Emerging molecular predictive and prognostic factors in acute myeloid leukemia

Evaluating targeted therapies in older patients with TP53-mutated AML

Mutation of thetumor suppressor gene, TP53 (tumor protein 53), occurs in up to 15% of all patients with acute myeloid leukemia (AML) and is enriched within specific clinical subsets, most notably in older adults, and including secondary AML cases arising from preceding myeloproliferative neoplasm (MPN), myelodysplastic syndrome (MDS), patients exposed to prior DNA-damaging, cytotoxic therapies. In all cases, these tumors have remained difficult to effectively treat with conventional therapeutic regimens. Newer approaches fortreatmentofTP53-mutated AML have shifted to interventions that maymodulateTP53 function, target downstream molecular vulnerabilities, target non-p53 dependent molecular pathways, and/or elicit immunogenic responses. This review will describe the basic biology of TP53, the clinical and biological patterns of TP53 within myeloid neoplasms with a focus on elderly AML patients and will summarize newer therapeutic strategies and current clinical trials.

A higher percentage of leukemic blasts with vacuoles predicts unfavorable outcomes in patients with acute myeloid leukemia

Cytoplasmic vacuoles, which are a morphological feature of dysplasia, can be observed under a microscope at initial diagnosis. Recently, this typical morphological feature has been found to be associated with impaired survival. To investigate the clinical significance of the grading of blasts with vacuoles in acute myeloid leukemia (AML), we retrospectively studied 152 patients newly diagnosed with non-M3 AML. The patients were categorized into three groups according to the percentage of blasts with vacuoles (>20 %, 11-20 %, 0-10 %). A high percentage of blasts with vacuoles (>20 %) was positively associated with the European Leukemia Net (2017-ELN) high-risk AML, a complex karyotype, TP53 and IDH1/2 mutations, and CD71 expression and negatively associated with the ELN low-risk category. Importantly, patients who had a higher percentage of blasts with vacuoles had a lower complete remission rate in response to first-cycle induction chemotherapy. The overall survival and event-free survival of patients who had a higher percentage of blasts with vacuoles were significantly shorter. Moreover, multivariate analysis showed that blast vacuolization was an independent high prognostic factor for AML. In conclusion, a higher percentage of leukemic blasts with vacuoles predicts worse outcomes in AML and may have potential as a prognostic marker.

Novel insights of acute myeloid leukemia with CEBPA deregulation: Heterogeneity dissection and re-stratification

Acute myeloid leukemia with bi-allelic CEBPA mutation was categorized as an independent disease entity with favorable prognosis, however, recent researches have revealed huge heterogeneity within this disease group, and for some patients, relapse remained a major cause of treatment failure. Further risk stratification is essentially needed. Here by reviewing the latest literature, we summarized the characteristics of CEBPA mutation profiles and clinical features, with a special intention of dissecting the heterogeneity within the seemingly homogeneous AML with bi-allelic CEBPA mutations. Specifically, non-classical CEBPA mutation, miscellaneous companion genetic aberrations and the presence of germline CEBPA mutation are three major sources of heterogeneity. Identifying these factors can help us predict patients at a higher risk of relapse, for whom aggressive treatment may be recommended. Novel therapeutic approaches regarding manipulating potentially druggable targets as well as the debate over post remission consolidation regimens has also been discussed.

Genome-wide CRISPR screen identifies regulators of MAPK and MTOR pathways mediating sorafenib resistance in acute myeloid leukemia

Drug resistance impedes the long-term effect of targeted therapies in acute myeloid leukemia (AML), necessitating the identification of mechanisms underlying resistance. Approximately 25% of AML patients carry FLT3 mutations and develop post-treatment insensitivity to FLT3 inhibitors, including sorafenib. Using a genomewide CRISPR screen, we identified LZTR1, NF1, TSC1 and TSC2, negative regulators of the MAPK and MTOR pathways, as mediators of resistance to sorafenib. Analyses of ex vivo drug sensitivity assays in samples from patients with FLT3-ITD AML revealed that lower expression of LZTR1, NF1, and TSC2 correlated with sensitivity to sorafenib. Importantly, MAPK and/or MTOR complex 1 (MTORC1) activity was upregulated in AML cells made resistant to several FLT3 inhibitors, including crenolanib, quizartinib, and sorafenib. These cells were sensitive to MEK inhibitors, and the combination of FLT3 and MEK inhibitors showed enhanced efficacy, suggesting the effectiveness of such treatment in AML patients with FLT3 mutations and those with resistance to FLT3 inhibitors.

