New insights into the pathophysiology of chronic myeloid leukemia and imatinib resistance

Physiologically based pharmacokinetic modeling of imatinib and N-desmethyl imatinib for drug-drug interaction predictions

The first-generation tyrosine kinase inhibitor imatinib has revolutionized the development of targeted cancer therapy and remains among the frontline treatments, for example, against chronic myeloid leukemia. As a substrate of cytochrome P450 (CYP) 2C8, CYP3A4, and various transporters, imatinib is highly susceptible to drug-drug interactions (DDIs) when co-administered with corresponding perpetrator drugs. Additionally, imatinib and its main metabolite N-desmethyl imatinib (NDMI) act as inhibitors of CYP2C8, CYP2D6, and CYP3A4 affecting their own metabolism as well as the exposure of co-medications. This work presents the development of a parent-metabolite whole-body physiologically based pharmacokinetic (PBPK) model for imatinib and NDMI used for the investigation and prediction of different DDI scenarios centered around imatinib as both a victim and perpetrator drug. Model development was performed in PK-Sim® using a total of 60 plasma concentration-time profiles of imatinib and NDMI in healthy subjects and cancer patients. Metabolism of both compounds was integrated via CYP2C8 and CYP3A4, with imatinib additionally transported via P-glycoprotein. The subsequently developed DDI network demonstrated good predictive performance. DDIs involving imatinib and NDMI were simulated with perpetrator drugs rifampicin, ketoconazole, and gemfibrozil as well as victim drugs simvastatin and metoprolol. Overall, 12/12 predicted DDI area under the curve determined between first and last plasma concentration measurements (AUClast) ratios and 12/12 predicted DDI maximum plasma concentration (Cmax) ratios were within twofold of the respective observed ratios. Potential applications of the final model include model-informed drug development or the support of model-informed precision dosing.

New Derivatives of 1-(3-Methyl-1-Benzofuran-2-yl)Ethan-1-one: Synthesis and Preliminary Studies of Biological Activity

A set of nine derivatives, including five brominated compounds, was synthesized and the structures of these novel compounds were confirmed using 1H and 13C NMR as well as ESI MS spectra. These compounds were tested on four different cancer cell lines, chronic myelogenous leukemia (K562), prostate cancer (PC3), colon cancer (SW620), human kidney cancer (Caki 1), and on healthy human keratocytes (HaCaT). MTT results reveal that two newly developed derivatives (6 and 8) exhibit selective action towards K562 cells and no toxic effect in HaCat cells. The biological activity of these two most promising compounds was evaluated by trypan blue assay, reactive oxygen species generation, and IL-6 secretion. To investigate the proapoptotic activity of selected compounds, the two following types of tests were performed: Annexin V Apoptosis Detection Kit I and Caspase-Glo 3/7 assay. The studies of the mechanism showed that both compounds have pro-oxidative effects and increase reactive oxygen species in cancer cells, especially at 12 h incubation. Through the Caspase-Glo 3/7 assay, the proapoptotic properties of both compounds were confirmed. The Annexin V-FITC test revealed that compounds 6 and 8 induce apoptosis in K562 cells. Both compounds inhibit the release of proinflammatory interleukin 6 (IL-6) in K562 cells. Additionally, all compounds were screened for their antibacterial activities using standard and clinical strains. Within the studied group, compound 7 showed moderate activity towards Gram-positive strains in antimicrobial studies, with MIC values ranging from 16 to 64 µg/mL.

Methyl-Thiol-Bridged Oxadiazole and Triazole Heterocycles as Inhibitors of NF-κB in Chronic Myelogenous Leukemia Cells

Nuclear factor kappa beta (NF-κB) is a transcriptional factor that plays a crucial role in regulating cancer cell proliferation. Therefore, the inhibition of NF-κB activity by small molecules may be beneficial in cancer therapy. In this report, methyl-thiol-bridged oxadiazole and triazole heterocycles were synthesized via click chemistry and it was observed that the lead structure, 2-(((1-(3,4-dichlorophenyl)-1H-1,2,3-triazol-4-yl)methyl)thio)-5-(4-methoxybenzyl)-1,3,4-oxadiazole (4c), reduced the viability of MCF-7 cells with an IC₅₀ value of 7.4 µM. Compound 4c also caused concentration-dependent loss of cell viability in chronic myelogenous leukemia (CML) cells. Furthermore, compound 4c inhibited the activation of NF-κB in human CML cells as observed by nuclear translocation and DNA binding assays. Functionally, compound 4c produced PARP cleavage and also suppressed expression of Bcl-2/xl, MMP-9, COX-2, survivin, as well as VEGF, resulting in apoptosis of CML cells. Moreover, ChIP assay showed that compound 4c decreased the binding of COX-2 to the p65 gene promoter. Detailed in silico analysis also indicated that compound 4c targeted NF-κB in CML cells. In conclusion, a novel structure bearing both triazole and oxadiazole moieties has been identified that can target NF-κB in CML cells and may constitute a potential novel drug candidate.

Brassinin Induces Apoptosis, Autophagy, and Paraptosis via MAPK Signaling Pathway Activation in Chronic Myelogenous Leukemia Cells

Brassinin (BSN), a potent phytoalexin found in cruciferous vegetables, has been found to exhibit diverse anti-neoplastic effects on different cancers. However, the impact of BSN on chronic myelogenous leukemia (CML) cells and the possible mode of its actions have not been described earlier. We investigated the anti-cytotoxic effects of BSN on the KBM5, KCL22, K562, and LAMA84 CML cells and its underlying mechanisms of action in inducing programmed cell death. We noted that BSN could induce apoptosis, autophagy, and paraptosis in CML cells. BSN induced PARP cleavage, subG1 peak increase, and early apoptosis. The potential action of BSN on autophagy activation was confirmed by an LC3 expression and acridine orange assay. In addition, BSN induced paraptosis through increasing the reactive oxygen species (ROS) production, mitochondria damage, and endoplasmic reticulum (ER) stress. Moreover, BSN promoted the activation of the MAPK signaling pathway, and pharmacological inhibitors of this signaling pathway could alleviate all three forms of cell death induced by BSN. Our data indicated that BSN could initiate the activation of apoptosis, autophagy, and paraptosis through modulating the MAPK signaling pathway.

Piperlongumine overcomes imatinib resistance by inducing proteasome inhibition in chronic myelogenous leukemia cells

ETHNOPHARMACOLOGICAL RELEVANCE

Piper longum L., an herbal medicine used in India and other Asian countries, is prescribed routinely for a range of diseases, including tumor. Piperlongumine, a natural product isolated from Piper longum L., has received widespread attention due to its various pharmacological activities, such as anti-inflammatory, antimicrobial, and antitumor effects.

AIM OF THE STUDY

Chronic myelogenous leukemia (CML) is a hematopoietic disease caused by Bcr-Abl fusion gene, with an incidence of 15% in adult leukemias. Targeting Bcr-Abl by imatinib provides a successful treatment approach for CML. However, imatinib resistance is an inevitable issue for CML treatment. In particular, T315I mutant is the most stubborn of the Bcr-Abl point mutants associated with imatinib resistance. Therefore, it is urgent to find an alternative approach to conquer imatinib resistance. This study investigated the role of a natural product piperlongumine in overcoming imatinib resistance in CML.

