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

Precision medicine in AML: overcoming resistance

The development of molecularly targeted therapy for acute myeloid leukemia is progressing at an accelerated pace. Therapies targeting FLT3, IDH1, IDH2, and BCL2 have been approved in the last 5 years. As we exploit these biological vulnerabilities, various mechanisms of resistance arise. Emergence of competing clones with different genetic drivers and acquisition of constitutional mutations in the target renders therapies ineffective, and enzymatic isoform changes can lead to reappearance of the disease phenotype. Understanding the timing and circumstances of resistance origination will allow clinicians to develop combinatorial and sequential therapeutic approaches to deepen responses and improve survival. The objective of this review is to illustrate the biological underpinnings of each therapy and the landscape of resistance mechanisms and discuss strategies to overcome on- and off-target resistance.

Survival after allogeneic transplantation according to pretransplant minimal residual disease and conditioning intensity in patients with acute myeloid leukemia

Background

The measurement of minimal residual disease (MRD) by multiparametric flow cytometry (MFC) before hematopoietic stem cell transplantation (HSCT) in patients with acute myeloid leukemia (AML) is a powerful prognostic factor. The interaction of pretransplant MRD and the conditioning intensity has not yet been clarified.

Objective

The aim of this study is to analyze the transplant outcomes of patients with AML who underwent HSCT in complete remission (CR), comparing patients with positive MRD (MRD+) and negative MRD (MRD-) before HSCT, and the interaction between conditioning intensity and pre-HSCT MRD.

Study design

We retrospectively analyzed the transplant outcomes of 118 patients with AML who underwent HSCT in CR in a single institution, comparing patients with MRD+ and MRD- before HSCT using a cutoff of 0.1% on MFC, and the interaction between conditioning intensity and pre-HSCT MRD.

Results

Patients with MRD+ before HSCT had a significantly worse 2-year (2y) event-free survival (EFS) (56.5% vs. 32.0%, p = 0.018) than MRD- patients, due to a higher cumulative incidence of relapse (CIR) at 2 years (49.0% vs. 18.0%, p = 0.002), with no differences in transplant-related mortality (TRM) (2y-TRM, 19.0% and 25.0%, respectively, p = 0.588). In the analysis stratified by conditioning intensity, in patients who received MAC, those with MRD- before HSCT had better EFS (p = 0.009) and overall survival (OS) (p = 0.070) due to lower CIR (p = 0.004) than MRD+ patients. On the other hand, the survival was similar in reduced intensity conditioning (RIC) patients regardless of the MRD status.

Conclusions

Patients with MRD+ before HSCT have worse outcomes than MRD- patients. In patients who received MAC, MRD- patients have better EFS and OS due to lower CIR than MRD+ patients, probably because they represent a more chemo-sensitive group. However, among RIC patients, results were similar regardless of the MRD status.

Allogeneic hematopoietic cell transplantation for patients with AML aged 70 years or older in first remission. A study from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation (EBMT)

Accessibility to allogeneic hematopoietic cell transplantation (HCT) programs for older patients is growing constantly. We report on the clinical outcomes of a group of 701 adults aged ≥70 years, with acute myeloid leukemia (AML) in first complete remission (CR1), who received a first HCT, from HLA-matched sibling donors (MSD), 10/10 HLA-matched unrelated donors (UD), 9/10 HLA-mismatched unrelated donors (mUD) or haploidentical (Haplo) donors. The 2-year overall survival (OS) was 48.1%, leukemia-free survival (LFS) 45.3%, relapse incidence (RI) 25.2%, non-relapse mortality (NRM) 29.5% and GVHD-free, relapse-free survival (GRFS), 33.4%. Compared to MSD, patients transplanted from Haplo and UD presented lower RI (HR 0.46, 95% CI 0.25-0.8, p = 0.02 and HR 0.44, 95% CI: 0.28-0.69, p = 0.001, respectively); this translated into prolonged LFS for Haplo (HR 0.62, 95% CI: 0.39-0.99, p = 0.04). Patients transplanted from mUD exhibited the highest NRM incidence (HR 2.33, 95% CI: 1.26-4.31, p = 0.007). HCT in selected adult CR1 AML patients >70 years is feasible and could be associated with good clinical outcomes. Prospective clinical trials are warranted.

