Unveiling the Cardiotoxicity Conundrum: Navigating the Seas of Tyrosine Kinase Inhibitor Therapies

Background: Tyrosine kinase inhibitors (TKIs) have revolutionized the treatment of various solid and hematologic malignancies by targeting dysregulated signaling pathways critical for malignant cell growth. However, these therapeutic benefits are often accompanied by cardiotoxicities, such as hypertension, left ventricular dysfunction, QT prolongation, and tachyarrhythmias, among others. These cardiotoxicities post a significant challenge in clinical management, often limiting the use of otherwise effective therapies. The underlying mechanism of TKI-induced cardiotoxicity appears to be multifaceted, involving several pathways including: direct cardiomyocyte damage, mitochondrial dysfunction, endothelial damage, and disruption of signaling pathways critical for cardiac function. The range and severity of cardiotoxicities vary significantly across different TKIs, necessitating a comprehensive understanding of each agent's specific cardiovascular risk profile. Preventing and managing TKI-induced cardiotoxicity requires a comprehensive, multidisciplinary approach. Early identification of at-risk patients through baseline cardiovascular risk assessments and appropriate monitoring during therapy is crucial. Strategies to mitigate cardiotoxic effects include dose modification, the use of cardioprotective agents, and temporary discontinuation of therapy. Additionally, decision making via multidisciplinary teams ensures minimization of cardiovascular complications while also continuing effective cancer treatment. Historically, data have been limited regarding cardiotoxicity and most cancer therapies, which certainly includes TKIs. This review aims to synthesize the current body of knowledge on TKI-associated cardiotoxicities, while highlighting the importance of vigilance and proactive management to minimize cardiovascular complications.

Cardiotoxicity of Tyrosine Kinase Inhibitors in Philadelphia-Positive Leukemia Patients

In the past twenty years, tyrosine kinase inhibitors (TKIs) have substantially changed the therapeutic landscape and the clinical outcome of several cancers, including Philadelphia-chromosome positive chronic myeloid leukemia and acute lymphoblastic leukemia, chronic eosinophilic syndromes, gastrointestinal stromal tumors, and others. Despite the obvious advantages offered in terms of efficacy and the overall safety profile, this new class of agents presents novel side effects, sometimes different from those induced by conventional chemotherapy. Among others, the potential cardiac toxicity, characterized by possible arrhythmias and the highest rates of cardiac ischemic disease and heart failure, were predominantly investigated. In this article, the authors review the most significant evidence in this regard, highlighting the overall benefit of TKI usage and the need for careful monitoring, especially in elderly patients.

Cardiac Safety of Imatinib for the Treatment of COVID-19: A Secondary Analysis of a Randomized, Double-Blind, Placebo-Controlled Trial

ABSTRACT

Although previous studies support the clinical benefit of imatinib regarding respiratory status in hospitalized patients with COVID-19, potential cardiotoxicity may limit its clinical application. This study aimed to investigate the cardiac safety of imatinib in COVID-19. In the CounterCOVID study, 385 hospitalized hypoxemic patients with COVID-19 were randomly assigned to receive 10 days of oral imatinib or placebo in a 1:1 ratio. Patients with a corrected QT interval (QTc) >500 ms or left ventricular ejection fraction <40% were excluded. Severe cardiac adverse events were monitored for 28 days or until death occurred. Electrocardiogram measurements and cardiac biomarkers were assessed repeatedly during the first 10 days. A total of 36 severe cardiac events occurred, with a similar incidence in both treatment groups. No differences were observed in the computer-generated Bazett, manually interpreted Bazett, or Fridericia-interpreted QTcs. No clinically relevant alterations in other electrocardiogram parameters or plasma high-sensitivity cardiac troponin T (hs-cTnT) and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) concentrations were observed. Similar findings were observed in a subgroup of 72 patients admitted to the intensive care unit. In the univariate and multivariable linear mixed models, treatment with imatinib was not significantly associated with QT interval duration, hs-cTnT, or NT-proBNP levels. In conclusion, imatinib treatment did not result in more cardiac events, QT interval prolongation, or altered hs-cTnT or NT-proBNP levels. This suggests that treatment with imatinib is safe in hospitalized patients with COVID-19 with a QTc duration of less than 500 ms and left ventricular ejection fraction >40%.

Cardiotoxicity Induced by Protein Kinase Inhibitors in Patients with Cancer

Kinase inhibitors (KIs) represent a growing class of drugs directed at various protein kinases and used in the treatment of both solid tumors and hematologic malignancies. It is a heterogeneous group of compounds that are widely applied not only in different types of tumors but also in tumors that are positive for a specific predictive factor. This review summarizes common cardiotoxic effects of KIs, including hypertension, arrhythmias with bradycardia and QTc prolongation, and cardiomyopathy that can lead to heart failure, as well as less common effects such as fluid retention, ischemic heart disease, and elevated risk of thromboembolic events. The guidelines for cardiac monitoring and management of the most common cardiotoxic effects of protein KIs are discussed. Potential signaling pathways affected by KIs and likely contributing to cardiac damage are also described. Finally, the need for further research into the molecular mechanisms underlying the cardiovascular toxicity of these drugs is indicated.

Metastatic malignancies and the effect on arterial stiffness and blood pressure levels: the possible role of chemotherapy

BACKGROUND

The aim of the prospective study was to evaluate blood pressure (BP) and the arterial stiffness before and after chemotherapy in three subgroups of patients with metastatic colorectal, renal cell, and gastrointestinal carcinoma and exploit, if possible, the effect of chemotherapy and biological agents in the event of cardiotoxicity.

