C-KIT-positive tumor-specific antibody fragment

The purpose of the present invention is to provide a detection drug (diagnostic drug) and a therapeutic drug which are ingested in a tumor at an early stage in vivo, and which have c-KIT as a target molecule. As a result, the inventors have studied a molecular species to which c-KIT specifically binds, and a labeling agent and a therapeutic agent that bind to the molecular species, and found that, by combining a fragment of an anti-c-KIT antibody with IR700, it is possible to detect and treat tumors by aggregating the same within a short period of several hours after administration. Therefore, the present invention relates to a complex of IR700 and an antigen-binding fragment of an anti-c-KIT antibody, and to a detection agent and a therapeutic agent containing the complex as an active ingredient. Specifically, the present invention relates to a complex comprising IR700 and an antigen-binding fragment of an antibody having a complementarity determining region (CDR) in an antibody heavy chain comprising the am