Risk factors for the development of atrial fibrillation on ibrutinib treatment

Use of new and emerging cancer drugs: what the cardiologist needs to know

The last decade has witnessed a paradigm shift in cancer therapy, from non-specific cytotoxic chemotherapies to agents targeting specific molecular mechanisms. Nonetheless, cardiovascular toxicity of cancer therapies remains an important concern. This is particularly relevant given the significant improvement in survival of solid and haematological cancers achieved in the last decades. Cardio-oncology is a subspecialty of medicine focusing on the identification and prevention of cancer therapy-related cardiovascular toxicity (CTR-CVT). This review will examine the new definition of CTR-CVT and guiding principles for baseline cardiovascular assessment and risk stratification before cancer therapy, providing take-home messages for non-specialized cardiologists.

Bruton's tyrosine kinase inhibitor-related cardiotoxicity: The quest for predictive biomarkers and improved risk stratification

Ibrutinib was the first Bruton's tyrosine kinase (BTK) inhibitor approved for the treatment of patients with chronic lymphocytic leukemia (CLL). While producing durable responses and prolonging survival, roughly 20-25% of patients experience dose limiting side effects, mostly consisting of cardiovascular toxicities like severe hypertension and atrial fibrillation. While clinical predictors of BTK inhibitor-related cardiotoxicity have been proposed and may aid in risk stratification, there is no routine risk model used in clinical practice today to identify patients at highest risk. A recent study investigating genetic predictors of ibrutinib-related cardiotoxicity found that single nucleotide polymorphisms in KCNQ1 and GATA4 were significantly associated with cardiotoxic events. If replicated in larger studies, these biomarkers may improve risk stratification in combination with clinical factors. A clinicogenomic risk model may aid in identifying patients at highest risk of developing BTK inhibitor-related cardiotoxicity in which further risk mitigation strategies may be explored.

Chronic Lymphocytic Leukemia: Management of Adverse Events in the Era of Targeted Agents

The treatment landscape for CLL has undergone a profound transformation with the advent of targeted agents (TAs) like Bruton's Tyrosine Kinase inhibitors (BTKis) and BCL-2 inhibitors (BCL-2is). These agents target crucial cellular pathways in CLL, offering superior efficacy over traditional chemo-immunotherapy, which has led to improved progression-free and overall survival rates. This advancement promises enhanced disease control and potentially normal life expectancy for many patients. However, the journey is not without challenges, as these TAs are associated with a range of adverse events (AEs) that can impact treatment efficacy and patient quality of life. This review focuses on detailing the various AEs related to TA management in CLL, evaluating their frequency and clinical impact. The aim is to present a comprehensive guide to the effective management of these AEs, ensuring optimal tolerability and efficacy of TAs. By reviewing the existing literature and consolidating findings, we provide insights into AE management, which is crucial for maximizing patient outcomes in CLL therapy.

Artificial Intelligence Electrocardiography to Predict Atrial Fibrillation in Patients With Chronic Lymphocytic Leukemia

Background

The use of an artificial intelligence electrocardiography (AI-ECG) algorithm has demonstrated its reliability in predicting the risk of atrial fibrillation (AF) within the general population.

Objectives

This study aimed to determine the effectiveness of the AI-ECG score in identifying patients with chronic lymphocytic leukemia (CLL) who are at high risk of developing AF.

Methods

We estimated the probability of AF based on AI-ECG among patients with CLL extracted from the Mayo Clinic CLL database. Additionally, we computed the Mayo Clinic CLL AF risk score and determined its ability to predict AF.

Results

Among 754 newly diagnosed patients with CLL, 71.4% were male (median age = 69 years). The median baseline AI-ECG score was 0.02 (range = 0-0.93), with a value ≥0.1 indicating high risk. Over a median follow-up of 5.8 years, the estimated 10-year cumulative risk of AF was 26.1%. Patients with an AI-ECG score of ≥0.1 had a significantly higher risk of AF (HR: 3.9; 95% CI: 2.6-5.7; P < 0.001). This heightened risk remained significant (HR: 2.5; 95% CI: 1.6-3.9; P < 0.001) even after adjusting for the Mayo CLL AF risk score, heart failure, chronic kidney disease, and CLL therapy. In a second cohort of CLL patients treated with a Bruton tyrosine kinase inhibitor (n = 220), a pretreatment AI-ECG score ≥0.1 showed a nonsignificant increase in the risk of AF (HR: 1.7; 95% CI: 0.8-3.6; P = 0.19).

