334P Metabolic reprogramming of the tumor microenvironment in pleural mesothelioma highlights nucleotide metabolism–immune interactions

monocytes, macrophages, neutrophils, NK-cells, T-cells, B-cells and plasma cells and key immune markers (e.g.PD-L1, PD-1, CTLA4).Within-patient variability was assessed via coefficient of variation (SD/mean), while between-patient variability was assessed by ANOVA.Results: Within-patient variability of immune cell signatures and key immune markers was low (median CV < 0.050 across all markers), and substantially smaller than inter-patient variability.Housekeeping genes and innate immune cells showed lowest variability within patients (median CV < 0.025), while infiltration of adaptive immune cells including B-cells and plasma cells showed higher variability between regions (median CV < 0.100). Conclusions:Our findings suggest that at the transcriptomic level, immune infiltrate is relatively homogenous throughout the individual mesothelioma tumors.Immune cell types involved in the adaptive immune response (B-cells and plasma cells) show more variability within distal sites of a tumour.These results support the use of single-site biopsies for inference of immune infiltrate throughout the tumour.