CXCR4 and osteosarcoma: Importantly, of these IC’s targeted by plerixafor, IC-3 and IC-6 constitute the peritumoral microenvironment of each specimen which is hallmarked by a myeloid immune suppression transcriptional program (Supplemental Figure 1).35,36 To determine the clinical significance of these findings, we investigated the association between CXCR4 expression and outcome of patients with osteosarcoma.