Ibrutinib-related bleeding: pathogenesis, clinical implications and management

On the horizon: upcoming new agents for the management of ITP

Treatment of immune thrombocytopenia (ITP) has evolved over the last 20 years in response to our increased understanding of the pathophysiology of this complex immune disorder. New treatments in development have taken advantage of our evolving understanding of the biology of this disease to target new mechanisms and expand the available ways in which to approach patients with this disorder. This review focuses on novel therapeutics in the ITP pipeline and discusses the pathophysiology of ITP that has led to their development.

Translating mechanisms into therapeutic strategies for immune thrombocytopenia (ITP): Lessons from clinical trials

Immune thrombocytopenia (ITP) is an autoimmune disorder that causes a significant reduction in peripheral blood platelet count. Fortunately, due to an increased understanding of ITP, there have been significant improvements in the diagnosis and treatment of these patients. Over the past decade, there have been a variety of proven therapeutic options available for ITP patients, including intravenous immunoglobulins (IVIG), Rituximab, corticosteroids, and thrombopoietin receptor agonists (TPO-RAs). Although the effectiveness of current therapies in treating more than two-thirds of patients, still some patients do not respond well to conventional therapies or fail to achieve long-term remission. Recently, a significant advancement has been made in identifying various mechanisms involved in the pathogenesis of ITP, leading to the development of novel treatments targeting these pathways. It seems that new agents that target plasma cells, Bruton tyrosine kinase, FcRn, platelet desialylation, splenic tyrosine kinase, and classical complement pathways are opening new ways to treat ITP. In this study, we reviewed the pathophysiology of ITP and summarized updates in this population's management and treatment options. We also took a closer look at the 315 ongoing trials to investigate their progress status and compare the effectiveness of interventions. May our comprehensive view of ongoing clinical trials serve as a guiding beacon, illuminating the path towards future trials of different drugs in the treatment of ITP patients.

How we approach the perioperative management of patients with chronic lymphocytic leukaemia receiving continuous cancer-directed therapies

Historically, invasive procedures and surgeries were deferred in patients with haematological malignancies including advanced stage chronic lymphocytic leukaemia (CLL) because of limited life expectancy. However, novel, and often continuous, treatments have markedly improved outcomes in CLL. Some patients may expect years of treatment response and disease control, overcoming the short life expectancy that deters interventionalists. Such patients now often undergo various invasive procedures including major surgery. To inform peri-operative management, we summarize the relevant side effects and drug interactions of continuous CLL therapies, highlight potential surgical risks, and provide recommendations on withholding specific CLL drugs around invasive procedures.

Bruton's Kinase Inhibitors for the Treatment of Immunological Diseases: Current Status and Perspectives

The use of Bruton's tyrosine kinase (BTK) inhibitors has changed the management of patients with B-cell lymphoid malignancies. BTK is an important molecule that interconnects B-cell antigen receptor (BCR) signaling. BTK inhibitors (BTKis) are classified into three categories, namely covalent irreversible inhibitors, covalent reversible inhibitors, and non-covalent reversible inhibitors. Ibrutinib is the first covalent, irreversible BTK inhibitor approved in 2013 as a breakthrough therapy for chronic lymphocytic leukemia patients. Subsequently, two other covalent, irreversible, second-generation BTKis, acalabrutinib and zanubrutinib, have been developed for lymphoid malignancies to reduce the ibrutinib-mediated adverse effects. More recently, irreversible and reversible BTKis have been under development for immune-mediated diseases, including autoimmune hemolytic anemia, immune thrombocytopenia, multiple sclerosis, pemphigus vulgaris, atopic dermatitis, rheumatoid arthritis, systemic lupus erythematosus, Sjögren's disease, and chronic spontaneous urticaria, among others. This review article summarizes the preclinical and clinical evidence supporting the role of BTKis in various autoimmune, allergic, and inflammatory conditions.

Treatment paradigm in Waldenström macroglobulinemia: frontline therapy and beyond

Waldenström macroglobulinemia (WM) is an indolent lymphoplasmacytic lymphoma. Recent strides made in the genomic profiling of patients with WM have led to the identification of many novel therapeutic targets. Patients with WM can present with asymptomatic disease and not all patients require treatment. When criteria for initiating systemic therapy are met, the choice of therapy depends on the tumor genotype (MYD88 and CXCR4 mutation status), patient preference (fixed versus continuous duration therapy, oral versus intravenous route, cost), associated medical comorbidities, and adverse effect profile of the treatment. In the absence of head-to-head comparison between chemoimmunotherapy and Bruton’s tyrosine kinase inhibitors in otherwise fit patients with a MYD88^L265P mutation, our preference is fixed duration therapy with four to six cycles of chemoimmunotherapy with bendamustine–rituximab. In this review, we discuss the role of MYD88 and CXCR4 mutation in treatment selection, and current data for frontline and salvage treatment options in patients with WM.

