody-drug conjugates, Bcl-2 inhibitors, and bispecific antibodies, may further improve response rates and outcomes. Future directions should focus on identifying the best sequencing and/or combinations of the increasingly available treatment options while prioritizing strategies with curative potential.

SOHO State of the Art Updates and Next Questions: Treatment Evolution of Mantle Cell Lymphoma: Navigating the Different Entities and Biological Heterogeneity of Mantle Cell Lymphoma in 2024

Progress in mantle cell lymphoma (MCL) has led to significant improvement in outcomes of patients even in the real world (RW) setting albeit to a lesser degree. In parallel to the demonstration of benefit using combination therapy with rituximab plus high-dose cytarabine (R-AraC) as well as dose intensive therapy-autologous stem cell transplantation (DIT-ASCT) consolidation and maintenance, it became clear over the last 2 decades that MCL is a highly heterogenous disease at the molecular level, explaining differences observed in clinical behavior and response to therapy. While clinical prognostic factors and models have helped stratify patients with distinct outcomes, they failed to help guide therapy. The identification of molecular high-risk (HR) features, in particular, but not only, p53 aberrations (including mutations and deletions [del]), as well as complex karyotype (CK), has allowed to identify subsets of patients with poorer outcomes (median overall survival [OS] <2 years) regardless of conventional therapies used. The constant pattern of relapse seen in MCL has fueled sustained and productive efforts, with 7 novel agents approved in the United States (US), showing high and durable efficacy even in HR and chemo-refractory patients and likely curing a subset of patients in the relapsed or refractory (R/R) setting. Progress in diagnostics, in particular next-generation sequencing (NGS), which is accessible in routine practice nowadays, can help recognize patients with HR features, well beyond MIPI or Ki-67 prognostication, although the impact on decision making is still unclear. The era of integrating novel agents into our prior standard of care (SOC) has begun with a confirmed benefit, for example, ibrutinib (Ib) in the TRIANGLE study, defining the first new potential SOC in younger patients in over 30 years. Expanding on novel agents, either in combination, sequentially or to replace chemotherapy altogether, using biological doublets or triplets has led to a median progression-free survival (PFS) in excess of 72 months, certainly competitive with prior SOC and will continue to reshape the management of MCL patients. Achieving minimal residual disease negative (MRD-ve) status is becoming a new endpoint in MCL, and customizing maintenance and/or de-escalation/consolidation strategies is within reach, although it will require prospective, built-in MRD-based approaches, with the goal of eliminating subclinical disease and not simply delaying time to relapse. Taking into account the biological diversity of MCL is now feasible in routine clinical practice and has already helped recognize what not to do for HR patients (i.e., avoid intensive induction chemotherapy and/or ASCT for p53 mutated patients) as well as identify promising novel options. Ongoing and future work will help expand on these dedicated approaches, to further improve the management and outcomes of all MCL patients.

Combination of BCL-2 inhibitors and immunotherapy: a promising therapeutic strategy for hematological malignancies

The rapid development of high-throughput sequencing in recent years has facilitated great progress in the molecular-targeted therapy of hematological malignancies, including leukemia, lymphoma, and multiple myeloma. BCL-2 inhibitors are among the most important molecular-targeted agents. Immunotherapy for hematologic malignancy has rapidly increased in popularity in recent years and has been proven to improve the overall survival rate. However, few clinical studies have investigated combination therapy with BCL-2 inhibitors and immunotherapies, such as immune molecule-targeted drugs or immune cell adoptive therapy. In this review, we discuss the drug discovery process, current clinical application status, and resistance and tolerance issues associated with BCL-2 inhibitors. We emphasize their important role in regulating the immune system and propose that the combination of BCL-2 inhibitors with immunotherapy may be one of the most promising treatment methods for hematologic malignancies.

Obinutuzumab vs rituximab for transplant-eligible patients with mantle cell lymphoma

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.

Blockage of BCL-XL overcomes venetoclax resistance across BCL2+ lymphoid malignancies irrespective of BIM status

ABSTRACT

Venetoclax (VEN), a B-cell lymphoma 2 (BCL2) inhibitor, has a promising single-agent activity in mantle cell lymphoma (MCL), acute lymphoblastic leukemia (ALL), and large BCLs, but remissions were generally short, which call for rational drug combinations. Using a panel of 21 lymphoma and leukemia cell lines and 28 primary samples, we demonstrated strong synergy between VEN and A1155463, a BCL-XL inhibitor. Immunoprecipitation experiments and studies on clones with knockout of expression or transgenic expression of BCL-XL confirmed its key role in mediating inherent and acquired VEN resistance. Of note, the VEN and A1155463 combination was synthetically lethal even in the cell lines with lack of expression of the proapoptotic BCL2L11/BIM and in the derived clones with genetic knockout of BCL2L11/BIM. This is clinically important because BCL2L11/BIM deletion, downregulation, or sequestration results in VEN resistance. Immunoprecipitation experiments further suggested that the proapoptotic effector BAX belongs to principal mediators of the VEN and A1155463 mode of action in the BIM-deficient cells. Lastly, the efficacy of the new proapoptotic combination was confirmed in vivo on a panel of 9 patient-derived lymphoma xenografts models including MCL (n = 3), B-ALL (n = 2), T-ALL (n = 1), and diffuse large BCL (n = 3). Because continuous inhibition of BCL-XL causes thrombocytopenia, we proposed and tested an interrupted 4 days on/3 days off treatment regimen, which retained the desired antitumor synergy with manageable platelet toxicity. The proposed VEN and A1155463 combination represents an innovative chemotherapy-free regimen with significant preclinical activity across diverse BCL2+ hematologic malignancies irrespective of the BCL2L11/BIM status.

N-acetyltransferase 10 facilitates tumorigenesis of diffuse large B-cell lymphoma by regulating AMPK/mTOR signalling through N4-acetylcytidine modification of SLC30A9

BACKGROUND

Accumulating studies suggested that posttranscriptional modifications exert a vital role in the tumorigenesis of diffuse large B-cell lymphoma (DLBCL). N4-acetylcytidine (ac4C) modification, catalyzed by the N-acetyltransferase 10 (NAT10), was a novel type of chemical modification that improves translation efficiency and mRNA stability.

METHODS

GEO databases and clinical samples were used to explore the expression and clinical value of NAT10 in DLBCL. CRISPER/Cas9-mediated knockout of NAT10 was performed to determine the biological functions of NAT10 in DLBCL. RNA sequencing, acetylated RNA immunoprecipitation sequencing (acRIP-seq), LC-MS/MS, RNA immunoprecipitation (RIP)-qPCR and RNA stability assays were performed to explore the mechanism by which NAT10 contributed to DLBCL progression.

RESULTS

Here, we demonstrated that NAT10-mediated ac4C modification regulated the occurrence and progression of DLBCL. Dysregulated N-acetyltransferases expression was found in DLBCL samples. High expression of NAT10 was associated with poor prognosis of DLBCL patients. Deletion of NAT10 expression inhibited cell proliferation and induced G0/G1 phase arrest. Furthermore, knockout of NAT10 increased the sensitivity of DLBCL cells to ibrutinib. AcRIP-seq identified solute carrier family 30 member 9 (SLC30A9) as a downstream target of NAT10 in DLBCL. NAT10 regulated the mRNA stability of SLC30A9 in an ac4C-dependent manner. Genetic silencing of SLC30A9 suppressed DLBCL cell growth via regulating the activation of AMP-activated protein kinase (AMPK) pathway.

