Chronic myeloid leukemia

Combined Therapy of ATRA and Imatinib Mesylate Decreases BCR-ABL and ABCB1/MDR1 Expression Through Cellular Differentiation in a Chronic Myeloid Leukemia Model

BACKGROUND/AIM

Chronic Myeloid Leukemia (CML) is a clonal myeloproliferative disease, and a major challenge for the eradication of CML is to understand the cause of the permanence of minimal residual disease (DRM). This work aimed to induce the maturation of leukemic stem cells with All-trans-retinoic acid (ATRA), making them sensitive to treatment with Imatinib (IM).

MATERIALS AND METHODS

K562 cells were treated with IM and with the combined therapy of ATRA together with IM for 48 and 72 h. The expression of BCR-ABL gene and multidrug resistance gene ABCB1 were evaluated using RT-qPCR.

RESULTS

The combined ATRA and IM therapy showed a discreet cell differentiation pattern, evidenced by the panoptic morphology analysis at 48 and 72 h of treatment. The BCR-ABL expression showed no statistical difference when treated alone with IM, however in combination with ATRA, the expression was statistically significant in 48 and 72 h (p≤0.0001) and when the treatment groups were compared to each other (p≤0.001). The ABCB1 gene expression showed a decrease in isolated IM therapy (p≤0.05) and in the combination in 48 and 72 h (p≤0.0001).

CONCLUSION

Combined ATRA and IM therapy was shown to be effective in decreasing BCR-ABL and ABCB1 genes, possibly through the differentiation of blast cells, demonstrating that the therapy could be potentially effective in the blast crisis of the disease and for those patients who develop resistance to available CML treatments.

Pharmacologic and genetic inhibition of cholesterol esterification enzymes reduces tumour burden: A systematic review and meta-analysis of preclinical models

Cholesterol esterification proteins Sterol-O acyltransferases (SOAT) 1 and 2 are emerging prognostic markers in many cancers. These enzymes utilise fatty acids conjugated to coenzyme A to esterify cholesterol. Cholesterol esterification is tightly regulated and enables formation of lipid droplets that act as storage organelles for lipid soluble vitamins and minerals, and as cholesterol reservoirs. In cancer, this provides rapid access to cholesterol to maintain continual synthesis of the plasma membrane. In this systematic review and meta-analysis, we summarise the current depth of understanding of the role of this metabolic pathway in pan-cancer development. A systematic search of PubMed, Scopus, Web of Science, and Cochrane Library for preclinical studies identified eight studies where cholesteryl ester concentrations were compared between tumour and adjacent-normal tissue, and 24 studies where cholesterol esterification was blocked by pharmacological or genetic approaches. Tumour tissue had a significantly greater concentration of cholesteryl esters than non-tumour tissue (p < 0.0001). Pharmacological or genetic inhibition of SOAT was associated with significantly smaller tumours of all types (p ≤ 0.002). SOAT inhibition increased tumour apoptosis (p = 0.007), CD8 + lymphocyte infiltration and cytotoxicity (p ≤ 0.05), and reduced proliferation (p = 0.0003) and metastasis (p < 0.0001). Significant risk of publication bias was found and may have contributed to a 32% overestimation of the meta-analysed effect size. Avasimibe, the most frequently used SOAT inhibitor, was effective at doses equivalent to those previously reported to be safe and tolerable in humans. This work indicates that SOAT inhibition should be explored in clinical trials as an adjunct to existing anti-neoplastic agents.

Molecular, Cytogenetic, and Hematological Analysis of Chronic Myeloid Leukemia Patients and Discovery of Two Novel Translocations

Chronic myeloid leukemia (CML) is a disease of hematopoietic stem cells and is caused by the balanced translocations among the long arms of chromosomes 9 and 22, which are called the Philadelphia (Ph) chromosome. In this study, 131 CML patients were enrolled. Complete blood cell count was performed at the time of diagnosis for all the patients. Cytogenetic (karyotyping) examination using bone marrow samples was conducted on 76 CML patients for the confirmation of Ph-positive (9;22)(q34;q11) standard translocation, complex variant translocation, and additional chromosome abnormalities. FISH was performed on 38 patients for diagnostic purposes and on 39 patients for monitoring purposes. Twenty-two samples of CML patients were evaluated by reverse transcriptase PCR and real-time PCR for the patients who failed to respond against imatinib mesylate. In this study, 72 (54.96%) were males and 59 (45.03%) were females with a median age of 38.5 years. CBC values in the diagnosis process showed that 75 patients had high values of WBC being >100 × 103/μl, while 71 (58.01) patients exhibited reduced values of hemoglobin, i.e., <10.00 mg/dl, and high values of PLTs > 100 were observed in 40 (30.53%) patients. Cytogenetic results show that standard translocation was developed in 63 (82.89%), development of complex variant translocations in 4 (5.32%), additional chromosomal abnormalities (ACAs) in 3 (3.94%), and ACAs together with complex variant translocations in 1 (1.31%) patient. At the time of diagnosis, 61 (92.95%) patients were in the chronic phase, 4 (5.63%) were in the accelerated phase, and only 1 (1.40%) was in the blast crisis. Out of twenty-two patients, only 6 CML patients who were shifted from imatinib mesylate to nilotinib showed BCR-ABL-positive amplification. However, only 7 out of twenty-one patients exhibit BCR-ABL gene values ≥ 1 after three months of follow-up when analyzed by the quantitative real-time PCR. In conclusion, we found a novel five-way translocation 46XX,t(1;2;2;17;9;22)(p36.3,q21;q11.2,q21,q34,q11.2) and a novel four-way complex variant translocation 48XY,+8(8;17)(9;22),+der(22)(q11.2;q23)(q34;q11.2) in the accelerated phase.

Cancer Biomarkers in the era of precision oncology: Addressing the needs of patients and health systems

Cancer Biomarkers are the key to unlocking the promise of precision oncology, selecting which patients will respond to a more personalised treatment while sparing non-responders the therapy-related toxicity. In this paper, we highlight the primacy of cancer biomarkers, but focus on their importance to patients and to health systems. We also highlight how cancer biomarkers represent value for money. We emphasise the need for cancer biomarkers infrastructure to be embedded into European health systems. We also highlight the need to deploy multiple biomarker testing to deliver the optimal benefit for patients and health systems and consider cancer biomarkers from the perspective of cost, value and regulation. Cancer biomarkers must also be situated in the context of the upcoming In Vitro Diagnostics Regulation, which may pose certain challenges (e.g. non-compliance of laboratory developed tests, leading to cancer biomarker shortages and increased costs) that need to be overcome. Cancer biomarkers must be embedded in the real world of oncology delivery and testing must be implemented across Europe, with the intended aim of narrowing, not widening the inequity gap for patients. Cancer patients must be placed firmly at the centre of a cancer biomarker informed precision oncology care agenda.

Molecular insights on ABL kinase activation using tree-based machine learning models and molecular docking

Abelson kinase (c-Abl) is a non-receptor tyrosine kinase involved in several biological processes essential for cell differentiation, migration, proliferation, and survival. This enzyme's activation might be an alternative strategy for treating diseases such as neutropenia induced by chemotherapy, prostate, and breast cancer. Recently, a series of compounds that promote the activation of c-Abl has been identified, opening a promising ground for c-Abl drug development. Structure-based drug design (SBDD) and ligand-based drug design (LBDD) methodologies have significantly impacted recent drug development initiatives. Here, we combined SBDD and LBDD approaches to characterize critical chemical properties and interactions of identified c-Abl's activators. We used molecular docking simulations combined with tree-based machine learning models-decision tree, AdaBoost, and random forest to understand the c-Abl activators' structural features required for binding to myristoyl pocket, and consequently, to promote enzyme and cellular activation. We obtained predictive and robust models with Matthews correlation coefficient values higher than 0.4 for all endpoints and identified characteristics that led to constructing a structure-activity relationship model (SAR).