METHODS

A total of 171 patients were included in the study: 60 with kidney cancer, 18 with gastrointestinal stromal tumors (GISTs), and 93 with metastatic colorectal cancer. All patients were subjected to full clinical and laboratory evaluation before and after chemotherapy. Arterial-stiffness indices were assessed before the initiation and after the completion of chemotherapy by means of pulse wave velocity (PWV; Complior) and augmentation index (AIx; SphygmoCor).

RESULTS

Patients in all three cancer cohorts exhibited significantly (P<0.001) higher levels of carotid-radial PWV, carotid-femoral PWV, and AIx postchemotherapy, which remained significant after adjustment for BP and body-mass index. AIx exhibited greater change in the bowel-cancer cohort compared to the kidney and GIST cohorts (median 3.6, 1.75, and 1.4, respectively; P<0.001), which remained significant after adjustment for BP and body-mass index. Multiple regression analysis showed that patients with higher baseline systolic BP, diastolic BP, ejection fraction, and carotid-femoral PWV exhibited smaller differences postchemotherapy, while AIx75 baseline levels showed no difference postchemotherapy.

CONCLUSION

There is a clear burden in arterial stiffness in patients under chemotherapy for kidney, GIST, and metastatic colorectal cancer, irrespective of BP and other confounders.

Rapidly progressive dyspnea in gastrointestinal stromal tumor (GIST) with imatinib cardiac toxicity

Gastrointestinal stromal tumors (GISTs) are rare and current estimates range from 4,000 to 6,000 number of GIST cases in the USA annually. Imatinib, a tyrosine kinase inhibitor, has shown a survival benefit in GISTs, and the presence of KIT mutation status is predictive of response. The current case discusses rapidly progressive dyspnea and heart failure in an elderly male with metastatic GIST who was started on imatinib. Although reported as a rare and sporadic side effect of imatinib, the current case illustrates rapidity and the clinical significance of cardiotoxicity, with onset at 2 weeks.

Cases of imatinib-induced cardiotoxicity can range from being mild ventricular dysfunction to overt heart failure. Prior to starting imatinib, our patient had a history of hypertension. He subsequently ended up developing heart failure as acknowledged by the echocardiogram (ECHO). In general, elderly with preexisting cardiovascular comorbidity are at greater risk. The goal in such situations is immediate discontinuation or reduction of the imatinib dosage. The case prompts for awareness of imatinib cardiotoxicity. Moreover, a pretreatment cardiac assessment along with monitoring throughout therapy is therefore advisable. Also, imatinib-induced cardiotoxicity should be differentiated from imatinib-associated fluid retention, in which ECHO findings can be normal. This case report raises the concern for accelerated cardiotoxicity profile of imatinib. Further prospective studies with multidisciplinary input are needed to establish this association further.

Cardio-Oncology: Cancer Therapy-related Cardiovascular Complications in a Molecular Targeted Era: New Concepts and Perspectives

Cardio-oncology is a medical discipline that identifies, prevents, and treats the cardiovascular complications related to cancer therapy. Due to the remarkable proliferation of new cancer therapies causing cardiovascular complications, such as hypertension, heart failure, vascular complications, and cardiac arrhythmia, we provide an extensive, comprehensive revision of the most up-to-date scientific information available on the cardiovascular complications associated with the use of newer, novel chemotherapeutic agents, including their reported incidence, suggested pathophysiology, clinical manifestations, potential treatment, and prevention. The authors consider this topic to be relevant for the clinicians since cardiovascular complications associated with the administration of recently approved drugs are relatively underappreciated. The purpose of this article is to provide a state-of-the-art review of cardiovascular complications associated with the use of newer, novel chemotherapeutic agents and targeted therapies, including their reported incidence, suggested pathophysiology, clinical manifestations, potential treatment, and prevention.  Ongoing efforts are needed to provide a better understanding of the frequency, mechanisms of disease, prevention, and treatment of cardiovascular complications induced by the newer, novel chemotherapeutic agents. Development of a cardio-oncology discipline is warranted in order to promote task forces aimed at the creation of oncology patient-centered guidelines for the detection, prevention, and treatment of potential cardiovascular side effects associated with newer cancer therapies.

Sab mediates mitochondrial dysfunction involved in imatinib mesylate-induced cardiotoxicity

Imatinib mesylate is an effective treatment for chronic myelogenous leukemia and gastrointestinal stromal tumors. Although imatinib mesylate is highly tolerable, it has been implicated in severe congestive heart failure in mouse models and patients. A hallmark of imatinib mesylate-induced cardiotoxicity is mitochondrial dysfunction. The mitochondrial scaffold Sab has been implicated in facilitating signaling responsible for mitochondrial dysfunction in a c-Jun N-terminal Kinase (JNK)-dependent manner. We examined the impact of Sab-mediated signaling on imatinib mesylate cardiotoxicity in H9c2 rat cardiomyocyte-like cells. Silencing Sab increased the LD₅₀ of imatinib mesylate 4-fold in H9c2 cells. Disrupting Sab-mediated signaling prevented imatinib mesylate-induced apoptosis as well. Knockdown of Sab or inhibition with a small peptide prevented oxidative stress, which was indicated by decreased reactive oxygen species production, lipid peroxidation, and protein carbonylation. Further, inhibition of Sab-related signaling partially rescued deficits in mitochondrial respiration, ATP production, and membrane potential in imatinib mesylate-treated H9c2 cells. Conversely, over-expression of Sab in H9c2 cells increased the cardiotoxicity of imatinib mesylate in vitro decreasing the LD₅₀ over 4-fold. Sab expression was induced in H9c2 cells following cardiovascular-like stress in an AP-1 dependent manner. These data demonstrate that imatinib mesylate influences mitochondrial signaling leading to mitochondrial dysfunction and cardiotoxicity.