CONCLUSION

Collectively, these findings highlighted the essential role of ac4C RNA modification mediated by NAT10 in DLBCL, and provided insights into novel epigenetic-based therapeutic strategies.

Targeted Therapies in the Treatment of Mantle Cell Lymphoma

Mantle cell lymphoma (MCL) is a rare, heterogeneous B-cell non-Hodgkin's lymphoma. The standard front-line treatment utilizes chemotherapy, often followed by consolidation with an autologous hematopoietic cell transplant; however, in most patients, the lymphoma will recur and require subsequent treatments. Additionally, mantle cell lymphoma primarily affects older patients and is frequently chemotherapy-resistant, which has further fostered the necessity for new, chemotherapy-free treatment options. In the past decade, targeted therapies in mantle cell lymphoma have been practice-changing as the treatment paradigm shifts further away from relying primarily on cytotoxic agents. Here, we will review the pathophysiology of mantle cell lymphoma and discuss the emergence of targeted, chemotherapy-free treatments aimed at disrupting the abnormal biology driving its lymphomagenesis. Treatments targeting the constitutive activation of NF-kB, Bruton's Tyrosine Kinase signaling, and anti-apoptosis will be the primary focus as we discuss their clinical data and toxicities. Our review will also focus primarily on the emergence and use of targeted therapies in the relapsed/refractory setting but will also discuss the emergence of their use in front-line therapy and in combination with other agents.

Ibrutinib and venetoclax as primary therapy in symptomatic, treatment-naïve Waldenström macroglobulinemia

ABSTRACT

Concurrent Bruton tyrosine kinase and BCL2 inhibition has not yet been investigated in Waldenström macroglobulinemia (WM). We performed an investigator-initiated trial of ibrutinib and venetoclax in symptomatic treatment-naïve patients with MYD88-mutated WM. Patients received ibrutinib 420 mg once daily (cycle 1), followed by a ramp-up of venetoclax to 400 mg daily (cycle 2). The combination was then administered for 22 additional 4-week cycles. The attainment of very good partial response (VGPR) was the primary end point. Forty-five patients were enrolled in this study. The median baseline characteristics were as follows: age 67 years, serum IgM 43 g/L, and hemoglobin 102 g/L. Seventeen patients (38%) carried CXCR4 mutations. Nineteen patients (42%) achieved VGPR. Grade 3 or higher adverse events included neutropenia (38%), mucositis (9%), and tumor lysis syndrome (7%). Atrial fibrillation occurred in 3 (9%), and ventricular arrhythmia in 4 (9%) patients that included 2 grade 5 events. With a median follow-up of 24.4 months, the 24-month progression-free survival (PFS) and overall survival (OS) rates were 76% and 96%, respectively, and were not impacted by CXCR4 mutations. The median time on therapy was 10.2 months, and the median time after the end of therapy (EOT) was 13.3 months. Eleven of the 12 progression events occurred after EOT, and the 12-month PFS rates after EOT were 79%; 93% if VGPR was attained, and 69% for other patients (P = .12). Ibrutinib and venetoclax induced high VGPR rates and durable responses after EOT, although they were associated with a higher-than-expected rate of ventricular arrhythmia in patients with WM, leading to early study treatment termination. This trial was registered at www.clinicaltrials.gov as #NCT04273139.

Phase I study of bendamustine, rituximab, ibrutinib, and venetoclax in relapsed, refractory mantle cell lymphoma

This dose-finding study evaluated safety of venetoclax plus Bendamustine-Rituximab-Ibrutinib in relapsed/refractory MCL. Six 28-day cycles were administered in a 3 + 3 dose-escalation design. Dose level 1 (DL1) included Bendamustine 90 mg/m2 on day 1-2, Rituximab 375 mg/m2 on day 1, and Ibrutinib 560 mg daily. Venetoclax was dosed with ramp-up and at 400 mg starting in Cycle 2 for 5 days. The most common adverse events were thrombocytopenia (80%), constipation (60%), and fatigue (60%). Rare hematologic grade 3-4 AEs, 1 dose-limiting toxicity at DL1 (prolonged grade 3 thrombocytopenia), and delayed hematologic toxicity were observed. DL-1 with Bendamustine dose-reduced to 70 mg/m2 (n = 3) revealed no significant toxicity. The overall and complete response rates were both 80% (8/10). This study underscored that venetoclax combined with chemoimmunotherapy is complicated by hematologic toxicity, limiting future development. Although a maximum tolerated dose was not formally established given early study closure, this study demonstrated preliminary tolerability and efficacy of Bendamustine-Rituximab-Ibrutinib-Venetoclax at DL-1.

MRD-driven treatment with venetoclax-R2 in mantle cell lymphoma: the Nordic Lymphoma Group MCL7 VALERIA trial

ABSTRACT

Despite improvements in treatment of mantle cell lymphoma (MCL), most patients eventually relapse. In this multicenter phase 1b/2 trial, we evaluated safety and efficacy of minimal residual disease (MRD)-driven venetoclax, lenalidomide, and rituximab (venetoclax-R2) in relapsed/refractory (R/R) MCL and explored the feasibility of stopping treatment in molecular remission. The primary end point was overall response rate (ORR) at 6 months. After dose escalation, the recommended phase 2 dose was lenalidomide 20 mg daily, days 1 to 21; venetoclax 600 mg daily after ramp-up; and rituximab 375 mg/m2 weekly for 4 weeks, then every 8 weeks. MRD monitoring by RQ-PCR was performed every 3 months. When MRD-negativity in the blood was reached, treatment was continued for another 3 months; if MRD-negativity was then confirmed, treatment was stopped. In total, 59 patients were enrolled, with a median age of 73 years. At 6 months, the ORR was 63% (29 complete remission [CR], 8 partial remission [PR]), and 40% (4 CR, 2 PR) for patients previously failing a Bruton tyrosine kinase (BTK) inhibitor. Median progression-free survival (PFS) was 21 months, with median overall survival of 31 months. TP53 mutation was associated with inferior PFS (P < .01). Overall, 28 patients (48%) discontinued treatment in molecular remission, and 25 remain MRD negative after a median of 17.4 months. Hematological toxicity was frequent, with 52 of 59 (88%) patients with G3-4 neutropenia and 21 of 59 (36%) patients with G3-4 thrombocytopenia. To conclude, MRD-driven venetoclax-R2 is feasible and tolerable and shows efficacy in R/R MCL, also after BTK inhibitor failure. This trial was registered at www.ClinicalTrials.gov as #NCT03505944.

