Haematopoietic cell transplantation with and without sorafenib maintenance for patients with FLT3-ITD acute myeloid leukaemia in first complete remission

Strategies for Enhancing and Preserving Anti-leukemia Effects Without Aggravating Graft-Versus-Host Disease

Allogeneic stem cell transplantation (allo-SCT) is a curable method for the treatment of hematological malignancies. In the past two decades, the establishment of haploidentical transplant modalities make “everyone has a donor” become a reality. However, graft-versus-host disease (GVHD) and relapse remain the major two causes of death either in the human leukocyte antigen (HLA)-matched transplant or haploidentical transplant settings, both of which restrict the improvement of transplant outcomes. Preclinical mice model showed that both donor-derived T cells and natural killer (NK) cells play important role in the pathogenesis of GVHD and the effects of graft-versus-leukemia (GVL). Hence, understanding the immune mechanisms of GVHD and GVL would provide potential strategies for the control of leukemia relapse without aggravating GVHD. The purpose of the current review is to summarize the biology of GVHD and GVL responses in preclinical models and to discuss potential novel therapeutic strategies to reduce the relapse rate after allo-SCT. We will also review the approaches, including optimal donor selection and, conditioning regimens, donor lymphocyte infusion, BCR/ABL-specific CTL, and chimeric antigen receptor-modified T cells, which have been successfully used in the clinic to enhance and preserve anti-leukemia activity, especially GVL effects, without aggravating GVHD or alleviate GVHD.

FLT3 inhibitors in acute myeloid leukemia

FLT3 mutations are one of the most common findings in acute myeloid leukemia (AML). FLT3 inhibitors have been in active clinical development. Midostaurin as the first-in-class FLT3 inhibitor has been approved for treatment of patients with FLT3-mutated AML. In this review, we summarized the preclinical and clinical studies on new FLT3 inhibitors, including sorafenib, lestaurtinib, sunitinib, tandutinib, quizartinib, midostaurin, gilteritinib, crenolanib, cabozantinib, Sel24-B489, G-749, AMG 925, TTT-3002, and FF-10101. New generation FLT3 inhibitors and combination therapies may overcome resistance to first-generation agents.

The Dilemma of Conditioning Intensity: When Does Myeloablative Conditioning Improve Outcomes for Allogeneic Hematopoietic Cell Transplantation

The impact of conditioning intensity on different disease risk index (DRI) groups has not been evaluated. We retrospectively analyzed acute myelogenous leukemia (AML)/myelodysplastic syndrome (MDS) hematopoietic cell transplantation (HCT) recipients in 2 groups based on DRI, to assess the impact of conditioning intensity on overall survival (OS), disease free survival (DFS), relapse, and nonrelapse mortality (NRM). A total of 380 patients with either high/very high (n = 148) or low/intermediate DRI (n = 232) myeloid malignancy (AML, n = 278; MDS, n = 102) were included in the analysis. Median follow-up for survivors was 35 months. Median age was 58years (range, 18 to 75). Patient and transplant-related characteristics were 41% reduced-intensity conditioning (RIC), 59% myeloablative conditioning (MAC), 13% bone marrow graft, 29% matched related donor, 49% matched unrelated donor, 22% haploidentical donor, and 52% HCT-specific comorbidity index ≥ 3. Among patients with high/very high DRI, there was no difference in OS, DFS, relapse, and NRM between RIC and MAC conditioning groups. For low/intermediate risk DRI recipients of MAC had better 3-year OS estimate (69% versus 57%, P = .001), DFS (65% versus 51%, P = .003), and lower relapse (3-year cumulative incidence, 17% versus 32%; P = .01) but similar NRM (19% versus 17%, P = .04) to RIC recipients. On multivariable analysis MAC was associated with better DFS (hazard ratio [HR], .58; 95% confidence interval [CI], .39-.88; P = .01), lower relapse (HR, .56; 95% CI, .32 to .97; P = .038), and similar NRM (HR, 1.11; 95% CI, .54 to 2.26; P = .781) compared with RIC in the low/intermediate DRI group. Intensity had no impact on HCT outcomes in the high/very high DRI group. MAC improves DFS and relapse compared with RIC among AML/MDS patients with low/intermediate DRI. The finding of no such benefit in high/very high DRI needs to be further explored in a larger cohort with a longer follow-up.

Measurable residual disease, conditioning regimen intensity, and age predict outcome of allogeneic hematopoietic cell transplantation for acute myeloid leukemia in first remission: A registry analysis of 2292 patients by the Acute Leukemia Working Party European Society of Blood and Marrow Transplantation

Patients with acute myeloid leukemia (AML) in morphological first complete remission (CR1) pre-allogeneic hematopoietic cell transplantation (HCT) may have measurable residual disease (MRD) by molecular and immunophenotyping criteria. We assessed interactions of MRD status with HCT conditioning regimen intensity in patients aged <50 years (y) or ≥50y. This was a retrospective study by the European Society for Blood and Marrow Transplantation registry. Patients were >18y with AML CR1 MRD NEG/POS and recipients of HCT in 2000-2015. Conditioning regimens were myeloablative (MAC), reduced intensity (RIC) or non-myeloablative (NMA). Outcomes included leukemia free survival (LFS), overall survival (OS), relapse incidence (RI), non-relapse mortality (NRM), chronic graft-vs-host (cGVHD), and GVHD-free and relapse-free survival (GRFS). The 2292 eligible patients were categorized into four paired groups: <50y MRD POS MAC (N = 240) vs RIC/NMA (N = 58); <50y MRD NEG MAC (N = 665) vs RIC/NMA (N = 195); ≥50y MRD POS MAC (N = 126) vs RIC/NMA (N = 230), and ≥50y MRD NEG MAC (N = 223) vs RIC/NMA (N = 555). In multivariate analysis RIC/NMA was only inferior to MAC for patients in the <50y MRD POS group, with worse RI (HR 1.71) and LFS (HR 1.554). Patients <50Y MRD NEG had less cGVHD after RIC/NMA HCT (HR 0.714). GRFS was not significantly affected by conditioning intensity in any group. Patients aged <50y with AML CR1 MRD POS status should preferentially be offered MAC allo-HCT. Prospective studies are needed to address whether patients with AML CR1 MRD NEG may be spared the toxicity of MAC regimens. New approaches are needed for ≥50y AML CR1 MRD POS.

