A Study of VGL101 in Patients with Adult-Onset Leukoencephalopathy with Axonal Spheroids and Pigmented Glia

Key Inclusion Criteria:

• Participants who have documentation of a gene mutation in the CSF1R gene

• Participants fulfill both (Parts A and B) of the following criteria:

1. The participant has more than 2 findings of clinical signs or symptoms in thefollowing categories:

2. Cognitive impairment or psychiatric problem

3. Pyramidal signs on neurological examination

4. Extrapyramidal signs, such as rigidity.

5. Epilepsy

6. MRI findings consistent with ALSP, specifically, bilateral cerebral whitematter lesions with or without thinning of the corpus callosum, on theScreening MRI.

• The participant must have a study partner (i.e., caregiver, family member, friend,etc.) who, in the investigator's judgment, has frequent and sufficient contact withthe subject so as to be able to provide accurate information about the participant'shealth and cognitive and functional abilities. The study partner must be willing tosign a study partner ICF.

Key Exclusion Criteria:

• The participant has any neurological disease that poses a risk to the participant orcan produce cognitive, motor, or behavioral impairment similar to ALSP, including,but not limited to, brain tumor, hydrocephalus, Alzheimer's disease, frontotemporaldementia (FTD), ALS, stroke, Huntington disease, multiple sclerosis, Parkinson'sdisease, and Down syndrome.

• Participant with any condition or situation that, in the opinion of the investigatoror sponsor medical personnel, may place the subject at significant risk, confoundthe study results, or interfere significantly with the participant's participationin the study.