This article discusses the role of pharmacometrics and systems pharmacology in optimizing drug doses in oncology. The themed issue focuses on dose optimization in oncology due to the renewed interest in oncology dose selection and optimization triggered by the Project Optimus initiative by the US FDA. The articles in the issue cover various topics, including traditional quantitative clinical pharmacology applications, newer modeling and simulation methodologies, and model-informed drug development strategies. The goal is to provide insights into how pharmacometrics and systems pharmacology can facilitate dose optimization in oncology. [Extracted from the article]