MAJIC: a phase III trial of acalabrutinib + venetoclax versus venetoclax + obinutuzumab in previously untreated chronic lymphocytic leukemia or small lymphocytic lymphoma

Targeting the Immune Microenvironment in Chronic Lymphocytic Leukemia: An Evolving Therapeutic Strategy

Although small molecule inhibitors that target the aberrant signaling pathways and molecular defects of chronic lymphocytic leukemia (CLL) result in improved survival benefits vs. traditional chemoimmunotherapy or chemotherapy, treatment resistance may result later, reflecting the intrinsic tumor heterogeneity, persistence of the leukemic clone, and presence of the tumor microenvironment, which supports the survival of the disease clone. Patients with CLL have immune-related abnormalities in T lymphocyte subset composition, immune synapse formation, and other immune dysregulations. Cellular interactions between the disease clone and its microenvironment provide therapeutic opportunities to target these tumor pathogenesis pathways, potentially improving the patient's immune functions and clinical outcomes of targeted therapies. At present, despite the lack of response of immune checkpoint inhibitors in CLL, they showed promising efficacy in patients with Richter transformation. Together with CD19-targeted chimeric antigen receptor-modified T cell (CAR-T) therapy, novel bispecific antibodies and other immunotherapies are being investigated to improve survival outcomes for patients with relapsed or refractory (R/R) CLL, as exemplified by epcoritamab, a bispecific antibody that recently demonstrated initial efficacy in R/R CLL and in patients in high-risk CLL subgroups, including those with TP53 aberrations and unmutated genes that encode immunoglobulin variable heavy chain region (IGHV). Furthermore, to address the immune escape of cancer cells and issues that impact the durability of single-targeted T cell-redirected therapies, novel strategies such as trispecific antibodies and combination therapies are being investigated to increase tumor specificity or immune cell activation. In summary, there is emerging evidence that immunotherapies may counteract the immunosuppressive microenvironment of CLL, improve clinical responses, decrease the risk of infection, and overcome treatment resistance.

When and How Long to Treat Chronic Lymphocytic Leukemia?

Chronic lymphocytic leukemia (CLL) remains an incurable disease, except in rare cases treated with allogeneic stem-cell transplantation or favorable-risk CLL treated with chemoimmunotherapy. Treatment initiation follows the Rai and Binet staging systems, but the International Workshop on Chronic Lymphocytic Leukemia criteria emphasize active disease rather than stage alone. Early treatment in asymptomatic, high-risk patients has not shown an overall survival benefit, even with targeted therapies such as Bruton's tyrosine kinase and BCL2 inhibitors. The watch-and-wait strategy remains standard, although future trials may refine early treatment indications for specific high-risk groups.

The Impact of Minimal Residual Disease Measurement in the Management of Chronic Lymphocytic Leukemia

Background: The treatment of chronic lymphocytic leukemia (CLL) has advanced considerably in recent years. Bruton's tyrosine kinase inhibitors (BTKis) and B-cell lymphoma 2 inhibitors (BCL2is) such as venetoclax have largely supplanted chemoimmunotherapy for both frontline and relapsed CLL. With the introduction of additional innovative agents and regimens, the clinical role of measurable residual disease (MRD) has become complicated. Methods: In this article, we will review the existing literature on MRD and its utility in the management of CLL. We will review the definitions of MRD, review MRD detection methods, and discuss the use of MRD in the current CLL treatment landscape. In doing so, we will clarify the present and conceivable future roles of MRD for the treatment of CLL. Conclusions: MRD is a powerful tool to assess response to CLL therapies, and can be prognostic with certain treatment regimens, such as fixed-duration venetoclax-based treatment. While we do not recommend MRD testing in routine clinical practice, we believe it has an important role in assessing treatment response and will be utilized routinely in the future. Further studies to incorporate MRD into treatment strategies for CLL are ongoing and will help to inform how we utilize it in clinical practice.