Downregulation of miR-142a Contributes to the Enhanced Anti-Apoptotic Ability of Murine Chronic Myelogenous Leukemia Cells

Background

Leukemic stem cell (LSC) is thought to be responsible for chronic myelogenous leukemia (CML) initiation and relapse. However, the inherent regulation of LSCs remains largely obscure. Herein, we integratedly analyzed miRNA and gene expression alterations in bone marrow (BM) Lin^-Sca1⁺c-Kit⁺ cells (LSKs) of a tet-off inducible CML mouse model, Scl/tTA-BCR/ABL (BA).

Methods

Scl/tTA and TRE-BA transgenic mice were crossed in the presence of doxycycline to get double transgenic mice. Both miRNA and mRNA expression profiles were generated from BM LSKs at 0 and 3 weeks after doxycycline withdrawal. The target genes of differentially expressed miRNAs were predicted, followed by the miRNA-mRNA network construction. In vitro and in vivo experiments were further performed to elucidate their regulation and function in CML progression.

Results

As a result of the integrated analysis and experimental validation, an anti-apoptotic pathway emerged from the fog. miR-142a was identified to be downregulated by enhanced ERK-phosphorylation in BA-harboring cells, thereby relieving its repression on Ciapin1, an apoptosis inhibitor. Moreover, miR-142a overexpression could partially rescue the abnormal anti-apoptotic phenotype and attenuate CML progression.

Conclusion

Taken together, this study explored the miRNA-mRNA regulatory networks in murine CML LSKs and demonstrated that ERK-miR-142a-Ciapin1 axis played an essential role in CML pathogenesis.

The potentiation of menadione on imatinib by downregulation of ABCB1 expression

Imatinib was the first BCR-ABL inhibitor used in clinical practice to treat chronic myeloid leukaemia (CML) and significantly improve the life expectancy of CML patients in the chronic phase. However, a portion of CML patients are resistant to imatinib. This study aimed to determine whether menadione (Vitamin K3) can improve imatinib efficacy in CML and to thoroughly explore the combination regimen mechanism between imatinib and menadione. Menadione improved imatinib efficacy in K562 cells by downregulating ABCB1 expression and increased the intracellular concentration of imatinib, which confirmed that this combination regimen is more effective than imatinib monotherapy. The results demonstrate that menadione and imatinib combination therapy may be a promising approach to refractory CML.

Nilotinib-induced bone marrow CD34+/lin-Ph+ cells early clearance in newly diagnosed CP-Chronic Myeloid Leukemia: Final report of the PhilosoPhi34 study

Chronic Myeloid Leukemia is a clonal disorder characterized by the presence of the Ph‐chromosome and the BCR‐ABL tyrosine‐kinase (TK). Target‐therapy with Imatinib has greatly improved its outcome. Deeper and faster responses are reported with the second‐generation TKI Nilotinib. Sustained responses may enable TKI discontinuation. However, even in a complete molecular response, some patients experience disease recurrence possibly due to persistence of quiescent leukemic CD34+/lin−Ph+ stem cells (LSCs). Degree and mechanisms of LSCs clearance during TKI treatment are not clearly established. The PhilosoPhi34 study was designed to verify the in‐vivo activity and timecourse of first‐line Nilotinib therapy on BM CD34+/lin−Ph+ cells clearance. Eighty‐seven CP‐CML patients were enrolled. BM cells were collected and tested for Ph+ residual cells, at diagnosis, 3, 6 and 12 months of treatment. FISH analysis of unstimulated CD34+/lin− cells in CCyR patients were positive in 8/65 (12.3%), 5/71 (7%), 0/69 (0%) evaluable tests, respectively. Per‐Protocol analysis response rates were as follows: CCyR 95% at 12 months, MR4.5 31% and 46% at 12 and 36 months, respectively. An exploratory Gene Expression Profiling (GEP) study of CD34+/lin− cells was performed on 30 patients at diagnosis and after, on 79 patients at diagnosis vs 12 months of nilotinib treatment vs 10 healthy subjects. Data demonstrated some genes significantly different expressed: NFKBIA, many cell cycle genes, ABC transporters, JAK‐STAT signaling pathway (JAK2). In addition, a correlation between different expression of some genes (JAK2, OLFM4, ICAM1, NFKBIA) among patients at diagnosis and their achievement of an early and deeper MR was observed.

Impact of frontline treatment approach on outcomes of myeloid blast phase CML

Background

The natural course of untreated chronic myeloid leukemia (CML) is progression to an aggressive blast phase. Even in the current era of BCR-ABL1 tyrosine kinase inhibitors (TKIs), the outcomes of blast phase CML remain poor with no consensus frontline treatment approach.

Methods

We retrospectively analyzed the response rates and survival outcomes of 104 consecutive patients with myeloid blast phase CML (CML-MBP) treated from 2000 to 2019 based on 4 different frontline treatment approaches: intensive chemotherapy (IC) + TKI (n = 20), hypomethylating agent (HMA) + TKI (n = 20), TKI alone (n = 56), or IC alone (n = 8). We also evaluated the impact of TKI selection and subsequent allogeneic stem cell transplant (ASCT) on patient outcomes.

Results

Response rates were similar between patients treated with IC + TKI and HMA + TKI. Compared to treatment with TKI alone, treatment with IC/HMA + TKI resulted in a higher rate of complete remission (CR) or CR with incomplete count recovery (CRi) (57.5% vs 33.9%, p < 0.05), a higher complete cytogenetic response rate (45% vs 10.7%, p < 0.001), and more patients proceeding to ASCT (32.5% vs 10.7%, p < 0.01). With a median follow-up of 6.7 years, long-term outcomes were similar between the IC + TKI and HMA + TKI groups. Combination therapy with IC/HMA + TKI was superior to therapy with TKI alone, including when analysis was limited to those treated with a 2nd/3rd-generation TKI. When using a 2nd/3rd-generation TKI, IC/HMA + TKI led to lower 5-year cumulative incidence of relapse (CIR; 44% vs 86%, p < 0.05) and superior 5-year event-free survival (EFS; 28% vs 0%, p < 0.05) and overall survival (OS; 34% vs 8%, p = 0.23) compared to TKI alone. Among patients who received IC/HMA + TKI, EFS and OS was superior for patients who received a 2nd/3rd generation TKI compared to those who received imatinib-based therapy. In a landmark analysis, 5-year OS was higher for patients who proceeded to ASCT (58% vs 22%, p = 0.12).

Conclusions

Compared to patients treated with TKI alone for CML-MBP, treatment with IC + TKI or HMA + TKI led to improved response rates, CIR, EFS, and OS, particularly for patients who received a 2nd/3rd-generation TKI. Combination therapy with IC + TKI or HMA + TKI, rather than a TKI alone, should be considered the optimal treatment strategy for patients with CML-MBP.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13045-021-01106-1.

Vitexin isolated from Prosopis cineraria leaves induce apoptosis in K-562 leukemia cells via inhibition of the BCR-ABL-Ras-Raf pathway

OBJECTIVES

Leukemia is one of the severe cancer types all around the globe. Even though some chemotherapeutic drugs are available for treating leukemia, they have various side effects. As an alternative approach, herbal drugs are focused on current research to overcome leukemia. The present work was conducted to investigate the antileukemic mechanism of active phytochemical vitexin, which was isolated from ethno-medicine (Prosopis cineraria leaf) used by traditional healers of West Bengal, India.

METHODS

Antiproliferative mechanisms of selected phyto-compound against K-562 cells were evaluated using cellular uptake, morphological changes, DNA fragmentation, mitochondrial membrane potential and signaling pathways analysis.

KEY FINDINGS

Vitexin exhibited cytotoxicity by reducing mitochondrial membrane potential (32.40%) and causing DNA fragmentation (84.15%). The western blotting study indicated inhibition of cell survival proteins (BCR, ABL, H-RAS, N-RAS, K-RAS and RAF) and expression of apoptotic proteins (p38, BAX and caspase-9) in leukemia cells upon treatment with vitexin.