Conclusions

An AI-ECG algorithm, in conjunction with the Mayo CLL AF risk score, can predict the risk of AF in patients with newly diagnosed CLL. Additional studies are needed to determine the role of AI-ECG in predicting AF risk in CLL patients treated with a Bruton tyrosine kinase inhibitor.

Real-world effectiveness and safety of ibrutinib in relapsed/refractory mantle cell lymphoma in Japan: post-marketing surveillance

Efficacy and safety data for ibrutinib in Japanese patients with relapsed/refractory (R/R) mantle cell lymphoma (MCL) were limited at the time of its approval in Japan. All-case post-marketing surveillance was conducted in Japanese R/R MCL patients who began ibrutinib treatment between December 2016 and December 2017, and patients were followed until 30 June 2020. In the effectiveness analysis set (n = 202), the overall response rate was 59.9%, 52-week progression-free survival was 47.5%, and overall survival was 69.3%. Safety was assessed in 248 patients (median age 74.0 years). When ibrutinib treatment was started, patients had received a median of three prior lines of therapy. The overall incidence of adverse events (AE) was 74.6%, and AE frequency and severity grade distribution were similar between patients with 1 versus more than 1 prior line of therapy. The most common AE was platelet count decreased (all grades; 10.4%), similarly to previous observations in patients with R/R chronic lymphocytic leukemia/small lymphocytic lymphoma. Five patients (2.0%) developed atrial fibrillation. The effectiveness and safety of ibrutinib were consistent with its known profile at approval in Japan. These results suggest that ibrutinib is effective and safe in Japanese R/R MCL patients in routine clinical practice.

The risk vs. benefit calculus of anticoagulation in patients with ibrutinib-related atrial fibrillation

For ibrutinib-related atrial fibrillation (IRAF), guidelines for anticoagulation do not exist. We sought to describe stroke, bleeding, and anticoagulation rates among patients with IRAF. We performed a single-center retrospective review of 168 patients treated with ibrutinib followed from 2013 to 2022. Over a median follow-up of 6.4 years, 44 (26.0%) patients developed IRAF of which 38 (86.4%) had a CHA2DS2-VASc ≥2 and 7 (15.9%) had a HAS-BLED ≥3. Anticoagulation was initiated in 20 (45.5%) without a clear pattern in scores, risk factors, or cumulative dose, besides having another reason for anticoagulation. Few patients with IRAF developed non-hemorrhagic CVA (n = 3, 6.8%) or significant bleeding (n = 3, 6.8%). Among those with each adverse outcome, 2 in each group were anticoagulated and all were older than 65 years old. In conclusion, decisions for anticoagulation vary widely and patients who are elderly or with HTN may be most at risk for CVA or significant bleed.

Incidence of cardiovascular and bleeding events and reasons for discontinuation in patients with chronic lymphocytic leukemia treated with ibrutinib-A retrospective analysis on consecutive patients from a well-defined region

OBJECTIVE

Ibrutinib treatment is associated with cardiovascular side effects, in particular atrial fibrillation (AF) and hypertension, as well as increased risk of bleeding. Here, we aimed at describing the incidence of these events during long-term follow-up in patients with chronic lymphocytic leukemia treated outside clinical trials as well as identifying clinical factors predictive of developing AF. Additionally, other reasons for treatment withdrawal were analyzed.

METHODS

The study was retrospective, data were collected from medical records.

RESULTS

A total of 134 patients were identified. Median follow-up was 32 months (range 3-103) and median duration of ibrutinib treatment was 26 months (range 1-103). Of 110 patients with no prior history of AF, 24.5% were diagnosed during treatment. Newly diagnosed or worsening of pre-existing hypertension occurred in 15.7%. Sixty-six % of the patients experienced bleeding events, of which 7.5% grade 3-4. Treatment discontinuation and dose reduction occurred in 68% and 47% of the patients, respectively, mostly due to toxicity.

CONCLUSIONS

The incidence of AF was high and at a median follow-up of 2.5 years, two-thirds of the patients discontinued treatment mostly due to bleeding and infections. Treatment-related toxicity of any grade should be regarded as a concern of prolonged ibrutinib therapy.

Risk of New-Onset Atrial Fibrillation Associated With Targeted Treatment of Lymphoma

Background

Lymphoma treatment may be associated with new-onset atrial fibrillation (AF), especially among patients treated with Bruton tyrosine kinase inhibitors (BTKi).

