Chronic Myeloid Leukemia Drug Research Articles

Ponatinib-Related Vasospastic Angina.

Tyrosine kinase inhibitors (TKIs) are essential drugs for chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia. Cardiovascular or arteriothrombotic adverse events have been reported in patients treated with TKIs. We report 3 cases of Ponatinib-related vasospastic angina, in which prophylactic administration of nitrates or calcium channel blockers was effective.

Role of Lama4 Expression in Bone Marrow Niche for the Progression and Treatment Response of Chronic Myeloid Leukemia

Although tyrosine kinase inhibitors (TKIs) have dramatically improved the treatment outcomes of chronic myeloid leukemia (CML), TKIs cannot eliminate CML-initiating stem cells (LSCs), leading to CML persistence and relapse post TKI-discontinuation. Thus, it is imperative to develop more effective therapeutic options to overcome the treatment challenges. Targeting the bone marrow (BM) niche has become one of the research focuses in drug discovery since increasing evidence suggests that BM niches protect CML LSCs. Laminin alpha4 chain (Lama4), a functional chain for several laminin isoforms, is widely expressed in bone marrow (BM). We have recently shown the critical impact of LAMA4 expression in the microenvironment for hematopoiesis regeneration including megakaryocyte maturation and acute myeloid leukemia progression in mice (Cai et al., Blood, 2022). Furthermore, we have by RNA sequencing shown downregulation of LAMA4 mRNA in freshly isolated BM mesenchymal stem cells (MSCs) from newly diagnosed patients with CML (Dolinska, Cai, Mansson, et al., Blood, 2023). However, the functional impact of the LAMA4 expression on CML LSCs remains to be investigated. We have here explored the role of LAMA4 in CML development and drug response by using both mouse models and primary patient BM samples. To first assess the in vivo impact of LAMA4 expression in BM niches on CML development, we transplanted BM cells (CD45.2) from Scl- tTA× TRE-BCR-ABL1 (BCR-ABL1) mice prior or following tetracycline withdrawal into irradiated Lama4 +/+ and Lama4 -/- CD45.1mice and analyzed CML progression and BCR-ABL1 LSC activity by flow cytometry and droplet digital PCR (ddPCR). Following transplantation of unfractionated BM cells from the BCR-ABL1 mice with CML induced by tetracycline withdrawal, Lama4 -/- recipients showed significantly increased platelet counts in blood compared to Lama4 +/+ recipients at 2-8 weeks post-transplantation (P=0.005 at week 2, P= 0.008, n=7-8, at week 8), which is in contrast to the impaired platelet recovery in non-transplanted Lama4 -/- mice following sublethal irradiation. This suggests that Lama4 deficient microenvironment is favorable for platelet production from BCR-ABL1 CML cells. Consistent with this, megakaryocyte-erythrocyte progenitors (MEPs) derived from BCR-ABL1 + cells were significantly increased in Lama4 -/- BM at the endpoint (8 weeks, p=0.02, n=3). Megakaryocyte progenitors (MkPs) seemed to be increased in Lama4 -/- recipient BM (P=0.05, n=3). Intriguingly, when LIN -SCA1 +KIT + CD150 + hematopoietic stem cells from BCR-ABL1 mice without prior tetracycline withdrawal were transplanted, the donor-derived MEPs were significantly reduced in Lama4 -/- BM (P=0.02, n=4-6), which is accompanied with a trend of reduction in MkP but no changes in platelets. ddPCR analysis indicated that the ratio of BCR-ABL1 + cell fraction to total CD45.2 + cells (detected by FACS) seemed to be lower in Lama4 -/- recipients (33.6%) than that in Lama4 +/+ recipients (41.5%), raising a possibility that Lama4 -/- niches is less suitable for maintenance of BCR-ABL1 + cells. Together, these data point to a possible differential regulation of CML stem and progenitor cells by the Lama4 expression. More work will be done to dissect the regulatory mechanisms through in vitro co-cultures, transplantation and confocal imaging. In parallel, the functional impact of LAMA4 on human CML LSC survival was evaluated by a revised long-term culture-initiating cell assay using CML patient derived MSCs. The preliminary result indicated that recombinant LAMA4 peptides appeared to inhibit CML patient BM-derived CD34 +CD38 - cell growth. In conclusion, LAMA4 is downregulated in BM MSCs and endothelial cells of CML patients at diagnosis. Lama4 -/- microenvironment might act differentially in regulating BCR-ABL1 + hematopoietic stem and progenitor cell activity post-transplantation. However, more work is required to validate the finding and the effect of LAMA4 peptides on the megakaryocyte differentiation and maturation.