CONCLUSIONS

Based on the results, presently investigated phyto-compound vitexin could be considered for developing safe and natural drugs to treat leukemia after conducting suitable preclinical and clinical trials.

Interventions to Improve Adherence to Tyrosine Kinase Inhibitors in Chronic Myeloid Leukemia: A Systematic Review

BACKGROUND

Lack of adherence to tyrosine kinase inhibitors (TKIs) is a significant problem resulting in incomplete cytogenetic response and increased mortality in patients with chronic myeloid leukemia (CML). Few studies have been conducted on interventions to improve adherence. The authors conducted a systematic review to explore studies that examined the impact of strategies to improve TKI adherence among individuals with CML.

METHODS

The first 2 authors completed a systematic literature review according to the guidelines in Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA). Studies (n=2633) conducted between 1980 and 2019 were identified through 3 databases and examined for inclusion/exclusion criteria.

RESULTS

Fourteen studies were identified which met the eligibility criteria. The studies only examined adherence to imatinib, dasatinib, or nilotinib. Ten of the 14 used large data sets (commercial health insurance plans or Surveillance Epidemiology and End Results [SEER] data) for analysis. The majority of the studies used a cohort design. Adherence was defined and measured in a variety of ways with most studies using 80% or higher as adequate adherence. Strategies not focused on health care costs used a multidisciplinary team approach.

CONCLUSION

Development of evidence to improve treatment adherence to TKIs for CML have relied on large data sets rather than prospective trials. Current studies lack patient focused interventions.

Improvement of Neoantigen Identification Through Convolution Neural Network

Accurate prediction of neoantigens and the subsequent elicited protective anti-tumor response are particularly important for the development of cancer vaccine and adoptive T-cell therapy. However, current algorithms for predicting neoantigens are limited by in vitro binding affinity data and algorithmic constraints, inevitably resulting in high false positives. In this study, we proposed a deep convolutional neural network named APPM (antigen presentation prediction model) to predict antigen presentation in the context of human leukocyte antigen (HLA) class I alleles. APPM is trained on large mass spectrometry (MS) HLA-peptides datasets and evaluated with an independent MS benchmark. Results show that APPM outperforms the methods recommended by the immune epitope database (IEDB) in terms of positive predictive value (PPV) (0.40 vs. 0.22), which will further increase after combining these two approaches (PPV = 0.51). We further applied our model to the prediction of neoantigens from consensus driver mutations and identified 16,000 putative neoantigens with hallmarks of 'drivers'.

Understanding the hematopoietic microenvironment in chronic myeloid leukemia: A concise review

Chronic myeloid leukemia (CML) is a myeloproliferative disease that results from the BCR-ABL gene-induced transformation of a primitive hematopoietic cell. This disease has been extensively studied, and, as a result, a very effective therapy has been developed: the tyrosine kinase inhibitors. Although, there is a significant knowledge about the intrinsic biology of CML cells, alterations in their bone marrow microenvironment are not yet completely understood. In this concise review, we summarized recent findings on the composition and function of the bone marrow microenvironment in CML, and their importance in the progression of the disease and treatment resistance.

Chronic Myeloid Leukemia in a Patient with Hepatitis B Virus Infection: A Case Report

Chronic myeloid leukemia (CML) is a myeloproliferative disorder diagnosed by demonstrating the Philadelphia chromosome (Ph) or the BCR-ABL fusion gene. Tyrosine kinase inhibitors (TKIs) are the standard of therapy. There are increasing reports of hepatitis B virus reactivation (HBVr) in patients on this treatment. We report a case of a 46-year-old male patient diagnosed to have CML in the chronic phase and resolved hepatitis B infection. He was treated with imatinib as upfront therapy for CML and with lamivudine as prophylaxis against HBVr. The patient tolerated both treatments well with no adverse effects. The aim is to address the deficiencies in the literature in regard to managing these patients, prevention, and follow-up.

Polycomb Factor PHF19 Controls Cell Growth and Differentiation Toward Erythroid Pathway in Chronic Myeloid Leukemia Cells

Polycomb group (PcG) of proteins are a group of highly conserved epigenetic regulators involved in many biological functions, such as embryonic development, cell proliferation, and adult stem cell determination. PHD finger protein 19 (PHF19) is an associated factor of Polycomb repressor complex 2 (PRC2), often upregulated in human cancers. In particular, myeloid leukemia cell lines show increased levels of PHF19, yet little is known about its function. Here, we have characterized the role of PHF19 in myeloid leukemia cells. We demonstrated that PHF19 depletion decreases cell proliferation and promotes chronic myeloid leukemia (CML) differentiation. Mechanistically, we have shown how PHF19 regulates the proliferation of CML through a direct regulation of the cell cycle inhibitor p21. Furthermore, we observed that MTF2, a PHF19 homolog, partially compensates for PHF19 depletion in a subset of target genes, instructing specific erythroid differentiation. Taken together, our results show that PHF19 is a key transcriptional regulator for cell fate determination and could be a potential therapeutic target for myeloid leukemia treatment.

Highly sensitive fluorescence biosensing of BCR-ABL1 fusion gene based on exponential transcription-triggered hemin catalysis

Simple, sensitive and specific detection of the transcription level of BCR-ABL1 mRNA possesses vital clinical significance in diagnosis and treatment of chronic myeloid leukemia (CML). In this study, an innovative fluorescence biosensing methodology has been developed for sensitive and specific detection of BCR-ABL1 mRNA by integrating high-efficiency of exponential transcription and superior catalytic performance of DNA-grafted hemin. Exponential transcription was triggered by BCR-ABL1 mRNA to produce plenty of RNA products. They can specifically hybridize with circular dual-labeled hemin (DLH) probe to dissociate the intramolecular hemin dimmers into highly active hemin monomers for catalyzing fluorescence substrate tyramine. This exponential transcription-triggered hemin catalysis (ET-HC) strategy showed highly sensitive and specific for BCR-ABL1 detection with a limit of detection at 0.5 aM and a good linear range from 2 aM to 200 fM. This method was successfully applied to directly detect as low as 0.001% e13a2 transcript isoforms from complex genomic RNA extraction. Compared with clinical routine, the overall process is a thermostatic reaction and eliminates additional reverse transcription operation. Therefore, the developed ET-HC strategy might provide a promising alternative tool for precise diagnosis and personalized treatment of CML.

Chronic myeloid leukemia-from the Philadelphia chromosome to specific target drugs: A literature review

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm and was the first neoplastic disease associated with a well-defined genotypic anomaly - the presence of the Philadelphia chromosome. The advances in cytogenetic and molecular assays are of great importance to the diagnosis, prognosis, treatment, and monitoring of CML. The discovery of the breakpoint cluster region (BCR)-Abelson murine leukemia (ABL) 1 fusion oncogene has revolutionized the treatment of CML patients by allowing the development of targeted drugs that inhibit the tyrosine kinase activity of the BCR-ABL oncoprotein. Tyrosine kinase inhibitors (known as TKIs) are the standard therapy for CML and greatly increase the survival rates, despite adverse effects and the odds of residual disease after discontinuation of treatment. As therapeutic alternatives, the subsequent TKIs lead to faster and deeper molecular remissions; however, with the emergence of resistance to these drugs, immunotherapy appears as an alternative, which may have a cure potential in these patients. Against this background, this article aims at providing an overview on CML clinical management and a summary on the main targeted drugs available in that context.

