ASCEND: Phase III, Randomized Trial of Acalabrutinib Versus Idelalisib Plus Rituximab or Bendamustine Plus Rituximab in Relapsed or Refractory Chronic Lymphocytic Leukemia

Immunotherapy combinations for chronic lymphocytic leukemia: advantages and disadvantages

In the last few years, BTK inhibitors, PI3K inhibitors, and venetoclax have been approved for clinical use against chronic lymphocytic leukemia (CLL), both as single agents, and in combination. This article summarizes recent achievements in the treatment of patients with CLL, and pays special attention to novel targeted drugs and monoclonal antibodies (Mabs). A literature search was conducted of the PubMed and Google Scholar databases. Rituximab and obinutuzumab have been combined with chemotherapy, and more recently, with BTK inhibitors, PI3K inhibitors, and venetoclax. These agents have demonstrated high activity in treatment naïve (TN) and relapsed or refractory (RR) CLL. Immunochemotherapy regimens are currently considered in TN younger patients with IGHV-mutated disease and should not be given in patients without IGHV mutation. BTK inhibitors are more commonly used as monotherapy in TN and RR patients. PI3K inhibitors can be combined with CD20 Mabs, but their use in CLL is limited due to safety concerns. Venetoclax is typically combined with anti-CD20 Mabs in CLL. Generally, the optimal sequencing of therapies remains to be established, and the selection of upfront therapy needs to be tailored to the individual patient.

PI3k Inhibitors in NHL and CLL: An Unfulfilled Promise

Phosphatidylinositol 3-kinases (PI3Ks) are a family of intracellular signal transducer enzymes that can attach a phosphate group to the 3'-hydroxyl of the inositol moiety of membrane-embedded phosphatidylinositol (PI). PI3Ks have been shown to play important roles in cell proliferation, growth, survival, motility, and metabolism. Nonetheless, the PI3K pathway has also shown to be overactivated in several tumors, particularly B-cell malignancies. In recent years, the PI3K signaling pathway has become the major focus of substantial drug discovery and development efforts. Selective (PI3K) inhibitors have been approved for the treatment of chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL), and indolent non-Hodgkin lymphomas (iNHL), such as follicular lymphoma and marginal-zone lymphoma. Four selective PI3K inhibitors have received accelerated FDA approvals for the treatment of patients with relapsed/refractory (R/R) CLL and/or iNHL based mainly on single-arm Phase II studies: Idelalisib (PI3K-δ inhibitor), copanlisib (dual PI3K-α and PI3K-δ inhibitor), duvelisib (dual PI3K-γ and PI3K-δ inhibitor), and umbralisib (dual PI3Kδ and CK1ε inhibitor). Conversely, recent interim results of randomized control trials (RCTs) involving some of these agents, showed a worrisome trend of decrease in overall survival (OS), and an increase in fatal and severe adverse effects, in comparison with patients in the control arms. Consequently, the class of PI3K inhibitors came under scrutiny, with an FDA expert panel voting on April 21, 2022, recommending that future FDA approvals of PI3K inhibitors be supported by randomized data, rather than single-arm data only, and further discontinuing the use of almost all the PI3K inhibitors in hematologic malignancies. As we believe further research is needed to help potentialize PI3K inhibitors by improving their safety profiles, this mini-review aims at revisiting the clinical successes, the failures, and the promising aspect of this class of drugs, while presenting possible ways that could benefit its successful development.

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.

How Have Targeted Agents Changed the Treatment Landscape for Elderly Patients with CLL?

PURPOSE OF REVIEW

Chronic lymphocytic leukemia (CLL) is a common hematologic malignancy in elderly patients. At the time of diagnosis, most patients have comorbid medical conditions. Although patients have other competing medical issues, the majority of patients will die from CLL or CLL-related complications. This review will discuss treatment in elderly patients with CLL.

RECENT FINDINGS

Recent work has focused on understanding the role comorbid medical conditions play in the management of CLL in elderly patients, including the use of geriatric assessment, Charlson comorbidity index, cumulative illness rating scale, and most recently, the CLL-comorbidity index. The treatment landscape for CLL has shifted from chemoimmunotherapy to the use of targeted agents. Several clinical trials in elderly patients have demonstrated improvement in progression-free survival (PFS) with ibrutinib + / - obinutuzumab, acalabrutinib + / - obinutuzumab, zanubrutinib, venetoclax-obinutuzumab, idelalisib, and duvelisib. The adverse event profile and potential for drug-drug interactions in the treatment of CLL in elderly patients have not been described, and further studies are needed to determine optimal treatment. Treatment of elderly patients with CLL should be made on a case-by-case basis based on a patient's fitness, comorbid medical conditions, and concomitant medications. The use of targeted agents has improved outcomes in this patient population, but further studies are needed to determine the best practice.

Practical management of chronic lymphocytic leukemia with acalabrutinib

Treatment of chronic lymphocytic leukemia (CLL) has been transformed in the past two decades. The introduction of targeted therapies has improved patient outcomes and the deliverability of effective therapies. Making the best use of the next wave of Bruton's tyrosine kinase (BTK) inhibitors requires an understanding of the nuances that separate the drugs in this class of agents. This paper reviews the newer BTK inhibitors and provides practical guidance on the management of CLL using acalabrutinib. Acalabrutinib is a safe and efficacious BTKi in the treatment of CLL. While some side effects appear to be an "on-target" effect of BTK inhibition, the selectivity of second-generation covalent BTK inhibitors such as acalabrutinib may result in a favorable safety profile due to less off-target kinase inhibition. Acalabrutinib represents a well-tolerated and effective alternative to ibrutinib in the management of CLL.

Small molecule inhibitors targeting the cancers

Compared with traditional therapies, targeted therapy has merits in selectivity, efficacy, and tolerability. Small molecule inhibitors are one of the primary targeted therapies for cancer. Due to their advantages in a wide range of targets, convenient medication, and the ability to penetrate into the central nervous system, many efforts have been devoted to developing more small molecule inhibitors. To date, 88 small molecule inhibitors have been approved by the United States Food and Drug Administration to treat cancers. Despite remarkable progress, small molecule inhibitors in cancer treatment still face many obstacles, such as low response rate, short duration of response, toxicity, biomarkers, and resistance. To better promote the development of small molecule inhibitors targeting cancers, we comprehensively reviewed small molecule inhibitors involved in all the approved agents and pivotal drug candidates in clinical trials arranged by the signaling pathways and the classification of small molecule inhibitors. We discussed lessons learned from the development of these agents, the proper strategies to overcome resistance arising from different mechanisms, and combination therapies concerned with small molecule inhibitors. Through our review, we hoped to provide insights and perspectives for the research and development of small molecule inhibitors in cancer treatment.

Chronic lymphocytic leukemia treatment algorithm 2022

The treatment landscape for patients with chronic lymphocytic leukemia (CLL) has changed considerably with the introduction of very effective oral targeted therapies (such as Bruton tyrosine kinase inhibitors and venetoclax) and next-generation anti-CD20 monoclonal antibodies (such as obinutuzumab). These agents lead to improved outcomes in patients with CLL, even among those with high-risk features, such as del17p13 or TP53 mutation and unmutated immunoglobulin heavy chain (IGHV) genes. Selecting the right treatment for the right patient requires consideration of disease characteristics and prior treatment sequence, as well as patient preferences and comorbidities. The CLL-International Prognostic Index (CLL-IPI) remains the best-validated tool in predicting the time to first therapy among previously untreated patients, which guides selection for early intervention efforts. This review summarizes our current approach to the management of CLL, right from the time of diagnosis through relapsed disease.

