FLT3-ITD positive acute myeloid leukemia: A retrospective analysis of the role of allogeneic transplant and allelic ratio in patient management

Outcomes of pediatric acute myeloid leukemia patients with FLT3-ITD mutations in the pre-FLT3 inhibitor era

Background

Acute myeloid leukemia (AML) with internal tandem duplication in FMS-like tyrosine kinase 3 (FLT3-ITD) is associated with poor outcomes. This study aimed to analyze the outcomes of pediatric AML patients with FLT3-ITD mutations in the pre-FLT3 inhibitor era.

Methods

We retrospectively reviewed and identified 18 patients diagnosed with non-M3 AML with FLT3-ITD mutations at Seoul National University Children’s Hospital between May 2008 and August 2019.

Results

The median age was 13 years (range, 6‒19 yr). The median follow-up time was 43 months (range, 6‒157 mo). Fourteen patients received BH-AC-based (N4-Behenoy1-1-b-D-arabinofuranosy1cytosine) and 4 received cytarabine-based induction chemotherapy. Complete remission (CR) was achieved in 72.2% of the patients after the first induction chemotherapy and 80% of the patients achieved CR after salvage therapy. The overall CR rate was 94% (17/18 patients). These 17 patients underwent hematopoietic stem cell transplantation (9 matched unrelated donors, 5 matched related donors, and 3 haploidentical donors). Relapse occurred in 22% of the patients. Event free survival and overall survival rates were 53.8±12.1% and 53.6±12.1%, respectively, and they were not significantly different according to the type of induction chemotherapy (P=0.690) or the type of donor (P=0.102).

Conclusion

This study outlines the outcomes of pediatric AML patients with FLT3-ITD-mutations in one institution over a decade. Outcomes were significantly improved in this study compared to our previous report in 2004, where RFS and EFS were 0%. This study can provide baseline data for pediatric patients in the pre-FLT3 inhibitor era.

Midostaurin in combination with chemotherapy is most effective in patients with acute myeloid leukemia presenting with high FLT3-ITD allelic ratio who proceed to allogeneic stem cell transplantation while in first complete remission

OBJECTIVES

Midostaurin, a multikinase and FLT3 inhibitor, is the first non-chemotherapy agent approved and widely adopted for the treatment of FLT3-ITD acute myeloid leukemia (AML). Yet, its role in improving survival of patients referred to allogeneic stem cell transplantation (allo-SCT) in first complete remission (CR1) needs to be defined.

METHODS

This multicenter study retrospectively evaluated the outcome of 119 FLT3-ITD AML patients [59 (49.6%) males and 60 females] intensively treated between 2015 and 2019 at five Israeli centers. In our cohort, allo-SCT in CR1 was widely implemented (47%) and patient stratification was based on the current allelic ratio (AR) cutoff of 0.5.

RESULTS

Ninety-eight patients (82.3%) achieved CR1/CR with incomplete count recovery (CRi). Death during induction was reported in 7 (5.9%) patients. In multivariate analysis, midostaurin use and allo-SCT in CR1 were the most significant factors affecting overall survival (OS). Midostaurin incorporation in chemotherapy regimens significantly improved CR + CRi rates (P = .002), reduced relapse rates (P = .02), and was remarkably advantageous for high-AR patients (2-year OS 82%). In low-AR patients, the midostaurin effect was much less prominent.

CONCLUSIONS

Our results demonstrate benefits of midostaurin incorporation in intensive chemotherapy regimens, particularly for high-AR AML patients to whom it should be offered along with allo-SCT in CR1.

Combination of FLT3-ITD Allelic Ratio, NPM1 Mutation, and Immunophenotypic Markers to Modulate Outcome Prediction in Patients with Normal Karyotype Acute Myelogenous Leukemia Undergoing Hematopoietic Stem Cell Transplantation

NPM1 mutation status and the allelic ratio (AR) of FLT3-internal tandem duplication (FLT3-ITD) are routinely tested for disease risk stratification in patients with normal karyotype (NK) acute myelogenous leukemia (AML); however, the predictive impact of immunophenotypic markers on different NPM1/FLT3 genotypes remains unclear. We performed a retrospective analysis of 423 patients with NK-AML subclassified into groups based on NPM1/FLT3 genotype. Allogeneic hematopoietic stem cell transplantation (HSCT) was performed in 124 of 423 patients (29%) and was significantly associated with longer event-free survival (EFS) and overall survival (OS), except for patients with the favorable genotype, defined as mutated NPM1 (NPM1^mut) combined with normal FLT3 status (FLT3-ITD^neg) or FLT3-ITD AR <.5 (FLT3-ITD^low). A subset of AML patients bearing the favorable NPM1^mut/FLT3-ITD^neg/low genotype share similar outcomes with AML patients who have the intermediate FLT3/NPM1 genotype defined by normal NPM1 (NPM1^wt) and FLT3-ITD^neg/low. In these individuals, the lack of CD13 expression (CD13^neg) was associated with shorter EFS (P = .041) and OS (P = .017). CD13^neg was an independent predictor for shorter OS (hazard ratio, 1.985; P = .028).

Identification of long non-coding RNA competing interactions and biological pathways associated with prognosis in pediatric and adolescent cytogenetically normal acute myeloid leukemia

Background

LncRNAs can regulate miRNAs and mRNAs by sequestering and binding them. Indeed, many researchers have reported lncRNA mediated-competing endogenous RNAs (ceRNAs) could regulate the progression of solid tumors. However, the roles of ceRNA in acute myeloid leukemia (AML), especially in pediatric and adolescent AML, were not completely expounded.

Materials and methods

27 cytogenetically normal acute myeloid leukemia (CN-AML) patients under 18 years old with corresponding clinical data were selected from the cancer genome atlas (TCGA), which was a large sample sequencing database of RNA sequencing. We constructed a survival specific ceRNA network, and investigated its associations with patients' clinical information by analyzing the data from TCGA.

Results

We identified survival specific lncRNAs, miRNAs and mRNAs, and constructed a survival specific ceRNA network of CN-AML patients and a weighted correlation network. Furthermore, we identified 4 biological pathways associated with OS and selected the most enriched pathway 'Transcriptional misregulation in cancer' to verify that it could accurately predict younger CN-AML patients' prognosis to guide treatment.

Conclusions

We successfully constructed a survival specific ceRNA network which could provide a new approach to lncRNA research in younger CN-AML. Importantly, we constructed a weighted correlation network to overcome the difficulty in biological interpretation of individual genes.