New approaches in allogenic transplantation in AML

Acute myeloid leukemia (AML) is a heterogeneous disorder with high morbidity and mortality. Allogeneic stem cell transplantation (allo-SCT) is an effective, and sometimes the only, curative postremission therapy for AML patients. Based on genetic risk classification, the published data have suggested that allo-SCT be recommended for high- and most intermediate-risk AML but not for low-risk AML in first complete remission (CR1). Recently, the role of allo-SCT in low-risk AML in CR1 is being established with the development of a risk-directed, minimal residual disease-based strategy. Though human leukocyte antigen-matched sibling transplantation remains the preferred therapeutic option for AML, modern approaches and developments pre-, peri- and post-transplant have facilitated other transplant modalities, especially haploidentical SCT, as promising valid alternative choices. In this paper, we review recent advances in allo-SCT for AML, weigh the benefits of allo-SCT for high-, intermediate-, and even low-risk AML in CR1, discuss the best choice of allo-SCT donor for the treatment of AML, and summarize new approaches for refractory and relapsed AML pre- or post-allo-SCT.

Post-remission strategies for the prevention of relapse following allogeneic hematopoietic cell transplantation for high-risk acute myeloid leukemia: expert review from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Acute myeloid leukemia (AML) is an aggressive hematopoietic malignancy generally associated with poor prognosis. Allogeneic hematopoietic cell transplantation (alloHCT) continues to be the most potent anti-leukemia treatment for adult patients with intermediate and high-risk AML. However, disease relapse after alloHCT remains unacceptably high and is the primary cause of treatment failure and mortality following alloHCT. It is therefore that post-transplant early cellular or pharmacologic maintenance or preemptive strategies to enhance the graft-versus-leukemia effect or to eradicate persistent minimal residual disease have been of renewed interest, particularly with the availability of more sensitive technologies to measure residual AML. Although preliminary studies have demonstrated improved outcomes with the use of post-alloHCT remission therapies, prospective randomized trials are required to determine their clinical efficacy and role in the treatment of AML. On behalf of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation, we summarize the available evidence on the use and efficacy of available pharmacologic post-remission therapies, including hypomethylating agents, deacetylase inhibitors, and tyrosine kinase inhibitors, as well as cellular therapies, including preemptive and prophylactic donor lymphocyte infusions for the prevention of relapse of AML.

Recent advances in the understanding and treatment of acute myeloid leukemia

Acute myeloid leukemia (AML) is a clinically and genetically heterogeneous disease that has a poor prognosis. Recent advances in genomics and molecular biology have led to a greatly improved understanding of the disease. Until 2017, there had been no new drugs approved for AML in decades. Here, we review novel drug targets in AML with a focus on epigenetic-targeted therapies in pre-clinical and clinical development as well as the recent new drug approvals.

Reduced-Intensity Conditioning Followed by Related and Unrelated Allografts for Hematologic Malignancies: Expanded Analysis and Long-Term Follow-Up

Reduced-intensity conditioning (RIC) extends the curative potential of allogeneic hematopoietic cell transplantation (HCT) to patients with hematologic malignancies unable to withstand myeloablative conditioning. We prospectively analyzed the outcomes of 292 consecutive patients, median age 58 years (range, 19 to 75) with hematologic malignancies treated with a uniform RIC regimen of cyclophosphamide, fludarabine, and total body irradiation (200 cGy) with or without antithymocyte globulin and cyclosporine and mycophenolate mofetil graft-versus-host disease (GVHD) prophylaxis followed by allogeneic HCT at the University of Minnesota from 2002 to 6. Probability of 5-year overall survival was 78% for patients with indolent non-Hodgkin lymphoma, 53% for chronic myelogenous leukemia, 55% for Hodgkin lymphoma, 40% for acute myelogenous leukemia, 37% for myelodysplastic syndrome, 29% for myeloma, and 14% for myeloproliferative neoplasms. Corresponding outcomes for relapse were 0%, 13%, 53%, 37%, 39%, 75%, and 29%, respectively. Disease risk index (DRI) predicted both survival and relapse with superior survival (64%) and lowest relapse (16%) in those with low risk score compared with 24% survival and 57% relapse in those with high/very-high risk scores. Recipient cytomegalovirus (CMV)-positive serostatus was protective from relapse with the lowest rates in those also receiving a CMV-positive donor graft (29%). The cumulative incidence of 2-year nonrelapse mortality was 26% and was lowest in those receiving a matched sibling graft at 21%, with low (21%) or intermediate (18%) HCT-specific comorbidity index, and was similar across age groups. The incidence of grades II to IV acute GVHD was 43% and grades III to IV 27%; the highest rates were found in those receiving an unrelated donor (URD) peripheral blood stem cell (PBSC) graft, at 50%. Chronic GVHD at 1 year was 36%. Future approaches incorporating alternative GVHD prophylaxis, particularly for URD PBSC grafts, and targeted post-transplant antineoplastic therapies for those with high DRI are indicated to improve these outcomes.

The role of FLT3 inhibitors as maintenance therapy following hematopoietic stem cell transplant

Activating mutations in FLT3 in acute myeloid leukemia (AML) portend a poor prognosis, and targeting FLT3 with a tyrosine kinase inhibitor has been an area of intense research recently. Most FLT3 mutated AML patients undergo hematopoietic stem cell transplantation (HSCT) as standard of care but a significant proportion of patients relapse. Although the use of FLT3 inhibitors in the pre-HSCT perspective is more clearly defined, its use in the post-HSCT scenario, when most relapses occur, remains unclear. In this review, we comprehensively present the data on the recent and ongoing studies evaluating the role of various FLT3 inhibitors in AML with a particular focus in the post-HSCT setting.

