A phase I study of CD25/regulatory T-cell-depleted donor lymphocyte infusion for relapse after allogeneic stem cell transplantation

Abstract

Donor lymphocyte infusions are used to treat relapse after allogeneic hematopoietic stem cell transplantation, but responses are inadequate. In addition to effector cells, infusions contain CD25+ regulatory T cells (Treg) that may suppress graft-versus-tumor responses. We undertook a phase I study of donor lymphocyte infusions depleted of CD25+ T cells in patients with hematologic malignancies who had relapsed after transplantation. Twenty-one subjects received CD25/Treg-depleted infusions following removal of CD25+ cells using antibody-conjugated magnetic beads. Sixteen subjects received prior cytoreductive therapy. Four were in complete remission at the time of infusion. Two dose levels were administered: 1×107 (n=6) and 3×107 CD3+ cells/kg (n=15). A median 2.3 log-depletion of CD4+CD25+FOXP3+ Treg was achieved. Seven subjects (33%) developed clinically significant graft-versus-host disease by 1 year, including one patient who died. At dose level 1, five subjects had progressive disease and one had stable disease. At dose level 2, nine subjects (60%) achieved or maintained responses (8 complete responses, 1 partial response), including seven with active disease at the time of infusion. A shorter period between relapse and infusion was associated with response at dose level 2 (P=0.016). The 1-year survival rate was 53% among patients treated with dose level 2. Four of eight subjects with acute myeloid leukemia remained in remission at 1 year. When compared to unmodified donor lymphocyte infusions in 14 contemporaneous patients meeting study eligibility, CD25/Treg depletion was associated with a better response rate and improved event-free survival. Circulating naïve and central memory CD4+ T cells increased after CD25/Treg-depleted infusion, but no immunophenotypic signature for response was noted. CD25/Treg-depleted donor infusion appears feasible and capable of inducing graft-versus-tumor responses without excessive graft-versus-host disease. (ClinicalTrials.gov NCT#00675831).

Trial registration: ClinicalTrials.gov NCT00675831.

Copyright© Ferrata Storti Foundation.

Figures

Figure 1.

Flow cytometric analysis of CD4+CD25+FoxP3+ cells confirms Treg depletion. The initial apheresis product (top plots) and target fraction after CD25 depletion using the CliniMACS system (bottom plots) were subjected to extracellular staining for CD4 and CD25 expression and intracellular staining for FoxP3 protein. As shown for a representative DLI product, gating on CD45+CD4+ cells demonstrated reduction in cells expressing high levels of CD25 (left plots). Gating on CD4+CD25high cells demonstrated reduction in cells expressing FoxP3 (right plots) after the depletion process.

Figure 2.

Clinical outcomes after CD25/Treg-depleted DLI at dose level 2. (A) Kaplan Meier curves demonstrating overall survival after infusion for recipients of CD25/Treg-depleted DLI at 3×107 CD3+/kg (solid line) versus unmanipulated DLI at cell doses of 2.2–3.7×107 CD3+/kg (dotted line). (B) Kaplan Meier curves demonstrating improved event-free survival after CD25/Treg-depleted DLI (solid line) versus unmanipulated DLI (dotted line). (C) Relapse and non-relapse mortality: plot displaying cumulative incidences of disease relapse and non-relapse mortality after CD25/Treg-depleted DLI (solid and fine dotted lines, respectively) versus unmanipulated DLI (hashed and coarse dotted lines, respectively).

Figure 3.

Naïve and central memory cells increase within CD4+ and CD8+ T-cell compartments after CD25/Treg-depleted DLI. Peripheral blood mononuclear cells drawn at indicated times were stained for extracellular markers and analyzed by flow cytometry. (A) Changes in median distribution of CD4+ T cells among all subjects: the percentage of CD3+CD4+ T cells in each subset just prior to (0 months) or in the first 2 months after DLI is indicated. Panels reflect percentage of naïve cells (CD45RO-CD62L+), central memory cells (CD45RO+CD62L+), effector memory cells (CD45RO+CD62L−), and terminal effectors (CD45RO−CD62L−). *Indicates P<0.05 for the comparison between baseline (month 0) and the indicated time point. (B) Changes in median distribution of CD8+ T cells. Individual CD8+ subsets and significant differences among all subjects after CD25/Treg-depleted DLI are displayed as detailed above.