A Clinical Study to Investigate the Safety and Tolerability of Efimosfermin Alfa Injection in Participants With Known or Suspected F2- or F3-stage MASH

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 with evidence of fibrosis

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.
• Alpha-fetoprotein >=20 nanogram per milliliter (ng/mL)
• 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