Cardiomyopathic Toxicity From Chemotherapy: Is There an Opportunity for Preemptive Intervention?

OPINION STATEMENT

The fight against cancer has never appeared more optimistic with multiple ongoing advances in cancer therapeutics; however, the prevention of cardiotoxicity from these treatments, both old and new, is a major focus of recent research. We recommend conceptualizing the prevention of cardiotoxicity as binary whereby primary prevention involves a uniform application of preventative efforts to anyone receiving a potentially cardiotoxic drug and secondary prevention directed towards those with left ventricular dysfunction, whether symptomatic or not. Recent studies suggest that cardioprotective medications such as renin-angiotensin inhibitors and beta blockers, among others, may be beneficial in the primary prevention of cardiotoxicity. Importantly, the magnitude of this protective effect appears to be driven by baseline risk of cardiac disease. In terms of secondary prevention, we recommend that patients with symptomatic heart failure related to cancer treatment should be treated as aggressively as patients with heart failure from other causes, as indicated by the most recent guidelines. We identify a relative paucity of data to guide those with asymptomatic left ventricular dysfunction. We summarize the literature to date with an emphasis on recent investigation and outline the importance of a continued partnership between cardiologists, oncologists, and primary care providers.

Prevention and Monitoring of Cardiac Dysfunction in Survivors of Adult Cancers: American Society of Clinical Oncology Clinical Practice Guideline

Purpose

Cardiac dysfunction is a serious adverse effect of certain cancer-directed therapies that can interfere with the efficacy of treatment, decrease quality of life, or impact the actual survival of the patient with cancer. The purpose of this effort was to develop recommendations for prevention and monitoring of cardiac dysfunction in survivors of adult-onset cancers.

Methods

Recommendations were developed by an expert panel with multidisciplinary representation using a systematic review (1996 to 2016) of meta-analyses, randomized clinical trials, observational studies, and clinical experience. Study quality was assessed using established methods, per study design. The guideline recommendations were crafted in part using the Guidelines Into Decision Support methodology.

Results

A total of 104 studies met eligibility criteria and compose the evidentiary basis for the recommendations. The strength of the recommendations in these guidelines is based on the quality, amount, and consistency of the evidence and the balance between benefits and harms.

Recommendations

It is important for health care providers to initiate the discussion regarding the potential for cardiac dysfunction in individuals in whom the risk is sufficiently high before beginning therapy. Certain higher risk populations of survivors of cancer may benefit from prevention and screening strategies implemented during cancer-directed therapies. Clinical suspicion for cardiac disease should be high and threshold for cardiac evaluation should be low in any survivor who has received potentially cardiotoxic therapy. For certain higher risk survivors of cancer, routine surveillance with cardiac imaging may be warranted after completion of cancer-directed therapy, so that appropriate interventions can be initiated to halt or even reverse the progression of cardiac dysfunction.

Discovery of N-(3-((1-Isonicotinoylpiperidin-4-yl)oxy)-4-methylphenyl)-3-(trifluoromethyl)benzamide (CHMFL-KIT-110) as a Selective, Potent, and Orally Available Type II c-KIT Kinase Inhibitor for Gastrointestinal Stromal Tumors (GISTs)

c-KIT kinase is a validated drug discovery target for gastrointestinal stromal tumors (GISTs). Clinically used c-KIT kinase inhibitors, i.e., Imatinib and Sunitinib, bear other important targets such as ABL or FLT3 kinases. Here we report our discovery of a more selective c-KIT inhibitor, compound 13 (CHMFL-KIT-110), which completely abolished ABL and FLT3 kinase activity. KinomeScan selectivity profiling (468 kinases) of 13 exhibited a high selectivity (S score (1) = 0.01). 13 displayed great antiproliferative efficacy against GISTs cell lines GIST-T1 and GIST-882 (GI50: 0.021 and 0.043 μM, respectively). In the cellular context, it effectively affected c-KIT-mediated signaling pathways and induced apoptosis as well as cell cycle arrest. In addition, 13 possessed acceptable bioavailability (36%) and effectively suppressed the tumor growth in GIST-T1 cell inoculated xenograft model without apparent toxicity. 13 currently is undergoing extensive preclinical evaluation and might be a potential drug candidate for GISTs.

Biomarkers as Predictors of Cardiac Toxicity From Targeted Cancer Therapies

BACKGROUND

Cardiac biomarkers have been extensively investigated as early detectors of cardiac toxicity from cancer therapies. Whereas the role of biomarkers in monitoring anthracycline toxicity is generally well understood, substantial uncertainty remains regarding their role in monitoring newer targeted cancer therapies.

