Current treatment for pediatric acute myeloid leukemia

Construction of a target MSNs drugcarrier loaded with siRNAGLI1 and siRNASMO aim at hedgehog signal pathway and the pharmacodynamic study of drug-carriers in the treatment of leukemia stem cells

Leukemia stem cells (LSCs) are responsible for leukemia initiation and targeting LSCs is one strategy to treat this disease. This study aims to target LSCs using multi-siRNA loaded antibodies modified with mesoporous silica nanoparticles (MSNs). Here, both siRNA_GLI1 and siRNA_SMO were loaded in an anti-CD34 antibody modified with MSNs, and then, the MSN@siRNA_GLI1@Antibody + MSNs@siRNA_SMO@Antibody cocktail was used to target LSCs. Expression levels of BCL-2 in LSCs were significantly reduced whereas Bax expression was significantly increased after treatment with nano-drug carriers. In addition, these nano-drug carriers also effectively induced the apoptosis of LSCs. The MSNs@siRNA_GLI1@Antibody + MSNs@siRNA_SMO@Antibody cocktail significantly inhibited LSCs. In short, we constructed two target MSN nano-drug carriers where loaded siRNAs can be used in a chemotherapeutic drug cocktail to improve the treatment of leukemia.

HDAC8 promotes daunorubicin resistance of human acute myeloid leukemia cells via regulation of IL-6 and IL-8

The chemoresistance is one of the major challenges for acute myeloid leukemia (AML) treatment. We found that the expression of histone deacetylase 8 (HDAC8) was increased in daunorubicin (DNR) resistant AML cells, while targeted inhibition of HDAC8 by its specific siRNA or inhibitor can restore sensitivity of DNR treatment . Further, targeted inhibition of HDAC8 can suppress expression of interleukin 6 (IL-6) and IL-8. While recombinant IL-6 (rIL-6) and rIL-8 can reverse si-HDAC8-resored DNR sensitivity of AML cells. Mechanistical study revealed that HDAC8 increased the expression of p65, one of key components of NF-κB complex, to promote the expression of IL-6 and IL-8. It might be due to that HDAC8 can directly bind with the promoter of p65 to increase its transcription and expression. Collectively, our data suggested that HDAC8 promotes DNR resistance of human AML cells via regulation of IL-6 and IL-8.

High-throughput drug screening reveals Pyrvinium pamoate as effective candidate against pediatric MLL-rearranged acute myeloid leukemia

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Drug library screening identified pyrvinium to be effective against MLL-rearranged AML.

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Pyrvinium targets the mitochondria of MLL-rearranged AML cells.

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Pyrvinium does not antagonize with standard chemotherapy in MLL-rearranged AML.

Pediatric MLL-rearranged acute myeloid leukemia (AML) has a generally unfavorable outcome, primarily due to relapse and drug resistance. To overcome these difficulties, new therapeutic agents are urgently needed. Yet, implementing novel drugs for clinical use is a time-consuming, laborious, costly and high-risk process. Therefore, we applied a drug-repositioning strategy by screening drug libraries, comprised of >4000 compounds that are mostly FDA-approved, in a high-throughput format on primary MLL-rearranged AML cells. Here we identified pyrvinium pamoate (pyrvinium) as a novel candidate drug effective against MLL-rearranged AML, eliminating all cell viability at <1000 nM. Additional screening of identified drug hits on non-leukemic bone marrow samples, resulted in a decrease in cell viability of ∼50% at 1000 nM pyrvinium, suggesting a therapeutic window for targeting leukemic cells specifically. Validation of pyrvinium on an extensive panel of AML cell lines and primary AML samples showed comparable viabilities as the drug screen data, with pyrvinium achieving IC₅₀ values of <80 nM in these samples. Remarkably, pyrvinium also induced cell toxicity in primary MLL-AF10⁺ AML cells, an MLL-rearrangement associated with a poor outcome. While pyrvinium is able to inhibit the Wnt pathway in other diseases, this unlikely explains the efficacy we observed as β-catenin was not expressed in the AML cells tested. Rather, we show that pyrvinium co-localized with the mitochondrial stain in cells, and hence may act by inhibiting mitochondrial respiration. Overall, this study shows that pyrvinium is highly effective against MLL-rearranged AML in vitro, and therefore represents a novel potential candidate for further studies in MLL-rearranged AML.

