When investigating the plasma concentration of the CXCR3 ligands CXCL9 and CXCL10 in tumor patients treated with anti-PD-1 alone or anti-PD-1 and anti-CTLA-4 antibodies, it was found that the treatment responder group has elevated levels within the first few months after therapy. The gene discussed is PDCD1; the disease is neoplasm.