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The most frequent subtype of acute myeloid leukemia (AML) is defined by mutations in the nucleophosmin 1 (NPM1) gene. Mutated NPM1 (ΔNPM1) is an attractive target for immunotherapy, since it is an essential driver gene and 4 bp frameshift insertions occur in the same hotspot in 30%-35% of AMLs, resulting in a C-terminal alternative reading frame of 11 aa. By searching the HLA class I ligandome of primary AMLs, we identified multiple ΔNPM1-derived peptides. For one of these peptides, HLA-A*02:01-binding CLAVEEVSL, we searched for specific T cells in healthy individuals using peptide-HLA tetramers. Tetramer-positive CD8+ T cells were isolated and analyzed for reactivity against primary AMLs. From one clone with superior antitumor reactivity, we isolated the T cell receptor (TCR) and demonstrated specific recognition and lysis of HLA-A*02:01-positive ΔNPM1 AML after retroviral transfer to CD8+ and CD4+ T cells. Antitumor efficacy of TCR-transduced T cells was confirmed in immunodeficient mice engrafted with a human AML cell line expressing ΔNPM1. In conclusion, the data show that ΔNPM1-derived peptides are presented on AML and that CLAVEEVSL is a neoantigen that can be efficiently targeted on AML by ΔNPM1 TCR gene transfer. Immunotherapy targeting ΔNPM1 may therefore contribute to treatment of AML. [ABSTRACT FROM AUTHOR]

Background: Myeloablative (MAC) and reduced-intensity conditioning (RIC) are established approaches for allogeneic stem cell transplantation (SCT) in acute myeloid leukemia (AML). Most deaths after MAC occur within the first 2 years after SCT, while patients surviving leukemia-free for 2 years can expect a favorable long-term outcome. However, there is paucity of data on the long-term outcome (beyond 10 years) and the pattern of late events following RIC due to the relative recent introduction of this approach. Methods: We analyzed long-term outcomes in a cohort of 1423 AML patients, age =50 years, after SCT from HLA-matched siblings, during the years 1997-2005, median follow-up 8.3 years (0.1-17). Results: The 10-year leukemia-free survival (LFS) was 31 % (95CI, 27-35) and 32 % (28-35) after MAC and RIC, respectively (P = 0.57). The 10-year GVHD/ relapse-free survival (GRFS), a surrogate for quality of life was 22 % (18-25) and 21 % (18-24), respectively (P = 0.79). The 10-year non-relapse mortality (NRM) was higher and relapse rate was lower after MAC, throughout the early and late post-transplant course. The 10-year LFS among 584 patients surviving leukemia-free 2 years after SCT was 71 % (65-76) and 73 % (67-78) after MAC and RIC, respectively (P = 0.76). Advanced leukemia at SCT was the major predictor of LFS subsequent to the 2-year landmark. Relapse was the major cause of late death after both regimens; however, NRM and in particular chronic graft-versus-host disease and second cancers were more common causes of late death after MAC. Conclusions: Long-term LFS and GRFS are similar after RIC and MAC. Most events after RIC or MAC occur within the first 2 years after SCT. Patients who are leukemia-free 2 years after SCT can expect similar good subsequent outcome after both approaches. [ABSTRACT FROM AUTHOR]

Thiotepa is an alkylating compound with an antineoplastic and myeloablative activity and can mimic the effect of radiation. However, it is unknown whether this new regimen could safely replace the longestablished ones. This retrospective matched-pair analysis evaluated the outcome of adults with acute myeloid leukaemia in first complete remission who received myeloablative conditioning either with a thiotepa-based (n = 121) or a cyclophosphamide/total body irradiation-based (TBI; n = 358) regimen for allogeneic hematopoietic stem cell transplantation from an HLA-matched sibling or an unrelated donor. With a median follow-up of 44 months, the outcome was similar in both groups. Acute graft-versus-host disease grade II-IV was observed in 25% after thiotepa-containing regimen versus 35% after TBI (P = 0.06). The 2-yr cumulative incidence of chronic graft-versus-host disease was 40.5% for thiotepa and 41% for TBI (P = 0.98). At 2 yrs, the cumulative incidences of non-relapse mortality and relapse incidence were 23.9% (thiotepa) vs. 22.4% (TBI; P = 0.66) and 17.2% (thiotepa) vs. 23.3% (TBI; P = 0.77), respectively. The probabilities of leukaemia-free and overall survival at 2 yrs were not significantly different between the thiotepa and TBI groups, at 58.9% vs. 54.2% (P = 0.95) and 61.4% vs. 58% (P = 0.72), respectively. Myeloablative regimens using combinations including thiotepa can provide satisfactory outcomes, but the optimal conditioning remains unclear for the individual patient in this setting. [ABSTRACT FROM AUTHOR]

