O-6-Benzylguanine is widely used in cancer research and therapy, particularly in modulating the activity of DNA repair proteins. It acts as an inhibitor of the DNA repair enzyme O6-alkylguanine-DNA alkyltransferase (AGT), also known as MGMT. This enzyme can repair DNA damage caused by alkylating agents, which are common in chemotherapy, thereby reducing the effectiveness of such treatments. By inhibiting AGT, O-6-Benzylguanine sensitizes tumor cells to alkylating drugs, enhancing their cytotoxic effects. It is especially valuable in studies involving drug-resistant tumors that overexpress MGMT. Researchers use it to overcome resistance and improve the efficacy of chemotherapeutic agents like temozolomide and carmustine. Due to this property, O-6-Benzylguanine has been investigated in clinical trials as a potential adjunct in the treatment of gliomas and other resistant cancers. Its role in targeted therapy makes it a key compound in developing strategies to improve outcomes in alkylating agent-based chemotherapy.