Molecular signatures predictive of response to mecasermin in children with Rett syndrome

Purpose: Rett syndrome (RTT) is a devastating neurodevelopmental disorder without effective treatments. Attempts at developing targeted therapies have been relatively unsuccessful, at least in part, because the genotypical and phenotypical variability of the disorder. Therefore, identification of biomarkers of response and surrogate endpoints is a high priority. Methods: We used RNA sequencing to measure differential gene expression in whole blood samples of participants patients (n=9) were analysed from phase I mecasermin trial Results: When all patients (n=9) were analysed, gene expression was unchanged during the study (baseline vs. end of treatment). Conclusions: Our preliminary analyses revealed gene expression profiles associated with differential breathing phenotype response to mecasermin in RTT. Whole blood mRNA profiles of patients with RTT and MRD Timepoint 0 = baseline Timepoint 1 = after multiple ascending dose phase Timepoint 2 = washout period Timepoint 3 = after open label extension phase