Purpose: Trastuzumab treatment is associated with occurrence of cardiac toxicity, for which monitoring of the left ventricular ejection fraction (LVEF) is indicated. The performance of the currently used monitoring protocol as defined in the summary of product characteristics (SPC) is however unknown. The objective of this analysis was to develop a model-based framework for evaluation and optimization of cardiac monitoring strategies.
Methods: The model-based framework comprised a previously developed exposure-response model for trastuzumab induced changes in LVEF, and a protocol-execution model that allowed incorporation of treatment interventions as described by a monitoring protocol. Metrics for evaluation of toxicity, dose intensity and monitoring burden were defined to allow evaluation and optimization of cardiac monitoring protocols.
Results: The success of a protocol-defined dose reduction was improved from 40% for the SPC-based protocol, to 79% for a scoring-based protocol, thereby decreasing the observed severity of cardiotoxicity. Including adaptation based on risk-profile allowed reduction of the mean number of LVEF measurements by 19%.
Conclusions: This model-based evaluation approach enabled evaluation and optimization of cardiac monitoring protocols that would be difficult to evaluate in a clinical setting. This approach can potentially be applied for other drugs that use repeated evaluation of continuous biomarkers for toxicity.