Rilzabrutinib, an Oral BTK Inhibitor, in Immune Thrombocytopenia

BACKGROUND

Rilzabrutinib, an oral, reversible covalent inhibitor of Bruton's tyrosine kinase, may increase platelet counts in patients with immune thrombocytopenia by means of dual mechanisms of action: decreased macrophage (Fcγ receptor)-mediated platelet destruction and reduced production of pathogenic autoantibodies.

METHODS

In an international, adaptive, open-label, dose-finding, phase 1-2 clinical trial, we evaluated rilzabrutinib therapy in previously treated patients with immune thrombocytopenia. We used intrapatient dose escalation of oral rilzabrutinib over a period of 24 weeks; the lowest starting dose was 200 mg once daily, with higher starting doses of 400 mg once daily, 300 mg twice daily, and 400 mg twice daily. The primary end points were safety and platelet response (defined as at least two consecutive platelet counts of ≥50×10³ per cubic millimeter and an increase from baseline of ≥20×10³ per cubic millimeter without the use of rescue medication).

RESULTS

Sixty patients were enrolled. At baseline, the median platelet count was 15×10³ per cubic millimeter, the median duration of disease was 6.3 years, and patients had received a median of four different immune thrombocytopenia therapies previously. All the treatment-related adverse events were of grade 1 or 2 and transient. There were no treatment-related bleeding or thrombotic events of grade 2 or higher. At a median of 167.5 days (range, 4 to 293) of treatment, 24 of 60 patients (40%) overall and 18 of the 45 patients (40%) who had started rilzabrutinib treatment at the highest dose met the primary end point of platelet response. The median time to the first platelet count of at least 50×10³ per cubic millimeter was 11.5 days. Among patients with a primary platelet response, the mean percentage of weeks with a platelet count of at least 50×10³ per cubic millimeter was 65%.

CONCLUSIONS

Rilzabrutinib was active and associated with only low-level toxic effects at all dose levels. The dose of 400 mg twice daily was identified as the dose for further testing. Overall, rilzabrutinib showed a rapid and durable clinical activity that improved with length of treatment. (Funded by Sanofi; ClinicalTrials.gov number, NCT03395210; EudraCT number, 2017-004012-19.).

Bruton tyrosine kinase inhibitors as potential therapeutic agents for COVID-19: A review

Coronavirus disease 2019 (COVID-19) is first detected in December 2019 in Wuhan, China which is a new pandemic caused by SARS-COV-2 that has greatly affected the whole world. Bruton tyrosine kinase (BTK) inhibitors are drugs that are used for the management of cancer, and are being repurposed for COVID-19. BTK regulates macrophage and B cell activation, development, survival, and signaling. Inhibition of BTK has revealed an ameliorative effect on lung injury in patients with severe COVID-19. Thus, this review aimed to summarize evidence regarding the role of Bruton tyrosine kinase inhibitors against COVID-19. To include findings from diverse studies, publications related to BTK inhibitors and Covid-19 were searched from the databases such as SCOPUS, Web of Science, Medline, Google Scholar, PubMed, and Elsevier, using English key terms. Both experimental and clinical studies suggest that targeting excessive host inflammation with a BTK inhibitor is a potential therapeutic strategy in the treatment of patients with severe COVID-19. Currently, BTK inhibitors such as ibrutinib and acalabrutinib have shown a protective effect against pulmonary injury in a small series group of COVID-19 infected patients. Small molecule inhibitors like BTK inhibitors, targeting a wide range of pro-inflammatory singling pathways, may a key role in the management of COVID-19.

Ibrutinib in patients with atrial fibrillation - the challenge of thromboembolic prophylaxis

Ibrutinib is a novel drug used in haematological malignancies. Its use is associated with an increased risk of atrial fibrillation (AF), which, in turn, exposes patients to embolic risk, including stroke. Reducing this risk requires anticoagulant therapy which is a matter of concern in the context of the increased bleeding risk of patients with haematological malignancies. In this context the presence of thrombocytopenia related to haematological disorder, ibrutinib-anticoagulants and ibrutinib-platelets interactions contribute to the amplification of the problem. The correct assessment of the thrombosis vs. haemorrhage balance represents a significant challenge for the clinician. In this paper we discuss practical issues related to anticoagulation in patients treated with ibrutinib and incident AF.