MATERIALS AND METHODS

Cell viability and apoptosis were evaluated by MTS assay and Annexin V/propidium iodide counterstaining assay, respectively. Levels of intracellular signaling proteins were assessed by Western blots. Mitochondrial membrane potential was reflected by the fluorescence intensity of rhodamine-123. The function of proteasome was detected using 20S proteasomal activity assay, proteasomal deubiquitinase activity assay, and deubiquitinase active-site-directed labeling. The antitumor effects of piperlongumine were assessed with mice xenografts.

RESULTS

We demonstrate that (i) Piperlongumine inhibits proteasome function by targeting 20S proteasomal peptidases and 19S proteasomal deubiquitinases (USP14 and UCHL5) in Bcr-Abl-WT and Bcr-Abl-T315I CML cells; (ii) Piperlongumine inhibits the cell viability of CML cell lines and primary CML cells; (iii) Proteasome inhibition by piperlongumine leads to cell apoptosis and downregulation of Bcr-Abl; (iv) Piperlongumine suppresses the tumor growth of CML xenografts.

CONCLUSIONS

These results support that blockade of proteasome activity by piperlongumine provides a new therapeutic strategy for treating imatinib-resistant CML.

Effects of ABCG2 C421A and ABCG2 G34A genetic polymorphisms on clinical outcome and response to imatinib mesylate, in Iranian chronic myeloid leukemia patients

Background

Chronic myeloid leukemia (CML) is a multifactorial clonal myeloid neoplasm that mainly arises from the Philadelphia chromosome. Even though imatinib mesylate (IM) is considered the gold standard for first-line treatment, a number of CML patients have shown IM resistance that can be influenced by many factors, including pharmacogenetic variability. The present study examined whether two common single nucleotide polymorphisms (SNPs) of ABCG2 (G34A and C421A) contribute to IM resistance and/or good responses.

Material and methods

A total of 72 CML patients were genotyped with high-resolution melting (HRM) and restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR). We also determined the cytogenetic and hematological response, as evaluable factors for measuring response to imatinib.

Results

In the current study, we explored the relationship between the different variants of ABCG2 G34A and C421A and clinical response to imatinib among CML patients. There were no statistically significant differences between genotypes of C421A and G34A and allele frequencies among the resistant and responder groups, with response to IM (P > 0.05). Also, we found no statistically significant association between genotypes and cytogenetic and hematological responses.

Conclusion

This is the first study to investigate the association between genotypes of the G34A and C421A SNPs and the outcome of IM treatment in Iranian population. As a whole, genotyping of these SNPs is unhelpful in predicting IM response in CML patients.

Antileukemic Activity of hsa-miR-203a-5p by Limiting Glutathione Metabolism in Imatinib-Resistant K562 Cells

Imatinib has been the first and most successful tyrosine kinase inhibitor (TKI) for chronic myeloid leukemia (CML), but many patients develop resistance to it after a satisfactory response. Glutathione (GSH) metabolism is thought to be one of the factors causing the emergence of imatinib resistance. Since hsa-miR-203a-5p was found to downregulate Bcr-Abl1 oncogene and also a link between this oncogene and GSH metabolism is reported, the present study aimed to investigate whether hsa-miR-203a-5p could overcome imatinib resistance by targeting GSH metabolism in imatinib-resistant CML cells. After the development of imatinib-resistant K562 (IR-K562) cells by gradually exposing K562 (C) cells to increasing doses of imatinib, resistant cells were transfected with hsa-miR-203a-5p (R+203). Thereafter, cell lysates from various K562 cell sets (imatinib-sensitive, imatinib-resistant, and miR-transfected imatinib-resistant K562 cells) were used for GC-MS-based metabolic profiling. L-alanine, 5-oxoproline (also known as pyroglutamic acid), L-glutamic acid, glycine, and phosphoric acid (Pi)-five metabolites from our data, matched with the enumerated 28 metabolites of the MetaboAnalyst 5.0 for the GSH metabolism. All of these metabolites were present in higher concentrations in IR-K562 cells, but intriguingly, they were all reduced in R+203 and equated to imatinib-sensitive K562 cells (C). Concludingly, the identified metabolites associated with GSH metabolism could be used as diagnostic markers.

Adverse events and dose modifications of tyrosine kinase inhibitors in chronic myelogenous leukemia

The prognosis of chronic myelogenous leukemia (CML-CP) in chronic phase has improved dramatically since the introduction of imatinib. In addition to imatinib, second- and third-generation tyrosine kinase inhibitors (TKIs) and a novel allosteric inhibitor, asciminib, are now available. During long-term TKI therapy, the optimal selection of TKI therapy for individual patients requires the understanding of specific patterns of toxicity profile to minimize chronic toxicity and the risk of adverse events, including pulmonary arterial hypertension, pleural effusion, and cardiovascular events. Given the high efficacy of TKI therapy, dose modifications of TKI therapy reduce the risk of toxicities and improves quality of life during therapy. In this review article, we summarize the characteristics and adverse event profile of each TKI and dose modifications in patients with CML-CP and discuss future perspectives in the treatment of CML-CP.

Leelamine Modulates STAT5 Pathway Causing Both Autophagy and Apoptosis in Chronic Myelogenous Leukemia Cells

Simple Summary

Autophagy is a cellular mechanism that is essential for removing misfolded proteins and damaged organelles. Moreover, the aberrant activation of signal transducer and activator of transcription 5 (STAT5), which can regulate cellular survival and homeostasis, has been often observed in different malignancies. In this study, we demonstrate that leelamine inhibits the STAT5 phosphorylation while inducing autophagy as well as apoptosis in chronic myeloid leukemia cells. Leelamine induces autophagy by stimulating the expression of Atg7, beclin-1, and the production of autophagosomes, which leads to substantial inhibition of STAT5 activation.

Abstract

Leelamine (LEE) has recently attracted significant attention for its growth inhibitory effects against melanoma, breast cancer, and prostate cancer cells; however, its impact on hematological malignancies remains unclear. Here, we first investigate the cytotoxic effects of LEE on several human chronic myeloid leukemia (CML) cells. We noted that LEE stimulated both apoptosis and autophagy in CML cells. In addition, the constitutive activation of signal transducer and activator of transcription 5 (STAT5) was suppressed substantially upon LEE treatment. Moreover, STAT5 knockdown with small interfering RNA (siRNA) increased LEE-induced apoptosis as well as autophagy and affected the levels of various oncogenic proteins. Thus, the targeted mitigation of STAT5 activation by LEE can contribute to its diverse anticancer effects by enhancing two distinct cell death pathways.

Effect of D-mannose on Philadelphia chromosome-positive leukemia cells

BACKGROUND

Although Abelson (ABL) tyrosine kinase inhibitors (TKIs) have demonstrated potency against chronic myeloid leukemia (CML), resistance to ABL TKIs can develop in CML patients after discontinuation of therapy.

OBJECTIVE

Glucose metabolism may be altered in CML cells because glucose is a key metabolite used by tumor cells. We investigated whether D-mannose treatment induced metabolic changes in CML cells and reduced CML growth in the presence of ABL TKIs.

