A Study to Evaluate the Safety and Efficacy of ION373 in Patients With Alexander Disease (AxD)

  • End date
    Nov 12, 2025
  • participants needed
  • sponsor
    Ionis Pharmaceuticals, Inc.
Updated on 12 July 2022


The purpose of this study is to evaluate the safety and efficacy of ION373 in improving or stabilizing gross motor function across the full range of affected domains in patients with AxD.


This is a Phase 1-3, multi-center, double-blind, placebo-controlled, multiple-ascending dose (MAD) study in up to 58 patients with AxD. Participants will be randomized in a 2:1 ratio to receive ION373 or matching placebo for a 60-week double-blind treatment period; then all participants will receive ION373 for a 60-week open-label treatment period. Multiple dose cohorts will be evaluated in the study. Cohorts will be enrolled sequentially. The initial participants in each dose cohort must be at least 8 years of age at the time of Screening.

Condition Alexander Disease
Treatment Placebo, ION373
Clinical Study IdentifierNCT04849741
SponsorIonis Pharmaceuticals, Inc.
Last Modified on12 July 2022


Yes No Not Sure

Inclusion Criteria

Clinical phenotype and brain imaging consistent with a diagnosis of Alexander disease
Documented genetic mutation in the GFAP gene
Aged ≥ 2 to 65 years old at the time of informed consent
Able and willing to meet all study requirements, including travel to Study Center, procedures, measurements and visits
Patients < 18 years old at Screening must have a trial partner (parent, caregiver or other)

Exclusion Criteria

Clinically significant abnormalities in medical history or physical examination
Any clinically significant laboratory abnormalities that would render a patient unsuitable for inclusion
Any contraindication or unwillingness to undergo MRI
Treatment with another investigational drug, biological agent, or device within 1 month of Screening, or 5 half-lives of investigational agent, whichever is longer; concurrent participation in any other clinical study (including observational and non-interventional studies)
Previous treatment with an oligonucleotide (including small interfering ribonucleic acid [siRNA]) within 4 months of Screening if single dose received, or within 12 months of Screening if multiple doses received
History of gene therapy or cell transplantation or any other experimental brain surgery
Obstructive hydrocephalus
Presence of a functional ventriculoperitoneal shunt for the drainage of CSF or an implanted CNS catheter
Known brain or spinal disease that would interfere with the LP process, CSF circulation or safety assessment
Hospitalization for any major medical or surgical procedure involving general anesthesia within 12 weeks prior to Screening or planned during the study
Have any other conditions, which, in the opinion of the Investigator would make the patient unsuitable for inclusion, or could interfere with the patient participating in or completing the study
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Additional screening procedures may be conducted by the study team before you can be confirmed eligible to participate.

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If you are confirmed eligible after full screening, you will be required to understand and sign the informed consent if you decide to enroll in the study. Once enrolled you may be asked to make scheduled visits over a period of time.

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Complete your scheduled study participation activities and then you are done. You may receive summary of study results if provided by the sponsor.

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