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Allogeneic hematopoietic stem cell transplantation (HSCT) is the most effective treatment in eradicating high-risk acute myeloid leukemia (AML). Here, we present data from a novel HLA-haploidentical HSCT protocol that addressed the 2 remaining major unmet medical needs: leukemia relapse and chronic graft-versus-host disease (cGVHD). Fifty AML patients were enrolled in the study. The conditioning regimen included total body irradiation for patients up to age 50 years and total marrow/lymphoid irradiation for patients age 51 to 65 years. Irradiation was followed by thiotepa, fludarabine, and cyclophosphamide. Patients received an infusion of 2 × 106/kg donor regulatory T cells on day -4 followed by 1 × 106/kg donor conventional T cells on day -1 and a mean of 10.7 × 106 ± 3.4 × 106/kgpurified CD34+ hematopoietic progenitor cells on day 0. No pharmacological GVHD prophylaxis was administered posttransplantation. Patients achieved full donor-type engraftment. Fifteen patients developed grade ≥2 acute GVHD (aGVHD). Twelve of the 15 patients with aGVHD were alive and no longer receiving immunosuppressive therapy. Moderate/severe cGVHD occurred in only 1 patient. Nonrelapse mortality occurred in 10 patients. Only 2 patients relapsed. Consequently, at a median follow-up of 29 months, the probability of moderate/severe cGVHD/relapse-free survival was 75% (95% confidence interval, 71%-78%). A novel HLA-haploidentical HSCT strategy that combines an age-adapted myeloablative conditioning regimen with regulatory and conventional T-cell adoptive immunotherapy resulted in an unprecedented cGVHD/relapse-free survival rate in 50 AML patients with a median age of 53 years. This trial was registered with the Umbria Region Institutional Review Board Public Registry as identification code 02/14 and public registry #2384/14 and at www.clinicaltrials.gov as #NCT03977103., (© 2021 by The American Society of Hematology.)

Allogeneic hematopoietic cell transplantation from a human leukocyte antigen (HLA) haplotype mismatched donor (haploidentical transplantation) was not feasible for the treatment of hematologic malignancies until the early 1990s, due to the high risk of rejection and graft-versus-host disease (GVHD). The first successful protocol of haploidentical transplantation was based on a highly myeloablative and immunosuppressive conditioning regimen and the infusion of a "mega-dose" of T-cell-depleted hematopoietic stem cells. More than 90% of patients engrafted and <10% developed GVHD. The protocol did not include post-transplant immunosuppression, which favored the graft-versus-tumor effect mediated by alloreactive NK cells and residual alloreactive T cells. However, donor post-transplant immune reconstitution was slow with a high risk of infection-related mortality. More recently, T-cell-depleted haploidentical transplantation has become the platform for innovative cell therapies that aim to enhance T-cell immunity while preventing adverse reactions against host tissues. One strategy is adoptive immunotherapy with conventional T cells and regulatory T cells. Preclinical studies and clinical trials have proven that regulatory T cells control GVHD caused by co-infused conventional T cells while the graft-versus-tumor effect is retained. The use of regulatory T cells in the absence of any other form of immune suppression allowed for a conventional T cell-mediated full eradication of disease in the vast majority of high-risk acute leukemia patients.

In allogeneic hematopoietic stem cell transplantation, which is the major curative therapy for hematological malignancies, T cells play a key role in the development of graft-versus-host disease (GvHD). NOTCH pathway is a conserved signal transduction system that regulates T cell development and differentiation. The present review analyses the role of the NOTCH signaling as a new regulator of acute GvHD. NOTCH signaling could also represent a new therapeutic target for GvHD.

