Bruton's tyrosine kinase inhibition suppresses pathological retinal angiogenesis.

BACKGROUND AND PURPOSE: Pathological retinal angiogenesis is a typical manifestation of vision-threatening ocular diseases. Many patients exhibit poor response or resistance to anti-vascular endothelial growth factor (VEGF) agents. Bruton's tyrosine kinase (BTK) controls the proliferation and function of immune cells. Therefore, we examined the anti-inflammatory and anti-angiogenic effects of BTK inhibition on retinal angiogenesis. EXPERIMENTAL APPROACH: Retinal neovascularisation and vascular leakage in oxygen-induced retinopathy in C57/BL6J mice were assessed by whole-mount retinal immunofluorescence. PLX5622 was used to deplete microglia and Rag1-knockout mice were used to test the contribution of lymphocytes to the effects of BTK inhibition. The cytokines, activation markers, inflammatory and immune-regulatory activities of retinal microglia/macrophages were detected using qRT-PCR and immunofluorescence. NLRP3 was detected by western blotting, and the effects of BTK inhibition on the co-culture of microglia and human retinal microvascular endothelial cells (HRMECs) were examined. KEY RESULTS: BTK inhibition suppressed pathological angiogenesis and vascular leakage, and significantly reduced retinal inflammation, which involved microglia/macrophages but not lymphocytes. BTK inhibition increased anti-inflammatory factors and reduced pro-inflammatory cytokines that resulted from NLRP3 inflammasome activation. BTK inhibition suppressed the inflammatory activity of microglia/macrophages, and acted synergistically with anti-VEGF without retinal toxicity. Moreover, the supernatant of microglia incubated with BTK-inhibitor reduced the proliferation, tube formation and sprouting of HRMECs. CONCLUSION AND IMPLICATIONS: BTK inhibition suppressed retinal neovascularisation and vascular leakage by modulating the inflammatory activity of microglia and macrophages. Our study suggests BTK inhibition as a novel and promising approach for alleviating pathological retinal angiogenesis.

Successful Treatment of Monoclonal Immunotactoid Glomerulopathy Associated with Chronic Lymphocytic Leukemia Using Ibrutinib.

A 71-year-old woman developed nephrotic syndrome during 10-year follow-up for chronic lymphocytic leukemia. A renal biopsy sample analysis revealed IgG1-lambda-positive monoclonal immunotactoid glomerulopathy (mITG). The patient was treated with ibrutinib, a Bruton tyrosine kinase inhibitor, and complete renal remission was achieved after 24 months. ITG is a rare disease that is characterized by glomerular deposition. In particular, mITG, which presents immune deposits that exhibit light-chain restriction, is often associated with hematologic disorders. Most patients with mITG receive immunosuppressive therapy and/or chemotherapy; however, to our knowledge, there have been no reports of treatment with ibrutinib.

Upfront Management of Blastoid Variant Mantle Cell Lymphoma: Making the Case for 2nd/3rd-Generation Bruton Tyrosine Kinase Inhibitor-Based Therapies.

INTRODUCTION: Blastoid variant-mantle cell lymphoma (BV-MCL) represents an aggressive subset of patients with no established standard of care treatment approach. METHODS: We performed a retrospective analysis of the clinical characteristics and outcomes of 17 de novo BV-MCL patients treated at our institution between May 2009 and September 2023. In addition, we reviewed the literature supporting 2nd/3rd generation Bruton's Tyrosine-kinase (BTKi)-based therapies for upfront management. RESULTS: The complete response rate to frontline and salvage therapy was 66.7% and 25%, respectively. Two-year overall survival (OS) was low at 62.5% (95% CI, 34.7%-81.1%). Variables associated with higher OS included receipt of consolidative HSCT (p = 0.017), TP53-wild type (p = 0.031), intermediate- versus high-risk Mantle Cell Lymphoma Prognostic Index score (p = 0.026), and achieving complete response with induction therapy (p = 0.027). DISCUSSION: Treatment outcomes with chemo-immunotherapy in BV-MCL patients are poor, especially among TP53-mutated patients. Recent findings describing positive outcomes with novel BTKi-based therapies are encouraging and should be considered in this high-risk population.