METHODS

We investigated whether D-mannose treatment induced metabolic changes in CML cells and reduced CML growth in the presence of ABL TKIs.

RESULTS

Treatment with D-mannose for 72 h inhibited the growth of K562 cells. Combined treatment using ABL TKIs and D-mannose induced a significantly higher level of cytotoxicity in Philadelphia chromosome (Ph)-positive leukemia cells than in control cells. In the mouse model, severe toxicity was observed as evidenced by body weight loss in the ponatinib and D-mannose combination treatment groups.

CONCLUSION

Our results indicate that metabolic reprogramming may be a useful strategy against Ph-positive leukemia cells. However, caution should be exercised during clinical applications.

Upgrade of an old drug: Auranofin in innovative cancer therapies to overcome drug resistance and to increase drug effectiveness

Auranofin is an oral gold(I) compound, initially developed for the treatment of rheumatoid arthritis. Currently, Auranofin is under investigation for oncological application within a drug repurposing plan due to the relevant antineoplastic activity observed both in vitro and in vivo tumor models. In this review, we analysed studies in which Auranofin was used as a single drug or in combination with other molecules to enhance their anticancer activity or to overcome chemoresistance. The analysis of different targets/pathways affected by this drug in different cancer types has allowed us to highlight several interesting targets and effects of Auranofin besides the already well-known inhibition of thioredoxin reductase. Among these targets, inhibitory-κB kinase, deubiquitinates, protein kinase C iota have been frequently suggested. To rationalize the effects of Auranofin by a system biology-like approach, we exploited transcriptomic data obtained from a wide range of cell models, extrapolating the data deposited in the Connectivity Maps website and we attempted to provide a general conclusion and discussed the major points that need further investigation.

Philadelphia chromosome-positive B-cell acute lymphoblastic leukemia with e1a3 BCR-ABL1 transcript in a Nigerian with sickle cell anemia: a case report

Background

The occurrence of acute leukemia in patients with sickle cell anemia is uncommon. The Philadelphia chromosome is the hallmark of chronic myeloid leukemia. However, it may also be associated with acute lymphoblastic leukemia and acute myeloblastic leukemia. The common BCR-ABL1 transcripts seen in acute lymphoblastic leukemia are e1a2, e13a2, and e14a2, while other transcripts such as e1a3, e13a3, and e6a2 occur rarely. This report describes the presentation, management, and outcome of the occurrence of B-cell acute lymphoblastic leukemia with the rare e1a3 BCR-ABL1 transcript in a patient with sickle cell anemia.

Case presentation

A 19-year-old male Nigerian, a known sickle cell anemia patient was admitted on account of severe vaso-occlusive crisis. Examination revealed fever, palor, and jaundice. Full blood count showed anemia and leukocytosis. Peripheral blood and bone marrow smears revealed numerous large and small lymphoblasts in keeping with the L2 subtype of acute lymphoblastic leukemia based on the French–American–British classification. Further evaluation was in keeping with a diagnosis of BCR-ABL1-positive mature B-cell acute lymphoblastic leukemia associated with the rare e1a3 transcript. He was commenced simultaneously on induction chemotherapy and Imatinib while being prepared for allogeneic stem cell transplantation. However, he died  six  months after diagnosis from meningoencephalitis.

Conclusion

The occurrence of acute lymphoblastic leukemia with a rare BCR-ABL1 e1a3 transcript in association with sickle cell anemia is uncommon and associated with poor prognosis.

Pyrimethamine Modulates Interplay between Apoptosis and Autophagy in Chronic Myelogenous Leukemia Cells

Pyrimethamine (Pyri) is being used in combination with other medications to treat serious parasitic infections of the body, brain, or eye and to also reduce toxoplasmosis infection in the patients with HIV infection. Additionally, Pyri can display significant anti-cancer potential in different tumor models, but the possible mode of its actions remains unclear. Hence, in this study, the possible anti-tumoral impact of Pyri on human chronic myeloid leukemia (CML) was deciphered. Pyri inhibited cell growth in various types of tumor cells and exhibited a marked inhibitory action on CML cells. In addition to apoptosis, Pyri also triggered sustained autophagy. Targeted inhibition of autophagy sensitized the tumor cells to Pyri-induced apoptotic cell death. Moreover, the activation of signal transducer and activator of transcription 5 (STAT5) and its downstream target gene Bcl-2 was attenuated by Pyri. Accordingly, small interfering RNA (siRNA)-mediated STAT5 knockdown augmented Pyri-induced autophagy and apoptosis and promoted the suppressive action of Pyri on cell viability. Moreover, ectopic overexpression of Bcl-2 protected the cells from Pyri-mediated autophagy and apoptosis. Overall, the data indicated that the attenuation of STAT5-Bcl-2 cascade by Pyri can regulate its growth inhibitory properties by simultaneously targeting both apoptosis and autophagy cell death mechanism(s).

Polymeric siRNA delivery targeting integrin-β1 could reduce interactions of leukemic cells with bone marrow microenvironment

Uncontrolled proliferation of the myeloid cells due to BCR-ABL fusion has been successfully treated with tyrosine kinase inhibitors (TKIs), which improved the survival rate of Chronic Myeloid Leukemia (CML) patients. However, due to interactions of CML cells with bone marrow microenvironment, sub-populations of CML cells could become resistant to TKI treatment. Since integrins are major cell surface molecules involved in such interactions, the potential of silencing integrin-β1 on CML cell line K562 cells was explored using short interfering RNA (siRNA) delivered through lipid-modified polyethyleneimine (PEI) polymers. Reduction of integrin-β1 in K562 cells decreased cell adhesion towards human bone marrow stromal cells and to fibronectin, a major extracellular matrix protein for which integrin-β1 is a primary receptor. Interaction of K562 cells with fibronectin decreased the sensitivity of the cells to BCR-ABL siRNA treatment, but a combinational treatment with integrin-β1 and BCR-ABL siRNAs significantly reduced colony forming ability of the cells. Moreover, integrin-β1 silencing enhanced the detachment of K562 cells from hBMSC samples (2 out of 4 samples), which could make them more susceptible to TKIs. Therefore, the polymeric-siRNA delivery targeting integrin-β1 could be beneficial to reduce interactions with bone marrow microenvironment, aiding in the response of CML cells to therapeutic treatment.

The potential of proliferative and apoptotic parameters in clinical flow cytometry of myeloid malignancies

Standardization of the detection and quantification of leukocyte differentiation markers by the EuroFlow Consortium has led to a major step forward in the integration of flow cytometry into classification of leukemia and lymphoma. In our opinion, this now enables introduction of markers for more dynamic parameters, such as proliferative and (anti)apoptotic markers, which have proven their value in the field of histopathology in the diagnostic process of solid tumors and lymphoma. Although use of proliferative and (anti)apoptotic markers as objective parameters in the diagnostic process of myeloid malignancies was studied in the past decades, this did not result in the incorporation of these biomarkers into clinical diagnosis. This review addresses the potential of these markers for implementation in the current, state-of-the-art multiparameter analysis of myeloid malignancies. The reviewed studies clearly recognize the importance of proliferation and apoptotic mechanisms in the pathogenesis of bone marrow (BM) malignancies. The literature is, however, contradictory on the role of these processes in myelodysplastic syndrome (MDS), MDS/myeloproliferative neoplasms, and acute myeloid leukemia. Furthermore, several studies underline the need for the analysis of the proliferative and apoptotic rates in subsets of hematopoietic BM cell lineages and argue that these results can have diagnostic and prognostic value in patients with myeloid malignancies. Recent developments in multiparameter flow cytometry now allow quantification of proliferative and (anti)apoptotic indicators in myeloid cells during their different maturation stages of separate hematopoietic cell lineages. This will lead to a better understanding of the biology and pathogenesis of these malignancies.

