When two TNBC breast cancer cell lines with BRCA mutations were co-cultured with T cells, the apoptosis rate in the combination group of PARP inhibitor Niraparib and NPC1L1 inhibitor Ezetimibe was 1.5 times that of the Niraparib monotherapy group, indicating that inhibition of NPC1L1 enhances the immune effect of PARP inhibitors. The gene discussed is PARP1; the disease is breast carcinoma.