Pre-existing cardiovascular disease is associated with an increased risk of cardiovascular events during Bruton tyrosine kinase inhibitor therapy.

The association between pre-existing cardiovascular disease (CVD) and the development of cardiovascular adverse events (CVAE) during Bruton tyrosine kinase inhibitor (BTKi) therapy is not well established. We compared the rate of CVAE, such as new onset or worsening atrial fibrillation (AF), supraventricular tachycardia, ventricular tachycardia, hypertension, myocardial infarction, and sudden cardiac death, between individuals with and without pre-existing CVD, during BTKi treatment. Secondary objectives were to compare the outcomes of patients treated with first generation BTKi versus second generation BTKi and characterize management decisions. A single-center retrospective review was conducted on patients treated with BTKi from 2013 to 2022 at Beth Israel Deaconess Medical Center. Adjusted logistic regression analyses were performed to evaluate the association between pre-existing CVD and CVAE. In this cohort, 11 out of 54 patients (20.4%) with pre-existing CVD developed CVAE, compared to 11 out of 135 patients (8.1%) without pre-existing CVD [age- and sex-adjusted OR 2.79; 95% CI (1.09, 7.25), P = .03]. Patients with pre-existing CVD had higher odds of developing new or worsening AF [age- and sex-adjusted OR 3.36; 95% CI (1.09, 10.71), P = .03]. Results remained robust after further adjustment of comorbidities, type of BTKi, and baseline medications. These results highlight the need for standardized approaches to prevent and promptly detect CVAE during BTKi treatment, particularly in patients with pre-existing CVD.

Case report: Bruton tyrosine kinase inhibitor as therapy for chronic lymphocytic leukemia infiltrating a kidney allograft.

The burden of chronic lymphocytic leukemia (CLL) in the prognosis of solid organ transplant (SOT) recipients seems non-negligible. Whether transplanting a patient with previous CLL is safe or what is the optimal monitoring and treatment management after transplantation is still unclear and only based on few case series and reports. Therefore, we aimed to contribute to this understanding by reporting the first documented case of a clinically significant CLL with biopsy-proven infiltration of the kidney allograft and its successful management with a Bruton tyrosine kinase inhibitor (BTKi). We then reviewed the related literature, with a focus on CLL and kidney transplantation. Our main message is that BTKi may represent a safe and effective intervention to prevent the hazardous patient and graft outcomes of CLL in SOT patients.

Impact of ibrutinib on inflammation in a mouse model of Graves' orbitopathy.

Introduction: Bruton's tyrosine kinase (BTK) and interleukin (IL)-2 Inducible T-cell Kinase (ITK) inhibitors have anti-inflammatory properties. We investigated the therapeutic effect of ibrutinib, an orally bioavailable BTK/ITK inhibitor, in a mouse model of Graves' orbitopathy (GO). Methods: Genetic immunization was performed through intramuscular administration of the recombinant plasmid, pCMV6-hTSHR cDNA, to 8-week-old female BALB/c mice. Serum levels of T3, T4, and thyroid-stimulating hormone receptor (TSHR) antibodies (TRAbs) were quantified using enzyme-linked immunosorbent assay. Histopathological changes in orbital tissues were examined using immunohistochemistry (IHC) staining for TSHR and various inflammatory markers. Following successful genetic immunization, ibrutinib was orally administered daily for 2 weeks in the GO model mice. After treatment, the mRNA and protein expression levels of BTK, ITK, IL-1ß, and IL-6 in orbital tissues were evaluated using real-time PCR and Western blotting. Results: In total, 20 mice were sacrificed to confirm successful genetic immunization. The GO mouse group exhibited significantly increased serum T3, T4, and TRAb levels. IHC revealed increased expression of TSHR, IL-1ß, IL-6, transforming growth factor-ß1, interferon-γ, CD40, CD4, BTK, and ITK in the GO mouse model. The orbital inflammation was significantly attenuated in ibrutinib-treated mice. The mRNA and protein expression levels of BTK, ITK, IL-1ß, and IL-6 in orbital tissue were lower in ibrutinib-treated GO mouse group compared to the phosphate-buffered saline-treated GO mouse group. Conclusion: The GO mouse model demonstrated enhanced BTK and ITK expression. Ibrutinib, a BTK/ITK inhibitor, suppressed the inflammatory cytokine production. These findings highlight the potential involvement of BTK/ITK in the inflammatory pathogenesis of GO, suggesting its role as a novel therapeutic target.

