Anticancer carbonic anhydrase inhibitors: a patent and literature update 2018-2022

Introduction Cancer affects an increasing number of patients each year with an unacceptable death toll worldwide. A new therapeutic approach to combat tumors consists in targeting human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms IX and XII, which are tumor-associated, overexpressed enzymes in hypoxic tumors, being involved in metabolism, pH regulation, ferroptosis, and overall tumor progression. Areas covered Small molecule hCA IX/XII and antibody drug conjugate inhibitors targeting the two enzymes and their applications in the management of cancer are discussed. Expert opinion The available 3D crystal structures of hCA IX, XII as well as the off target isoforms hCA I and II, afforded structure-based drug design opportunities, which led to the development of various isoform-selective small molecule inhibitors belonging to diverse classes (sulfonamides, sulfamates, benzoxaboroles, selenols, coumarins, sulfocoumarins, and isocoumarins). Many patents focused on small inhibitors containing sulfonamide/sulfamide/sulfamide derivatives as well as hybrids incorporating sulfonamides and different antitumor chemotypes, such as cytotoxic drugs, kinase/telomerase inhibitors, P-gp and thioredoxin inhibitors. The most investigated candidate belonging to the class is the sulfonamide SLC-0111, in Phase Ib/II clinical trials for the management of advanced, metastatic solid tumors.