[The clinical and prognostic significance of acute myeloid leukemia with FLT3-ITD]

[Clinical features and prognostic factors in adult acute myeloid leukemia patients with FLT3-ITD and CEBPA gene co-mutation]

Objective: To investigate the clinical characteristics and prognosis in adult acute myeloid leukemia (AML) patients with FLT3-ITD and CEBPA double-mutated (CEBPAdm) co-mutation. Methods: Clinical data and prognostic factors were retrospectively analyzed in adult AML patients with FLT3-ITD and CEBPAdm co-mutation at The First Affiliated Hospital of Zhengzhou University from January 2016 to September 2018. Results: Among 599 non-acute promyelocytic leukemia (APL) patients, 268 received gene mutation detection, who were divided into 4 groups including 19 FLT3-ITD positive (FLT3-ITD(+)) and CEBPAdm positive (CEBPAdm(+)) cases (group A) , 84 FLT3-ITD(+) and CEBPAdm(-) cases (group B) , 95 FLT3-ITD(-) and CEBPAdm(+) cases (group C) , 70 double negative mutation cases (group D) . Gender, platelet count, FAB classification, induction treatment regimen and fusion gene mutation were comparable among four groups (P>0.05) , while age onset, peripheral white blood cell (WBC) count, hemoglobin, percentage of blasts in peripheral blood, percentage of blasts in bone marrow, complete remission rate (CR(1) rate) after the first induction chemotherapy, the relapse rate, the median progression-free survival (PFS) time, and median overall survival (OS) time were significantly different between groups (P<0.05) . When compared in pairs, gender, age onset, hemoglobin, platelet count, FAB classification in group A were not statistically different compared to group B, C and D (P>0.05) , while patients in group A had higher WBC count, blasts in peripheral blood, minimal residual disease (MRD) in bone marrow. The CR(1) rates of group A, B, C, and D were 50.0%、32.4%、59.8%、39.0% respectively (P=0.003) , and the relapse rates were 55.6%, 50.0%, 21.1%, 40.0% (P<0.001) . As to survival, the median OS in each group was 6.25, 3.0, 15.5, 10.5 months respectively (P<0.001) , and the median PFS was 5.0, 4.0, 10.0, 6.7 months (P=0.032) . Conclusion: Adult AML patients with FLT3-ITD and CEBPAdm co-mutation have a higher leukemia load and low CR(1) rate, which translates into poor prognosis with high relapse rate and short survival time.

The FLT3-ITD mutation and the expression of its downstream signaling intermediates STAT5 and Pim-1 are positively correlated with CXCR4 expression in patients with acute myeloid leukemia

Chemokine ligand 12(CXCL12) mediates signaling through chemokine receptor 4(CXCR4), which is essential for the homing and maintenance of Hematopoietic stem cells (HSCs) in the bone marrow. FLT3-ITD mutations enhance cell migration toward CXCL12, providing a drug resistance mechanism underlying the poor effects of FLT3-ITD antagonists. However, the mechanism by which FLT3-ITD mutations regulate the CXCL12/CXCR4 axis remains unclear. We analyzed the relationship between CXCR4 expression and the FLT3-ITD mutation in 466 patients with de novo AML to clarify the effect of FLT3-ITD mutations on CXCR4 expression in patients with AML. Our results indicated a positive correlation between the FLT3-ITD mutant-type allelic ratio (FLT3-ITD MR) and the relative fluorescence intensity (RFI) of CXCR4 expression in patients with AML (r = 0.588, P ≤ 0.0001). Moreover, the levels of phospho(p)-STAT5, Pim-1 and CXCR4 proteins were positively correlated with the FLT3-ITD MR, and the mRNA levels of CXCR4 and Pim-1 which has been revealed as one of the first known target genes of STAT5, were upregulated with an increasing FLT3-ITD MR(P < 0.05). Therefore, FLT3-ITD mutations upregulate the expression of CXCR4 in patients with AML, and the downstream signaling intermediates STAT5 and Pim-1 are also involved in this phenomenon and subsequently contribute to chemotherapy resistance and disease relapse in patients with AML. However, the mechanism must be confirmed in further experiments. The combination of CXCR4 antagonists and FLT3 inhibitors may improve the sensitivity of AML cells to chemotherapy and overcome drug resistance.