Prognostic and predictive impact of NOTCH1 mutation in chronic lymphocytic leukemia: a systematic review

Mutations in the NOTCH1 oncogene are recurrently linked to chronic lymphocytic leukemia (CLL), found in approximately 10% of CLL cases at diagnosis. Although these mutations are associated with clinical outcomes, their significance in the context of treatment with anti-CD20 monoclonal antibodies, Bruton's tyrosine kinase inhibitors, and BCL2 inhibitors remains controversial. Consequently, testing for NOTCH1 mutations is not recommended outside of a clinical setting. This systematic literature review aims to consolidate the current understanding that NOTCH1 mutations are exploratory and not recommended for routine clinical practice.

Phase II Study of Acalabrutinib, Venetoclax, and Obinutuzumab in a Treatment-Naïve Chronic Lymphocytic Leukemia Population Enriched for High-Risk Disease

PURPOSE

The AMPLIFY trial recently established fixed-duration acalabrutinib, venetoclax, and obinutuzumab (AVO) as a new standard-of-care option for patients with previously untreated chronic lymphocytic leukemia (CLL) with wild-type TP53; however, due to the chemoimmunotherapy control arm, AMPLIFY excluded patients with high-risk TP53 aberration, for whom current standards of care are continuous Bruton tyrosine kinase inhibitor therapy or alternatively fixed-duration venetoclax-based doublets. AVO has not previously been evaluated in patients with CLL with TP53 aberration.

METHODS

This investigator-sponsored, multicenter, phase II study enrolled patients with treatment-naïve CLL enriched for high-risk CLL, defined by TP53 aberration (ClinicalTrials.gov identifier: NCT03580928). Patients received acalabrutinib, obinutuzumab, and then venetoclax, with each treatment introduced sequentially and in combination, with the duration guided by measurable residual disease (MRD). Patients who achieved undetectable MRD (uMRD) after either 15 or 24 cycles could discontinue treatment. The primary end point was complete remission (CR) with bone marrow uMRD (BM-uMRD) at the start of cycle 16.

RESULTS

Seventy-two patients were accrued, including 45 patients with TP53 aberration. The CR with BM-uMRD rates at the start of cycle 16 were 42% in patients with TP53 aberration and 42% in all-comers, and the BM-uMRD rates were 71% and 78%, respectively. Hematologic toxicities were mainly low grade, and cardiovascular toxicities and bleeding complications were infrequent. After a median follow-up of 55.2 months, 10 patients had progressed, including four with transformation, and three patients died. Four-year progression-free survival and overall survival for patients with or without TP53 aberration were 70%/96% and 88%/100%, respectively.

CONCLUSION

AVO was highly active and well tolerated in patients with previously untreated high-risk CLL, supporting its use as a new standard-of-care treatment option.

Targeting Tumor Microenvironment Interactions in Chronic Lymphocytic Leukemia Using Leukotriene Inhibitors

Chronic lymphocytic leukemia (CLL) cells depend on microenvironment niches for proliferation and survival. The adhesion of tumor cells to stromal cells in such niches triggers the activation of signaling pathways crucial for their survival, including B-cell receptor (BCR) signaling. While inhibitors of Bruton's tyrosine kinase (BTKi) have shown efficacy in patients with CLL by disrupting these interactions, acquired resistance and toxicity remain a challenge during long-term therapy. Thus, identifying additional therapeutic modalities is important. Previously, we demonstrated that 5-lipoxygenase (5-LOX) pathway inhibitors reduced mantle cell lymphoma (MCL) cell adhesion to stromal cells, motivating us to investigate their potential in the context of CLL. We employed an ex vivo co-culture model to study CLL cell adhesion to stromal cells in the absence and presence of 5-LOX pathway inhibitors (zileuton and MK886) as well as the BTKi ibrutinib that was included for comparative purposes. Our findings demonstrated that different CLL samples adhere to stromal cells differentially. We observed a variable decrease in CLL cell adhesion to stromal cells following the inhibition of the 5-LOX pathway across a spectrum of patient samples that was distinct to the spectrum for ibrutinib. Positive and negative correlations were shown between the clinical and genetic features of the CLL samples and their level of adherence to stromal cells in both the absence and presence of the tested inhibitors. These results suggest the 5-LOX pathway as a candidate for assessment as a new therapeutic target in CLL.

