One concept is to irreversibly inactivate MGMT through administration of O6-Benzylguanine, a compound that reacts with MGMT by covalent transfer of the benzyl group to the active site-cysteine and renders by this way the tumor cells 2- to 14-fold more sensitive to alkylating agents in vitro and in vivo settings [29] and phase II trials to prove the potential benefit of a combination of O6-Benzylguanine with temozolomide or BCNU are currently under way [24]. The gene discussed is MGMT; the disease is neoplasm.