RE:RE:RE:How does Accelerated Approval work
FDA's Expedited Approval Mechanisms for New Drug Products
"In December 1992, FDA also created the Accelerated Approval mechanism for full NDA approval through regulations. This mechanism applied to the approval of new drug products for serious or life-threatening conditions that provide meaningful therapeutic benefit to patients over existing treatments.It permitted the sponsor to show efficacy through clinical trials demonstrating an effect on an unvalidated surrogate endpoint that, nonetheless, was “reasonably likely to predict clinical benefit,” rather than a validated surrogate endpoint or clinical efficacy endpoint. For example, a study might evaluate the effect of a treatment on progression-free survival (PFS) rather than mortality. The use of a surrogate marker may substantially shorten the duration of a trial where the disease would take a long time to progress to the ultimate clinical efficiency endpoint, such as mortality."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4326266/