Measurable residual disease-driven treatment in first-line chronic lymphocytic leukaemia

The therapeutic paradigm for patients suffering from chronic lymphocytic leukaemia continues to rapidly evolve. Fixed duration therapies continue to develop using novel-novel non-chemotherapeutic combinations. B-cell lymphoma 2 (BCL2) inhibitors in combination with either anti-CD20 antibody or Bruton tyrosine kinase inhibitors are able to achieve deep responses. Levels of attained 'negative' measurable residual disease (MRD, also known as minimal residual disease) have been shown to predict survival outcomes in a number of settings, including following immunochemotherapy and BCL2-combinations. This review will outline the current data supporting fixed duration treatment approaches, the use of MRD in clinical practice, alongside the challenges and possibilities for MRD utility in the future.

Venetoclax-obinutuzumab for previously untreated chronic lymphocytic leukemia: 6-year results of the randomized phase 3 CLL14 study

ABSTRACT

In the CLL14 study, patients with previously untreated chronic lymphocytic leukemia (CLL) and coexisting conditions were randomized to 12 cycles of venetoclax-obinutuzumab (Ven-Obi, n = 216) or chlorambucil-obinutuzumab (Clb-Obi, n = 216). Progression-free survival (PFS) was the primary end point. Key secondary end points included time-to-next-treatment (TTNT), rates of undetectable minimal residual disease (uMRD), overall survival (OS), and rates of adverse events. Patient reported outcomes of time until definitive deterioration (TUDD) in quality of life (QoL) were analyzed. At a median observation time of 76.4 months, PFS remained superior for Ven-Obi compared with Clb-Obi (median, 76.2 vs 36.4 months; hazard ratio [HR], 0.40; 95% confidence interval [CI], 0.31-0.52; P < .0001). Likewise, TTNT was longer after Ven-Obi (6-year TTNT, 65.2% vs 37.1%; HR, 0.44; 95% CI, 0.33-0.58; P < .0001). In the Ven-Obi arm, presence of del(17p), unmutated immunoglobulin heavy-chain variable region, and lymph node size of ≥5 cm were independent prognostic factors for shorter PFS. The 6-year OS rate was 78.7% in the Ven-Obi and 69.2% in the Clb-Obi arm (HR, 0.69; 95% CI, 0.48-1.01; P = .052). A significantly longer TUDD in global health status/QoL was observed in the Ven-Obi than in the Clb-Obi arm (median, 82.1 vs 65.1 months; HR, 0.70; 95% CI, 0.51-0.97). Follow-up-adjusted second primary malignancies incidence rates were 2.3 and 1.4 per 1000 patient-months in the Ven-Obi and Clb-Obi arm, respectively. The sustained long-term survival and QoL benefits support the use of 1-year fixed-duration Ven-Obi in CLL. This trial was registered at www.ClinicalTrials.gov as #NCT02242942.

Mitigating time toxicity in lymphoma and multiple myeloma

The concept of time toxicity in oncology refers to the presence of frequent healthcare-related interactions that can interfere with patient well-being. In this review, we examine several manifestations of time toxicity in non-Hodgkin lymphoma and multiple myeloma and discuss their impact on decision-making with patients. For example, time toxicity may influence the choice of chemoimmunotherapy versus lenalidomide-rituximab in follicular lymphoma. In myeloma, it may inform the optimal dosing schedule for proteasome inhibitors and bisphosphonates. In both malignancies, varying time toxicity profiles are a key distinction between chimeric antigen receptor T-cell therapies and bispecific antibodies. We outline the challenges with measuring time toxicity as a trial endpoint but discuss its importance as a consideration for patient care, both in standard-of-care settings and in clinical trials. Throughout the review, we highlight strategies to lower the time toxicity of therapies in lymphoma and myeloma without compromising their efficacy or patient safety.

Monitoring Response and Resistance to Treatment in Chronic Lymphocytic Leukemia

The recent evolution in chronic lymphocytic leukemia (CLL) targeted therapies led to a progressive change in the way clinicians manage the goals of treatment and evaluate the response to treatment in respect to the paradigm of the chemoimmunotherapy era. Continuous therapies with BTK inhibitors achieve prolonged and sustained control of the disease. On the other hand, venetoclax and anti-CD20 monoclonal antibodies or, more recently, ibrutinib plus venetoclax combinations, given for a fixed duration, achieve undetectable measurable residual disease (uMRD) in the vast majority of patients. On these grounds, a time-limited MRD-driven strategy, a previously unexplored scenario in CLL, is being attempted. On the other side of the spectrum, novel genetic and non-genetic mechanisms of resistance to targeted treatments are emerging. Here we review the response assessment criteria, the evolution and clinical application of MRD analysis and the mechanisms of resistance according to the novel treatment strategies within clinical trials. The extent to which this novel evidence will translate in the real-life management of CLL patients remains an open issue to be addressed.