Bruton tyrosine kinase inhibitor monotherapy in B-cell lymphoma and risk of infection: A systematic review and meta-analysis of randomized controlled trials.

Bruton's tyrosine kinase (BTK) inhibitors are important therapeutic advances with promising efficacy outcomes in the treatment of patients with chronic lymphocytic leukemia and other B-cell lymphoma subtypes. However, the utility of BTK inhibitors can be limited by adverse events such as infections. In this systematic review and meta-analysis, we aim to determine the risk of various infections associated with BTK inhibitor monotherapy in B-cell lymphoma patients. A comprehensive search was conducted in MEDLINE/PubMed, Embase, and Web of Science databases from their inception until October 2023. ClinicalTrials.gov, bibliographies, and relevant conference abstracts were also searched for additional records. Randomized controlled trials that included any B-cell lymphoma patients treated with BTK inhibitor monotherapy and reported infection were included. Meta-analysis was performed to calculate risk ratio (RR) using a random-effects model in R Statistical Software, version 4.3.2. Of 3292 studies retrieved, we included 12 studies in this systematic review and meta-analysis. The median age of patients across the study arms ranged between 64 and 73 years. The overall pooled RR for any grade upper respiratory tract infections (URTI) associated with BTK inhibitor treatment was 1.55 (95% Confidence Interval (CI) 1.22-1.97). The RR of grade ≥3 URTI was reported in 14 out of 1046 patients, yielding an RR of 1.46 (95% CI 0.61-3.54), which was not statistically significant. The pooled RR of any grade pneumonia was 1.20 (95% CI 0.68-2.10) and grade ≥3 pneumonia was 1.12 (95% CI 0.67-1.85), both of which were not statistically significant. Patients with B-cell lymphoma who are undergoing BTK inhibitor monotherapy face an elevated risk of developing URTI. Clinicians prescribing BTK inhibitors should be aware of the potential infectious events that may occur. Close monitoring and the implementation of effective prophylactic measures are essential for managing these patients.

Acalabrutinib alone or in combination with rituximab for follicular lymphoma: An open-label study.

Acalabrutinib is a selective, second-generation Bruton tyrosine kinase inhibitor. In this open-label, parallel-group study, patients with relapsed/refractory (R/R) follicular lymphoma (FL) were randomised to either acalabrutinib monotherapy or acalabrutinib plus rituximab. An additional cohort of patients with treatment-naive (TN) FL received only the acalabrutinib-rituximab combination. Acalabrutinib-rituximab was well tolerated and active in R/R and TN FL; in the TN cohort the overall response rate was 92.3% with most remissions lasting over 4 years. Acalabrutinib monotherapy was also well tolerated and active in R/R FL. These results support further study of acalabrutinib alone and in combination with rituximab in FL.

Dysregulation of Toll-Like Receptor Signaling-Associated Gene Expression in X-Linked Agammaglobulinemia: Implications for Correlations Genotype-Phenotype and Disease Expression.

INTRODUCTION: In X-linked agammaglobulinemia (XLA), the diversity of BTK variants complicates the study of genotype-phenotype correlations. Since BTK negatively regulates toll-like receptors (TLRs), we investigated if distinct BTK mutation types selectively modulate TLR pathways, affecting disease expression. METHODS: Using reverse transcription-quantitative polymerase chain reaction, we quantified ten TLR signaling-related genes in XLA patients with missense (n = 3) and nonsense (n = 5) BTK mutations and healthy controls (n = 17). RESULTS: BTK, IRAK2, PIK3R4, REL, TFRC, and UBE2N were predominantly downregulated, while RIPK2, TLR3, TLR10, and TLR6 showed variable regulation. The missense XLA group exhibited significant downregulation of IRAK2, PIK3R4, REL, and TFRC and upregulation of TLR3 and/or TLR6. CONCLUSION: Hypo-expression of TLR3, TLR6, and TLR10 may increase susceptibility to infections, while hyper-expression might contribute to chronic inflammatory conditions like arthritis or inflammatory bowel disease. Our findings shed light on the important inflammatory component characteristic of some XLA patients, even under optimal therapeutic conditions.