Novel treatment for mantle cell lymphoma - impact of BTK inhibitors and beyond

Mantle cell lymphoma (MCL) primarily affects older adults, accounting for 3-10% of all non-Hodgkin lymphoma (NHL) in western countries. The disease course of MCL is heterogenous; driven by clinical, cytogenetics, and molecular features that shape differences in outcomes, including proliferation index, MIPI scores, and mutational profile such as TP53 aberration. The advent of novel agents has fundamentally evolved the treatment landscape for MCL with treatment strategies that can now be more effectively tailored based on both patient- and disease-specific factors. In this review, we discuss the major classes of novel agents used for the treatment of MCL, focusing on efficacy and notable toxicities of BTK inhibitors. We further examine effective novel combination regimens and, lastly, discuss future directions for the evolution of targeted approaches for the treatment of MCL.

Recent advances in genomics and therapeutics in mantle cell lymphoma

Over the past decades, significant strides have been made in understanding the pathobiology, prognosis, and treatment options for mantle cell lymphoma (MCL). The heterogeneity observed in MCL's biology, genomics, and clinical manifestations, including indolent and aggressive forms, is intricately linked to factors such as the mutational status of the variable region of the immunoglobulin heavy chain gene, epigenetic profiling, and Sox11 expression. Several intriguing subtypes of MCL, such as Cyclin D1-negative MCL, in situ mantle cell neoplasm, CCND1/IGH FISH-negative MCL, and the impact of karyotypic complexity on prognosis, have been explored. Notably, recent immunochemotherapy regimens have yielded long-lasting remissions in select patients. The therapeutic landscape for MCL is continuously evolving, with a shift towards nonchemotherapeutic agents like ibrutinib, acalabrutinib, and venetoclax. The introduction of BTK inhibitors has brought about a transformative change in MCL treatment. Nevertheless, the challenge of resistance to BTK inhibitors persists, prompting ongoing efforts to discover strategies for overcoming this resistance. These strategies encompass non-covalent BTK inhibitors, immunomodulatory agents, BCL2 inhibitors, and CAR-T cell therapy, either as standalone treatments or in combination regimens. Furthermore, developing novel drugs holds promise for further improving the survival of patients with relapsed or refractory MCL. In this comprehensive review, we methodically encapsulate MCL's clinical and pathological attributes and the factors influencing prognosis. We also undertake an in-depth examination of stratified treatment alternatives. We investigate conceivable resistance mechanisms in MCL from a genetic standpoint and offer precise insights into various therapeutic approaches for relapsed or refractory MCL.

CARD11 gain of function upregulates BCL2A1 expression and promotes resistance to targeted therapies combination in B-cell lymphoma

A strategy combining targeted therapies is effective in B-cell lymphomas (BCL), such as mantle cell lymphoma (MCL), but acquired resistances remain a recurrent issue. In this study, we performed integrative longitudinal genomic and single-cell RNA-sequencing analyses of patients with MCL who were treated with targeted therapies against CD20, BCL2, and Bruton tyrosine kinase (OAsIs trial). We revealed the emergence of subclones with a selective advantage against OAsIs combination in vivo and showed that resistant cells were characterized by B-cell receptor (BCR)-independent overexpression of NF-κB1 target genes, especially owing to CARD11 mutations. Functional studies demonstrated that CARD11 gain of function not only resulted in BCR independence but also directly increased the transcription of the antiapoptotic BCL2A1, leading to resistance against venetoclax and OAsIs combination. Based on the transcriptional profile of OAsIs-resistant subclones, we designed a 16-gene resistance signature that was also predictive for patients with MCL who were treated with conventional chemotherapy, underlying a common escape mechanism. Among druggable strategies to inhibit CARD11-dependent NF-κB1 transduction, we evaluated the selective inhibition of its essential partner MALT1. We demonstrated that MALT1 protease inhibition led to a reduction in the expression of genes involved in OAsIs resistance, including BCL2A1. Consequently, MALT1 inhibition induced synergistic cell death in combination with BCL2 inhibition, irrespective of CARD11 mutational status, both in vitro and in vivo. Taken together, our study identified mechanisms of resistance to targeted therapies and provided a novel strategy to overcome resistance in aggressive BCL. The OAsIs trial was registered at www.clinicaltrials.gov #NCT02558816.

Current Advances and Future Strategies for BCL-2 Inhibitors: Potent Weapons against Cancers

Targeting the intrinsic apoptotic pathway regulated by B-cell lymphoma-2 (BCL-2) antiapoptotic proteins can overcome the evasion of apoptosis in cancer cells. BCL-2 inhibitors have evolved into an important means of treating cancers by inducing tumor cell apoptosis. As the most extensively investigated BCL-2 inhibitor, venetoclax is highly selective for BCL-2 and can effectively inhibit tumor survival. Its emergence and development have significantly influenced the therapeutic landscape of hematological malignancies, especially in chronic lymphocytic leukemia and acute myeloid leukemia, in which it has been clearly incorporated into the recommended treatment regimens. In addition, the considerable efficacy of venetoclax in combination with other agents has been demonstrated in relapsed and refractory multiple myeloma and certain lymphomas. Although venetoclax plays a prominent antitumor role in preclinical experiments and clinical trials, large individual differences in treatment outcomes have been characterized in real-world patient populations, and reduced drug sensitivity will lead to disease recurrence or progression. The therapeutic efficacy may vary widely in patients with different molecular characteristics, and key genetic mutations potentially result in differential sensitivities to venetoclax. The identification and validation of more novel biomarkers are required to accurately predict the effectiveness of BCL-2 inhibition therapy. Furthermore, we summarize the recent research progress relating to the use of BCL-2 inhibitors in solid tumor treatment and demonstrate that a wealth of preclinical models have shown promising results through combination therapies. The applications of venetoclax in solid tumors warrant further clinical investigation to define its prospects.

Combating relapsed and refractory Mantle cell lymphoma with novel therapeutic armamentarium: Recent advances and clinical prospects

Mantle cell lymphoma (MCL) is a rare, aggressive subtype of non-Hodgkin's lymphoma (NHL), accounting for 5% of all cases. Due to its virulence factor, it is an incurable disease and keeps relapsing despite an intensive treatment regimen. Advancements in research and drug discovery have shifted the treatment strategy from conventional chemotherapy to targeted agents and immunotherapies. The establishment of the role of Bruton tyrosine kinase led to the development of ibrutinib, a first-generation BTK inhibitor, and its successors. A conditioning regimen based immunotherapeutic agent like ibritumumob, has also demonstrated a viable response with a favorable toxicity profile. Brexucabtagene Autoleucel, the only approved CAR T-cell therapy, has proven advantageous for relapsed/refractory MCL in both children and adults. This article reviews certain therapies that could help update the current approach and summarizes a few miscellaneous agents, which, seldom studied in trials, could alleviate the regression observed in traditional therapies. DATA AVAILABILITY: The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

SOHO State of the Art Updates and Next Questions: Tailoring Upfront Therapy in Mantle Cell Lymphoma

In this article, we will review current strategies for the front-line management of mantle cell lymphoma, an uncommon and biologically and clinically heterogeneous subtype of non-Hodgkin lymphoma that remains incurable with current therapies. Patients invariably relapse with time, and as a result, treatment strategies involve persistent therapy over the course of months to years, including induction, consolidation, and maintenance. Topics discussed include the historical development of various chemoimmunotherapy backbones with continued modifications to maintain and improve efficacy while limiting off-target, off-tumor effects. Chemotherapy-free induction regimens were developed initially for elderly or less fit patients though are now being utilized for younger, transplant-eligible patients due to deeper, more prolonged remission durations with fewer toxicities. The historic paradigm of recommending autologous hematopoietic cell transplant for fit patients in complete or partial remission is now being challenged based in part on ongoing clinical trials in which minimal residual disease directed approaches influence the consolidation strategy for any particular individual. The addition of novel agents, namely first and second generation Bruton tyrosine kinase inhibitors as well as immunomodulatory drugs, BH3 mimetics, and type II glycoengineered anti-CD20 monoclonal antibodies have been tested in various combinations with or without immunochemotherapy. We will attempt to help the reader by systematically explaining and simplifying the various approaches for treating this complicated group of disorders.

