In addition, similarly to PARP1 or DNA polymerase Polθ inhibitors that are used to treat HR-deficient cancers [77–79], the small molecule JE-RH-06 disrupts the interaction between the TLS polymerases REV1 and Polζ and shows preferential cytotoxicity in BRCA1-deficient cancer cells [76,80]. This evidence concerns the gene BRCA1 and cancer.