In a 1993 clinical trial of fialuridine--a drug originally designed as a therapy for hepatitis B--5 out of 15 patients died from sudden liver failure. A new study in PLOS Medicine found that mice with humanized livers demonstrate the drug's toxicity. The research suggests that the mouse model could have predicted the toxicity of the drug, and the study authors believe the model should be used in preclinical screening of drugs for liver toxicity before they are given to human participants in clinical trials. Study