Clinical Trial

Disease: Mucopolysaccharidosis II, MPS II, (NCT05238324)

Disease info:

Mucopolysaccharidosis type II (MPS II), also known as Hunter syndrome, is a condition that affects many different parts of the body and occurs almost exclusively in males. It is a progressively debilitating disorder; however, the rate of progression varies among affected individuals.

Individuals with this disorder often have a large head (macrocephaly), a buildup of fluid in the brain (hydrocephalus), an enlarged liver and spleen (hepatosplenomegaly), and a soft out-pouching around the belly-button (umbilical hernia) or lower abdomen (inguinal hernia).

There are two types of MPS II, called the severe and mild types. While both types affect many different organs and tissues as described above, people with severe MPS II also experience a decline in intellectual function and a more rapid disease progression.The life expectancy of these individuals is 10 to 20 years. Individuals with mild MPS II also have a shortened lifespan, but they typically live into adulthood and their intelligence is not affected. Heart disease and airway obstruction are major causes of death in people with both types of MPS II.

Frequency:
MPS II occurs in approximately 1 in 100,000 to 1 in 170,000 males.
Official title:
A Phase 1 Open-Label Dose Escalation Study to Evaluate the Safety and Efficacy of HMI-203 in ERT-Treated Adults With Mucopolysaccharidosis Type II (MPS II) (juMPStart Trial)
Who:
Sponsor:

Homology Medicines, Inc

Partners:
Locations:

United States, California Oakland, California, United States, 94609 Recruiting UCSF Benioff Children's Hospital Oakland

United States, Connecticut New Haven, Connecticut, United States, 06519 Recruiting Yale Center for Clinical Investigation

United States, New Jersey Hackensack, New Jersey, United States, 07601 Recruiting Hackensack University Medical Center

United States, Utah Salt Lake City, Utah, United States, 84113 Recruiting University of Utah Pediatric Genetic & Metabolism Clinic

United States, Virginia Fairfax, Virginia, United States, 22030 Recruiting Lysosomal and Rare Disorders Research and Treatment Center, Inc.

Canada, Alberta Calgary, Alberta, Canada, T2E 7Z4 Recruiting M.A.G.I.C. Clinic, Ltd.

Study start:
Sep. 8, 2022
Enrollment:
0
Gene editing method:
Nuclease-free gene-editing
Type of edit:
Gene replacement
Gene:
Phenylalanine hydroxylase (PAH)
Delivery method:
Adeno-associated virus (AAVHSC15) - In-vivo
Trial link:
https://clinicaltrials.gov/study/NCT05238324?term=nct05238324&rank=1
Safety updates:

(27-07-2023) Encouraging Initial Data from First Dose Level in the pheEDIT Trial Evaluating Gene Editing Candidate HMI-103 in Adults with Classical PKU

Note:
This trial was withdrawn. Homology Medicines has discontinued development of this program.
Indicator
IND Enabling Pre-clinical
Phase I Safety
Phase II Safety and Dosing
Phase III Safety and Efficacy

Status:

Description

This Phase 1 study will evaluate the safety and efficacy of HMI-203 gene therapy in adult male participants with MPS II currently being treated with standard-of-care idursulfase ERT or equivalent. Participants will receive a single dose of HMI-203 administered intravenously. There are 3 planned dose cohorts which will consist of 3 participants each.

Entry into the first dose cohort will be separated by a 60-day dosing interval between each participant to allow the Homology Medicines medical monitor to review safety and efficacy data prior to the second and third participants being enrolled. Enrollment of subsequent participants, in cohorts 2 and 3, will be separated by a 21-day dosing interval between each participant for review of safety and efficacy data.

Escalation to the next dose cohort will occur after 21 days of safety, efficacy, and biomarker data have been reviewed by the Homology Medicines independent DMC.

This entire study is comprised of 5 years, with the most frequent follow up visits occurring in the first year.

Last updated: Jun. 23, 2025
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