Actualización de resultados demográficos y terapéuticos de pacientes con Leucemia Mieloide Aguda no promielocítica en el Hospital Clínico de la Pontificia Universidad Católica de Chile / Acute myeloid leukemia. Analysis of 114 patients

BACKGROUND: Acute myeloid leukemia (AML) is the most common leukemia in adults. Aim: To Describe our population of patients with AML and report the outcomes of our treatments. MATERIAL AND METHODS: Review of electronic clinical records of 114 patients with AML with a median age of 57 years (59% men). Results: Seventeen percent of patients were classified as low risk, 38% as intermediate risk and 33% as high risk. Seventy-six percent of patients were treated with intensive chemotherapy. Five years overall survival according to cytogenetic risk was 59, 41, and 12% in low, intermediate, and high-risk patients, respectively. The outcomes were better in patients under 60 years. The median survival of patients treated with intensive chemotherapy aged less than 60 years and 60 years and above was 3.4 and 1 year, respectively. CONCLUSIONS: Our results are comparable to those reported in developed countries. Improving the survival of patients 60 years and older is our main challenge.

Unusual Karyotype in Acute Myelomonocitic Leukemia: A Case Report.

BACKGROUND/AIM: Acute myeloid leukemia is well characterized by chromosomal aberrations that correspond to various subtypes of acute leukemias. The t(8;21)(q22;q22) is a frequent chromosomal abnormality strongly associated with acute myeloblastic leukemia with maturation (AML-M2), but is rarely associated with other subtypes. Translocation involving a third chromosome could produce new genetic rearrangements that lead to leukemogenesis. PATIENTS AND METHODS: Conventional cytogenetic analysis and fluorescence in situ hybridization (FISH) were performed to identify the karyotype. Reverse transcriptase polymerase chain reaction (RT-PCR) was used to detect the AML1/ETO transcript. RESULTS/CONCLUSION: We herein report a novel rearrangement with a three-way translocation involving chromosomes 8, 21 and another unknown chromosome, in an 83-year-old female patient diagnosed as AML-M4, with an ALM1/ETO negative transcript. This is an uncommon case of AML-M4 with three-way translocation in a new variant of t(8;21) acute myeloid leukaemia. The detailed mechanism of different phenotype expression is unclear. Further study is needed to identify the leukemogenetic transformation resulting from t(8;21) translocation.

[Sorafenib - induced thyroiditis in patient with a relapse of acute myelomonocytic leukemia with FLT3-ITD mutation].

Sorafenib has been used in acute myeloid leukemias with FLT3-ITD mutation improving the outcomes. However the high incidence of treatment - emergent adverse event may be associated with treatment using sorafenib with cytotoxic chemotherapy. We have reported a case of severe thyroiditis in patient with a relapse of acute myelomonocytic leukemia.

Acute myeloid/T-lymphoblastic leukaemia (AMTL): a distinct category of acute leukaemias with common pathogenesis in need of improved therapy.

Advances in the classification of acute leukaemias have led to improved outcomes for a substantial fraction of patients. However, chemotherapy resistance remains a major problem for specific subsets of acute leukaemias. Here, we propose that a molecularly distinct subtype of acute leukaemia with shared myeloid and T cell lymphoblastic features, which we term acute myeloid/T-lymphoblastic leukaemia (AMTL), is divided across 3 diagnostic categories owing to variable expression of markers deemed to be defining of myeloid and T-lymphoid lineages, such as myeloperoxidase and CD3. This proposed diagnostic group is supported by (i) retained myeloid differentiation potential during early T cell lymphoid development, (ii) recognition that some cases of acute myeloid leukaemia (AML) harbour hallmarks of T cell development, such as T-cell receptor gene rearrangements and (iii) common gene mutations in subsets of AML and T cell acute lymphoblastic leukaemia (T-ALL), including WT1, PHF6, RUNX1 and BCL11B. This proposed diagnostic entity overlaps with early T cell precursor (ETP) T-ALL and T cell/myeloid mixed phenotype acute leukaemias (MPALs), and also includes a subset of leukaemias currently classified as AML with features of T-lymphoblastic development. The proposed classification of AMTL as a distinct entity would enable more precise prospective diagnosis and permit the development of improved therapies for patients whose treatment is inadequate with current approaches.

Enhancement of chemosensitivity by simultaneously silencing of Mcl-1 and Survivin genes using small interfering RNA in human myelomonocytic leukaemia.

