Comparison of Dasatinib, Nilotinib, and Imatinib in the Treatment of Chronic Myeloid Leukemia

Oxidative Stress and Chronic Myeloid Leukemia: A Balance between ROS-Mediated Pro- and Anti-Apoptotic Effects of Tyrosine Kinase Inhibitors

The balanced reciprocal translocation t (9; 22) (q34; q11) and the BCR-ABL fusion gene, which produce p210 bcr-abl protein production with high tyrosine kinase activity, are characteristics of chronic myeloid leukemia, a myeloproliferative neoplasm. This aberrant protein affects several signaling pathways connected to both apoptosis and cell proliferation. It has been demonstrated that tyrosine kinase inhibitor treatment in chronic myeloid leukemia acts by inducing oxidative stress and, depending on its level, can activate signaling pathways responsible for either apoptosis or survival in leukemic cells. Additionally, oxidative stress and reactive oxygen species generation also mediate apoptosis through genomic activation. Furthermore, it was shown that oxidative stress has a role in both BCR-ABL-independent and BCR-ABL-dependent resistance pathways to tyrosine kinases, while patients with chronic myeloid leukemia were found to have a significantly reduced antioxidant level. The ideal environment for tyrosine kinase inhibitor therapy is produced by a favorable oxidative status. We discuss the latest studies that aim to manipulate the redox system to alter the apoptosis of cancerous cells.

Potential Approaches Versus Approved or Developing Chronic Myeloid Leukemia Therapy

Tyrosine kinase inhibitors (TKIs) have revolutionized the treatment of patients with chronic myeloid leukemia (CML). However, continued use of these inhibitors has contributed to the increase in clinical resistance and the persistence of resistant leukemic stem cells (LSCs). So, there is an urgent need to introduce additional targeted and selective therapies to eradicate quiescent LSCs, and to avoid the relapse and disease progression. Here, we focused on emerging BCR-ABL targeted and non-BCR-ABL targeted drugs employed in clinical trials and on alternative CML treatments, including antioxidants, oncolytic virus, engineered exosomes, and natural products obtained from marine organisms that could pave the way for new therapeutic approaches for CML patients.

Chronic myeloid leukemia stem cells: targeting therapeutic implications

Chronic myeloid leukemia (CML) is a clonal myeloproliferative neoplasm driven by BCR-ABL1 oncoprotein, which plays a pivotal role in CML pathology, diagnosis, and treatment as confirmed by the success of tyrosine kinase inhibitor (TKI) therapy. Despite advances in the development of more potent tyrosine kinase inhibitors, some mechanisms particularly in terms of CML leukemic stem cell (CML LSC) lead to intrinsic or acquired therapy resistance, relapse, and disease progression. In fact, the maintenance CML LSCs in patients who are resistance to TKI therapy indicates the role of CML LSCs in resistance to therapy through survival mechanisms that are not completely dependent on BCR-ABL activity. Targeting therapeutic approaches aim to eradicate CML LSCs through characterization and targeting genetic alteration and molecular pathways involving in CML LSC survival in a favorable leukemic microenvironment and resistance to apoptosis, with the hope of providing a functional cure. In other words, it is possible to develop the combination therapy of TKs with drugs targeting genes or molecules more specifically, which is required for survival mechanisms of CML LSCs, while sparing normal HSCs for clinical benefits along with TKIs.

The contrast agent 2,3,5-triiodobenzoic acid (TIBA) induces cell death in tumor cells through the generation of reactive oxygen species