Old age: the crown of life, our play's last act. Question and answers on older patients undergoing allogeneic hematopoietic cell transplantation

PURPOSE OF REVIEW

Several studies showed that age alone should not be used as an arbitrary parameter to exclude patients from allogeneic hematopoietic cell transplantation (HCT). The accessibility to allogeneic HCT programs for older patients with hematological diseases is growing up constantly. The Center for International Blood and Marrow Transplant Research has recently shown that over 30% of allogeneic HCT recipients are at least 60 years old and that nearly 4% are aged 70 or more. Historically, the use of allogeneic HCT among elderly patients has been limited by age restrictions, reflecting physicians' concerns regarding prohibitive transplant-related mortality and HCT-associated morbidity.

RECENT FINDINGS

The introduction of reduced intensity/toxicity conditioning regimens has allowed transplant Centers to carry out allogeneic HCT on patients previously considered not ideal candidates. The integration of specific risk scores could lead to better capture mental and physical frailties of older patients. Older adults less frequently have available medically fit siblings, able to donate, so, unrelated donors, familial haploidentical donors or umbilical cord blood grafts could potentially abrogate such a difficulty, allowing the curative potential of allogeneic HCT.

SUMMARY

The appropriate assessing of allogeneic HCT feasibility for elderly patients should be the resonate application of different clinical and biological principles.

Cytogenetic risk classification maintains its prognostic significance in transplanted FLT3-ITD mutated acute myeloid leukemia patients: On behalf of the acute leukemia working party/European society of blood and marrow transplantation

FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) mutational status is a pivotal prognosticator in acute myeloid leukemia (AML) patients and significantly increases the risk of disease relapse. However, it remains unclear whether in FLT3-ITD patients referred for allogeneic stem cell transplantation (allo-SCT), baseline cytogenetics significantly impacts clinical outcome. Using the European Society of Blood and Marrow Transplantation registry, we performed a retrospective analysis of 1631 FLT3-ITD AML patients who underwent allo-SCT with the aim of determining the influence of cytogenetic risk category on patient outcomes. Median patient age was 49 years and median follow-up duration was 36 months. Two-year leukemia-free survival (LFS) and incidence of relapse were 54% and 31.6%, respectively. Non-relapse mortality was experienced by 14.4% with a 2-year overall survival (OS) of 60.1%. On multivariate analysis, LFS was significantly lower in patients with intermediate and adverse risk cytogenetics compared with those with favorable risk cytogenetics, (hazard ratio [HR] = 1.48, 95% confidence interval [CI], 1.06-2.06; p = .02), and (HR = 01.65, 95% CI, 1.13-2.40; p = .009), respectively. OS was significantly lower in patients with adverse risk cytogenetics compared with patients with favorable risk cytogenetics (HR = 1.74, 95% CI, 1.16-2.61; p = .008) with a trend toward lower OS in patients with intermediate risk cytogenetics compared to those with favorable risk cytogenetics (HR = 1.43, 95% CI, 1.00-2.05; p = .052). In addition, adverse risk patients and intermediate risk patients experienced higher relapse rates compared with favorable risk patients (HR = 1.83, 95% CI, 1.13-2.94; p = .013 and HR = 1.82, 95% CI, 1.19-2.77; p = .005). Overall, cytogenetic studies aid in refinement of risk stratification in transplanted FLT3-ITD AML patients.

Impact of FLT3 internal tandem duplication and NPM1 mutations in acute myeloid leukemia treated with allogeneic hematopoietic cell transplantation

BACKGROUND AIMS

The internal tandem duplication of FLT3 (FLT3^ITD) and NPM1 mutations (NPM1^mut) are well-established prognostic factors in cytogenetically intermediate-risk acute myeloid leukemia (AML) when treated with chemotherapy alone. However, their prognostic value in the setting of allogeneic hematopoietic cell transplantation (HCT) is controversial.

