PARP1 and breast cancer: It was observed that when matched biopsies from breast cancer patients who developed the disease while taking palbociclib and the samples from their initial biopsies (before treatment with palbociclib), it was uncovered that DNA repair, ER, and IL-6/STAT3 were dysregulated; therefore, the authors proposed that this resistance might be overcome by using PARP and STAT3 inhibitors[46].