Up to 80 healthy adult males, ≥ 18 and ≤ 55 years of age, are planned to be enrolled in the study.

The study will consist of 8 cohorts (Cohorts 1 to 8, 1 cohort per dose level). Each cohort will include 8 subjects (6 subjects receiving a single dose of the study drug NS101 and 2 subjects receiving a single dose of a matching placebo), for a total of 64 subjects planned for evaluation. A total of 21 blood samples will be collected in each cohort for PK analysis and a total of 14 blood samples will be collected in each cohort for PD analysis.

The study will consist of 8 cohorts (Cohorts 1 to 8, 1 cohort per dose level). Each cohort will include 8 subjects (6 subjects receiving a single dose of the study drug NS101 and 2 subjects receiving a single dose of a matching placebo), for a total of 64 subjects planned for evaluation.

For each dose level, the dose to be administered to each subject for a single infusion will be calculated based on subject's body weight, measured on Day 1.

In each cohort, subjects will receive a single infusion of NS101 or matching placebo under fasting conditions over a period of approximately 60 minutes at the target dose level. A total of 21 blood samples will be collected in each cohort for PK analysis and a total of 14 blood samples will be collected in each cohort for PD analysis. A total of 6 immunogenicity blood samples will be collected for ADA and NAbs. For each subject in cohort 5 to 8 only, one single CSF sample will be collected via lumbar puncture over the study, for PK and PD analysis.

Inclusion Criteria:

1. Male, non-smokers (no use of tobacco or nicotine products within 6 months prior to screening), ≥18 and ≤55 years of age, with BMI >18.5 and <30.0 kg/m2 and body weight ≥50.0 kg for males.

2. Healthy as defined by:

   1. the absence of clinically significant illness and surgery within 4 weeks prior to dosing.
   2. the absence of clinically significant history of neurological, endocrine, cardiovascular, respiratory, hematological, immunological, psychiatric, gastrointestinal, renal, hepatic, and metabolic disease.

3. Subject's score on the Sheehan Suicidality Tracking Scale (S-STS) at screening must be 0.

Exclusion Criteria:

1. Any clinically significant abnormality at physical examination, clinically significant abnormal laboratory test results or positive test for human immunodeficiency virus (HIV), hepatitis B, or hepatitis C found during medical screening.
2. Positive urine drug screen or alcohol breath test at screening or admission.
3. History of asthma, allergic rhinitis or urticaria, anaphylactic reactions, or any other clinically significant allergic reactions to any medication, including biologics, or food, or allergy to any excipient in the formulation.

Will decide once CSR is released

Subjects will be administered each treatment (NS101 or placebo), according to the block randomization scheme. The subjects and the clinical personnel involved in the collection, monitoring, revision, or evaluation of AEs, or personnel who could have an impact on the outcome of the study will be blinded with respect to the subject's treatment assignment (NS101 or placebo).