Ilaria Mariangela Scaglione, Chiara Bazzichetto, Michele Borghesani, Francesca Zacchi, Serena Eccher, Marco Sposito, Jessica Insolda, Elena Giontella, Elena Trevisani, A. Avancini, Daniela Tregnago, Sara Cingarlini, Sara Pilotto, Fabiana Conciatori, Lorenzo Belluomini, Michele Milella
Interleukin-8 (IL-8/CXCL8) drives tumor progression via CXCR1/2 signaling, promoting proliferation, invasion, angiogenesis, and recruitment of pro-tumoral immune and stromal cells. Accumulating clinical evidence indicates that elevated circulating or intratumoral IL-8 levels are consistently associated with adverse prognosis and reduced therapeutic benefit across principal solid tumors. In particular, IL-8 has emerged as a promising prognostic and predictive biomarker of resistance to immune checkpoint inhibitors. This review highlights its prognostic and predictive value across gastrointestinal, genitourinary, lung, melanoma, breast, ovarian, and head and neck cancers, and discusses strategies targeting IL-8 and the need for standardized, clinically actionable assays.