BRCA1 and neoplasm: However, in a mouse model of BRCA1-deficient, triple-negative breast cancer (TNBC), olaparib treatment had a dual effect on macrophages, with an antitumour effect due to inducing macrophage expression of co-stimulatory molecules (CD80) and activation markers (CD40), and a pro-tumour effect due to increasing the expression of immunosuppressive markers (e.g., programmed death ligand-1, PD-L1) and colony-stimulating factor 1 receptor (CSF1R) [26].