The potential of Bruton's tyrosine kinase (BTK) inhibitors in the pharmacotherapeutic management of immune and dermatological disease.

INTRODUCTION: The review article explores the evolving role of Bruton's tyrosine kinase (BTK) inhibitors in immune-mediated dermatological conditions, addressing significant gaps in current treatment approaches. AREAS COVERED: The review comprehensively discusses the mechanisms of action of BTK inhibitors, including irreversible and reversible inhibitors. Clinical applications of BTK inhibitors in dermatological diseases such as pemphigus, chronic spontaneous urticaria (CSU), hidradenitis suppurativa (HS), systemic lupus erythematosus (SLE), and atopic dermatitis are explored, highlighting recent advancements and ongoing clinical trials. Potential advantages of BTK inhibitors over existing therapies and challenges in translating preclinical findings to clinical outcomes are discussed. EXPERT OPINION/COMMENTARY: BTK inhibitors represent a promising therapeutic avenue for immune-mediated dermatological conditions, offering oral administration, targeted pathway inhibition, and a favorable safety profile compared to biologic therapies. Ongoing research and clinical trials hold the potential to address unmet needs and reshape the therapeutic landscape in dermatology.

Our manuscript explores how a new class of medications called Bruton tyrosine kinase (BTK) inhibitors could revolutionize the treatment of skin conditions caused by the immune system. These conditions, like chronic spontaneous urticaria (CSU), pemphigus, and systemic lupus erythematosus (SLE), often lack effective treatments. BTK inhibitors work by targeting specific pathways in the immune system, offering hope for patients with these challenging conditions.We reviewed clinical trials and research studies to understand how BTK inhibitors could benefit patients. One significant advantage of BTK inhibitors is their ability to provide targeted therapy, meaning they can specifically block the faulty immune responses driving these conditions without affecting the entire immune system. This targeted approach could lead to fewer side effects compared to current treatments, such as corticosteroids or immunosuppressants, which can have widespread effects on the body.Overall, BTK inhibitors represent a promising new approach to treating immune-mediated skin conditions. With further research and development, they could offer safer and more effective alternatives to current treatments, improving the lives of patients worldwide.

Bruton tyrosine kinase inhibitor-related atrial fibrillation and its implications in the treatment of B-cell lymphoma.

Adverse events of atrial fibrillation (AF) have been commonly reported in lymphoma patients in treating Bruton's tyrosine kinase inhibitors (BTKi). The incidence rate of AF can vary depending on the specific types of BTKi and the patient population. Totally 45 published studies have revealed that the overall incidence rate of AF is 5% (95% CI 4%-7%). By performing a subtype single-rate analysis, the second-generation BTKi shows a lower AF incidence rate and lower cardiovascular toxicity. In the subtype single-rate analysis, we conclude the different AF incidence rates of Ibrutinib (10%, 95% CI 7%-13%), Acalabrutinib (4%, 95% CI 1%-6%), Orelabrutinib (0%, 95% CI 0%-1%), and Zanubrutinib (0%, 95% CI 0%-1%). The comprehensive analysis of AF inspires us to better predict and manage AF and other cardiovascular events in treating lymphoma. Meticulous evaluation, collaboration between cardiologists and hematologists, and discovery of new biomarkers are essential for its management.

Three-year cardiovascular and non-cardiovascular adverse events in patients with chronic lymphocytic leukemia or small cell lymphocytic lymphoma treated with Bruton tyrosine kinase inhibitors acalabrutinib or ibrutinib: a real-world analysis.

