PARP1 and cancer: In fact, in recent years, the success of poly(ADP ribose) polymerase inhibitors (PARPi): small molecules that inhibit the molecular and cellular function of PARP-1 and in doing so exploits the synthetic lethal relationship between PARP and BRCA1 or BRCA2 in BRCA1/2-null (ovarian or breast) tumors in response to platinum-based chemotherapy has made chemically induced synthetic lethality more mainstream in the development of new generation anti-cancer drugs [25,26].