FIGURE 1 from Activating Inducible T-cell Costimulator Yields Antitumor Activity Alone and in Combination with Anti-PD-1 Checkpoint Blockade

ICOS serves as a T-cell activation biomarker. A, Percentage expression of ICOS on T-cell subsets from healthy human donor PBMC following primary stimulation (day 0) and restimulation (day 8) using plate-coated anti-CD3/CD28 and flow cytometry (nonspecific binding was blocked with human or mouse Fc block). Data represent the mean ± SD of n = 4 samples; for gating strategy see Supplementary Fig. S1. B, TCGA-derived gene expression analysis of ICOS, ICOSLG (ICOS-LG), and PD-L1 (CD274) and Pearson correlation (r) analysis of ICOS versus PD-L1 (CD274) in different tumor types. Expression values were obtained from TCGA RNA-seq analysis. For heat map visualization, gene expression values obtained from TCGA were normalized within each indication using robust center scaling. Pearson correlation, significance, and number of tumors analyzed per indication can be found in Supplementary Table S5. Tumors were sorted on the basis of ICOS mRNA expression values from high to low. C, Violin plots showing expression of ICOS (log₂ TPM) in various T-cell subsets from HNSCC, melanoma, and NSCLC RNA-seq data sets (26–28). D and E, ICOS expression on freshly dissociated patient TILs using flow cytometry (nonspecific binding was blocked with human or mouse Fc block). D, Mean fluorescence intensity (log₁₀ MFI) of ICOS on individual T-cell populations. Median ICOS expression for each population is indicated by the horizontal bar with each symbol representing an individual patient (n = 1–6 samples/cancer type). For raw data and gating strategy, please see Supplementary Table S2 and Supplementary Fig. S2. E, Histograms of ICOS expression and isotype control on tumor-infiltrating T cells from a representative patient with colorectal cancer. AC, adenocarcinoma (LUAD); CRC, colorectal cancer; HNSCC, head and neck squamous cell carcinoma; ICOS, inducible T cell costimulator; NSCLC, non–small-cell lung carcinoma; PBMC, primary human peripheral blood mononuclear cells; PD-L1, programmed death ligand-1; RCC, renal cell carcinoma; SC, squamous cell (LUSC); TCGA, The Cancer Genome Atlas; TIL, tumor-infiltrating lymphocyte.