Bruton tyrosine kinase (BTK) inhibitors play an important role in targeted treatment of B-cell lymphoproliferative disorders. However, adverse events may limit the proper course of treatment in many patients. The purpose of this study is to compare the risk of cardiovascular and non-cardiovascular adverse events in patients with chronic lymphocytic leukemia (CLL) or small cell lymphocytic lymphoma (SLL) treated with the first-generation BTK inhibitor ibrutinib versus second-generation acalabrutinib, using real-world data from a collaborative multinational network. We used data from the network (TriNetX), which encompasses more than 100 healthcare organizations worldwide. We queried the database for patients aged ≥ 18 years with chronic lymphocytic leukemia or small-cell lymphomas treated with ibrutinib or acalabrutinib in the past ten years before the analysis. We used propensity score matching to balance the cohorts. The 3-year cumulative incidences and hazard ratios for the following outcomes were calculated: atrial flutter or fibrillation, other arrhythmias, heart failure, ischemic stroke or peripheral embolism, acute coronary syndrome, bleeding, and sepsis. We compared 2,107 patients in each group. Atrial fibrillation or flutter occurred in 150 (7.1%) patients with acalabrutinib and 310 (14.7%) patients with ibrutinib during the 3-year follow-up (hazard ratio, 0.68, 95% CI 0.55-0.84). New-onset hypertension occurred in 342 (16.3%) patients in the acalabrutinib group and 584 (27.7%) patients in the ibrutinib group (hazard ratio 0.81, 95% CI 0.66-0.98). Sepsis was diagnosed in 136 (6.5%) patients in the acalabrutinib group versus 239 (11.3%) patients in the ibrutinib group (hazard ratio 0.77, 95 CI 0.60-0.98). The two groups had no significant differences concerning the other adverse events. In a large retrospective cohort using real-world data from electronic medical registers, patients with CLL or SLL treated with acalabrutinib had a better cardiovascular and non-cardiovascular safety profile than those treated with ibrutinib, with lower risks of atrial flutter or fibrillation, new-onset arterial hypertension, and sepsis.

BTK inhibitors: moving the needle on the treatment of chronic lymphocytic leukemia.

INTRODUCTION: Bruton's tyrosine kinaseinhibitors (BTKis) changed the trajectory of upfront and relapsed/refractory chronic lymphocytic leukemia (CLL) treatment. However, BTKis are plagued by a spectrum of toxicities. Zanubrutinib was developed to circumvent challenges with prolonged tolerability by increasing BTK selectivity and maximizing efficacy through pharmacokinetic/pharmacodynamic optimization. However, with the availability of ibrutinib, acalabrutinib, and zanubrutinib, limited data exists to guide sequencing of BTKi therapy in the relapsed/refractory setting. AREAS COVERED: We review the first head-to-head trial (ALPINE) of zanubrutinib versus ibrutinib for the treatment of relapsed/refractory CLL and compare zanubrutinib's clinical efficacy and toxicities, including in patients with del(17p) and/or TP53 mutations to ibrutinib and acalabrutinib. EXPERT OPINION: Zanubrutinibrepresents one of the new standards of care for relapsed/refractory CLL based on superior progression-free survival and response rates over ibrutinib. Whilezanubrutinib is associated with fewer cardiac toxicities, similar rates of neutropenia and hypertension are noted. Ongoing studies are pushing the envelope, utilizing targeted drug combinations and minimal residual disease markers as well as receptor tyrosine kinase-like orphan receptor 1 inhibitors, chimeric antigen receptor T-cells, and novel BTK degraders. However, zanubrutinibrepresents a strong contender in the arsenal of treatment options for relapsed/refractory CLL.

Emerging Role of Functional Magnetic Resonance Spectroscopy (MRS) to Monitor Response to Kinase Inhibitors in Cancer.

Inhibitors of kinases involved in signaling and other intracellular pathways, have revolutionized cancer treatment by providing highly targeted and effective therapies. However, timely monitoring treatment response remains a considerable challenge since conventional methods such as assessing changes in tumor volume do not adequately capture early responses or resistance development, due to the predominantly cytostatic rather than cytotoxic effect of kinase inhibitors. Magnetic resonance spectroscopy (MRS) is a non-invasive imaging technique that can provide insights into cellular metabolism by detecting changes in metabolite concentrations. By measuring metabolite levels, MRS offers a means to assess treatment response in real-time, providing earlier indications of efficacy or resistance compared to conventional imaging modalities. Bruton's Tyrosine Kinase (BTK) is a critical enzyme involved in B-cell receptor signaling. BTK inhibitors have been approved for the treatment of Mantle Cell Lymphoma (MCL) and other B-cell malignancies. Recent studies involving genome-scale gene expression, metabolomic, and fluxomic analyses have demonstrated that ibrutinib, an index BTK inhibitor, profoundly affects the key metabolic pathways in MCL cells., including glycolysis, glutaminolysis, pentose shunt, TCA cycle and phospholipid metabolism. Importantly, the effects of ibrutinib on MCL cells directly and proportionately correlates with their sensitivity to the drug. Consequently, changes in specific metabolite concentrations detectable non-invasively by MRS such as lactate and alanine reflecting mostly the status of cellular glycolysis and glutaminolysis, respectively, have emerged as potential biomarkers for predicting response and resistance of MCL cells to BTK inhibition, both in vitro and in vivo. Preparations to validate the utility of these biomarkers in clinical setting are under way. These studies may pave the way to monitor therapeutic response to kinase inhibitors also in other types of cancer.

