CXCR4/CXCL12 Activities in the Tumor Microenvironment and Implications for Tumor Immunotherapy

CXCR4 is a G-Protein coupled receptor that is expressed nearly ubiquitously and is known to control cell migration via its interaction with CXCL12, the most ancient chemokine. The functions of CXCR4/CXCL12 extend beyond cell migration and involve the recognition and disposal of unhealthy or tumor cells. The CXCR4/CXCL12 axis plays a relevant role in shaping the tumor microenvironment (TME), mainly towards dampening immune responses. Notably, CXCR4/CXCL12 cross-signal via the T and B cell receptors (TCR and BCR) and co-internalize with CD47, promoting tumor cell phagocytosis by macrophages in an anti-tumor immune process called ImmunoGenic Surrender (IGS). These specific activities in shaping the immune response might be exploited to improve current immunotherapies.