Acute myeloid leukaemia (AML) is a genetically heterogeneous, severe and rapidly progressing disease triggered by blocking granulocyte or monocyte differentiation and maturation. Overexpression of myeloid cell leukaemia-1 (Mcl-1) and Survivin is associated with drug resistance, tumour progression and inhibition of apoptotic mechanisms in leukaemia and several cancers. In the present study, we examined the combined effect of etoposide and dual siRNA-mediated silencing of Mcl-1 and Survivin on U-937 AML cells. The AML cells were co-transfected with Mcl-1 and Survivin-specific siRNAs and genes silencing were confirmed by quantitative real-time PCR and Western blotting. Subsequently, MTT assay was used for the evaluation of cytotoxic effects by dual siRNA and etoposide on their own and in combination. For the studying of apoptosis, DNA-histone ELISA and annexin-V/FITC assays were performed. Co-transfection of Mcl-1 and Survivin siRNA significantly blocked their expression at the mRNA and protein levels, leading to the induction of apoptosis and strong inhibition of growth (p < .05). Besides, combined treatment of etoposide with Mcl-1 and Survivin siRNAs co-transfection leads to synergistically enhance etoposide-induced cytotoxic and apoptotic effects (p < .05). The results showed that Mcl-1 and Survivin play a major role in the U937 cells survival and their resistance relative to etoposide. Thus, Mcl-1 and Survivin can be considered as promising molecular targets for the treatment of AML. The combination treatment with etoposide, and siRNA-mediated silencing of corresponding genes may be a novel strategy in chemoresistance AML treatment.

Recurrent somatic JAK-STAT pathway variants within a RUNX1-mutated pedigree.

Germline variants within the transcription factor RUNX1 are associated with familial platelet disorder and acute leukemia in over 40% of carriers. At present, the somatic events triggering leukemic transformation appear heterogeneous and profiles of leukemia initiation across family members are poorly defined. We report a new RUNX1 family where three sisters harboring a germline nonsense RUNX1 variant, c.601C>T (p.(Arg201*)), developed acute myelomonocytic leukemia (AML) at 5 years of age. Whole-exome sequencing of tumor samples revealed all three siblings independently acquired variants within the JAK-STAT pathway, specifically targeting JAK2 and SH2B3 (a negative regulator of JAK2), while also sharing the 46/1 haplotype linked with sporadic JAK2-positive myeloproliferative neoplasms. In-depth chromosomal characterization of tumors revealed acquired copy number gains and uniparental disomy amplifying RUNX1, JAK2 and SH2B3 variants, highlighting the significance of co-operation between these disrupted pathways. One sibling, presenting with myelodysplasia at 14 years, had no evidence of clonal or subclonal JAK2 or SH2B3 variants, suggesting the latter were specifically associated with leukemic transformation in her sisters. Collectively, the clinical and molecular homogeneity across these three young siblings provides the first notable example of convergent AML evolution in a RUNX1 pedigree, with the recurrent acquisition of JAK-STAT pathway variants giving rise to high-risk AML, characterized by chemotherapy resistance and relapse.

Cooperation of MLL/AF10(OM-LZ) with PTPN11 activating mutation induced monocytic leukemia with a shorter latency in a mouse bone marrow transplantation model.

PTPN11 mutation, a RAS signaling pathway mutation, is associated with MLL translocations in acute leukemia. A girl with MLL/AF10 AML was found to carry PTPN11G503A . To study the impact of PTPN11G503A cooperating with MLL/AF10 on leukemogenesis, we established a retroviral transduction/transplantation mouse model. Compared to the MLL/AF10(OM-LZ) leukemia cells harboring PTPN11wt , the cells harboring PTPN11G503A were hypersensitive to GM-CSF and IL3, and more resistant to death upon treatment with daunorubicin but sensitive to cytarabine. The cells harboring PTPN11G503A autonomously differentiated into macrophages (1.8%) in the medium containing IL3. Further studies showed that the cells had an elevated (∼2.9-fold) Csf1 transcription level and secreted more (∼4.5-fold) M-CSF to the medium which can stimulate monocyte/macrophage differentiation of BM cells. Mice transplanted with the cells harboring PTPN11G503A had a higher concentration of M-CSF in plasma. When mixed with the MLL/AF10(OM-LZ) leukemia cells harboring PTPN11wt , the cells harboring PTPN11G503A had an increased competitive engraftment and clonal expansion in the BM and spleen of recipient mice, although no competitive growth advantage was observed in the in vitro co-culturing assays. The mice transplanted with the MLL/AF10(OM-LZ) cells harboring PTPN11wt developed myelomonocytic leukemia, while those transplanted with the cells harboring PTPN11G503A -induced monocytic leukemia in a shorter latency. Our results demonstrated that addition of PTPN11G503A to MLL/AF10 affected cell proliferation, chemo-resistance, differentiation, in vivo BM recruitment/clonal expansion and accelerated disease progression.

