Both ADCs showed strong in vitro antiproliferative activity on several c-KIT-positive human tumor cell lines representing GIST, AML, SCLC, and systemic mastocytosis regardless of their c-kit mutational status, and in vivo antitumor responses in imatinib-sensitive and -refractory GIST and systemic mastocytosis xenograft models, as well as in SCLC and AML models [178,179]. This evidence concerns the gene KIT and systemic mastocytosis.