Apoptotic profiling of chronic myeloid leukaemia patients' platelets ex vivo before and after treatment with Imatinib

Chronic myeloid leukaemia (CML) is a malignancy of the haematopoietic stem cells. The first line of treatment for CML, especially in developing countries, remains the first-generation tyrosine kinase inhibitor, Imatinib. Patients with CML are frequently diagnosed with platelet abnormalities. However, the specific mechanism of platelet abnormalities in CML remains unclear and poorly understood. The aim of this study was therefore to determine the apoptotic profiles of CML patients ex vivo on platelets before and after treatment with Imatinib. Blood samples of healthy volunteers and CML patients at diagnosis and after 6 months treatment with Imatinib were collected. Platelet counts, viability and activation were determined. Results showed that CML patients' platelet counts were elevated upon diagnosis and these levels statistically significantly decreased after 6 months of treatment. Platelet activation was significantly increased after 6 months of treatment compared to levels at diagnosis (P-value < .05). Similarly, platelet apoptosis was also increased after 6 months of treatment. Abnormalities in platelet functioning found in this study may partly be due to clonal proliferation of haematopoietic cells in CML patients, specifically of megakaryocyte precursors as well as the inhibition of platelet tyrosine kinase's and the inhibition of platelet-derived growth factor.

Assessment of azithromycin as an anticancer agent for treatment of imatinib sensitive and resistant CML cells

INTRODUCTION

Chronic Myeloid Leukemia (CML) is a hematological disease which is characterized by the presence of BCR-ABL fusion protein. Imatinib (IMA), a tyrosine kinase inhibitor of BCR-ABL, is used as a frontline treatment.Although IMA aids in killing a majority of leukemia cells, it may not kill CML stem cells which are the primary roots of disease and therapy resistance. Recently, antimicrobial drugs have been gaining attention because of their selective targeting of cancer cells. Therefore, we now ask if combinational therapy of IMA with a targeted antimicrobial drug Azithromycin (AZT) can enhance the treatment efficiency in IMA resistant CML.

METHODS

K562S (IMA sensitive) and K562R (IMA resistant) cells were treated with increasing concentrations of AZT to determine its effects on cell proliferation and apoptosis. Cell viability, apoptosis, caspase3/7 activity and P-glycoprotein (Pgp) function were investigated with spectrophotometric MTT assay and flow cytometric Annexin V staining, caspase 3/7 activity, and Rhodamine123 staining assays respectively. The expression levels of pro-apoptotic (BAX, BAD and BIM), anti- apoptotic (BCL-XL and BCL-2) and drug transporter (MDR-1 and MRP-1) genes were assessed with qRT-PCR.

RESULTS

AZT treatment alone inhibited cell viability, induced apoptosis and enhanced caspase 3/7 activity in both K562S and high MDR-1 (Pgp) expressing K562R cells. Moreover, combination of AZT/IMA suppressed cell viability, induced apoptosis and caspase3/7 activity more effectively and significantly compared to K562R cells treated with only IMA or AZT. Furthermore, AZT and AZT/IMA combination decreased Pgp function in K562R cells in comparison with their controls. Based on qRT-PCR data, single AZT and combined AZT/IMA treatment also induced BAX/BCL-2 ratio significantly in both K562S and K562R cells.

CONCLUSION

Single AZT and AZT/IMA combinational treatment can be proposed as a promising and effective treatment strategy for CML. One of the mechanisms underlying the potent anticancer effect of combined AZT/IMA could be its ability to inhibit Pgp function and increase intracellular accumulation of IMA which leads to the induction of apoptosis in K562R cells.

Outgrowth of a CSF3R-mutant clone drives a second myeloproliferative neoplasm in a chronic myeloid leukemia patient: a case report

Background

Chronic myeloid leukemia (CML) and chronic neutrophilic leukemia (CNL) are two myeloproliferative neoplasms with mutually exclusive diagnostic criteria. A hallmark of CML is the Philadelphia chromosome (Ph), which results in a BCR-ABL1 fusion gene and constitutive tyrosine kinase activity. CNL is a Ph-negative neoplasm and is defined in part by the presence of CSF3R mutations, which drive constative JAK/STAT signaling.

Case presentation

Here, we report the exceedingly rare co-occurrence of two granulocytic myeloproliferative neoplasms in a 69-year old male patient. After an initial diagnosis of chronic myeloid leukemia, the patient’s clinical course was shaped by hematologic toxicity, the emergence of treatment-resistant BCR-ABL1 clones, and the expansion of a CSF3R-mutant clone without ABL1 mutations under selective pressure from tyrosine kinase inhibitors. The emergence of the CSF3R-mutant, neutrophilic clone led to the diagnosis of CNL as a second myeloproliferative neoplasm in the same patient.

Conclusions

This is the first reported case of CNL arising subsequent to CML, which occurred under selective pressure from targeted therapy in a patient with complex clonal architecture. Patients with such molecularly complex disease may ultimately benefit from combination therapy that targets multiple oncogenic pathways.

Dual Kinase Targeting in Leukemia

Pharmacological cancer therapy is often based on the concurrent inhibition of different survival pathways to improve treatment outcomes and to reduce the risk of relapses. While this strategy is traditionally pursued only through the co-administration of several drugs, the recent development of multi-targeting drugs (i.e., compounds intrinsically able to simultaneously target several macromolecules involved in cancer onset) has had a dramatic impact on cancer treatment. This review focuses on the most recent developments in dual-kinase inhibitors used in acute myeloid leukemia (AML), chronic myelogenous leukemia (CML), and lymphoid tumors, giving details on preclinical studies as well as ongoing clinical trials. A brief overview of dual-targeting inhibitors (kinase/histone deacetylase (HDAC) and kinase/tubulin polymerization inhibitors) applied to leukemia is also given. Finally, the very recently developed Proteolysis Targeting Chimeras (PROTAC)-based kinase inhibitors are presented.

Expansion of senescent megakaryocyte-lineage cells maintains CML cell leukemogenesis

BCR-ABL, an oncogenic fusion gene, plays a central role in the pathogenesis of chronic myeloid leukemia (CML). Oncogenic signaling induces oncogene-induced senescence and senescence-associated secretory phenotype (SASP), which is characterized by enhanced production of various cytokines. BCR-ABL gene transduction confers senescent phenotype in vitro; however, the in vivo relevance of senescence has not been explored in this context. Transplantation of BCR-ABL-expressing hematopoietic stem/progenitor cells caused CML in mice with an increase in bone marrow BCR-ABL+CD41+CD150+ leukemic megakaryocyte-lineage (MgkL) cells, which exhibited enhanced senescence-associated β-galactosidase staining and increased expression of p16 and p21, key molecules that are crucially involved in senescence. Moreover, knockout of p16 and p21 genes reduced both BCR-ABL-induced abnormal megakaryopoiesis and the maintenance of CML cell leukemogenic capacity, as evidenced by attenuated leukemogenic capacity at secondary transplantation. The expression of transforming growth factor-β1 (TGF-β1), a representative SASP molecule, was enhanced in the leukemic MgkL cells, and TGF-β1 inhibition attenuated CML cell leukemogenic capacity both in vitro and in vivo. Furthermore, BCR-ABL-expressing MgkL cells displayed enhanced autophagic activity, and autophagy inhibition reduced bone marrow MgkL cell number and prolonged the survival of CML mice, which had transiently received the tyrosine kinase inhibitor, imatinib, earlier. Thus, BCR-ABL induced the expansion of senescent leukemic MgkL cells, which supported CML leukemogenesis by providing TGF-β1.

Evidence that knock down of GSK-3β in Chronic Myelogenous Leukemia cells augments IFN-γ-induced apoptosis

The role of interferon-gamma (IFN-γ) in Chronic Myelogenous/Myeloid Leukemia (CML) and in the treatment of CML remains unclear; specifically, the effect of IFN-γ on apoptosis. There is reported interplay between IFN-γ and glycogen synthase kinase-3 (GSK-3), a kinase which has been implicated in both cell death and, conversely, cell survival. Thus, we utilized the CML-derived HAP1 cell line and a mutant HAP1 GSK-3β knocked-down cell line (GSK-3β 31bp) to investigate whether GSK-3 modulates IFN-γ's action on CML cells. Significantly less GSK-3β 31bp cells, relative to HAP1 cells, were present after 48 h treatment with IFN-γ. IFN-γ treatment significantly decreased GSK-3β 31bp substrate adhesiveness (relative to HAP1 cells); an observation often correlated with cell death. Fluorescence microscopy revealed that IFN-γ induces a modest level of apoptosis in the HAP1 cells and that IFN-γ induced apoptosis is significantly enhanced in GSK-3β 31bp cells. Utilizing a complementary GSK-3β knocked-down cell line (8bp) we found, via flow cytometric analysis, that IFN-γ induced apoptosis is significantly enhanced in GSK-3β 8bp cells relative to HAP1 cells. Combined, our findings suggest that IFN-γ induces apoptosis of CML cells and that loss of GSK-3β significantly augments IFN-γ-induced apoptosis.