Prognostic markers in patients with chronic lymphocytic leukaemia on targeted therapy, chemoimmunotherapy with anti-CD20 monoclonal antibody: a systematic review and meta-analysis of prognostic factors

Combination chemoimmunotherapy (CIT) consisting of anti-CD20 has improved the progression-free survival (PFS) and overall survival (OS) of patients with chronic lymphocytic leukaemia (CLL). We performed a comprehensive synthesis of prognostic factors in patients with CLL on combined CIT with anti-CD20 antibodies compared with standard chemotherapy alone or targeted therapy.We searched the MEDLINE and academic search complete electronic databases as well as clinicaltrials.gov (from inception up to 01 August 2022) for randomised controlled trials examining chemoimmunotherapy and targeted therapy in patients with CLL. The risk of bias and the quality of evidence was assessed using the quality in prognostic studies tool (QUIPS).A total of 10 prognostic factors were identified and evaluated in patients with CLL on anti-CD20 antibody-containing CIT. The predictive value of the following prognostic factors was confirmed and associated with poor patient outcomes; deletion 17p (HR = 3.39), Immunoglobulin heavy chain variable region gene mutation status (HR = 0.96) and β2-microglobulin (HR = 1.41).Conventional predictive factors may have retained prognostic value and could be useful in the stratification of patients who may be non-responsive to CIT.Trial registration: International Prospective Register of Systematic Reviews (PROSPERO) registry (CRD42021218997).

The Immunomodulatory Functions of BTK Inhibition in the Central Nervous System

Bruton's tyrosine kinase (BTK) is a central signaling node in B cells. BTK inhibition has witnessed great success in the treatment of B-cell malignancies. Additionally, in the immune system, BTK is also a prominent component linking a wide variety of immune-related pathways. Therefore, more and more studies attempting to dissect the role of BTK in autoimmune and inflammation progression have emerged in recent years. In particular, BTK expression was also found to be elevated within the central nervous system (CNS) during neuroinflammation. BTK inhibitors are capable of crossing the blood-brain barrier rapidly to modulate B cell functions, attenuate microglial activities and affect NLRP3 inflammasome pathways within the CNS to improve the outcome of diseases. Thus, BTK inhibition appears to be a promising approach to modulate dysregulated inflammation in the CNS and alleviate destruction caused by excessive inflammatory responses. This review will summarize the immunomodulatory mechanisms in which BTK is involved in the development of neurological diseases and discuss the therapeutic potential of BTK inhibition for the treatment of neuroinflammatory pathology.

Old and New Facts and Speculations on the Role of the B Cell Receptor in the Origin of Chronic Lymphocytic Leukemia

The engagement of the B cell receptor (BcR) on the surface of leukemic cells represents a key event in chronic lymphocytic leukemia (CLL) since it can lead to the maintenance and expansion of the neoplastic clone. This notion was initially suggested by observations of the CLL BcR repertoire and of correlations existing between certain BcR features and the clinical outcomes of single patients. Based on these observations, tyrosine kinase inhibitors (TKIs), which block BcR signaling, have been introduced in therapy with the aim of inhibiting CLL cell clonal expansion and of controlling the disease. Indeed, the impressive results obtained with these compounds provided further proof of the role of BcR in CLL. In this article, the key steps that led to the determination of the role of BcR are reviewed, including the features of the CLL cell repertoire and the fine mechanisms causing BcR engagement and cell signaling. Furthermore, we discuss the biological effects of the engagement, which can lead to cell survival/proliferation or apoptosis depending on certain intrinsic cell characteristics and on signals that the micro-environment can deliver to the leukemic cells. In addition, consideration is given to alternative mechanisms promoting cell proliferation in the absence of BcR signaling, which can explain in part the incomplete effectiveness of TKI therapies. The role of the BcR in determining clonal evolution and disease progression is also described. Finally, we discuss possible models to explain the selection of a special BcR set during leukemogenesis. The BcR may deliver activation signals to the cells, which lead to their uncontrolled growth, with the possible collaboration of other still-undefined events which are capable of deregulating the normal physiological response of B cells to BcR-delivered stimuli.

Acalabrutinib Versus Investigator’s Choice in Relapsed/Refractory Chronic Lymphocytic Leukemia: Final ASCEND Trial Results

Acalabrutinib is a Bruton tyrosine kinase inhibitor approved for patients with chronic lymphocytic leukemia (CLL). ASCEND is the pivotal phase 3 study of acalabrutinib versus investigator’s choice of idelalisib plus rituximab (IdR) or bendamustine plus rituximab (BR) in patients with relapsed/refractory (R/R) CLL. In the primary ASCEND analysis (median 16.1-month follow-up), acalabrutinib showed superior efficacy with an acceptable tolerability profile versus IdR/BR; here, we report final ~4 year follow-up results. Patients with R/R CLL received oral acalabrutinib 100 mg twice daily until progression or unacceptable toxicity, or investigator’s choice of IdR or BR. A total of 310 patients (acalabrutinib, n = 155; IdR, n = 119; BR, n = 36) were enrolled. At median follow-up of 46.5 months (acalabrutinib) and 45.3 months (IdR/BR), acalabrutinib significantly prolonged investigator-assessed progression-free survival (PFS) versus IdR/BR (median, not reached [NR] vs 16.8 months; P < 0.001); 42-month PFS rates were 62% (acalabrutinib) versus 19% (IdR/BR). Median overall survival (OS) was NR (both arms); 42-month OS rates were 78% (acalabrutinib) versus 65% (IdR/BR). Adverse events led to drug discontinuation in 23%, 67%, and 17% of patients in the acalabrutinib, IdR, and BR arms, respectively. Events of clinical interest (acalabrutinib vs IdR/BR) included all-grade atrial fibrillation/flutter (8% vs 3%), all-grade hypertension (8% vs 5%), all-grade major hemorrhage (3% vs 3%), grade ≥3 infections (29% vs 29%), and second primary malignancies excluding nonmelanoma skin cancer (7% vs 2%). At ~4 years follow-up, acalabrutinib maintained favorable efficacy versus standard-of-care regimens and a consistent tolerability profile in patients with R/R CLL.

Beyond ibrutinib: novel BTK inhibitors for the treatment of chronic lymphocytic leukemia

PURPOSE OF THE REVIEW

Ibrutinib was the first Bruton tyrosine kinase inhibitor (BTKi) approved for clinical use, contributing to a dramatic change in the treatment landscape of chronic lymphocytic leukemia (CLL). This review provides an overview of next-generation BTKi that have been recently approved or are being investigated for the treatment of CLL, specifically highlighting differences and similarities compared to ibrutinib.

RECENT FINDINGS

Acalabrutinib presented comparable response rates to ibrutinib with lower rates of adverse events and is currently approved for the treatment of CLL. Zanubrutinib displayed excellent response rates with a lower incidence of BTKi-related adverse events, but major rates of neutropenia, and its approval is awaited. With the aim of overcoming drug resistance, noncovalent BTKi have been developed. Of all the explored agents to date, pirtobrutinib has shown promising results with manageable toxicities.

SUMMARY

For the treatment of CLL, several effective therapeutic strategies to target BTK are or will soon be available: these drugs present different safety profiles, thus making it possible to tailor the treatment choice according to patient's characteristics. Importantly, noncovalent BTKi will provide a therapeutic chance also for those relapsed/refractory CLL patients who are BTKi-resistant and are considered an unmet clinical need.

