Correlative studies examining changes in T-cell subsets and T-cell clones in relation to CART19 cell infusion and pembrolizumab infusion. (A) Percentage of CART19⁺CD3⁺ cells in peripheral blood. Percentage of CART19⁺ of CD3⁺ cells prior to CART19 infusion (pre), 3 days after CART19 infusion (day 3), 7 days after CART19 (day 7), 10 days after CART19 (day 10), 14 days after CART19 (day 14), 26 days after CART19 and 1 hour after pembrolizumab infusion (day 26), 27 days after CART19 and 1 day after pembrolizumab (day 27), 28 days after CART19 and 2 days after pembrolizumab (day 28), and 45 days after CART19 and 14 days after pembrolizumab (day 45). (B) Fold change from baseline in IL-6 serum levels. (C) Percentage of PD1⁺CD4⁺ cells and PD1⁺Eomes⁺CD4⁺ cells in peripheral blood. (D) Percentage of PD1⁺CD4⁺CART19⁺ cells and PD1⁺Eomes⁺CD4⁺CART19⁺ cells in peripheral blood. (E) Percentage of PD1⁺CD8⁺ cells and PD1⁺Eomes⁺C8⁺ cells in peripheral blood. (F) Percentage of PD1⁺CD8⁺CART19⁺ cells and PD1⁺Eomes⁺CD8⁺CART19⁺ cells in peripheral blood. (G) Changes in T-cell clones as determined by TCRβ deep sequencing (Adaptive Biotechnologies, immunoSEQ).