Optimizing the pretransplant regimen for autologous stem cell transplantation in acute myelogenous leukemia: Better outcomes with busulfan and melphalan compared with busulfan and cyclophosphamide in high risk patients autografted in first complete remission: A study from the acute leukemia working party of the EBMT

Autologous stem cell transplantation remains a clinical option to consolidate some adult patients with acute myelogenous leukemia (AML) in first complete remission (CR1). In a small cohort of patients, we have previously shown better outcomes following Busulfan and Melphalan (BUMEL) over Busulfan and Cyclophosphamide (BUCY). To identify the subpopulations that might get the highest benefit with BUMEL, we designed a larger study. All adult patients with primary AML and available cytogenetics, autografted from January 2000 to December 2016 in CR1, were included: 1137 patients received BUCY and 512 BUMEL. All factors differing in distribution between the 2 conditioning groups were introduced in multivariate analyzes. In a primary analysis, we found an interaction between conditioning and the poor risk group defined as poor cytogenetics and/or presence of the FLT3-ITD mutation. During analysis of the poor risk group, 176 patients received BUCY and 62 BUMEL. BUMEL was associated with a lower RI at 5 years (53% versus 69%, HR: 0.52, P = .002), a better Leukaemia-free survival (LFS) (42% versus 25%, HR: 0.54, P = .002) and a better OS (54% versus 36%, HR: 0.61, P = .02). During analysis of the non poor risk group, 961 patients received BUCY and 450 BUMEL. At 5 years, the RI was 50% and 47%, the LFS 45% and 48% and the OS 56% and 60% respectively, with no significant difference. We conclude that BUMEL is the preferable conditioning regimen for the poor risk leukemic patients, while in AML patients without poor risk cytogenetics or FLT3 both conditioning regimens are valid.

Distinct factors determine the kinetics of disease relapse in adults transplanted for acute myeloid leukaemia

BACKGROUND

Disease recurrence remains the major cause of death in adults with acute myeloid leukaemia (AML) treated using either intensive chemotherapy (IC) or allogenic stem cell transplantation (allo-SCT).

AIMS

The timely delivery of maintenance drug or cellular therapies represent emerging strategies with the potential to reduce relapse after both treatment modalities, but whilst the determinants of overall relapse risk have been extensively characterized the factors determining the timing of disease recurrence have not been characterized.

MATERIALS AND METHODS

We have therefore examined, using a series of sequential landmark analyses, relapse kinetics in a cohort of 2028 patients who received an allo-SCT for AML in CR1 and separately 570 patients treated with IC alone.

RESULTS

In the first 3 months after allo-SCT, the factors associated with an increased risk of relapse included the presence of the FLT3-ITD (P < 0.001), patient age (P = 0.012), time interval from CR1 to transplant (P < 0.001) and donor type (P = 0.03). Relapse from 3 to 6 months was associated with a higher white cell count at diagnosis (P = 0.001), adverse-risk cytogenetics (P < 0.001), presence of FLT3-ITD mutation (P < 0.001) and time interval to achieve first complete remission (P = 0.013). Later relapse was associated with adverse cytogenetics, mutated NPM1, absence of chronic graft-versus-host disease (GVHD) and the use of in vivo T-cell depletion. In patients treated with IC alone, the factors associated with relapse in the first 3 months were adverse-risk cytogenetics (P < 0.001) and FLT3-ITD status (P = 0.001). The factors predicting later relapse were the time interval from diagnosis to CR1 (P = 0.22) and time interval from CR1 to IC (P = 0.012).

DISCUSSION AND CONCLUSION

Taken together, these data provide novel insights into the biology of disease recurrence after both allo-SCT and IC and have the potential to inform the design of novel maintenance strategies in both clinical settings.

Impact of Donor Type in Patients with AML Given Allogeneic Hematopoietic Cell Transplantation After Low-Dose TBI-Based Regimen

Purpose: We assessed the impact of donor type in acute myeloid leukemia (AML) patients transplanted with 2 Gy total body irradiation (TBI)-based nonmyeloablative conditioning regimen.Patients and Methods: Data from 1,715 adult patients, with AML in CR1 or CR2 were included in this retrospective survey.Results: Donors consisted either of HLA-matched sibling donors (MSD, n = 701), 10/10 HLA-matched unrelated donors (MUD, n = 611), HLA-haploidentical donors (haplo, n = 112) or single or double umbilical cord bloods (CBT, n = 291). Chronic graft-versus-host disease (GVHD) was less frequent in CBT (28%) and in haplo (30%) patients than in MSD (50%) and MUD (51%) recipients (P < 0.001). Two-year incidence of relapse was 32%, 30%, 34%, and 34% in MSD, MUD, CBT and haplo patients, respectively (P = 0.7). Two-year overall (OS) and GVHD-free relapse-free survival (GRFS) were 59% and 29% in MSD patients, 56% and 39% in CBT recipients, 53% and 23% in MUD recipients, and 43% and 37% in haplo patients, respectively. In multivariate analyses, MUD patients had lower GRFS than MSD patients beyond day 100 (HR 1.3, P = 0.001) while CBT was associated with a better GRFS than MSD beyond day 100 (HR 0.6, P = 0.002).Conclusions: In this large cohort of AML patients transplanted following low-dose TBI-based conditioning, the relapse incidence was not affected by donor type suggesting that the intensity of GVL effects might be comparable with these four transplant approaches. Furthermore, CBT was associated with better GRFS beyond day 100 than MSD while the opposite was observed for MUD. Clin Cancer Res; 24(12); 2794-803. ©2018 AACR.

