The Food and Drug Administration on Monday approved Biogen’s Alzheimer’s drug albeit to mixed reviews. In announcing its decision, the agency noted that the drug was granted “Accelerated Approval,” which allows for drugs targeted at serious conditions that fill an unmet medical need to be approved “based on a surrogate endpoint.”
Part of the controversy in the medical community surrounding the drug’s approval stems from data collected during two Phase 3 clinical trials. One study met the primary endpoint and showed a reduction in clinical decline, while the other did not. In November 2020, the Peripheral and Central Nervous System Drugs Advisory Committee had said it was not reasonable to consider clinical benefit of the drug based on one successful study.
But, the FDA noted in a statement regarding its decision, the committee did not discuss Accelerated Approval, which considers surrogate endpoints. In 1992, the agency instituted Accelerated Pathway “mindful of the fact that it may take an extended period of time to measure a drug’s intended clinical benefit.”
“A surrogate endpoint used for accelerated approval is a marker – a laboratory measurement, radiographic image, physical sign or other measure that is thought to predict clinical benefit, but is not itself a measure of clinical benefit,” according to the FDA. “Likewise, an intermediate clinical endpoint is a measure of a therapeutic effect that is considered reasonably likely to predict the clinical benefit of a drug, such as an effect on irreversible morbidity and mortality (IMM).”
Using surrogate or intermediate clinical endpoints can save “valuable time” in the approval process, the agency noted. However, the company that receives Accelerated Approval will still need to conduct confirmatory trials and submit data for review. If the confirmatory trials fail to verify clinical benefit, the FDA may withdraw approval or change label indication of the drug.
Biogen’s Aduhelm is the first drug approved for Alzheimer’s in nearly 20 years. The FDA noted that although the “data are complicated with respect to its clinical benefits,” the agency determined that there is “substantial evidence” that the drug reduces amyloid beta plaques in the brain “and that the reduction in these plaques is reasonably likely to predict important benefits to patients.”
“The need for treatments is urgent: right now, more than 6 million Americans are living with Alzheimer’s disease and this number is expected to grow as the population ages,” the FDA said. “Alzheimer’s is the sixth-leading cause of death in the United States.”