Keeping a balance in chronic lymphocytic leukemia (CLL) patients taking ibrutinib: ibrutinib-associated adverse events and their management based on drug interactions

INTRODUCTION

Ibrutinib is a highly effective drug for patients with chronic lymphocytic leukemia (CLL), and is well tolerated even by older patients and those unfit to receive conventional immuno-chemotherapy.

AREAS COVERED

The occurrence of adverse events was revealed as a major cause of ibrutinib failure in the real-world. Ibrutinib-induced lymphocytosis carries the risk of an untimely interruption of therapy because it may be misinterpreted as disease progression. In addition, drug interactions can worsen ibrutinib-associated toxicities by increasing the plasma concentration of ibrutinib. In this review, we present a case of major hemorrhage and atrial fibrillation (AF) during ibrutinib use and summarize the adverse events associated with ibrutinib. Furthermore, the practical management of ibrutinib-associated toxicities was covered with reference to a drug interaction mechanism.

EXPERT OPINION

Clinicians should examine the prescribed drugs prior to ibrutinib initiation and carefully monitor toxicities while taking ibrutinib. A reduced dose of ibrutinib with the concurrent use of CYP3A inhibitors such as antifungal agents could be an attractive strategy to reduce toxicities and may confer financial benefits. Reducing unexpected toxicities is as significant as achieving treatment response in the era of life-long therapy with ibrutinib in patients with CLL.

The Use of Bruton's Tyrosine Kinase Inhibitors to Treat Allergic Disorders

Purpose of review

Studies show that inhibitors of Bruton’s tyrosine kinase (BTKis), currently FDA-approved for the treatment of B cell malignancies, can prevent IgE-mediated reactions through broad inhibition of the FcεRI signaling pathway in human mast cells and basophils. This review will summarize recent data supporting the use of these drugs as novel therapies in various allergic disorders.

Recent findings

Recent studies have shown that BTKis can prevent IgE-mediated degranulation and cytokine production in primary human mast cells and basophils. Two oral doses of the second-generation BTKi acalabrutinib can completely prevent moderate passive systemic anaphylaxis in humanized mice and even protect against death during severe anaphylaxis. Furthermore, two doses of ibrutinib can reduce or eliminate skin prick test responses to foods and aeroallergens in allergic subjects. BTKis in development also show efficacy in clinical trials for chronic urticaria. Unlike other therapies targeting IgE, such as omalizumab, BTKis appear to have rapid onset and transient effects, making them ideal candidates for intermittent use to prevent acute reactions such as IgE-mediated anaphylaxis.

Summary

These studies suggest that BTKis may be capable of preventing IgE-mediated anaphylaxis, paving the way for future trials in food allergy and urticaria.

Preclinical Efficacy and Anti-Inflammatory Mechanisms of Action of the Bruton Tyrosine Kinase Inhibitor Rilzabrutinib for Immune-Mediated Disease

Bruton tyrosine kinase (BTK) is expressed in B cells and innate immune cells, acting as an essential signaling element in multiple immune cell pathways. Selective BTK inhibition has the potential to target multiple immune-mediated disease pathways. Rilzabrutinib is an oral, reversible, covalent BTK inhibitor designed for immune-mediated diseases. We examined the pharmacodynamic profile of rilzabrutinib and its preclinical mechanisms of action. In addition to potent and selective BTK enzyme and cellular activity, rilzabrutinib inhibited activation and inflammatory activities of B cells and innate cells such as macrophages, basophils, mast cells, and neutrophils, without cell death (in human and rodent assay systems). Rilzabrutinib demonstrated dose-dependent improvement of clinical scores and joint pathology in a rat model of collagen-induced arthritis and demonstrated reductions in autoantibody-mediated FcγR signaling in vitro and in vivo, with blockade of rat Arthus reaction, kidney protection in mouse Ab-induced nephritis, and reduction in platelet loss in mouse immune thrombocytopenia. Additionally, rilzabrutinib inhibited IgE-mediated, FcεR-dependent immune mechanisms in human basophils and mast cell-dependent mouse models. In canines with naturally occurring pemphigus, rilzabrutinib treatment resulted in rapid clinical improvement demonstrated by anti-inflammatory effects visible within 2 wk and all animals proceeding to complete or substantial disease control. Rilzabrutinib is characterized by reversible covalent BTK binding, long BTK residence time with low systemic exposure, and multiple mechanistic and biological effects on immune cells. Rilzabrutinib's unique characteristics and promising efficacy and safety profile support clinical development of rilzabrutinib for a broad array of immune-mediated diseases.

