During my years as a Food and Drug Administration official, I learned that the available data on a new drug are seldom as complete and unequivocal as you might like. But getting drugs to patients can be a matter of life or death, so you need to make hard decisions. Fortunately, the regulations offer some flexibility so that the criteria for demonstrating efficacy are more lenient in certain critical situations. One of those pathways is called “accelerated approval.”

In 1992, the FDA instituted accelerated approval regulations, which allow drugs for serious conditions that fill an unmet medical need to be approved based on “surrogate endpoints.” A surrogate endpoint is an indirect indicator of improvement in the illness or disease, such as a laboratory measurement, radiographic image, physical sign, or other measure that is thought to predict clinical benefit but is not itself definitive. Using such an endpoint can considerably shorten the time to FDA approval.