Overview

This study will evaluate the safety and tolerability of Efimosfermin Alfa for participants with known or suspected MASH with fibrosis consistent with stage F2 or F3.

Eligibility

Inclusion Criteria:

• Able and willing to understand and sign a written informed consent form (ICF) that must be obtained prior to the initiation of study procedures
• Age \>=18 through \<=75 years at enrolment
• History or presence of 2 or more of the 5 components of metabolic syndrome per American Heart Association definition
• History or presence of known or suspected MASH

Exclusion Criteria:

• ALT or AST \>=5 × upper limit of normal (ULN)
• Total bilirubin (BILI) \>=1.3 milligram per deciliter (mg/dL). Individuals with documented Gilbert's syndrome may be enrolled if they experienced an isolated increase in total BILI of \>=1.3 mg/dL and direct BILI is \<=20% of total BILI; otherwise, the individual will be excluded.
• Serum albumin \<=3.5 grams per deciliter (g/dL)
• International normalized ratio (INR) \>=1.3 not due to therapeutic anticoagulation. Individuals receiving chronic anticoagulant treatment with higher INR values may be enrolled at the discretion of the Investigator and Study Medical Monitor.
• Alkaline phosphatase (ALP) \>=2 × ULN
• Platelet (PLT) count \<140 000 per (/) cubic millimeter (mm\^3); individuals with a PLT count between 110,000/mm\^3 and 140,000/mm\^3 may be enrolled after discussion with the Study Medical Monitor
• Serum creatinine \>=1.5 mg/dL or creatinine clearance \<=60 milliliter (mL)/minute (min)/1.73 square meter by Chronic Kidney Disease Epidemiology Collaboration equation.
• HbA1c \>=9.0%
• Model for End-Stage Liver Disease (MELD) 3.0 score \>=12 unless the score is elevated in the absence of liver dysfunction (eg, Gilbert's syndrome)
• Phosphatidylethanol (PEth) \>=80 nanogram per milliliter (ng/mL) at Screening
• Known co-infection with any of the following: a. Human immunodeficiency virus; b. Hepatitis B virus; c. Hepatitis C virus (HCV); d. Hepatitis D virus; or e. Hepatitis E virus.
• Chronic liver disease from any other cause including, but not limited to, alcoholic liver disease; evidence of portal hypertension; viral hepatitis, or any history or evidence of cirrhosis; or decompensated liver disease such as clinical ascites, bleeding gastroesophageal varices, hepatorenal syndrome, or hepatic encephalopathy prior to Screening or Day 1.
• Current or history of excessive alcohol intake for \>=3 months within the 12-month period prior to Screening