Interleukin-10 Anergized Donor T Cell Infusion Improves Immune Reconstitution without Severe Graft-Versus-Host-Disease After Haploidentical Hematopoietic Stem Cell Transplantation.

Abstract 45

Background: Adoptive transfer of regulatory T cells is a potentially attractive alternative to conventional immunosuppressive therapy in allogeneic hematopoietic stem cell transplantation (HSCT) (Roncarolo MG., Nat Rev Immunol 2007). Among CD4+ T cells, the subset known as Type 1 regulatory T (Tr1) cells are induced in an antigen specific manner by interleukin-10 (IL-10) and suppress via production of high levels of IL-10 (Groux H., Nature 1997). The aim of this phase I/II study was to establish the safety and efficacy of a new cellular therapy with Tr1 cells in a non-randomized study.

Patients and Methods: A cellular therapy protocol for the adoptive transfer of IL-10 induced alloantigen specific donor-derived Tr1 cells in patients transplanted with CD34+ selected cells from haploidentical donor, has been applied to patients with high risk hematopoietic malignancies (www.risetfp6.org). Donor T cells, anergized ex vivo toward host alloantigens, presented by monocytes (original protocol) or tolerogenic dendritic cells (modified protocol) as host antigen presenting cells, in the presence of IL-10, are infused post-transplant into the host (IL-10 DLI). The infusion is made in the absence of immunosuppression for graft-versus-host-disease (GVHD) prophylaxis, with the ultimate goal to provide immune reconstitution without severe GVHD. The infused donor T cells, at the dose of 10⁵ CD3+ cells/kg or 3 × 10⁵ CD3+ cells/kg, are anergic towards host-HLA antigens and contain precursors of host-specific Tr1 cells but, at the same time, comprise memory T cells able to respond to nominal and viral antigens.

Results: Eighteen patients have been enrolled, sixteen received CD34+ selected cells from haploidentical donor after myeloablative conditioning. Twelve patients have been treated with IL-10 anergized cell therapy at day +30 post transplant, at the dose of 10⁵ CD3+ cells/kg with the exception of two patients who received 3 × 10⁵ CD3+ cells/kg. No severe immediate reactions post infusion were registered. Five patients died from infections by day +30 after Tregs cell infusion and two patients dropped out for graft rejection. Five patients achieved immune reconstitution at a median of 30,5 days (range 15–46 days) after IL-10 DLI, followed by progressive normalization of TCR repertoire, memory/naïve phenotype and T cell functions in vitro and in vivo. Acute GVHD grade III was observed in one patient who received 3 × 10⁵ CD3+ cells/kg; GVHD grade II was observed in 4 patients who received 10⁵ CD3+ cells/kg and were successfully immune reconstituted. The median follow-up of the IL-10 DLI treated patients is 980 days (range 291–1624); 4 patients are alive and disease free and they do not require immunosuppressive treatment.

Conclusions: Cellular therapy with IL-10 anergized donor T cells has proven to be safe and feasible, and to sustain immune reconstitution associated with a reduced severity of GVHD and no occurrence of relapse. This trial represents the first step towards an extended use of Tr1 cells as adjuvant treatment in allogeneic HSCT.