Trofinetide is a synthetic analogue of a naturally occurring neurotrophic peptide sourced from a growth factor produced by brain cells known as IGF-1.
The results from the double-blind, randomised, placebo controlled trial showed that the highest dose of trofinetide had statistically significant clinical benefit until the treatment was stopped.
The trial was conducted in 82 patients aged 5-15 at 12 sites in the US.
Neuren executive chairman Dr Richard Treagus said: “These are deeply encouraging results that build on the clinical data generated from our first rett syndrome study.
“Taken together, this data provides a strong basis to move forward with the remaining steps in trofinetide’s development.
“We will discuss the results of this trial and our future plans with the US Food and Drug Administration (FDA) Division of Neurology as soon as possible and also provide the safety data to the Division of Psychiatry for consideration in our Fragile X syndrome development programme.”
The drug was also found to be well tolerated, with a good safety profile and no dose-limiting effects.
The firm plans to further investigate trofinetide in a trial that is due to start next year, with the Rett syndrome behaviour questionnaire as a primary efficacy measure and the clinical global impression of improvement as a secondary efficacy measure.
The FDA has granted both fast-track and orphan drug designation to the Rett syndrome and Fragile X syndrome programmes while they received orphan drug designation in the EU.