NRG1 and neoplasm: The downregulation of AR activity and AR-V7 signatures in tumours in which CD11b+HLA-DRloCD15−CD14− cell density decreased after treatment with CXCR2i is consistent with preclinical work showing that PMN-MDSCs drive AR signalling through IL-23, although PMN-MDSCs can make other paracrine factors including IL-6 and NRG1 (refs. 10,17).