Commentary: tumor growth, patient survival, and the search for the optimal phase II efficacy endpoint.

Disclosure: Employment/leadership position: Chris H. Takimoto, Ortho Biotech Oncology Research & Development; Intellectual property rights/inventor/patent holder: None; Consultant/advisory role: None; Honoraria: None; Research funding: None; Ownership interest: None; Expert testimony: None; Other: None. The content of this article has been reviewed by independent peer reviewers to ensure that it is balanced, objective, and free from commercial bias. No financial relationships relevant to the content of this article have been disclosed by the author, planners, independent peer reviewers, or staff managers.