Management of relapsed/refractory Chronic Lymphocytic Leukemia

The therapeutic landscape for chronic lymphocytic leukemia (CLL) has changed dramatically over the past decade as our understanding of the biology of CLL has advanced, allowing the development of oral therapies targeting key drivers of CLL. Currently, inhibitors of Bruton's Tyrosine Kinase and the BH3 mimetic venetoclax are standards of care for both frontline and relapsed/refractory CLL. Sequencing of available therapies, therefore, has become a major challenge of therapy. In this review, we will focus on the current landscape for the treatment of relapsed/refractory CLL. We will also discuss important considerations when sequencing these available treatments. The recent advances in this disease are significant steps forward, and raise new questions of how these available drugs should be given as well as how we can continue to improve the treatment of CLL.

Approach to a patient with "double refractory" chronic lymphocytic leukemia: "Double, double toil and trouble" (Shakespeare)

As patients continue to live longer with chronic lymphocytic leukemia, it has become evident that there is an unmet treatment need for patients who have progressed on multiple lines of therapy. In this article, we attempt to define the "double refractory" patient as resistant to both Bruton's tyrosine kinase inhibitors (BTKi) and venetoclax for which prognosis is poor and there remains no standard of care. We further examine the mechanism of resistance to these targeted agents and discuss the current landscape for managing this patient population. Finally, we explore data supporting promising new agents, including non-covalent BTKi, chimeric antigen receptor T cells, and additional classes of agents currently in development.

Coexisting conditions and concomitant medications do not affect venetoclax management and survival in chronic lymphocytic leukemia

Background

The question of which parameters may be informative on venetoclax outcome in chronic lymphocytic leukemia (CLL) is still unclear. Furthermore, the choice to treat with venetoclax can be challenging in patients with baseline characteristics or comorbidities that may potentially favor some specific adverse events.

Objectives

This study was aimed to evaluate whether age, fitness status, patients'/disease characteristics, or concomitant medications may predict outcomes in CLL patients receiving venetoclax.

Design

Retrospective observational study.

Methods

Impact of age, presence of Cumulative Illness Rating Scale (CIRS) >6 or severe organ impairment (CIRS3+), Eastern Cooperative Oncology Group-Performance Status (ECOG-PS), renal function, and concomitant medications were retrospectively analyzed on treatment management (definitive discontinuation due to toxicity, discontinuation due to toxicity, Tox-DTD; permanent dose reduction, PDR) and survival [progression free survival (PFS), event free survival (EFS), overall survival (OS)] in unselected patients receiving venetoclax monotherapy in common practice.

Results

A total of 221 relapsed/refractory patients were included. Tox-DTD and PDR were reported in 5.9% and 21.7%, respectively, and were not influenced by any fitness parameter, age, number or type of concomitant medication, baseline neutropenia, or impaired renal function. None of these factors were associated with tumor lysis syndrome (TLS) development. Age and coexisting conditions had no influence on PFS and EFS. At univariate analysis, OS was significantly shorter only in patients with ECOG-PS >1 (p < 0.0001) and elderly (⩾65 years) with CIRS >6 (p = 0.014) or CIRS3+ (p = 0.031). ECOG-PS >1 retained an independent role only for EFS and OS. While Tox-DTD affected all survival outcomes, no differences in PFS were reported among patients permanently reducing dose or interrupting venetoclax for > 7 days.

Conclusion

Clinical outcome with venetoclax is not influenced by comorbidities, patients' clinical characteristics, or concomitant medications. Differently from other targeted therapies, this demonstrates that, except ECOG-PS, none of the parameters generally considered for treatment choice, including baseline neutropenia or impaired renal function, should rule the decision process with this agent. Anyway, if clinically needed, a correct drug management does not compromise treatment efficacy and may avoid toxicity-driven discontinuations.

Plain Language Summary

Chapter 1: Why was this study done? Chapter 2: Which are the main findings of the study? Chapter 3: How these findings may impact on clinical practice? Coexisting conditions and concomitant medications do not affect venetoclax management and survival in chronic lymphocytic leukemia • The question of which parameters may be informative on venetoclax outcome in chronic lymphocytic leukemia is still unclear. Furthermore, the choice to treat with venetoclax can be challenging in patients with baseline characteristics or comorbidities that may potentially favor some specific adverse events (e.g. compromised renal function or baseline neutropenia).• In our large series of patients treated outside of clinical trials, we demonstrated that neither age, fitness, comorbidities nor concomitant medications impact on venetoclax management and survival. Importantly, patients presenting with baseline neutropenia or impaired renal function did not have a higher rate of dose reductions or toxicity-driven discontinuations, thus further underlining that venetoclax may be safely administered even in those categories with no preclusions.• Differently from other targeted agents, our data demonstrate that none of the baseline factors commonly considered in treatment decision process retains a role with venetoclax. Finally, permanent dose reductions and temporary interruptions did not adversely impact PFS suggesting that, if clinically needed, a correct drug management should be adopted with no risk of compromising venetoclax efficacy.

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.

Targeted therapies in CLL/SLL and the cumulative incidence of infection: A systematic review and meta-analysis

Background: Patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) are prone to infections.

Aims: Provide a pooled estimate of the cumulative incidence for infections that fulfilled the criteria associated with severe infectious adverse events for grade 3 or higher (including pneumonia, febrile neutropenia and sepsis) in patients who receive targeted therapies.

Methods: We searched PubMed and EMBASE for randomized controlled trials (RCT) that included patients with CLL/SLL who received targeted therapies and performed a random-effects meta-analysis to estimate the cumulative incidence of infections.

Results: Of 2,914 studies screened, we retrieved 31 which evaluated 11,660 patients. The pooled cumulative incidence of infections for patients who received treatment regimens based on a BTK inhibitors was 19.86%. For patients who received treatment based on rituximab and second generation anti-CD20 monoclonal antibodies, the pooled cumulative incidence of infections was 19.85 and 13.46%, respectively. Regarding PI3K inhibitor-based regimens the cumulative incidence of severe infections was 30.89%. BCL-2 inhibitors had a cumulative incidence of infections of 17.49% while lenalidomide and alemtuzumab had an incidence of 13.33 and 45.09%, respectively. The cumulative incidence of pneumonia ranged from 3.01 to 8.45% while febrile neutropenia ranged from 2.68 to 10.80%. Regarding sepsis, the cumulative incidence ranged from 0.9 to 4.48%.

Conclusion: Patients with CLL/SLL who receive targeted therapies may develop severe infections at significant rates that, in addition to disease stage and other complications, depend on the mechanism of action of the used drug. Surveillance for infections and development of effective prophylactic strategies are critical for patients with CLL/SLL who receive targeted therapies.

Systematic Review Registration: [https://systematicreview.gov/], identifier [registration number]

Determining drug dose in the era of targeted therapies: playing it (un)safe?

Targeted therapies against phosphatidylinositol 3-kinase (PI3K), Bruton’s tyrosine kinase (BTK), and B-cell lymphoma-2 (BCL-2) are approved for chronic lymphocytic leukemia (CLL). Since approval of the first-in-class drugs, next-generation agents have become available and are continuously under development. While these therapies act on well-characterized molecular targets, this knowledge is only to some extent taken into consideration when determining their dose in phase I trials. For example, BTK occupancy has been assessed in dose-finding studies of various BTK inhibitors, but the minimum doses that result in full BTK occupancy were not determined. Although targeted agents have a different dose–response relationship than cytotoxic agents, which are more effective near the maximum tolerated dose, the traditional 3 + 3 toxicity-driven trial design remains heavily used in the era of targeted therapies. If pharmacodynamic biomarkers were more stringently used to guide dose selection, the recommended phase II dose would likely be lower as compared to the toxicity-driven selection. Reduced drug doses may lower toxicity, which in some cases is severe for these agents, and are supported by retrospective studies demonstrating non-inferior outcomes for patients with clinically indicated dose reductions. Here, we review strategies that were used for dose selection in phase I studies of currently approved and select investigational targeted therapies in CLL, and discuss how our initial clinical experience with targeted therapies have pointed to dose reductions, intermittent dosing, and drug combinations as strategies to overcome treatment intolerance and resistance.

