The high affinity of aromatic/heterocyclic sulphonamides acting as CAIs for CA IX and XII, which are found in rather low concentration in most normal tissues but are overexpressed in many hypoxic tumours20–22 led Neri’s and other groups to propose them for hybridisation with cytotoxic payloads possessing a variety of chemical functionalities in order to specifically target tumours without affecting the healthy tissues Figure 11.59–63. Here, CA9 is linked to neoplasm.