In a recent statement, CONNECTA Therapeutics, a biotechnology company focused on disorders of the central nervous system, has announced the start of its Phase IIa clinical trial for CTH120, a novel drug aimed at treating adult males with Fragile X syndrome (FXS). This inherited condition currently has no approved therapies that directly target its underlying cause.

The new study builds on a successful Phase I trial that confirmed the drug’s safety in humans. This achievement marks an important step forward for the company and raises optimism about the possibility of a “disease-modifying” treatment—one that addresses the root biology of FXS rather than only easing its symptoms.

Understanding Fragile X Syndrome and CTH120’s Approach

Fragile X syndrome is the leading inherited cause of intellectual disability, affecting approximately 3 in 10,000 individuals. Because it is linked to the X chromosome, males are typically more severely impacted.

A key feature of FXS is disrupted neuroplasticity, which is the brain’s ability to adapt, reorganize, and form new neural connections. CTH120 is a first-in-class compound designed to act as a neuroplasticity modulator. It works by targeting the TrkB receptor in the brain, a critical regulator of how neurons communicate and adapt. By correcting dysfunction in this pathway, the drug aims to restore more typical brain activity.

“This study is intended to further assess the safety and tolerability of CTH120, while also providing important insights into its potential therapeutic effects by addressing pathways involved in impaired neuronal function in FXS,” said Jordi Fàbrega, Co-Founder and CEO of CONNECTA Therapeutics.

Details of the Clinical Study

The trial follows a randomized, double-blind, placebo-controlled design, widely considered the gold standard in clinical research. Its structure includes:

• Participants: 30 adult males aged 18 to 45 with severe Fragile X syndrome.
• Study Design: Participants will be evenly divided into two groups. One group will receive CTH120 twice daily, while the other will be given a placebo. Neither the participants nor the researchers will know who is receiving the active treatment.
• Objectives: The primary goal is to evaluate the drug’s safety and tolerability over time. Secondary objectives include studying how the drug is processed in the body (pharmacokinetics) and assessing any improvements in cognitive and behavioral symptoms.

Significance of the Research

For individuals and families affected by Fragile X syndrome, treatment options remain extremely limited. Dr. Rafael de la Torre Fornell, principal investigator at the Hospital del Mar Research Institute, highlighted the importance of advancing new therapies:

“FXS significantly impacts cognitive and behavioral functioning, greatly reducing quality of life for both patients and their families. There remains a substantial unmet medical need, as no disease-modifying treatments have been approved to date.”

The trial is being conducted at two prominent research centers in Spain and has received authorization from the Spanish Agency of Medicines and Medical Devices. Financial support comes from the Spanish government as well as the European Union’s NextGeneration EU initiative.

If the results are positive, this Phase IIa study could serve as a critical step toward larger, late-stage international trials, bringing the field closer to a potential breakthrough treatment for Fragile X syndrome.