A pre-clinical safety study of PEGylated recombinant human endostatin (M2ES) in Sprague Dawley rats

PEGylated recombinant human endostatin (M2ES) exhibited prolonged serum half-life and enhanced antitumor activity when compared with endostatin. A pre-clinical study was performed to evaluate the safety of M2ES in rats. After intravenous (IV) infusions of M2ES at a dose level of 3, 15 and 75 mg/kg in Sprague Dawley (SD) rats, M2ES was well tolerated in animals, with no observable changes in clinical observation, body weight, food consumption, urine analysis, hematology and serum biochemical analysis. The increase of kidney weights, and slight to severe vacuolation and necrosis of proximal tubule epithelial cells in kidney were observed in 15 and 75 mg/kg M2ES groups, but this adverse-effect was reversible. In summary, the major toxicity target organ of M2ES might be kidney, and the no observed adverse effect level (NOAEL) of M2ES in rats was 3 mg/kg in this study. These pre-clinical safety data contribute to the initiation of the ongoing clinical study.