Fig. 2.

Synthetic Lethality of PARP-inhibitors in BRCA Tumors. Poly(ADP-ribose) polymerases (PARPs) repair DNA SSBs through the BER pathway. PARP inhibitors, such as olaparib, prevent repair of the SSBs, resulting in the generation of DNA DSBs. Cancer cells with a deficient homologous recombination (BRCA1/BRCA2 mutations) required for the repair of the DSBs do not compensate for the increased DNA damage caused by the inhibition of PARP enzymes and appear to be especially sensitive to treatment with these drugs