By: Russell Katz, M.D.
If no treatments are developed to prevent, cure or slow the progression of Alzheimer’s disease (AD), the number of Americans suffering from this disease will grow from 5.4 million to as many as 16 million by 2050, according to estimates by the Alzheimer’s Association.
The aging of baby boomers is fueling what could turn a public health problem into a public health crisis.
So it is with a sense of urgency that FDA has issued a new draft guidance to assist, encourage, and facilitate those working to develop drugs to treat the early stages of AD. The ultimate goal: preventing or arresting AD before the brain suffers too much damage.
AD is a degenerative disease that kills brain cells over time, eventually impairing patients’ thinking and function. There is no simple laboratory test for AD, so diagnoses are generally based on patients’ symptoms. The lack of a laboratory test creates an obvious challenge: identifying people at risk of developing AD, as well as those who are in the earliest stages of the disease – when symptoms are difficult to perceive. Yet these are precisely the people one would want to enter into studies of treatments to prevent AD, or to delay progression of AD in its early stages.
FDA’s guidance addresses the challenge of choosing such patients for clinical trials to study drugs with the potential to help treat AD. The guidance also considers the evidence drug makers can use to show that a new medicine can effectively treat symptoms of AD or, better yet, slow progress of the disease.
The guidance recognizes, for example, that patients with very early AD may not yet show problems in performing daily life tasks—in other words, their symptoms may be difficult or impossible to detect. In studies of drugs to treat more advanced AD there is an effort to show effects on both thinking ability and function in daily activities. When there are not yet problems with daily function, the guidance says that showing evidence that a drug delays impairment of thinking may provide sufficient evidence to support “accelerated” approval, where there is a requirement to show, after the drug is approved, that the effect on thinking persists over time.
Another issue addressed in the guidance is how to demonstrate that a new medicine is actually modifying or slowing AD. In other words, the drugs now approved for AD may improve thinking and daily function, but despite these improvements, the disease continues to progress, worsening as it would without the drug.
FDA is seeking comments on the guidance, and these comments will be considered before FDA publishes a final guidance. The draft guidance is in the Federal Register.
FDA is devoted to changing the trajectory of this devastating, life-stealing disease, and looks forward to seeing new medicines that can help accomplish this.
Russell Katz, M.D., is director of FDA’s Division of Neurology Products, which regulates and reviews new drugs and marketing applications for treatment of neurological conditions, including Alzheimer’s disease.