NNZ-2591 in Children and Adolescents With Phelan-McDermid Syndrome

Background and Objectives: Phelan-McDermid syndrome (PMS) is a rare genetic neurodevelopmental disorder with no currently approved treatments. NNZ-2591, a synthetic analog of the insulin-like growth factor 1 metabolite cyclic glycine-proline, was evaluated in children and adolescents with PMS in a phase 2, multisite, open-label clinical trial. Methods: < 0.05 indicating significance. Results: > 300 μg ⋅ h/mL experienced improvements in the PMS-specific CGI of Improvement scores. Discussion: For children and adolescents with PMS, NNZ-2591 appeared generally safe, with clinicians and caregivers reporting meaningful improvements in important symptoms of PMS. The benefit-risk and pharmacokinetic profiles support continued evaluation of NNZ-2591 for PMS. Trial Registration Information: ClinicalTrials.gov; NCT05025241. Submitted August 24, 2021. First participant enrolled on August 8, 2022.