Serum levels of IL15 (A), Flt-3L (B), and CX3CL1/fractalkine (C) obtained prior to transgenic TCR T-cell infusions were all significantly greater in clinical responders to therapy (n = 17) compared to non-responders (n = 10). All box and whisker plots represent median at dividing line, with interquartile range represented by boxes, and lines representing minimum and maximum values for each dataset, and are compared by unpaired t-test (*p<0.05), while all correlation plots represent Pearson’s r values. Each sample was run as an independent experiment, and data were aggregated by clinical response for analysis.