METHODS AND RESULTS

This review article examines all major published studies using cardiac troponins and/or N-terminal pro-B-type natriuretic peptide (NT-proBNP) in monitoring for cardiac toxicity with trastuzumab, tyrosine kinase inhibitors, and mammalian target of rapamycin (mTOR) inhibitors. There is substantial variability among studies regarding biomarker assays used, sensitivity of the assays, and definitions of abnormal results. In general, troponin I predicts early but not late cardiac events when trastuzumab is administered after anthracyclines, but troponin increases likely reflect anthracycline injury rather than trastuzumab injury. NT-proBNP detects cardiac toxicity with tyrosine kinase inhibitors and mTOR inhibitors, but not independently from echocardiography.

CONCLUSIONS

Troponin I can serve as a marker for susceptibility to cardiac toxicity during early trastuzumab treatment in patients who have received recent anthracyclines. NT-proBNP can serve as a useful marker of cardiac toxicity in patients treated with tyrosine kinase inhibitors or mTOR inhibitors if echocardiographic screening is not being used.

Use of biomarkers for the assessment of chemotherapy-induced cardiac toxicity

OBJECTIVES

To review the evidence for the use of various biomarkers in the detection of chemotherapy associated cardiac damage.

DESIGN AND METHODS

Pubmed.gov was queried using the search words chemotherapy and cardiac biomarkers with the filters of past 10years, humans, and English language. An emphasis was placed on obtaining primary research articles looking at the utility of biomarkers for the detection of chemotherapy-mediated cardiac injury.

RESULTS

Biomarkers may help identify patients undergoing treatment who are at high risk for cardiotoxicity and may assist in identification of a low risk cohort that does not necessitate continued intensive screening. cTn assays are the best studied biomarkers in this context and may represent a promising and potentially valuable modality for detecting cardiac toxicity in patients undergoing chemotherapy. Monitoring cTnI levels may provide information regarding the development of cardiac toxicity before left ventricular dysfunction becomes apparent on echocardiography or via clinical symptoms. A host of other biomarkers have been evaluated for their utility in the field of chemotherapy related cardiac toxicity with intermittent success; further trials are necessary to determine what role they may end up playing for prediction and prognostication in this setting.

CONCLUSIONS

Biomarkers represent an exciting potential complement or replacement for echocardiographic monitoring of chemotherapy related cardiac toxicity which may allow for earlier realization of the degree of cardiac damage occurring during treatment, creating the opportunity for more timely modulation of therapy.

Imatinib-induced decompensated heart failure in an elderly patient with chronic myeloid leukemia: case report and literature review

Because it is safe and well tolerated, imatinib is a standard first-line therapy for chronic myeloid leukemia (CML). Although there have been sporadic reports of imatinib-induced cardiotoxicity, including left ventricle (LV) dysfunction and heart failure, the evidence for it is contradictory. Here, we reported a case of an 88-year-old male patient with CML developed decompensated heart failure following imatinib therapy. Four days after the initiation of imatinib, the patient developed orthopnea, edema and a pleural effusion accompanied by abdominal distension, nausea and vomiting. The chest X-ray film showed an enlarged cardiac profile. The echocardiogram demonstrated a decreased LV ejection fraction and enlarged left-side cardiac chambers. B-type natriuretic peptide concentrations were markedly increased. The patient recovered soon after the withdrawal of imatinib and introduction of comprehensive therapy for heart failure. Imatinib-induced cardiotoxicity in elderly patients is a potentially serious complication that merits further evaluation.

Detection and prevention of cardiac complications of cancer chemotherapy

Despite continuous improvements in management of patients with cancer, cardiac side-effects still account for a substantial limitation of chemotherapy. Evaluation of cardiac toxicity in patients includes consideration of biomarkers such as cardiac troponins and B-type natriuretic peptides, together with non-invasive imaging in the form of 2D-, 3D-, or strain-echocardiography, multiple gated radionuclide angiography, quantitative gated blood-pool SPECT, (123)I-metaiodobenzylguanidine scintigraphy, or cardiac magnetic resonance imaging. These approaches differ from each other with regards to availability, accuracy, sensitivity to detect early stages of cardiac injury, individual reliability, ease of use in a longitudinal follow-up perspective, and to related cost-effectiveness. Improving prevention of these cardiac side-effects depends on several, currently unresolved issues. Early detection and quantification of cardiac damage is required to adapt chemotherapy in progress for optimal management of patients. Whether increased availability of myocardial strain imaging and repeat blood biomarkers determinations will reliably and consistently achieve these goals remain to be confirmed. Also, protective approaches to reduce cardiac toxicity of anticancer drugs should be reconsidered according to the recently restricted approval for use of dexrazoxane. Anthracycline-based regimens, encapsulated anthracyclines and non-anthracycline regimens should be revisited with regards to antitumour efficacy and cardiac toxicity. Cardiovascular drugs that proved effective in prevention of anthracycline-induced cardiac toxicity in experimental models should be investigated in clinical trials. Finally, the efficacy of cardiovascular drugs that have already been tested in clinical settings should be confirmed and compared with each other in patients in increased numbers.