Risk of cutaneous adverse events in cancer patients treated with phosphatidylinositol-3-kinase inhibitors: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Cutaneous adverse effects (AEs) are common following the phosphoinositide-3-kinase (PI3K) inhibitors treatment. We aim to estimate the incidence and risk of PI3K inhibitor-related cutaneous AEs.

METHODS

The protocol was submitted to the PROSPERO registry. We searched ClinicalTrials.gov and international databases up to July 29, 2022. Meta-analysis was conducted by using risk ratios (RRs) with 95% confidence intervals (CIs).

RESULTS

Fourteen randomized controlled trials (RCTs) comprising 3877 patients were analyzed in this study. Compared with control arms, PI3K inhibitors showed a significant increase in the risk of all-grade rash, high-grade rash, and serious rash events (RR 2.29, 95% CI 1.58-3.31, p < 0.00001; RR 9.34, 95% CI 4.21-20.69, p < 0.00001; RR 5.11, 95% CI 2.11-12.36, p = 0.0003). The overall incidences of all-grade rash and high-grade rash were 26.2% (592/2257) and 4.4% (66/1487). Subgroup analyses of all-grade rash according to cancer types and PI3K inhibitor assignations identified the significant associations. PI3K inhibitors also significantly increased the risk of pruritus and dry skin (RR 1.63, 95% CI 1.14-2.33, p = 0.007; RR 3.34, 95% CI 2.30-4.85, p < 0.00001), with incidences of 13.4% (284/2115) and 9.8% (141/1436) in the treatment group.

CONCLUSION

There is a significantly increased risk of some cutaneous AEs in patients using PI3K inhibitors. Advance intervention is recommended in case of severe and life-threatening events. Further research is required to investigate the risk factors and pathogenesis.

Atrial Fibrillation and Cancer Patients: Mechanisms and Management

PURPOSE OF REVIEW

Cancer-related mortality has significantly declined over the past several decades as a result of improved screening, diagnostics, and therapeutics. Although cancer patients and survivors are living longer, there is increased risk of both short-term and long-term cardiovascular complications, including arrhythmia. In this review, we highlight the current evidence detailing the connections between atrial fibrillation and cancer, provide insight into the mechanisms driving this relationship, and share practical considerations for the management of atrial fibrillation in cancer patients and cancer survivors.

RECENT FINDINGS

Atrial fibrillation is an increasingly recognized condition among cancer patients, with epidemiological data showing increased incidence and worse outcomes in patients with cancer. Studies also describe a bidirectional relationship between cancer and atrial fibrillation, attributable in part to shared risk factors but also potentially due to shared biology. Cancer treatment-associated arrhythmia is an active area of investigation, with ongoing research to identify the mechanisms and pathophysiology behind this phenomenon. Furthermore, management of atrial fibrillation in patients with cancer presents unique challenges, particularly in management of anti-coagulation. Cancer patients have increased risk of developing atrial fibrillation due to the shared risk factors and biology of the two conditions. Moreover, various cancer therapeutics are known to be arrhythmogenic; however, mechanisms remain unclear. Further research is needed to better understand the pathophysiology of atrial fibrillation in cancer patient in order to establish prevention and treatment strategies specific to this population.

Approved and emerging Bruton's tyrosine kinase inhibitors for the treatment of chronic lymphocytic leukemia

INTRODUCTION

The Bruton's tyrosine kinase (BTK) pathway has proven to be an effective and transformative therapeutic target in the treatment of chronic lymphocytic leukemia (CLL), fueling the growth of BTK inhibitors (BTKis) and landmark approval of first-generation BTKi, ibrutinib. However, ibrutinib's side effect profile left an unmet need for BTKis with improved tolerability thus spurring the subsequent development of second-generation acalabrutinib and zanubrutinib. The treatment landscape continues to evolve with studies using BTKi combination therapies, notably with venetoclax, with and without an anti-CD20 monoclonal antibody as well as third generation BTKis aimed to overcome BTKi resistance.

AREAS COVERED

This article details the current literature highlighting the efficacy, toxicities, and potential therapeutic combinations of approved and preclinical BTKis.

EXPERT OPINION

BTKis have signaled the start of a new treatment paradigm in CLL and improved clinical outcomes especially for patients with high-risk disease. However, drug resistance, low CR rates, and indefinite treatment necessitate the development of novel BTKis and fixed duration combination therapy. The results from recently completed and ongoing clinical trials are eagerly awaited with the potential promise of reduced treatment durations and financial burden while achieving durable remissions.

Selecting the optimal BTK inhibitor therapy in CLL: rationale and practical considerations

Bruton's tyrosine kinase (BTK) inhibitors have dramatically changed the treatment of newly diagnosed and relapsed/refractory chronic lymphocytic leukemia (CLL). Ibrutinib, acalabrutinib, and zanubrutinib are Food and Drug Administration (FDA)-approved BTK inhibitors that have all demonstrated progression-free survival (PFS) benefit compared with chemoimmunotherapy. The efficacy of these agents compared to one another is under study; however, current data suggest they provide similar efficacy. Selectivity for BTK confers different adverse effect profiles, and longer follow-up and real-world use have characterized side effects over time. The choice of BTK inhibitor is largely patient-specific, and this review aims to highlight the differences among the agents and guide the choice of BTK inhibitor in clinical practice.

Managing the Risk of Infection in Chronic Lymphocytic Leukemia in the Era of New Therapies

PURPOSE OF REVIEW

Patients diagnosed with CLL have an increased susceptibility to infections. Over the years, there has been a shift of the treatment arsenal to an increasing use of chemotherapy-free regimens, particularly small molecule inhibitors. These therapies have proven to be effective and have a favorable toxicity profile. Infections continue to represent a significant complication in the era of novel therapies.

RECENT FINDINGS

Recent studies continue to bring new insights into the effects of modern therapies on the immune system. Evidence supporting infection prevention strategies is scarce. We will review the available recommendations to prevent infections in patients with CLL treated with novel therapies. New CLL therapies are broadly adopted in routine practice, requiring optimization of their side effects. Timely prevention, recognition, and treatment of infections should remain an important aspect of the standard management of a patient with CLL.

Risk of bleeding associated with BTK inhibitor monotherapy: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

The risk of bleeding associated with Bruton's tyrosine kinase inhibitor (BTKi) monotherapy remains to be understood. This systematic review aims to evaluate BTKi monotherapy related bleeding risk.

RESEARCH DESIGN AND METHODS

PubMed, Embase, and CENTRAL were searched up to December 5, 2021. We included randomized controlled trials (RCTs) comparing BTKi monotherapy with control drugs or placebo, or comparing different BTKi monotherapies. The risk ratios (RR) with 95% confidence intervals (95% CI) were calculated.

