Prophylactic transfer of CD8-depleted donor lymphocytes after T-cell-depleted reduced-intensity transplantation

Donor lymphocyte infusions for acute myeloid leukaemia

The success of donor lymphocyte infusion (DLI) in treating chronic myeloid leukaemia that had recurred after allogeneic haematopoietic stem cell transplantation provided direct evidence for the existence of an immunologically mediated graft-vs-leukaemia effect and led to the development of non-myeloablative transplantation. For patients with acute myeloid leukaemia (AML), DLI has been less effective, both as a result of its rapid growth kinetics and its decreased susceptibility to alloimmune-mediated effects. This chapter reviews the historical experience with DLI for AML, both as treatment for and prophylaxis of relapse. New approaches aimed at improving the efficacy of DLI are discussed, including administration of chemotherapy prior to DLI, use of immunomodulatory cytokines to bolster the cytotoxic effector response, priming of donor lymphocytes to recipient tumour antigens ex vivo, and infusions of alloreactive natural killer cells.

The programmed death (PD)-1/PD-ligand 1 pathway regulates graft-versus-host-reactive CD8 T cells after liver transplantation

Acute graft-versus-host disease (aGVHD) is a life-threatening complication after solid-organ transplantation, which is mediated by host-reactive donor T cells emigrating from the allograft. We report on two liver transplant recipients who developed an almost complete donor chimerism in peripheral blood and bone marrow-infiltrating T cells during aGVHD. By analyzing these T cells directly ex vivo, we found that they died by apoptosis over time without evidence of rejection by host T cells. The host-versus-donor reactivity was selectively impaired, as anti-third-party and antiviral T cells were still detectable in the host repertoire. These findings support the acquired donor-specific allotolerance concept previously established in animal transplantation studies. We also observed that the resolution of aGVHD was not accompanied by an expansion of circulating immunosuppressive CD4/CD25/FoxP3-positive T cells. In fact, graft-versus-host-reactive T cells were controlled by an alternative negative regulatory pathway, executed by the programmed death (PD)-1 receptor and its ligand PD-L1. We found high PD-1 expression on donor CD4 and CD8 T cells. In addition, blocking PD-L1 on host-derived cells significantly enhanced alloreactivity by CD8 T cells in vitro. We suggest the interference with the PD-1/PD-L1 pathway as a therapeutic strategy to control graft-versus-host-reactive T cells in allograft recipients.

Graft-versus-host disease after donor leukocyte infusions: presentation and management

Donor leukocyte infusion (DLI) is used after both myeloablative and non-myeloablative stem-cell transplantation to treat and prevent relapse, to establish full donor chimerism, and to treat and prevent infections. The major treatment-related complication of DLI is graft-versus-host disease (GVHD). The presentation and treatment of GVHD after DLI is similar to its presentation and treatment after stem-cell transplantation, with some notable exceptions. While GVHD and graft-versus-tumor (GVT) effects are highly correlated after DLI, some patients experience remission without GVHD. Studies to define tumor-specific target antigens and GVT effector cells, as well as strategies of donor T-cell manipulation and optimization of DLI dose and schedule, may ultimately lead to the consistent ability to separate GVHD from GVT activity, improvement in the safety and specificity of DLI, and enhancement of the anti-tumor activity of donor T cells.

Prophylaxis of acute GVHD: manipulate the graft or the environment?

Graft-versus-host disease (GVHD) is the immune response of donor T lymphocytes responding to the recipient's alloantigens. The cellular and cytokine mechanisms driving GVHD are now well defined and have led to several prophylactic approaches. Selective allodepletion techniques promise to prevent GVHD without causing immune deficiency provoked by global T-cell depletion. Targeted dosing of other (non-T-cells) cells in the graft - such as CD34+ progenitors, regulatory T cells, natural killer cells and mesenchymal stromal cells - can also lead to transplants designed to retain immune capability without causing GVHD. Immunosuppressive drugs such as methotrexate, cyclosporine and anti-lymphocyte antibodies are the mainstay in the prevention of GVHD and can be used in conjunction with engineered grafts to eliminate GVHD. In future it is anticipated that further refinements in targeting the elimination or suppression of the GVHD reacting T cells should be selective enough to preserve the important graft-versus-leukemia effect which contributes to the cure of malignant diseases by allogeneic stem-cell transplantation.