METHODS

FLT3 and NPM1 mutational status was determined at diagnosis using single-gene polymerase chain reaction or next-generation sequencing in 247 adult patients with cytogenetically intermediate-risk AML who underwent myeloablative HCT. Multivariate Fine-Gray and Cox regression was used to analyze the cumulative incidence of relapse (CIR), relapse-free survival (RFS) and overall survival (OS).

RESULTS

FLT3^ITD and NPM1^mut were present in 74 of 247 (30%) and 79 of 247 (32%) patients, respectively. There was no significant difference between patients without a FLT3^ITD or NPM1^mut (FLT3^NONITD/NPM1^WT) and patients with a FLT3^ITD mutation alone (FLT3^ITD/NPM1^WT) with regard to CIR (P = 0.60), RFS (P = 0.91) or OS (P = 0.66). Similarly, there was no significant difference between FLT3^NONITD/NPM1^WT and FLT3^NONITD/NPM1^mut patients with regard to CIR (P = 0.70), RFS (P = 0.75) or OS (P = 0.95). The presence of a concurrent mutation in NPM1 did not appear to modify the impact of having a FLT3^ITD mutation.

CONCLUSIONS

In contrast to chemotherapy-only treatment, FLT3 and NPM1 mutational status does not appear to predict outcomes in patients with cytogenetically intermediate-risk AML following HCT. These results suggest that HCT may ameliorate the poor prognostic effect of FLT3^ITD mutation and that HCT should be considered over chemotherapy-only treatment in FLT3^ITD-mutated AML.

Cost-effectiveness of gilteritinib for relapsed/refractory FLT3mut+ acute myeloid leukemia

BACKGROUND: Patients with relapsed or refractory (R/R) acute myeloid leukemia (AML) and confirmed feline McDonough sarcoma (FMS)-like tyrosine kinase 3 gene mutations (FLT3^mut+) have a poor prognosis and limited effective treatment options. Gilteritinib is the first targeted therapy approved in the United States and Europe for R/R FLT3^mut+ AML with significantly improved efficacy compared with existing treatments. OBJECTIVE: To evaluate gilteritinib against salvage chemotherapy (SC) and best supportive care (BSC) over a lifetime horizon among adult patients with R/R FLT3^mut+ AML from a US third-party payer's perspective. METHODS: The model structure of this cost-effectiveness analysis included a decision tree to stratify patients based on their hematopoietic stem cell transplantation (HSCT) status, followed by 2 separate 3-state partitioned survival models to predict the long-term health status conditional on HSCT status. The ADMIRAL trial data and literature were used to predict probabilities of patients being in different health states until a conservative cure point at year 3. Afterwards, living patients followed the survival outcomes of long-term survivors with AML. Model inputs for utilities, medical resource use, and costs were based on the ADMIRAL trial, published literature, and public sources. All costs were inflated to 2019 US dollars (USD). Total incremental costs (in 2019 USD), life-years (LYs), quality-adjusted LYs (QALYs), and incremental cost-effectiveness ratios (ICERs) were calculated. Deterministic sensitivity analyses and probabilistic sensitivity analyses were performed. RESULTS: Over a lifetime horizon with a 3.0% annual discount rate, the base-case model estimated that gilteritinib led to an increase of 1.29 discounted QALYs at an additional cost of $148,106 vs SC, corresponding to an ICER of $115,192 per QALY; for BSC, results were an increase of 2.32 discounted QALYs, $249,674, and $107,435, respectively. The base-case findings were robust in sensitivity analyses. The estimated probabilities of gilteritinib being cost-effective vs SC and BSC were 90.5% and 99.8%, respectively, in the probabilistic sensitivity analyses, based on a willingness-to-pay threshold of $150,000 per QALY. CONCLUSIONS: Gilteritinib is a cost-effective novel treatment for patients with R/R FLT3^mut+ AML in the United States. DISCLOSURES: This work was supported by Astellas Pharma, Inc., which was involved in all stages of the research and manuscript development. Garnham, Pandya, and Shah are employees of Astellas and hold stock/stock options. Zeidan consulted and received personal fees/honoraria and research funding from Astellas. Zeidan also has received research funding from Celgene/BMS, Abbvie, Astex, Pfizer, Medimmune/AstraZeneca, Boehringer-Ingelheim, Trovagene/Cardiff Oncology, Incyte, Takeda, Novartis, Amgen, Aprea, and ADC Therapeutics; has participated in advisory boards; has consulted with and/or received honoraria from AbbVie, Otsuka, Pfizer, Celgene/BMS, Jazz, Incyte, Agios, Boehringer-Ingelheim, Novartis, Acceleron, Daiichi Sankyo, Taiho, Seattle Genetics, BeyondSpring, Cardiff Oncology, Takeda, Ionis, Amgen, Janssen, Syndax, Gilead, Kura, Aprea, Lox Oncology, Genentech, Servier, Jasper, Tyme, and Epizyme; has served on clinical trial committees for Novartis, Abbvie, Geron, Gilead, Kura, Lox Oncology, BioCryst, and Celgene/BMS; and has received travel support for meetings from Pfizer, Novartis, and Cardiff Oncology. Qi and Yang are employees of Analysis Group, Inc., which received consulting fees from Astellas for work on this study. Part of this material was presented at the American Society of Hematology (ASH) Annual Meeting; December 7-10, 2019; Orlando, FL.