The 2,3,5-triiodobenzoic acid (TIBA) is an iodine contrast agent used for visualization of tissue in X-ray techniques. However, TIBA induces physiological complications like increase in oxygen reactive species (ROS), and consequently, contrast-induced nephropathies. TIBA's antitumor activity was demonstrated in lung cancer, but the subcellular mechanisms involving its activity in tumor cells are still unknown. Thus, the objective of this work was evaluate whether the anti-tumor activity of TIBA involves ROS increase, in tumor lines of non-small cell lung cancer (H460), chronic myeloid leukemia (K562), and its cytotoxicity in normal renal epithelial (VERO). The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide) assay was used for evaluation of cell viability, the H₂DCFDA (cell-permeant 2',7'-dichlorodihydrofluorescein diacetate) fluorescent probe to evaluate ROS induction, cell cycle analysis was performed using flow cytometry to measure cell death, and immunofluorescence with annexin/7-AAD (7-amino-actinomycin D), to assess the association of cell death with the ROS generation. TIBA decreases cell viability in a dose-dependent manner for the H460 and K562. However, VERO cells showed less response to the drug, with 70% viable cells after 72 h of treatment in the highest concentration of the drug. While the tumor cells with only 20% viable cells. Besides, tumor cells exhibited higher DNA fragmentation, compared to the renal line (VERO with 5% of fragmented DNA, H460 with 26%, and 56% in K562). Finally, TIBA-induced ROS increase and apoptosis in all lines, which is significantly decreased after treatment with the antioxidant N-acetyl-cysteine (NAC). These data demonstrate the relationship between the increased cellular oxidative stress and the anti-tumor action of the TIBA.

A Case Report of Multiple Capillary Hemangioma in a Chronic Myeloid Leukemia Patient Taking Tyrosine Kinase Inhibitors

A capillary hemangioma is a vascular tumor with small capillary sized vascular channel. Multiple capillary hemangioma in relation with drugs have been rarely reported. Here in, we report a case of multiple capillary hemangioma in patient diagnosed with chronic myeloid leukemia who received tyrosine kinase inhibitors (TKIs). Histopathological findings have shown capillary proliferation in the upper dermis, which is consistent with capillary hemangioma. Since TKIs can paradoxically activate the MEK/ERK pathway which is required for angiogenesis, we presumed that the lesions as the cutaneous side effects of TKIs.

Targeting Abnormal Hematopoietic Stem Cells in Chronic Myeloid Leukemia and Philadelphia Chromosome-Negative Classical Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPNs) are unique hematopoietic stem cell disorders sharing mutations that constitutively activate the signal-transduction pathways involved in haematopoiesis. They are characterized by stem cell-derived clonal myeloproliferation. The key MPNs comprise chronic myeloid leukemia (CML), polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). CML is defined by the presence of the Philadelphia (Ph) chromosome and BCR-ABL1 fusion gene. Despite effective cytoreductive agents and targeted therapy, complete CML/MPN stem cell eradication is rarely achieved. In this review article, we discuss the novel agents and combination therapy that can potentially abnormal hematopoietic stem cells in CML and MPNs and the CML/MPN stem cell-sustaining bone marrow microenvironment.

Chronic Myelogenous Leukemia Diagnosed in the Setting of Untreated Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma

Chronic myeloid leukemia (CML) is rarely reported to occur in treated chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). In this article, we report a woman in her 70s, diagnosed with CLL/SLL in 2000, untreated, who subsequently presented 12 years later with de novo CML, BCR-ABL1+. Her IGHV mutated CLL/SLL based on the initial sample in our laboratory showed homozygous and heterozygous 13q14.3 deletions, whereas her CML, at presentation, showed a 46,XX,t(9;22)(q34;q11.2)[7]/46,XX[18] karyotype with a p190 BCR-ABL1 transcript. The tumor burden of each clone varied with treatment, including when treated with dasatinib, used to target both clones. In addition, the cytogenetic abnormalities evolved over time and treatments and included acquisition of an extra chromosome 8 in the CML clone and a novel K1992T ATM missense mutation (47% allele frequency) in the CLL/SLL clone. The patient's last bone marrow biopsy, 5 years after her CML diagnosis and 17 years after the CLL/SLL diagnosis, showed residual CML with extensive involvement by CLL/SLL (80%). Cytogenetic studies showed a 46,XX karyotype, while FISH identified 13q14.3 deletion and the BCR-ABL1 translocation in the CLL/SLL and CML clones, respectively. To date, this is the fourth case of concurrent CML, BCR-ABL1+ arising in untreated CLL/SLL. Here we show dynamic variation in the size of the 2 clonal processes reflecting the variable responsiveness to specific therapies. In addition to the unusual BCR-ABL1+ p190 transcript in the patient's CML, a novel ATM K1992T mutation was identified in the CLL/SLL population.