System analysis of Huang-Lian-Jie-Du-Tang and their key active ingredients for overcoming CML resistance by suppression of leukemia stem cells

BackgroundBCR-ABL1-based resistance to imatinib, mainly resulting from BCR-ABL1 mutations, is largely solved after second- and third-generation tyrosine kinase inhibitors (TKIs) are discovered. Nonetheless, imatinib resistance without BCR-ABL1 mutations, including intrinsic resistance induced by stem cells within chronic myeloid leukemia (CML), remains the major clinical challenge for many patients. PurposeTo study the key active ingredients and corresponding target proteins in Huang-Lian-Jie-Du-Tang (HLJDT) against BCR-ABL1-independent CML resistance to therapeutics, and then explore its mechanism of against CML drug resistance. MethodsCytotoxicity of HLJDT and its active ingredients in BCR-ABL1-independent imatinib resistance cells was analyzed through MTT assay. The cloning ability was measured through soft agar assay. Monitoring therapeutic effect on Xenografted mice CML model by in vivo imaging technology and mice survival time. Predicting the potential target protein binding sites by the technology of photocrosslinking sensor chip, molecular space simulation docking, and use Surface Plasmon Resonance (SPR) technology . Flow cytometry to detect the ratio of stem progenitor cells (CD34+). Constructing bone marrow transplantation mice CML leukemia model, detect the effects on leukemia stem cells LSK (Lin-\\ Sca-1+ \\C-kit+) self-renewal. ResultsTreatment with HLJDT, berberine and baicalein inhibited cell viability and colony formation of BCR-ABL1-independent imatinib-resistant cells in vitro while prolonging survival in mouse with CML xenografts and transplatation CML-like mouse models in vivo. JAK2 and MCL1were identified as targets of berberine and baicalein. JAK2 and MCL1 are involved in multi-leukemia stem cell-related pathways. Moreover, the ratio of CD34+ cells in resistant CML cells is higher than in treatment-sensitive CML cells. Treatment with BBR or baicalein partially suppressed CML leukemic stem cells (LSCs) self-renewal in vitro and in vivo. ConclusionFrom the above, we concluded that HLJDT and its key active ingredients (BBR and baicalein) allowed to overcome imatinib resistance with BCR-ABL1 independent by eradication of LSCs by targeting the JAK2 and MCL1 protein levels. Our results lay the foundation for applying HLJDT in patients with TKI-resistant CML.

Dasatinib Attenuates Inflammatory Outcomes of the Sepsis Induced Acute Lung Injury Through mTOR Pathway

This study aimed to investigate the therapeutic potential of dasatinib, an FDA-approved drug for chronic myeloid leukemia, in sepsis-induced acute lung injury (ALI). In the in vitro part of the study, RAW 264.7 macrophages were stimulated with lipopolysaccharide (LPS), and the anti-inflammatory effects of dasatinib were assessed by measuring pro-inflammatory mediators and cytokines. In the in vivo part, ALI was induced in mice through intraperitoneal LPS injection. The researchers investigated alveolar-capillary permeability, the inflammatory response, and the therapeutic efficacy of dasatinib in ALI. Dasatinib administration was found to attenuate inflammation by inhibiting the mTOR pathway. In the in vivo experiments, dasatinib reduced the levels of pro-inflammatory cytokines and chemokines in bronchoalveolar lavage fluid (BALF). It also decreased lung tissue permeability, as evidenced by a lower amount of Evans blue dye detected after ALI. Furthermore, dasatinib alleviated lung histological damage and reduced the lung injury grade, demonstrating its protective role in ALI. By inhibiting the mTOR pathway in macrophages, dasatinib exhibited a protective and anti-inflammatory effect on ALI. It reduced the intrapulmonary inflammatory response, prevented capillary disruption, and inhibited the accumulation of inflammatory cells. These findings suggest that dasatinib holds promise as a potential treatment option for protecting lung tissue in ALI.

