TCRαβ/CD19 cell-depleted HLA-haploidentical transplantation to treat pediatric acute leukemia: updated final analysis

ABSTRACT

TCRαβ/CD19 cell depletion is a promising graft manipulation technique frequently used in the context of human leukocyte antigen (HLA)-haploidentical hematopoietic stem cell transplantation (HSCT). We previously reported the results of a phase I-II clinical trial (NCT01810120) to assess the safety and the efficacy of this type of exvivo T-cell depletion in 80 children with acute leukemia, showing promising survival outcomes. We now report an updated analysis on a cohort of 213 children with a longer follow-up (median, 47.6 months for surviving patients). With a 5-year cumulative incidence of nonrelapse mortality of 5.2% (95% confidence interval [CI], 2.8%-8.8%) and a cumulative incidence of relapse of 22.7% (95% CI, 16.9%-29.2%), projected 10-year overall and disease-free survival (DFS) were 75.4% (95% CI, 68.6%-80.9%) and 71.6% (95% CI, 64.4%-77.6%), respectively. Cumulative incidence of both grade II-IV acute and chronic graft-versus-host disease were low (14.7% and 8.1%, respectively). In a multivariable analysis for DFS including type of disease, use of total body irradiation in the conditioning regimen (hazard ratio [HR], 0.5; 95% CI, 0.26-0.98; P = .04), disease status at HSCT (complete remission [CR] ≥3 vs CR 1/2; HR, 2.23; 95% CI, 1.20-4.16; P = .01), and high levels of pre-HSCT minimal residual disease (HR, 2.09; 95% CI, 1.01-4.33; P = .04) were independently associated with outcome. In summary, besides confirming the good outcome results already reported (which are almost superimposable on those of transplant from HLA-matched donors), this clinical update allows the identification of patients at higher risk of treatment failure for whom personalized approaches, aimed at reducing the risk of relapse, are warranted.

T-cell depleted HLA-haploidentical HSCT in a child with neuromyelitis optica

Neuromyelitis optica is an immune-mediated disease characterized by a relapsing course, resulting in progressive disability. In children, given the long life expectancy, a disease-modifying treatment could be particularly desirable. Unfortunately, the currently available treatment strategies with this potential are scarce. Very limited data are available about the use of allogeneic hematopoietic stem cell transplantation (HSCT) for autoimmune neurological diseases. In this report, we present a pediatric case successfully treated with allogeneic HSCT from an HLA-haploidentical donor, after ex vivo TCR/CD19-depletion of the graft. To the best of our knowledge, this is the first case of a pediatric patient to benefit from such a treatment.

Long-term follow-up of IPEX syndrome patients after different therapeutic strategies: An international multicenter retrospective study

Background

Immunodysregulation polyendocrinopathy enteropathy x-linked(IPEX) syndromeis a monogenic autoimmune disease caused by FOXP3 mutations. Because it is a rare disease, the natural history and response to treatments, including allogeneic hematopoietic stem cell transplantation (HSCT) and immunosuppression (IS), have not been thoroughly examined.

Objective

This analysis sought to evaluate disease onset, progression, and long-term outcome of the 2 main treatments in long-term IPEX survivors.

Methods

Clinical histories of 96 patients with a genetically proven IPEX syndrome were collected from 38 institutions worldwide and retrospectively analyzed. To investigate possible factors suitable to predict the outcome, an organ involvement (OI) scoring system was developed.

Results

We confirm neonatal onset with enteropathy, type 1 diabetes, and eczema. In addition, we found less common manifestations in delayed onset patients or during disease evolution. There is no correlation between the site of mutation and the disease course or outcome, and the same genotype can present with variable phenotypes. HSCT patients (n = 58) had a median follow-up of 2.7 years (range, 1 week-15 years). Patients receiving chronic IS (n = 34) had a median follow-up of 4 years (range, 2 months-25 years). The overall survival after HSCT was 73.2% (95% CI, 59.4-83.0) and after IS was 65.1% (95% CI, 62.8-95.8). The pretreatment OI score was the only significant predictor of overall survival after transplant (P = .035) but not under IS.