Intermolecular Interactions in Crystal Structures of Imatinib-Containing Compounds

Imatinib, one of the most used therapeutic agents to treat leukemia, is an inhibitor that specifically blocks the activity of tyrosine kinases. The molecule of imatinib is flexible and contains several functional groups able to take part in H-bonding and hydrophobic interactions. Analysis of molecular conformations for this drug was carried out using density functional theory calculations of rotation potentials along single bonds and by analyzing crystal structures of imatinib-containing compounds taken from the Cambridge Structural Database and the Protein Data Bank. Rotation along the N-C bond in the region of the amide group was found to be the reason for two relatively stable molecular conformations, an extended and a folded one. The role of various types of intermolecular interactions in stabilization of the particular molecular conformation was studied in terms of (i) the likelihood of H-bond formation, and (ii) their contribution to the Voronoi molecular surface. It is shown that experimentally observed hydrogen bonds are in accord with the likelihood of their formation. The number of H-bonds in ligand-receptor complexes surpasses that in imatinib salts due to the large number of donors and acceptors of H-bonding within the binding pocket of tyrosine kinases. Contribution of hydrophilic intermolecular interactions to the Voronoi molecular surface is similar for both conformations, while π...π stacking is more typical for the folded conformation of imatinib.

Metabolic Plasticity Is an Essential Requirement of Acquired Tyrosine Kinase Inhibitor Resistance in Chronic Myeloid Leukemia

Simple Summary

Tyrosine kinase inhibitors (TKIs), such as imatinib, have become the standard initial treatment of choice for chronic myeloid leukemia (CML) patients. However, one obstacle to face is that a significant proportion of patients presents poor response to TKIs, or acquires resistance resulting in disease relapses. Mutations in BCR-ABL1 protein are a well described mechanism of resistance but other not well established mechanisms outside BCR-ABL1 mutations are emerging as important in the acquisition of resistance. Abnormal metabolism of CML cells that acquire resistance to imatinib has been pointed out as a putative downstream key event, but deep studies aimed to unveil metabolic adaptations associated with acquired resistance are still lacking. Here, we perform an exhaustive study on metabolic reprogramming associated with acquired imatinib resistance and we identify metabolic vulnerabilities of CML imatinib resistant cells that could pave the way for new therapies targeting TKI failure.

Abstract

Tyrosine kinase inhibitors (TKIs) are currently the standard chemotherapeutic agents for the treatment of chronic myeloid leukemia (CML). However, due to TKI resistance acquisition in CML patients, identification of new vulnerabilities is urgently required for a sustained response to therapy. In this study, we have investigated metabolic reprogramming induced by TKIs independent of BCR-ABL1 alterations. Proteomics and metabolomics profiling of imatinib-resistant CML cells (ImaR) was performed. KU812 ImaR cells enhanced pentose phosphate pathway, glycogen synthesis, serine-glycine-one-carbon metabolism, proline synthesis and mitochondrial respiration compared with their respective syngeneic parental counterparts. Moreover, the fact that only 36% of the main carbon sources were utilized for mitochondrial respiration pointed to glycerol-phosphate shuttle as mainly contributors to mitochondrial respiration. In conclusion, CML cells that acquire TKIs resistance present a severe metabolic reprogramming associated with an increase in metabolic plasticity needed to overcome TKI-induced cell death. Moreover, this study unveils that KU812 Parental and ImaR cells viability can be targeted with metabolic inhibitors paving the way to propose novel and promising therapeutic opportunities to overcome TKI resistance in CML.

Ultra-small platinum nanoparticles on gold nanorods induced intracellular ROS fluctuation to drive megakaryocytic differentiation of leukemia cells

Chronic myeloid leukemia (CML) is a kind of hematological malignancy featured with retarded differentiation that is highly linked to the level of intracellular reactive oxygen species (ROS). In this work, ultra-small platinum nanoparticles deposited on gold nanorods (Au@Pt) were synthesized and applied on the CML cells. It was shown that Au@Pt had multienzyme-like activities that induced a fluctuation of the intracellular ROS level over the incubation time, depending on their temporal locations in the cells. The ROS fluctuation triggered cellular autophagy and enhanced the level of autophagic protein Beclin-1, which caused the degradation of fusion protein BCR-ABL, the key factor of retarded differentiation and led to the downregulation of phosphorylation of PI3K and AKT. These interactions together broke retarded differentiation and drove the CML cells to differentiate towards megakaryocytes, which is of great significance in enhancing leukemic cell apoptosis. Therefore, Au@Pt exhibited a novel function and promising therapeutic potential for the CML treatment.

NPM1 Mutated, BCR-ABL1 Positive Myeloid Neoplasms: Review of the Literature

Breakpoint cluster region - Abelson (BCR-ABL1) chimeric protein and mutated Nucleophosmin (NPM1) are often present in hematological cancers, but they rarely coexist in the same disease. Both anomalies are considered founder mutations that inhibit differentiation and apoptosis, but BCR-ABL1 could act as a secondary mutation conferring a proliferative advantage to a pre-neoplastic clone. The 2016 World Health Organization (WHO) classification lists the provisional acute myeloid leukemia (AML) with BCR-ABL1, which must be diagnosed differentially from the rare blast phase (BP) onset of chronic myeloid leukemia (CML), mainly because of the different therapeutic approach in the use of tyrosine kinase inhibitors (TKI). Here we review the BCR/ABL1 plus NPMc+ published cases since 1975 and describe a case from our institution in order to discuss the clinical and molecular features of this rare combination, and report the latest acquisition about an occurrence that could pertain either to the rare AML BCR-ABL1 positive or the even rarer CML-BP with mutated NPM1 at the onset. Differential diagnosis is based on careful analysis of genotypic and phenotypic features and anamnestic, clinical evolution, and background data. Therapeutic decisions must consider the broader clinical aspects, the comparatively mild effects of TKI therapy versus the great benefit that might bring to most of the patients, as may be incidentally demonstrated by our case history.

Clinical features and prognosis of duplex primary malignant neoplasms involving chronic myeloid leukemia

This study was to investigate clinical features and prognosis of duplex primary malignant neoplasms involving chronic myeloid leukemia (CML-DPMNs). Clinical data of thirteen CML-DPMN patients who were admitted to the First Hospital of Jilin University from May 2008 to December 2018 were collected and retrospectively analyzed. Female patients (9/13) were predominant in this cohort study. Nine patients were metachronous DPMNs (metachronous duplex primary malignant neoplasms involving chronic myeloid leukemia) with 5 years median interval time from primary malignancy to secondary malignancy. The other 4 patients were diagnosed as synchronous CML-DPMNs. Seven of the metachronous duplex primary malignant neoplasms involving chronic myeloid leukemia suffered from CML following many years of comprehensive anti-cancer therapy. Two of CML-MDPMN patients had invasive ductal carcinoma of breast after many years of treatment with imatinib. There was no difference between treatment-related CML group and non-treatment-related CML group in regard as the gender, age, white blood cell count, hemoglobin level, platelet count, and risk level. The median overall survival time of these thirteen patients with CML-DPMNs was not reached. In conclusion, female patients are more likely to suffer from the CML-DPMNs in the present article. Overall survival time of patients with DPMNs involving CML could be promising if timely and effective treatment therapy is adopted.

