CXCR2 antagonist 3 (compound 11h) is a potent antagonist of CXC chemokine receptor 2 ( CXCR2 ). CXCR2 antagonist 3 demonstrates double-digit nanomolar potencies against CXCR2 and significantly inhibited neutrophil infiltration into the air pouch. CXCR2 antagonist 3 reduces the infiltration of neutrophils and MDSCs and enhance the infiltration of CD3 + T lymphocytes into the Pan02 tumor tissues.