The m6A regulator KIAA1429 stabilizes RAB27B mRNA and promotes the progression of chronic myeloid leukemia and resistance to targeted therapy

Chronic myeloid leukemia (CML) is a common adult leukemia. Both the acute phase of the disease and the adverse effects of anti-cancer treatments can lead to a poor prognosis. The N6-methyladenine (m6A) modification plays an important regulatory role in various physiological and pathological processes. KIAA1429 is a known m6A regulator, but the biological role of KIAA1429 in CML is unclear. In this study, we observed that the m6A levels and KIAA1429 expression were significantly up-regulated in patients with blast phase CML. Notably, KIAA1429 regulated the total level of RNA m6A modification in the CML cells and promoted the malignant biological behaviors of CML cells, including proliferation, migration, and imatinib resistance. Inhibiting KIAA1429 in CML cells reduced the stability of RAB27B mRNA through the m6A/YTHDF1 axis, consequently inhibiting CML proliferation and drug efflux, ultimately increasing the sensitivity of CML cells to imatinib. Moreover, the knockdown of RAB27B also inhibited the proliferation and drug resistance of CML cells and promoted their apoptosis. Rucaparib, a recently developed anti-cancer agent, suppressed the expression of KIAA1429 and CML cell proliferation and promoted cell apoptosis. Rucaparib also inhibited the tumorigenesis of CML cells in vivo. The combined use of rucaparib and imatinib enhanced the sensitivity of CML cells to imatinib. Our study provides evidence that elevated KIAA1429 expression in the blast phase of CML enhances the stability of RAB27B mRNA through the m6A/YTHDF1 axis to up-regulate RAB27B expression, thereby promoting CML progression. Rucaparib exerts inhibitory effects on KIAA1429 expression and thus reduces CML progression.

Discovery of CZS-241: A Potent, Selective, and Orally Available Polo-Like Kinase 4 Inhibitor for the Treatment of Chronic Myeloid Leukemia

Recent studies demonstrate that PLK4 has emerged as a therapeutic target for the treatment of multiple cancers owing to its indispensable role in cell division. Herein, starting from previously identified effective compound CZS-034, based on rational drug design strategies, tyrosine kinase receptor A (TRKA) selectivity- and metabolic stability-guided structure-activity relationship (SAR) exploration were carried out to discover a highly potent (IC50 = 2.6 nM) and selective (SF = 1054.4 over TRKA) PLK4 inhibitor B43 (CZS-241) with acceptable human liver microsome stability (t1/2 = 31.5 min). Moreover, compound B43 effectively inhibited leukemia cells in 29 tested cell lines, especially chronic myeloid leukemia (CML) cell lines K562 and KU-812. Pharmacokinetic characteristics revealed that compound B43 possessed over 4 h of half-life and 70.8% bioavailability in mice. In the K562 cells xenograft mouse model, a 20 mg/kg/day dosage treatment obviously suppressed tumor progression. As a potential and novel PLK4-targeted candidate drug for CML, compound B43 is undergoing extensive preclinical safety evaluation.

Intracellular angiopoietin-1 promotes TKI-resistance via activation of JAK/STAT5 pathway in chronic myeloid leukemia.

Drug resistance from BCR-ABL tyrosine kinase inhibitors (TKIs) and other chemotherapeutics results in treatment failure and disease progression in chronic myeloid leukemia (CML). However, the mechanism is still uncertain. In this study, we investigated the role of angiopoietin-1 (ANG-1) as a potential prognostic factor for drug resistance in CML. Both intracellular and secretory ANG-1 (iANG-1 and sANG-1) were overexpressed in multidrug-resistant CML samples. The IC50 value was higher in primary CD34+ CD38- cells with more ANG-1. Silencing ANG-1significantly sensitized three TKI-resistant CML cell lines to imatinib (IM) while recombinant human ANG-1 failed to retain cell survival in vitro. This indicated the important role of iANG-1 as opposed to sANG-1 in CML drug resistance. Moreover, a similar effect was observed in xenograft mice models bearing ANG-1-silenced CML cells. Subsequently, pathway analysis and protein validation experiments showed activation of the JAK/STAT pathway and augmentation of STAT5a phosphorylation in ANG-1 restored CML cells. Upstream Src phosphorylation, which plays a crucial role in CML drug resistance, was also upregulated as a key event in iANG-1-related JAK/STAT pathway activation. In conclusion, our study elucidated a new BCR-ABL independent molecular mechanism induced by intracytoplasmic ANG-1 overexpression as a potential strategy for overcoming CML resistance.

