During the past decade, many high-alert medications have been developed and used in clinical practice. Particularly, in the pharmacotherapy of high-alert medications with large individual differences, more attention is needed. To achieve appropriate and individualized pharmacotherapy, there are many issues to be addressed from a clinical pharmacology perspective, such as enhanced monitoring and prior risk identification. This paper is focusing on the therapeutic drug monitoring of molecularly targeted anticancer drugs, and the provision of real-world evidence based on the clinical implementation of pharmacogenetic testing.