FLT3 internal tandem duplication does not impact prognosis after haploidentical allogeneic hematopoietic stem cell transplantation in AML patients

The latest edition of WHO and ELN guidance and a new risk model for Chinese acute myeloid leukemia patients

Objective

Diagnosis classification and risk stratification are crucial in the prognosis prediction and treatment selection of acute myeloid leukemia (AML). Here, we used a database of 536 AML patients to compare the 4th and 5th WHO classifications and the 2017 and 2022 versions of ELN guidance.

Methods

AML patients were classified according to the 4th and 5th WHO classifications, as well as the 2017 and 2022 versions of the European LeukemiaNet (ELN) guidance. Kaplan-Meier curves with log-rank tests were used for survival analysis.

Results

The biggest change was that 25 (5.2%), 8 (1.6%), and 1 (0.2%) patients in the AML, not otherwise specified (NOS) group according to the 4th WHO classification, were re-classified into the AML-MR (myelodysplasia-related), KMT2A rearrangement, and NUP98 rearrangement subgroups based on the 5th WHO classification. Referring to the ELN guidance, 16 patients in the favorable group, six patients in the adverse group, and 13 patients in the intermediate group based on the 2017 ELN guidance were re-classified to the intermediate and adverse groups based on the 2022 ELN guidance. Regrettably, the Kaplan-Meier curves showed that the survival of intermediate and adverse groups could not be distinguished well according to either the 2017 or 2022 ELN guidance. To this end, we constructed a risk model for Chinese AML patients, in which the clinical information (age and gender), gene mutations (NPM1, RUNX1, SH2B3, and TP53), and fusions (CBFB::MYH11 and RUNX1::RUNX1T1) were included, and our model could help divide the patients into favorable, intermediate, and adverse groups.

Conclusion

These results affirmed the clinical value of both WHO and ELN, but a more suitable prognosis model should be established in Chinese cohorts, such as the models we proposed.

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.

Adverse impact of a high allelic burden FLT3-ITD mutation on allogeneic hematopoietic stem cell transplantation in patients with cytogenetically normal AML

Risks associated with the FLT3-ITD mutation in patients receiving chemotherapy alone for cytogenetic normal acute myeloid leukemia (CN-AML) depend on the allelic ratio (AR) and concomitant NPM1 mutation. Nevertheless, their prognostic ability after allogeneic hematopoietic cell transplantation (allo-HCT) remains undetermined. Moreover, previous studies have revealed that haploidentical transplantation improves outcomes of FLT3-ITD patients. To elucidate whether this alteration also impacts prognosis of myeloablative allo-HCT upon first remission, we retrospectively reviewed the prognostic ability of FLT3-ITD mutations in 205 CN-AML patients. Our analysis demonstrated that FLT3-ITD AR was closely related to pretransplant MRD and induction response. Multivariate analysis showed that high-AR FLT3-ITD, pretransplant MRD and induction response were independent risk factors for CN-AML. In addition, we presented evidence that the high-AR FLT3-ITD patient prognosis was not overcome by haploidentical transplantation, but was markedly improved by cGVHD. More importantly, among patients with negative pretransplant MRD, high-AR FLT3-ITD patients did not have increased relapse risk, compared to low-AR FLT3-ITD and wild-type FLT3 patients. Our findings will aid in accurate prognostic stratification of FLT3-ITD patients. We also recommend further targeted and coordinated approaches to sustain durable remission following induction chemotherapy and allo-HCT in this high-risk patient population.

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.

Effects of second transplantation with T-cell-replete haploidentical graft using low-dose anti-thymocyte globulin on long-term overall survival in pediatric patients with relapse of leukemia after first allogeneic transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the preferred treatment for children with high-risk hematologic malignancies, but post-allo-HSCT relapse has a poor prognosis and limited treatment options. We evaluated the feasibility, outcome, and risk factors influencing survival after T-cell-replete haploidentical HSCT with low-dose anti-thymocyte globulin (ATG) in 30 patients with post-allo-HSCT relapse of acute lymphoblastic leukemia and acute myeloid leukemia. Overall, 50% of the patients had complete remission (CR) before the second transplant and the overall survival (OS) rate was 52%. In surviving patients (median follow-up 614 days), Kaplan-Meier analysis revealed estimated 2-year leukemia-free survival and OS rates of 48.1% and 61.1%, respectively. Cumulative incidences of 2-year non-relapse mortality and relapse were 24.7% and 36.3%, respectively. Achieving CR before the second allo-HSCT was a predominant independent prognostic factor identified in the multivariate analysis, with a significantly improved 2-year OS rate of 86.7%. T-cell-replete haplo-HSCT with low-dose ATG for second allo-HSCT may benefit a selected patient population.