Metabolic and toxicological considerations of Bruton's tyrosine kinase inhibitors for the treatment of chronic lymphocytic leukemia/small lymphocytic lymphoma

INTRODUCTION

Bruton tyrosine kinase inhibitors (BTKi) have been used for the management of human diseases since the approval of the first-in class agent, ibrutinib, by the Food and Drug Administration in 2013 for the treatment of patients with mantle cell lymphoma (MCL). Ibrutinib is a covalent inhibitor along with second-class BTKis: acalabrutinib and zanubrutinib. These well-tolerated agents have transformed the treatment landscape of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). A new class of these inhibitors, non-covalent, might become an answer to the emerging resistance by avoiding the sustained contact with the kinase binding domain.

AREAS COVERED

This article examines the chemical composition, mechanism of action, metabolic characteristics, and potential toxicity of inhibitors targeting Bruton tyrosine kinase. A comprehensive search was conducted across English-language articles in PubMed, Web of Science, and Google Scholar.

EXPERT OPINION

Bruton tyrosine kinase inhibitors have greatly enhanced the armamentarium against lymphoid malignancies including CLL/SLL. Their future lies in the choice of appropriate patients who will benefit from the treatment without significant adverse reaction. Combination chemotherapy-free fixed-duration regimens with targeted molecules will allow for MRD-driven approach in patients with CLL/SLL in the near future.

Frontline Therapy of CLL-Changing Treatment Paradigms

PURPOSE OF REVIEW

The therapeutic landscape for chronic lymphocytic leukemia (CLL) has undergone a complete makeover following the introduction of highly effective targeted therapies, beginning with ibrutinib which first attained regulatory approval for CLL in 2014.

RECENT FINDINGS

In recent years, we have seen further refinement of therapeutic options with the development of newer-generation Bruton's tyrosine kinase inhibitors (BTKi) including acalabrutinib and zanubrutinib that improve upon the safety of ibrutinib. Additionally, venetoclax-based approaches, combined with anti-CD20 antibodies, have allowed for time-limited targeted therapeutic strategies which are particularly attractive for certain subsets of patients though have demonstrated efficacy across all subgroups. Lastly, there is an ongoing movement toward the development of time-limited strategies inclusive of both a BTKi and venetoclax that may further widen potential options. CLL patients requiring frontline therapy have a unique burden of choice between highly effective therapies that differ substantially with respect to side effect profiles and schedules. This review will focus on the frontline management of CLL in the setting of these rapidly changing options.

Targeting the NTSR2/TrkB oncogenic pathway in chronic lymphocytic leukemia

Current therapies that target the B-cell receptor pathway or the inhibition of anti-apoptotic proteins do not prevent the progressive forms of chronic lymphocytic leukemia (CLL), have low long-term efficacy and are subject to therapeutic resistance. Deciphering the mechanisms of leukemic cell survival and searching for new specific targets therefore remain major challenges to improve the management of this disease. It was evidenced that NTSR2 (neurotensin receptor 2), through the recruitment of TRKB (tropomyosin related kinase B), induces survival pathways in leukemic B cells. We have investigated the therapeutic potential of this protein complex as a new target. The binding domain of NTSR2 and TRKB was identified and a peptide targeting the latter was designed. The peptide binds TRKB and efficiently decreases the interaction of the two proteins. It is also effectively internalized by CLL-B cells in which it notably affects Src family kinase signaling and anti-apoptotic proteins levels. It demonstrated a cytotoxic effect both in vitro on the MEC-1 cell line and ex vivo on a cohort of 30 CLL patients. Altogether, these results underline the therapeutic potential of the NTSR2/TRKB protein complex as a target in CLL and open new perspectives for the development of targeted therapies.