Relevance of the Bruton Tyrosine Kinase as a Target for COVID-19 Therapy

The outbreak of the novel coronavirus disease 2019 (COVID-19) has emerged as one of the biggest global health threats worldwide. As of October 2020, more than 44 million confirmed cases and more than 1,160,000 deaths have been reported globally, and the toll is likely to be much higher before the pandemic is over. There are currently little therapeutic options available and new potential targets are intensively investigated. Recently, Bruton tyrosine kinase (BTK) has emerged as an interesting candidate. Elevated levels of BTK activity have been reported in blood monocytes from patients with severe COVID-19, compared with those from healthy volunteers. Importantly, various studies confirmed empirically that administration of BTK inhibitors (acalabrutinib and ibrutinib) decreased the duration of mechanical ventilation and mortality rate for hospitalized patients with severe COVID-19. Herein, we review the current information regarding the role of BTK in severe acute respiratory syndrome coronavirus 2 infections and the suitability of its inhibitors as drugs to treat COVID-19. The use of BTK inhibitors in the management of COVID-19 shows promise in reducing the severity of the immune response to the infection and thus mortality. However, BTK inhibition may be contributing in other ways to inhibit the effects of the virus and this will need to be carefully studied.

Cardiomyopathies and Arrhythmias Induced by Cancer Therapies

Cardiology and oncology are two fields dedicated to the study of various types of oncological and cardiac diseases, but when they collide, a new specialty is born, i.e., cardio-oncology. Continuous research on cancer therapy has brought into the clinic novel therapeutics that have significantly improved patient survival. However, these therapies have also been associated with adverse effects that can impede the proper management of oncological patients through the necessity of drug discontinuation due to life-threatening or long-term morbidity risks. Cardiovascular toxicity from oncological therapies is the main issue that needs to be solved. Proper knowledge, interpretation, and management of new drugs are key elements for developing the best therapeutic strategies for oncological patients. Upon continuous investigations, the profile of cardiotoxicity events has been enlarged with the inclusion of myocarditis upon administration of immune checkpoint inhibitors and cardiac dysfunction in the context of cytokine release syndrome with chimeric antigen receptor T cell therapy. Affinity enhanced and chimeric antigen receptor T cells have both been associated with hypotension, arrhythmia, and left ventricular dysfunction, typically in the setting of cytokine release syndrome. Therefore, the cardiologist must adhere to the progressing field of cancer therapy and become familiar with the adverse effects of novel drugs, and not only the ones of standard care, such as anthracycline, trastuzumab, and radiation therapy. The present review provides essential information summarized from the latest studies from cardiology, oncology, and hematology to bring together the three specialties and offers proper management options for oncological patients.

Adverse cardiac effects of cancer therapies: cardiotoxicity and arrhythmia

Remarkable progress has been made in the development of new therapies for cancer, dramatically changing the landscape of treatment approaches for several malignancies and continuing to increase patient survival. Accordingly, adverse effects of cancer therapies that interfere with the continuation of best-possible care, induce life-threatening risks or lead to long-term morbidity are gaining increasing importance. Cardiovascular toxic effects of cancer therapeutics and radiation therapy are the epitome of such concerns, and proper knowledge, interpretation and management are needed and have to be placed within the context of the overall care of individual patients with cancer. Furthermore, the cardiotoxicity spectrum has broadened to include myocarditis with immune checkpoint inhibitors and cardiac dysfunction in the setting of cytokine release syndrome with chimeric antigen receptor T cell therapy. An increase in the incidence of arrhythmias related to inflammation such as atrial fibrillation can also be expected, in addition to the broadening set of cancer therapeutics that can induce prolongation of the corrected QT interval. Therefore, cardiologists of today have to be familiar not only with the cardiotoxicity associated with traditional cancer therapies, such as anthracycline, trastuzumab or radiation therapy, but even more so with an ever-increasing repertoire of therapeutics. This Review provides this information, summarizing the latest developments at the juncture of cardiology, oncology and haematology.

Cardiovascular Toxicities Associated With Ibrutinib

BACKGROUND

Ibrutinib has revolutionized treatment for several B-cell malignancies. However, a recent clinical trial where ibrutinib was used in a front-line setting showed increased mortality during treatment compared with conventional chemotherapy. Cardiovascular toxicities were suspected as the culprit but not directly assessed in the study.

OBJECTIVES

The purpose of this study was to identify and characterize cardiovascular adverse drug reactions (CV-ADR) associated with ibrutinib.