[Effect of FLT3-ITD with DNMT3A R882 double-mutation on the prognosis of acute myeloid leukemia after allogeneic hematopoietic stem cell transplantation]

目的

探讨FLT3-ITD和DNMT3A R882双突变对急性髓系白血病（AML）患者allo-HSCT预后的影响。

方法

使用直接测序法检测206例接受allo-HSCT的AML患者（M₃和使用分子靶向药物索拉菲尼的病例除外）初诊时骨髓中常见的基因突变组套（包括FLT3-ITD、DNMT3A、c-kit、CEBPA、FLT3-TKD、NPM1），回顾性分析患者的临床资料，比较各基因突变组的移植预后。

结果

①206例AML患者中男104例，女102例，中位年龄38（3~63）岁。FAB分型：M₀ 6例，M₁ 24例，M₂ 56例，M₄ 39例，M₅ 63例，M₆ 6例，不能分类12例。②全部206例患者根据初诊时的突变基因情况分为4组：FLT3-ITD⁺ DNMT3A R882⁺组（A组）19例，FLT3-ITD⁺ DNMT3A R882⁻组（B组）38例，FLT3-ITD⁻DNMT3A R882⁺组（C组）21例，FLT3-ITD⁻DNMT3A R882⁻组（D组）128例。四组间性别、年龄、初诊时白细胞计数、FAB分型、移植前疾病状态、染色体核型、供者类型、预处理方案及GVHD发生率比较，差异无统计学意义（P>0.05）。③A组和B、C、D组比较，2年累积复发率较高[分别为（72.2±2.6）%、（38.6±0.6）%、（36.8±1.6）%、（27.8±0.1）%，P值均<0.05]，总生存率较低[分别为（30.9±13.3）%、（67.5±7.8）%、（61.4±12.4）%、（80.1±3.7）%，P值均<0.05]，无白血病生存率较低[分别为（11.3±10.2）%、（47.9±8.4）%、（56.8±12.5）%、（79.7±3.6）%，P值均<0.05]。

结论

伴有FLT3-ITD与DNMT3A R882双突变的AML患者移植后累积复发率较高，总生存率和无白血病生存率较差。

[Outcome of acute myeloid leukemia with FLT3-ITD mutation treated by allogeneic hematopoietic stem cell transplantation]

Objective: To evaluate the efficacy of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for the treatment of acute myeloid leukemia (AML) patients with FLT3-ITD mutation. Methods: From September 2008 to December 2016, 40 AML patients with FLT3-ITD mutation were enrolled in the study. The therapeutic process, outcomes and prognostic factors were retrospectively analyzed. Results: The median of WBC at initial diagnosis was 35.0 (range 1.7-185.0) ×10(9)/L. The median course number of chemotherapy was 4 (range 2-7). At the time of transplantation, 34 patients were at the first complete remission (CR(1)) stage, and the other 6 ones were non-remission after chemotherapy. 24 patients received allogeneic transplants from an HLA-matched sibling donor, 7 cases from a HLA-matched unrelated donor, the remaining 9 ones received allograft from a haploidentical donor. The rate of 3-year overall survival (OS) and disease free survival (DFS) in all patients were both 74.3% (95% CI 60.4%-88.2%). The 3-year cumulative incidences of disease relapse and non-relapse mortality were 7.5% (95%CI 1.9%-18.4%) and 18.2% (95% CI 7.9%-32.0%), respectively. More than one course of chemotherapy before achieving CR(1) and the occurrence of acute GVHD after transplantation were associated with poor outcome in terms of OS and DFS. The relapse rates were significantly lower in patients receiving transplantation at CR(1) stage [0 vs 50.0% (95%CI 77.7%-82.9%) , P<0.001] and achieving CR(1) after one course induction therapy [0 vs 16.7% (95%CI 3.9%-37.3%) , P=0.020]. Conclusions: Allo-HSCT was an efficient approach for AML patients with FLT3-ITD mutation. Patients obtained better survival, especially for those achieving CR after one course induction therapy and receiving transplantation at CR(1) stage.