ERCC1 and cancer: Notably, in many cancers with DDR defects, such as non-small-cell lung cancer (NSCLC) deficient in ERCC1 (excision repair cross-complementation group 1) or TNBC deficient in BRCA1, PARPi synergizes with IFN-γ to induce expression of programmed cell death ligand 1 (PD-L1) on the cell surface, thereby amplifying the effectiveness of immune checkpoint inhibitors (ICI) [146].