Antibody specifically binding to extracellular second loop of claudin 3, its fragment, and uses thereof

The present invention is intended for application to cancer cell detection, diagnosis, imaging, cancer treatment of antibodies and functional fragments thereof that specifically bind to ECL-2 of Cladin 3 (anticancer use of the antibody itself, ADC and CAR-expressing cells (especially, Immune cells) and antibodies and functional fragments thereof comprising the unique CDR sequences which have a pronounced effect on these uses. Antibodies that specifically bind to ECL-2 of Claudine 3 and functional fragments thereof have applications in cancer cell detection, diagnosis, imaging, and cancer treatment over other cancer antigens or existing antibodies that target ECL-1 of Claudine 3 (ADC). And application to CAR-T). In particular, the antibody comprising a specific CDR sequence provided by the present invention as a specific example of the present invention not only possesses anti-cancer ability on its own but also shows excellent cancer cell targeting ability without cross-reactivity with other cladin families, and binds to mouse cladin 3 so that toxicity and It is also advantageous for the verification of activity through non-clinical experiments of efficacy evaluation, and possesses the characteristics such as cell internalization and shows a remarkable effect in the application to the above uses.