LncRNA highly upregulated in liver cancer regulates imatinib resistance in chronic myeloid leukemia via the miR-150-5p/MCL1 axis

Chronic myeloid leukemia (CML) is a type of myeloproliferative neoplasm. Aberrant expression of long noncoding RNA highly upregulated in liver cancer (HULC) has been implicated in tumor progression, including CML. This study aimed to investigate the role of HULC in CML. The levels of HULC, miR-150-5p and myeloid cell leukemia 1 (MCL1) were examined by quantitative real-time PCR or western blot assay. Cell counting kit-8 assay was used to detect cell viability and half inhibition concentration. Cell apoptosis was monitored by flow cytometry and western blot. The interaction among HULC, miR-150-5p and MCL1 was validated by dual-luciferase reporter assay. The expression of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT) and phosphorylation-AKT was evaluated using western blot assay. HULC and MCL1 were upregulated, whereas miR-150-5p was downregulated in bone marrow mononuclear cells of CML patients and CML cells. HULC overexpression increased imatinib resistance in K562 cells, and HULC depletion enhanced imatinib sensitivity in imatinib-resistant cells (K562-R). Mechanically, HULC was a sponge of miR-150-5p. HULC contributed to imatinib resistance through regulation of miR-150-5p. MCL1 bound to miR-150-5p and reversed the effect of HULC on imatinib resistance. HULC regulated the PI3K/AKT pathway via the miR-150-5p/MCL1 axis. These findings indicated that HULC enhanced imatinib resistance in CML by modulating the miR-150-5p/MCL1 axis, providing a promising biomarker for CML.

Efficacy of tyrosine kinase inhibitors on a mouse chronic myeloid leukemia model and chronic myeloid leukemia stem cells

Chronic myeloid leukemia (CML) is a hematopoietic stem cell disorder caused by constitutively active BCR-ABL1 tyrosine kinase resulting from the t(9;22) Philadelphia translocation. Imatinib, a BCR-ABL1 tyrosine kinase inhibitor (TKI), is a revolutionary molecular target inhibitor for CML. However, leukemic stem cells (LSCs) eventually become resistant to imatinib and thereby cause relapse. The next-generation BCR-ABL1 TKI dasatinib is also unable to eliminate CML LSCs. On the other hand, the third-generation BCR-ABL1 TKI ponatinib is not well studied in terms of its efficacy on CML LSCs. Here, we evaluate the efficacy of ponatinib against CML LSC-containing lin^-Sca-1⁺c-Kit⁺ (LSK) cells using a mouse CML-like model. To this end, we compared the efficacy of imatinib, dasatinib, and ponatinib on CML LSK cells and showed that ponatinib is more effective at eliminating CML LSK cells. Our results suggest that ponatinib could be potentially useful for achieving treatment-free remission in CML patients.

Relationship between trough level of tyrosine kinase inhibitor (imatinib and nilotinib) and BCR-ABL ratios in an Indonesian chronic-phase chronic myeloid leukemia (CML) population

Objectives Among Chronic Myeloid Leukemia (CML) patients treated with Tyrosine Kinase Inhibitor (TKI-imatinib-nilotinib), some showed a suboptimal response. Based on pharmacokinetic studies, TKI trough level ( C m i n ∞ ${C}_{min}\hat{\infty }$ ) is associated with clinical outcomes, reflected by the BCR-ABL ratio. However, the interindividual pharmacokinetic variability of imatinib and nilotinib is found to be moderate-high. This study aims to analyze the relationship between TKI C m i n ∞   ${C}_{min}\hat{\infty }$ and BCL-ABL ratio in chronic-phase CML patients. Methods Cross-sectional study to CML chronic-phase patients treated with imatinib 400 mg daily or nilotinib 400 or 800 mg daily for ≥12 months. The exclusion criteria were therapy discontinuation within 29 days (imatinib) or 8 days (nilotinib) before the sampling day. Blood samples were drawn 1 h before the next dose. Imatinib-nilotinib C m i n ∞ ${C}_{min}\hat{\infty }$ and BCR-ABL ratio were measured using HPLC and RT-qPCR. The relationship was analyzed using bivariate correlation Spearman's rho test. Results Twenty-three imatinib and 11 nilotinib patients met the inclusion criteria. The mean imatinib and nilotinib C m i n ∞ ${C}_{min}\hat{\infty }$ were 1,065.46 ± 765.71 and 1,445 ± 1,010.35 ng/mL respectively. There were large interindividual variations in both groups (71.87% vs. 69.88%). Half of the patients in each group were found to reach C m i n ∞ ${C}_{min}\hat{\infty }$ target (≥1.000 ng/mL, imatinib; ≥800 ng/mL nilotinib), but only 12 (35,29%) of them result in BCR-ABL ratio ≤0.1%. C m i n ∞   ${C}_{min}\hat{\infty }$ imatinib was found to be significantly associated with BCR-ABL ratio. But, not with the nilotinib group. Conclusions There were high interindividual variations of imatinib and nilotinib correlated with BCR-ABL ratio, but no correlation in nilotinib.

Synthesis and Characterization of Telmisartan-Derived Cell Death Modulators to Circumvent Imatinib Resistance in Chronic Myeloid Leukemia

New strategies to eradicate cancer stem cells in chronic myeloid leukemia (CML) include a combination of imatinib with peroxisome proliferator-activated receptor gamma (PPARγ) ligands. Recently, we identified the partial PPARγ agonist telmisartan as effective sensitizer of resistant K562 CML cells to imatinib treatment. Here, the importance of the heterocyclic core on the cell death-modulating effects of the telmisartan-derived lead 4'-((2-propyl-1H-benzo[d]imidazol-1-yl)methyl)-[1,1'-biphenyl]-2-carboxylic acid (3 b) was investigated. Inspired by the pharmacodynamics of HYL-6d and the selective PPARγ ligand VSP-51, the benzimidazole was replaced by a carbazole or an indole core. The results indicate no correlation between PPARγ activation and sensitization of resistant CML cells to imatinib. The 2-COOH derivatives of the carbazoles or indoles achieved low activity at PPARγ, while the benzimidazoles showed 60-100 % activation. Among the 2-CO2 CH3 derivatives, only the ester of the lead (2 b) slightly activated PPARγ. Sensitizing effects were further observed for this non-cytotoxic 2 b (80 % cell death), and to a lesser extent for the lead 3 b or the 5-Br-substituted ester of the benzimidazoles (5 b).