Update on current research into haploidentical hematopoietic stem cell transplantation

INTRODUCTION

Haploidentical stem cell transplantation (Haplo-SCT) is currently a suitable alternative worldwide for patients with hematological diseases, who lack human leukocyte antigen (HLA)-matched siblings or unrelated donors. Areas covered: This review summarizes the advancements in Haplo-SCT in recent years, primarily focusing on the global trends of haploidentical allograft, the comparison of outcomes between Haplo-SCT and other transplantation modalities, strategies for improving clinical outcomes, including donor selection, hematopoietic reconstitution promotion, and graft-versus-host disease, and relapse prevention/management, as well as the expanded indications of Haplo-SCT, such as severe aplastic anemia, myeloma and lymphoma. Expert commentary: Haploidentical allografts, including granulocyte colony-stimulating factor-based protocol and a post-transplant cyclophosphamide-based protocol, have been the mainstream strategy for Haplo-SCT. However, there are many unanswered questions in this field.

Effect of sorafenib on the outcomes of patients with FLT3-ITD acute myeloid leukemia undergoing allogeneic hematopoietic stem cell transplantation

BACKGROUND

The objective of this study was to evaluate the effect of sorafenib on the outcomes of patients with acute myeloid leukemia (AML) with FMS-like tyrosine kinase 3 (FLT3)-internal tandem duplication (ITD) undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT).

METHODS

A total of 144 patients with FLT3-ITD AML undergoing allo-HSCT between January 2012 and December 2015 were enrolled in this study. Depending on whether they were receiving sorafenib before transplantation or sorafenib maintenance after transplantation, patients were divided into 4 groups: patients receiving sorafenib before transplantation (group A; n = 36), patients receiving sorafenib after transplantation (group B; n = 32), patients receiving sorafenib both before and after transplantation (group C; n = 26), and patients receiving sorafenib neither before nor after transplantation (group D; n = 50). Outcomes were compared among these groups.

RESULTS

The 3-year relapse rates were 22.2%, 18.8%, 15.8%, and 46.1% for groups A, B, C, and D, respectively (P = .006). The 3-year overall survival (OS) rates were 74.9%, 78.1%, 84.6%, and 50.9%, respectively (P = .023), and the 3-year leukemia-free survival (LFS) rates were 69.4%, 78.1%, 80.4%, and 34.8%, respectively (P < .001). The relapse rate was higher and the LFS was shorter in group D versus groups A, B, and C. The OS in group D was shorter than the OS in group C but was similar to the OS in groups A and B. A multivariate analysis revealed that sorafenib before transplantation, sorafenib maintenance after transplantation, and their combined application were protective factors for a lower relapse rate (hazard ratios [HRs], 0.436 [P = .048], 0.431 [P = .046], and 0.173 [P = .002], respectively) and longer LFS (HRs, 0.322 [P = .010], 0.343 [P = .014], and 0.187 [P = .001], respectively).

CONCLUSIONS

Sorafenib before transplantation, sorafenib maintenance after transplantation, and their combined application all could improve the outcomes for patients with FLT3-ITD AML. Further study is needed to determine whether the use of sorafenib both before and after transplantation might be ideal. Cancer 2018;124:1954-63. © 2018 American Cancer Society.

The rocky road to personalized medicine in acute myeloid leukaemia

Acute myeloid leukaemia (AML) is a malignant disorder of the myeloid blood lineage characterized by impaired differentiation and increased proliferation of hematopoietic precursor cells. Recent technological advances have led to an improved understanding of AML biology but also uncovered the enormous cytogenetic and molecular heterogeneity of the disease. Despite this heterogeneity, AML is mostly managed by a 'one-size-fits-all' approach consisting of intensive, highly toxic induction and consolidation chemotherapy. These treatment protocols have remained largely unchanged for the past several decades and only lead to a cure in approximately 30-35% of cases. The advent of targeted therapies in chronic myeloid leukaemia and other malignancies has sparked hope to improve patient outcome in AML. However, the implementation of targeted agents in AML therapy has been unexpectedly cumbersome and remains a difficult task due to a variety of disease- and patient-specific factors. In this review, we describe current standard and investigational therapeutic strategies with a focus on targeted agents and highlight potential tools that might facilitate the development of targeted therapies for this fatal disease. The classes of agents described in this review include constitutively activated signalling pathway inhibitors, surface receptor targets, epigenetic modifiers, drugs targeting the interaction of the hematopoietic progenitor cell with the stroma and drugs that target the apoptotic machinery. The clinical context and outcome with these agents will be examined to gain insight about their optimal utilization.

Similar outcome of allogeneic stem cell transplantation after myeloablative and sequential conditioning regimen in patients with refractory or relapsed acute myeloid leukemia: A study from the Société Francophone de Greffe de Moelle et de Thérapie Cellulaire

Patients with acute myeloid leukemia (AML) in relapse or refractory to induction therapy have a dismal prognosis. Allogeneic hematopoietic stem cell transplantation is the only curative option. In these patients, we aimed to compare the results of a myeloablative transplant versus a sequential approach consisting in a cytoreductive chemotherapy followed by a reduced intensity conditioning regimen and prophylactic donor lymphocytes infusions. We retrospectively analyzed 99 patients aged 18-50 years, transplanted for a refractory (52%) or a relapsed AML not in remission (48%). Fifty-eight patients received a sequential approach and 41 patients a myeloablative conditioning regimen. Only 6 patients received prophylactic donor lymphocytes infusions. With a median follow-up of 48 months, 2-year overall survival was 39%, 95% confidence interval (CI) (24-53) in the myeloablative group versus 33%, 95% CI (21-45) in the sequential groups (P = .39), and 2-year cumulative incidence of relapse (CIR) was 57% versus 50% respectively (P = .99). Nonrelapse mortality was not higher in the myeloablative group (17% versus 15%, P = .44). In multivariate analysis, overall survival, CIR and nonrelapse mortality remained similar between the two groups. However, in multivariate analysis, sequential conditioning led to fewer acute grade II-IV graft versus host disease (GVHD) (HR for sequential approach = 0.37; 95% CI: 0.21-0.65; P < .001) without a significant impact on chronic GVHD (all grades and extensive). In young patients with refractory or relapsed AML, myeloablative transplant and sequential approach offer similar outcomes except for a lower incidence of acute GvHD after a sequential transplant.

