CXCR2 and neoplasm: Moreover, genetic and pharmacological inactivation of CXCR2, which is the major chemotactic receptor for PMN-MDSCs and neutrophils recruitment into tumors, was demonstrated to be effective in reducing tumor-infiltrating PMN-MDSCs and improving the response to anti-PD-1 in different pre-clinical model, such as head and neck [142] and colon [143] cancer.