Rare Diseases Clinical Trials Update: Week 23, 2026

Published June 5, 2026 — 5 trials covered

By Victor Lafforgue, Founder of TrialsAlert. Blog posts are AI-drafted from ClinicalTrials.gov source data and reviewed by the editorial team. See our editorial policy for details.

CSL312_3003 Safety and Pharmacokinetic Study in Subjects 2 to 11 Years of Age With Hereditary Angioedema

This completed Phase 3 study tested CSL312, also known as Garadacimab, in children aged 2 to 11 with hereditary angioedema (HAE). The treatment is a monoclonal antibody designed to prevent painful swelling attacks common in HAE. Results from multiple countries are now available, and if positive, this could provide a safer and more effective preventive option for young patients living with this rare condition.

RGX-121-3102 Gene Therapy in Participants With MPS II (Hunter Syndrome)

This Phase 3 trial is exploring RGX-121 gene therapy for children with neuronopathic MPS II, also called Hunter Syndrome. This gene therapy aims to address the genetic cause of the disease and may improve brain development and function. Although the study is active but not recruiting, results are pending from a small group of participants in the United States, offering hope for a new treatment that targets the root of this rare disorder.

Clinical Study of DTX301 AAV-Mediated Gene Transfer for Ornithine Transcarbamylase (OTC) Deficiency

In this Phase 3 study, DTX301 gene therapy is being tested for patients with late-onset OTC deficiency, a rare metabolic disorder affecting ammonia processing. If successful, this treatment could help keep ammonia levels safe and reduce related health complications. The study is ongoing but not currently enrolling new participants, with sites located in the United States and Europe, reflecting international efforts to find better treatments for this condition.

Ensuring Access to Optimal Therapy in CF: The ENACT Study

This Phase 4 trial is investigating new drug combinations and the role of genetics in children with cystic fibrosis (CF) to help tailor treatments better. The goal is to identify which patients will benefit most from existing therapies, potentially lowering side effects and healthcare costs. The study is recruiting in the United States and plans to enroll about 100 children, aiming to improve how CF treatments are personalized.

Double-Blind Trial of Everolimus for Improving Social Abilities in PTEN Germline Mutations

This Phase 2 trial is testing everolimus, an oral medication, for people with PTEN Hamartoma Tumor Syndrome, a rare genetic disorder that can affect social abilities. The study includes both children and adults and aims to see if this treatment can improve social skills over one year. Recruiting is underway in the United States, offering a potential new option for managing social difficulties linked to this syndrome.

TrialsAlert subscribers received the full impact-classified briefing and doctor-ready report this week. Get weekly briefings at trialsalert.com.