What is Milestone Survival in Clinical Trials?

Milestone survival rate is defined as the survival probability at a given point in time. It is classified as an endpoint related to Overall Survival (OS), however, it is considered a qualitative endpoint, describing a cross-sectional assessment at a specific time point, without considering all OS data. Milestone survival remains a potential alternative endpoint in late-stage drug development, similar to other endpoints used for assessing the progress in cancer immunology, and requires further validation.