O-6-Benzylguanine is primarily used in biomedical research as a potent inhibitor of the DNA repair protein O-6-alkylguanine-DNA alkyltransferase (AGT). This protein plays a crucial role in repairing DNA damage caused by alkylating agents, which are often used in chemotherapy. By inhibiting AGT, O-6-Benzylguanine enhances the effectiveness of alkylating chemotherapeutic drugs, making it a valuable tool in cancer treatment strategies. It is particularly useful in sensitizing tumor cells to therapies that involve alkylating agents, thereby improving therapeutic outcomes. Additionally, it is employed in laboratory studies to investigate DNA repair mechanisms and to develop targeted cancer therapies.