RESEARCH ARTICLE Prodrug AST-003 Improves the Therapeutic Index of the Multi-Targeted Tyrosine Kinase Inhibitor Sunitinib

Patients have responded well to the multi-targeted tyrosine kinase inhibitor (TKI) Sunitinib in the clinic. But the severe toxic side effects associated with Sunitinib limit its therapeutic index. To improve the therapeutic index of Sunitinib, a prodrug strategy was employed to modify Sunitinib. The inactive prodrug AST-003 can be converted to Sunitinib in vitro and in vivo. Compared with Sunitinib, AST-003 has unique biochemical, cellular and pharmacoki-netic properties with improved tolerability in mice and yield higher efficacy in tumor xeno-graft models. This prodrug strategy may constitute a novel paradigm to improve the therapeutic index of Sunitinib and other TKI or anti-angiogenesis drugs in general