Aplastic anemia triggered by the Bruton tyrosine kinase inhibitor acalabrutinib in two patients with mantle cell lymphoma - A case report.

The use of Bruton's tyrosine kinase inhibitors (BTKi) is rapidly increasing for patients with mantle cell lymphoma (MCL). Side effects reported so far are usually manageable. However, here we present two cases of life-threatening aplastic anemia (AA) upon treatment with the BTKi acalabrutinib for MCL. The first patient died of neutropenic infection secondary to AA. The second patient was successfully treated with immunosuppressive treatment but the MCL relapsed shortly thereafter. AA is a potentially fatal complication that should be considered when patients present with pancytopenia during treatment with BTKi.

Targeting Bruton's tyrosine kinase (BTK) as a signaling pathway in immune-mediated diseases: from molecular mechanisms to leading treatments.

Bruton's tyrosine kinase (BTK), a nonreceptor tyrosine kinase, plays a remarkable role in the transmission and amplification of extracellular signals to intracellular signaling pathways. Various types of cells use the BTK pathway to communicate, including hematopoietic cells particularly B cells and T cells. The BTK pathway plays a role in controlling the proliferation, survival, and functions of B cells as well as other myeloid cells. First, second, and third-generation BTK inhibitors are currently being evaluated for the treatment of immune-mediated diseases in addition to B cell malignancies. In this article, the available evidence on the action mechanisms of BTK inhibitors is reviewed. Then, the most recent data obtained from preclinical studies and ongoing clinical trials for the treatment of autoimmune diseases, such as pemphigus vulgaris, pemphigus foliaceus, bullous pemphigoid, systemic lupus erythematosus, Sjögren's disease, rheumatoid arthritis, systemic sclerosis, multiple sclerosis, myasthenia gravis, and inflammatory diseases such as psoriasis, chronic spontaneous urticaria, atopic dermatitis, and asthma are discussed. In addition, adverse effects and complications associated with BTK inhibitors as well as factors predisposing patients to BTK inhibitors complications are discussed.

Evaluating pirtobrutinib for the treatment of relapsed or refractory mantle cell lymphoma.

INTRODUCTION: Mantle cell lymphoma (MCL) is an uncommon non-Hodgkin lymphoma that is generally considered incurable. Covalent BTK inhibitors (cBTKi) are the cornerstone of treatment for relapsed or refractory (R/R) MCL, but treatment options are limited and prognosis is poor after cBTKi failure. Pirtobrutinib is a non-covalent BTK inhibitor that has demonstrated excellent efficacy and safety and represents an important new treatment in the evolving treatment landscape of R/R MCL. AREAS COVERED: This review will provide an overview of the therapeutic landscape of R/R MCL, characteristics of pirtobrutinib, and efficacy and safety data of pirtobrutinib in R/R MCL from pivotal clinical trials. PubMed and major hematology conference proceedings were searched to identify relevant studies involving pirtobrutinib. EXPERT OPINION: For patients with R/R MCL that has progressed after treatment with cBTKi, pirtobrutinib is an important and efficacious treatment that confers favorable outcomes. In the post-cBTKi setting, when chimeric antigen receptor (CAR) T-cell therapy is not available or feasible, pirtobrutinib is the preferred treatment for R/R MCL. How to sequence or combine pirtobrutinib with CAR T-cell therapy and other available or emerging therapies requires further investigation. Future studies should also explore the role of pirtobrutinib in earlier lines of therapy for MCL.