Analyzing data from various clinical trials of PD-1/PD-L1 checkpoint blockade (sometimes in combination with CTLA-4 checkpoint blockade), Schalper and Carleton et al. found that IL-8 serves as an independent biomarker that predicts shorter survival and reduced clinical benefit from immunotherapy. Their data suggest that IL-8 likely recruits immunosuppressive myeloid cells like neutrophils and macrophages to tumors, resulting in tumor environments that exclude T cells and/or suppress T cell activation.
ABSTRACT: Serum interleukin-8 (IL-8) levels and tumor neutrophil infiltration are associated with worse prognosis in advanced cancers. Here, using a large-scale retrospective analysis, we show that elevated baseline serum IL-8 levels are associated with poor outcome in patients (n = 1,344) with advanced cancers treated with nivolumab and/or ipilimumab, everolimus or docetaxel in phase 3 clinical trials, revealing the importance of assessing serum IL-8 levels in identifying unfavorable tumor immunobiology and as an independent biomarker in patients receiving immune-checkpoint inhibitors.