Purpose: We sought to determine whether the total body irradiation (TBI) schedule affected outcome in patients with acute leukemia in complete remission who received T cell-depleted allogeneic hematopoietic stem cell transplantation from HLA identical siblings., Methods and Materials: The study recruited 55 patients (median age, 48 years; age range, 20-66 years; 30 men and 25 women; 34 with acute myeloid leukemia and 21 with acute lymphoid leukemia). Hyperfractionated TBI (HTBI) (1.2 Gy thrice daily for 4 days [for a total dose of 14.4 Gy] from day -12 to day -9) was administered to 29 patients. Single-dose TBI (STBI) (8 Gy, at a median dose rate of 10.7 cGy/min on day -9) was given to 26 patients., Results: All patients achieved primary, sustained engraftment with full donor-type chimerism. At 10 years, the overall cumulative incidence of transplant-related mortality was 11% (SE, ±0.1%). It was 7% (SE, ±0.2%) after HTBI and 15% (SE, ±0.5%) after STBI (P=.3). The overall cumulative incidence of relapse was 33% (SE, ±0.5). It was 13% (SE, ±0.5%) after HTBI and 46% (SE, ±1%) after STBI (P=.02). The overall probability of disease-free survival (DFS) was 59% (SE, ±7%). It was 67% (SE, ±0.84%) after HTBI and 37% (SE, ±1.4%) after STBI (P=.01). Multivariate analyses showed the TBI schedule was the only risk factor that significantly affected relapse and DFS (P=.01 and P=.03, respectively)., Conclusions: In patients with acute leukemia, HTBI is more efficacious than STBI in eradicating minimal residual disease after HLA-matched T cell-depleted hematopoietic stem cell transplantation, thus affecting DFS., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Because activating killer cell immunoglobulinlike receptors (KIRs) are heterogeneously expressed in the population, we investigated the role of donor activating KIRs in haploidentical hematopoietic transplants for acute leukemia. Transplants were grouped according to presence vs absence of KIR-ligand mismatches in the graft-vs-host direction (ie, of donor-vs-recipient natural killer [NK]-cell alloreactivity). In the absence of donor-vs-recipient NK-cell alloreactivity, donor activating KIRs had no effects on outcomes. In the 69 transplant pairs with donor-vs-recipient NK-cell alloreactivity, transplantation from donors with KIR2DS1 and/or KIR3DS1 was associated with reduced risk of nonrelapse mortality, largely infection related (KIR2DS1 present vs absent: hazard ratio [HR], 0.25; P = .01; KIR3DS1 present vs absent: HR, 0.18; P = .006), and better event-free survival (KIR2DS1 present vs absent: HR, 0.31; P = .011; KIR3DS1 present vs absent: HR, 0.30; P = .008). Transplantation from donors with KIR2DS1 and/or KIR3DS1 was also associated with a 50% reduction in infection rate (P = .003). In vitro analyses showed that KIR2DS1 binding to its HLA-C2 ligand upregulated inflammatory cytokine production by alloreactive NK cells in response to infectious challenges. Because ∼40% of donors able to exert donor-vs-recipient NK-cell alloreactivity carry KIR2DS1 and/or KIR3DS1, searching for them may become a feasible, additional criterion in donor selection., (© 2015 by The American Society of Hematology.)

Today human leukocyte antigen-haploidentical transplantation is a feasible option for patients with high-risk acute leukemia who do not have matched donors. Whether it is T-cell replete or T-cell depleted, it is still, however, associated with issues of transplant-related mortality and posttransplant leukemia relapse. After reports that adoptive immunotherapy with T-regulatory cells controls the alloreactivity of conventional T lymphocytes in animal models, tomorrow's world of haploidentical transplantation will focus on new "designed" grafts. They will contain an appropriate ratio of conventional T lymphocytes and T-regulatory cells, natural killer cells, γ δ T cells, and other accessory cells. Preliminary results of ongoing clinical trials show the approach is feasible. It is associated with better immune reconstitution and a quite powerful graft-versus-leukemia effect with a low incidence of graft-versus-host disease and no need for posttransplant pharmacological prophylaxis. Future strategies will focus on enhancing the clinical benefit of T-regulatory cells by increasing their number and strengthening their function.

Background: Autologous stem cell transplantation (ASCT) generally provides good results in Hodgkin's lymphoma (HL). We studied a high-dose chemotherapy regimen based on thiotepa, etoposide and carboplatin (TECA)., Methods: Fifty-eight patients with advanced HL were treated with thiotepa, etoposide and carboplatin for transplant induction., Results: The overall response rate was 79·3% (39 CR: 67·2%; and 7 PR: 12·1%); 12 patients (20·1%) were non-responders. The 5-year overall survival rate was 77·6%; five initially responder patients relapsed within the first 5 years of follow-up and underwent salvage therapy., Conclusion: The TECA conditioning regimen for ASCT in HL results in a good anti-HL effect, positive response to treatment and high 5-year overall survival rate. It was also well tolerated and did not induce excessive toxicity, suggesting that TECA may be a very useful conditioning regimen for HL.

Hastening posttransplantation immune reconstitution is a key challenge in human leukocyte antigen (HLA)-haploidentical hematopoietic stem-cell transplantation (HSCT). In experimental models of mismatched HSCT, T-regulatory cells (Tregs) when co-infused with conventional T cells (Tcons) favored posttransplantation immune reconstitution and prevented lethal graft-versus-host disease (GVHD). In the present study, we evaluated the impact of early infusion of Tregs, followed by Tcons, on GVHD prevention and immunologic reconstitution in 28 patients with high-risk hematologic malignancies who underwent HLA-haploidentical HSCT. We show for the first time in humans that adoptive transfer of Tregs prevented GVHD in the absence of any posttransplantation immunosuppression, promoted lymphoid reconstitution, improved immunity to opportunistic pathogens, and did not weaken the graft-versus-leukemia effect. This study provides evidence that Tregs are a conserved mechanism in humans.

