First in Human (FIH) Study of ALN-SOD in Adult Participants With Amyotrophic Lateral Sclerosis Associated With Mutation in the SOD1 Gene (SOD1-ALS)

Key Inclusion Criteria:

1. Weakness attributable to ALS and a SOD1 mutation that has been previously describedas associated with ALS or is considered likely to cause ALS, as defined in theprotocol

2. Slow vital capacity (SVC) ≥50% predicted value based on age, gender and height,measured in upright position

3. Body Mass Index (BMI) ≤35 kg/m2 at time of screening

4. If participants are taking riluzole or edaravone, they must be on a stable dose forat least 4 weeks prior to initial dosing visit and are expected to remain at thatdose until the end of the study

5. Platelet count >50,000/microliter

6. Has normal blood pressure readings, as defined in the protocol

Key Exclusion Criteria:

1. Concurrent participation in another interventional clinical trial

2. Has had a tracheostomy

3. Has dementia, as assessed by the investigator

4. Has uncontrolled psychiatric disease, including psychosis, active or recent suicidalideation, untreated major depression, in the past 30 days

5. Has a medical history of brain or spinal disease/injury that would interfere withthe lumbar puncture (LP) process, CSF circulation or safety assessment, as definedin the protocol

6. Presence of an implanted shunt for the drainage of CSF or an implanted centralnervous system (CNS) catheter

7. Presents any concern to the study investigator that might confound the results ofthe study or poses an additional risk to the participant by their participation inthe study

8. Was hospitalized (ie, >24 hours) for any reason other than ALS within 30 days ofscreening

9. Has received treatment with tofersen within 6 months prior to screening

NOTE: Other protocol defined inclusion / exclusion criteria apply