Treatment Outcomes of Pediatric Acute Myeloid Leukemia in the Yeungnam Region: A Multicenter Retrospective Study of the Study Alliance of Yeungnam Pediatric Hematology-Oncology (SAYPH)

Acute myeloid leukemia (AML) is the second most common pediatric leukemia, with a survival rate of 70%. In this retrospective study, we evaluated the treatment outcomes of pediatric AML among 144 patients diagnosed between 2000 and 2013. After induction, 80.6% of patients achieved complete remission (CR). The 5-year overall survival (OS) and event-free survival (EFS) rates were 58.8 ± 4.2% and 49.8 ± 4.2%, respectively. Based on the response to induction therapy, the 5-year OS was 66.9 ± 5.7% in patients with CR (p < 0.001). Ninety-nine patients with CR after induction therapy were examined, and their 5-year OS and EFS were 66.4 ± 4.9% and 56.3 ± 5.1%, respectively. The 5-year OS rates according to treatment were 59.9 ± 7.4% in the chemotherapy group and 72.3 ± 6.3% in the hematopoietic stem cell transplantation (HSCT) group (p = 0.089). The EFS was 50.1 ± 7.4% in the chemotherapy group and 61.7 ± 6.9% in the HSCT group (p = 0.098). OS and EFS according to cytogenetics were insignificant. Our findings confirmed that the response to induction treatment was important for survival and HSCT had no significant survival benefits compared with those of chemotherapy. Moreover, many early induction deaths under the age of 2 years were observed.

A compound combination screening approach with potential to identify new treatment options for paediatric acute myeloid leukaemia

Paediatric acute myeloid leukaemia (AML) is a heterogeneous disease characterised by genetics and morphology. The introduction of intensive chemotherapy treatments together with patient stratification and supportive therapy has resulted in a moderate improvement in patient prognosis. However, overall survival rates remain unacceptably poor, with only 65% of patients surviving longer than 5 years. Recently age-specific differences in AML have been identified, highlighting the need for tailored treatments for paediatric patients. Combination therapies have the potential to improve patient prognosis, while minimising harmful side-effects. In the laboratory setting, identifying key combinations from large drug libraries can be resource-intensive, prohibiting discovery and translation into the clinic. To minimise redundancy and maximise discovery, we undertook a multiplex screen of 80 apoptotic-inducing agents in paediatric AML pre-clinical models. The screen was designed using an all-pairs testing algorithm, which ensured that all pairs of compounds could be tested, while minimising the number of wells used. We identified a combination of ABT-737, a Bcl-2 family inhibitor and Purvalanol A, a CDK inhibitor, as a potential targeted therapy for AML patients with an MLL rearrangement and an FLT3-ITD. Our approach has the potential to reduce resource-intensity and time associated with the identification of novel combination therapies.

Oral Manifestations and Complications in Childhood Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a heterogeneous group of diseases, whose classification is based on lineage-commitment and genetics. Although rare in childhood, it is the most common type of acute leukemia in adults, accounting for 80% of all cases in this age group. The prognosis of this disease remains poor (especially in childhood, as compared to acute lymphoblastic leukemia); however, overall survival has significantly improved over the past 30 years. The health of the oral cavity is a remarkable reflection of the systemic status of an individual. Identification of the signs and symptoms of oral lesions can act as a warning sign of hidden and serious systemic involvement. Moreover, they may be the presenting feature of acute leukemia and provide important diagnostic indicators. Primary oral alterations are identified in up to 90% of cases of acute myeloid leukemia and consist of petechiae, spontaneous bleeding, mucosal ulceration, gingival enlargement with or without necrosis, infections, hemorrhagic bullae on the tongue, and cracked lips. Poor oral hygiene is a well-known risk factor for local and systemic infectious complications. Oro-dental complications due to AML treatment can affect the teeth, oral mucosa, soft and bone tissue, and contribute to opportunistic infections, dental decay, and enamel discoloration. The treatment of acute myeloid leukemia is still associated with high mortality and morbidity. The management is multimodal, involving aggressive multidrug chemotherapy and, in most cases, allogenic bone marrow transplantation. Periodontal and dental treatment for patients with leukemia should always be planned and concerted with hematologists.