Antithymocyte Globulin Plus G-CSF Combination Therapy Leads to Sustained Immunomodulatory and Metabolic Effects in a Subset of Responders With Established Type 1 Diabetes

Abstract

Low-dose antithymocyte globulin (ATG) plus pegylated granulocyte colony-stimulating factor (G-CSF) preserves β-cell function for at least 12 months in type 1 diabetes. Herein, we describe metabolic and immunological parameters 24 months following treatment. Patients with established type 1 diabetes (duration 4–24 months) were randomized to ATG and pegylated G-CSF (ATG+G-CSF) (N = 17) or placebo (N = 8). Primary outcomes included C-peptide area under the curve (AUC) following a mixed-meal tolerance test (MMTT) and flow cytometry. “Responders” (12-month C-peptide ≥ baseline), “super responders” (24-month C-peptide ≥ baseline), and “nonresponders” (12-month C-peptide < baseline) were evaluated for biomarkers of outcome. At 24 months, MMTT-stimulated AUC C-peptide was not significantly different in ATG+G-CSF (0.49 nmol/L/min) versus placebo (0.29 nmol/L/min). Subjects treated with ATG+G-CSF demonstrated reduced CD4+ T cells and CD4+/CD8+ T-cell ratio and increased CD16+CD56hi natural killer cells (NK), CD4+ effector memory T cells (Tem), CD4+PD-1+ central memory T cells (Tcm), Tcm PD-1 expression, and neutrophils. FOXP3+Helios+ regulatory T cells (Treg) were elevated in ATG+G-CSF subjects at 6, 12, and 18 but not 24 months. Immunophenotyping identified differential HLA-DR expression on monocytes and NK and altered CXCR3 and PD-1 expression on T-cell subsets. As such, a group of metabolic and immunological responders was identified. A phase II study of ATG+G-CSF in patients with new-onset type 1 diabetes is ongoing and may support ATG+G-CSF as a prevention strategy in high-risk subjects.

Combination Immunotherapy for Type 1 Diabetes

“…However, this follow-up study found subjects receiving ATG/G-CSF had reduced CD4 + T-cells and CD4 + /CD8 + T-cell ratio and increased natural killer cells, memory T-cells, and neutrophils (86). Additionally, Tregs were elevated after 6, 12, and 18 months, but not after 24 months (86). Taken together, these results suggest that ATG/G-CSF therapy leads to prolonged immunomodulatory effects and a larger clinical trial in recent-onset T1D is underway within the TrialNet Clinical Network (https://clinicaltrials.gov/ct2/show/NCT02215200).…”

“…HbA1c levels also tended to be lower at 6 months in those who received ATG/G-CSF (83). A two-year follow-up revealed no difference in C-peptide levels 24 months post-intervention (86). However, this follow-up study found subjects receiving ATG/G-CSF had reduced CD4 + T-cells and CD4 + /CD8 + T-cell ratio and increased natural killer cells, memory T-cells, and neutrophils (86).…”

“…A two-year follow-up revealed no difference in C-peptide levels 24 months post-intervention (86). However, this follow-up study found subjects receiving ATG/G-CSF had reduced CD4 + T-cells and CD4 + /CD8 + T-cell ratio and increased natural killer cells, memory T-cells, and neutrophils (86). Additionally, Tregs were elevated after 6, 12, and 18 months, but not after 24 months (86).…”

Combinatorial drug delivery approaches for immunomodulation

“…Combination therapy with anti-thymocyte globulin and GM-CSF has been shown to increase Treg frequency, alter DC pheno-types, and improve survival in mouse models of type 1 diabetes [124,125]. This combinatorial approach was validated when explored in clinical trials of type 1 diabetics, improving Treg frequency and preserving β-cell function compared to placebo controls [126,127]. While careful consideration should be given to therapies that completely ablate leukocyte subpopulations for fear of promoting systemic immunosuppression, there is growing evidence that suggests immunoablation in combination with immunomodulation can be a useful approach.…”

Targeting innate immunity to downmodulate adaptive immunity and reverse type 1 diabetes

“…In terms of human clinical trials, the vast majority have targeted adaptive immunity. G-CSF combination therapy has recently been tested in humans, where it was well tolerated 83. Both Aralast and Imatinib human T1D trials have been initiated, but the full results are not yet known 84.…”