Servier, an independent international pharmaceutical group governed by a foundation, announced that it has entered into a definitive agreement with Kaerus Bioscience for the acquisition of KER-0193, a potential treatment for Fragile X syndrome (FXS), the most common genetic cause of autism spectrum disorder (ASD). This acquisition demonstrates Servier's commitment to building a neurology franchise by expanding its pipeline with assets targeting rare indications for patients with high unmet need.

KER-0193 was discovered and developed by Kaerus Bioscience, a UK headquartered biotechnology company co-founded by Medicxi in 2016. Kaerus Bioscience successfully completed a Phase 1 clinical study of KER-0193 in healthy volunteers in March 2025, which confirmed the treatment to be safe and well tolerated with excellent pharmacokinetics. Additionally, KER-0193 has been granted both Orphan Drug Designation and Rare Pediatric Drug Designations for the treatment of FXS by the U.S. Food and Drugs Administration (FDA).

Under the terms of the agreement, Kaerus Bioscience will receive an upfront payment for the sale of KER-0193 and will also be eligible for development and commercial earn-out payments. The total value of the deal could reach up to $450M.

Claude Bertrand, Executive Vice-President of R&D at Servier, said: "KER-0193 is Servier's first asset acquisition in neurology and so marks a significant milestone in our 2030 strategy, reinforcing our long-term commitment to establishing a leading neurology franchise focused on rare diseases. It reflects our determination to build a differentiated pipeline of innovative therapies for patients with underserved needs. We are particularly excited to advance KER-0193 as we believe it holds meaningful promise for patients living with Fragile X syndrome, a condition for which no approved treatment options exist today." 

Dr. Robert Ring, Chief Executive Officer of Kaerus Bioscience, said: "We strongly believe in the therapeutic potential of KER-0193 in Fragile X syndrome. Servier's firm commitment to neurology and global capabilities make it the ideal partner to further develop KER-0193 for patients worldwide." 

Michèle Ollier, Venture Partner and co-founder of Medicxi, said: "Kaerus Bioscience was created by Medicxi to advance a clear product vision to develop a potential first-in-disease therapy for Fragile X syndrome. We are extremely proud of the cutting-edge scientific progress achieved by the Kaerus team under Dr Ring's leadership, and are excited that this deal with Servier will accelerate the development of KER-0193, bringing us closer to ensuring this innovative new therapeutic can reach those patients who are most in need."

KER-0193 is an orally bioavailable small molecule modulator of BK channels that specifically addresses abnormal function of BK channels linked to the genetic cause of FXS. In preclinical studies, KER-0193 has already demonstrated broad therapeutic-like effects on improving syndrome-relevant behavioral, sensory and cognitive deficits. As part of the development strategy, Servier will prepare the launch of a Phase 2 clinical trial in 2026 in FXS patients in America and Europe. 

FXS is a rare genetic syndrome of neurodevelopment characterized by a wide range of cognitive and behavioral challenges. It is the most common genetic cause of intellectual disability and the leading single-gene form of autism spectrum disorder (ASD), affecting approximately 1 in 7,000 males and 1 in 11,000 females globally. There are currently no approved treatments for FXS, which accounts for approximately 1% of ASD and intellectual disability cases globally.