A Small Molecule Inhibitor, OGP46, Is Effective against Imatinib-Resistant BCR-ABL Mutations via the BCR-ABL/JAK-STAT Pathway

Chronic myeloid leukemia (CML) is caused by the Philadelphia (Ph⁺) chromosome carrying the BCR-ABL oncogene, a constitutively active tyrosine kinase. The discovery of imatinib represents a major success story in the treatment against CML. However, mutations in the BCR-ABL kinase domain are a major cause of resistance to imatinib, demonstrating that BCR-ABL remains a critical drug target. Here, we investigate a novel small molecule inhibitor, OGP46, for its inhibitory activity against K562, a panel of murine BaF3 cell lines stably expressing either wild-type BCR-ABL or its mutant forms, including T315I. OGP46 exhibits potent activity against imatinib-resistant BCR-ABL mutations, including T315I. OGP46 induced cell differentiation accompanied by G0/G1 cell-cycle arrest and suppressed the colony formation capacity of cells. Treatment with OGP46 significantly decreased the mRNA and protein expression of BCR-ABL in K562 and BaF3-p210-T315I cells. Mechanistically, the anti-cancer activity of OGP46 induced by cell differentiation is likely through the BCR-ABL/JAK-STAT pathway in native BCR-ABL and mutant BCR-ABL, including T315I, of CML cells. Our findings highlight that OGP46 is active against not only native BCR-ABL but also 11 clinically relevant BCR-ABL mutations, including T315I mutation, which are resistant to imatinib. Thus, OGP46 may be a novel strategy for overcoming imatinib-resistance BCR-ABL mutations, including T315I.

BCR-ABL Gene Transcript Types of Patients with Chronic Myelogenous Leukemia in Yogyakarta, Indonesia

Background:

The aim of this study was analyzing the BCR-ABL transcript types of patients with chronic myeloid leukemia (CML) in Dr Sardjito General Hospital, Yogyakarta, Indonesia. This study is very relevant because the data concerning BCR-ABL gene transcript types is very limited in Indonesia. Furthermore, it is important for patient’s management, particularly in defining the tyrosine kinase inhibitors (TKIs) therapy and monitoring after therapy. The introduction of TKIs has become a major advance in the management of patients with CML, especially in the chronic phase (CML-CP), in which most patients are diagnosed.

Methods:

One hundred eighty five (185) of 370 recruited patients were included in this study (2010–2014). RNA samples were isolated from mononuclear cells of peripheral blood of the subjects taken at primary diagnosis. Detection of BCR-ABL gene transcript types was done using multiplex reverse transcriptase PCR (multiplex RT-PCR) and/or nested PCR following the cDNA synthesis. When the first PCR set failed to amplify the BCR-ABL gene, RT-conventional PCR and/or nested PCR would be applied. The proportion of each transcript type was calculated among the BCR-ABL positive CML patients.

Results:

Approximately 99% (183/185) of CML patients are BCR-ABL positive, with the most common type is major b3a2 (136/183; 74.3%), followed by major b2a2 (41/183; 22.4%). Two samples (1.1%) showed co-expression of b3a2 and b2a2; 1 sample showed co-expression of b3a2 and fragment at 500bp; and 3 samples showed uncommon fragments.

Conclusion:

Ninety nine percent (99%) of CML patients in Yogyakarta, Indonesia are BCR-ABL positive, with 74.3% have b3a2 transcript, 22.4% have b2a2 trascript, 1.1% have co-expression of b3a2 and b2a2 transcript, and the rest (2.2%) have uncommon bands that still need to be confirmed.

Genomic variation as a marker of response to neoadjuvant therapy in locally advanced rectal cancer

There is variation in the responsiveness of locally advanced rectal cancer to neoadjuvant chemoradiation, from complete response to total resistance. This study compared genetic variation in rectal cancer patients who had a complete response to chemoradiation versus poor response, using tumor tissue samples sequenced with genomics analysis software. Rectal cancer patients treated with chemoradiation and proctectomy June 2006-March 2017 were grouped based on response to chemoradiation: those with no residual tumor after surgery (CR, complete responders, AJCC-CPR tumor grade 0, n = 8), and those with poor response (PR, AJCC-CPR tumor grade two or three on surgical resection, n = 8). We identified 195 variants in 83 genes in tissue specimens implicated in colorectal cancer biopathways. PR patients showed mutations in four genes not mutated in complete responders: KDM6A, ABL1, DAXX-ZBTB22, and KRAS. Ten genes were mutated only in the CR group, including ARID1A, PMS2, JAK1, CREBBP, MTOR, RB1, PRKAR1A, FBXW7, ATM C11orf65, and KMT2D, with specific discriminating variants noted in DMNT3A, KDM6A, MTOR, APC, and TP53. Although conclusions may be limited by small sample size in this pilot study, we identified multiple genetic variations in tumor DNA from rectal cancer patients who are poor responders to neoadjuvant chemoradiation, compared to complete responders.

Nilotinib Treatment of Patients Affected by Chronic Graft-versus-Host Disease Reduces Collagen Production and Skin Fibrosis by Downmodulating the TGF-β and p-SMAD Pathway

The present study was conducted to investigate cellular and molecular features of chronic graft-versus-host disease fibroblasts (GVHD-Fbs) and to assess the effectiveness of nilotinib as a fibrosis modulator. Growth kinetics, phenotype, and differentiation of cultured skin biopsy-derived GVHD-Fbs were compared with normal fibroblasts from both a dermal cell line (n-Fbs) and healthy individuals undergoing cosmetic surgery (n-skin-Fbs). Collagen genes (COL1α1/COL1α2) and p-SMAD2 expression were assessed by real-time PCR and immunofluorescence. The in vivo effects of nilotinib on chronic GVHD (cGVHD)-affected skin were investigated by immunohistochemistry; the relationship to TGF-β plasma levels was assessed. Although the morphology, phenotype, and differentiation of cultured GVHD-Fbs were comparable to normal fibroblasts, growth was slower and senescence was reached earlier. The expression of COL1α1 and COL1α2 mRNAs was respectively 4 and 1.6 times higher in cGVHD-Fbs (P = .02); the addition of TGF-β increased n-Fbs, but not GVHD-Fbs, collagen gene expression. Compared with the baseline, the addition of 1 μM nilotinib induced 86.5% and 49% reduction in COL1α1 and COL1α2 expression in cultured GVHD-Fbs, respectively (P< .01). In vivo immunohistochemistry analysis of skin biopsy specimens from patients with cGVHD showed strong baseline staining for COL1α1 and COL1α2, which decreased sharply after 180 days of nilotinib; immunofluorescence revealed TGF-β inhibition and p-Smad2 reduction at the intracellular level. Of note, nilotinib treatment was associated with normalization of TGF-β levels both in culture supernatants and in plasma. In general, the data show that cGVHD fibroblasts promote fibrosis through abnormal collagen production induced by hyperactive TGF-β signaling. TGF-β inhibition at the intracellular and systemic level represents an essential antifibrotic mechanism of nilotinib in a clinical setting.