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.

High-dose melphalan-based sequential conditioning chemotherapy followed by allogeneic haematopoietic stem cell transplantation in adult patients with relapsed or refractory acute myeloid leukaemia

Considering the unsatisfactory results of salvage therapies for patients with relapsed/refractory acute myeloid leukaemia (R/R-AML), their value before allogeneic haematopoietic stem cell transplantation (HSCT) remains questionable. However, direct allogeneic HSCT following established conditioning regimens applied in patients with R/R-AML during active disease has been equally disappointing. In this retrospective observational study, high-dose melphalan, as part of a sequential preparative regimen, followed by a total body irradiation (4 × 2 Gy)-based or a treosulfan-based dose-adapted conditioning therapy for allogeneic HSCT was administered to 292 adult patients (median age 56 years, range 17-74) with primary refractory (144 patients), secondary refractory (97 patients) or relapsed AML (51 patients). Overall survival rates at 3 years were 34%, 29% and 41%, respectively. Risk factors associated with an inferior survival were higher age, transplantation from a human leucocyte antigen-mismatched donor and high disease burden. Patients transplanted with blast infiltration <20% showed a notable survival rate of 51% at 3 years. In particular, patients with primary refractory AML showed a more favourable outcome when transplanted early during their disease course. Thus, high-dose melphalan-based sequential conditioning chemotherapy followed by an allogeneic HSCT is feasible and enables long-term remission to be achieved in a substantial proportion of patients with active R/R-AML.

Tyrosine kinase inhibitors and immune checkpoint blockade in allogeneic hematopoietic cell transplantation

Advances in the prevention of graft-versus-host disease (GVHD) and opportunistic infection have improved survival after allogeneic hematopoietic cell transplantation (allo-HCT) in the past decade. However, few inroads have been made into the treatment or prevention of relapse of the underlying malignancy for which allo-HCT is being performed. The introduction of US Food and Drug Administration-approved agents with significant activity in a variety of hematologic malignancies provides an opportunity to evaluate these interventions in the allo-HCT setting. Some of the most promising new agents include tyrosine kinase inhibitors (TKIs) directed at bcr-abl, kinase inhibitors targeting fms-like tyrosine kinase 3, and immune checkpoint inhibitors blocking both CTLA4 and PD-1. Data have emerged indicating potential efficacy of these agents in preventing or treating relapse, though definitive evidence remains elusive. However, potential toxicity can be considerable, highlighting the need for further clinical trials to define the therapeutic window. This review explores the immunologic and clinical consequence of treatment with both TKIs and checkpoint inhibitors in the peri- and post-allo-HCT setting.

Precision therapy for acute myeloid leukemia

Acute myeloid leukemia (AML) is a molecularly and clinically heterogeneous disease. Despite advances in understanding the pathogenesis of AML, the standard therapy remained nearly unchanged over the past three decades. With the poor survival for older patients and high relapse rate, multiple studies are ongoing to address this important issue. Novel therapies for AML, including the refinements of conventional cytotoxic chemotherapies and genetic and epigenetic targeted drugs, as well as immunotherapies, have been developed in recent years. Here, we present a mechanism-based review of some promising new drugs with clinical efficacy, focus on targeted drugs that are most potential to pave the road to success, and put forward the major challenges in promoting the precision therapy for AML.

Relatively favorable outcome after allogeneic stem cell transplantation for BCR-ABL1-positive AML: A survey from the acute leukemia working party of the European Society for blood and marrow transplantation (EBMT)

The aim of the study was to assess the role of allogeneic stem cell transplantation (SCT) in patients diagnosed with BCR-ABL1-positive acute myeloid leukemia (AML). Fifty-seven patients (median age, 48 years, range: 19-67) with BCR-ABL1 positive AML undergoing SCT were identified. The majority of the patients (70%) received a TKI before the transplant. At SCT 48 patients were in CR (45 in CR1), while 9 patients were transplanted in a more advanced stage of the disease. MRD was negative (BCR-ABL1/ABL < 10⁴ ) at time of SCT in 36.1% (14/40). After SCT, 16 (61.5%) out of 26 patients with MRD positive at transplantation reached MRD negativity. After a median follow-up of 6.3 years (0.7-14.2), NRM, RI, LFS, OS, and GRFS at 5 years were 18.1%, 37%, 44.2%, 53.8%, and 32.1%, respectively. The cumulative incidence of acute GvHD grade II-IV was 16.4%, incidence of chronic GvHD 24.9%, and of extensive cGvHD 21.4%, respectively. In patients who received SCT in CR1, 5-yr NRM, RI, LFS, OS, and GRFS were 15.9%, 36.4%, 46.5%, 59.4%, and 34.9%, respectively. Univariate analysis showed that age (<50 vs. ≥50 years) was associated with RI (5-yr: 22.7 vs. 50%), LFS (5-yr: 61.9 vs. 31.8%), and GRFS (5-yr: 52.4 vs. 18.2%), whereas MRD-negative status before SCT was associated with an improved GRFS (38.9 vs. 16.7%). We conclude that the outcome of patients <50 years of age with BCR-ABL1-positive AML receiving allogeneic SCT in CR is relatively favorable, possibly reflecting the beneficial effect of the use of TKI.