Objectives

The authors sought to assess the risk of new-onset AF, AF risk factors, and the impact of AF on mortality in patients with lymphoma and no history of AF.

Methods

The University of Rochester Medical Center Lymphoma Database was used to identify patients. The primary outcome was any AF episode identified using the International Classification of Diseases-10th Revision codes. Multivariable Cox regression was used to assess the risk of AF through the use of a time-dependent covariate for treatment overall as well as separate time-varying measures of BTKi (mainly ibrutinib) and non-BTKi treatment. The relative risk of all-cause mortality was determined using Cox proportional hazards analysis.

Results

Among 1,957 lymphoma patients, the rate of AF at 5-years following initiation of BTKi treatment was higher (25%) compared to those receiving non-BTKi therapy (8%), and those receiving no treatment (4%). Multivariable analysis showed that BTKi treatment was associated with pronounced increased risk for AF compared to no treatment (HR: 5.07 [95% CI: 2.88-8.90; P < 0.001]). Non-BTKi treatment was associated with an increased risk of AF compared to no treatment (HR: 1.82 [95% CI: 1.14-2.89; P = 0.012]). Risk factors for the development of AF included age ≥64 years, male sex, hypertension, and lymphoma treatment. New AF was associated with an increased risk for subsequent mortality (HR: 3.71 [95% CI: 2.59-5.31]).

Conclusions

Patients undergoing lymphoma treatment, especially those with high-risk features, may benefit from AF surveillance.

Cardiovascular Toxicities of BTK Inhibitors in Chronic Lymphocytic Leukemia: JACC: CardioOncology State-of-the-Art Review

Over the past decade, the treatment landscape of chronic lymphocytic leukemia (CLL) has dramatically changed, shifting from cytotoxic chemotherapy to targeted therapies. Bruton's tyrosine kinase (BTK) inhibitors have revolutionized the treatment of CLL and are increasingly applied in many other malignancies. However, ibrutinib, the first BTK inhibitor approved, is associated with serious toxicities, including atrial fibrillation in up to 38% of patients, ventricular arrhythmias, and other cardiovascular toxicities. Emerging data suggest several newer BTK inhibitors (eg, acalabrutinib, zanubrutinib) are still associated with cardiotoxic risks. This review examines the current state of evidence, including incidence rates, risk factors, mechanisms, and management strategies of cardiovascular toxicities with BTK inhibitors and other CLL therapies. We specifically focus on atrial fibrillation, ventricular arrhythmias/sudden death, hypertension, heart failure, bleeding, and stroke. We also touch on other emerging BTK therapies (eg, pirtobrutinib). Finally, we highlight key unanswered questions and future directions of research.

Cardiovascular Toxicity of Immune Checkpoint Inhibitors: A Guide for Clinicians

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment and care of patients with cancer owing to unique features, including the occurrence of the so-called immune-related adverse events (irAEs). A multidisciplinary team, possibly including a cardio-oncology specialist, is warranted to achieve a favorable patient outcome. Cardiovascular toxicity, especially myocarditis, emerged as a life-threatening irAE in the real-word setting, and the European Society of Cardiology has recently published the first guideline on cardio-oncology to increase awareness and promote a standardized approach to tackle this complex multimodal issue, including diagnostic challenges, assessment, treatment, and surveillance of patients with cancer receiving ICIs. In this article, through a question & answer format made up of case vignettes, we offer a clinically oriented overview on the latest advancements of ICI-related cardiovascular toxicity, focusing on myocarditis and associated irAEs (myositis and myasthenia gravis within the so-called overlap syndrome), with the purpose of assisting clinicians and healthcare professionals in daily clinical practice.

Predictors of ibrutinib-associated atrial fibrillation: 5-year follow-up of a prospective study

Ibrutinib-associated atrial fibrillation (IRAF) emerged among the adverse events of major interests in ibrutinib-treated patients as real-world studies showed a higher incidence compared to clinical trials. We prospectively analyzed predictors of IRAF in 43 single-center consecutive patients affected by chronic lymphocytic leukemia that started therapy with ibrutinib between 2015 and 2017. Key secondary endpoints were to describe the management of IRAF and survival outcomes. During a median follow-up period of 52 months, we registered 45 CV events, with a total of 23 AF events in 13 patients (CI 30.0% (95% CI: 16.5-43.9)). Pre-existent cardiovascular risk factors, in particular hypertension, a previous history of AF and a high Shanafelt risk score emerged as predictors of IRAF. Baseline echocardiographic evaluation of left atrial (LA) dimensions confirmed to predict IRAF occurrence and cut-off values were identified in our cohort: 32 mm for LA diameter and 18 cm2 for LA area. No difference in progression free survival and overall survival emerged in patients experiencing IRAF. Following AF, anticoagulation was started in all eligible patients, and cardioactive therapy was accordingly modified. Echocardiography represents a highly reproducible and widespread tool to be included in the work-up of ibrutinib candidates; the identification of IRAF predictors represents a useful guide to clinical practice.