Allogeneic hematopoietic stem cell transplantation from a 2-HLA-haplotype-mismatched family donor for posttransplant relapse: a prospective phase I/II study

HLA haploidentical hematopoietic stem cell transplantation (HSCT), i.e., HSCT from a 1-HLA-haplotype-mismatched family donor, has been successfully performed even as a second transplantation for posttransplant relapse. Is the haploidentical the limit of HLA mismatches in HSCT? In order to explore the possibility of HLA-mismatched HSCT from family donors beyond haploidentical relatives, we conducted a prospective phase I/II study of 2-HLA-haplotype-mismatched HSCT (2-haplo-mismatch HSCT). We enrolled 30 patients with posttransplant relapse (acute myeloid leukemia: 18, acute lymphoblastic leukemia: 11, non-Hodgkin lymphoma: 1). 2-haplo-mismatch HSCT was performed as the second to sixth transplantations. The donors were siblings (n = 12), cousins (n = 16), and second cousins (n = 2). The conditioning regimen consisted of fludarabine, cytarabine, melphalan, low-dose anti-thymocyte globulin, and 3 Gy of total body irradiation. Graft-versus-host disease (GVHD) prophylaxis consisted of tacrolimus, methylprednisolone, and mycophenolate mofetil. All patients achieved neutrophil engraftment, except for a case of early death. The cumulative incidences of grades II-IV and III-IV acute GVHD were 36.7% and 16.7%, respectively. The overall survival at 1 year, relapse, and non-relapse mortality rates was 30.1%, 38.9%, and 44.3%, respectively. Considering the poor prognosis of posttransplant relapse, 2-haplo-mismatch HSCT can be an alternative option in a second or third transplantation.

Clinical practice recommendation on hematopoietic stem cell transplantation for acute myeloid leukemia patients with FLT3-internal tandem duplication: a position statement from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

The FMS-like tyrosine kinase 3 (FLT3) gene is mutated in 25-30% of patients with acute myeloid leukemia (AML). Because of the poor prognosis associated with FLT3-internal tandem duplication mutated AML, allogeneic hematopoietic stem-cell transplantation (SCT) was commonly performed in first complete remission. Remarkable progress has been made in frontline treatments with the incorporation of FLT3 inhibitors and the development of highly sensitive minimal/measurable residual disease assays. Similarly, recent progress in allogeneic hematopoietic SCT includes improvement of transplant techniques, the use of haploidentical donors in patients lacking an HLA matched donor, and the introduction of FLT3 inhibitors as post-transplant maintenance therapy. Nevertheless, current transplant strategies vary between centers and differ in terms of transplant indications based on the internal tandem duplication allelic ratio and concomitant nucleophos-min-1 mutation, as well as in terms of post-transplant maintenance/consolidation. This review generated by international leukemia or transplant experts, mostly from the European Society for Blood and Marrow Transplantation, attempts to develop a position statement on best approaches for allogeneic hematopoietic SCT for AML with FLT3-internal tandem duplication including indications for and modalities of such transplants and on the potential optimization of post-transplant maintenance with FLT inhibitors.

Leukemia relapse following unmanipulated haploidentical transplantation: a risk factor analysis on behalf of the ALWP of the EBMT

BACKGROUND

As information on incidence, risk factors, and outcome of acute leukemia (AL) relapse after unmanipulated haploidentical stem cell transplantation (haplo-SCT) is scarce, a retrospective registry study was performed by the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation.

METHODS

Among 1652 transplants performed for lymphoblastic and myeloid AL between 2007 and 2014, 587 patients (acute lymphoblastic leukemia (ALL) 131, acute myeloid leukemia (AML) 456) with detailed information were analyzed aiming to identify risk factors for post-transplant relapse and for overall survival (OS) after relapse.

RESULTS

The cumulative incidence of relapse at 3 years was 44% (35-53%) for ALL and 32% (27-36%) for AML (p = 0.023). In ALL, risk factors for relapse were disease status different from the first complete remission (CR1) at haplo-SCT (CR2 vs CR1: HR 2.85, p = 0.011; advanced vs CR1: HR 14.28, p < 0.0001) and male donor gender (HR 3.64, p = 0.0002), while in AML, risk factors were advanced disease at haplo-SCT (advanced vs CR1: HR 3.95, p < 0.0001) and comorbidities (HCT-CI) ≥ 3 (HR 1.75, p = 0.014). Transplants performed in more recent years were associated with lower relapse incidence (RI) in AML, but not in ALL (HR 0.91, p = 0.042). After relapse, median follow-up was 13 months (mos). OS at 1-year post relapse was 18%. Prognostic factors for superior OS after relapse were remission at time of haplo-SCT (CR vs advanced: HR 0.71, p = 0.028), time from transplant to relapse (≥ 5 mos vs < 5 mos: HR 0.530, p < 0.0001), and bone marrow as a stem cell source (peripheral blood (PB) vs bone marrow (BM): HR 1.473, p = 0.016).

CONCLUSIONS

Risk factors for relapse after haploidentical transplantation were disease specific. Longer OS after relapse was achieved in particular by patients both in CR at haplo-SCT and relapsing more than 5 months after transplant (1-year OS 33%).