Improved prognosis with additional medium-dose VP16 to CY/TBI in allogeneic transplantation for high risk ALL in adults

Allogeneic hematopoietic stem cell transplantation (HSCT) with the conventional cyclophosphamide and total body irradiation (CY/TBI) regimen is an essential therapeutic strategy for acute lymphoblastic leukemia (ALL) in adults. Medium-dose etoposide (VP16, 30-40 mg/kg) can be added to intensify this CY/TBI regimen and reduce relapse; however, differences in prognosis between the VP16/CY/TBI and CY/TBI regimens have not yet been fully analyzed. We conducted a retrospective cohort study using a Japanese transplant registry database to compare the prognosis between the VP16/CY/TBI (VP16, total 30-40 mg/kg) (N = 376) and CY/TBI (N = 1178) regimens in adult patients with ALL transplanted at complete remission (CR) between January 1, 2000 and December 31, 2014. Our analyses indicated that VP16/CY/TBI significantly reduced relapse compared with CY/TBI (risk ratio, 0.75; 95% confidence interval [CI], 0.56-1.00; P = .05) with a corresponding improvement in leukemia-free survival (hazard ratio [HR], 0.76; 95%CI, 0.62-0.93; P = .01), particularly in patients transplanted at CR1 with advanced-risk (positive minimal residual disease, presence of poor-risk cytogenetics, or an initial elevated leukocyte count) (HR, 0.75; 95%CI, 0.56-1.00; P = .05) or those transplanted beyond CR2 (HR, 0.58; 95%CI, 0.39-0.88; P = .01). The addition of VP16 did not increase post-transplant complications or nonrelapse mortality (HR, 0.88; 95%CI, 0.65-1.18; P = .38). This study is the first to reveal the efficacy of the addition of medium-dose VP16 to CY/TBI in high-risk ALL. To establish new myeloablative conditioning regimens including VP16, a large-scale prospective study is necessary.

The Hematopoietic Cell Transplant Pharmacist: Roles, Responsibilities, and Recommendations from the ASBMT Pharmacy Special Interest Group

Pharmacists are increasingly recognized as an essential member of the multidisciplinary team for hematopoietic cell transplant (HCT) patients. However, until recently, their educational background, required training, and potential roles have not been well described. Therefore, the purpose of this manuscript is to provide supporting evidence for the HCT Clinical Pharmacist Role Description, which has been endorsed by several organizations including the American Society for Blood and Marrow Transplantation. This document provides justification for the various roles pharmacists fulfill with respect to medication management, transitions of care, patient and provider education, policy development, quality improvement, and research. Furthermore, evidence supporting the value, financially and otherwise, HCT pharmacists provide is reviewed. Pharmacists in the HCT setting are encouraged to report on novel practice models and potential impact of their services to increase awareness and utilization of HCT pharmacists.

Allogeneic stem cell transplantation benefits for patients ≥ 60 years with acute myeloid leukemia and FLT3 internal tandem duplication: a study from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Intermediate-risk cytogenetic acute myeloid leukemia with an internal tandem duplication of FLT3 (FLT3-ITD) is associated with a high risk of relapse, and is now a standard indication for allogeneic stem cell transplantation. Nevertheless, most studies supporting this strategy have been performed in young patients. To address the benefit of allogeneic transplantation in the elderly, we made a selection from the European Society for Blood and Marrow Transplantation registry of de novo intermediate-risk cytogenetic acute myeloid leukemia harboring FLT3-ITD in patients aged 60 or over and transplanted from a related or unrelated donor between January 2000 and December 2015. Two hundred and ninety-one patients were identified. Most patients received a reduced-intensity conditioning (82%), while donors consisted of an unrelated donor in 161 (55%) patients. Two hundred and twelve patients received their transplantation in first remission, 37 in second remission and 42 in a more advanced stage of the disease. The 2-year leukemia-free survival rate was 56% in patients in first remission, 22% in those in second remission and 10% in patients with active disease, respectively (P<0.005). Non-relapse mortality for the entire cohort was 20%. In multivariate analysis, disease status at transplantation was the most powerful predictor of worse leukemia-free survival, graft-versus-host disease and relapse-free survival, and overall survival. In this elderly population, age was not associated with outcome. Based on the current results, allogeneic transplantation translates into a favorable outcome in fit patients ≥ 60 with FLT3-ITD acute myeloid leukemia in first remission, similarly to current treatment recommendations for younger patients.

The role of targeted therapy in the management of patients with AML

Drug therapy for acute myeloid leukemia (AML) is finally undergoing major changes in 2017. This is due to the US Food and Drug Administration's approval of several new, targeted agents (midostaurin, enasidenib, and gemtuzumab ozogamicin). Paired with the recent approval of a novel liposomal formulation of daunorubicin/cytarabine (CPX-351/Vyxeos), the standard of care is changing rapidly in AML for subgroups. This review will focus on currently approved agents and promising novel agents in development and will highlight controversial areas in targeted treatment.

Glioblastoma and acute myeloid leukemia: malignancies with striking similarities

Acute myeloid leukemia (AML) and glioblastoma (GB) are two malignancies associated with high incidence of treatment refractoriness and generally, uniformly poor survival outcomes. While the former is a hematologic (i.e. a "liquid") malignancy and the latter a solid tumor, the two diseases share both clinical and biochemical characteristics. Both diseases exist predominantly in primary (de novo) forms, with only a small subset of each progressing from precursor disease states like the myelodysplastic syndromes or diffuse glioma. More importantly, the primary and secondary forms of each disease are characterized by common sets of mutations and gene expression abnormalities. The primary versions of AML and GB are characterized by aberrant RAS pathway, matrix metalloproteinase 9, and Bcl-2 expression, and their secondary counterparts share abnormalities in TP53, isocitrate dehydrogenase, ATRX, inhibitor of apoptosis proteins, and survivin that both influence the course of the diseases themselves and their progression from precursor disease. An understanding of these shared features is important, as it can be used to guide both the research about and treatment of each.

