Moreover, AZD2281 is hard to go through the blood-brain barrier [9] and is a substrate of the drug transporter P-glycoprotein (P-gp) [11], further limiting its uses in some tumors, such as malignant glioma (a high proportion of which harbors HR defects due to PTEN mutations) and P-gp-overexpressed tumors. The gene discussed is PGP; the disease is malignant glioma.