Single cord blood transplantation for acute myeloid leukemia patients aged 60 years or older: a retrospective study in Japan

The availability of alternative donor sources could allow elderly patients to receive allogeneic hematopoietic cell transplantation (HCT). We retrospectively evaluated the outcomes of single-unit cord blood transplantation (CBT) in 1577 patients aged ≥60 years with acute myeloid leukemia (AML) in Japan between 2002 and 2017. In total, 990 (63%) patients were not in complete remission (CR) at the time of CBT. A myeloablative conditioning regimen (52%) and calcineurin inhibitor (CI) + mycophenolate mofetil (MMF)-based graft-versus-host disease (GVHD) prophylaxis (45%) were more commonly used. With a median follow-up for survivors of 31 months, the probability of overall survival and the cumulative incidence of leukemia-related mortality at 3 years was 31% and 29%, respectively. The cumulative incidence of non-relapse mortality (NRM) at 100 days and 3 years were 24% and 41%, respectively. The cumulative incidences of grade II-IV and grade III-IV acute GVHD at 100 days and extensive chronic GVHD at 2 years were 44%, 16%, and 14%, respectively. The cumulative incidence of neutrophil engraftment was 80% at 42 days. Results of multivariate analysis indicated that the following factors were significantly associated with higher overall mortality: performance status ≥1, hematopoietic cell transplantation-specific comorbidity index ≥3, adverse cytogenetics, extramedullary disease at diagnosis, and non-CR status at CBT. By contrast, female sex, HLA disparities ≥2, mycophenolate mofetil-based GVHD prophylaxis, and recent CBT were significantly associated with lower overall mortality. In conclusion, single CBT offers a curative option for AML patients aged ≥60 years with careful patient selection.

Pre-transplant FLT3/ITD status predicts outcome in FLT3-mutated acute myeloid leukemia following allogeneic stem cell transplantation

Acute myeloid leukemia (AML) with fetal liver tyrosine kinase 3 (FLT3) internal tandem duplication (ITD) is associated with poor prognosis, and allogeneic stem cell transplantation (Allo-SCT) seems to be the preferred therapeutic approach. However, the predictors of post-transplant outcomes were not well-defined. The aim of the study was to evaluate the significance of FLT3/ITD mutation by polymerase chain reaction as minimal residual disease (MRD) marker of outcomes after transplantation. We identified 43 patients (28 females and 15 males) with FLT3-mutated AML at the median age of 45 years who were allografted between 2009 and 2019. Hematological status at transplant was as follows: the first complete remission (CR1) in 29 patients, CR2 in 5, and 9 patients were transplanted in marrow aplasia (MA). Twenty-seven patients were FLT3 MRD negative at transplant. Median time from diagnosis to transplant was 16.7 months. Post-allograft CR rate was 88%. The relapse incidence (RI) was lower for patients who were FLT3 MRD negative at transplant when compared with those with FLT3 MRD positivity (41% vs 59%; p = 0.01). The patients who eradicated FLT3/ITD at day + 30 after transplant had lower RI than those with detectable FLT3/ITD (23% vs 76%; p = <0.001). The 2-year LFS and OS were 53% and 54%, with the median OS and LFS of 28 months and 27 months, respectively. Patients with CR1/2 and FLT3 MRD(-) had a 2-year OS of 80%. The FLT3 MRD negativity at transplant prolonged LFS in multivariate analysis (HR 5.3 95%CI 1.97-14.2); p < 0.001), whereas FLT3 MRD negativity and unrelated donor predicted favorable OS.

