The present invention derives from the unexpected finding that necroptosis is a novel biomarker and target for therapy in patients with liver failure such as acute liver failure (ALF) and acute-on-chronic liver failure (ACLF). RIPK1, MLKL or RIPK3 can be detected and quantified in serum or plasma, and used as a biomarker for outcome in ACLF and other diseases involving aberrant necroptosis. By antagonising RIPK1, MLKL or RIPK3 many of the unwanted consequences or symptoms of acute-on-chronic liver failure (ACLF) may be reduced. The present invention utilises these findings to identify and provide antagonists of RIPK1, MLKL and RIPK3 that may be used in the treatment or prevention of ACLF. The present invention utilises these findings to identify and provide antagonists of RIPK1, MLKL or RIPK3 that may be used in the treatment or prevention of aberrant necroptosis in the kidney, brain, liver or other organ of the body.