Umbilical cord blood-derived T regulatory cells to prevent GVHD: kinetics, toxicity profile, and clinical effect

Abstract

We studied the safety and clinical outcomes of patients treated with umbilical cord blood (UCB)-derived regulatory T cells (Tregs) that expanded in cultures stimulated with K562 cells modified to express the high-affinity Fc receptor (CD64) and CD86, the natural ligand of CD28 (KT64/86). Eleven patients were treated with Treg doses from 3-100 × 10(6) Treg/kg. The median proportion of CD4(+)FoxP3(+)CD127(-) in the infused product was 87% (range, 78%-95%), and we observed no dose-limiting infusional adverse events. Clinical outcomes were compared with contemporary controls (n = 22) who received the same conditioning regimen with sirolimus and mycophenolate mofetil immune suppression. The incidence of grade II-IV acute graft-versus-host disease (GVHD) at 100 days was 9% (95% confidence interval [CI], 0-25) vs 45% (95% CI, 24-67) in controls (P = .05). Chronic GVHD at 1 year was zero in Tregs and 14% in controls. Hematopoietic recovery and chimerism, cumulative density of infections, nonrelapse mortality, relapse, and disease-free survival were similar in the Treg recipients and controls. KT64/86-expanded UCB Tregs were safe and resulted in low risk of acute GVHD.

Figure 1

(A) Logarithmic scale of the absolute number of nucleated cells after CD25⁺ immunomagnetic separation and at the end of the KT64/86-stimulated culture, of which the median proportion of CD4⁺CD25⁺ cells was 97% (range, 88-99) and with 87% (range, 78-95) expressing CD4⁺FoxP3⁺CD127^–. (B) The median proportion, interquartile range, and range of CD4⁺FoxP3⁺CD127^lowHelios⁺ cells that expressed the surface markers CD62L, OX40, and 41BB. (C) The median proportion, interquartile range, and range of chemokine receptors expression on CD4⁺FoxP3⁺CD127^lowHelios⁺ cells; CXCR3⁺ (Th1-like), CXCR3^–CCR6^– (Th2-like), CXCR3^–CCR4⁺CCR6⁺CCR10^– (Th17-like), and CXCR3^–CCR4⁺CCR6⁺CCR10⁺ (Th22-like). (D) The median proportion, interquartile range, and range of CD4⁺FoxP3⁺Helios⁺ cells that after ionophore and PMA stimulation expressed IFNγ, TNFα, IL-2, IL-4, IL-10, and IL-17. (E) The median proportion, interquartile range, and range of utilization of 24 v beta-chains in CD4⁺CD25⁺⁺ cells from the Treg product. (F) The proportion of CD4⁺FoxP3⁺CD127^low cells derived from the expansion product detected in the PB of the patients with an informative HLA marker (n = 7). The black lines on all panels represent the median values.

Figure 2

(A-C) Cumulative incidences of grade II-IV acute GVHD at day +100 (A), neutrophil recovery ≥500/μL by day +42 (B), and platelet recovery ≥20 000/μL at day +180 (C) for Treg recipients (solid line) and Siro/MMF controls (dotted line). (D) The density of infections at day +100 in Treg recipients (▪) and Siro/MMF controls (□).

Figure 3

(A-D) The absolute number of CD3⁺CD4⁺ (A) and CD4⁺CD45⁺CCR7⁺ (B) lymphocytes subsets at days +28, +60, +100, and +180 after transplantation for Treg recipients (gray square) and Siro/MMF controls (□). The cumulative incidence of NRM at 6 months (C) and the probability of disease-free survival at 1 year (D) for Treg recipients (solid line) and Siro/MMF controls (dotted line).