CXCR2 and rhabdomyosarcoma: Preclinical studies have reported that CXCR2 inhibitors or anti-CXCR2 antibodies alleviate MDSCs-induced immunosuppression, thus improving the effects of anti-PD-1 therapy in rhabdomyosarcoma, pancreatic ductal adenocarcinoma, and colorectal cancer (Steele et al., 2016; Horn et al., 2020).