Since IPMS causes MGMT-resistant O6-isopropyl dG and potential BER substrates such as N7-isopropyl dG and N3-isopropyl dA, co-treatment of IPMS and PARP inhibitor could cause synthetic lethality in HR-deficient tumor cells due to accumulation of DSBs caused by O6-isopropyl dG and induced by PARP1-DNA strand break complex during DNA replication. The gene discussed is PARP1; the disease is neoplasm.