ORR

Also known as: Objective Response Rate

The proportion of patients with a complete or partial tumour response.

Definition

Objective Response Rate (ORR) is the proportion of patients whose tumour shrinks by at least 30% (partial response) or disappears entirely (complete response), measured by RECIST 1.1 or comparable criteria. ORR is the fastest oncology readout — often supports accelerated approval — but is less robust than OS or PFS.

See also

• OS — Time from treatment start (or randomisation) until death from any cause.
• PFS — Time from treatment start until disease progression or death.
• RECIST — The standardised criteria for measuring tumour response on imaging in solid-tumour oncology trials.

Other clinical terms

• Phase 1 trial
• Phase 2 trial
• Phase 3 trial
• Primary endpoint
• Surrogate endpoint
• CDx