CXCR2 and neoplasm: We next administered a CXCR2 inhibitor (CXCR2i) to patients with mCRPC progressing after at least one ARSI in an investigator-initiated clinical trial, to generate proof-of-mechanism data showing that CXCR2i can reduce peripheral and tumour myeloid infiltration, as well as to pursue proof-of-concept evidence that inhibition of myeloid infiltration can reverse clinical ARSI resistance.