Purpose: KIT is the major oncogenic driver of gastrointestinal stromal tumors (GIST). Imatinib, sunitinib, and regorafenib are approved therapies; however, efficacy is often limited by the acquisition of polyclonal secondary resistancemutations inKIT,with those located in the activation (A) loop (exons 17/ 18) being particularly problematic. Here, we explore the KIT-inhibitory activity of ponat...