Mild chronic graft-versus-host disease may alleviate poor prognosis associated with FLT3 internal tandem duplication for adult acute myeloid leukemia following allogeneic stem cell transplantation with myeloablative conditioning in first complete remission: a retrospective study

The FLT3-ITD allelic ratio and NPM1 mutation do not impact outcomes in AML patients with FLT3-ITD after allo-HSCT: a retrospective propensity-score matching study

BACKGROUND

FLT3-ITD mutation has consistently been correlated with poor outcomes in AML patients. Allo-HSCT (allogeneic hematopoietic stem cell transplantation) plays a major role in curing blood diseases. Whether allo-HSCT can eliminate the detrimental effects of FLT3-ITD mutation in AML patients remains debatable. In addition, studies showed that FLT3-ITD allelic ratio (AR) and NPM1 mutation appear to further influence the prognostic utility of FLT3-ITD in patients with FLT3-ITD-mutated AML. The influence of NPM1 mutation and AR on FLT3-ITDmut patients remains unclear in our database.

OBJECTIVE

To compare the survival outcomes following allo-HSCT between FLT3-ITDmut and FLT3-ITDwt patients and further analyze the influence of NPM1 and AR on outcomes.

STUDY DESIGN

118 FLT3-ITDmut patients and 497 FLT3-ITDwt patients with allo-HSCT were matched 1:3 on the propensity score using a nearest-neighbor matching with a caliper size of 0.2. 430 AML patients were considered, including 116 FLT3-ITDmut patients and 314 FLT3-ITDwt patients.

RESULTS

OS (overall survival) and LFS (leukemia-free survival) of FLT3-ITDmut patients were similar to FLT3-ITDwt (2-year OS:78.5% vs 82.6%, P=0.374; 2-year LFS: 75.1% vs 80.8%, P= 0.215). A cut-off of 0.50 was applied to define subgroups with a low or high AR of FLT3-ITD, no significant CIR (cumulative incidence of relapse) and LFS differences were observed between the low AR and high AR groups (2-year CIR: P=0.617; 2-year LFS: P=0.563). CIR and LFS were comparable when patients were grouped according to the presence or absence of NPM1 and FLT3-ITD (2-year CIR: P=0.356; 2-year LFS: P=0.159). Additionally, the CIR and LFS of FLT3-ITDmut and FLT3-ITDwt patients tended to be different after MSD-HSCT (matched-sibling donor hematopoietic stem cell transplantation) (2-year CIR: P= 0.072; 2-year LFS: P= 0.084), however, the differences were not observed in patients with haplo-HSCT (2-year CIR: P= 0.59; 2-year LFS: P= 0.794). The presence of MRD before transplantation and non-CR1 were risk factors related to inferior outcomes in a multivariate analysis, regardless of FLT3-ITD or NPM1 status.

CONCLUSION

Our results suggested that allo-HSCT, especially haplo-HSCT, may overcome the adverse effect of FLT3-ITD mutation, regardless of the NPM1 status or AR. Allo-HSCT could be an ideal option for AML patients with FLT3-ITD.

Targeting MDM2 enhances antileukemia immunity after allogeneic transplantation via MHC-II and TRAIL-R1/2 upregulation

Patients with acute myeloid leukemia (AML) often achieve remission after allogeneic hematopoietic cell transplantation (allo-HCT) but subsequently die of relapse driven by leukemia cells resistant to elimination by allogeneic T cells based on decreased major histocompatibility complex II (MHC-II) expression and apoptosis resistance. Here we demonstrate that mouse-double-minute-2 (MDM2) inhibition can counteract immune evasion of AML. MDM2 inhibition induced MHC class I and II expression in murine and human AML cells. Using xenografts of human AML and syngeneic mouse models of leukemia, we show that MDM2 inhibition enhanced cytotoxicity against leukemia cells and improved survival. MDM2 inhibition also led to increases in tumor necrosis factor-related apoptosis-inducing ligand receptor-1 and -2 (TRAIL-R1/2) on leukemia cells and higher frequencies of CD8+CD27lowPD-1lowTIM-3low T cells, with features of cytotoxicity (perforin+CD107a+TRAIL+) and longevity (bcl-2+IL-7R+). CD8+ T cells isolated from leukemia-bearing MDM2 inhibitor-treated allo-HCT recipients exhibited higher glycolytic activity and enrichment for nucleotides and their precursors compared with vehicle control subjects. T cells isolated from MDM2 inhibitor-treated AML-bearing mice eradicated leukemia in secondary AML-bearing recipients. Mechanistically, the MDM2 inhibitor-mediated effects were p53-dependent because p53 knockdown abolished TRAIL-R1/2 and MHC-II upregulation, whereas p53 binding to TRAILR1/2 promotors increased upon MDM2 inhibition. The observations in the mouse models were complemented by data from human individuals. Patient-derived AML cells exhibited increased TRAIL-R1/2 and MHC-II expression on MDM2 inhibition. In summary, we identified a targetable vulnerability of AML cells to allogeneic T-cell-mediated cytotoxicity through the restoration of p53-dependent TRAIL-R1/2 and MHC-II production via MDM2 inhibition.

