CXCR2 and breast cancer: Furthermore, a CXCR4 antagonist (AMD3100) prevents macrophage accumulation and delays tumor relapse after cyclophosphamide treatment in subcutaneously transplanted lung cancer and in orthotopic mammary cancers [46], and a CXCR2 (SB-265610) antagonist enhances therapeutic effect of a doxorubicin/cyclophosphamide combination treatment in a orthotopic breast cancer xenograft model probably through inhibition of myeloid cell accumulation [47].