Acute GVHD did not correlate with duration of PAC therapy, depth of pSTAT3 inhibition, or T-cell subsets. (A-C) Percentage (%) of pSTAT3⁺ CD4⁺ T cells at day +21 among patients treated on phase 2 PAC/SIR/TAC based on presence or absence of grade II to IV acute GVHD by day +100 (A), grade II to IV acute GVHD by day +30 (B), or use of systemic immune suppression (IS) beyond PAC/SIR/TAC to treat grade II to IV acute GVHD (C). (D-G) %CD4⁺ Th1 (D), Th2 (E), Th17 (F), or Treg (G) cells at day +21 among patients treated on phase 2 PAC/SIR/TAC based on presence of absence of grade II to IV acute GVHD by day +100. (H) Treg:Th1 + Th17 ratio at day +21 among patients without or with grade II to IV acute GVHD. NS, not significant.