Beyond Bruton's tyrosine kinase inhibitors in mantle cell lymphoma: bispecific antibodies, antibody-drug conjugates, CAR T-cells, and novel agents

Mantle cell lymphoma is a B cell non-Hodgkin lymphoma (NHL), representing 2-6% of all NHLs and characterized by overexpression of cyclin D1. The last decade has seen the development of many novel treatment approaches in MCL, most notably the class of Bruton's tyrosine kinase inhibitors (BTKi). BTKi has shown excellent outcomes for patients with relapsed or refractory MCL and is now being studied in the first-line setting. However, patients eventually progress on BTKi due to the development of resistance. Additionally, there is an alteration in the tumor microenvironment in these patients with varying biological and therapeutic implications. Hence, it is necessary to explore novel therapeutic strategies that can be effective in those who progressed on BTKi or potentially circumvent resistance. In this review, we provide a brief overview of BTKi, then discuss the various mechanisms of BTK resistance including the role of genetic alteration, cancer stem cells, tumor microenvironment, and adaptive reprogramming bypassing the effect of BTK inhibition, and then provide a comprehensive review of current and emerging therapeutic options beyond BTKi including novel agents, CAR T cells, bispecific antibodies, and antibody-drug conjugates.

Adding venetoclax to lenalidomide and rituximab is safe and effective in patients with untreated mantle cell lymphoma

Mantle cell lymphoma (MCL) is a rare, incurable hematological malignancy with a heterogeneous presentation and clinical course. A wide variety of chemotherapy-based regimens are currently used in patients who are untreated. Over the last several years, several targeted or small-molecule therapies have shown efficacy in the relapsed/refractory setting and have since been explored in the frontline setting. Lenalidomide plus rituximab was explored in a phase 2 study of 38 patients with MCL who were untreated and ineligible to receive transplantation, in which the combination produced durable remissions. We looked to build upon this regimen by adding venetoclax to the combination. We conducted a multicenter, open-label, nonrandomized, single-arm study to evaluate this combination. We enrolled 28 unselected patients with untreated disease irrespective of age, fitness, or risk factors. Lenalidomide was dosed at 20 mg daily from days 1 to 21 of each 28-day cycle. The dose of venetoclax was determined using the time-to-event continual reassessment method. Rituximab was dosed at 375 mg/m2 weekly, starting on cycle 1, day 1 until cycle 2, day 1. No dose-limiting toxicities were noted. All patients were treated with venetoclax at the maximum tolerated dose of 400 mg daily. The most common adverse events were neutropenia and thrombocytopenia. The overall and complete response rates were 96% and 86%, respectively. In total, 86% of patients achieved minimal residual disease undetectability via next-generation sequencing. The median overall and progression-free survivals were not reached. The combination of lenalidomide, rituximab, and venetoclax is a safe and effective regimen in patients with untreated MCL. This trial was registered at www.clinicaltrials.gov as #NCT03523975.

Dual Targeting of Apoptotic and Signaling Pathways in T-Lineage Acute Lymphoblastic Leukemia

PURPOSE

Relapsed T-acute lymphoblastic leukemia (T-ALL) has limited treatment options. We investigated mechanisms of resistance to BH3 mimetics in T-ALL to develop rational combination strategies. We also looked at the preclinical efficacy of NWP-0476, a novel BCL-2/BCL-xL inhibitor, as single agent and combination therapy in T-ALL.

EXPERIMENTAL DESIGN

We used BH3 profiling as a predictive tool for BH3 mimetic response in T-ALL. Using isogenic control, venetoclax-resistant (ven-R) and NWP-0476-resistant (NWP-R) cells, phosphokinase array was performed to identify differentially regulated signaling pathways.

RESULTS

Typical T-ALL cells had increased dependence on BCL-xL, whereas early T-precursor (ETP)-ALL cells had higher BCL-2 dependence for survival. BCL-2/BCL-xL dual inhibitors were effective against both subtypes of T-lineage ALL. A 71-protein human phosphokinase array showed increased LCK activity in ven-R cells, and increased ACK1 activity in ven-R and NWP-R cells. We hypothesized that pre-TCR and ACK1 signaling pathways are drivers of resistance to BCL-2 and BCL-xL inhibition, respectively. First, we silenced LCK gene in T-ALL cell lines, which resulted in increased sensitivity to BCL-2 inhibition. Mechanistically, LCK activated NF-κB pathway and the expression of BCL-xL. Silencing ACK1 gene resulted in increased sensitivity to both BCL-2 and BCL-xL inhibitors. ACK1 signaling upregulated AKT pathway, which inhibited the pro-apoptotic function of BAD. In a T-ALL patient-derived xenograft model, combination of NWP-0476 and dasatinib demonstrated synergy without major organ toxicity.

CONCLUSIONS

LCK and ACK1 signaling pathways are critical regulators of BH3 mimetic resistance in T-ALL. Combination of BH3 mimetics with tyrosine kinase inhibitors might be effective against relapsed T-ALL.

A multicenter analysis of the outcomes with venetoclax in patients with relapsed mantle cell lymphoma

To report the activity of venetoclax in patients with relapsed mantle cell lymphoma (MCL), we identified 81 patients treated with venetoclax monotherapy (n = 50, 62%) or in combination with a Bruton tyrosine kinase inhibitor (BTKi) (n = 16, 20%), an anti-CD20 monoclonal antibody (n = 11, 14%), or other active agents at 12 US academic medical centers. Patients had high-risk disease features including Ki67 >30% (61%), blastoid/pleomorphic histology (29%), complex karyotype (34%), and TP53 alterations (49%), and received a median of 3 prior treatments including BTKis in 91%. Venetoclax alone or in combination resulted in an overall response rate (ORR) of 40% and median progression-free (PFS) and overall survival (OS) of 3.7 and 12.5 months, respectively. The receipt of ≤3 prior treatments was associated with higher odds of response to venetoclax in a univariable analysis. In a multivariable analysis, having a high-risk Mantle Cell Lymphoma International Prognostic Index score before receiving venetoclax and disease relapse or progression within 24 months of diagnosis were associated with inferior OS whereas the use of venetoclax in combination was associated with superior OS. Although most patients (61%) had low risk for tumor lysis syndrome (TLS), 12.3% of patients developed TLS despite the implementation of several mitigation strategies. In conclusion, venetoclax resulted in good ORR but short PFS in patients with MCL who are at high risk, and may have a better role in earlier lines of treatment and/or in conation with other active agents. TLS remains an important risk in patients with MCL who initiate treatment with venetoclax.