The C-type lectin receptor Dectin-1 plays a pivotal role in antifungal immunity. In this study, the recently characterized human DECTIN1 Y238X early stop codon polymorphism leading to diminished Dectin-1 receptor activity was studied in relation to invasive aspergillosis susceptibility and severity in patients receiving hematopoietic stem cell transplantation. We found that the presence of the DECTIN1 Y238X polymorphism in either donors or recipients of hematopoietic stem cell transplantation increased susceptibility to aspergillosis, with the risk being highest when the polymorphism was present simultaneously in both donors and recipients (adjusted hazard ratio = 3.9; P = .005). Functionally, the Y238X polymorphism impaired the production of interferon-γ and interleukin-10 (IL-10), in addition to IL-1β, IL-6, and IL-17A, by human peripheral mononuclear cells and Dectin-1 on human epithelial cells contributed to fungal recognition. Mechanistically, studies on preclinical models of infection in intact or bone marrow-transplanted Dectin-1 knockout mice revealed that protection from infection requires a distinct, yet complementary, role of both donor and recipient Dectin-1. This study discloses Dectin-1 deficiency as a novel susceptibility factor for aspergillosis in high-risk patients and identifies a previously unsuspected role for Dectin-1 in antifungal immunity that is the ability to control both resistance and tolerance to the fungus contingent on hematopoietic/nonhematopoietic compartmentalization.

Much progress has been made in the clinical, biological and technical aspects of the T-cell-depleted full-haplotype mismatched transplants for acute leukemia. Our experience demonstrates that infusing a megadose of extensively T-cell-depleted hematopoietic peripheral blood stem cells after an immuno-myeloablative conditioning regimen in acute leukemia patients ensures sustained engraftment with minimal graft-vs-host disease (GvHD) without the need of any post-transplant immunosuppressive treatment. Since our first successful pilot study, our efforts have concentrated on developing new conditioning regimens, optimizing the graft processing and improving the post-transplant immunological recovery. The results we have so far achieved in more than 200 high-risk acute leukemia patients show that haploidentical transplantation is now a clinical reality. Because virtually all patients in need of a hematopoietic stem cell transplant have a full-haplotype mismatched donor, who is immediately available, a T-cell depleted mismatched transplant should be offered, not as a last resort, but as a viable option to high risk acute leukemia patients who do not have, or cannot find, a matched donor.

Purpose: Establishment of hematopoietic stem-cell (HSC) transplantation from mismatched relatives is feasible for patients with acute leukemia. As our original method of graft processing was unsuitable for large-scale clinical studies, we use automated devices for CD34+ cell purification., Patients and Methods: Sixty-seven patients with acute myeloid leukemia (AML; 19 complete remission [CR] 1, 14 CR 2, nine CR > 2, 25 in relapse) and 37 with acute lymphoid leukemia (ALL; 14 CR 1, eight CR 2, two CR > 2, 13 in relapse) were conditioned with total-body irradiation, thiotepa, fludarabine, and antithymocyte globulin. Peripheral-blood progenitor cells were mobilized with recombinant human granulocyte colony-stimulating factor and depleted of T-cells using CD34+ cell immunoselection. No post-transplantation graft-versus-host disease (GvHD) prophylaxis was administered., Results: Primary engraftment was achieved in 94 of 101 assessable patients. Six of the seven patients who rejected the primary graft, engrafted after a second transplantation. Overall, 100 of 101 patients engrafted. Acute GvHD developed in eight of 100 patients, and chronic GvHD, in five of 70 assessable patients. Thirty-eight patients died of nonleukemic causes. Relapse occurred in nine of 66 patients receiving transplantation in remission and in 17 of 38 receiving transplantation in relapse. Median follow-up of the 40 patients who survived event-free was 22 months (range, 1 to 65 months). Event-free survival (+/- standard deviation) rate was 48% +/- 8% and 46% +/- 10%, respectively, for the 42 AML and 24 ALL patients receiving transplantation in remission., Conclusion: Our transplantation procedure provides reliable, reproducible CD34+ cell purification, high engraftment rates, and prevention of GvHD. The mismatched-related transplant emerges as a viable, alternative source of stem cells for acute leukemia patients without matched donors and/or those who urgently need transplantation.