Identification of Potent ABL Inhibitors from Coumestrol: An Integrative In Silico Approach

Chronic Myeloid Leukemia (CML) is known as clonal myeloproliferative disorder resulted by the proliferative and deregulated expression of the BCR-ABL gene. Although targeting the BCR-ABL gene is an effective treatment for CML, the development of drug intolerance and drug resistance is still an issue for BCR-ABL targeted therapy. With an aim to develop novel BCR-ABL inhibitors with fewer side effects, we started with the anti-cancerous natural compound coumestrol as the lead. Chalcone and pyrazole are the well-exploited scaffolds in the anticancer domain; hence, in this work, we designed novel coumestrol derivatives with these structures. In order to quantify the structural changes, we employed in silico methods. The new drug leads were compared with the FDA-approved CML drug bosutinib. The molecular orbital analysis of the selected lead compounds was assessed by Density Functional Theory (DFT) approach. Molecular Dynamic (MD) computations were performed on the most promising leads to find the stability. Following which, the pharmacokinetics parameters of the screened compounds were also analyzed to check the drug-like property.

Abstract P3139: A Pluripotent Stem Cell Model Of Nilotinib-induced Arterial Disease

Nilotinib is a highly effective tyrosine kinase inhibitor used to treat Chronic Myeloid Leukemia (CML). While nilotinib successfully treats CML, a common and serious side effect is development of nilotinib-induced arterial disease (NAD) even in patients without pre-existing risk factors. This side effect is not seen with imatinib, a CML drug in the same class that inhibits the same target as nilotinib. To date, the mechanisms of NAD are unknown, and the cell types involved in this adverse effect have yet to be identified. Furthermore, no tools currently exist to predict which patients will develop NAD. In this study, we used endothelial and vascular smooth cells derived from human-induced pluripotent stem cells (hiPSCs) as a model to identify which cell types are involved in NAD and which cellular functions are perturbed. We first developed a set of efficient, reproducible endothelial and vascular smooth muscle differentiation and purification protocols that consistently yield >95% pure cells. For both hiPSC-derived endothelial cells (hiPSC-ECs) and hiPSC-derived vascular smooth muscle cells (hiPSC-VSMCs) we next identified a panel of assays relevant to various functions of atherogenesis. In comparing the effects of nilotinib and imatinib on hiPSC-ECs, we see a nilotinib-specific decrease in cell capacity for proliferation and migration, in addition to disturbances in Ac-LDL uptake and NO homeostasis. Nilotinib is not differentially toxic to hiPSC-ECs compared to imatinib and has no effect on barrier function as measured by multielectrode array. The data collected to date demonstrate the feasibility of using hiPSCs to model NAD in vitro and recapitulate the clinical discrepancy in vascular effects between nilotinib and imatinib.

Novel Mechanism by a Bis-Pyridinium Fullerene Derivative to Induce Apoptosis by Enhancing the MEK-ERK Pathway in a Reactive Oxygen Species-Independent Manner in BCR-ABL-Positive Chronic Myeloid Leukemia-Derived K562 Cells.

In the treatment of breakpoint cluster region-Abelson (BCR-ABL)-positive chronic myeloid leukemia (CML) using BCR-ABL inhibitors, the appearance of a gatekeeper mutation (T315I) in BCR-ABL is a serious issue. Therefore, the development of novel drugs that overcome acquired resistance to BCR-ABL inhibitors by CML cells is required. We previously demonstrated that a bis-pyridinium fullerene derivative (BPF) induced apoptosis in human chronic myeloid leukemia (CML)-derived K562 cells partially through the generation of reactive oxygen species (ROS). We herein show that BPF enhanced the activation of the mitogen-activated protein kinase/extracellular signal-regulated kinase kinase-extracellular signal-regulated kinase (MEK-ERK) pathway in a ROS-independent manner. BPF-induced apoptosis was attenuated by trametinib, suggesting the functional involvement of the MEK-ERK pathway in apoptosis in K562 cells. In addition, the constitutive activation of the MEK-ERK pathway by the enforced expression of the BRAFV600E mutant significantly increased the sensitivity of K562 cells to BPF. These results confirmed for the first time that BPF induces apoptosis in K562 cells through dual pathways—ROS production and the activation of the MEK-ERK pathway. Furthermore, BPF induced cell death in transformed Ba/F3 cells expressing not only BCR-ABL but also T315I mutant through the activation of the MEK-ERK pathway. These results indicate that BPF is as an effective CML drug that overcomes resistance to BCR-ABL inhibitors.