Electrocardiographic Predictors of Atrial Fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common pathological arrhythmia, and its complications lead to significant morbidity and mortality. However, patients with AF can often go undetected, especially if they are asymptomatic or have a low burden of paroxysms. Identification of those at high risk of AF development may help refine screening and management strategies.

METHODS

PubMed and Embase databases were systematically searched for studies looking at electrocardiographic predictors of AF from inception to August 2021.

RESULTS

A total of 115 studies were reported which examined a combination of atrial and ventricular parameters that could be electrocardiographic predictors of AF. Atrial predictors include conduction parameters, such as the PR interval, p-wave index and dispersion, and partial interatrial or advanced interatrial block, or morphological parameters, such as p-wave axis, amplitude and terminal force. Ventricular predictors include abnormalities in QRS amplitude, morphology or duration, QT interval duration, r-wave progression and ST segment, i.e., t-wave abnormalities.

CONCLUSIONS

There has been significant interest in electrocardiographic prediction of AF, especially in populations at high risk of atrial AF, such as those with an embolic stroke of undetermined source. This review highlights the breadth of possible predictive parameters, and possible pathological bases for the predictive role of each parameter are proposed.

Bruton tyrosine kinase inhibitors in the management of Waldenström macroglobulinemia

Bruton tyrosine kinase (BTK) inhibitors have taken a central role in the management of patients with Waldenström macroglobulinemia and are the only agents approved by the Food and Drug Administration (FDA) to treat these patients. Although associated with high rates of durable responses, unmet needs with BTK inhibitor therapy include indefinite duration therapy, high cost, scarcity of complete responses, and lower rates and shorter duration of response in patients with CXCR4 mutations. Herein, we review the data supporting the use of covalent BTK inhibitors, selected management issues, clinical trials with covalent BTK inhibitor combination regimens, and up-and-coming non-covalent BTK inhibitors.

Efficacy and safety of ibrutinib in relapsed/refractory CLL and SLL in Japan: a post-marketing surveillance

Ibrutinib is approved in Japan for the treatment of chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) based on the results of global and domestic clinical studies. Following approval, we conducted an all-case post-marketing surveillance in Japanese patients with relapsed/refractory CLL/SLL newly initiated on ibrutinib treatment between May 2016−September 2017. Of the 323 patients enrolled, the safety and efficacy analysis sets comprised 289 and 205 patients, respectively. The overall response rate with ibrutinib treatment was 64.4%, and the estimated 52-week progression-free survival (PFS) and overall survival (OS) rates were 71.7 and 79.1%, respectively. No significant difference in the PFS rate was observed among patients with and without del(17p) (P = 0.160); however, PFS was significantly longer in patients who received 1 prior line of therapy versus >1 prior lines of therapy (P = 0.007). Adverse events occurred in 74.0% of patients, and typically occurred early (≤12 weeks) after ibrutinib initiation, followed by a decline in incidence thereafter. The overall rates of infection, bleeding, and arrhythmia were 22.5, 12.8, and 4.8%, respectively. Grade ≥3 bleeding events and atrial fibrillation occurred in 2.4% of patients each. The efficacy and safety profile of ibrutinib treatment in routine clinical practice was consistent with clinical trials and previously reported domestic data.

UMIN-CTR Clinical Trials Register ID: UMIN000021963.

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.

The Impact of Atrial Fibrillation on hospitalization Outcomes for Patients With Chronic Lymphocytic Leukemia Using the National Inpatient Sample Database

BACKGROUND

The incidence of atrial fibrillation (AF) in patients with chronic lymphocytic leukemia (CLL) has been on the rise. However, the excess burden added by AF to the morbidity and mortality of CLL patients especially in the hospitalized setting is undetermined.

