CGAS and neoplasm: The rationale for PARP inhibitors in combination with ICIs mainly involves four aspects as discussed below: (1) tumour mutation burden and enhanced neoantigen production; (2) upregulation of PD-L1 and cyclic GMP-AMP synthase-stimulator of interferon (cGAS-STING) pathway (3) reprograming of immune cells involved in tumour microenvironment (TME); (4) increasing tumour-infiltrating lymphocytes [43].