Effect of dual inhibition of histone deacetylase and phosphatidylinositol-3 kinase in Philadelphia chromosome-positive leukemia cells

PURPOSE

ABL tyrosine kinase inhibitors (TKIs) have demonstrated potency in the treatment of chronic myeloid leukemia (CML) patients. However, resistance to ABL TKIs can develop in CML patients due to BCR-ABL point mutations. Furthermore, CUDC-907 is an oral inhibitor of class I phosphoinositide 3-kinase (PI3K) as well as class I and II histone deacetylase (HDAC) enzymes.

METHODS

In this study, we evaluated the effect of combination therapy of CUDC-907 and ABL TKIs, using BCR-ABL-positive cell lines and primary samples.

RESULTS

CUDC-907 treatment for 72 h resulted in cell growth inhibition. Over the same period, an increase in histone acetylation and both caspase three and poly (ADP-ribose) polymerase (PARP) enzyme activity was observed. When ABL TKI treatment and CUDC-907 treatment were combined, significantly greater cytotoxicity was observed. Moreover, combined oral therapy with ponatinib (20 mg/kg/day) and CUDC-907 (30 mg/kg/day) greatly inhibited tumor growth compared to each drug alone. Lastly, CUDC-907 treatment also inhibited the growth of Ba/F3 ponatinib-resistant cells, K562 nilotinib-resistant cells, and T315I mutant primary samples.

CONCLUSION

Taken together, our results indicate that administration of CUDC-907, a dual PI3K and HDAC inhibitor, may be an effective strategy against ABL TKI-resistant cells, including cells harboring the T315I mutation. Moreover, CUDC-907 may enhance the cytotoxic effects of ABL TKI when a combined treatment strategy is used against Philadelphia chromosome-positive leukemia cells.

A Chemical Approach to Overcome Tyrosine Kinase Inhibitors Resistance: Learning from Chronic Myeloid Leukemia

BACKGROUND

The possibilities of treatment for oncological diseases are growing enormously in the last decades. Unfortunately, these developments have led to the onset of resistances with regards to the new treatments. This is particularly true if we face with the therapeutic field of Tyrosine Kinase Inhibitors (TKIs). This review gives an overview of possible TKI resistances that can occur during the treatment of an oncologic diesease and available strategies that can be adopted, taking cues from a successful example such as CML.

METHODS

We performed a literature search for peer-reviewed articles using different databases, such as PubMed and Scopus, and exploiting different keywords and different logical operators.

RESULTS

68 papers were included in the review. Twenty-four papers give an overview of the causes of TKIs resistances in the wide oncologic field. The remaining papers deal CML, deeply analysing the TKIs Resistances present in this pathology and the strategies adopted to overcome them.

CONCLUSION

The aim of this review is to furnish an overview and a methodological guideline for the approach and the overcoming of TKIs Resistances.

USP10 modulates the SKP2/Bcr-Abl axis via stabilizing SKP2 in chronic myeloid leukemia

Constitutive activation of tyrosine kinase Bcr-Abl is the leading cause of the development and progression of chronic myeloid leukemia (CML). Currently, the application of tyrosine kinase inhibitors (TKIs) targeting the Bcr-Abl is the primary therapy for CML patients. However, acquired resistance to TKIs that develops overtime in the long-term administration renders TKIs ineffective to patients with advanced CML. Therefore, increasing studies focus on the amplified expression or activation of Bcr-Abl which is proposed to contribute to the advanced phase. Here, we show that S-phase kinase-associated protein 2 (SKP2) acts as a co-regulator of Bcr-Abl by mediating its K63-linked ubiquitination and activation. Further investigations show that USP10 as a novel deubiquitinase of SKP2 amplifies the activation of Bcr-Abl via mediating deubiquitination and stabilization of SKP2 in CML cells. Moreover, inhibition of USP10 significantly suppresses the proliferation of both imatinib-sensitive and imatinib-resistant CML cells, which likely depends on SKP2 status. This findings are confirmed in primary CML cells because these cells are over-expressed with USP10 and SKP2 and are sensitive to a USP10 inhibitor. Taken together, the present study not only provides a novel insight into the amplified activation of Bcr-Abl in CML, but also demonstrates that targeting the USP10/SKP2/Bcr-Abl axis is a potential strategy to overcome imatinib resistance in CML patients.

miR-302 cluster inhibits angiogenesis and growth of K562 leukemia cells by targeting VEGFA

Background

miR-302 cluster has been reported as a tumor suppressor in many human cancers; yet, its function in chronic myeloid leukemia (CML) tumorigenesis remains largely unclear. The study was aimed to explore the functional roles of miR-302 cluster in CML progression.

Materials and methods

Quantitative reverse transcriptase PCR and Western blot were performed to evaluate miR-302 cluster and vascular endothelial growth factor A (VEGFA) expression levels. Cell Counting Kit-8 assay, colony formation assay and human umbilical vein endothelial cell line capillary tube formation were used to determine the influence of miR-302 cluster on the growth and angiogenesis of K562 cells, respectively. Luciferase reporter assay was employed to confirm the direct target interaction between miR-302 cluster and VEGFA.

Results

This study demonstrated that miR-302 cluster was frequently downregulated in CML samples and cell lines and high level of miR-302 cluster was significantly associated with good prognosis of CML patients. Compared with miRNA negative control, miR-302 cluster mimics obviously suppressed cell growth, colony formation and angiogenesis. Further studies revealed that VEGFA was a direct target gene of miR-302 cluster. Moreover, overexpression of VEGFA dramatically abated the inhibition of miR-302 cluster on cell growth and angiogenesis.

Conclusion

The present study, for the first time, identified miR-302 cluster as a tumor suppressor, and overexpression of miR-302 cluster inhibited growth and angiogenesis in K562 cells. miR-302 cluster may be a potential therapeutic target in CML to develop the adjuvant antiangiogenic therapy based on VEGFA.

Aberrant DNA methylation at HOXA4 and HOXA5 genes are associated with resistance to imatinib mesylate among chronic myeloid leukemia patients

BACKGROUND

Imatinib mesylate is a molecularly targeted tyrosine kinase inhibitor drug. It is effectively used in the treatment of chronic myeloid leukemia (CML) patients. However, development of resistance to imatinib mesylate as a result of BCR-ABL dependent and BCR-ABL independent mechanisms has emerged as a daunting problem in the management of CML patients. Between these mechanisms, BCR-ABL independent mechanisms are still not robustly understood.

AIM

To investigate the correlation of HOXA4 and HOXA5 promoter DNA hypermethylation with imatinib resistance among CML patients.

METHODS AND RESULTS

Samples from 175 Philadelphia positive CML patients (83 good response and 92 BCR-ABL non-mutated imatinib resistant patients) were subjected to Methylation Specific High Resolution Melt Analysis for methylation levels quantification of the HOXA4 and HOXA5 promoter regions. Receiver operating characteristic curve analysis was done to elucidate the optimal methylation cut-off point followed by multiple logistic regression analysis. Log-Rank analysis was done to measure the overall survival difference between CML groups. The optimal methylation cut-off point was found to be at 62.5% for both HOXA4 and HOXA5. Chronic myeloid leukemia patients with ≥63% HOXA4 and HOXA5 methylation level were shown to have 3.78 and 3.95 times the odds, respectively, to acquire resistance to imatinib. However, overall survival of CML patients that have ≤62% and ≥ 63% methylation levels of HOXA4 and HOXA5 genes were found to be not significant (P-value = 0.126 for HOXA4; P-value = 0.217 for HOXA5).