Conclusions

Patients receiving chronic IS were hampered by disease recurrence or complications, impacting long-term disease-free survival. When performed in patients with a low OI score, HSCT resulted in disease resolution with better quality of life, independent of age, donor source, or conditioning regimen.

Preservation of Antigen-Specific Functions of αβ T Cells and B Cells Removed from Hematopoietic Stem Cell Transplants Suggests Their Use As an Alternative Cell Source for Advanced Manipulation and Adoptive Immunotherapy

Hematopoietic stem cell transplantation is standard therapy for numerous hematological diseases. The use of haploidentical donors, sharing half of the HLA alleles with the recipient, has facilitated the use of this procedure as patients can rely on availability of a haploidentical donor within their family. Since HLA disparity increases the risk of graft-versus-host disease, T-cell depletion has been used to remove alloreactive lymphocytes from the graft. Selective removal of αβ T cells, which encompass the alloreactive repertoire, combined with removal of B cells to prevent EBV-related lymphoproliferative disease, proved safe and effective in clinical studies. Depleted αβ T cells and B cells are generally discarded as by-products. Considering the possible use of donor T cells for donor lymphocyte infusions or for generation of pathogen-specific T cells as mediators of graft-versus-infection effect, we tested whether cells in the discarded fractions were functionally intact. Response to alloantigens and to viral antigens comparable to that of unmanipulated cells indicated a functional integrity of αβ T cells, in spite of the manipulation used for their depletion. Furthermore, B cells proved to be efficient antigen-presenting cells, indicating that antigen uptake, processing, and presentation were fully preserved. Therefore, we propose that separated αβ T lymphocytes could be employed for obtaining pathogen-specific T cells, applying available methods for positive selection, which eventually leads to indirect allodepletion. In addition, these functional T cells could undergo additional manipulation, such as direct allodepletion or genetic modification.

Strategies to accelerate immune recovery after allogeneic hematopoietic stem cell transplantation

The interplay existing between immune reconstitution and patient outcome has been extensively demonstrated in allogeneic hematopoietic stem cell transplantation. One of the leading causes of infection-related mortality is the slow recovery of T-cell immunity due to the conditioning regimen and/or age-related thymus damage, poor naïve T-cell output, and restricted T-cell receptor (TCR) repertoires. With the aim of improving posttransplantation immune reconstitution, several immunotherapy approaches have been explored. Donor leukocyte infusions are widely used to accelerate immune recovery, but they carry the risk of provoking graft-versus-host disease. This review will focus on sophisticated strategies of thymus function-recovery, adoptive infusion of donor-derived, allodepleted T cells, T-cell lines/clones specific for life-threatening pathogens, regulatory T cells, and of T cells transduced with suicide genes.

Longitudinal Evaluation of Immune Reconstitution and B-cell Function After Hematopoietic Cell Transplantation for Primary Immunodeficiency

PURPOSE

Hematopoietic cell transplantation (HCT) provides a curative therapy for severe forms of primary immunodeficiencies (PID). While the timing and extent of T-cell reconstitution following transplant for PID has been studied in depth, less is known about the kinetics of B-cell development and long-term restoration of humoral functions, which been often reported to be suboptimal after HCT.

METHODS

We studied longitudinally B-cell development and function in a cohort of 13 PID patients transplanted between 1997 and 2010, with a follow-up ranging from 0.7 to 15 years. Flow cytometric analysis of naïve and antigen-experienced B-cell subsets and in vitro functional responses to CpG were compared with data from healthy children and correlated with the degree of B-cell chimerism and in vivo antibody production.

RESULTS

We found that total memory B-cells count remained below normal levels for the first 2 years of follow up and progressively normalized. Switched memory B-cells (CD19+CD27+IgD-IgM-) were restored early and better than IgM memory B-cells (CD19+CD27+IgD+IgM+), which remained significantly reduced long-term. The recovery of memory B-cells correlated with good in vivo humoral function and normalization of CpG-response. A complete B-cell reconstitution was usually associated with donor B-cells chimerism and pre-transplant conditioning. Donor source and the underlying genetic defect represented also important variables.