RESULTS

10 studies with 3139 patients were included. Ibrutinib (vs. control drugs or placebo) significantly increased the risk of overall bleeding and major bleeding (RR=2.22, 95% CI 1.80-2.75, P<0.00001; RR=1.80, 95% CI 1.02-3.18, P=0.04, respectively). Acalabrutinib (vs. control drugs) had a significantly increased overall bleeding risk (RR=3.45, 95% CI 2.39-4.99, p<0.00001). A significant difference was found in overall bleeding between ibrutinib and acalabrutinib (RR=1.35, 95% CI 1.11-1.64, P=0.002). Compared to zanubrutinib, ibrutinib tended to increase the risk of major bleeding (RR=1.55, 95% CI 0.57-4.18, P=0.39).

CONCLUSIONS

Ibrutinib and acalabrutinib (vs. control drugs or placebo) have a higher risk of bleeding and overall bleeding, respectively. Limited evidence suggests that ibrutinib (vs. acalabrutinib) significantly increases overall bleeding risk, but the differences are not observed in other comparisons.

Use of BTK Inhibitors in Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma (CLL/SLL): A Practical Guidance

The treatment landscape of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) has changed significantly since the development of oral Bruton's tyrosine kinase (BTK) inhibitors. While chemoimmunotherapy was previously the standard of care for first-line treatment, BTK inhibitors have proven to be a highly effective and safe therapeutic option for CLL/SLL, and now constitute one of the preferred first-line options. Ibrutinib, the first approved covalent BTK inhibitor in CLL/SLL, has the most long-term data supporting its efficacy in CLL/SLL treatment although is associated with increased risk of cardiovascular and hemorrhage adverse events due to off-target kinase inhibition. The second-generation covalent BTK inhibitors, including acalabrutinib and zanubrutinib, are more selective to BTK with less off-target effects. Resistance to covalent BTK inhibitors may emerge over time due to mutations in BTK and downstream kinases. Novel non-covalent BTK inhibitors currently being studied are showing promising activities to overcome such resistance. In this review, we discuss the role of BTK inhibitors in treatment of CLL/SLL, review the data that led to approval of BTK inhibitors in CLL/SLL, outline the toxicity profile of each approved BTK inhibitor and management, and give practical guidance on how to select the most appropriate agent for treatment.

Integrin Signaling Shaping BTK-Inhibitor Resistance

Integrins are adhesion molecules that function as anchors in retaining tumor cells in supportive tissues and facilitating metastasis. Beta1 integrins are known to contribute to cell adhesion-mediated drug resistance in cancer. Very late antigen-4 (VLA-4), a CD49d/CD29 heterodimer, is a beta1 integrin implicated in therapy resistance in both solid tumors and haematological malignancies such as chronic lymphocytic leukemia (CLL). A complex inside-out signaling mechanism activates VLA-4, which might include several therapeutic targets for CLL. Treatment regimens for this disease have recently shifted towards novel agents targeting BCR signaling. Bruton’s tyrosine kinase (BTK) is a component of B cell receptor signaling and BTK inhibitors such as ibrutinib are highly successful; however, their limitations include indefinite drug administration, the development of therapy resistance, and toxicities. VLA-4 might be activated independently of BTK, resulting in an ongoing interaction of CD49d-expressing leukemic cells with their surrounding tissue, which may reduce the success of therapy with BTK inhibitors and increases the need for alternative therapies. In this context, we discuss the inside-out signaling cascade culminating in VLA-4 activation, consider the advantages and disadvantages of BTK inhibitors in CLL and elucidate the mechanisms behind cell adhesion-mediated drug resistance.

Hypertension and incident cardiovascular events after next-generation BTKi therapy initiation

BACKGROUND

Post-market analyses revealed unanticipated links between first-generation Bruton's tyrosine kinase inhibitor (BTKi) therapy, ibrutinib, and profound early hypertension. Yet, whether this is seen with novel selective second (next)-generation BTKi therapy, acalabrutinib, is unknown.

METHODS

Leveraging a large cohort of consecutive B cell cancer patients treated with acalabrutinib from 2014 to 2020, we assessed the incidence and ramifications of new or worsened hypertension [systolic blood pressure (SBP) ≥ 130 mmHg] after acalabrutinib initiation. Secondary endpoints were major cardiovascular events (MACE: arrhythmias, myocardial infarction, stroke, heart failure, cardiac death) and disease progression. Observed incident hypertension rates were compared to Framingham heart-predicted and ibrutinib-related rates. Multivariable regression and survival analysis were used to define factors associated with new/worsened hypertension and MACE, and the relationship between early SBP increase and MACE risk. Further, the effect of standard antihypertensive classes on the prevention of acalabrutinib-related hypertension was assessed.

RESULTS

Overall, from 280 acalabrutinib-treated patients, 48.9% developed new/worsened hypertension over a median of 41 months. The cumulative incidence of new hypertension by 1 year was 53.9%, including 1.7% with high-grade (≥ 3) hypertension. Applying the JNC 8 cutoff BP of ≥ 140/90 mmHg, the observed new hypertension rate was 20.5% at 1 year, > eightfold higher than the Framingham-predicted rate of 2.4% (RR 8.5, P < 0.001), yet 34.1% lower than ibrutinib (12.9 observed-to-expected ratio, P < 0.001). In multivariable regression, prior arrhythmias and Black ancestry were associated with new hypertension (HR 1.63, HR 4.35, P < 0.05). The degree of SBP rise within 1 year of treatment initiation predicted MACE risk (42% HR increase for each + 5 mmHg SBP rise, P < 0.001). No single antihypertensive class prevented worsened acalabrutinib-related hypertension.

CONCLUSIONS

Collectively, these data suggest that hypertension may be a class effect of BTKi therapies and precedes major cardiotoxic events.

International Consensus Statement on the Management of Cardiovascular Risk of Bruton's Tyrosine Kinase Inhibitors in CLL

Bruton's tyrosine kinase inhibitors (BTKis) have altered the treatment landscape for chronic lymphocytic leukemia (CLL) by offering effective and well-tolerated therapeutic options. However, since the approval of ibrutinib, concern has risen regarding the risk of cardiovascular (CV) adverse events including atrial fibrillation (AF), hypertension, and heart failure. Newer BTKis appear to have lower cardiovascular risks, but data are limited. It is important to understand the risks posed by BTKis and how those risks interact with individual patients, and we convened a panel of physicians with expertise in CLL and cardiovascular toxicities in oncology to develop evidence-based consensus recommendations for community hematologists and oncologists. Care providers should thoroughly assess a patient's cardiovascular risk level before treatment initiation including established cardiovascular diseases and risk factors and performing investigations, dependent on pre-existing diseases and risk factors, including an electrocardiogram (ECG). For patients with high CV risk, BTKi treatment is often appropriate in consultation with a multidisciplinary team (MDT), and more selective BTKis including acalabrutinib and zanubrutinib are preferred. BTKi treatment should generally be avoided in patients with a history of heart failure. Ibrutinib should be avoided in patients with a history of ventricular arrhythmias, but the risk of newer drugs is not yet known. Finally, an MDT is crucial to help manage emerging toxicities with the goal of maintaining BTKi therapy, if possible. Optimizing heart failure, arrhythmia, and hypertension control will likely improve tolerance and maintenance of BTKi therapy. However, additional studies are needed to identify the most optimal strategy for these drugs.

