Detailed Explanation
Accelerated Approval addresses a fundamental tension in drug development: the imperative to thoroughly demonstrate clinical benefit through adequate and well-controlled trials versus the urgency of making promising treatments available to patients with serious conditions. Established in 1992 initially for HIV/AIDS therapies, this pathway permits approval based on evidence that falls short of demonstrating the ultimate clinical outcome but provides reasonable likelihood that the drug will provide meaningful benefit to patients.
The scientific foundation of Accelerated Approval rests on surrogate endpoints or intermediate clinical endpoints that are reasonably likely to predict clinical benefit. Surrogate endpoints are laboratory measurements or physical signs that substitute for clinically meaningful outcomes. Intermediate clinical endpoints are clinical outcomes that occur earlier than ultimate outcomes but are still clinically meaningful themselves. For example, tumor response rates may serve as a surrogate for survival, or HIV viral load reduction may predict prevention of AIDS progression. The relationship between the surrogate and clinical benefit must be supported by scientific evidence, though definitive validation is not required.