Shionogi Shares Update on Zatolmilast Fragile X Clinical Trials

October 27, 2025

Shionogi Inc., the company developing the investigational Fragile X treatment zatolmilast, has shared an update with the community. Their letter outlines the current status of two clinical trials in the U.S. and explains the next steps in the evaluation process.

You can read the full letter from Shionogi’s Chief Medical Officer below.

We know many families are eagerly awaiting news of these trials, and as Fragile X parents ourselves, we feel the same!  

Shionogi’s October 2025 letter to the Fragile X community with an update on zatolmilast clinical trials in the U.S.