Clinical Characteristics and Late-Line Treatment Patterns of Patients with Chronic Myeloid Leukemia Who Received 2 Prior Lines of Tyrosine Kinase Inhibitor Therapy in US Community Oncology Practices

BACKGROUND: Current treatment guidelines recommend tyrosine kinase inhibitors (TKIs) as first-line and second-line treatment options for patients with chronic myeloid leukemia (CML). 1,2 However, approximately 20% of CML patients fail to respond to the first- and second-generation TKIs, and evidence-based guidelines for late-line treatment options after failure/intolerance to TKIs are limited. 3,4 Therefore, this study sought to describe the clinical characteristics and real-world treatment patterns of CML patients who received 2 prior lines of TKI therapy.METHODS: A retrospective cohort design was utilized to identify adult CML patients who initiated a new line of therapy (LOT) after 2 prior lines of TKI therapy between 4/2013 and 12/2020 in the Florida Cancer Specialists network's electronic health records (EHR) database. The index LOT date was the start date of a new CML treatment regimen in LOT≥3 after 2 prior lines of TKI therapy. Patients were followed until 1 of the following occurred: death, loss to follow-up (last structured activity in EHR), or end of study period (3/31/2021). Demographic and clinical characteristics were captured during the baseline period starting 3 months prior to the initial CML diagnosis until the index LOT date and included age, gender, race, Eastern Cooperative Oncology Group performance status (ECOG PS) and comorbidity burden. Treatment patterns of all available LOTs from initial CML diagnosis were investigated and the following metrics were captured: regimen details of systemic CML therapies, duration of LOT, treatment-free interval. This study was descriptive in nature and no inferential statistics were computed.RESULTS: A total of 157 patients who initiated a new CML treatment regimen in LOT≥3 after 2 previous lines of TKI therapy were included in this study. The median age of the study sample at initial CML diagnosis was 63.8 years, 57.3% of the sample were male, and 50.3% were White. At index LOT, 46.5% of the sample had an ECOG PS score of 0-1, 5.1% had ECOG PS score of 2-4, and 48.4% had an unknown ECOG PS score. The majority of the sample initiated the index LOT in LOT 3 (n=151; 96.2%) vs in LOT 4 (n=6; 3.8%). The median duration of the index LOT was 6.6 months with median follow-up from index LOT being 23.0 months. After 2 prior lines of TKI therapy, 93.0% of the sample continued on TKIs only, 1.3% initiated a non-TKI CML drug, and 5.7% received a combination of CML drugs. Dasatinib (31.2%) and imatinib (30.6%) were the most commonly used TKIs in the index LOT. There was significant variability in the treatment sequences across LOTs, however, 50.3% of the sample restarted the same TKI in their index LOT which had been used in a prior LOT. A total of 65 patients (41.4%) initiated a new LOT after the index LOT, and the treatment-free interval following the index LOT was 1.8 months, on average.CONCLUSIONS: The majority of the CML patients who received 2 prior lines of TKI therapy continue to cycle through additional LOTs containing TKIs, and half of the patients restart the same TKI used in a prior LOT. The findings of this study highlight the need for better novel therapies that can fill the treatment gap for CML patients who are refractory or intolerant to TKIs. REFERENCES1. Deininger MW, Shah NP, Altman JK, et al. Chronic Myeloid Leukemia, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology. J Natl Compr Canc Netw. 2020;18(10):1385-1415.2. Hochhaus A, Saussele S, Rosti G, et al. Chronic myeloid leukaemia: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Ann Oncol. 2017;28(suppl 4):iv41-iv51.3. Perrotti D, Jamieson C, Goldman J, et al. Chronic myeloid leukemia: mechanisms of blastic transformation. J Clin Invest. 2010;120(7):2254-2264.4. Cortes J, Lang F. Third-line therapy for chronic myeloid leukemia: current status and future directions. J Hematol Oncol. 2021;14(1):44. DisclosuresPatel: Novartis Pharmaceuticals Corporation: Research Funding. Raju: Xcenda LLC: Current Employment, Other: Xcenda LLC received research funding from Novartis Pharmaceuticals Corporation. Coutinho: Xcenda LLC: Current Employment, Other: Xcenda LLC received research funding from Novartis Pharmaceuticals Corporation. Maegawa: Novartis Pharmaceuticals Corporation: Current Employment, Current equity holder in publicly-traded company. Lunacsek: Xcenda LLC: Current Employment, Other: Xcenda LLC received research funding from Novartis Pharmaceuticals Corporation. Deyoung: Xcenda LLC: Current Employment, Other: Xcenda LLC received research funding from Novartis Pharmaceuticals Corporation. Iorga: Novartis Pharmaceuticals Corporation: Current Employment, Current equity holder in publicly-traded company. Cao: Novartis Pharmaceuticals Corporation: Current Employment, Current equity holder in publicly-traded company.