Allogeneic stem cell transplantation in AML with t(6;9)(p23;q34);DEK-NUP214 shows a favourable outcome when performed in first complete remission

Acute myeloid leukaemia (AML) with t(6;9)(p23;q34) is a poor-risk entity, commonly associated with FLT3-ITD (internal tandem duplication). Allogeneic stem-cell tranplantation (allo-SCT) is recommended, although studies analysing the outcome of allo-SCT in this setting are lacking. We selected 195 patients with t(6;9) AML, who received a first allo-SCT between 2000 and 2016 from the EBMT (European Society for Blood and Marrow Transplantation) registry. Disease status at time of allo-SCT was the strongest independent prognostic factor, with a two-year leukaemia-free survival and relapse incidence of 57% and 19% in patients in CR1 (first complete remission), 34% and 33% in CR2 (second complete remission), and 24% and 49% in patients not in remission, respectively (P < 0·001). This study, which represents the largest one available in t(6;9) AML, supports the recommendation to submit these patients to allo-SCT in CR1.

Comprehensive prognostic scoring systems could improve the prognosis of adult acute myeloid leukemia patients

Acute myeloid leukemia (AML) is a heterogeneous malignancy characterized by a dismal outcome. To enable better outcomes, it is necessary to develop individual therapies based on risk stratification. In the present study, we established two new comprehensive prognostic scoring systems (CPSS) for overall survival (OS) and relapse-free survival (RFS) using the Cox proportional hazards regression, CPSS integrated and weighted age, AML type, lactic dehydrogenase (LDH), ECOG score, cytogenetics, and gene mutations. We divided patients into three risk groups-low-, intermediate-, and high-risk-with 1-year OS rates of 100.0%, 82.9%, and 38.2%, respectively (p < 0.0001), and patients undergoing complete remission (CR) were also separated into low-risk, intermediate-risk, and high-risk groups, with 1-year RFS rates of 87.7%, 58.4%, and 30.2%, respectively (p < 0.0001). We conclude that CPSS that integrate clinical characteristics, cytogenetic abnormalities, and gene mutations may improve the stratification of AML patients.

Novel treatments for relapsed/refractory acute myeloid leukemia with FLT3 mutations

Introduction: Mutations in the gene encoding for the FMS-like tyrosine kinase 3 (FLT3) are present in about 30% of adults with AML and are associated with shorter disease-free and overall survival after initial therapy. Prognosis of relapsed/refractory AML with FLT3 mutations is even more dismal with median overall survival of a few months only. Areas covered: This review will cover current and emerging treatments for relapsed/refractory AML with FLT3 mutations, preclinical rationale and clinical trials with new encouraging data for this particularly challenging population. The authors discuss mechanisms of resistance to FLT3 inhibitors and how these insights serve to identify current and future treatments. As allogeneic stem cell transplant in the first remission is the preferred therapy for newly diagnosed AML patients with FLT3 mutations, the authors discuss the role of maintenance after SCT for the prevention of relapse. Expert opinion: Relapsed/refractory AML with FLT3 mutations remains a therapeutic challenge with currently available treatments. However, the evolution of targeted therapies with next-generation FLT3 inhibitors and their combinations with chemotherapy is showing much promise. Moreover, growing understanding of the pathways of resistance to treatment has led to the identification of various targeted therapies currently being explored, which in time will improve outcomes.

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.