Evaluation of cardiac safety of lapatinib therapy for ErbB2-positive metastatic breast cancer: a single center experience

Lapatinib is a dual tyrosine kinase inhibitor (TKI) that has a considerable efficacy in ErbB2-positive metastatic breast cancer (MBC). Previous studies revealed that TKIs caused cardiotoxicity in approximately 10 % of the patients. This study assessed the cardiac safety of lapatinib in women with ErbB2-positive MBC. In this observational single center study, all patients with ErbB2-positive MBC who were previously treated with anthracycline, taxanes, and trastuzumab in the adjuvant and/or metastatic setting were assigned to receive lapatinib at a dose of 1,250 mg per day continuously plus capecitabine at a dose of 2,000 mg/m(2) in two divided doses on days 1 through 14 of a 21-day cycle. Cardiac toxicity was assessed with symptoms, transthoracic echocardiography, electrocardiography and biochemical markers (brain natriuretic peptide (BNP), creatine kinase (CK) and creatine kinase-MB) at baseline and every 9 weeks until disease progression. Twenty-six patients were treated with lapatinib and capecitabine therapy for a median of 18 (range 3-60) weeks. The median age was 48 (range 28-83) years. All patients had ErbB2-positive MBC. Among 25 eligible patients, 5 (19.2 %) patients experienced new cardiac events compared with baseline findings. Of these 5 patients, 1 (3.8 %) had T wave negativity, 1 (3.8 %) had sinus tachycardia, 1 (3.8 %) had grade 1 (453 ms) QT prolongation, and 2 (7.7 %) had decreased LVEF below the critical level. Among eligible 21 patients, 2 (7.7 %) had increased BNP, 1 (3.8 %) had increased CK, and 1 (3.8 %) had increased CK-MB level compared with baseline. No serious cardiac events that required monitorization or medication occurred. There was no statistically significant relationship between the duration of lapatinib administration and LVEF changes, QT prolongation, BNP, CK, and CK-MB level. According to our findings, lapatinib was safe and well tolerated and has a low incidence of cardiac side effects. Therefore, it seemed that cardiotoxicity was not a class effect of TKIs. However, despite the absence of clinically significant adverse cardiac effects under lapatinib therapy, the incidence of cardiotoxicity reported in our study was higher than previous lapatinib studies.

Clinical cardiac safety profile of nilotinib

BACKGROUND

Nilotinib is a second-generation tyrosine kinase inhibitor with significant efficacy as first- or second-line treatment in patients with chronic myeloid leukemia. Despite preclinical evidence indicating a risk of prolongation of the QT interval, which was confirmed in clinical trials, detailed information on nilotinib's cardiac safety profile is lacking.

DESIGN AND METHODS

Here, we retrospectively assessed cardiovascular risk factors in 81 patients who were being or had previously been treated with nilotinib therapy and evaluated cardiovascular parameters by longitudinal monitoring of the QT interval and left ventricular ejection fraction. Detailed information on the occurrence and management of defined cardiac adverse events was extracted.

RESULTS

The median duration of nilotinib therapy was 26 months (range, 1-72). The median QT interval at baseline was 413 msec (range, 368-499 msec). During follow-up, the median QT was not significantly different from the baseline value at any time-point. Sixteen of 81 patients (20%) had new electrocardiographic changes. Cardiac function, as assessed by measurement of left ventricular ejection fraction, did not change significantly from baseline at any time-point. During a median follow-up of 44 months (range, 2-73), seven patients (9%), all of whom had received prior imatinib therapy, developed 11 clinical cardiac adverse events requiring treatment. The median time from the start of nilotinib therapy to an event was 14.5 months (range, 2-68). Five of seven patients were able to continue nilotinib therapy with only one brief interruption.

CONCLUSIONS

Whereas new electrocardiographic abnormalities were recorded in 20% of all patients and some of them developed severe or even life-threatening coronary artery disease, QT prolongation, changes in left ventricular ejection fraction, and clinical cardiac adverse events were uncommon in patients treated with nilotinib.

A multifaceted evaluation of imatinib-induced cardiotoxicity in the rat

Cardiotoxicity was an unanticipated side effect elicited by the clinical use of imatinib (Imb). This toxicity has been examined in only a limited number of experimental studies. The present study sought, by a variety of approaches, to identify important characteristics of Imb-induced cardiac alterations. Male spontaneously hypertensive rats (SHRs) received oral doses of 10, 30, or 50 mg/kg Imb or water daily for 10 d. Cardiac lesions, detected at all doses, were characterized by cytoplasmic vacuolization and myofibrillar loss. In a second experiment, cardiac lesions were found in Sprague Dawley (SD) and SHR rats given 50 or 100 mg/kg Imb for 14 d. Mean cardiac lesion scores and serum levels of cardiac troponin I were higher in SHRs than in SD rats. Imb induced myocyte death by necrosis, autophagy, and apoptosis. Dose-related increases in cardiac expression were observed for several genes associated with endoplasmic reticulum stress response, protein folding, and vascular development and remodeling. Imb caused alterations in isolated myocytes (myofibrillar loss, highly disrupted and disorganized sarcomeric α-actinin, apoptosis, and increased lactate dehydrogenase release) at low concentrations (5 mM). The authors conclude that Imb exerts cardiotoxic effects that are manifest through a complex pattern of cellular alterations, the severity of which can be influenced by arterial blood pressure.