Haploidentical stem cell transplantation has became a clinical reality in the last 10 years as it provides the chance of transplant for about 50% of patients with hematological malignancies who do not have a matched related or unrelated donor. Proper graft preparation for this type of transplant is crucial and this paper analyses our work over the past decade in the search for the optimal graft processing procedure moving from E-rosetting and soybean agglutination, through a combination of negative or positive selection of hematopoietic stem cells to the current method of one-step positive selection. In preparing a graft for haploidentical transplant, three essential requisites must be met. It must contain (1) a megadose (>10 x 10(6) x kg recipient b.w.) of hematopoietic stem cells to overcome the HLA histocompatibility barrier; (2) very few T-lymphocytes (CD3+ cells < 3 x 10(4)/kg recipient b.w.) to prevent severe acute and chronic graft-versus-host disease (GvHD); (3) very few B-lymphocytes to prevent Epstein-Barr virus-related lymphoproliferative disorders. With current graft processing technologies based on positive selection of hematopoietic stem cells, these requirements can be met. A 70-80% hematopoietic stem cell recovery ensures the target megadose is achieved in over 70% of cases with a T-cell depletion of more than 4 logs and a B-cell depletion of over 3 logs. Progress in graft processing has ensured primary, sustained engraftment rates of over 90% and has significantly reduced the incidence of severe acute GvHD and EBV-related lymphoproliferative disorders. Modern time-saving automated graft processing devices ensure reproducibility, reliability, and biological safety, which make widespread application of the haploidentical transplant currently feasible.

Abstract: We selected T regulatory cells (Tregs) from standard leukapheresis using double-negative selection (anti-CD8 and anti-CD19) followed by positive selection (anti-CD25) and 72 procedures were performed. A median of 263×106 cells (range 143–470×106) were recovered with a mean of CD4+/CD25+ cells of 94.5±2.4% (36.5±18.6% CD4+/CD25+hi). FoxP3+ cells were equal to 79.8%±22.2. CD127+ cells were 12.5%±8.2. The inhibition assay showed an inhibition rate of 67±22. Cells isolated by means of this approach can be used in allogeneic hematopoietic stem cell transplantation to reduce the incidence and severity of GvHD without bystander inhibition of general immunity. [Copyright &y& Elsevier]

Allogeneic hematopoietic stem cell transplantation (HSCT) is the most powerful therapy for patients with high risk of relapse. In spite of that, no matter the donor source or conditioning regimen used, leukemia relapse is still the leading cause of HSCT failure. In HLA-haploidentical HSCT, we recently applied a clinical protocol consisting of total body irradiation (TBI)-based conditioning regimen and a peripheral blood CD34+ cell graft combined with the adoptive transfer of naturally occurring regulatory T cells (Tregs) and conventional T cells (Tcons). No post-transplant pharmacologic GvHD prophylaxis was given. Such protocol was associated with low GvHD and relapse rate (Martelli et al., Blood 2014). To further reduce leukemia relapse in Treg/Tcon-based haploidentical HSCT (Treg/Tcon haplo-HSCT) we used high dose hyper-fractionated TBI (HF-TBI) in the conditioning regimen. We also extended Treg/Tcon haplo-HSCT to patients that are unfit (because of previous comorbidities) and/or too old to withstand high intensity regimens. In these patients the extra-hematologic toxicity of irradiation was reduced with the use of targeted total marrow and lymph node irradiation (TMLI). 40 patients with high risk acute leukemia (36 AML, 4 ALL) received Treg/Tcon haplo-HSCT. All but 3 patients were transplanted in complete remission. 12 younger patients (median age: 28, range: 20-43) received HF-TBI, while 28 older or unfit patients (59, 40-70) received TMLI in the conditioning regimen. HF-TBI (14.4 Gy) was administered in 12 fractions, 3 times a day for 4 days. TMLI was administered by means of Helical Tomotherapy HI-ART (9 fractions, 2 times a day for 4.5 days). Irradiation was followed by chemotherapy with Thiotepa, Fludarabine, and Cyclophosphamide. 2 × 106/kg freshly isolated CD4+CD25+FOXP3+ Tregs were transferred 4 days before the infusion of 1 × 106/kg Tcons and a mega-dose of CD34+ hematopoietic stem cells. No post-transplant pharmacologic GvHD prophylaxis was given. 38/40 patients engrafted. 12 (31%) developed aGvHD grade ³2 (10 are alive and off-therapy). 6 (16%) died because of transplant related complications (2 because of aGvHD, 2 infections, 1 veno-occlusive disease, 1 intracranial hemorrhage). Strikingly, despite the high risk diseases, no patient relapsed after a median follow up of 13 months (range 1-36, Fig. A). Further, only 1 patient developed cGvHD. Thus, cGvHD/Leukemia-free survival was 82% (Fig. B). Treg adoptive transfer allows for the safe infusion of an otherwise lethal dose of donor alloreactive Tcons in the absence of any other form of immune suppression. Our results demonstrate that the potent graft versus leukemia effect of Treg/Tcon adoptive transfer was boosted by high dose marrow irradiation. Thus, this study proves that the right combination of haploidentical Treg/Tcon immunotherapy plus a powerful conditioning regimen can fully eradicate leukemia. [ABSTRACT FROM AUTHOR]