Real-world treatment and outcome patterns of patients with mantle cell lymphoma in China: A large, multicenter retrospective analysis

BACKGROUND

Mantle cell lymphoma (MCL) is an uncommon heterogeneous subtype of B cell non-Hodgkin lymphoma, and clinical features in MCL appear regional characteristics. MCL treatment opinions are not uniform between countries or regions within Asia and China, and Asian patient-specific data for MCL treatment are fewer. The study aims to explore the clinical characteristics, treatment patterns and prognosis of MCL patients in China.

METHODS

A total of 805 patients diagnosed with MCL between April 1999 and December 2019 at 19 comprehensive hospitals in China were included in this retrospective analysis. Kaplan-Meier method coupled with the log-rank test was used for univariate analysis, and COX proportional hazards model was used for multivariate analysis (MVA). p < 0.05 was consided statistically significant. All outputs were produced using R version 4.1.0.

RESULTS

The median age of the cohort was 60.0 years with a male-to-female ratio of 3.36:1. Five-year progression-free survival (PFS) and overall survival (OS) rates were 30.9% and 65.0%, respectively. High-intermediate/high-risk group according to MIPI-c, without high-dose cytarabine, lack of Auto-SCT as consolidation and maintenance treatment and SD/PD in initial treatment remained statistically relevant to poor PFS on MVA, and ki67 ≥50%, B symptoms, high-intermediate/high risk group according to MIPI-c, without high-dose cytarabine, lack of maintenance treatment, SD/PD in initial treatment and relapse/refractory state were independently associated with poorer OS on MVA.

CONCLUSIONS

First-line high dose cytarabine exposure, auto-SCT as consolidation therapy obtained survival benefits in Chinese population. Our study further confirmed the value of maintenance treatment and explored the application of new drug treatment and bendamustine in R/R MCL patients.

DTRMWXHS-12, a novel Bruton tyrosine kinase inhibitor, in combination with everolimus and pomalidomide in patients with relapsed/refractory lymphomas: An open-label, multicenter, phase 1a/1b study

Preclinical studies have shown augmented activity when combining Bruton tyrosine kinase inhibitors (BTKi) with inhibitors of mammalian target of rapamycin (mTOR) and immunomodulatory agents (IMiD). We conducted a phase 1, open-label study at five centers in USA to evaluate the safety of triplet BTKi/mTOR/IMiD therapy. Eligible patients were adults aged 18 years or older with relapsed/refractory CLL, B cell NHL, or Hodgkin lymphoma. Our dose escalation study used an accelerated titration design and moved sequentially from single agent BTKi (DTRMWXHS-12), doublet (DTRMWXHS-12 + everolimus), and then to triplet therapy (DTRMWXHS-12 + everolimus + pomalidomide). All drugs were dosed once daily on days 1-21 of each 28-day cycle. The primary goal was to establish the recommended phase 2 dose of the triplet combination. Between September 27, 2016, and July 24, 2019, a total of 32 patients with a median age of 70 years (range 46 to 94 years) were enrolled. No MTD was identified for monotherapy and the doublet combination. The MTD for the triplet combination was determined to be DTRMWXHS-12 200 mg + everolimus 5 mg + pomalidomide 2 mg. Responses across all studied cohorts were seen in 13 of 32 (41.9%). Combining DTRMWXHS-12 with everolimus and pomalidomide is tolerable and shows clinical activity. Additional trials could confirm benefit of this all-oral combination therapy for relapsed/refractory lymphomas.

Role of Bcl-2 inhibition in myelodysplastic syndromes

Myelodysplasic syndromes (MDS) are diseases occurring mainly in the elderly population. Although hematopoietic stem cell transplantation is the only hope for cure, a majority of the patients suffering from MDS are too old or frail for intensive treatment regimens such as intensive chemotherapy and transplantation. The gold standard for those patients is currently treatment with hypomethylating agents, although real-life data could not reproduce the overall survival rates reported for the pivotal azacitidine phase III study. MDS treatment is often inspired by treatment for acute myeloid leukemia (AML). The new gold standard for elderly and frail patients not able to undergo intensive treatment regimens in AML is the combination of hypomethylating agents with venetoclax, a BCL-2 inhibitor that also showed excellent treatment outcomes in other hematological malignancies. In this review, we explain the rationale for the use of venetoclax in hematological malignancies, study outcomes available so far and the current knowledge of its use in MDS.

A novel patient-derived 3D model recapitulates mantle cell lymphoma lymph node signaling, immune profile and in vivo ibrutinib responses

Mantle cell lymphoma (MCL), a rare and aggressive B-cell non-Hodgkin lymphoma, mainly develops in the lymph node (LN) and creates a protective and immunosuppressive niche that facilitates tumor survival, proliferation and chemoresistance. To capture disease heterogeneity and tumor microenvironment (TME) cues, we have developed the first patient-derived MCL spheroids (MCL-PDLS) that recapitulate tumor oncogenic pathways and immune microenvironment in a multiplexed system that allows easy drug screening, including immunotherapies. MCL spheroids, integrated by tumor B cells, monocytes and autologous T-cells self-organize in disc-shaped structures, where B and T-cells maintain viability and proliferate, and monocytes differentiate into M2-like macrophages. RNA-seq analysis demonstrated that tumor cells recapitulate hallmarks of MCL-LN (proliferation, NF-kB and BCR), with T cells exhibiting an exhaustion profile (PD1, TIM-3 and TIGIT). MCL-PDLS reproduces in vivo responses to ibrutinib and demonstrates that combination of ibrutinib with nivolumab (anti-PD1) may be effective in ibrutinib-resistant cases by engaging an immune response with increased interferon gamma and granzyme B release. In conclusion, MCL-PDLS recapitulates specific MCL-LN features and in vivo responses to ibrutinib, representing a robust tool to study MCL interaction with the immune TME and to perform drug screening in a patient-derived system, advancing toward personalized therapeutic approaches.

Inhibition of casein kinase 2 sensitizes mantle cell lymphoma to venetoclax through MCL-1 downregulation

BCL-2 family proteins are frequently aberrantly expressed in mantle cell lymphoma (MCL). Recently, the BCL-2-specific inhibitor venetoclax has been approved by the US Food and Drug Administration for chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML). In MCL, venetoclax has shown promising efficacy in early clinical trials; however, a significant subset of patients is resistant. By conducting a kinome-centered CRISPR-Cas9 knockout sensitizer screen, we identified casein kinase 2 (CK2) as a major regulator of venetoclax resistance in MCL. Interestingly, CK2 is over-expressed in MCL and high CK2 expression is associated with poor patient survival. Targeting of CK2, either by inducible short hairpin RNA (shRNA)-mediated knockdown of CK2 or by the CK2-inhibitor silmitasertib, did not affect cell viability by itself, but strongly synergized with venetoclax in both MCL cell lines and primary samples, also if combined with ibrutinib. Furthermore, targeting of CK2 reduced MCL-1 levels, which involved impaired MCL-1 translation by inhibition of eIF4F complex assembly, without affecting BCL-2 and BCL-XL expression. Combined, this results in enhanced BCL-2 dependence and, consequently, venetoclax sensitization. In cocultures, targeting of CK2 overcame stroma-mediated venetoclax resistance of MCL cells. Taken together, our findings indicate that targeting of CK2 sensitizes MCL cells to venetoclax through downregulation of MCL-1. These novel insights provide a strong rationale for combining venetoclax with CK2 inhibition as therapeutic strategy for MCL patients.