[New tyrosine kinase and EGFR inhibitors in cancer therapy. Cardiac and skin toxicity as relevant side effects. Part A: heart]

Cardiotoxicity is a serious side effect of targeted molecular therapies in cancer treatment. Monoclonal antibodies and tyrosine kinase inhibitors are known to be potent therapies in various neoplastic diseases due to inhibition of specific signal transduction pathways. Although targeted therapies are considered to be less toxic and better tolerated than common chemotherapies certain cardiac side effects have been observed. Cardiac toxicity may range from asymptomatic reduction of left ventricular function to life-threatening events like heart failure and acute coronary syndrome. Further side effects are arterial hypertension, thrombosis and arrhythmias. Cardiovascular side effects are common for anti-HER2 therapy in combination with anthracyclines and for inhibitors of angiogenesis. In these patients careful cardiac monitoring is warranted. Because of missing randomized long-term follow-ups, information about cardiac side effects is limited in newly developed targeted molecular therapies. In case of cardiac side effects or preexisting cardiac disease before therapy initiation, assessments by a cardiologist throughout the course of treatment are important. For patients with severe cardiac side effects, discontinuation of treatment is warranted; in case of asymptomatic cardiac side effects symptom-specific therapy should be performed.

Activity and side effects of imatinib in patients with gastrointestinal stromal tumors: data from a German multicenter trial

Gastrointestinal stromal tumors (GIST) are mesenchymal tumors that in the past were classified as leiomyosarcomas or leiomyomas not responding to standard sarcoma chemotherapy. In several phase I and II trials the efficacy and safety of imatinib was shown before the largest trial ever performed in a single sarcoma entity revealed response rates (CR/PR) of 52 %. This multicenter phase II trial presented here was performed to open access to imatinib for patients with unresectable or metastastatic GIST when the EORTC 62005 trial had been closed before imatinib was approved in Germany. It was designed to follow the best clinical response and to assess the efficacy, safety and tolerability of imatinib 400mg/d in patients with unresectable or metastatic gastrointestinal stromal tumor. - 95 patients were treated in this trial with Imatinib 400mg/d. Four patients (4.6 %) attained a complete response and 26 patients (29.9%) a partial response to imatinib treatment. Forty-one patients (47.1 %) revealed a stable disease and 16 patients (18.4 %) had a progressive disease. - Of the progressive patients 22% showed a partial response and 67 % showed stable disease after escalating the dose to 800 mg. According to SWOG tumor response classification, 66 patients (70%) were free of progression within the first year of treatment. - Seventy-one patients (74.7%) experienced adverse events or severe adverse events with a suspected relationship to the study drug. Among these, the most common were nausea (n=27 patients, 28.4 %), eyelid edema and peripheral edema in 23 patients each (24.2 %), diarrhea in 20 patients (21.1 %), muscle cramps in 15 patients (15.8 %) and fatigue in 13 patients (13.7 %). - Imatinib 400 mg/d led to disease stabilisation in 81,6% of patients with unresectable or metastatic malignant GIST. Thirty-four percent of patients attained a tumor remission (partial or complete response). The safety profile of imatinib based on adverse event assessment is favorable. Imatinib is generally well tolerated in patients with gastrointestinal stromal tumors.

Targeting non-malignant disorders with tyrosine kinase inhibitors

Receptor and non-receptor tyrosine kinases are involved in multiple proliferative signalling pathways. Imatinib, one of the first tyrosine kinase inhibitors (TKIs) to be approved, revolutionized the treatment of chronic myelogenous leukaemia, and other TKIs with different spectra of kinase inhibition are used to treat renal cell carcinoma, non-small-cell lung cancer and colon cancer. Studies also support the potential use of TKIs as anti-proliferative agents in non-malignant disorders such as cardiac hypertrophy, and in benign-proliferative disorders including pulmonary hypertension, lung fibrosis, rheumatoid disorders, atherosclerosis, in-stent restenosis and glomerulonephritis. In this Review, we provide an overview of the most recent developments--both experimental as well as clinical--regarding the therapeutic potential of TKIs in non-malignant disorders.

Principal long-term adverse effects of imatinib in patients with chronic myeloid leukemia in chronic phase

Imatinib mesylate (IM), an original Abl tyrosine kinase inhibitor, entered the clinics in 1998 for the treatment of patients with chronic myeloid leukemia (CML). The drug is universally considered the treatment of choice for most, if not all, patients with CML. Importantly, lessons learned from patients with CML have been applied successfully for the treatment of patients with other disorders where IM has since been found to be active by virtue of its ability to target other kinases, such as c-kit in patients with gastrointestinal stromal tumors. IM is associated with mild to moderate toxicity, mostly reversible by dose reduction or discontinuation of the drug. Most adverse effects occur within the first 2 years of starting therapy; however, late effects, many being unique, are now being recognized. In this report, we assess the toxicity associated with IM, with an emphasis on the long-term adverse effects.

The duration of the use of imatinib mesylate is only weakly related to elevated BNP levels in chronic myeloid leukaemia patients

Cardiotoxicity has been feared as a potential side effect of imatinib therapy. Studies with short-term follow-up failed to identify an excess of cardiac events, but longer-term observations are needed to more definitely exclude this adverse effect. This study was designed to assess the cardiac effects of imatinib in patients under long-term treatment. We included 90 chronic myeloid leukaemia (CML) patients under imatinib therapy for a median treatment time of 3.3 years (mean age 48.9 ± 15.1 years). Patients underwent clinical evaluation, electrocardiography, echocardiography (two-dimensional, colour flow, tissue Doppler and strain imaging), brain natiuretic peptide (BNP) and troponin I measurements. Twenty healthy volunteers were included as a control group for strain measurements. The mean ejection fraction was 68 ± 7% and the median BNP level was 9.6 pg/ml (interquartile range [IQR] 5.7-17.0 pg/ml). Two patients had either an elevated BNP or a depressed ejection fraction (2.2%; 90%CI 0.9-6.8%). Most of troponin I measurements were lower than the detection limit, except for two patients. Longitudinal strain was similar to measurements in healthy controls. A weak relation was observed between log BNP and imatinib treatment duration and dose. There was no relation between these variables and left ventricle ejection fraction. In conclusion, matinib-related cardiotoxicity is an uncommon event in CML patients, even during long-term treatment. Therefore, its use should not be cause of great concern, and the usefulness of regular cardiac monitoring all patients while on imatinib therapy is questionable.