New Drug for Chronic Myeloid Leukemia Might Stimulate the Market.

The evolution of treatment options over the past 20 years has provided for a normal life expectancy for most patients with chronic myeloid leukemia. Currently approved tyrosine kinase inhibitors mainly differ in potency and side effect profile. Flumatinib goes for deep responses and good tolerability.See related article by Zhang et al., p. 70.

Exosomes from Bone Marrow Microenvironment-Derived Mesenchymal Stem Cells Affect CML Cells Growth and Promote Drug Resistance to Tyrosine Kinase Inhibitors.

Although major advances have been achieved in the treatment of chronic myeloid leukemia (CML) by using tyrosine kinase inhibitors, patients relapse after withdrawal and need long-term medication. This reflects the CML clones have not been eliminated completely. The precise mechanisms for the maintenance of CML cells are not yet fully understood. The bone marrow microenvironment constitutes the sanctuary for leukemic cells. Mesenchymal stem cells (MSC) are an important component of the bone marrow microenvironment (BM). It plays an important role in the development and drug resistance of CML. Accumulating evidence indicates that exosomes play a vital role in cell-to-cell communication. We successfully isolated and purified exosomes from human bone marrow microenvironment-derived mesenchymal stem cells (hBMMSC-Exo) by serial centrifugation. In the present study, we investigated the effect of hBMMSC-Exo on the proliferation, apoptosis, and drug resistance of CML cells. The results demonstrated that hBMMSC-Exo had the ability to inhibit the proliferation of CML cells in vitro via miR-15a and arrest cell cycle in the G0/G1 phase. However, the results obtained from BALB/c nu/nu mice studies apparently contradicted the in vitro results. In fact, hBMMSC-Exo increased tumor incidence and promoted tumor growth in vivo. Further study showed the antiapoptotic protein Bcl-2 expression increased, whereas the Caspase3 expression decreased. Moreover, the in vivo study in the xenograft tumor model showed that hBMMSC-Exo promoted the proliferation and decreased the sensitivity of CML cells to tyrosine kinase inhibitors, resulting in drug resistance. These results demonstrated that hBMMSC-Exo supported the maintenance of CML cells and drug resistance in BM by cell-extrinsic protective mechanisms. They also suggested that hBMMSC-Exo might be a potential target to overcome the microenvironment-mediated drug resistance.

WHO 2016 Definition of Chronic Myeloid Leukemia and Tyrosine Kinase Inhibitors

Philadelphia (Ph*)/BCR-ABL1-positive chronic myeloid leukemia (CML) is considered as a chronic life-long disease, which could be manageable with tyrosine kinase inhibitor (TKI) drugs. The aim of TKI drug treatment is to provide age- and sex-matched duration of life in a given patient with CML. Personalized CML treatment with TKI drugs is the key strategy. Individual treatment approach includes the harmonization of CML disease characteristics, clinical experience, and best available clinical evidence. Specific CML disease characteristics in a given patient include; CML disease risk, comorbidities, molecular profile, compliance, lifestyle, and drug off-target risk profile. CML research evidence includes; randomized clinical trials indicating the data on the efficacy, safety, tolerability, toxicity, possible long-term adverse events, and pharmacoeconomy of TKIs. Clinical and physician experience includes TKI availability, TKI reimbursability, drug experience, adherence, and BCR-ABL1 monitorization facilities. The key decision of choosing a TKI of choosing TKIs for CML should be made via the consideration of these variables. The aim of this paper is to outline the latest 2016 World Health Organization definition of CML and its proper management with TKI-class drugs.