How I manage mantle cell lymphoma: indolent versus aggressive disease

Mantle cell lymphoma (MCL) is a mature B-cell lymphoma with a variable clinical course and historically poor prognosis. Management is challenging in part due to the heterogeneity of the disease course, with indolent and aggressive subtypes now well recognised. Indolent MCL is often characterised by a leukaemic presentation, SOX11 negativity and low proliferation index (Ki-67). Aggressive MCL is characterised by rapid onset widespread lymphadenopathy, extra-nodal involvement, blastoid or pleomorphic histology and high Ki-67. Tumour protein p53 (TP53) aberrations in aggressive MCL are recognised with clear negative impact on survival. Until recently, trials have not addressed these specific subtypes separately. With the increasing availability of targeted novel agents and cellular therapies, the treatment landscape is constantly evolving. In this review, we describe the clinical presentation, biological factors, and specific management considerations of both indolent and aggressive MCL and discuss current and potential future evidence which may help move to a more personalised approach.

Personalized approaches for treatment-naïve mantle cell lymphoma

INTRODUCTION

Mantle cell lymphoma (MCL) can have diverse disease presentations, which vary in aggressiveness and prognosis, and can occur in patients with varying ability to tolerate therapy. Additionally, the options for treatment of MCL have expanded rapidly in the last decade, translating to improved outcome for patients.

AREAS COVERED

We review the initial evaluation of patients with MCL, identifying disease- and patient-specific prognostic factors, along with personalized therapies for patients with MCL. Specific scenarios include indolent and limited-stage MCL, advanced-stage disease in transplant-eligible and ineligible patients, and high-risk TP53 mutant disease. Ongoing trials and future directions in MCL treatment are also highlighted.

EXPERT OPINION

Given the wide array of disease and patient presentations with MCL, a personalized therapeutic approach is needed to optimize outcomes. The best therapeutic strategy should incorporate disease prognostic factors, patient status and comorbidities, goals of care, and response to treatment.

Treatment approaches for patients with TP53-mutated mantle cell lymphoma

Mantle cell lymphoma is an uncommon subtype of lymphoma characterised by clinical and biological heterogeneity. Although most patients with mantle cell lymphoma have durable responses after chemoimmunotherapy, there is a need to prospectively identify high-risk subsets of patients for whom disease control with standard chemotherapy will be short lived. Among the available prognostic factors, TP53 mutations are uniquely informative owing to their strong association with early disease progression and death among patients receiving conventional chemoimmunotherapy, with the highest negative prognostic value compared with other established risk indicators, including the mantle cell lymphoma international prognostic index, histological features, elevated Ki-67, and other genetic lesions. The poor outcomes for patients with TP53-mutated mantle cell lymphoma receiving chemoimmunotherapy and second-line Bruton tyrosine kinase inhibitors represent an urgent need for alternative approaches. In this Review, we synthesise the available data to inform the management of this high-risk subset of patients and present a treatment strategy prioritising clinical trials and early use of cellular therapies.

Pevonedistat, a Nedd8-activating enzyme inhibitor, in combination with ibrutinib in patients with relapsed/refractory B-cell non-Hodgkin lymphoma

Pevonedistat (TAK924) is a Nedd8-activating enzyme inhibitor with preclinical activity in non-Hodgkin lymphoma (NHL). This open-label, Phase I, multicenter, investigator-sponsored study enrolled patients with relapsed/refractory (R/R) NHL and chronic lymphocytic leukemia (CLL). The primary objective was safety. Pevonedistat was given intravenously on days 1, 3, 5 of a 21-day cycle for 8 cycles at five dose levels (15 to 50 mg/m2); ibrutinib was administered at 420 or 560 mg orally daily continuously. Eighteen patients with NHL were enrolled, including 8 patients with mantle cell lymphoma (MCL) and 4 patients with CLL. One dose-limiting toxicity (mediastinal hemorrhage) occurred at 50 mg/m2 of pevonedistat which is the estimated maximum tolerated dose. Bruising and diarrhea were the most common adverse events (56% and 44%). Atrial fibrillation occurred in 3 patients (17%). Grade ≥3 toxicities included arthralgia, atrial fibrillation, bone pain, diarrhea, hypertension, and mediastinal hemorrhage (one patient each). The overall response rate (ORR) was 65% (100% ORR in MCL). Pevonedistat disposition was not modified by ibrutinib. scRNA-Seq analysis showed that pevonedistat downregulated NFκB signaling in malignant B-cells in vivo. Thus, pevonedistat combined with ibrutinib demonstrated safety and promising early efficacy in NHL and CLL. NAE inhibition downregulated NFκB signaling in vivo.

Resistance to Bruton tyrosine kinase inhibition in chronic lymphocytic leukaemia and non-Hodgkin lymphoma

Bruton tyrosine kinase inhibitors (BTKi) have transformed the therapeutic landscape of chronic lymphocytic leukaemia (CLL) and non-Hodgkin lymphoma. However, primary and acquired resistance to BTKi can be seen due to a variety of mechanisms including tumour intrinsic and extrinsic mechanisms such as gene mutations, activation of bypass signalling pathways and tumour microenvironment. Herein, we provide an updated review of the key clinical data of BTKi treatment in CLL, mantle cell lymphoma, and diffuse large B-cell lymphoma (DLBCL). We incorporate the most recent findings regarding mechanisms of resistance to covalent and non-covalent inhibitors, including ibrutinib, acalabrutinib, zanubrutinib and pirtobrutinib. We also cover the clinical sensitivity of certain molecular subtypes of DLBCL to an ibrutinib-containing regimen. Lastly, we summarise ongoing clinical investigations aimed at overcoming resistance via use of BTKi-containing combined therapies or the novel non-covalent BTKi. The review article targets an audience of clinical practitioners, clinical investigators and translational researchers.

CD52 and OXPHOS-potential targets in ibrutinib-treated mantle cell lymphoma

Altered features of tumor cells acquired across therapy can result in the survival of treatment-resistant clones that may cause minimal residual disease (MRD). Despite the efficacy of ibrutinib in treating relapsed/refractory mantle cell lymphoma, the obstacle of residual cells contributes to relapses of this mature B-cell neoplasm, and the disease remains incurable. RNA-seq analysis of an ibrutinib-sensitive mantle cell lymphoma cell line following ibrutinib incubation of up to 4 d, corroborated our previously postulated resistance mechanism of a metabolic switch to reliance on oxidative phosphorylation (OXPHOS) in surviving cells. Besides, we had shown that treatment-persisting cells were characterized by increased CD52 expression. Therefore, we hypothesized that combining ibrutinib with another agent targeting these potential escape mechanisms could minimize the risk of survival of ibrutinib-resistant cells. Concomitant use of ibrutinib with OXPHOS-inhibitor IACS-010759 increased toxicity compared to ibrutinib alone. Targeting CD52 was even more efficient, as addition of CD52 mAb in combination with human serum following ibrutinib pretreatment led to rapid complement-dependent-cytotoxicity in an ibrutinib-sensitive cell line. In primary mantle cell lymphoma cells, a higher toxic effect with CD52 mAb was obtained, when cells were pretreated with ibrutinib, but only in an ibrutinib-sensitive cohort. Given the challenge of treating multi-resistant mantle cell lymphoma patients, this work highlights the potential use of anti-CD52 therapy as consolidation after ibrutinib treatment in patients who responded to the BTK inhibitor to achieve MRD negativity and prolong progression-free survival.