Imatinib plus low-dose doxorubicin in patients with advanced gastrointestinal stromal tumors refractory to high-dose imatinib: a phase I-II study by the Spanish Group for Research on Sarcomas

BACKGROUND

In KIT-expressing Ewing sarcoma cell lines, the addition of doxorubicin to imatinib increases apoptosis, compared with imatinib or doxorubicin alone. On the basis of these in vitro data, the authors conducted a phase 1-2 trial of doxorubicin with imatinib in patients with gastrointestinal sarcoma tumors refractory to high-dose imatinib therapy.

METHODS

Patients with metastatic gastrointestinal sarcoma tumor resistant to imatinib at 400 mg by mouth (p.o.) twice a day were eligible for this multicenter study, and received imatinib (400 mg p.o. every day [q.d.]) concomitantly with doxorubicin 15-20 mg/m2/weekly for 4 cycles (monthly cycles), followed by imatinib (400 mg p.o. q.d.) maintenance in nonprogressive patients. Spiral computed tomography and positron emission tomography with F18-fluorodeoxyglucose were done basally and after 2 months of therapy to evaluate response. An in vitro study assessed the effect of combining imatinib and doxorubicin.

RESULTS

Twenty-six patients with progressive gastrointestinal sarcoma tumor were entered in the study. Treatment was well tolerated. Three (14%) of 22 evaluable patients had partial responses per Response Evaluation Criteria in Solid Tumors, and 8 (36%) had clinical benefit (partial response or stable disease for >or=6 months). Median progression-free survival (PFS) was 100 days (95% confidence interval [CI], 62-138), and median survival was 390 days (95% CI, 264-516). Interestingly, PFS was 211 days (95% CI, 52-370) in patients with wild type (WT) KIT and 82 days (95% CI, 53-111) in non-WT patients (10 mutant, 6 not assessed). A synergistic effect on cell line proliferation and apoptosis was found with imatinib and doxorubicin combination.

CONCLUSIONS

Low-dose chemobiotherapy combination showed promising activity in heavily pretreated gastrointestinal sarcoma tumor patients, especially in those with WT-KIT genotype.

The use of imatinib mesylate has no adverse effects on the heart function. Results of a pilot study in patients with chronic myeloid leukemia

To investigate cardiac effects of imatinib at an extended follow-up (median 12.4 months), 12 chronic myeloid leukemia patients underwent cardiac screening. No significant changes on the frequency of cardiovascular signs and symptoms, electrocardiographic abnormalities, echocardiographic measurements and BNP levels were observed. Median ejection fraction was 67% at baseline versus 68% at follow-up (median intra-patient change 0.5%). Median BNP levels were 8.3 versus 7.3pg/mL (median intra-patient change 0.2pg/mL). Troponin I measures were below the lower limit of detection, whereas strain measures were similar to healthy control. This pilot study suggests that it is probably safe to perform cardiac monitoring on an annual basis.

Practical management of tyrosine kinase inhibitor-associated side effects in GIST

Patients diagnosed with advanced gastrointestinal stromal tumor (GIST) are currently treated with oral tyrosine kinase inhibitors (TKIs). Imatinib mesylate is the standard first-line treatment, and sunitinib malate is administered second-line for patients who are intolerant or progress on imatinib. Imatinib has recently been approved for adjuvant treatment of GIST patients who have a significant risk for relapse. In both the metastatic and adjuvant settings, patients may be on these TKIs for many years. Low plasma imatinib levels have been reported to be associated with a short median time to progression of advanced GIST, stressing the importance of maintaining optimal drug levels. We summarize management of the most frequent and clinically significant adverse effects of imatinib and sunitinib in the treatment of GIST in the context of current guidelines, published literature, and the experience of three large GIST referral centers. The adverse events reviewed include nausea and vomiting, diarrhea, skin rash, musculoskeletal complaints, fatigue, hemorrhage, edema, hand-foot skin reaction, skin and hair discoloration, mucositis, hypertension, cardiac toxicity, hypothyroidism, liver transaminase changes, and hematological toxicity of imatinib and sunitinib. Potential drug-drug interactions with each respective agent are also discussed. With prudent use of supportive care measures, many side effects can be managed without dose reduction or interruption of treatment. On the other hand, individualized tailoring of the dose is often required to manage severe toxicity, such as painful hand-foot skin reactions, fatigue, hepatotoxicity, or cardiac toxicity. Management of many TKI-related adverse effects require further evaluation in prospective clinical trials.

Targeted therapies in the treatment of GIST: Adverse events and maximising the benefits of sunitinib through proactive therapy management

BACKGROUND AND OBJECTIVES

The introduction of targeted therapies has led to improved clinical outcomes in patients with unresectable gastrointestinal stromal tumours (GIST). The receptor tyrosine kinase (RTK) inhibitor imatinib mesylate has been approved as the first-line choice of therapy for this group of patients, while the RTK inhibitor, sunitinib malate, has been approved for the treatment of GIST after disease progression or intolerance to imatinib. Here we discuss and compare the tolerability profiles of imatinib and sunitinib based on published clinical trial data. We also review available data on the potential mechanisms by which these agents may cause adverse events (AEs) and we propose some general strategies to help clinicians to optimise treatment benefit with these agents.