CONCLUSION

Monitoring of phenotypic and functional changes on B-cells following HCT may prove clinically relevant to tailor patients' care. In particular the analysis of IgM memory and switched memory B-cells in addition to in vitro B-cells stimulation are recommended before Ig replacement therapy (IgRT) discontinuation.

Mobilization of healthy donors with plerixafor affects the cellular composition of T-cell receptor (TCR)-αβ/CD19-depleted haploidentical stem cell grafts

BACKGROUND

HLA-haploidentical hematopoietic stem cell transplantation (HSCT) is suitable for patients lacking related or unrelated HLA-matched donors. Herein, we investigated whether plerixafor (MZ), as an adjunct to G-CSF, facilitated the collection of mega-doses of hematopoietic stem cells (HSC) for TCR-αβ/CD19-depleted haploidentical HSCT, and how this agent affects the cellular graft composition.

METHODS

Ninety healthy donors were evaluated. Single-dose MZ was given to 30 'poor mobilizers' (PM) failing to attain ≥40 CD34+ HSCs/μL after 4 daily G-CSF doses and/or with predicted apheresis yields ≤12.0x106 CD34+ cells/kg recipient's body weight.

RESULTS

MZ significantly increased CD34+ counts in PM. Naïve/memory T and B cells, as well as natural killer (NK) cells, myeloid/plasmacytoid dendritic cells (DCs), were unchanged compared with baseline. MZ did not further promote the G-CSF-induced mobilization of CD16+ monocytes and the down-regulation of IFN-γ production by T cells. HSC grafts harvested after G-CSF + MZ were enriched in myeloid and plasmacytoid DCs, but contained low numbers of pro-inflammatory 6-sulfo-LacNAc+ (Slan)-DCs. Finally, children transplanted with G-CSF + MZ-mobilized grafts received greater numbers of monocytes, myeloid and plasmacytoid DCs, but lower numbers of NK cells, NK-like T cells and Slan-DCs.

CONCLUSIONS

MZ facilitates the collection of mega-doses of CD34+ HSCs for haploidentical HSCT, while affecting graft composition.

Immunological Outcome in Haploidentical-HSC Transplanted Patients Treated with IL-10-Anergized Donor T Cells

T-cell therapy after hematopoietic stem cell transplantation (HSCT) has been used alone or in combination with immunosuppression to cure hematologic malignancies and to prevent disease recurrence. Here, we describe the outcome of patients with high-risk/advanced stage hematologic malignancies, who received T-cell depleted (TCD) haploidentical-HSCT (haplo-HSCT) combined with donor T lymphocytes pretreated with IL-10 (ALT-TEN trial). IL-10-anergized donor T cells (IL-10-DLI) contained T regulatory type 1 (Tr1) cells specific for the host alloantigens, limiting donor-vs.-host-reactivity, and memory T cells able to respond to pathogens. IL-10-DLI were infused in 12 patients with the goal of improving immune reconstitution after haplo-HSCT without increasing the risk of graft-versus-host-disease (GvHD). IL-10-DLI led to fast immune reconstitution in five patients. In four out of the five patients, total T-cell counts, TCR-Vβ repertoire and T-cell functions progressively normalized after IL-10-DLI. These four patients are alive, in complete disease remission and immunosuppression-free at 7.2 years (median follow-up) after haplo-HSCT. Transient GvHD was observed in the immune reconstituted (IR) patients, despite persistent host-specific hypo-responsiveness of donor T cells in vitro and enrichment of cells with Tr1-specific biomarkers in vivo. Gene-expression profiles of IR patients showed a common signature of tolerance. This study provides the first indication of the feasibility of Tr1 cell-based therapy and paves way for the use of these Tr1 cells as adjuvant treatment for malignancies and immune-mediated disorders.