Identification of circadian clock modulators from existing drugs

Chronic circadian disruption due to shift work or frequent travel across time zones leads to jet‐lag and an increased risk of diabetes, cardiovascular disease, and cancer. The development of new pharmaceuticals to treat circadian disorders, however, is costly and hugely time‐consuming. We therefore performed a high‐throughput chemical screen of existing drugs for circadian clock modulators in human U2OS cells, with the aim of repurposing known bioactive compounds. Approximately 5% of the drugs screened altered circadian period, including the period‐shortening compound dehydroepiandrosterone (DHEA; also known as prasterone). DHEA is one of the most abundant circulating steroid hormones in humans and is available as a dietary supplement in the USA. Dietary administration of DHEA to mice shortened free‐running circadian period and accelerated re‐entrainment to advanced light–dark (LD) cycles, thereby reducing jet‐lag. Our drug screen also revealed the involvement of tyrosine kinases, ABL1 and ABL2, and the BCR serine/threonine kinase in regulating circadian period. Thus, drug repurposing is a useful approach to identify new circadian clock modulators and potential therapies for circadian disorders.

Genie in a bottle: controlled release helps tame natural polypharmacology?

Ability to faithfully report drug-target interactions constitutes a major critical parameter in preclinical/clinical settings. Yet the assessment of target engagement remains challenging, particularly for promiscuous and/or polypharmacologic ligands. Drawing from our improved insights into native electrophile signaling and emerging technologies that profile and interrogate these non-enzyme-assisted signaling subsystems, we posit that 'trained' polypharmocologic covalent inhibitors can be designed. Accumulating evidence indicates that electrophile-modified states at fractional occupancy can alter cell fate. Thus, by understanding sensing preferences and ligandable regions favored by the natural electrophilic signals at individual protein-ligand resolution, we can better evaluate target engagement and develop a function-guided understanding of polypharmacology.

The second generation tyrosine kinase inhibitor dasatinib induced eryptosis in human erythrocytes-An in vitro study

Dasatinib, a new tyrosine kinase inhibitor, is used clinically to kill chronic myelogenous leukemia and acute lymphoblastic leukemia through apoptosis. Obviously, anemia is developed in many patients receiving dasatinib for treatment. Until now, the mechanism for the cytotoxic effects of dasatinib in human erythrocytes is not fully understood. As many tyrosine kinases are found in human erythrocytes, it is therefore logical to hypothesize that dasatinib is able to induce apoptosis (or eryptosis) in human erythrocytes. True to our expectation, dasatinib inhibited tyrosine kinase and induced eryptosis in human erythrocytes with early denature of esterase, cell shrinkage, loss of membrane integrity with inside-out phosphatidylserine, increase in the cytosolic Ca²⁺ ion concentration ([Ca²⁺]i), caspase-3 activation and change in cellular redox state. Mechanistically, the rise of [Ca²⁺]i seems to be a key mediator in the dasatinib-mediated eryptosis because depletion of external Ca²⁺ could suppress the eryptotic effects. Also, dasatinib was able to reduce membrane fluidity in human RBCs. For the direct action on membrane, dasatinib permeabilized RBC ghosts in a way similar to digitonin. Taken together, we report here for the first time that dasatinib inhibited tyrosine kinase and induced eryptosis in human erythrocytes through Ca²⁺ loading and membrane permeabilization.