Vascular Endothelial Growth Factor Receptor Polymorphisms and im Treatment Response in Chronic Myeloid Leukemia Patients

Abstract Background Imatinib mesylate (IM) is the gold standard drug for chronic myeloid leukemia (CML) treatment. However, intrinsic and acquired resistance against IM has become a problem in CML treatment. Vascular endothelial growth factor receptor 2 (VEGFR2) plays a pivotal role in leukemia associated angiogenesis. Its expression is a good predictor of poor survival in CML. Genetic polymorphisms in VEGFR2 result in varied VEGFR2 expression and may lead to inter individual variation in disease progression and outcome to IM therapy. Aim of this study was to investigate the frequencies of VEGFR2 polymorphisms rs1531289 and rs2305948 in Malaysian CML patients and to determine the impact of these SNPs on IM treatment response in these CML patients. Methods DNA extracted from 230 CML patients (121 IM resistant and 109 IM good response) were genotyped using restriction fragment length polymorphism analysis and genotypes were categorized into homozygous wildtype, heterozygous and homozygous variants. The difference in genotype frequencies of the two SNPs, between the two groups of CML patients were compared using x2 test and the association between genotypes and treatment response was assessed using logistic regression analysis and deriving ORs with 95% CI. Results The SNP rs1531289 did not show any significant association with IM resistance. For rs2305948, the heterozygous variant genotype (CT) and variant allele (T) showed significant association with IM resistance (OR, 2.38; CI,1.33-4.25, p = 0.003 and OR,1.48; CI, 1.02-2.14,p=0.039 respectively). Haplotype analysis of the two SNPs did not show any association with treatment response. Conclusion VEGFR2 polymorphism rs2305948 which is associated with cytogenetic response and development of resistance to IM therapy might be a potential prognostic predictor of IM treatment response in CML patients. This study was financially supported by Research University Grant of Universiti Sains Malaysia, 2017.

PB1916 MIRNAS AND ANGIOGENIC FACTORS IN PLASMA BEFORE AND AFTER TKI TREATMENT IN CML PATIENTS

Background:The differences of an angiogenic potential between clinical phases of chronic myeloid leukemia (CML), point at the significance of neovascularisation in CML pathogenesis. Tyrosine kinase inhibitors (TKI), possessing antiangiogenic properties and microRNAs (miRNAs), implicated in governing angiogenesis, both seem vital in this process.Aims:In this study, we aimed to investigate how TKI treatment affects angiogenesis‐related miRNAs expression and angiogenic factors concentration in plasma of CML patients.Methods:Peripheral blood plasma samples were obtained from CML patients at the diagnosis (n = 23) and during TKI treatment (n = 12). Quantitative assessment of the expression of miRNA‐126‐3p, miRNA‐150‐5p and miRNA‐21‐3p was performed with qRT‐PCR. Concentrations of selected angiogenic factors in plasma (Angiogenin, bFGF, Endostatin,aFGF, PDGF‐AA, PIGF, Thrombospondin‐2, VEGF‐D, Angiopoietin‐1, VEGF) were assessed using multiplex fluorescent bead‐based immunoassays (Luminex Corporation).Results:MiRNA‐150‐5p and miRNA‐21‐3p expression was evidently higher in the treatment group (p = 0,001 and p = 0,03, respectively). PDGF‐AA concentration in newly diagnosed patients with CML was higher than in already treated patients (942,84 pg/ml vs 512,5 pg/ml, p = 0,02), similarly to VEGF (262,82 pg/ml vs 27 pg/ml, p = 0,03).Summary/Conclusion:TKI treatment affects miRNAs expression and angiogenic factors concentration in plasma of CML patients. MiRNAs could serve as biomarkers in monitoring CML progression and drug response, however, their exact role in CML‐related angiogenesis remains to be further elucidated.

Fludarabine as an Adjuvant Improves Newcastle Disease Virus-Mediated Antitumor Immunity in Hepatocellular Carcinoma

In addition to direct oncolysis, oncolytic viruses (OVs) also induce antitumor immunity, also called viro-immunotherapy. Limited viral replication and immune-negative feedback are the major hurdles to effective viro-immunotherapy. In this study, we found that use of an adjuvant of fludarabine, a chemotherapeutic drug for chronic myeloid leukemia, increased the replication of Newcastle disease virus (NDV) by targeting signal transducer and activator of transcription 1 (STAT1), which led to enhanced oncolysis of hepatocellular carcinoma (HCC) cells. Moreover, fludarabine accelerated ubiquitin-proteasomal degradation by enhancing ubiquitylation rather than proteasomal activity. This resulted in accelerated degradation of phosphorylated STAT3 and indoleamine 2, 3-dioxygenase 1 (IDO1), whose expression was induced by NDV infection. In addition, fludarabine significantly increased the NDV-induced infiltration of NK cells and decreased the number of NDV-induced myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment. The aforementioned effects of fludarabine significantly improved NDV-mediated antitumor immunity and prolonged survival in mouse model of HCC. Our findings indicate the utility of fludarabine as an adjuvant for oncolytic anticancer viro-immunotherapy.

