Efficacy of synthetic ACTH in confirmed and presumed monogenic developmental and epileptic encephalopathies.
OBJECTIVE Adrenocorticotropic hormone (ACTH) is an effective treatment for infantile epileptic spasms syndrome (IESS); however, its mechanism of action remains incompletely understood. This study aimed to evaluate ACTH treatment response at the level of protein-protein interactions (PPIs) in patients with confirmed and presumed monogenic developmental and epileptic encephalopathies (DEEs). METHODS Medical records of patients with DEEs followed at our center between 2017 and 2025 were retrospectively reviewed. Patients receiving ACTH therapy who harbored pathogenic, likely pathogenic, or variants of uncertain significance (VUS) were included in the study, whereas those with chromosomal abnormalities and insufficient clinical or follow-up data were excluded. Clinical and electroencephalographic (EEG) responses to ACTH therapy were evaluated at the 2-week (day 14) and 3-month follow-up visits. Maintenance of a ≥50% reduction in seizure frequency at 3-month follow-up defined responders. Gene Ontology and PPI network analyses were performed to investigate relationships between genotype and treatment response. RESULTS Among the 245 patients with DEEs, 69 had a confirmed genetic etiology, of whom 10 met the inclusion criteria. At 2-week follow-up, 5 of 10 patients (SCN2A, ELOVL4, CACNA1E, TRRAP) achieved seizure freedom, while 3 (PIGT, SCN1A, ZNF526) showed ≥50% reduction. At month 3, 66.6% (6/9) of patients were classified as responders. At 1 year, patients with SCN2A and PIGT variants showed sustained ≥50% seizure reduction, normalization of background EEG activity, and resolution of epileptiform discharges. PPI analysis revealed network interactions between CALM-SCN2A/CACNA1E and PRKAC-SCN1A, whereas the TRRAP-ATF2 interaction showed low confidence, and no reliable interaction was identified for PIGT. SIGNIFICANCE These findings suggest that ACTH may be associated with sustained electroclinical improvement in selected genetically defined DEEs. The identified network-level interactions between ion channel-related genes and intracellular signaling pathways provide a potential molecular framework for understanding variability in treatment response.