RE:RE:How does Accelerated Approval work According to FDA guidance entitled Clinical Trial Endpoints for the Approval of Cancer Drugs and Biologics" ....
. .. "While durable ORR has been used as a traditional approval endpoint n some circumstances, ORR has also been the most commonly used surrogate endpoint in support of accelerated approval. Tumor response is widely accepted by oncologists in guiding cancer treatments. Because ORR is directly attributable to drug effect, single-arm trials conducted in patients with refractory tumors where no available therapy exists provide an accurate assessment of ORR. Whether tumor measures such as ORR or PFS are used as an accelerated approval or traditional approval endpoint will depend on the disease context and the magnitude of the effect .."
.. "Treatment effect measured by PFS can be a surrogate endpoint to support accelerated approval, a surrogate endpoint to support traditional approval, or it can represent direct clinical benefit based on the specific disease, context of use, magnitude of the effect, the disease setting, location of metastatic sites, available therapy, the risk-benefit relationship, and the clinical consequences of delaying or preventing progression in key disease sites (e.g., delay of new lesions in the brain or spine) or delaying administration of more toxic therapies."
https://www.fda.gov/media/71195/download