Potential targets have been identified to be targeted along with MMR deficiency: dihydrofolate reductase (DHFR), DNA polymerase β (POLβ), DNA polymerase γ (POLγ) and PTEN-induced putative kinase 1 (PINK1), all causing accumulation of oxidative DNA damage when inhibited and combined with MMR deficiency (MSH1-2-6) [208–210]. This evidence concerns the gene POLB and mismatch repair cancer syndrome 1.