Incidence and Risk of QTc Interval Prolongation among Cancer Patients Treated with Vandetanib: A Systematic Review and Meta-analysis

Vandetanib is a multikinase inhibitor that is under assessment for the treatment of various cancers. QTc interval prolongation is one of the major adverse effects of this drug, but the reported incidence varies substantially among clinical trials. We performed a systematic review and meta-analysis to obtain a better understanding in the risk of QTc interval prolongation among cancer patients administered vandetanib.Eligible studies were phase II and III prospective clinical trials that involved cancer patients who were prescribed vandetanib 300 mg/d and that included data on QTc interval prolongation. The overall incidence and risk of QTc interval prolongation were calculated using random-effects or fixed-effects models, depending on the heterogeneity of the included studies. Nine trials with 2,188 patients were included for the meta-analysis. The overall incidence of all-grade and high-grade QTc interval prolongation was 16.4% (95% CI, 8.1-30.4%) and 3.7% (8.1-30.4%), respectively, among non-thyroid cancer patients, and 18.0% (10.7-28.6%) and 12.0% (4.5-28.0%), respectively, among thyroid cancer patients. Patients with thyroid cancer who had longer treatment duration also had a higher incidence of high-grade events, with a relative risk of 3.24 (1.57-6.71), than patients who had non-thyroid cancer. Vandetanib was associated with a significantly increased risk of all-grade QTc interval prolongation with overall Peto odds ratios of 7.26 (4.36-12.09) and 5.70 (3.09-10.53) among patients with non-thyroid cancer and thyroid cancer, respectively, compared to the controls.Treatment with vandetanib is associated with a significant increase in the overall incidence and risk of QTc interval prolongation. Different cancer types and treatment durations may affect the risk of developing high-grade QTc interval prolongation

Cardiovascular safety of second-generation anthistamines

Reports of serious cardiac arrhythmia associated with some second-generation antihistamines have prompted concern for their prescription. This article reviews the nature of the adverse events reported and concludes that the blockade of potassium channels, particularly the subtype responsible for the rapid component of the delayed rectifier current (IKr), is largely responsible for such adverse cardiac events. Consequently, antihistamines with little or no interaction with these channels are expected to have the greatest safety margin. The main cardiac arrhythmia of concern is that of torsades de pointes, a potentially fatal phenomenon characterized by prolonged ventricular depolarization that manifests as a prolonged QT interval and polymorphic ventricular tachycardia, with twisting of the QRS complexes. Based on pre-clinical and clinical evidence, it appears that loratadine, cetirizine, and fexofenadine are safe from cardiac arrhythmia via the IKr channel, whereas astemizole and terfenadine have a propensity to cause ventricular tachyarrhythmias

Safety biomarkers and the clinical development of oncology therapeutics: Considerations for cardiovascular safety and risk management

During the clinical development of oncology therapeutics, new safety biomarkers are being employed with broad applications and implications for risk management and regulatory approval. Clinical laboratory results, used as safety biomarkers, can influence decision making at many levels during the clinical development and regulatory review of investigational cancer therapies, including (1) initial eligibility for protocol therapy; (2) analyses used to estimate and characterize the safety profile; and (3) treatment delivery, based on specific rules to modify or discontinue protocol treatment. With the increasing applications of safety biomarkers in clinical studies, consideration must be given to possible unintended consequences, including (1) restricted access to promising treatments; (2) delays in study completion; and (3) limitations to dose delivery, escalation, and determination of the maximal tolerated dose, the recommended phase 2 dose, and the optimal biologic dose selected for registration studies. This review will compare and contrast 2 biomarkers for cardiac safety that are employed in an increasing number of clinical programs designed for investigational oncology therapeutics: (1) assessment of left ventricular ejection fraction by either echocardiography or multigated acquisition scan; and (2) electrophysiological measurement of QT/QTc duration, assessed by electrocardiogram, for predicting risk of a potentially fatal arrhythmia called torsades de pointes. While these and other new safety biomarkers have major value in the development of oncology therapeutics, their applications require careful consideration to avoid unintended consequences that could negatively affect (1) the care of patients with advanced malignancy and (2) the advancement of promising new agents