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.