What is the role of up-front autologous stem cell transplantation in mantle cell lymphoma?

Up-front autologous stem cell transplantation (ASCT) is the established standard of care for younger, transplant-eligible MCL patients and is associated with a prolonged progression-free survival (PFS) benefit. However, there is no randomized controlled trial data, with therapy including rituximab and cytarabine, that has established a PFS and overall survival (OS) benefit with ASCT in the modern era. Multiple retrospective studies have failed to identify an OS benefit associated with ASCT in younger MCL patients. The high-risk patient subgroup with evidence of baseline TP53 mutation has a dismal outcome with intensive chemoimmunotherapy followed by ASCT, thus up-front ASCT is not optimal for this patient subset. Ongoing randomized clinical trials will help to clarify the role of up-front ASCT in the future. For example, the ongoing European MCL Network Triangle study incorporating ibrutinib into chemoimmunotherapy induction and maintenance with and without ASCT will help define the role of ASCT in the era of novel biologically targeted agents (ClinicalTrials.gov identifier: NCT02858258). Additionally, minimal residual disease (MRD) assessment is a powerful prognostic tool in MCL, and the ongoing Eastern Cooperative Oncology Group-American College of Radiology Imaging Network E4151 study is comparing maintenance rituximab alone vs ASCT consolidation in MCL patients who achieve remission and MRD-undetectable status post induction (ClinicalTrials.gov identifier: NCT03267433). ASCT remains a highly efficacious initial therapy for younger MCL patients; however, ultimately the decision to pursue ASCT requires discussion of risks vs benefits, incorporating patient preferences and values.

The IL32/BAFF axis supports prosurvival dialogs in the lymphoma ecosystem and is disrupted by NIK inhibition

Aggressive B-cell malignancies, such as mantle cell lymphoma (MCL), are microenvironment-dependent tumors and a better understanding of the dialogs occurring in lymphoma-protective ecosystems will provide new perspectives to increase treatment efficiency. To identify novel molecular regulations, we performed a transcriptomic analysis based on the comparison of circulating MCL cells (n=77) versus MCL lymph nodes (n=107) together with RNA sequencing of malignant (n=8) versus normal B-cell (n=6) samples. This integrated analysis led to the discovery of microenvironment-dependent and tumor-specific secretion of interleukin-32 beta (IL32β), whose expression was confirmed in situ within MCL lymph nodes by multiplex immunohistochemistry. Using ex vivo models of primary MCL cells (n=23), we demonstrated that, through the secretion of IL32β, the tumor was able to polarize monocytes into specific MCL-associated macrophages, which in turn favor tumor survival. We highlighted that while IL32β-stimulated macrophages secreted several protumoral factors, they supported tumor survival through a soluble dialog, mostly driven by BAFF. Finally, we demonstrated the efficacy of selective NIK/alternative-NFkB inhibition to counteract microenvironment-dependent induction of IL32β and BAFF-dependent survival of MCL cells. These data uncovered the IL32β/BAFF axis as a previously undescribed pathway involved in lymphoma-associated macrophage polarization and tumor survival, which could be counteracted through selective NIK inhibition.

Ibrutinib as monotherapy versus combination therapy in Chinese patients with relapsed/refractory mantle cell lymphoma: A multicenter study

BACKGROUND

Ibrutinib has revolutionized the treatment of mantle cell lymphoma (MCL). Both ibrutinib monotherapy and ibrutinib-based combination therapy are important salvage options for patients with relapsed/refractory (R/R) MCL. The real-world efficacy and safety profile of the two strategies in Chinese patients with R/R MCL remain unclarified.

METHODS

In the present study, data of 121 R/R MCL patients who received either ibrutinib monotherapy (N = 68) or ibrutinib combination therapy (N = 53) in 13 medical centers in China were retrospectively reviewed.

RESULTS

With a median follow-up of 20.5 months, the overall response rate was 60.3% versus 84.9% (p = 0.003), complete remission rate was 16.2% versus 43.4% (p < 0.001), and median progression-free survival (PFS) was 18.5 months (95% confidence interval [CI], 12.1-21.8) vs. 30.8 months (95% CI, 23.5-NR) (hazard ratio, 0.53 [95% CI, 0.30-0.93]; p = 0.025), with ibrutinib monotherapy and ibrutinib-based combination therapy, respectively. Subgroup analysis showed that patients with male gender, no refractory disease, Ki67 <30%, previous line of therapy = 1, non-blastoid subtype, and the number of extranodal sites involved <2 might benefits more from the combination therapy. Treatment-emergent adverse events were similar, except for a higher incidence of all grade neutropenia in the ibrutinib combination group (12.7% vs. 32.0%, p = 0.017).

CONCLUSIONS

Ibrutinib combination therapy demonstrated potentially superior efficacy and comparable tolerability to ibrutinib monotherapy. Ibrutinib-based combination therapy could be one of the prominent treatment options for R/R MCL patients.

BTK inhibitors in the treatment of hematological malignancies and inflammatory diseases: mechanisms and clinical studies

Bruton's tyrosine kinase (BTK) is an essential component of multiple signaling pathways that regulate B cell and myeloid cell proliferation, survival, and functions, making it a promising therapeutic target for various B cell malignancies and inflammatory diseases. Five small molecule inhibitors have shown remarkable efficacy and have been approved to treat different types of hematological cancers, including ibrutinib, acalabrutinib, zanubrutinib, tirabrutinib, and orelabrutinib. The first-in-class agent, ibrutinib, has created a new era of chemotherapy-free treatment of B cell malignancies. Ibrutinib is so popular and became the fourth top-selling cancer drug worldwide in 2021. To reduce the off-target effects and overcome the acquired resistance of ibrutinib, significant efforts have been made in developing highly selective second- and third-generation BTK inhibitors and various combination approaches. Over the past few years, BTK inhibitors have also been repurposed for the treatment of inflammatory diseases. Promising data have been obtained from preclinical and early-phase clinical studies. In this review, we summarized current progress in applying BTK inhibitors in the treatment of hematological malignancies and inflammatory disorders, highlighting available results from clinical studies.

The NF-κB Pharmacopeia: Novel Strategies to Subdue an Intractable Target

NF-κB transcription factors are major drivers of tumor initiation and progression. NF-κB signaling is constitutively activated by genetic alterations or environmental signals in many human cancers, where it contributes to almost all hallmarks of malignancy, including sustained proliferation, cell death resistance, tumor-promoting inflammation, metabolic reprogramming, tissue invasion, angiogenesis, and metastasis. As such, the NF-κB pathway is an attractive therapeutic target in a broad range of human cancers, as well as in numerous non-malignant diseases. Currently, however, there is no clinically useful NF-κB inhibitor to treat oncological patients, owing to the preclusive, on-target toxicities of systemic NF-κB blockade. In this review, we discuss the principal and most promising strategies being developed to circumvent the inherent limitations of conventional IκB kinase (IKK)/NF-κB-targeting drugs, focusing on new molecules that target upstream regulators or downstream effectors of oncogenic NF-κB signaling, as well as agents targeting individual NF-κB subunits.