[Preventative and therapeutic relapse strategies after allogeneic hematopoietic stem cell transplantation: Guidelines from the Francophone society of bone marrow transplantation and cellular therapy (SFGM-TC)]

Disease relapse remains the first cause of mortality of hematological malignancies after allogeneic hematopoietic stem cell transplantation (allo-HCT). The risk of recurrence is elevated in patients with high-risk cytogenetic or molecular abnormalities, as well as when allo-HCT is performed in patients with refractory disease or with persistent molecular or radiological (PET-CT scan) residual disease. Within the frame of the 7th annual workshops of the francophone society for bone marrow transplantation and cellular therapy, the working group reviewed the literature in order to elaborate unified guidelines for the prevention and treatment of relapse after allo-HCT. For high risk AML and MDS, a post transplant maintenance strategy is possible, using hypomethylating agents or TKI anti-FLT3 when the target is present. For Philadelphia positive ALL, there was a consensus for the use of post-transplant TKI maintenance. For lymphomas, there are no strong data on the use of post-transplant maintenance, and hence a preemptive strategy is recommended based on modulation of immunosuppression, close follow-up of donor chimerism, and donor lymphocytes infusion. For multiple myeloma, even though the indication of allo-HCT is controversial, our recommendation is post transplant maintenance using bortezomib, due to its a good toxicity profile without increasing the risk of GVHD.

The role of targeted therapy in the management of patients with AML

Drug therapy for acute myeloid leukemia (AML) is finally undergoing major changes in 2017. This is due to the US Food and Drug Administration's approval of several new, targeted agents (midostaurin, enasidenib, and gemtuzumab ozogamicin). Paired with the recent approval of a novel liposomal formulation of daunorubicin/cytarabine (CPX-351/Vyxeos), the standard of care is changing rapidly in AML for subgroups. This review will focus on currently approved agents and promising novel agents in development and will highlight controversial areas in targeted treatment.

Midostaurin/PKC412 for the treatment of newly diagnosed FLT3 mutation-positive acute myeloid leukemia

INTRODUCTION

Acute myeloid leukemia (AML) is an aggressive hematologic malignancy with inadequate treatment options. Approximately one-third of cases have a FLT3-ITD or FLT3-TKD mutation which leads to constitutive tyrosine kinase activation which contributes to leukemogenesis. The FLT3-ITD mutation is associated with a particularly poor prognosis. Midostaurin is a multi-kinase inhibitor active against the FLT3 receptor. Midostaurin was approved by the US FDA in April 2017 for treatment of newly diagnosed FLT3-mutant AML in combination with chemotherapy. Areas covered: Standard treatment of FLT3-mutant AML and outcomes. Early clinical development of midostaurin including pharmacokinetics and metabolism. The development of midostaurin in FLT3-mutant AML is then outlined including review of the phase I, II, and III trials of midostaurin as a single agent and in combination with chemotherapy. Expert commentary: The approval of midostaurin represents the first new therapy for AML in several decades. It is also the first targeted therapy approved for AML. Future studies will focus on defining mechanisms of resistance to midostaurin as well as establishing the role of midostaurin in combination with hypomethylating agents and as maintenance therapy. Second generation, more potent and selective FLT3 inhibitors are also in development; these agents need to be compared to midostaurin.

Targeted therapies in Acute Myeloid Leukemia: a focus on FLT-3 inhibitors and ABT199

INTRODUCTION

Acute myeloid leukemia (AML) remains a therapeutic challenge. Despite ongoing research, the standard therapy for AML has not changed significantly in the past four decades. With the identification of cytogenetic and molecular abnormalities, several promising therapeutic agents are currently being investigated. FLT3 mutation is a well-recognized target seen in 30% of the cytogenetically normal AML. More recently, the BCL2 family of anti-apoptotic proteins have also generated great interest as a therapeutic target. Areas covered: This review will cover the role of FLT3 inhibitors in AML, discussing trials in relapsed/refractory AML and in the frontline setting, including the young and elderly patient population. Toxicities and potential mechanism of resistance will also be covered. In addition, most current studies demonstrating the role of BCL-2 inhibitors namely ABT-199/venetoclax in AML will also be discussed. Expert commentary: AML is one of the most heterogeneous group of hematological malignancies. It remains a therapeutic challenge with limited therapeutic progress despite ongoing research. With the identification of different mutations in AML, several drugs are being evaluated in clinical trials. Targeted agents such as FLT3 inhibitors and BH3 mimetics so far have shown promising results in terms of response and toxicity profile.

Alternative Donor Graft Sources for Adults with Hematologic Malignancies: A Donor for All Patients in 2017!

Hematopoietic stem cell transplant (HSCT) is potentially curative for a wide variety of malignant diseases, including acute and leukemias, lymphoma, and myelodysplasia. Choice of a stem cell donor is dependent on donor availability, donor compatibility and health, recipient disease type, and recipient condition. Current sources of stem cell donation for HSCT are matched sibling donors (MSDs), matched unrelated donors (MUDs), 1-antigen mismatched unrelated donors (MMUDs), haploidentical donors (haplo), and umbilical cord blood (UCB) units. Historically, preferred donors for HSCT have been human leukocyte antigen (HLA)-matched sibling donors; however, only about 30% of U.S. patients will have a MSD available. The majority of patients referred for HSCT will require an alternative donor graft: MUD, MMUD, UCB, or haplo. The likelihood of finding a MUD varies depending on the ethnicity of the recipient. White Caucasians of European descent have the greatest chance of finding a MUD. Chances of finding a MUD are significantly less for African-American or Hispanic recipients due to HLA polymorphisms. Therefore, MMUD, UCB, and haplo donor graft sources expand the donor pool for recipients who do not have a MSD or MUD available. Given the variety of different donor stem cell sources available today, nearly every patient who needs an allogeneic HSCT has a potential donor in 2017. All transplant-eligible patients with hematologic malignancies should be evaluated by a transplant center to determine if HSCT is a viable treatment option for their underlying disease process.

