Servier has agreed to acquire Medicxi company Kaerus Bioscience's potential Fragile X syndrome (FXS) treatment, KER-0193.

Servier will pay Kaerus Bioscience upfront, with additional development and commercial earn-out payments that could bring the deal's total value to $450m.

The strategic move positions Servier to expand its pipeline with assets that target rare indications.

The safety and tolerability of KER-0193 were confirmed in a Phase I clinical trial conducted by Kaerus in March 2025.

This study, involving healthy volunteers, demonstrated the “excellent pharmacokinetics” of the treatment.

The orally bioavailable small molecule, KER-0193, modulates BK channels, which are linked to the genetic cause of FXS.

In preclinical trials, the therapy showed potential in improving behavioural, cognitive and sensory deficits associated with the syndrome.

The US Food and Drug Administration (FDA).has granted KER-0193 both rare paediatric drug and orphan drug designations for the treatment of FXS.

Servier is planning to initiate a Phase II trial in 2026 to further investigate KER-0193 in FXS patients across Europe and America.

FXS is recognised as the most prevalent genetic cause of autism spectrum disorder (ASD).

Servier research and development executive vice-president Claude Bertrand stated: “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.”

In March 2025, Servier made a licensing agreement with Black Diamond Therapeutics for BDTX-4933, a targeted therapy aimed at treating solid tumours.