Clinical Pharmacokinetics and Pharmacodynamics of Bosutinib

Chronic myeloid leukemia (CML) is a clonal myeloproliferative stem cell disorder. Bosutinib is an oral, once-daily SRC/ABL tyrosine kinase inhibitor with very potent inhibitory activity. Bosutinib is effective against all phases of intolerant or resistant Philadelphia chromosome-positive CML that do not harbor the T315I or V299LABL kinase domain mutations. Peak plasma concentrations of bosutinib occur at 4-6 h following oral administration, and dose-proportional increases in exposure are observed at doses ranging from 200 to 800 mg. Absorption of bosutinib increases with food. Bosutinib is distributed extensively into the tissues. It is highly plasma protein bound (94 %) and is primarily metabolized in the liver by cytochrome P450 3A4. Bosutinib is well tolerated overall and has a unique but manageable toxicity profile. This article provides a review of the available clinical pharmacokinetic, pharmacodynamic, and drug-drug interaction data on bosutinib in healthy subjects, patients with CML, and special populations.

Hematology oncology practice in the Asia-Pacific APHCON survey results from the 6th international hematologic malignancies conference: bridging the gap 2015, Beijing, China

This report serves as a snapshot of the state-of-knowledge in the Asia Pacific (APAC) Hematology Oncology community, and establishes a baseline for longitudinal investigations to follow changes in best practices over time. The objective of this study was to understand the approach to hematologic diseases, common standards of care and best practices, issues that remain controversial or debated, and educational or resource gaps that warrant attention. We used mobile application to disseminate and distribute questionnaires to delegates during the 6th international hematologic malignancies conference hosted by the APAC Hematology Consortium at Beijing, China. User responses were collected in an anonymous fashion. We report survey results in two ways: the overall responses, and responses as stratified between Chinese physicians and "Other" represented nationalities. Overall geographical concordance in survey responses was positive and strong. Perhaps more interesting than instances of absolute agreement, these data provide a unique opportunity to identify topics in which physician knowledge or opinions diverge. We assigned questions from all modules to broad categories of: patient information; diagnosis; treatment preference; transplantation; and general knowledge/opinion. On average, we observed a geographic difference of 15% for any particular answer choice, and this was fairly constant across survey modules. These results reveal utility and need for widespread and ongoing initiatives to assess knowledge and provide evidence-based education in real time. The data will be made more valuable by longitudinal participation, such that we can monitor changes in the state of the art over time.

Distinct Dasatinib-Induced Mechanisms of Apoptotic Response and Exosome Release in Imatinib-Resistant Human Chronic Myeloid Leukemia Cells

Although dasatinib is effective in most imatinib mesylate (IMT)-resistant chronic myeloid leukemia (CML) patients, the underlying mechanism of its effectiveness in eliminating imatinib-resistant cells is only partially understood. This study investigated the effects of dasatinib on signaling mechanisms driving-resistance in imatinib-resistant CML cell line K562 (K562R^IMT). Compared with K562 control cells, exsomal release, the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/ mammalian target of rapamycin (mTOR) signaling and autophagic activity were increased significantly in K562R^IMT cells and mTOR-independent beclin-1/Vps34 signaling was shown to be involved in exosomal release in these cells. We found that Notch1 activation-mediated reduction of phosphatase and tensin homolog (PTEN) was responsible for the increased Akt/mTOR activities in K562R^IMT cells and treatment with Notch1 γ-secretase inhibitor prevented activation of Akt/mTOR. In addition, suppression of mTOR activity by rapamycin decreased the level of activity of p70S6K, induced upregulation of p53 and caspase 3, and led to increase of apoptosis in K562R^IMT cells. Inhibition of autophagy by spautin-1 or beclin-1 knockdown decreased exosomal release, but did not affect apoptosis in K562R^IMT cells. In summary, in K562R^IMT cells dasatinib promoted apoptosis through downregulation of Akt/mTOR activities, while preventing exosomal release and inhibiting autophagy by downregulating expression of beclin-1 and Vps34. Our findings reveal distinct dasatinib-induced mechanisms of apoptotic response and exosomal release in imatinib-resistant CML cells.