The fosgonimeton translation

The prodrug that took dihexa into humans, and failed

The closest thing to a human test of dihexa is fosgonimeton (ATH-1017), dihexa's phosphate prodrug, developed by Athira Pharma. Injected under the skin, it is converted in the blood into dihexa, which the company calls ATH-1001 or fosgo-AM. It reached Phase 2 and Phase 2/3 Alzheimer's trials, and it did not work.

This unit clears up a common confusion in both directions. Fosgonimeton is not an unrelated molecule: the FDA's substance registry lists ATH-1001 as a name for dihexa and records fosgonimeton as its prodrug. But an injected prodrug at trial doses is not the same thing as dihexa powder swallowed at an unknown dose and purity, so the trials say a lot about the molecule and very little about what people buy online.