Tyrosine Kinase Inhibitors and the Relationship With Adherence, Costs, and Health Care Utilization in Commercially Insured Patients With Newly Diagnosed Chronic Myeloid Leukemia: A Retrospective Claims-Based Study

OBJECTIVE

To examine the association among tyrosine kinase inhibitor (TKI) out-of-pocket costs, adherence, and health care costs and utilization in a large group of commercially insured patients with chronic myeloid leukemia (CML).

MATERIALS AND METHODS

Patients with CML aged 18 to 64 years were identified using IBM MarketScan Commercial Database between April 1, 2011 and December 31, 2014. Patients were required to be continuously enrolled 3 months before and 12 months after TKI (imatinib, dasatinib, or nilotinib) initiation. TKI adherence is estimated using the proportion of days covered (PDC), defined as the percentage of the PDC by the prescription fill during the 12-month study period (adherent patients have PDC ≥80%). Health care cost differences between adherent and nonadherent patients were estimated using generalized linear models. Health care utilization was compared using negative binomial regression models. All models were controlled for potential confounding factors.

RESULTS

The study sample consisted of 863 patients, where 355 (41.1%) patients were classified as adherent. Over the study period, nonadherent patients incurred US$10,974 more in medical costs (P<0.001), and US$1663 more in non-TKI pharmacy costs (P<0.01). Adherent patients incurred US$28,184 more in TKI pharmacy costs (P<0.001) that resulted in US$18,305 more in overall total health care costs (P<0.001). Adherent patients, however, were estimated to be less likely to have all-cause hospitalizations (incidence rate ratio, 0.32; P<0.001), or CML-specific hospitalizations (incidence rate ratio, 0.31; P<0.01).

CONCLUSIONS

Patients with CML with better adherence experienced fewer hospitalizations, resulting in medical service cost savings. These lower medical costs, however, were more than offset by higher TKI medication costs observed during the first year of TKI therapy.

Chronic Myeloid Leukemia, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology

Chronic myeloid leukemia (CML) is defined by the presence of Philadelphia chromosome (Ph) which results from a reciprocal translocation between chromosomes 9 and 22 [t(9;22] that gives rise to a BCR-ABL1 fusion gene. CML occurs in 3 different phases (chronic, accelerated, and blast phase) and is usually diagnosed in the chronic phase. Tyrosine kinase inhibitor therapy is a highly effective first-line treatment option for all patients with newly diagnosed chronic phase CML. This manuscript discusses the recommendations outlined in the NCCN Guidelines for the diagnosis and management of patients with chronic phase CML.

Bcr-Abl Allosteric Inhibitors: Where We Are and Where We Are Going to

The fusion oncoprotein Bcr-Abl is an aberrant tyrosine kinase responsible for chronic myeloid leukemia and acute lymphoblastic leukemia. The auto-inhibition regulatory module observed in the progenitor kinase c-Abl is lost in the aberrant Bcr-Abl, because of the lack of the N-myristoylated cap able to bind the myristoyl binding pocket also conserved in the Bcr-Abl kinase domain. A way to overcome the occurrence of resistance phenomena frequently observed for Bcr-Abl orthosteric drugs is the rational design of allosteric ligands approaching the so-called myristoyl binding pocket. The discovery of these allosteric inhibitors although very difficult and extremely challenging, represents a valuable option to minimize drug resistance, mostly due to the occurrence of mutations more frequently affecting orthosteric pockets, and to enhance target selectivity with lower off-target effects. In this perspective, we will elucidate at a molecular level the structural bases behind the Bcr-Abl allosteric control and will show how artificial intelligence can be effective to drive the automated de novo design towards off-patent regions of the chemical space.

Design, synthesis, and biological evaluations of novel 3-amino-4-ethynyl indazole derivatives as Bcr-Abl kinase inhibitors with potent cellular antileukemic activity

Breakpoint cluster region-Abelson (Bcr-Abl) kinase is a key driver in the pathophysiology of chronic myelogenous leukemia (CML). Broadening the chemical diversity of Bcr-Abl kinase inhibitors with novel chemical entities possessing favorable target potency and cellular efficacy is a current medical demand for CML treatment. In this respect, a new series of ethynyl bearing 3-aminoindazole based Bcr-Abl inhibitors has been designed, synthesized, and biologically evaluated. The target compounds were designed based on introducing the key structural features of ponatinib, alkyne spacer and diarylamide, into the previously reported indazole II to improve its Bcr-Abl inhibitory activity and overcome its poor cellular potency. All target compounds elicited potent activity against Bcr-Abl^WT with sub-micromolar IC₅₀ values ranging 4.6-667 nM. In addition, certain derivatives exhibited promising potency over the clinically imatinib-resistant Bcr-Abl^T315I. Among the target molecules, compounds 9c, 9h and 10c stood as the most potent derivatives with IC₅₀ values of 15.4 nM, 4.6 nM, and 25.8 nM, respectively, against Bcr-Abl^WT. Interestingly, 9h showed 2 folds and 3.6 times superior potency to the lead indazole II and 10c, respectively, against Bcr-Abl^T315I. Molecular docking of 9h pointed out its possibility to be a type II kinase inhibitor. Furthermore, all compounds, except 9b, showed highly potent antiproliferative activity against the Bcr-Abl positive leukemia K562 cell (MTT assay) surpassing the modest activity of lead indazole II. Moreover, the most potent members 9h and 10c exerted potent antileukemic activity against NCI leukemia panel, particularly K562 cell (SRB assay) with GI₅₀ less than 10 nM, being superior to the FDA approved drug imatinib. Further biochemical hERG and cellular toxicity, phosphorylation assay, and NanoBRET target engagement of 9h underscored its merits as a promising candidate for CML therapy.

Influence of major BCR-ABL1 transcript subtype on outcome in patients with chronic myeloid leukemia in chronic phase treated frontline with nilotinib

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm characterized by the presence of BCR-ABL1 transcript as a result of reciprocal translocation between chromosome 9 and 22. The most common transcripts subtypes are e13a2 (b2a2) and e14a2 (b3a2). The prognostic impact of the type of BCR-ABL1 transcript has been the subject of controversies over time. In the imatinib era, several studies have suggested a deeper and faster response in patients expressing e14a2. However, the impact on response after first line therapy with a second-generation tyrosine kinase inhibitor, nilotinib, is unknown. We retrospectively evaluated 118 patients newly diagnosed with chronic phase CML and treated frontline with nilotinib inside or outside clinical trial in five French centers. Only patients expressing e14a2 or e13a2 transcripts alone were analyzed. At baseline, 55.3% expressed e14a2, 44.7% expressed e13a2. The median age was 51 years and median follow-up was 49 months. Relative risks of CML at diagnosis were similar according to the ELTS score (p = .87). Complete hematological response and complete cytogenetic response rates were similar among groups. Patients expressing e14a2 transcripts compared to e13a2 transcripts had deeper and faster molecular responses, when considering MMR (100% vs 84.1%, p = .007) with a median time of 6.7 and 17.1 months or MR^4.5 (100% vs 59.9%, p = .005) with a median time of 39.7 and 70.9 months, respectively. A sustained treatment free remission was observed in 10/10 patients with e14a2 versus 1/3 with e13a2 transcript (p = .04). In conclusion, even treated with nilotinib first line, patients with chronic phase CML expressing BCR-ABL1 e13a2 transcript have a lower rate of deep molecular responses.

Immunotherapy in Myeloproliferative Diseases

Myeloproliferative diseases, including myeloproliferative neoplasms (MPN) and myelodysplastic syndromes (MDS), are driven by genetic abnormalities and increased inflammatory signaling and are at high risk to transform into acute myeloid leukemia (AML). Myeloid-derived suppressor cells were reported to enhance leukemia immune escape by suppressing an effective anti-tumor immune response. MPNs are a potentially immunogenic disease as shown by their response to interferon-α treatment and allogeneic hematopoietic stem-cell transplantation (allo-HSCT). Novel immunotherapeutic approaches such as immune checkpoint inhibition, tumor vaccination, or cellular therapies using target-specific lymphocytes have so far not shown strong therapeutic efficacy. Potential reasons could be the pro-inflammatory and immunosuppressive microenvironment in the bone marrow of patients with MPN, driving tumor immune escape. In this review, we discuss the biology of MPNs with respect to the pro-inflammatory milieu in the bone marrow (BM) and potential immunotherapeutic approaches.

