A Study to Assess the Safety, Pharmacokinetics, and Activity of RO7790121 in Participants With Advanced MASH Liver Fibrosis

Inclusion Criteria: * Body mass index within the range of \>= 25 and \<=45 kilograms per square meter (kg/m\^2) * MASH with fibrosis score of F3 or F4 confirmed by transient elastography measurement \>=12.0 kPa and \<=25.0 kPa * Agreement to adhere to the contraception requirements Exclusion Criteria: * Weight gain or loss \>5% in the 3 months prior to baseline or \>10% in the 6 months prior to baseline * Bariatric surgery within 1 year prior to baseline * Current signs or prior history of decompensated liver disease * Complications or clinical evidence of portal hypertension * Lack of peripheral venous access * Other causes of liver disease based on medical history and/or centralized review of liver histology * History of liver transplantation * Current or prior history of hepatocellular carcinoma (HCC) * Uncontrolled hypertension * Concomitant Type 1 diabetes, or Type 2 diabetes with HbA1c \>10% * History of malignancy within 5 years prior to screening, with the exception of malignancies with a negligible risk of metastasis or death * Current, significant alcohol consumption or a history of significant alcohol consumption for a period of more than 3 consecutive months any time within 1 year prior to screening * Initiation of a medication of an antidiabetic, weight loss, lipid-modifying or anti-depressant drug class * Active tuberculosis requiring treatment within the 12 months prior to baseline * History of organ transplant