Durable remission of post-transplant relapsed FLT3-ITD AML in response to gilteritinib administration after a second transplant from the same donor

Patients with FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) acute myeloid leukemia (AML) respond to conventional induction chemotherapy, with remission rates similar to those seen in other subtypes; however, they are much more likely to relapse and relapse is rapid. For this reason, eligible patients receive consolidation therapy with early allogenic transplantation, but the recurrence rate remains high, even after transplantation. Moreover, the optimal therapy for patients with FLT3-ITD AML who relapse after allogeneic hematopoietic stem cell transplantation remains unclear. Here, we report a case in which graft-versus-leukemia (GVL) effects were induced by gilteritinib administration after a second transplant from the same donor, resulting in sustained remission of early FLT3-ITD AML relapse after allogeneic transplantation. Several studies suggest that the benefits of FLT3 tyrosine kinase inhibitors (FLT3-TKI) after allogeneic transplantation are attributable to GVL induction, as well as direct effects on FLT3 mutation-positive leukemia cells. With this in mind, we induced lymphodepletion using L-PAM to further enhance GVL induction by donor lymphocytes and FLT3-TKI. We believe that enhancement of GVL induction by lymphodepletion should be considered before FLT3-TKI use, if the prognosis is very poor, such as in patients with recurrence following allogeneic transplantation.

Allogeneic Stem Cell Transplantation in Patients With FLT3-ITD Mutated AML: Transplantation in CR1 Is the Decisive Factor for Good Outcome

BACKGROUND

Patients with internal tandem duplication in fms-related tyrosine kinase receptor gene 3 (FLT3-ITD)-mutated acute myeloid leukemia (AML) have a dismal prognosis and the only curative option seems to be allogeneic stem cell transplantation (alloSCT). However, its timing is still matter of debate.

PATIENTS AND METHODS

We retrospectively analyzed 73 consecutive AML patients with FLT3-ITD (median age 53, range 20-68 years) allografted with consistent policy to try to refer them all for upfront alloSCT in first complete remission (CR1).

RESULTS

With a median follow-up of 44 (range, 5-135) months the 5-year overall survival (OS)/disease-free survival (DFS) probabilities were 49%/47%. The cumulative incidence of relapse and nonrelapse mortality (NRM) were 37% and 14%, respectively. The estimated 5-year OS for patients who received transplantation in CR1 was 62% versus 0% for patients who received transplantation beyond CR1. Multivariable analysis identified stem cell transplantation beyond CR1 as the key factor for poor OS (hazard ratio [HR], 5.41; P < .0001), DFS (HR, 4.41; P = .0002), and high relapse incidence (HR, 8.08; P < .0001). Acute graft versus host disease Grade ≥3 predicted higher NRM (HR, 3.80; P = .059) as well as inferior OS (HR, 2.04; P = .0079). No association of patient age, nucleophosmin status, donor type, conditioning, and other variables on the survival was detected.

CONCLUSION

AlloSCT should be regarded with urgency as soon as CR1 is achieved in this subset of AML patients.

Incubation of Immune Cell Grafts With MAX.16H5 IgG1 Anti-Human CD4 Antibody Prolonged Survival After Hematopoietic Stem Cell Transplantation in a Mouse Model for Fms Like Tyrosine Kinase 3 Positive Acute Myeloid Leukemia