Management of a 75-Year-Old Lady with Refractory Chronic Myelogenous Leukemia

Chronic myelogenous leukemia (CML) is a hematopoietic disorder caused by the BCR/ABL gene or Philadelphia chromosome. The first Food and Drug Administration (FDA)-approved tyrosine kinase inhibitor for treatment of CML was imatinib in 2001. Since then, multiple therapies, such as nilotinib, dasatinib, bosutinib, and, more recently, ponatinib, have made their way as viable treatment options for first-line and secondary therapies. Most patients tend to respond to first-line treatment. Although there is a subset of patients who do not achieve complete molecular response with first line, newer options have proven beneficial. As we progress through therapies, there still remain some patients who do not adequately respond to current available therapies. The treatment options and guidelines become more difficult in such situations, not only with respect to cost but also patient quality of life and satisfaction. We discuss a 75-year-old white female with CML, who has had multiple therapies with hematological remission but has never achieved complete molecular remission, currently on bosutinib and tolerating it well.

Marrow fibrosis is an independent predictor of hematological toxicity of tyrosine kinase inhibitors for the treatment of chronic myeloid leukemia

Hematological toxicity is a common adverse effect of tyrosine kinase inhibitors (TKIs) for the treatment of chronic myeloid leukemia (CML). We retrospectively investigated the incidence of hematological toxicity after TKI administration in 143 CML patients and parameters associated with hematological toxicity. Severe hematological toxicity (grade 3-4) existed in 26 (18.2%) patients. Marrow fibrosis (MF), age, Sokal score, and spleen enlargement were associated with severe hematological toxicity. Further multivariate analysis showed that only MF was an independent predictor. Complete cytogenetic response(CCyR) rates and major molecular response (MMR) rates with grade 3-4 hematological toxicity were 42.3% and 26.9%, respectively, significantly lower than patients with grade 1-2 and without hematological toxicity (p = .032 for CCyR and p = .044 for MMR). Similar results were observed regarding progression-free survival (PFS) and overall survival (OS) (p = .011 for PFS and p = .037 for OS). This study indicated that MF was an independent predictor of severe hematological toxicity of TKIs.

Tyrosine Kinase Inhibition: a New Perspective in the Fight against HIV

PURPOSE OF REVIEW

HIV-1 infection is incurable due to the existence of latent reservoirs that persist in the face of cART. In this review, we describe the existence of multiple HIV-1 reservoirs, the mechanisms that support their persistence, and the potential use of tyrosine kinase inhibitors (TKIs) to block several pathogenic processes secondary to HIV-1 infection.

RECENT FINDINGS

Dasatinib interferes in vitro with HIV-1 persistence by two independent mechanisms. First, dasatinib blocks infection and potential expansion of the latent reservoir by interfering with the inactivating phosphorylation of SAMHD1. Secondly, dasatinib inhibits the homeostatic proliferation induced by γc-cytokines. Since homeostatic proliferation is thought to be the main mechanism behind the maintenance of the latent reservoir, we propose that blocking this process will gradually reduce the size of the reservoir. TKIs together with cART will interfere with HIV-1 latent reservoir persistence, favoring the prospect for viral eradication.

CRISPR/CAS9-mediated knockout of Abi1 inhibits p185Bcr-Abl-induced leukemogenesis and signal transduction to ERK and PI3K/Akt pathways

Background

Abl interactor 1 (Abi1) is a downstream target of Abl tyrosine kinases and a component of the WAVE regulatory complex (WRC) that plays an important role in regulating actin cytoskeleton remodeling and membrane receptor signaling. While studies using short hairpin RNA (shRNA) have suggested that Abi1 plays a critical role in Bcr-Abl-induced leukemogenesis, the mechanism involved is not clear.

Methods

In this study, we knocked out Abi1 expression in p185^Bcr-Abl-transformed hematopoietic cells using CRISPR/Cas9-mediated gene editing technology. The effects of Abi1 deficiency on actin cytoskeleton remodeling, the Bcr-Abl signaling, IL-3 independent growth, and SDF-induced chemotaxis in these cells were examined by various in vitro assays. The leukemogenic activity of these cells was evaluated by a syngeneic mouse transplantation model.

Results

We show here that Abi1 deficiency reduced the IL3-independent growth and SDF-1α-mediated chemotaxis in p185^Bcr-Abl-transformed hematopoietic cells and inhibited Bcr-Abl-induced abnormal actin remodeling. Depletion of Abi1 also impaired the Bcr-Abl signaling to the ERK and PI3 kinase/Akt pathways. Remarkably, the p185^Bcr-Abl-transformed cells with Abi1 deficiency lost their ability to develop leukemia in syngeneic mice. Even though these cells developed drug tolerance in vitro after prolonged selection with imatinib as their parental cells, the imatinib-tolerant cells remain incapable of leukemogenesis in vivo.

Conclusions

Together, this study highlights an essential role of Abi1 in Bcr-Abl-induced leukemogenesis and provides a model system for dissecting the Abi1 signaling in Bcr-Abl-positive leukemia.

TARGET: a survey of real-world management of chronic myeloid leukaemia across 33 countries

Despite the availability of guidelines for the management of chronic myeloid leukaemia (CML), various issues may prevent their successful implementation. The TARGET survey examined real-world management of CML patients compared with international recommendations. This online survey was completed in 2017. Results were discussed by a Steering Committee (SC) of eight international haematologists, challenges were identified and practical solutions developed. Of the 1008 haematologists invited (33 countries), 614 completed the survey. Gaps regarding treatment efficacy and molecular monitoring were identified. Half of the physicians did not perform three-monthly testing of during the initial 12 months of treatment, citing cost as the major barrier, although they know it should be done. Treatment-free remission was not considered a primary treatment goal or as a priority factor influencing treatment decisions. European Leukemia Net guidelines interpretation was generally acceptable, but awareness regarding management of persistent adverse events was poor. Practical solutions proposed by the SC were mostly focused on enhancing physician education and awareness, or encouraging hospitals to work with the government, in order to improve the quality of BCR-ABL testing. Gaps in current CML management were identified compared with international recommendations, which the proposed practical solutions would help to address.

Leukemic Involvement in the Thorax

Leukemias are malignancies in which abnormal white blood cells are produced in the bone marrow, resulting in compromise of normal bone marrow hematopoiesis and subsequent cytopenias. Leukemias are classified as myeloid or lymphoid depending on the type of abnormal cells produced and as acute or chronic according to cellular maturity. The four major types of leukemia are acute myeloid leukemia, chronic myeloid leukemia, acute lymphoblastic leukemia, and chronic lymphocytic leukemia. Clinical manifestations are due to either bone marrow suppression (anemia, thrombocytopenia, or neutropenia) or leukemic organ infiltration. Imaging manifestations of leukemia in the thorax are myriad. While lymphadenopathy is the most common manifestation of intrathoracic leukemia, leukemia may also involve the lungs, pleura, heart, and bones and soft tissues. Myeloid sarcomas occur in 5%-7% of patients with acute myeloid leukemia and represent masses of myeloid blast cells in an extramedullary location. ^©RSNA, 2019.