Tipping the balance: toward rational combination therapies to overcome venetoclax resistance in mantle cell lymphoma

Mantle cell lymphoma (MCL), an aggressive, but incurable B-cell lymphoma, is genetically characterized by the t(11;14) translocation, resulting in the overexpression of Cyclin D1. In addition, deregulation of the B-cell lymphoma-2 (BCL-2) family proteins BCL-2, B-cell lymphoma-extra large (BCL-XL), and myeloid cell leukemia-1 (MCL-1) is highly common in MCL. This renders these BCL-2 family members attractive targets for therapy; indeed, the BCL-2 inhibitor venetoclax (ABT-199), which already received FDA approval for the treatment of chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML), shows promising results in early clinical trials for MCL. However, a significant subset of patients show primary resistance or will develop resistance upon prolonged treatment. Here, we describe the underlying mechanisms of venetoclax resistance in MCL, such as upregulation of BCL-XL or MCL-1, and the recent (clinical) progress in the development of inhibitors for these BCL-2 family members, followed by the transcriptional and (post-)translational (dys)regulation of the BCL-2 family proteins, including the role of the lymphoid organ microenvironment. Based upon these insights, we discuss how rational combinations of venetoclax with other therapies can be exploited to prevent or overcome venetoclax resistance and improve MCL patient outcome.

Clinicopathologic Features and Treatment of CD10-Positive Mantle Cell Lymphoma: A Case Report and Review of Literature

Mantle cell lymphoma (MCL) is a rare and aggressive non-Hodgkin’s B cell lymphoma characterized by the translocation t(11;14) (q13;32) and overexpression of CCND1. MCL is immunophenotypically identified as CD20⁺, CD5⁺, CyclinD1+, CD43⁺, CD10⁻, BCL6⁻, and CD23⁻. It is often distinguished from B cell lymphomas of germinal center cell origin by the absence of CD10 expression. Here we report the unique clinicopathologic features of a patient with CD10⁺ MCL with gastrointestinal involvement and review current literature identifying this unique immunophenotype.

Obinutuzumab in the treatment of B-cell malignancies: a comprehensive review

The type II anti-CD20 antibody obinutuzumab has structural and mechanistic features that distinguish it from the first anti-CD20 antibody, rituximab, which have translated into improved efficacy in phase III trials in indolent non-Hodgkin lymphoma and chronic lymphocytic leukemia (CLL). These gains have been shown through improvements in, and/or increased durability of, tumor response, and increases in progression-free survival in patients with CLL or follicular lymphoma (FL). Ongoing research is focusing on the use of biomarkers and the development of chemotherapy-free regimens involving obinutuzumab. phase II trials of such treatment regimens have shown promise for CLL, FL and mantle cell lymphoma, while phase III trials have highlighted obinutuzumab as the antibody partner of choice for novel agents in first-line CLL treatment.

SOHO State of the Art Updates and Next Questions: Targeted therapies and emerging novel treatment approaches for Waldenström Macroglobulinemia

Waldenström Macroglobulinemia (WM) is a rare hematologic malignancy characterized by the presence of lymphoplasmacytic lymphoma cells involving the bone marrow and production of a monoclonal IgM paraprotein. Recurrent somatic mutations in MYD88^L265P and CXCR4 have been reported in 90% to 95% and 30% to 40% of patients with WM, respectively. Standard treatment regimens combine the anti-CD20 antibody rituximab with alkylating agents (eg, bendamustine, cyclophosphamide), nucleoside analogs (eg, fludarabine, cladribine), or proteasome inhibitors (eg, bortezomib, carfilzomib, and ixazomib). Covalent BTK inhibitors (eg, ibrutinib, acalabrutinib, zanubrutinib) have shown to be safe and highly effective in patients with WM. Novel and promising agents in this disease include next-generation covalent BTK inhibitors (eg, tirabrutinib, orelabrutinib), non-covalent BTK inhibitors (eg, pirtobrutinib, ARQ531), BCL-2 antagonists (eg, venetoclax), and CXCR4-targeted agents (eg, mavorixafor, ulocuplumab), among others. Future studies will focus on developing fixed-duration combinations regimens with these novel agents aimed at increasing durable responses while minimizing toxicity and cost.

SOHO State of the Art Updates and Next Questions: Managing Relapsed Mantle Cell Lymphoma

Mantle cell lymphoma (MCL) is a rare subtype of B-cell non-Hodgkin lymphoma i.e., incurable with current therapies. While some patients experience prolonged remissions following initial therapy, most will have a relapsing-remitting course requiring several lines of treatment over the course of their disease. Several targeted therapies are now available to treat patients with relapsed MCL. The Bruton's tyrosine kinase (BTK) inhibitors, including ibrutinib, acalabrutinib, and zanubrutinib, are highly active in MCL and currently approved for treating patients with relapsed disease. Bortezomib and lenalidomide are available as monotherapy or in combination with other agents. Venetoclax is active and can be considered for use in relapsed MCL, although it is not currently approved by regulatory agencies. Chimeric antigen receptor T-cell (CAR-T) therapy with brexucabtagene autoleucel yields high response rates and is now approved for patients with relapsed MCL. Allogeneic stem cell transplant remains an option for a small subset of medically fit and motivated patients who have progressed through multiple lines of therapy, although its use is limited by substantial toxicity. There is currently no standard approach to sequencing therapies for patients with relapsed MCL, and the ability to utilize disease biologic and clinical characteristics to guide treatment decisions in this setting remains limited. In this review, we summarize the current evidence to guide the management of patients with relapsed MCL, review emerging agents and combination therapies that are under investigation, and outline our current treatment approach for these patients.

Chidamide and venetoclax synergistically exert cytotoxicity on multiple myeloma by upregulating BIM expression

Background

Multiple myeloma (MM) is the second most common hematologic malignancy with almost all patients eventually having relapse or refractory MM (RRMM), thus novel drugs or combination therapies are needed for improved prognosis. Chidamide and venetoclax, which target histone deacetylase and BCL2, respectively, are two promising agents for the treatment of RRMM.

Results

Herein, we found that chidamide and venetoclax synergistically exert an anti-myeloma effect in vitro in human myeloma cell lines (HMCLs) with a combination index (CI) < 1. Moreover, the synergistic anti-myeloma effect of these two drugs was demonstrated in primary MM cells and MM xenograft mice. Mechanistically, co-exposure to chidamide and venetoclax led to cell cycle arrest at G0/G1 and a sharp increase in DNA double-strand breaks. In addition, the combination of chidamide and venetoclax resulted in BCL-X_L downregulation and BIM upregulation, and the latter protein was proved to play a critical role in sensitizing HMCLs to co-treatment.

Conclusion

In conclusion, these results proved the high therapeutic potential of venetoclax and chidamide combination in curing MM, representing a potent and alternative salvage therapy for the treatment of RRMM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-022-01306-7.