Interleukin-8 in cancer pathogenesis, treatment and follow-up

•IL-8 is a chemokine frequently produced in the tumor microenvironment by human malignant cells.•IL-8 plays key roles in the immunobiology of human malignancies and resistance to treatments.•Circulating IL-8 concentration reflects tumor burden.•Change in serum IL-8 is a biomarker to follow immunotherapy with checkpoint inhibitors. Interleukin-8 (CXCL8) was originally described asa chemokine whose main function is the attraction of a polymorphonuclear inflammatory leukocyte infiltrate acting on CXCR1/2. Recently, it has been found that tumors very frequently coopt the production of this chemokine, which in this malignant context exerts different pro-tumoral functions. Reportedly, these include angiogenesis, survival signaling for cancer stem cells and attraction of myeloid cells endowed with the ability to immunosuppress and locally provide growth factors. Given the fact that in cancer patients IL-8 is mainly produced by tumor cells themselves, its serum concentration has been shown to correlate with tumor burden. Thus, IL-8 serum concentrations have been shown to be useful asa pharmacodynamic biomarker to early detect response to immunotherapy. Finally, because of the roles that IL-8 plays in favoring tumor progression, several therapeutic strategies are being developed to interfere with its functions. Such interventions hold promise, especially for therapeutic combinations in the field of cancer immunotherapy.