Cassava Sciences has long claimed its experimental drug, called simufilam, slows the cognitive decline of people with Alzheimer’s. On Friday, we learned how: The company recruited a large number of people into its clinical trial who don’t have Alzheimer’s.

People who almost certainly had Alzheimer’s were also included in the study, but in this group, a placebo outperformed Cassava’s drug.

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The conclusion, of course, is obvious: Simufilam is inactive. It’s an inert compound no more effective than a placebo. Cassava’s assertion that simufilam is showing “disease-modifying activity” falls apart given its study was opened to people who should have been ineligible because they were misdiagnosed with Alzheimer’s. Whether that was done intentionally or unwittingly isn’t known, but it’s certainly troubling and makes the case for immediate, regulatory intervention even stronger.

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