Clinical Endpoints
Objective Response Rate
Also known as: ORR, Response rate
Definition
Percentage of patients achieving complete or partial tumor shrinkage per RECIST criteria.
Detailed Explanation
ORR includes complete responses (CR - no detectable tumor) and partial responses (PR - ≥30% tumor shrinkage). Higher ORR suggests more active therapy but doesn't always correlate with survival benefit. Used for accelerated approval, especially in heavily pretreated populations. Disease control rate (ORR + stable disease) is also reported.