The prognostic implication of SRSF2 mutations in Chinese patients with acute myeloid leukemia.

Recently, somatic mutations in SRSF2 gene have been discovered in a proportion of hematologic malignancies including acute myeloid leukemia (AML). This study was aimed to investigate SRSF2 mutations in Chinese AML patients. High-resolution melting analysis (HRMA) was developed to screen SRSF2 mutations in 249 cases with AML, and then direct DNA sequencing was used to verify the results of HRMA. In this study, 3.6 % (9/249) of Chinese AML patients were found with heterozygous SRSF2 mutations. Patients with SRSF2 mutations were older than those with wild-type SRSF2 (P = 0.014). No differences in the sex, blood parameters, French-American-British classification (FAB) subtypes, and karyotypes were observed between AML patients with and without SRSF2 mutations. Although the overall survival (OS) of SRSF2-mutated patients was inferior to those without mutations in both whole AML patients (median 4 vs. 11 months, respectively; P = 0.006) and cytogenetically normal patients (median 2 vs. 12 months, respectively; P = 0.008), multiple analysis disclosed that SRSF2 mutation was not an independent prognostic factor in AML patients. These results suggest that SRSF2 mutation occurs at a low frequency in aged AML patients and might not be associated with adverse prognosis in Chinese AML patients.

Identification of a Cryptic Insertion ins(11;X)(q23;q28q12) Resulting in a KMT2A-FLNA Fusion in a 13-Month-Old Child with Acute Myelomonocytic Leukemia.

In pediatric acute myeloid leukemia (AML), chromosomal abnormalities leading to a disruption of the lysine methyltransferase 2A (KMT2A) gene in 11q23 are the most frequent rearrangements. Here, we report on the identification of a novel cryptic insertion, ins(11;X)(q23;q28q12), resulting in a translocation of the KMT2A gene in 11q23, leading to a KMT2A-FLNA fusion in a 13-month-old boy with de novo acute myelomonocytic leukemia, who died 38 days after diagnosis. The patient presented a complex karyotype 48∼49,Y,del(X)(q12),+del(X)(q12),+8,ins(11;X)(q23; q28q12),+19. The identified fusion gene was predicted to be out-of-frame (fusion of portions of KMT2A exon 11 with FLNA exon 11). However, RT-PCR experiments demonstrated that a potentially functional transcript was generated by alternative splicing where KMT2A exon 10 was spliced in-frame to the truncated FLNA exon 11. This case report helps to better understand the rare but potentially severe impact of KMT2A- FLNA fusions in infants with AML to improve prognostic stratification of therapy and clinical management.

The oncofusion protein FUS-ERG targets key hematopoietic regulators and modulates the all-trans retinoic acid signaling pathway in t(16;21) acute myeloid leukemia.

The ETS transcription factor ERG has been implicated as a major regulator of both normal and aberrant hematopoiesis. In acute myeloid leukemias harboring t(16;21), ERG function is deregulated due to a fusion with FUS/TLS resulting in the expression of a FUS-ERG oncofusion protein. How this oncofusion protein deregulates the normal ERG transcription program is unclear. Here, we show that FUS-ERG acts in the context of a heptad of proteins (ERG, FLI1, GATA2, LYL1, LMO2, RUNX1 and TAL1) central to proper expression of genes involved in maintaining a stem cell hematopoietic phenotype. Moreover, in t(16;21) FUS-ERG co-occupies genomic regions bound by the nuclear receptor heterodimer RXR:RARA inhibiting target gene expression and interfering with hematopoietic differentiation. All-trans retinoic acid treatment of t(16;21) cells as well as FUS-ERG knockdown alleviate the myeloid-differentiation block. Together, the results suggest that FUS-ERG acts as a transcriptional repressor of the retinoic acid signaling pathway.