METHODS

The National Inpatient Sample (NIS) database was accessed to gather data of hospitalized CLL patients with AF from 2009 to 2018. Propensity-score matching (PSM) and logistic regression model were performed to control for baseline patient factors to match 7265 CLL patient admissions with AF and 7265 CLL patient admissions without AF. The primary outcome was all-cause mortality (ACM), while the secondary outcomes included acute coronary syndrome (ACS), acute myocardial infarction (AMI), and the need for percutaneous coronary intervention (PCI), acute heart failure (AHF), acute hypoxic respiratory failure (AHRF), cardiac arrest (CA), cardiogenic shock (CS), stroke, and the total cost of hospitalization.

RESULTS

CLL patients with AF had a higher rate of ACM (6.06% vs 4.47%; odds ratio [OR] 1.39, 95% confidence interval [CI] 1.19-1.61; P =< .001). All other secondary outcomes including ACS, AMI, PCI, AHRF, CA, CS, and stroke were observed at a significantly higher rate in the AF group as well. The median total hospital cost was also higher in the AF group ($9097 vs. $7646; P value < .0001) CONCLUSION: CLL patients with AF are at a significantly increased risk of all-cause mortality, cardiac-related mortality, and stroke. For this population, a multidisciplinary approach should be orchestrated for better management and outcomes.

Utilizing left atrial strain to identify patients at risk for atrial fibrillation on ibrutinib

BACKGROUND

Ibrutinib is associated with atrial fibrillation (AF), though echocardiographic predictors of AF have not been studied in this population. We sought to determine whether left atrial (LA) strain on transthoracic echocardiography could identify patients at risk for developing ibrutinib-related atrial fibrillation (IRAF).

METHODS

We performed a retrospective review of 66 patients who had an echocardiogram prior to ibrutinib treatment. LA strain was measured with TOMTEC Imaging Systems, obtaining peak atrial longitudinal strain (PALS) and peak atrial contraction strain (PACS) on 4-chamber and 2-chamber views. Statistical analysis was performed with chi-square analysis, t test, or binomial regression analysis, with a P-value < .05 considered statistically significant.

RESULTS

Twenty-two patients developed IRAF (33%). Age at initiation of ibrutinib was significantly associated with IRAF (65.1 years vs 74.1 years, P = .002). Mean ibrutinib dose was lower among patients who developed IRAF (388.2 ± 121.7 vs 448.6 ± 88.4, P = .025). E/e' was significantly higher among patients who developed IRAF (11.5 vs 9.3, P = .04). PALS was significantly lower in patients who developed AF (30.3% vs 36.3%, P = .01). On multivariate regression analysis, age, PALS, and PACS were significantly associated with IRAF. On multivariate regression analysis, only PACS remained significantly associated with IRAF while accounting for age.

CONCLUSIONS

Age, ibrutinib dose, E/e', and PALS on pre-treatment echocardiogram were significantly associated with development of IRAF. On multivariate regression analyses, age, PALS, and PACS remained significantly associated with IRAF. Impaired LA mechanics add to the assessment of patients at risk for IRAF.

Chronic Lymphocytic Leukemia

Patients with chronic lymphocytic leukemia can be divided into three categories: those who are minimally affected by the problem, often never requiring therapy; those that initially follow an indolent course but subsequently progress and require therapy; and those that from the point of diagnosis exhibit an aggressive disease necessitating treatment. Likewise, such patients pass through three phases: development of the disease, diagnosis, and need for therapy. Finally, the leukemic clones of all patients appear to require continuous input from the exterior, most often through membrane receptors, to allow them to survive and grow. This review is presented according to the temporal course that the disease follows, focusing on those external influences from the tissue microenvironment (TME) that support the time lines as well as those internal influences that are inherited or develop as genetic and epigenetic changes occurring over the time line. Regarding the former, special emphasis is placed on the input provided via the B-cell receptor for antigen and the C-X-C-motif chemokine receptor-4 and the therapeutic agents that block these inputs. Regarding the latter, prominence is laid upon inherited susceptibility genes and the genetic and epigenetic abnormalities that lead to the developmental and progression of the disease.