C/EBPβ is a critical mediator of IFN-α-induced exhaustion of chronic myeloid leukemia stem cells

Even in the era of ABL tyrosine kinase inhibitors, eradication of chronic myeloid leukemia (CML) stem cells is necessary for complete cure of the disease. Interferon-α (IFN-α) has long been used for the treatment of chronic-phase CML, but its mechanisms of action against CML stem cells remain unclear. We found that IFN-α upregulated CCAAT/enhancer binding protein β (C/EBPβ) in BCR-ABL-expressing mouse cells by activating STAT1 and STAT5, which were recruited to a newly identified 3' distal enhancer of Cebpb that contains tandemly aligned IFN-γ-activated site elements. Suppression or deletion of the IFN-γ-activated site elements abrogated IFN-α-dependent upregulation of C/EBPβ. IFN-α induced differentiation and exhaustion of CML stem cells, both in vitro and in vivo, in a C/EBPβ-dependent manner. In addition, IFN-α upregulated C/EBPβ and induced exhaustion of lineage^- CD34⁺ cells from CML patients. Collectively, these results clearly indicate that C/EBPβ is a critical mediator of IFN-α-induced differentiation and exhaustion of CML stem cells.

Pseudolaric acid B induces mitotic arrest and apoptosis in both imatinib-sensitive and -resistant chronic myeloid leukaemia cells

The selective BCR-ABL tyrosine kinase inhibitor imatinib is one of the first-line therapies in the management of chronic myeloid leukaemia (CML). However, acquired resistance to this inhibitor, which is especially conferred by the T315I point mutation in BCR-ABL, impedes the efficacy of imatinib therapy. Therefore, the discovery and development of novel agents to overcome imatinib resistance is urgently needed. Pseudolaric acid B (PAB), a small molecule isolated from the traditional Chinese medicine Cortex pseudolaricis, has been reported to be a potential candidate for immune disorders and cancer treatment. However, its effects on CML and the involved molecular mechanism have not been reported. In the current study, by performing both in vitro and in vivo experiments in CML cells, we showed that PAB blocked the cell cycle at G₂/M phase and subsequently activated the caspase pathway, cleaved the BCR-ABL protein and inhibited the BCR-ABL downstream pathways, ultimately leading to cell proliferation inhibition, cytotoxicity and apoptosis. These events were observed in both imatinib-sensitive and imatinib-insensitive CML cell lines. Moreover, PAB decreased the viability of primary blood mononuclear cells from CML patients and induced apoptosis in these cells. Our findings suggest that PAB could be used as a novel agent to sensitize imatinib-resistant CML.

Influence of proton pump inhibitors and H2-receptor antagonists on the efficacy and safety of dasatinib in chronic myeloid leukemia patients

We evaluated the effect of proton pump inhibitors (PPIs) and H2-receptor antagonists (H2RAs) on the efficacy and safety of dasatinib for chronic-phase chronic myeloid leukemia (CP-CML). Retrospective analyses were performed for patients with CP-CML who received dasatinib at seven hospitals between April 2009 and December 2016. Seventy-three patients were identified, 16 of whom received PPIs or H2RAs concurrently with dasatinib. Major molecular response at 12 months was observed in 13 of 13 patients (100%) with concurrent PPIs or H2RAs (combination group), and in 23 of 51 patients (45.1%) who received only dasatinib (dasatinib-alone group; P < 0.001). Deep molecular response at 12 months was observed in four of six patients (66.7%) in the combination group, and seven of 38 patients (18.4%) in the dasatinib-alone group (P = 0.027). Dasatinib chemotherapy was stopped after 18 months for 25 patients (43.9%) from the dasatinib-alone group, but for none from the combination group. Combination treatment with PPIs or H2RAs did not reduce the efficacy of dasatinib. PPIs and H2RAs reduce the incidence of dasatinib discontinuation due to adverse events and increase the efficacy of dasatinib chemotherapy for patients.

Bone marrow niche crosses paths with BMPs: a road to protection and persistence in CML

Chronic myeloid leukaemia (CML) is a paradigm of precision medicine, being one of the first cancers to be treated with targeted therapy. This has revolutionised CML therapy and patient outcome, with high survival rates. However, this now means an ever-increasing number of patients are living with the disease on life-long tyrosine kinase inhibitor (TKI) therapy, with most patients anticipated to have near normal life expectancy. Unfortunately, in a significant number of patients, TKIs are not curative. This low-level disease persistence suggests that despite a molecularly targeted therapeutic approach, there are BCR-ABL1-independent mechanisms exploited to sustain the survival of a small cell population of leukaemic stem cells (LSCs). In CML, LSCs display many features akin to haemopoietic stem cells, namely quiescence, self-renewal and the ability to produce mature progeny, this all occurs through intrinsic and extrinsic signals within the specialised microenvironment of the bone marrow (BM) niche. One important avenue of investigation in CML is how the disease highjacks the BM, thereby remodelling this microenvironment to create a niche, which enables LSC persistence and resistance to TKI treatment. In this review, we explore how changes in growth factor levels, in particular, the bone morphogenetic proteins (BMPs) and pro-inflammatory cytokines, impact on cell behaviour, extracellular matrix deposition and bone remodelling in CML. We also discuss the challenges in targeting LSCs and the potential of dual targeting using combination therapies against BMP receptors and BCR-ABL1.

Validation of the EUTOS Long-Term Survival Score in Chinese Chronic Myeloid Leukemia Patients Treated with Imatinib: A Multicenter Real-World Study

Purpose

To validate the clinical efficacy of the recently developed EUTOS long-term survival (ELTS) score in a real-world setting.

Patients and Methods

A total of 479 chronic myeloid leukemia (CML) patients treated with frontline imatinib between January 2010 and December 2017 were enrolled in this retrospective study. The ELTS score was evaluated on the end-points including complete cytogenetic response (CCyR), progression-free survival (PFS), overall survival (OS) and CML-related death, and the efficiency of the ELTS score was further compared with the historical Sokal, Hasford, EUTOS scores.

Results

With a median follow-up of 69 months (range, 9–112 months), 462 evaluable patients were stratified into the ELTS low-risk (n = 230), ELTS intermediate-risk (n = 168) and ELTS high-risk (n = 64) groups. For the regular assessment indicators like CCyR, PFS and OS, the ELTS scoring system could effectively identify the corresponding risk groups, similarly with the results provided by previous scoring systems. With respect to the CML-related death, the ELTS score could accurately identify a high-risk group with a significantly higher risk of dying of CML, and the 5-year cumulative incidence occurred in the ELTS high-, intermediate-, and low-risk groups was 11% (95% CI: 3–19%), 5% (95% CI: 1–9%) and 2% (95% CI: 0–4%), respectively. Most notably, the ELTS score outperformed the Sokal, Hasford and EUTOS scores without statistical difference among different risk groups.

Conclusion

The ELTS score could effectively predict the prognosis of imatinib-treated CML patients in real-life settings.

Randomized study of imatinib for chronic myeloid leukemia: comparing standard dose escalation with aggressive escalation

In 2007, we conducted a prospective randomized study to compare an aggressive dose escalation (group B, n = 123) with the standard dose escalation proposed by European LeukemiaNet (group A, n = 122). In group B, if patients did not achieve a complete cytogenetic response (CCyR) at 3 months or did not achieve a major molecular response (MR3) at 6 months, imatinib was increased to 600 mg. At 6 months CCyR was achieved in 69.4% and 78.7% of patients in groups A and B, respectively. The rate of MR3 at 12 months and 24 months were similar in group A (52.1% and 70.0%) and group B (58.7% and 68.3%). The cumulative incidence of withdrawal by failure without accelerated/blast phase was higher in group A than in group B (9.2% vs 2.5% at 24 months). At 3 and 6 months, the protocol called for the imatinib dose to increase to 600 mg in 90 patients (74.4%) in group B. Among the 42 patients who received increased dose according to the protocol, 25 (60.0%) achieved MR3 at 12 months, whereas only 14 (35.0%) of 40 patients who did not receive an increased dose achieved MR3 (P < .05). The number of patients who withdrew from this study was similar (group A, 20%; group B, 21%). The early aggressive dose escalation failed to produce a better molecular response at 12 months. However, for patients who tolerate imatinib well, but show inadequate response at an early time point, aggressive dose escalation may contribute to achieving a better outcome. This study was registered at http://www.umin.ac.jp/ctr/ as #R000000965.