CONCLUSION

Hypermethylation of the HOXA4 and HOXA5 promoter is correlated with imatinib resistance and with further investigation, it could be a potential epigenetic biomarker in supplement to the BCR-ABL gene mutation in predicting imatinib treatment response among CML patients but could not be considered as a prognostic marker.

Real world treatment patterns in chronic myeloid leukemia patients newly initiated on tyrosine kinase inhibitors in an U.S. integrated healthcare system

Purpose To evaluate treatment patterns in patients diagnosed with incident chronic myelogenous leukemia (CML) newly initiating therapy with imatinib, dasatinib, or nilotinib. Patients were followed to determine switching and discontinuation rates. Factors associated with switching or discontinuation from index TKI therapy, reasons for discontinuation based on electronic chart notes, and frequency of laboratory monitoring were assessed during the follow-up period. Methods A retrospective cohort study was conducted in chronic myelogenous leukemia patients aged ≥ 18 years who were identified from the Kaiser Permanente Southern California (KPSC) Cancer Registry database during the study time period of 1 January 2007 to 12 December 2013. The index date was defined as the date of the first TKI prescription (imatinib, dasatinib, or nilotinib) identified during the study time period with no prior history of TKI use within 12 months. Patients had to have continuous membership with drug benefit eligibility and no prior history of stem cell transplant (SCT) or other cancers during the 12 months prior to the index date. Baseline characteristics were identified during 12 months prior to the index date and outcomes were identified during the follow-up period after the index date. All patients were followed from index TKI therapy until end of study time period (12 December 2014), death, stem cell transplant, or disenrollment from the health plan unless one of the following occurred first: a patient switched their index therapy, or a patient discontinued their index therapy. Forward stepwise selection multivariable logistic regression models were used to evaluate factors associated with patients who continued therapy compared to those who switched or discontinued therapy with the index TKI. Chart notes were reviewed 30 days prior and 30 days post index TKI discontinuation to evaluate reasons for discontinuation. Molecular and cytogenetic testing frequency was also assessed during the follow-up period among the different patient groups. Results Two hundred sixteen patients were identified with incident chronic myelogenous leukemia and use of TKI therapy: 189 (87.5%) received imatinib, 19 (8.8%) received dasatinib, and 8 (3.7%) received nilotinib. The mean age on index date was 53 years and 63% were male; 103 patients (48%) continued on their index therapy, while 62 patients (28%) switched, and 51 patients (24%) discontinued.

Chk1 inhibitors overcome imatinib resistance in chronic myeloid leukemia cells

Drug resistance to tyrosine kinase inhibitors (TKIs) is currently a clinical problem of chronic myelogenous leukemia (CML). Bcr-Abl protein depletion is considered as a way to overcome drug resistance to TKIs. In our study, Chk1 inhibitors, AZD7762 and MK-8776, had strong antitumor effects on CML cell line KBM5 and imatinib-resistant form KBM5^T315I. Moreover, Chk1 inhibitors showed a strong cytotoxic effect on leukemia cells from primary CML and imatinib-resistance CML patients, but low cytotoxic effect on normal human mononuclear cells. Then, we found that Chk1 inhibitors induced apoptosis and increased DNA damage in CML cell lines with the degradation of the Bcr-Abl protein. Using the proteasome inhibitor and an immunoprecipitation assay, we found that Chk1 inhibitors triggered the degradation of Bcr-Abl through ubiquitination, which is depending on E3 ubiquitin ligase CHIP. At last, MK-8776 showed a significant tumor-suppressive effect of KBM5^T315I cell in xenograft tumor models. Taking together, these findings suggest that targeting Chk1 may overcome TKIs resistance for the treatment of CML.

Indole-3-carbinol induces apoptosis of chronic myelogenous leukemia cells through suppression of STAT5 and Akt signaling pathways

Signal transducer and activator of transcription 5 and Akt pathways, implicated in signaling transduction downstream of BCR-ABL, play critical roles in the pathogenesis of chronic myeloid leukemia. Therefore, idenication of novel compounds that modulate the activity of such pathways could be a new approach in the treatment of chronic myeloid leukemia. Previous studies have demonstrated that indole-3-carbinol inhibits the proliferation and induces apoptosis of various tumor cells. However, its anticancer activity against chronic myeloid leukemia cells and the underlying mechanism remain unclear. Our data revealed that indole-3-carbinol promoted mitochondrial apoptosis of chronic myeloid leukemia-derived K562 cells, as evidenced by the activation of caspases and poly (ADP-ribose) polymerase cleavage. Treatment with indole-3-carbinol was found to be associated with a decrease in the cellular levels of phospho-Akt and phospho-signal transducer and activator of transcription 5. In addition, real-time polymerase chain reaction analysis showed that the downregulation of genes is regulated by Akt and signal transducer and activator of transcription 5. We also found that treatment with indole-3-carbinol resulted in the activation of the p38 mitogen-activated protein kinase and reduced expression of human telomerase and c-Myc. Collectively, these results demonstrate that the oncogenic signal transducer and activator of transcription 5/Akt pathway is a cellular target for indole-3-carbinol in chronic myeloid leukemia cells. Thus, this clinically tested natural compound can be a potential candidate in the treatment of chronic myeloid leukemia following confirmation with clinical studies.

Platinum pyrithione induces apoptosis in chronic myeloid leukemia cells resistant to imatinib via DUB inhibition-dependent caspase activation and Bcr-Abl downregulation

Chronic myelogenous leukemia (CML) is characterized by the chimeric tyrosine kinase Bcr-Abl. T315I Bcr-Abl is the most notorious point mutation to elicit acquired resistance to imatinib (IM), leading to poor prognosis. Therefore, it is urgent to search for additional approaches and targeting strategies to overcome IM resistance. We recently reported that platinum pyrithione (PtPT) potently inhibits the ubiquitin–proteasome system (UPS) via targeting the 26 S proteasome-associated deubiquitinases (DUBs), without effecting on the 20 S proteasome. Here we further report that (i) PtPT induces apoptosis in Bcr-Abl wild-type and Bcr-Abl-T315I mutation cells including the primary mononuclear cells from CML patients clinically resistant to IM, as well as inhibits the growth of IM-resistant Bcr-Abl-T315I xenografts in vivo; (ii) PtPT downregulates Bcr-Abl level through restraining Bcr-Abl transcription, and decreasing Bcr-Abl protein mediated by DUBs inhibition-induced caspase activation; (iii) UPS inhibition is required for PtPT-induced caspase activation and cell apoptosis. These findings support that PtPT overcomes IM resistance through both Bcr-Abl-dependent and -independent mechanisms. We conclude that PtPT can be a lead compound for further drug development to overcome imatinib resistance in CML patients.

