Evaluation of the Relative Performance of Drug-Induced Skeletal Muscle Injury Biomarkers in Rats

Novel skeletal muscle (SKM) injury biomarkers that have recently been identified may outperform or add value to the conventional SKM injury biomarkers aspartate transaminase (AST) and creatine kinase (CK). The relative performance of these novel biomarkers of SKM injury including skeletal troponin I (sTnI), myosin light chain 3 (Myl3), CK M Isoform (Ckm), and fatty acid binding protein 3 (Fabp3) was assessed in 34 rat studies including both SKM toxicants and compounds with toxicities in tissues other than SKM. sTnI, Myl3, Ckm, and Fabp3 all outperformed CK or AST and/or added value for the diagnosis of drug-induced SKM injury (ie, myocyte degeneration/necrosis). In addition, when used in conjunction with CK and AST, sTnI, Myl3, CKm, and Fabp3 individually and collectively improved diagnostic sensitivity and specificity, as well as diagnostic certainty, for SKM injury and responded in a sensitive manner to low levels of SKM degeneration/necrosis in rats. These findings support the proposal that sTnI, Myl3, Ckm, and Fabp3 are suitable for voluntary use, in conjunction with CK and AST, in regulatory safety studies in rats to monitor drug-induced SKM injury and the potential translational use of these exploratory biomarkers in early clinical trials to ensure patient safety.