A Study of ALN-HSD in Healthy Adult Subjects and Adult Patients With Nonalcoholic Steatohepatitis (NASH)

Inclusion Criteria:

Part A Only

1. Has body mass index (BMI) ≥18 kg/m^2 and ≤28 kg/m^2
2. Has normal 12-lead electrocardiogram (ECG)

Parts B and C Only:

1. Has BMI ≥18 kg/m^2 and ≤40 kg/m^2
2. Has a diagnosis of NASH documented in the patient's medical history or a clinical suspicion of NASH based on defined study criteria
3. Has screening liver biopsy with NASH activity score (NAS) score of ≥3 per NASH Clinical Research Network (CRN) criteria

Exclusion Criteria:

Parts A, B and C:

1. Has any clinical safety laboratory result considered clinically significant and unacceptable by the Investigator
2. Has known active human immunodeficiency virus (HIV), hepatitis B virus (HBV), or hepatitis C virus (HCV) infection
3. Has known history or evidence of drug abuse, within 12 months prior to screening
4. Has evidence of other forms of known chronic liver disease
5. Has recently received an investigational agent
6. Has any uncontrolled or serious disease, medical or surgical condition that my interfere with participation or data interpretation
7. Has excessive alcohol intake for ≥ 3 months during past year
8. Has history of intolerance to SC injection(s)
9. Has international normalized ratio (INR) >1.2
10. Has platelet count <140x10^9/L

Part A Only

1. Has systolic blood pressure (BP) >140 mmHg and diastolic >90 mmHg;
2. Has used certain prescription drugs within last 14 days prior to screening
3. Has used certain over the counter (OTC) medication within 7 days prior to screening
4. Has estimated glomerular filtration rate (GFR) ≤60 mL/min/1.73m^2 at screening

Parts B and C Only

1. Has abnormal ECG
2. Has changes in certain prescription medications defined in the protocol within the specified timeframe prior to screening
3. Has GFR<45ml/min/1.73m^2