Identification of phosphatidylinositol 4-kinase type II beta as HLA class II-restricted target in graft versus leukemia reactivity

Patients with hematological malignancies can be successfully treated with HLA-matched T cell-depleted allogeneic stem cell transplantation (alloSCT) and subsequent donor lymphocyte infusions (DLIs). The efficacy of DLI is mediated by donor T cells recognizing minor histocompatibility antigens (mHags) on malignant recipient cells. Because HLA class II molecules are predominantly expressed on hematopoietic cells, mHag-specific CD4(+) T cells may selectively mediate graft versus leukemia (GvL) reactivity without graft versus host disease (GvHD). In this study, we used a recombinant bacteria cDNA library for the identification of the first autosomal HLA class II (HLA-DQB1*0603)-restricted mHag LB-PI4K2B-1S encoded by the broadly expressed phosphatidylinositol 4-kinase type II beta gene. A polyclonal CD4(+) T cell response against LB-PI4K2B-1S was demonstrated in a patient with relapsed chronic myeloid leukemia (CML) who responded to DLI after HLA-matched alloSCT. LB-PI4K2B-1S-specific CD4(+) T cells recognized and lysed the CD34(+) CML cells of the patient and other leukemic cells as well as high HLA-DQ-expressing normal hematopoietic cells. HLA-DQ expression on normal cells of nonhematopoietic origin was moderately up-regulated by IFN-gamma and not sufficient for T cell recognition. We hypothesize that LB-PI4K2B-1S-specific CD4(+) T cells contributed to the antitumor response by both directly eliminating malignant cells as effector cells and stimulating CD8(+) T cell immunity as helper cells.

Reduced intensity conditioning for allogeneic hematopoietic stem cell transplantation in myelodysplastic syndromes and acute myelogenous leukemia

PURPOSE OF REVIEW

The aim of this article is to summarize the outcome in recent studies of patients with acute myelogenous leukemia/myelodysplastic syndromes after reduced intensity conditioning for allogeneic stem cell transplantation.

RECENT FINDINGS

Reduced intensity conditioning has demonstrated the capability to achieve engraftment and to decrease early nonrelapse mortality in older and unfit patients. Most large retrospective studies have demonstrated that reduced intensity conditioning regimens lead to a reduction of nonrelapse mortality in patients with acute myelogenous leukemia and myelodysplastic syndromes, but disease relapse is higher than with standard myeloablative conditioning regimens. Chronic graft-versus-host disease has emerged as one of the more powerful variables reducing relapses and improving overall and disease-free survival. The use of in-vivo T-cell depletion with alemtuzumab or antithymocyte globulin reduces acute graft-versus-host disease but appears to have no impact on survival. Hopefully, a new second generation of reduced intensity conditioning will study new strategies for reducing disease relapse with low nonrelapse mortality.

SUMMARY

Allogeneic stem cell transplantation with reduced intensity conditioning allows many patients considered ineligible for standard myeloablative conditioning to benefit from this therapy. Research must now focus on designing new strategies for reducing the increased risk of disease relapse.

Multiple myeloma patients receiving pre-emptive donor lymphocyte infusion after partial T-cell-depleted allogeneic stem cell transplantation show a long progression-free survival

The purpose of this study was to determine the role of pre-emptive donor lymphocyte infusion (pDLI) after partial T-cell-depleted allogeneic SCT in patients with multiple myeloma (MM). A cohort of 24 MM patients was treated with partial T-cell-depleted myeloablative SCT between December 1997 and April 2002. These patients were intended to receive pDLI after SCT. The overall response rate after SCT was 83% (20 of 24 patients) with 10 patients (42%) in complete remission (CR). Transplant-related mortality within 1 year after SCT was 29%. Thirteen patients (54%) received pDLI and four patients in partial remission reached CR. GVHD>grade I after pDLI developed in 4 out of 13 patients (30%). Four patients received therapeutic DLI, without preceding pDLI. Eleven patients (46%) are alive, with a median follow-up of 67 months (range, 48-100 months). Seven of these patients (29%) are in continuous CR (CCR), which was confirmed by a negative patient-specific IgH PCR in four patients. All seven patients in CCR received pDLI. Although myeloablative SCT in MM induces high toxicity, we show that the concept of T-cell depletion followed by pDLI is promising and needs to be investigated in a reduced-intensity conditioning setting.