MXD1 Regulates the Imatinib Resistance of Chronic Myeloid Leukemiacells By Repressing BCR-ABL1 Expression

Tyrosine kinase inhibitors have achieved unprecedented efficacy in the treatment of chronic myeloid leukemia (CML), however, imatinib resistance has emerged as a major problem in the clinic. Because the overexpression of BCR-ABL1 critically contributes to CML pathogenesis and drug resistance, targeting the regulation of BCR-ABL1 gene expression may be a novel therapeutic strategy. In this study, we found that the transcriptional repressor MXD1 showed low expression in CML patients and was negatively correlated with BCR-ABL1. Overexpression of MXD1 markedly inhibited the proliferation of K562 cells and sensitized the imatinib-resistant K562/G01 cell line to imatinib, with decreased BCR-ABL1 mRNA and protein. Further investigations using reporter gene analysis showed that MXD1 significantly inhibited the transcriptional activity of the BCR-ABL1 gene promoter. Taken together, these data show that MXD1 functions as a negative regulator of BCR-ABL1 expression and subsequently inhibits proliferation and sensitizes CML cells to imatinib treatment. DisclosuresNo relevant conflicts of interest to declare.

MXD1 regulates the imatinib resistance of chronic myeloid leukemia cells by repressing BCR-ABL1 expression

Tyrosine kinase inhibitors have achieved unprecedented efficacy in the treatment of chronic myeloid leukemia (CML); however, imatinib resistance has emerged as a major problem in the clinic. Because the overexpression of BCR-ABL1 critically contributes to CML pathogenesis and drug resistance, targeting the regulation of BCR-ABL1 gene expression may be an alternative therapeutic strategy. In this study, we found that the transcriptional repressor MXD1 showed low expression in CML patients and was negatively correlated with BCR-ABL1. Overexpression of MXD1 markedly inhibited the proliferation of K562 cells and sensitized the imatinib-resistant K562/G01 cell line to imatinib, with decreased BCR-ABL1 mRNA and protein expression. Further investigation using reporter gene analysis showed that MXD1 significantly inhibited the transcriptional activity of the BCR-ABL1 gene promoter. Taken together, these data show that MXD1 functions as a negative regulator of BCR-ABL1 expression and subsequently inhibits proliferation and sensitizes CML cells to imatinib treatment.

MicroRNA-199a/b-5p enhance imatinib efficacy via repressing WNT2 signaling-mediated protective autophagy in imatinib-resistant chronic myeloid leukemia cells

Imatinib (IM) is a first-line therapeutic drug for chronic myeloid leukemia (CML), a hematological disease. Mutations in the BCR-ABL domain increase formation of IM resistance in CML. However, not all patients are BCR-ABL domain-mutant dependent. Investigating non-mutant mechanisms in the development of acquired IM resistance is a critical issue. We explored the mechanisms which influence IM efficacy and resistance in CML. Higher protective autophagy was identified in IM-resistant K562 (K562R) cells. Inhibition of autophagy by the inhibitors, chloroquine and 3-methyladenine, enhanced IM's efficacy in K562R cells. In addition, microRNA (miR)-199a/b-5p were downregulated in K562R cells compared to parent cells. Overexpression of miR-199a/b-5p reduced autophagy and induced cell apoptosis, resulting in enhanced IM's efficacy in K562R cells. Moreover, expression levels of the Wingless-type MMTV integration site family member 2 (WNT2), a positive regulator of autophagy, were significantly higher in K562R cells, and it was validated as a direct target gene of miR-199a/b-5p. Overexpressions of miR-199a/b-5p inhibited WNT2 downstream signaling. Furthermore, overexpression and knockdown of WNT2 influenced autophagy formation and CML drug sensitivity to IM. Overexpression of WNT2 could also reverse miR-199a/b-5p-enhanced IM efficacy in K562R cells. These results emphasized that miR-199a/b-5p inhibited autophagy via repressing WNT2 signaling and might provide novel therapeutic strategies for future IM-resistant CML therapy and drug development.