SOHO State of the Art Updates and Next Questions | Management of Most Difficult Cases of Chronic Lymphocytic Leukemia: Relapse After Both BTK and BCL2 Inhibition and Richter Transformation

The introduction of targeted therapies in chronic lymphocytic leukemia (CLL) has ushered in a new era in which patients achieve better control of their disease, survive longer, and experience fewer toxicities than before. Despite this progress, a subgroup of patients with CLL will develop resistance to both Bruton tyrosine kinase (BTK) and B-cell lymphoma 2 inhibitors. In addition, a subgroup of CLL cases will transform into aggressive lymphoma - called Richter transformation - either before or during targeted therapy. These two subgroups of patients have a poor prognosis, and available therapies lead to long-term remission in only a minority of patients. In this paper, two cases are presented that are reflective of these difficult scenarios. In the first case, a patient with CLL, complex karyotype, del 17p, and a mutation in TP53 experiences progression after ibrutinib, venetoclax, bendamustine, rituximab, and idelalisib. In the second case, a patient with CLL and del 17p develops a Richter transformation to diffuse large B-cell lymphoma after treatment with obinutuzumab, chlorambucil, ibrutinib, venetoclax, and idelalisib. The aggressive lymphoma is refractory to chemoimmunotherapy, and she expires. The literature pertaining to these two scenarios is reviewed, including the role of available targeted therapies, chemoimmunotherapy, and hematopoietic cell transplantation. Emerging novel therapies, including reversible BTK inhibitors and CAR T cell therapy, are discussed.

The potential of pirtobrutinib in multiple B-cell malignancies

Bruton’s tyrosine kinase (BTK) is a critical downstream signaling element from the B-cell receptor (BCR) that has been effectively inhibited in B-cell cancers by irreversible, covalent inhibitors including ibrutinib and acalabrutinib. All FDA-approved covalent BTK inhibitors rely on binding to the cysteine 481 (C481) amino acid within the active site of BTK, thus rendering it inert. While covalent BTK inhibitors have been very successful in multiple B-cell malignancies, improving both overall survival and progression-free survival relative to chemoimmunotherapy in phase 3 trials, they can be limited by intolerance and disease progression. Pirtobrutinib is a novel, highly selective, and non-covalent BTK inhibitor that binds independently of C481, and in a recent, first-in-human phase 1/2 clinical trial was shown to be extremely well tolerated and lead to remissions in relapsed/refractory patients with multiple B-cell malignancies. Here, we review the pharmacologic rationale for pursuing non-covalent BTK inhibitors, the clinical need for such inhibitors, existing safety, and resistance mechanism data for pirtobrutinib, and the forthcoming clinical trials that seek to define the clinical utility of pirtobrutinib, which has the potential to fulfill multiple areas of unmet clinical need for patients with B-cell malignancies.

Cardiovascular adverse events in patients with chronic lymphocytic leukemia receiving acalabrutinib monotherapy: pooled analysis of 762 patients

Cardiovascular (CV) toxicities of the Bruton tyrosine kinase (BTK) inhibitor ibrutinib may limit use of this effective therapy in patients with chronic lymphocytic leukemia (CLL). Acalabrutinib is a second-generation BTK inhibitor with greater BTK selectivity. This analysis characterizes pooled CV adverse events (AE) data in patients with CLL who received acalabrutinib monotherapy in clinical trials (clinicaltrials gov. Identifier: NCT02029443, NCT02475681, NCT02970318 and NCT02337829). Acalabrutinib was given orally at total daily doses of 100-400 mg, later switched to 100 mg twice daily, and continued until disease progression or toxicity. Data from 762 patients (median age: 67 years [range, 32-89]; median follow-up: 25.9 months [range, 0-58.5]) were analyzed. Cardiac AE of any grade were reported in 129 patients (17%; grade ≥3, n=37 [5%]) and led to treatment discontinuation in seven patients (1%). The most common any-grade cardiac AE were atrial fibrillation/flutter (5%), palpitations (3%), and tachycardia (2%). Overall, 91% of patients with cardiac AE had CV risk factors before acalabrutinib treatment. Among 38 patients with atrial fibrillation/flutter events, seven (18%) had prior history of arrhythmia or atrial fibrillation/flutter. Hypertension AE were reported in 67 patients (9%), 43 (64%) of whom had a preexisting history of hypertension; no patients discontinued treatment due to hypertension. No sudden cardiac deaths were reported. Overall, these data demonstrate a low incidence of new-onset cardiac AE with acalabrutinib in patients with CLL. Findings from the head-to-head, randomized trial of ibrutinib and acalabrutinib in patients with highrisk CLL (clinicaltrials gov. Identifier: NCT02477696) prospectively assess differences in CV toxicity between the two agents.

NCCN Guidelines® Insights: Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma, Version 3.2022

The treatment landscape of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) has significantly evolved in recent years. Targeted therapy with Bruton's tyrosine kinase (BTK) inhibitors and BCL-2 inhibitors has emerged as an effective chemotherapy-free option for patients with previously untreated or relapsed/refractory CLL/SLL. Undetectable minimal residual disease after the end of treatment is emerging as an important predictor of progression-free and overall survival for patients treated with fixed-duration BCL-2 inhibitor-based treatment. These NCCN Guidelines Insights discuss the updates to the NCCN Guidelines for CLL/SLL specific to the use of chemotherapy-free treatment options for patients with treatment-naïve and relapsed/refractory disease.

Long-term follow-up and future direction on the management of chronic lymphocytic leukemia/small lymphocytic leukemia

Objective

Chronic lymphocytic leukemia and small lymphocytic lymphoma remain the most prevalent adult leukemia in Western countries. Novel therapeutics have established long-term efficacy and have changed the landscape in patient management. In contrast, novel approaches pose opportunities for patients to be treated for finite durations. In this manuscript, we highlight long-term safety and efficacy data with Bruton's tyrosine kinase inhibitors and combination BCL2 + anti-CD20 therapies. We also offer key considerations for treatment selection and outline ongoing trials which may continue to expand therapeutic options and approaches.

Data sources

An electronic search of the PubMed database was performed to obtain key literature in chronic lymphocytic leukemia and small lymphocytic lymphoma published using the following search terms: chronic lymphocytic leukemia/small lymphocytic lymphoma, Richter syndrome, and histologic transformation. The search results were narrowed by selecting studies in humans published in English. Results were confined to the following article types: Clinical Trial, Phase II; Clinical Trial, Phase III; Clinical Trial, Phase IV; Guideline; Randomized Controlled Trial; Meta-Analysis; Systematic Reviews; and Validation Studies.

Data summary

Chronic lymphocytic leukemia and small lymphocytic lymphoma are different manifestations of the same disease and are managed in much the same way. Bruton's tyrosine kinase inhibitors have demonstrated long and durable efficacy benefits in patients with newly diagnosed chronic lymphocytic leukemia/small lymphocytic lymphoma and in the relapsed/refractory setting. Despite these benefits, long terms adverse events have posed challenges for patients and have led to treatment discontinuations. Additionally, the use of monotherapy Bruton's tyrosine kinase inhibitor's requires chronic use of the medications leading to added financial implications. BCL2 inhibition with venetoclax in combination with anti-CD20 monoclonal antibodies has offered a novel and finite treatment approach in frontline and relapsed chronic lymphocytic leukemia/small lymphocytic lymphoma. Ongoing clinical trials are in investigating this modality further to enhance durable responses utilizing a combination Bruton's tyrosine kinase inhibitor's and BCL2 inhibitors.

Conclusion

The treatment armamentarium of chronic lymphocytic leukemia/small lymphocytic lymphoma continues to evolve. Despite the long term, durable responses with Bruton's tyrosine kinase inhibitor's, it is likely that finite treatment durations could become the standard of care as a result of continued, long-term responses.

