Recent development in the discovery of PARP inhibitors as anticancer agents: a patent update (2016-2020).

The outstanding success demonstrated by the FDA approved PARP inhibitors has fueled further clinical evaluations for expansion of their clinical utilities. The current clinical investigations include new candidates as well as marketed PARP-targeted drugs, both as single agents and in combination with other chemotherapeutics. Recent advances have also unveiled critical roles of other PARPs in oncogenic signal transduction, in addition to those of the well-documented PARP1/2 and TNKS1/2 enzymes. Further studies on lesser-known PARP members are urgently needed for functional annotations and for understanding their roles in cancer progression and other human diseases.