Allogeneic hematopoietic cell transplantation is a potentially curative treatment in patients with acute myeloid leukemia. Recent advances in the field of hematopoietic cell allografting have resulted in a practice shift, favoring less intense preparative regimens. We present results of a retrospective comparative analysis of two preparative regimens, namely FB2 (IV fludarabine plus IV busulfan 6.4 mg/kg ± 10%) and FB4 (IV fludarabine plus IV busulfan 12.8 mg/kg ±10%), in patients with acute myeloid leukemia undergoing hematopoietic cell allografting in second complete remission at EBMT participating centers. Between 2003 and 2010, 128 AML patients in second complete remission were allografted following a preparative regimen of FB2 ( n = 88) or FB4 ( n = 40). The median time-to-neutrophil engraftment was similar whether patients received FB2 (16 (5–38) days) or FB4 (16 (9–29) days), p = 0.45. A multivariate analysis showed that use of FB4 resulted in improved 2-year leukemia-free (HR = 0.44 (95%CI = 0.21, 0.94), p = 0.03) and overall survival (HR = 0.38 (95%CI = 0.16, 0.86), p = 0.02). Cumulative incidence of non-relapse mortality (2-year) for all patients was 21% (95%CI = 14–28%). Our analysis suggests that FB4 improves 2-year leukemia-free and overall survival in AML allografted in second complete remission. A confirmatory randomized controlled trial that compares these two preparative regimens (FB2 vs. FB4) in AML in CR2 is definitely warranted. [ABSTRACT FROM AUTHOR]

Simple Summary: Acute myeloid leukemia (AML) is an aggressive hematological malignancy with poor prognosis. For AML relapses after chemotherapy, new and effective therapies are needed. In 30–35% of AMLs, a frameshift mutation in the nucleophosmin 1 gene (dNPM1) creates potential neoantigens that are attractive targets for immunotherapy. We previously isolated a T-cell receptor (TCR) that targets an HLA-A*02:01-binding dNPM1 neoantigen on primary AML. Here, we investigated whether AVEEVSLRK is another dNPM1 neoantigen that can be targeted by TCR gene transfer. We isolated various T-cells, cloned the HLA-A*11:01-restricted TCR from one T-cell clone and, upon transfer to CD8 cells, demonstrated targeting of dNPM1 primary AMLs in vitro. However, the TCR failed to mediate an anti-tumor effect in immunodeficient mice engrafted with dNPM1 OCI-AML3 cells. Our results demonstrate that AVEEVSLRK is an HLA-A*11:01-binding neoantigen on dNPM1 AML. Whether the isolated TCR is of sufficient affinity to treat patients remains uncertain. Acute myeloid leukemia (AML) is a hematological malignancy caused by clonal expansion of myeloid progenitor cells. Most patients with AML respond to chemotherapy, but relapses often occur and infer a very poor prognosis. Thirty to thirty-five percent of AMLs carry a four base pair insertion in the nucleophosmin 1 gene (NPM1) with a C-terminal alternative reading frame of 11 amino acids. We previously identified various neopeptides from the alternative reading frame of mutant NPM1 (dNPM1) on primary AML and isolated an HLA-A*02:01-restricted T-cell receptor (TCR) that enables human T-cells to kill AML cells upon retroviral gene transfer. Here, we isolated T-cells recognizing the dNPM1 peptide AVEEVSLRK presented in HLA-A*11:01. The TCR cloned from a T-cell clone recognizing HLA-A*11:01+ primary AML cells conferred in vitro recognition and lysis of AML upon transfer to CD8 cells, but failed to induce an anti-tumor effect in immunodeficient NSG mice engrafted with dNPM1 OCI-AML3 cells. In conclusion, our data show that AVEEVSLRK is a dNPM1 neoantigen on HLA-A*11:01+ primary AMLs. CD8 cells transduced with an HLA-A*11:01-restricted TCR for dNPM1 were reactive against AML in vitro. The absence of reactivity in a preclinical mouse model requires further preclinical testing to predict the potential efficacy of this TCR in clinical development. [ABSTRACT FROM AUTHOR]

Background: The therapeutic value of donor lymphocyte infusions in patients who relapse with acute myeloid leukemia (AML) after allogeneic hematopoietic stem cell transplantation (HSCT) is limited by a low efficacy and the risk of graft-versus-host disease. We aimed at generating leukemia-reactive donor T cells for patients with AML. Methods: Peripheral blood mononuclear cells of the donor were stimulated with mature donor dendritic cells, pulsed with irradiated patient leukemic blasts (LB), or directly with cytokine-treated LB. After 3 weekly stimulations, donor cells were tested for anti-leukemic reactivity in an IFNγ Elispot. Results: In 5 of 6 donors, cells with reactivity against patient LB with low or absent reactivity against non-leukemic cells could be generated. T cell subset analyses in 2 donors indicated that specific anti-leukemic reactivity was mainly mediated by CD4+ T cells, which were also the predominant cell fraction in 4 of 6 donors. One leukemia-reactive donor T cell line was expanded with a recently developed system. One week of expansion resulted in a 10-fold increase in reactivity with sustained specificity of the resulting T cell line. Conclusions: Our results show the feasibility of the in vitro generation of leukemia-reactive donor lymphocytes, rendering this method a promising tool for post-HSCT immunotherapy. Copyright © 2007 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]