Immunoglobulin gene sequence analysis in chronic lymphocytic leukemia: the 2022 update of the recommendations by ERIC, the European Research Initiative on CLL

The somatic hypermutation (SHM) status of the clonotypic immunoglobulin heavy variable (IGHV) gene is a critical biomarker for assessing the prognosis of patients with chronic lymphocytic leukemia (CLL). Importantly, independent studies have documented that IGHV SHM status is also a predictor of responses to therapy, including both chemoimmunotherapy (CIT) and novel, targeted agents. Moreover, immunogenetic analysis in CLL has revealed that different patients may express (quasi)identical, stereotyped B cell receptor immunoglobulin (BcR IG) and are classified into subsets based on this common feature. Patients in certain stereotyped subsets display consistent biology, clinical presentation, and outcome that are distinct from other patients, even with concordant IGHV gene SHM status. All of the above highlights the relevance of immunogenetic analysis in CLL, which is considered a cornerstone for accurate risk stratification and clinical decision making. Recommendations for robust immunogenetic analysis exist thanks to dedicated efforts by ERIC, the European Research Initiative on CLL, covering all test phases, from the pre-analytical and analytical to the post-analytical, pertaining to the analysis, interpretation, and reporting of the findings. That said, these recommendations apply to Sanger sequencing, which is increasingly being superseded by next generation sequencing (NGS), further underscoring the need for an update. Here, we present an overview of the clinical utility of immunogenetics in CLL and update our analytical recommendations with the aim to assist in the refined management of patients with CLL.

Bendamustine: A review of pharmacology, clinical use and immunological effects (Review)

Bendamustine is an alkylating agent classified into the group of nitrogen mustard analogues, synthesized almost sixty years ago. It was registered in former East Germany in 1971 and approved by the US Food and Drug Administration in 2008 for treatment of chronic lymphocytic leukemia and indolent B-cell non-Hodgkin lymphoma. Considering its beneficial properties in the therapy of relapsed or refractory hematological malignancies, synergistic effects with other antineoplastic agents and increasing recent reports on its immunomodulatory effects, bendamustine has once again gained its justified attention. The uniqueness of bendamustine-mediated effects should be observed keeping in mind its distinctive structure with structural similarities to both alkylating agents and purine analogs. In the present review, the current knowledge on the use of bendamustine in oncology, its pharmacokinetics, mechanism of action and toxicity was summarized. In addition, its immune-modulating effects that have not been fully elucidated so far are emphasized, hoping to encourage further investigations of this unique drug.

BTK inhibitor selection for chronic lymphocytic leukemia: which drug for which patient?

INTRODUCTION

The development of BTK inhibitors has revolutionized the management of CLL. Currently, there are 3 BTK inhibitors available to treat CLL: ibrutinib, acalabrutinib, and zanubrutinib (the latter not yet approved for this disease but included in the NCCN guidelines). In this review, we will elucidate our approach to the selection of BTK inhibitor and provide insight into the future of BTK directed therapy.

AREAS COVERED

This review utilizes data from published prospective trials, specifically RESONATE, RESONATE-2, ELEVATE-TN, ASCEND, ELEVATE-RR, and the ongoing FLAIR, SEQUOIA and ALPINE trials.

EXPERT OPINION

The choice of BTK inhibitor is guided by the setting (frontline vs relapsed) in conjunction with patient disease characteristics and comorbidities. In this review, we will elucidate our approach to the selection of BTK inhibitor and provide insight into the future of BTK directed therapy.

Acalabrutinib-Related Cardiac Toxicities in Patients with Chronic Lymphocytic Leukemia: A Meta-Analysis of Randomized Controlled Trials

Acalabrutinib, a second-generation and more selective Bruton's tyrosine kinase inhibitor, was developed to potentiate efficacy while minimizing ibrutinib-associated side effects. We undertook a systematic review and meta-analysis of randomized clinical trials to determine the risks of acalabrutinib-related cardiac toxicities in patients with chronic lymphocytic leukemia. Patients on acalabrutinib experienced higher risk of any-grade cardiac events (risk ratio, 1.75; p = 0.01) while there was a considerable trend toward statistical significance in the risk of any-grade atrial fibrillation (risk ratio, 2.56; p = 0.05). There was no significant increase in the risk of hypertension or high-grade cardiac events or atrial fibrillation in the acalabrutinib group.

Cardiotoxicity of BTK inhibitors: ibrutinib and beyond

INTRODUCTION

The development of Bruton<apos;>s Tyrosine Kinase (BTK) inhibitors has transformed the treatment of B-cell malignancies and other non-malignant conditions. Management of the unique cardiotoxic profile of these agents requires prompt recognition and a multi-disciplinary approach.

AREAS COVERED

The increasing indications and addition of newer agents to clinical practice and emergence of BTK inhibitor-related cardiac adverse events have complicated the management decisions for utilization of this class of therapy. We review the incidence, mechanisms, and management approaches for BTK inhibitor-related atrial fibrillation, hypertension, and ventricular arrhythmias.

EXPERT OPINION

The newer BTK inhibitor acalabrutinib represents a new standard of care in front-line chronic lymphocytic leukemia (CLL) given the results of the ELEVATE-RR trial demonstrating comparable efficacy and a more favorable toxicity profile especially with regard to cardiac adverse events as compared to ibrutinib. Often not recognized by clinicians, BTK inhibitor-induced hypertension is common and can be severe, requiring prompt recognition and initiation or adjustment of anti-hypertensive medications to prevent major adverse cardiac outcomes. Novel BTK inhibitors in development are being designed to overcome the patterns of resistance from first-generation agents and to minimize off-target kinase activity, with promising toxicity profiles in early trials.

Chronic Lymphocytic Leukemia: Chemotherapy Free and Other Novel Therapies Including CAR T

OPINION STATEMENT

Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults. Most individuals diagnosed with CLL will not need treatment immediately but over time the clonal B cells infiltrate the bone marrow, lymph nodes, liver, and spleen, causing anemia, thrombocytopenia, systemic symptoms, and increased risk for infections. When clonal B cells begin adversely affecting other organs, treatment is warranted. Therapy for CLL has undergone a paradigm shift away from chemotherapy-based regimens to targeted therapy with small-molecule inhibitors. B-cell receptor (BCR) signaling plays a key role in CLL. BCR signaling occurs via many factors including Bruton's tyrosine kinase (BTK), phosphatidylinositol 3-kinase (PI3K), phosphatidylinositol-4,5-bisphosphonate phosphodiesterase gamma-2 (PLCγ2), and CD19. CLL cells also express high levels of B-cell lymphoma or leukemia 2 (BCL2). Drugs that interfere with these pathways, such as ibrutinib, venetoclax, and idelalisib, have improved clinical outcomes. For any CLL patient that meets criteria for treatment, after evaluating for prognostic cytogenetic abnormalities, oral BTK inhibitors or venetoclax in combination with anti-CD20 therapy are considered first-line therapy. It is important to note that these novel therapies are particularly preferred for patients with TP53 mutations or deletion of the small arm of chromosome 17 (del(17p)), as those patients usually are chemotherapy refractory or display short remissions to chemotherapy. Nevertheless, patients without high-risk features such as TP53 abnormalities also benefit from novel agents. Following relapse, depending on the primary oral agent used, BTK inhibitors, venetoclax in combination with anti-CD20 antibodies, or PI3K inhibitors are preferred.