Concurrent search for unrelated cord and volunteer donor in high-risk acute lymphoblastic leukemia

To assess the effectiveness of the search for an unrelated donor on the outcome of patients with high-risk acute lymphoblastic leukemia, we analyzed prospectively 136 patients who underwent a search for cord blood (CB) and an unrelated volunteer donor (UD) at the same time. The probability of finding a donor was 58.2%, 70.3%, and 75.7% at 3, 6, and 12 months, respectively. The median time to find a donor was 1.8 months for CB and 3.5 months for UD. Of the 99 patients with a donor, 38.4% failed to undergo the transplant because of a relapse observed at a median of 4 months from the start of the search. In univariate analysis, absence of relapse during the search (p < 0.0001) and transplant (p = 0.004) showed a positive impact on long-term survival. In multivariate analysis, relapse during the search remained the key factor affecting survival (p < 0.0001). Since an extension of the search beyond 3 months enables only a slight increase in the probability of finding a donor compared to the increased risk of relapse, the time of the search should not exceed the 3-month time point. The simultaneous search for CB and UD increases the likelihood of performing a timely transplant.

Clinical tolerance in allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation (HSCT) has been a curative therapeutic option for a wide range of immune hematologic malignant and non-malignant disorders including genetic diseases and inborn errors. Once in the host, allogeneic transplanted cells have not only to ensure myeloid repopulation and immunological reconstitution but also to acquire tolerance to host human leukocyte antigens via central or peripheral mechanisms. Peripheral tolerance after allogeneic HSCT depends on several regulatory mechanisms aimed at blocking alloimmune reactivity while preserving immune responses to pathogens and tumor antigens. Patients transplanted with HSCT represent an ideal model system in humans to identify and characterize the key cellular and molecular players underlying these mechanisms. The knowledge gained from these studies has allowed the development of novel therapeutic strategies aimed at inducing long-term peripheral tolerance, which can be applicable not only in allogeneic HSCT but also in autoimmune diseases and solid-organ transplantation. In the present review, we describe Type 1 regulatory T cells, initially discovered and characterized in chimeric patients transplanted with human leukocyte antigen-mismatched HSCT, and how their presence correlates to tolerance induction and maintenance. Furthermore, we summarize different cell therapy approaches with regulatory T cells, designed to facilitate tolerance induction, minimizing pharmaceutical interventions.

Functional analysis and gene expression profile of umbilical cord blood regulatory T cells

The aim of the study was to analyze and compare the functional properties and the gene expression profile of regulatory T cells (Tregs) isolated from cord blood (CB) units (n = 23) and from the peripheral blood (PB) of adult normal donors (n = 13). Tregs were purified from mononuclear cells and expanded for 6 days with anti-CD3, anti-CD28, and IL-2. CB and PB Tregs presented similar immunophenotypic features. However, Tregs isolated from CB presented a much higher expansion capacity; this was confirmed by the genomic characterization that showed in CB-derived Tregs significant enrichments of genes involved in cell proliferation, chromatin modification, and regulation of gene expression. All samples were positive for the FoxP3 gene and protein after expansion. CB and PB expanded Tregs exerted a comparable and potent suppressive function on the proliferative reaction of autologous T cells stimulated by allogeneic dendritic cells and presented a high in vitro IL-10 production capacity. Gene profile analysis also revealed for PB Tregs significant enrichments of genes involved in the adaptive immune response. These data offer further insights into the understanding of the biology of CB transplantation indicating a possible role played by CB Tregs in the suppression of the allogeneic T cell response.

The immune reconstitution after an allogeneic stem cell transplant correlates with the risk of graft-versus-host disease and cytomegalovirus infection

Aim of the study was to correlate the clinical outcome of eighteen patients who have undergone an allogeneic stem cell transplant (SCT) with the concentration in the peripheral blood (PB) of lymphocyte subpopulations evaluated at 1 year from transplant. The occurrence of acute GVHD and CMV infection correlated with the concentration of Tregs in the PB; CMV infection also correlated with the content of NK cells. The obtained results document that the concentration of Tregs in the PB after an allogeneic SCT may protect from GVHD and from CMV infection; the potential anti-viral role of NK cells is confirmed.