Acalabrutinib monotherapy in patients with relapsed/refractory chronic lymphocytic leukemia: updated phase 2 results

Therapeutic targeting of Bruton tyrosine kinase (BTK) has dramatically improved survival outcomes for patients with chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). Acalabrutinib is an oral, highly selective BTK inhibitor that allows for twice-daily dosing due to its selectivity. In this phase 1b/2 study, 134 patients with relapsed/refractory CLL or SLL (median age, 66 years [range, 42-85 years]; median prior therapies, 2 [range, 1-13]) received acalabrutinib 100 mg twice daily for a median of 41 months (range, 0.2-58 months). Median trough BTK occupancy at steady state was 97%. Most adverse events (AEs) were mild or moderate, and were most commonly diarrhea (52%) and headache (51%). Grade ≥3 AEs (occurring in ≥5% of patients) were neutropenia (14%), pneumonia (11%), hypertension (7%), anemia (7%), and diarrhea (5%). Atrial fibrillation and major bleeding AEs (all grades) occurred in 7% and 5% of patients, respectively. Most patients (56%) remain on treatment; the primary reasons for discontinuation were progressive disease (21%) and AEs (11%). The overall response rate, including partial response with lymphocytosis, with acalabrutinib was 94%; responses were similar regardless of genomic features (presence of del(11)(q22.3), del(17)(p13.1), complex karyotype, or immunoglobulin variable region heavy chain mutation status). Median duration of response and progression-free survival (PFS) have not been reached; the estimated 45-month PFS was 62% (95% confidence interval, 51% to 71%). BTK mutation was detected in 6 of 9 patients (67%) at relapse. This updated and expanded study confirms the efficacy, durability of response, and long-term safety of acalabrutinib, justifying its further investigation in previously untreated and treated patients with CLL/SLL. This trial was registered at www.clinicaltrials.gov as #NCT02029443.

PDK1-AKT signaling pathway regulates the expression and function of cardiac hyperpolarization-activated cyclic nucleotide-modulated channels

AIM

The enzyme 3-phosphoinositide-dependent protein kinase-1 (PDK1) is associated with cardiac and pathological remodeling and ion channel function regulation. However, whether it regulates hyperpolarization-activated cyclic nucleotide-modulated channels (HCNs) remains unclear.

MAIN METHODS

In the atrial myocytes of heart-specific PDK1 "knockout" mouse model and neonatal mice, protein kinase B (AKT)-related inhibitors or agonists as well as knockdown or overexpression plasmids were used to study the relationship between PDK1 and HCNs.

KEY FINDINGS

HCN1 expression and AKT phosphorylation at the Thr308 site were significantly decreased in atrial myocytes after PDK1 knockout or inhibition; in contrast, HCN2 and HCN4 levels were significantly increased. Also, a similar trend of HCNs expression has been observed in cultured atrial myocytes after PDK1 inhibition, as further demonstrated via immunofluorescence and patch-clamp experiments. Moreover, these results of PDK1 overexpression indicate an opposite trend compared with the previous experimental results. However, the results of PDK1 inhibition or overexpression could be reversed by activating or inhibiting AKT, respectively.

SIGNIFICANCE

These results indicate that the PDK1-AKT signaling pathway is involved in the regulation of HCN mRNA transcription, protein expression, HCN current density, and cell membrane location.

Atrial fibrillation in patients with chronic lymphocytic leukemia (CLL) treated with ibrutinib: risk prediction, management, and clinical outcomes

BACKGROUND

Ibrutinib therapy is associated with an increased risk of atrial fibrillation (AF) in chronic lymphocytic leukemia (CLL). Risk assessment tools and outcomes of AF in these patients are not well described.

METHODS

We performed a retrospective review of patients with CLL treated with ibrutinib at Mayo Clinic between October 2012 and November 2018.

RESULTS

Two hundred ninety-eight patients were identified with a median time on ibrutinib of 19 months (range 0.23-69.7 months). Fifty-one patients developed treatment-emergent AF; the risk of treatment-emergent AF at 6 months, 1 year, and 2 years was 9%, 12%, and 16%, respectively. The following were associated with an increased risk of treatment-emergent AF on multivariable analyses: past history of AF (hazard ratio [HR] 3.5, p = 0.0072) and heart failure (HR 3.4, p = 0.0028). Most patients are able to continue ibrutinib therapy (dose reduced in 43%). Development of treatment-emergent AF was associated with shorter event-free survival (EFS; HR 2.0, p = 0.02) and shorter overall survival (OS; HR 3.2, p = 0.001), after adjusting for age, prior treatment status, TP53 disruption, heart failure, valvular disease, and past history of AF.

CONCLUSIONS

Patient comorbidities, rather than CLL-related factors, predict risk of treatment-emergent AF in patients treated with ibrutinib. Although the vast majority of patients with treatment-emergent AF are able to continue ibrutinib (with dose reduction in 43%), treatment-emergent AF appears to be associated with worse outcomes, independent of other adverse prognostic factors.