Olaparib as a single agent is widely used in BRCA1 or BRCA2 mutant tumor cells, but had less effect in CCA cells without BRCA1 or BRCA2 mutations, with a half maximal inhibitory concentration (IC50) close to 10 μmol/L (Fig. 1a). The gene discussed is BRCA1; the disease is cholangiocarcinoma.