Clinical efficacy of decitabine in combination with standard-dose cytarabine, aclarubicin hydrochloride, and granulocyte colony-stimulating factor in the treatment of young patients with newly diagnosed acute myeloid leukemia

Purpose: The chemotherapeutic regimen DCAG (decitabine with cytarabine, aclarubicin hydrochloride, and granulocyte colony-stimulating factor) is effective for elderly patients with acute myeloid leukemia, but recommendations for young patients remain controversial. This study investigated the tolerance and efficacy of DCAG for patients with newly diagnosed acute myeloid leukemia (aged 14–60 years). The clinical features or molecular markers that may predict response to DCAG were identified.

Patients and methods: One-hundred sixty-one consecutive patients with newly diagnosed acute myelogenous leukemia received DCAG or standard (idarubicin plus cytarabine, IA) induction chemotherapy (n=64 and 97, respectively).

Results: The rates of complete remission after the first cycle, overall survival (OS), and event-free survival (EFS) were comparable. After the second cycle, the complete remission rate of the DCAG group (54.7%) was significantly lower than that of the reference (78.35%, P=0.005). The following were associated with significantly worse OS, and EFS, in the DCAG group: Eastern Cooperative Oncology Group (ECOG) score ≥3 and no response after the second induction therapy; and FLT3-ITD. The multivariate analysis showed the DCAG group with significantly shorter OS associated with ECOG ≥3 and FLT3-ITD. In the DCAG group, after the first cycle of induction chemotherapy the median recovery times of neutrophils and platelets were 15.8 and 13 days.

Conclusion: The DCAG and IA groups were similar with regard to complete remission rate after the first cycle, OS, and EFS. The complete remission rate after the second cycle of the DCAG was significantly lower than that of the IA. Grade 4 neutropenia and thrombocytopenia were a major adverse event associated with DCAG.

Chronic myelomonocytic leukemia associated with myeloid sarcomas and NPM1 mutation: a case report and literature review

We present a case of chronic myelomonocytic leukemia (CMML) associated with myeloid sarcomas. The CMML also harbored a NPM1 mutation, which is uncommonly described outside the context of acute myeloid leukemia (AML). We describe our treatment strategy, which involved remission-induction chemotherapy that led to rapid resolution of myeloid sarcomas, and we present a literature review highlighting the treatment challenges that similar cases pose.

Sorafenib Dose Recommendation in Acute Myeloid Leukemia Based on Exposure-FLT3 Relationship

Sorafenib administered at the approved dose continuously is not tolerated long-term in patients with acute myeloid leukemia (AML). The purpose of this study was to optimize the dosing regimen by characterizing the sorafenib exposure-response relationship in patients with AML. A one-compartment model with a transit absorption compartment and enterohepatic recirculation described the exposure. The relationship between sorafenib exposure and target modulation of kinase targets (FMS-like tyrosine kinase 3 (FLT3)-ITD and extracellular signal-regulated kinase (ERK)) were described by an inhibitory maximum effect (Emax ) model. Sorafenib could inhibit FLT3-ITD activity by 100% with an IC50 of 69.3 ng/mL and ERK activity by 84% with an IC50 of 85.7 ng/mL (both adjusted for metabolite potency). Different dosing regimens utilizing 200 or 400 mg at varying frequencies were simulated based on the exposure-response relationship. Simulations demonstrate that a 200 mg twice daily (b.i.d.) dosing regimen showed similar FLT3-ITD and ERK inhibitory activity compared with 400 mg b.i.d. and is recommended in further clinical trials in patients with AML.