IMPLICATIONS FOR PRACTICE

The goal of this review is to increase the awareness of oncology practitioners to the availability of alternative donor stem cell transplants for patients with hematologic malignancies. Despite new agents, stem cell transplant remains the only curative therapy for many patients with acute and chronic leukemia, myelodysplasia, and lymphoma. Given the variety of different donor stem cell sources available today, nearly every patient who needs an allogeneic stem cell transplant will have a donor.

Umbilical Cord Blood Transplantation: Challenges and Future Directions

Since the first successful allogeneic transplants performed in Seattle 50 years ago, the field of transplantation has evolved considerably, with improvements in human leukocyte antigen typing, patient selection, reduced intensity regimens, and graft-versus-host disease prophylaxis. A major breakthrough has been the availability of more donor options, first via the National Marrow Donor Program-Be the Match [Biol Blood Marrow Transplant 2008;14:2-7]. Then, in the 1990s, unrelated umbilical cord blood transplantation became available, first for children and then for adults [New Engl J Med 1996;35:157-166]. More recently mismatched unrelated transplants and haploidentical donor options became available [Blood 2011;118:282-288]. In 2017, there is a donor for almost every patient who needs a transplant. In this review, we will discuss the state of the science (and art) of cord blood transplant, focusing on successes, challenges, and future directions. Stem Cells Translational Medicine 2017;6:1312-1315.

Efficacy and feasibility of sorafenib as a maintenance agent after allogeneic hematopoietic stem cell transplantation for Fms-like tyrosine kinase 3-mutated acute myeloid leukemia

BACKGROUND

Sorafenib has shown encouraging results in patients with Fms-like tyrosine kinase 3 (FLT3)-positive acute myeloid leukemia. Its role after allogeneic stem cell transplantation (HSCT) has been reported in a few cases with encouraging results.

METHODS

The authors describe the use of sorafenib as a maintenance agent after HSCT in 27 patients with FLT3-positive acute myeloid leukemia.

RESULTS

The median age of the patients was 46 years (range, 15-57 years). Sorafenib was introduced at a median of 70 days (range, 29-337 days) after HSCT. The median treatment duration was 8.4 months (range, 0.2-46 months). Eleven patients experienced treatment toxicities, mainly of grade 1 to 2 (graded according to the National Cancer Institute Common Toxicity Criteria [version 4.0]). Dose reduction or withdrawal was required in 4 patients and 4 patients, respectively. The persistence of toxicity prompted treatment withdrawal in 1 patient. Clinical improvement followed dose modifications. Thirteen patients experienced chronic graft-versus-host disease (limited in 9 patients and extensive in 4 patients), resulting in dose reduction in 5 patients followed by withdrawal in 1 of these individuals. At a median follow-up of 18 months (range, 4-48 months), 25 patients were alive (all of whom were in complete molecular remission) and 18 were still receiving treatment, with 1-year overall survival and progression-free survival rates of 92% ± 6% and 92% ± 5%, respectively.

CONCLUSIONS

Sorafenib treatment after HSCT appears to be feasible and highly effective with dose individualization according to patient tolerability. Further analysis is needed to evaluate the immunomodulating role of sorafenib after HSCT. The data from the current support prospective controlled trials of sorafenib after HSCT. Cancer 2017;123:2867-74. © 2017 American Cancer Society.

FLT3 inhibitors: clinical potential in acute myeloid leukemia

Acute myeloid leukemia (AML) is an aggressive hematopoietic malignancy that is cured in as few as 15%–40% of cases. Tremendous improvements in AML prognostication arose from a comprehensive analysis of leukemia cell genomes. Among normal karyotype AML cases, mutations in the FLT3 gene are the ones most commonly detected as having a deleterious prognostic impact. FLT3 is a transmembrane tyrosine kinase receptor, and alterations of the FLT3 gene such as internal tandem duplications (FLT3-ITD) deregulate FLT3 downstream signaling pathways in favor of increased cell proliferation and survival. FLT3 tyrosine kinase inhibitors (TKI) emerged as a new therapeutic option in FLT3-ITD AML, and clinical trials are ongoing with a variety of TKI either alone, combined with chemotherapy, or even as maintenance after allogenic stem cell transplantation. However, a wide range of molecular resistance mechanisms are activated upon TKI therapy, thus limiting their clinical impact. Massive research efforts are now ongoing to develop more efficient FLT3 TKI and/or new therapies targeting these resistance mechanisms to improve the prognosis of FLT3-ITD AML patients in the future.

Targeting FLT3 Signaling in Childhood Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is the second most common leukemia of childhood and is associated with high rates of chemotherapy resistance and relapse. Clinical outcomes for children with AML treated with maximally intensive multi-agent chemotherapy lag far behind those of children with the more common acute lymphoblastic leukemia, demonstrating continued need for new therapeutic approaches to decrease relapse risk and improve long-term survival. Mutations in the FMS-like tyrosine kinase-3 receptor gene (FLT3) occur in approximately 25% of children and adults with AML and are associated with particularly poor prognoses. Identification and development of targeted FLT3 inhibitors represents a major precision medicine paradigm shift in the treatment of patients with AML. While further development of many first-generation FLT3 inhibitors was hampered by limited potency and significant toxicity due to effects upon other kinases, the more selective second- and third-generation FLT3 inhibitors have demonstrated excellent tolerability and remarkable efficacy in the relapsed/refractory and now de novo FLT3-mutated AML settings. While these newest and most promising inhibitors have largely been studied in the adult population, pediatric investigation of FLT3 inhibitors with chemotherapy is relatively recently ongoing or planned. Successful development of FLT3 inhibitor-based therapies will be essential to improve outcomes in children with this high-risk subtype of AML.