a, Expression of IL18BP transcripts in normal (blue) or cancer (red) tissues from the TCGA database. CHOL, cholangiocarcinoma; DLBC, diffuse large B cell lymphoma; GBM, glioblastoma multiforme; HSNC, head and neck squamous carcinoma; KIRC, kidney renal clear cell carcinoma; PAAD, pancreatic adenocarcinoma; SKCM, skin cutaneous melanoma; STAD, stomach adenocarcinoma (*P < 0.01). b–d, Correlation of IL18BP expression with T cell markers CD3E (b), CD8A (c) and PDCD1 (d) from the TCGA database for SKCM (n = 558), BRCA (breast adenocarcinoma, n = 1,085), HNSC (n = 44), STAD (n = 221), and OV (ovarian cancer, n = 426). e, Frequency of IL-18BP immunohistochemistry staining levels in human tumour tissue microarrays. Each sample was scored as negative (0) or positive (1+, 2+, or 3+). Representative images are shown for each staining level. f, Quantification of plasma IL-18BP protein level by ELISA for healthy donors (n = 22) and patients with NSCLC (n = 52) at baseline before treatment and at the time of the following CT scan after receiving treatment with anti-PD-(L)1 (n = 52). g, Representative mean tumour growth in wild-type (left) and Il18bp−/− (right) mice engrafted s.c. with MC38 tumours and treated with PBS or IL-18. Data are representative of three independent experiments with n = 5 mice per group. P values were calculated using one-way ANOVA (a, f) or two-way ANOVA (g), and data are presented as mean ± s.e.m.