Cell therapy with human T regulatory type 1 cells in allogeneic transplantations

Regulatory T cells (Tregs) are a specialized subset of T cells able to control immune responses and promote and maintain immune tolerance. Deficiency or defective function of Tregs has been correlated with autoimmunity, whereas their presence has been associated with tolerance. CD4+ Tregs have been classified into two major subsets according to their origin: the natural occurring Tregs, which develop in the thymus and are present in mice and healthy human individuals since birth, and the inducible Tregs that are generated in the periphery under different tolerogenic conditions. Among the inducible Tregs, the T regulatory type 1 (Tr1) cells represent one of the most extensively characterized subset. Tr1 cells develop in the periphery upon chronic antigen stimulation in the presence of IL-10 produced by tolerogenic antigen-presenting cells. Tr1 cells are characterized by the capacity to produce high levels of IL-10 in the absence of IL-4 and can suppress undesired immune responses mainly through cytokine-mediated mechanisms. However, we recently demonstrated that immunomodulatory activities of Tr1 cells reside not only in their ability to secrete suppressive cytokines but also in their property of cell-to-cell contact-dependent killing of target myeloid cells mediated by granzyme B and perforin. Tr1 cells are distinct from natural occurring Tregs since they are independent from FOXP3 expression for both their function and generation, as demonstrated by Tr1 cell identification in IPEX patients. The presence of Tr1 cells in vivo is associated with tolerance, whereas defects in Tr1 cells lead to autoimmune diseases or to chronic inflammation. In humans, we showed that both exogenous IL-10 or IL-10-derived from tolerogenic dendritic cells (DC-10) can be used to generate alloantigen-specific Tr1 cells in vitro suitable for cell therapy. Moreover, a homogeneous population of IL-10-producing T cells with Tr1-like phenotype and functions can be generated by transducing human CD4+ T cells with a lentiviral vector encoding for human IL-10. A cellular therapy protocol for the ex vivo use of IL-10 to induce alloantigen-specific unresponsiveness in donor-derived T cells for adoptive transfer in patients transplanted with haploidentical hematopoietic stem cells is being applied for patients with high-risk hematopoietic malignancies. In our clinical trial, donor T cells anergized in vitro in the presence of IL-10 are infused post-transplantation into the host with the ultimate goal of providing immune reconstitution with donor T cells that are anergic towards host antigens and contain precursors of host-specific Tr1 cells. This cellular therapy has proven to be safe and to provide immunoreconstitution associated, in most of the patients, with only moderate graft-versus-host disease (GVHD) at a cell dose that, if transferred untreated, would have caused severe acute GVHD. A similar approach could be also foreseen in the clinical setting of HLA-matched unrelated donor to prevent acute and chronic GVHD. Ad hoc experimental settings have been established using dendritic cells as antigen-presenting cells to induce anergy in the context of HLA-matched donors. These recently developed methods allowing the ex vivo induction of Tregs for in vivo infusion represent the first step toward an enlarged use of these cells as cellular therapy not only to inhibit GVHD after allogeneic hematopoietic stem cell transplantation, but also to other transplantation settings, or to re-establish tolerance in autoimmune or allergic diseases.

Prognostic impact of pre-transplantation transfusion history and secondary iron overload in patients with myelodysplastic syndrome undergoing allogeneic stem cell transplantation: a GITMO study

BACKGROUND

Transfusion-dependency affects the natural history of myelodysplastic syndromes. Secondary iron overload may concur to this effect. The relative impact of these factors on the outcome of patients with myelodysplastic syndrome receiving allogeneic stem-cell transplantation remains to be clarified.

DESIGN AND METHODS

We retrospectively evaluated the prognostic effect of transfusion history and iron overload on the post-transplantation outcome of 357 patients with myelodysplastic syndrome reported to the Gruppo Italiano Trapianto di Midollo Osseo (GITMO) registry between 1997 and 2007.

