MZ-1866 AAV9 gene therapy delivered into the brain ventricles for Pitt Hopkins syndrome

Phase 1/2 First-in-Human Study to Evaluate the Safety, Tolerability, and Efficacy of MZ-1866, an AAV-9 Gene Therapy Delivered by Intracerebroventricular Injection to Participants With Pitt Hopkins Syndrome

Phase1; Phase2 Interventional Mahzi Therapeutics · NCT07135050

This will test a single intracerebroventricular dose of MZ-1866 AAV9 gene therapy in children and adults with Pitt Hopkins syndrome to see if it is safe and tolerable.

Quick facts

PhasePhase1; Phase2
Study typeInterventional
Enrollment12 (estimated)
Ages2 Years to 25 Years
SexAll
SponsorMahzi Therapeutics Industry-sponsored
Locations4 sites (Oakland, California and 3 other locations)
Trial IDNCT07135050 on ClinicalTrials.gov

What this trial studies

This Phase 1/2 study gives a single intracerebroventricular (ICV) dose of MZ-1866, an AAV9-based gene therapy designed to address TCF4 dysfunction in Pitt Hopkins syndrome. Participants are followed with regular safety monitoring including physical exams, laboratory tests, ECGs, and adverse event reporting. Neurodevelopmental assessments and caregiver diaries/questionnaires are used periodically to track changes in behavior and development. Enrollment requires a pathogenic or likely pathogenic TCF4 mutation and excludes individuals with large deletions or CNS conditions that prevent safe ICV delivery.

Who should consider this trial

Good fit: Ideal candidates are children or adults with a confirmed pathogenic or likely pathogenic TCF4 mutation and clinical features of Pitt Hopkins who are medically able to undergo an intracerebroventricular procedure and attend follow-up visits.

Not a fit: Patients with very large deletions that include TCF4 (>12 Mbp), other unrelated genetic or medical conditions that would confound outcomes, or structural CNS abnormalities that make ICV injection unsafe are unlikely to benefit.

Why it matters

Potential benefit: If successful, this approach could reduce key neurological symptoms and improve development and daily functioning for people with Pitt Hopkins syndrome.

How similar studies have performed: AAV9 gene therapies have shown benefit in other genetic neurological disorders (for example spinal muscular atrophy) and preclinical work supports ICV delivery, but using MZ-1866 for Pitt Hopkins is a novel, early-stage approach.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* The participant has a TCF4 gene mutation confirmed as "pathogenic" or "likely pathogenic" by whole exome sequencing, whole genome sequencing, gene panel, single gene testing, or microarray, performed at an accredited laboratory
* Clinical phenotype consistent with Pitt Hopkins Syndrome, in the opinion of the investigator
* The participant, or the participant's parent or legal guardian, is willing to provide access to prior medical records for the collection of demographics and diagnostic and treatment history

Exclusion Criteria:

* A deletion that includes the TCF4 gene that is over 12 Mbp in size
* Another genetic mutation or clinical comorbidity not associated with Pitt Hopkins Syndrome that could potentially confound interpretation of the study data
* A central nervous system structural or vascular abnormality that is a contraindication to the ICV administration procedure, including but not limited to: signs or symptoms of increased intracranial pressure, history of a space-occupying lesion, or presence of a ventricular shunt that would preclude ICV procedures or safety assessments, or increase risk to the participant
* Not able to receive prophylactic corticosteroids due to a medical contraindication or participant has a history of a condition that could worsen with corticosteroid therapy as assessed and determined by the Investigator
* Not able to undergo MRI procedures
* Cannot be anesthetized for the ICV injection

Where this trial is running

Oakland, California and 3 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Pitt Hopkins SyndromeMZ-1866AAV9 Gene TherapyGene TherapyICVIntracerebroventricularTCF4PTHS
Last reviewed 2026-06-10 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.