Mutation spectrum of FLT3 and significance of non-canonical FLT3 mutations in haematological malignancy.

Fms-like tyrosine kinase 3 (FLT3) is frequently mutated in haematological malignancies. Although canonical FLT3 mutations including internal tandem duplications (ITDs) and tyrosine kinase domains (TKDs) have been extensively studied, little is known about the clinical significance of non-canonical FLT3 mutations. Here, we first profiled the spectrum of FLT3 mutations in 869 consecutively newly diagnosed acute myeloid leukaemia (AML), myelodysplastic syndrome and acute lymphoblastic leukaemia patients. Our results showed four types of non-canonical FLT3 mutations depending on the affected protein structure: namely non-canonical point mutations (NCPMs) (19.2%), deletion (0.7%), frameshift (0.8%) and ITD outside the juxtamembrane domain (JMD) and TKD1 regions (0.5%). Furthermore, we found that the survival of patients with high-frequency (>1%) FLT3-NCPM in AML was comparable to those with canonical TKD. In vitro studies using seven representative FLT3-deletion or frameshift mutant constructs showed that the deletion mutants of TKD1 and the FLT3-ITD mutant of TKD2 had significantly higher kinase activity than wild-type FLT3, whereas the deletion mutants of JMD had phosphorylation levels comparable with wild-type FLT3. All tested deletion mutations and ITD were sensitive to AC220 and sorafenib. Collectively, these data enrich our understanding of FLT3 non-canonical mutations in haematological malignancies. Our results may also facilitate prognostic stratification and targeted therapy of AML with FLT3 non-canonical mutations.

Flumatinib plus venetoclax as an effective therapy for Philadelphia chromosome-positive acute myeloid leukemia: A case report.

Philadelphia chromosome-positive acute myeloid leukemia (Ph + AML) is a rare type of AML with a low survival rate and poor prognosis. We first report a Ph + AML patient who remained in long-term remission after the combination of flumatinib and venetoclax, which could provide corresponding treatment ideas for clinical practice.

Rapid and Efficient Response to Gilteritinib and Venetoclax-Based Therapy in Two AML Patients with FLT3-ITD Mutation Unresponsive to Venetoclax Plus Azacitidine.

The presence of FLT3-ITD mutation is associated with relapse and poor survival in AML patients. Venetoclax combined with hypomethylating agents (VEN+HMA) was approved for the frontline treatment of elderly or unfit AML patients, which leads to noteworthy impacts on AML management. The combination therapy is associated with encouraging efficacy in FLT3-mutated AML among both newly diagnosed unfit and relapsed/refractory patients. However, we found that two AML patients with FLT3-ITD mutation did not respond to venetoclax plus azacitidine (VEN+AZA). Given that the combined efficacy of venetoclax and the FLT3 inhibitor has been proved in pre-clinical models of FLT3+ AML, it is a scientific rationale to investigate venetoclax combined with the FLT3 inhibitor in AML patients with FLT3-ITD mutation. This is the first report of assessing the safety and response of gilteritinib (the first and only targeted second-generation FLT3 tyrosine kinase inhibitor approved by the US FDA) and venetoclax-based therapy in two AML patients with FLT3-ITD mutation unresponsive to VEN+AZA, which may bring new hope to FLT3 mutated patients who are unresponsive to VEN+HMA.

A Combined Histone Deacetylases Targeting Strategy to Overcome Venetoclax Plus Azacitidine Regimen Resistance in Acute Myeloid Leukaemia: Three Case Reports.

The management of patients with relapsed or refractory (R/R) acute myeloid leukaemia (AML) remains a challenge with few reliably effective treatments. Chidamide, a new selective HDAC inhibitor, has demonstrated some effectiveness in AML patients. Herein, we reported three patients with R/R AML who were unresponsive to venetoclax plus azacitidine (VA) but were successfully treated with VA when chidamide was added to the regimen. MCL1 is one of the anti-apoptotic proteins. Chidamide targets the MCL1 protein, which may permit venetoclax resistance when upregulated. We determined MCL1 protein expression in different AML cell lines, and chidamide could downregulate MCL1 expression in venetoclax resistance AML cells. In general, our experience showed that the chidamide/VA combination could improve the condition of R/R AML patients who are resistant to VA. Formally evaluating this regimen in R/R AML patients may be meaningful.

The influence of maternal islet beta-cell autoantibodies in conjunction with gestational hyperglycemia on neonatal outcomes.

OBJECTIVE: To determine the predictive value of the presence of maternal islet beta-cell autoantibodies with respect to neonatal outcomes. METHODS: A total of 311 pregnant women with abnormal 75 g oral glucose tolerance test (OGTT) results were enrolled in this study. Maternal glutamic acid decarboxylase autoantibodies (GADA), islet cell autoantibodies (ICA) and insulin autoantibodies (IAA) were tested in fasting blood both on the day following the routine OGTT and before delivery. The birth weight, Apgar score, blood glucose and outcomes of each neonate were later evaluated and recorded. RESULTS: 1. In this study, 33.9% of the pregnant women with gestational hyperglycemia had detectable levels of one or more types of anti-islet cell antibodies in the third trimester. The proportion of women who produced GADA and/or ICA was significantly higher in the group of women with gestational hyperglycemia than in the control group (P<0.05). The groups similarly differed in the proportion of women who tested positive for any anti-islet cell antibody (P<0.05). 2. Of the patients in our study, those who produced GADA exhibited an increase in uterine and umbilical arterial pulsatility indexes (PIs) during the third trimesters compared with the control group (P˂0.05). Additionally, an increased frequency of fetal growth restriction (FGR) was observed in the infants of women who produced IAA during pregnancy compared with those without autoantibodies (P˂0.05). 3. The rate of newborn admission to the neonatal intensive care unit (NICU) was significantly associated with the presence of maternal ICA during the third trimester (OR, 6.36; 95% CI, 1.22-33.26). 4. The incidence of neonatal asphyxia was associated with the presence of maternal GADA in both the second (OR, 10.44; 95% CI, 1.46-74.92) and the third (OR, 8.33; 95% CI, 1.45-47.82) trimesters. CONCLUSION: Approximately one-third of the women with gestational hyperglycemia produced anti-islet cell antibodies. The incidence of FGR was higher in women with gestational hyperglycemia who produced IAA than in those without autoantibodies. Maternal ICA production in the third trimester was a risk factor for the subsequent admission of newborns to the NICU. Furthermore, the presence of maternal GADA placed the neonate at increased risk for asphyxia.