New Treatment Options for Newly-Diagnosed and Relapsed Chronic Lymphocytic Leukemia

OPINION STATEMENT

The better understanding of the biology of chronic lymphocytic leukemia (CLL) gained over the past decade has led to the development and introduction of several targeted drugs, with an demonstrable improvement in the prognosis for this currently incurable condition. Currently, Bruton's tyrosine kinase (BTK) inhibitors, phosphoinositide 3-kinase (PI3K) inhibitors, venetoclax, and CD20 monoclonal antibodies are the key elements in the treatment of both previously untreated and relapsed/refractory CLL patients. Ibrutinib was the first BTK inhibitor approved for clinical use, and showed excellent efficacy and an acceptable safety profile. Following this, the better-tolerated second-generation irreversible BTK inhibitors acalabrutinib and zanubrutinib have been introduced for the treatment of lymphoid malignancies, and acalabrutinib was approved for CLL. When used as single drugs, BTK inhibitors are given continuously until unacceptable toxicity or disease progression; however, when combined with venetoclax and/or CD20 antibodies, they induce deeper response and can be given for a limited time. Recently, promising new reversible BTK inhibitors pirtobrutinib and nemtabrutinib were discovered, and these seem to be more active and better tolerated than their irreversible predecessors. However, they are in an early phase of development and are not currently approved for CLL. The phosphatidylinositol 3-kinase (PI3K) inhibitors idelalisib and duvelisib are highly effective in patients with relapsed CLL, including high-risk disease. The major limitations for their use are adverse events, mostly of autoimmune origin (hepatitis, enteritis/colitis, and pneumonitis). Otherwise, cellular therapies like allogeneic hematopoietic stem cell transplantation and chimeric antigen receptor (CAR) T cells and bispecific monoclonal antibodies offer promise for patients who have failed BTK inhibitors and venetoclax treatment. In the coming years, it is likely that novel targeted therapies will replace immunochemotherapy regimens in most patients.

Real-world management of targeted therapies in chronic lymphocytic leukemia

The advent of novel targeted therapies, including B-cell receptor (BCR) pathway and B-cell lymphoma 2 (BCL2) inhibitors, has substantially changed the treatment paradigm for chronic lymphocytic leukemia (CLL). Although targeted therapies have improved outcomes compared to traditional chemoimmunotherapy in the front-line and relapsed or refractory settings, they are associated with resistance mutations and suboptimal outcomes in certain high-risk patients. Additionally, targeted therapies are associated with drug interactions and unique adverse effect profiles which can be challenging for patients and clinicians to manage. Ongoing studies continue to address questions regarding optimal sequencing of therapies, the role of treatment combinations, and the efficacy of next-generation novel agents. This review provides a comprehensive overview regarding the clinical management of targeted therapies for CLL and applies current literature to clinical practice.

PI3K Inhibitors for the Treatment of Chronic Lymphocytic Leukemia: Current Status and Future Perspectives

Phosphoinositide 3-kinases (PI3Ks) signaling regulates key cellular processes, such as growth, survival and apoptosis. Among the three classes of PI3K, class I is the most important for the development, differentiation and activation of B and T cells. Four isoforms are distinguished within class I (PI3Kα, PI3Kβ, PI3Kδ and PI3Kγ). PI3Kδ expression is limited mainly to the B cells and their precursors, and blocking PI3K has been found to promote apoptosis of chronic lymphocytic leukemia (CLL) cells. Idelalisib, a selective PI3Kδ inhibitor, was the first-in-class PI3Ki introduced into CLL treatment. It showed efficacy in patients with del(17p)/TP53 mutation, unmutated IGHV status and refractory/relapsed disease. However, its side effects, such as autoimmune-mediated pneumonitis and colitis, infections and skin changes, limited its widespread use. The dual PI3Kδ/γ inhibitor duvelisib is approved for use in CLL patients but with similar toxicities to idelalisib. Umbralisib, a highly selective inhibitor of PI3Kδ and casein kinase-1ε (CK1ε), was found to be efficient and safe in monotherapy and in combination regimens in phase 3 trials in patients with CLL. Novel PI3Kis are under evaluation in early phase clinical trials. In this paper we present the mechanism of action, efficacy and toxicities of PI3Ki approved in the treatment of CLL and developed in clinical trials.

Acalabrutinib: a bruton tyrosine kinase inhibitor for the treatment of chronic lymphocytic leukemia

INTRODUCTION

: The first-in-class Bruton tyrosine kinase (BTK), ibrutinib, demonstrated remarkable activity in chronic lymphocytic leukemia (CLL). However, its toxicity profile renders it potentially inappropriate for use in patients with bleeding or cardiovascular disorders. In response to the high demand for a safer and efficient BTK inhibitor, with improved toxicity profile, acalabrutinib as a second-generation irreversible BTK inhibitor has been approved for the treatment of CLL.

AREAS COVERED

: This review examines the activity of acalabrutinib in treating treatment-naïve and relapsed refractory CLL and its toxicity profile when compared to ibrutinib and other drugs. It will examine the outcomes of the ELEVATE-TN, ASCEND and ELEVATE-RR studies in detail, with a particular focus on the safety and efficacy of acalabrutinib. The strengths and weaknesses of this drug will be highlighted and future directions for research will be identified.

EXPERT OPINION

: In patients with CLL, acalabrutinib demonstrates a superior safety profile than ibrutinib and similar activity. In the first direct comparison of acalabrutinib with ibrutinib in relapsed/refractory CLL, acalabrutinib was found to demonstrate non-inferior progression-free survival, with fewer cardiovascular adverse events.

Recognizing Unmet Need in the Era of Targeted Therapy for CLL/SLL: "What's Past Is Prologue" (Shakespeare)

The management of chronic lymphocytic leukemia (CLL) has undergone unprecedented changes over the last decade. Modern targeted therapies are incorporated into clinical practice. Unfortunately, patients have begun to develop resistance or intolerance to multiple classes. Symptomatic patients previously treated with a BTK inhibitor (BTKi) and venetoclax represent a new and rapidly growing unmet need in CLL. Here, we define unmet needs in a modern treatment context. We also critically review the literature for PI3K inhibitors and chemoimmunotherapy and lack of data to support their utility following BTKis and venetoclax. Finally, we suggest opportunities to ensure the continued innovation for patients with CLL.

Druggable Molecular Pathways in Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL), the most common type of leukemia in adults, is characterized by a high degree of clinical heterogeneity that is influenced by the disease’s molecular complexity. The genes most frequently affected in CLL cluster into specific biological pathways, including B-cell receptor (BCR) signaling, apoptosis, NF-κB, and NOTCH1 signaling. BCR signaling and the apoptosis pathway have been exploited to design targeted medicines for CLL therapy. Consistently, molecules that selectively inhibit specific BCR components, namely Bruton tyrosine kinase (BTK) and phosphoinositide 3-kinase (PI3K) as well as inhibitors of BCL2, have revolutionized the therapeutic management of CLL patients. Several BTK inhibitors and PI3K inhibitors with different modes of action are currently used or are in development in advanced stage clinical trials. Moreover, the restoration of apoptosis by the BCL2 inhibitor venetoclax offers meaningful clinical activity with a fixed-duration scheme. Inhibitors of the BCR and of BCL2 are able to overcome the chemorefractoriness associated with high-risk genetic features, including TP53 disruption. Other signaling cascades involved in CLL pathogenesis, in particular NOTCH signaling and NF-kB signaling, already provide biomarkers for a precision medicine approach to CLL and may represent potential druggable targets for the future. The aim of the present review is to discuss the druggable pathways of CLL and to provide the biological background of the high efficacy of targeted biological drugs in CLL.