Resumen:
Interleukin-8 (CXCL8) produced in the tumor microenvironment correlates with poor response to checkpoint inhibitors and is known to chemoattract and activate immunosuppressive myeloid leukocytes. In human cancer, IL8 mRNA levels correlate with IL1B and TNF transcripts. Both cytokines induced IL-8 functional expression from a broad variety of human cancer cell lines, primary colon carcinoma organoids, and fresh human tumor explants. Although IL8 is absent from the mouse genome, a similar murine axis in which TNF alpha and IL-1 beta upregulate CXCL1 and CXCL2 in tumor cells was revealed. Furthermore, intratumoral injection of TNF alpha and IL-1 beta induced IL-8 release from human malignant cells xenografted in immunodeficient mice. In all these cases, the clinically used TNF alpha blockers infliximab and etanercept or the IL-1 beta inhibitor anakinra was able to interfere with this pathogenic cytokine loop. Finally, in paired plasma samples of patients with cancer undergoing TNF alpha blockade with infliximab in a clinical trial, reductions of circulating IL-8 were substantiated. SIGNIFICANCE IL-8 attracts immunosuppressive protumor myeloid cells to the tumor microenvironment, and IL-8 levels correlate with poor response to checkpoint inhibitors. TNF alpha and IL-1 beta are identified as major inducers of IL-8 expression on malignant cells across cancer types and models in a manner that is druggable with clinically available neutralizing agents.