FINDINGS

While the toxicity profiles of imatinib and sunitinib are well known, the mechanisms of toxicity of these agents have yet to be elucidated fully. Clinical observations along with retrospective and prospective analyses suggest that some RTK inhibitor-related AEs have a higher incidence than previously reported from clinical trials. In addition, with greater use, new and unexpected AEs are emerging. Clinicians need to be familiar with the toxicity profiles of RTK inhibitors as well as individual patient risk factors in order to optimise treatment benefit.

CONCLUSIONS

Imatinib and sunitinib are generally well tolerated with known and manageable AE profiles. Proactive therapy management strategies can enable treatment optimisation and allow patients to continue treatment with minimal interruption.

Rare incidence of congestive heart failure in gastrointestinal stromal tumor and other sarcoma patients receiving imatinib mesylate

BACKGROUND

The authors sought to determine the incidence and severity of cardiovascular toxicity caused by imatinib mesylate in gastrointestinal stromal tumor (GIST) and other sarcoma patients, and to explore cardiotoxicity caused by imatinib mesylate using cell culture and in vitro models.

METHODS

To determine the incidence and significance of serious cardiac adverse events in GIST and other sarcoma patients receiving imatinib mesylate, the authors performed a retrospective analysis of 219 consecutive patients treated with imatinib mesylate. In vitro studies of imatinib mesylate on cultured cardiomyocytes and biochemical studies of cardiac lysates from mice treated with imatinib mesylate were performed to define the potential cardiotoxic effects of imatinib mesylate.

RESULTS

Grade 3 or 4 potentially cardiotoxic adverse events (mostly edema or effusions) occurred in 8.2% of patients, were manageable with medical therapy, and infrequently required dose reduction or discontinuation of imatinib mesylate. Arrhythmias, acute coronary syndromes, or heart failure were uncommon, occurring in <1% of treated patients. However, administration of imatinib in a mouse model system resulted in inhibition of activation of protein kinases that are known to be important in the cardiac stress response.

CONCLUSIONS

The authors concluded that imatinib is an uncommon cause of cardiotoxicity, and that the cardiovascular adverse events that occur are manageable when recognized and treated. Nevertheless, our preclinical findings suggest that imatinib remains a potential cardiotoxin. Furthermore, the cardiac consequences of long-term imatinib therapy remain unknown. We therefore recommend treatment of risk factors for cardiovascular disease in imatinib-treated patients in accord with the American Heart Association guidelines for the prevention and treatment of heart failure.

Cardiotoxicity induced by tyrosine kinase inhibitors

BACKGROUND

Cardiotoxicity is a serious side effect of drugs used to treat cancer patients. Older chemotherapy drugs such as the anthracyclins and new targeted therapies, mainly trastuzumab, have been implicated in causing clinically significant cardiac dysfunction, which may be irreversible for many patients. The advent of a new category of drugs, the tyrosine kinase inhibitors has revolutionized the treatment of chronic myeloid leukemia, gastrointestinal stromal tumors and renal cancer, while their indications include a variety of other types of tumors.

METHODS

Assessment of the incidence and severity of cardiac toxicity caused by the tyrosine kinase inhibitors and discussion on the molecular mechanisms and mode of diagnosis based on recent clinical trials. Review of related literature.

RESULTS

Cardiac toxicity can be caused by the tyrosine kinase inhibitors imatinib mesylate, dasatinib, nilotinib, sunitinib, sorafenib and lapatinib, while gefitinib and erlotinib have not been related to toxic effect on the heart. Although targeted therapies are considered less toxic and better tolerated by patients compared with classic chemotherapy drugs, certain complications can be very serious and as these agents have been in use for a limited period of time, the exact profile of side effects will be better defined in the years to come. Cardiac toxicity may range from asymptomatic subclinical abnormalities such as electrocardiographic changes and left ventricular ejection fraction decline to life threatening events like congestive heart failure and acute coronary syndromes. For patients with severe side effects, discontinuation of treatment is warranted.

CONCLUSIONS

Careful cardiac monitoring and assessment by a cardiologist throughout the course of treatment with those TKIs that exert cardiac toxic effect is of primary importance.

Cardiovascular effects of tyrosine kinase inhibitors used for gastrointestinal stromal tumors

Small-molecule tyrosine kinase inhibitors (TKIs) have revolutionized the targeted treatment of various cancers, including gastrointestinal stromal tumors (GISTs). Recent evidence suggests the possibility of cardiotoxicity secondary to TKI treatment of GISTs. Preclinical studies indicate that imatinib and sunitinib may be directly toxic to cardiac myocytes. Clinically, cardiotoxicity attributable to imatinib seems to be infrequent and manageable, whereas that attributable to sunitinib is more common and more severe. Further prospective studies with objective cardiac monitoring and long-term follow up are needed to define more accurately the incidence, natural history, and risk factors for developing cardiotoxicity associated with TKIs used in the treatment of patients who have GISTs. In this review, the authors discuss what is known regarding the cardiovascular effects of TKIs used in the treatment of GISTs.