METHODS

This study utilized VigiBase (International pharmacovigilance database) and performed a disproportionality analysis using reporting odds ratios (ROR) and information component (IC) to determine whether CV-ADR and CV-ADR deaths were associated with ibrutinib. IC compares observed and expected values to find associations between drugs and adverse drug reactions using disproportionate Bayesian-reporting; IC₀₂₅ (lower end of the IC 95% credibility interval) >0 is significant.

RESULTS

This study identified 303 ibrutinib-associated cardiovascular deaths. Ibrutinib was associated with higher reporting of supraventricular arrhythmias (SVAs) (ROR: 23.1; 95% confidence interval: 21.6 to 24.7; p < 0.0001; IC₀₂₅: 3.97), central nervous system (CNS) hemorrhagic events (ROR: 3.7; 95% confidence interval: 3.4 to 4.1; p < 0.0001; IC₀₂₅: 1.63), heart failure (ROR: 3.5; 95% confidence interval: 3.1 to 3.8; p < 0.0001; IC₀₂₅: 1.46), ventricular arrhythmias (ROR: 4.7; 95% confidence interval: 3.7 to 5.9; p < 0.0001; IC₀₂₅: 0.96), conduction disorders (ROR: 3.5; 95% confidence interval: 2.7 to 4.6; p < 0.0001; IC₀₂₅: 0.76), CNS ischemic events (ROR: 2.2; 95% confidence interval: 2.0 to 2.5; p < 0.0001; IC₀₂₅: 0.73), and hypertension (ROR: 1.7; 95% confidence interval: 1.5 to 1.9; p < 0.0001; IC₀₂₅: 0.4). CV-ADR often occurred early after ibrutinib administration. Importantly, CV-ADR were associated with fatalities that ranged from ∼10% (SVAs and ventricular arrhythmias) to ∼20% (CNS events, heart failure, and conduction disorders). Ibrutinib-associated SVA portends poor prognosis when CNS events occur concomitantly, with 28.8% deaths (15 of 52 cases).

CONCLUSIONS

Severe and occasionally fatal cardiac events occur in patients exposed to ibrutinib. These events should be considered in patient care and in clinical trial designs. (Evaluation of Reporting of Cardio-vascular Adverse Events With Antineoplastic and Immunomodulating Agents [EROCA]; NCT03530215).

Ibrutinib-Associated Cardiac Tamponade with Concurrent Antiplatelet Therapy

Ibrutinib is approved for the first-line treatment of chronic lymphocytic leukemia (CLL). A well-known side effect of ibrutinib therapy is increased bleeding risk, which ranges from mild mucocutaneous bleeding to rarely life-threatening hemorrhage. The increased bleeding tendency associated with ibrutinib is thought to be related to its effect on several platelet signaling pathways, which can be exacerbated in the setting of concurrent antiplatelet or anticoagulant therapy. We present an 82-year-old male with CLL on ibrutinib and concurrent antiplatelet therapy who developed cardiac tamponade due to a hemorrhagic pericardial effusion requiring emergent placement of a pericardial window. This case further highlights the risk of major bleeding in patients treated with ibrutinib and concurrent antiplatelet therapy.

Differences and similarities in the effects of ibrutinib and acalabrutinib on platelet functions

While efficient at treating B-cell malignancies, Bruton tyrosine kinase (BTK) inhibitors are consistently reported to increase the risk of bleeding. Analyzing platelet aggregation response to collagen in platelet-rich plasma allowed us to identify two groups in the healthy population characterized by low or high sensitivity to ibrutinib in vitro. Inhibition of drug efflux pumps induced a shift from ibrutinib low-sensitive platelets to high-sensitive ones. At a clinically relevant dose, acalabrutinib, a second-generation BTK inhibitor, did not affect maximal collagen-induced platelet aggregation in the ibrutinib low-sensitive group but did inhibit aggregation in a small fraction of the ibrutinib high-sensitive group. Consistently, acalabrutinib delayed aggregation, particularly in the ibrutinib high-sensitive group. In chronic lymphocytic leukemia patients, acalabrutinib inhibited maximal platelet aggregation only in the ibrutinib high-sensitive group. Acalabrutinib inhibited collagen-induced tyrosine-753 phosphorylation of phospholipase Cγ2 in both groups, but, in contrast to ibrutinib, did not affect Src-family kinases. Acalabrutinib affected thrombus growth under flow only in the ibrutinib high-sensitive group and potentiated the effect of cyclooxygenase and P2Y₁₂ receptor blockers in both groups. Since the better profile of acalabrutinib was observed mainly in the ibrutinib low-sensitive group, replacement therapy in patients may not systematically reduce the risk of bleeding.