Research Study for Single-Patient Treatment of Cree Leukoencephalopathy/Vanishing White Matter Disease

Cree Leukoencephalopathy (CLE) is a rare and fatal neurodegenerative disorder predominantly affecting the Cree population in Northern Quebec. Characterized by progressive white matter degeneration, this condition leads to severe neurological impairment and decline, leading to premature death. Despite its significant impact on the affected population, there are currently no effective treatments for CLE. CLE is caused by a single founder pathogenic variant in the EIF2B5 gene and is therefore allelic to VWM.

Fosigotifator (FGT, ABBV-CLS-7262) has been developed and its safety and efficacy are currently being studied in a multi-center Phase 1b/2 clinical trial for Vanishing White Matter (VWM) by Calico in collaboration with AbbVie.

This study aims to provide under compassionate use program access to an investigational drug (FGT) for a patient diagnosed with CLE/VWM disease which has no treatment options currently available. The study will also evaluate the risk/benefit of FGT in slowing or halting the progression of white matter degeneration in a patient with CLE. By targeting the underlying pathophysiological mechanisms of white matter damage, FGT is expected to alleviate neurological symptoms and improve the quality of life for the patient. The outcomes of this study could provide critical insights into the disease's management and pave the way for the development of targeted therapies, ultimately offering hope to a population with limited treatment options.

Study Overview

• Status: Active, not recruiting
• Conditions: Vanishing White Matter; Cree Leukoencephalopathy
• Intervention / Treatment: Drug: Fosigotifator (FGT/ABBV-CLS-7262)

• Study Type: Interventional
• Enrollment (Estimated): 1
• Phase: Early Phase 1

Contacts and Locations

Study Locations

• Canada
  • Quebec
    • Montreal, Quebec, Canada, H4A3J1
      • McGill University Health Centre

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

The patient meets the following criteria:

• Molecularly confirmed diagnosis of CLE
• Pre-symptomatic or early symptomatic patient
• Signed informed consent from the Legal Guardians/caregivers (parents)

Exclusion Criteria:

N/A

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: N=1 trial

Drug: Fosigotifator (FGT/ABBV-CLS-7262); This study aims to provide under compassionate use program access to an investigational drug (FGT) for a patient diagnosed with Cree Leukoencephalopathy (CLE)/Vanishing White Matter (VWM) which has no treatment options currently available. The study will also evaluate the risk/benefit of FGT in slowing or halting the progression of white matter degeneration in a patient with CLE. By targeting the underlying pathophysiological mechanisms of white matter damage, FGT is expected to alleviate neurological symptoms and improve the quality of life for the patient. The outcomes of this study could provide critical insights into the disease's management and pave the way for the development of targeted therapies, ultimately offering hope to a population with limited treatment options.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Patient survival or need for continuous ventilatory support at 2 years	Patient survival (yes/no) or need for continuous ventilatory support (yes/no) at 2 years	3 years

Collaborators and Investigators

• Sponsor: McGill University Health Centre/Research Institute of the McGill University Health Centre

Study record dates

Study Major Dates

• Study Start (Actual): November 14, 2024
• Primary Completion (Estimated): November 30, 2027
• Study Completion (Estimated): December 31, 2027

Study Registration Dates

• First Submitted: October 11, 2024
• First Submitted That Met QC Criteria: November 26, 2025
• First Posted (Estimated): December 9, 2025

Study Record Updates

• Last Update Posted (Actual): December 30, 2025
• Last Update Submitted That Met QC Criteria: December 22, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Leukoencephalopathies
• Other Study ID Numbers: 2025-10780 (CLE-ABBV-CLS-7262)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: Yes