RESULTS

Transfusion-dependency was independently associated with reduced overall survival (hazard ratio=1.48, P=0.017) and increased non-relapse mortality (hazard ratio=1.68, P=0.024). The impact of transfusion-dependency was noted only in patients receiving myeloablative conditioning (overall survival: hazard ratio=1.76, P=0.003; non-relapse mortality: hazard ratio=1.70, P=0.02). There was an inverse relationship between transfusion burden and overall survival after transplantation (P=0.022); the outcome was significantly worse in subjects receiving more than 20 red cell units. In multivariate analysis, transfusion-dependency was found to be a risk factor for acute graft-versus-host disease (P=0.04). Among transfusion-dependent patients undergoing myeloablative allogeneic stem cell transplantation, pre-transplantation serum ferritin level had a significant effect on overall survival (P=0.01) and non-relapse mortality (P=0.03). This effect was maintained after adjusting for transfusion burden and duration, suggesting that the negative effect of transfusion history on outcome might be determined at least in part by iron overload.

CONCLUSIONS

Pre-transplantation transfusion history and serum ferritin have significant prognostic value in patients with myelodysplastic syndrome undergoing myeloablative allogeneic stem cell transplantation, inducing a significant increase of non-relapse mortality. These results indicate that transfusion history should be considered in transplantation decision-making in patients with myelodysplastic syndrome.

Unrelated cord blood transplant in children with high-risk acute lymphoblastic leukemia: a long-term follow-up

BACKGROUND AND OBJECTIVES

The aim of this single center study was to assess the impact of pre-transplant factors on long-term follow-up in young patients affected by high-risk acute lymphoblastic leukemia (ALL) who underwent an unrelated cord blood transplant (CBT). The conditioning regimens, graft-versus-host disease (GVHD) prophylaxis and supportive policies were uniform for all patients.

DESIGN AND METHODS

We analyzed the results of CBT performed in 30 patients, aged <18 years, affected by high risk ALL. As conditioning regimen, all patients received 12 Gy fractionated total body irradiation, etoposide, cyclophosphamide and horse anti-lymphocyte globulin. GVHD prophylaxis consisted of 6-methylprednisolone and cyclosporine A. RESULTS The cumulative incidence of engraftment was 93% (95% CI:0.85-0.93). The cumulative incidence of grade III-IV acute and chronic GVHD was 7% (95% CI:0.01-0.19) and 33% (95% CI: 0.17-0.64), respectively. The 9-year cumulative incidence of transplant-related mortality and relapse was 34% (95% CI:0.13-0.45) and 31% (95% CI:0.16-0.61), respectively. The 9-year overall survival, leukemia-free survival and event-free survival were 42% (95% CI:0.52-0.93), 47% (95% CI:0.25-0.61) and 46% (95% CI:0.33-0.61), respectively. A number of CFU-GM <1 x 10(4)/Kg of recipient body weight was the only factor that negatively affected all outcome parameters both in univariate and multivariate analyses.

INTERPRETATION AND CONCLUSIONS

The infused cell dose expressed as in vitro progenitor cell growth represents the most important pre-transplant factor affecting the long-term outcome after an unrelated CBT in young patients with high risk ALL. The number of CFU-GM should thus be considered in the selection process of cord blood units for transplant.

New approach for bone marrow transplantation in patients with class 3 thalassemia aged younger than 17 years

When prepared for transplantation with busulfan (BU) 14 mg/kg and cyclophosphamide (CY) 120 to 160 mg/kg, patients with thalassemia in risk class 3, aged younger than 17 years, who receive transplants from HLA-identical donors, had a 30% incidence of transplant rejection with recurrence of thalassemia. This, relatively poor, outcome was ascribed to insufficient immune suppression or to inadequate eradication of the thalassemic marrow, or both. In an attempt to enhance both immune suppression and eradication of the thalassemic clones, hydroxyurea, azathioprine, and fludarabine were added to the BU and CY. This regimen, called protocol 26, was applied to 33 consecutive patients with class 3 thalassemia aged younger than 17 years and was well tolerated with 93% survival. The incidence of recurrent thalassemia after the transplantation decreased from 30% to 8%.