Despite the constant development of innovative therapeutic options for hematological malignancies, the gold-standard therapy regimen for curative treatment often includes allogeneic hematopoietic stem cell transplantation (HSCT). The graft-vs.-leukemia effect (GVL) is one of the main therapeutic goals that arises from HSCT. On the other hand, graft-vs.-host disease (GVHD) is still one of the main and most serious complications following allogeneic HSCT. In acute myeloid leukemia (AML), HSCT together with high-dose chemotherapy is used as a treatment option. An aggressive progression of the disease, a decreased response to treatment, and a poor prognosis are connected to internal tandem duplication (ITD) mutations in the Fms like tyrosine kinase 3 (FLT3) gene, which affects around 30% of AML patients. In this study, C3H/HeN mice received an allogeneic graft together with 32D-FLT3^ITD AML cells to induce acute GVHD and GVL. It was examined if pre-incubation of the graft with the anti-human cluster of differentiation (CD) 4 antibody MAX.16H5 IgG₁ prevented the development of GVHD and whether the graft function was impaired. Animals receiving grafts pre-incubated with the antibody together with FLT3^ITD AML cells survived significantly longer than mice receiving untreated grafts. The observed prolonged survival due to MAX.16H5 incubation of immune cell grafts prior to transplantation may allow an extended application of additional targeted strategies in the treatment of AML.

Sorafenib promotes graft-versus-leukemia activity in mice and humans through IL-15 production in FLT3-ITD-mutant leukemia cells

Individuals with acute myeloid leukemia (AML) harboring an internal tandem duplication (ITD) in the gene encoding Fms-related tyrosine kinase 3 (FLT3) who relapse after allogeneic hematopoietic cell transplantation (allo-HCT) have a 1-year survival rate below 20%. We observed that sorafenib, a multitargeted tyrosine kinase inhibitor, increased IL-15 production by FLT3-ITD+ leukemia cells. This synergized with the allogeneic CD8+ T cell response, leading to long-term survival in six mouse models of FLT3-ITD+ AML. Sorafenib-related IL-15 production caused an increase in CD8+CD107a+IFN-γ+ T cells with features of longevity (high levels of Bcl-2 and reduced PD-1 levels), which eradicated leukemia in secondary recipients. Mechanistically, sorafenib reduced expression of the transcription factor ATF4, thereby blocking negative regulation of interferon regulatory factor 7 (IRF7) activation, which enhanced IL-15 transcription. Both IRF7 knockdown and ATF4 overexpression in leukemia cells antagonized sorafenib-induced IL-15 production in vitro. Human FLT3-ITD+ AML cells obtained from sorafenib responders following sorafenib therapy showed increased levels of IL-15, phosphorylated IRF7, and a transcriptionally active IRF7 chromatin state. The mitochondrial spare respiratory capacity and glycolytic capacity of CD8+ T cells increased upon sorafenib treatment in sorafenib responders but not in nonresponders. Our findings indicate that the synergism of T cells and sorafenib is mediated via reduced ATF4 expression, causing activation of the IRF7-IL-15 axis in leukemia cells and thereby leading to metabolic reprogramming of leukemia-reactive T cells in humans. Therefore, sorafenib treatment has the potential to contribute to an immune-mediated cure of FLT3-ITD-mutant AML relapse, an otherwise fatal complication after allo-HCT.

Predictive significance of the European LeukemiaNet classification of genetic aberrations in patients with acute myeloid leukaemia undergoing allogeneic stem cell transplantation

OBJECTIVES

The purpose of this study was to evaluate the predictive capacity of the European LeukemiaNet (ELN) classification of genetic risk in patients with acute myeloid leukaemia (AML) undergoing allogeneic stem cell transplantation (alloSCT).

METHODS

We retrospectively analysed 274 patients transplanted at our centre between 2004 and 2014.

RESULTS

The ELN grouping is comparable to the Southwest Oncology Group/Eastern Cooperative Oncology Group (SWOG/ECOG) stratification in predicting the outcome after alloSCT [overall P = 0.0064 for disease-free survival (DFS), overall P = 0.003 for relapse]. Patients with an intermediate-1 profile have a significantly elevated 5-yr relapse incidence as compared to favourable risk patients, that is 40% vs. 15%, [hazard ratio (HR) 2.58, P = 0.048]. An intermediate-1 risk profile is an independent predictor for relapse as determined by multivariate Cox regression analysis (HR 3.05, P = 0.023). In intermediate-1 patients, the presence of an FLT3 internal tandem duplication (FLT3-ITD) is associated with a significantly increased relapse incidence (P = 0.0323), and a lower DFS (P = 0.0465). FLT3-ITD is an independent predictor for overall survival, DFS and relapse incidence in the intermediate-1 subgroup.

CONCLUSIONS

The ELN stratification of genetic risk predicts the outcome of patients with AML undergoing alloSCT. Patients with an intermediate-1 profile have a high risk for treatment failure due to relapse, which prompts the development of alternative treatment strategies.