Chronic Lymphocytic Leukemia: Time-Limited Therapy in the First-Line Setting and Role of Minimal Residual Disease

PURPOSE OF REVIEW

In this review, we provide an overview of different time-limited combination therapies of chronic lymphocytic leukemia (CLL) and summarize the data of pivotal clinical studies. Furthermore, we discuss the relevance of MRD in clinical trials and summarize the challenges that arise in routine clinical care. Finally, we provide an outlook on studies and datasets needed to optimize the use of time-limited treatment strategies and MRD assessments in modern CLL management.

RECENT FINDINGS

In recent years, first-line treatment of CLL has undergone a considerable transformation, with targeted substances having largely replaced chemoimmunotherapy (CIT) as a time-limited strategy in the frontline setting. BTK inhibitors were the first class of targeted agents introduced in CLL, which achieved longer progression-free survival (PFS) and in some cases also overall survival (OS) than CIT. However, this required an indefinite drug intake until disease progression, while CIT is generally administered over the course of few months. In contrast to BTK inhibitors, BCL2 inhibitors, another class of targeted agents, can achieve high rates of undetectable minimal residual disease (uMRD) levels and induce deep molecular remissions with the potential to stop treatment while maintaining remissions. Combinations of BCL2 inhibitors with CD20 antibodies or with BTK inhibitors have been explored to establish time-limited treatment strategies with targeted agents. In this context, one of the strongest predictors of long-term outcomes is MRD status at the end of treatment, which has been shown to correlate closely with PFS and OS in most cases.

Treatment of Chronic Lymphocytic Leukemia in the Personalized Medicine Era

Chronic lymphocytic leukemia is a lymphoproliferative disorder marked by the expansion of monoclonal, mature CD5+CD23+ B cells in peripheral blood, secondary lymphoid tissues, and bone marrow. The disease exhibits significant heterogeneity, with numerous somatic genetic alterations identified in the neoplastic clone, notably mutated TP53 and immunoglobulin heavy chain mutational statuses. Recent studies emphasize the pivotal roles of genetics and patient fragility in treatment decisions. This complexity underscores the need for a personalized approach, tailoring interventions to individual genetic profiles for heightened efficacy. The era of personalized treatment in CLL signifies a transformative shift, holding the potential for improved outcomes in the conquest of this intricate hematologic disorder. This review plays a role in elucidating the evolving CLL treatment landscape, encompassing all reported genetic factors. Through a comprehensive historical analysis, it provides insights into the evolution of CLL management. Beyond its retrospective nature, this review could be a valuable resource for clinicians, researchers, and stakeholders, offering a window into the latest advancements. In essence, it serves as a dynamic exploration of our current position and the promising prospects on the horizon.

SOHO State of the Art Updates and Next Questions: Updates on BTK Inhibitors for the Treatment of Chronic Lymphocytic Leukemia

Over the last decade, targeted inhibition of Bruton's tyrosine kinase (BTK) has led to a paradigm shift in the way chronic lymphocytic leukemia (CLL) is managed. BTK inhibitors (BTKi) are broadly classified as covalent BTKI and noncovalent BTKi (cBTKi and ncBTK) Ibrutinib, as the first approved cBTKi, vastly improved outcomes for patients with CLL over prior chemoimmunotherapy regimens. However, long-term use is limited by both intolerance and resistance. The second generation of more selective BTKi were developed to improve tolerability. While these agents have led to an improved safety profile in comparison to Ibrutinib (both acalabrutinib and zanubrutinib), and improved efficacy (zanubrutinib), intolerance occasionally occurs, and resistance remains a challenge. The third generation of BTKi, which noncovalently or reversibly inhibits BTK, has shown promising results in early phase trials and are being evaluated in the phase 3 setting. These drugs could be an effective treatment option in patients with either resistance and intolerance to cBTKi. The most recent development in therapeutic agents targeting BTK is the development of BTK degraders. By removing BTK, as opposed to inhibiting it, these drugs could remain efficacious irrespective of BTK resistance mutations, however clinical data are limited at this time. This review summarizes the evolution and ongoing development of newer BTKi and BTK degraders in the management of CLL, with a focus of future directions in this field, including how emerging clinical data could inform therapeutic sequencing in CLL management.