Ongoing clinical trials are assessing the efficacy of rucaparib alone or in combination with other cytotoxic drugs, mainly in breast and ovarian cancer patients with mutations in the breast cancer associated (BRCA) genes.We aimed to establish whether the multidrug efflux transporters ABCG2 (BCRP) and ABCB1 (P-gp, MDR1) affect the oral availability and brain penetration of rucaparib in mice.In vitro, rucaparib was efficiently transported by both human ABCB1 and ABCG2, and very efficiently by mouse Abcg2