CXCR2 is expressed in primary AML and MDS samples and is associated with worse clinical outcomes. Expression of (A) chemokine ligands and (B) receptors was evaluated in the TCGA RNA-seq dataset from 200 AML samples (data shown as boxplots). (C) Median overall survival of AML patients with high CXCR2 was significantly worse than in patients with lower expression (log rank, P = .003). (D) Gene expression data of CD34⁺ cells from 183 MDS patients and 17 healthy controls shows significantly higher expression of CXCR2 in MDS CD34⁺ cells (t test, P < .001, FDR < 5%). MDS patients with (E) high CXCR2 expression (>median) have lower hemoglobin levels (t test, P < .001) and (F) higher RBC transfusion dependence (test of proportions, P < .05).