Dynamical models of mutated chronic myelogenous leukemia cells for a post-imatinib treatment scenario: Response to dasatinib or nilotinib therapy

Targeted inhibition of the oncogenic BCR-ABL1 fusion protein using the ABL1 tyrosine kinase inhibitor imatinib has become standard therapy for chronic myelogenous leukemia (CML), with most patients reaching total and durable remission. However, a significant fraction of patients develop resistance, commonly due to mutated ABL1 kinase domains. This motivated development of second-generation drugs with broadened or altered protein kinase selectivity profiles, including dasatinib and nilotinib. Imatinib-resistant patients undergoing treatment with second-line drugs typically develop resistance to them, but dynamic and clonal properties of this response differ. Shared, however, is the observation of clonal competition, reflected in patterns of successive dominance of individual clones. We present three deterministic mathematical models to study the origins of clinically observed dynamics. Each model is a system of coupled first-order differential equations, considering populations of three mutated active stem cell strains and three associated pools of differentiated cells; two models allow for activation of quiescent stem cells. Each approach is distinguished by the way proliferation rates of the primary stem cell reservoir are modulated. Previous studies have concentrated on simulating the response of wild-type leukemic cells to imatinib administration; our focus is on modelling the time dependence of imatinib-resistant clones upon subsequent exposure to dasatinib or nilotinib. Performance of the three computational schemes to reproduce selected CML patient profiles is assessed. While some simple cases can be approximated by a basic design that does not invoke quiescence, others are more complex and require involvement of non-cycling stem cells for reproduction. We implement a new feedback mechanism for regulation of coupling between cycling and non-cycling stem cell reservoirs that depends on total cell populations. A bifurcation landscape analysis is also performed for solutions to the basic ansatz. Computational models reproducing patient data illustrate potential dynamic mechanisms that may guide optimization of therapy of drug resistant CML.

Biochemical and chemical characterization of Cynara cardunculus L. extract and its potential use as co-adjuvant therapy of chronic myeloid leukemia

ETHNOPHARMACOLOGICAL RELEVANCE

Ancient mediterranean diet was characterized by consuming the spontaneous forms of Cynara cardunculus L. (CCL), commonly called artichoke. Cultivated and/or spontaneous forms of CC studies have demonstrated that methanol extract of CCL flower and/or cynaropicrin showed remarkable anti-proliferative activity in vitro models of leukocyte cancer cell.

AIM OF THE STUDY

Chronic myeloid leukemia (CML) is associated with a reciprocal translocation of the long arms of chromosomes 9 and 22 generating the BCR/ABL fusion gene, translated in the p210^BCR/ABL oncoprotein kinase. This chimeric protein is the target of a kinase inhibitor, imatinib, but the development of mutations in the ABL kinase domain resulting in drug resistance and several approaches to overcoming resistance have been study. In this concern, we investigated the effect of CCL extract on human K562 CML and K562 imatinib resistant (IMAR) cell proliferation and on p210^BCR/ABL expression.

MATERIALS AND METHODS

Chemical characterization of the CCL extracts was performed by GC/MS analysis and semipreparative RP-HPLC chromatography. Structural characterization of compounds was assessed by ¹H-¹³C NMR and LC/MS analysis. The effects of CCL extracts on the proliferation of K562 CML human cell line and K562 IMAR were screened by MTT assay. The p210^BCR/ABL mRNA and protein expressions were analyzed by qRT-PCR and Western blot techniques respectively.

RESULTS

We demonstrate that CCL extract affect cell viability of both K562 CML human cell line and K562 IMAR. The biocomponents of CCL were chemical characterized and we identify cynaropicrin and its deacyl derivative having the capability to down-regulate the p210^BCR/ABL oncoprotein.

CONCLUSIONS

Our study suggests that the use of those molecules could represent a novel and promising strategy to potentiate the ability of imatinib or of its analogues to induce cancer growth arrest in CML and to delay or overcome the resistance of CML to chemotherapy.

Induction of p53 suppresses chronic myeloid leukemia

Chronic myeloid leukemia (CML) is characterized by the chromosomal translocation 9;22, known as the Philadelphia chromosome (Ph), which produces the BCR-ABL fusion tyrosine kinase. Although well-managed by BCR-ABL tyrosine kinase inhibitors (TKIs), treatment fails to eliminate Ph + primitive progenitors, and cessation of therapy frequently results in relapse. The p53 protein is an important regulator of cell cycle and apoptosis. The small molecules MI-219 target the interaction between p53 and its negative regulator HDM2, leading to its stabilization and activation. We show that treatment with MI-219 reduced the number of CML cells in both in vitro and in vivo settings but not that of normal primitive progenitors, and activated different gene signatures in CML potentially explaining the differential impact of this agent on each population. Our data suggest that a p53-activating agent may be an effective approach in the management and potential operational cure of CML.

Nickel pyrithione induces apoptosis in chronic myeloid leukemia cells resistant to imatinib via both Bcr/Abl-dependent and Bcr/Abl-independent mechanisms

BACKGROUND

Acquired imatinib (IM) resistance is frequently characterized by Bcr-Abl mutations that affect IM binding and kinase inhibition in patients with chronic myelogenous leukemia (CML). Bcr-Abl-T315I mutation is the predominant mechanism of the acquired resistance to IM. Therefore, it is urgent to search for additional approaches and targeting strategies to overcome IM resistance. We recently reported that nickel pyrithione (NiPT) potently inhibits the ubiquitin proteasome system via targeting the 19S proteasome-associated deubiquitinases (UCHL5 and USP14), without effecting on the 20S proteasome. In this present study, we investigated the effect of NiPT, a novel proteasomal deubiquitinase inhibitor, on cell survival or apoptosis in CML cells bearing Bcr-Abl-T315I or wild-type Bcr-Abl.

METHODS

Cell viability was examined by MTS assay and trypan blue exclusion staining assay in KBM5, KBM5R, K562, BaF3-p210-WT, BaF3-p210-T315I cells, and CML patients' bone marrow samples treated with NiPT. Cell apoptosis in CML cells was detected with Annexin V-FITC/PI and rhodamine-123 staining followed by fluorescence microscopy and flow cytometry and with western blot analyses for apoptosis-associated proteins. Expression levels of Bcr-Abl in CML cells were analyzed by using western blotting and real-time PCR. The 20S proteasome peptidase activity was measured using specific fluorogenic substrate. Active-site-directed labeling of proteasomal DUBs, as well as the phosphorylation of USP14 was used for evaluating the inhibition of the DUBs activity by NiPT. Mouse xenograft models of KBM5 and KBM5R cells were analyzed, and Bcr-Abl-related proteins and protein biomarkers related to proliferation, differentiation, and adhesion in tumor tissues were detected by western blots and/or immunohistological analyses.

RESULTS

NiPT induced apoptosis in CML cells and inhibited the growth of IM-resistant Bcr-Abl-T315I xenografts in nude mice. Mechanistically, NiPT induced decreases in Bcr-Abl proteins, which were associated with downregulation of Bcr-Abl transcription and with the cleavage of Bcr-Abl protein by activated caspases. NiPT-induced ubiquitin proteasome system inhibition induced caspase activation in both IM-resistant and IM-sensitive CML cells, and the caspase activation was required for NiPT-induced Bcr-Abl downregulation and apoptotic cell death.

CONCLUSIONS

These findings support that NiPT can overcome IM resistance through both Bcr-Abl-dependent and Bcr-Abl-independent mechanisms, providing potentially a new option for CML treatment.

Aurora A Kinase Inhibitor AKI603 Induces Cellular Senescence in Chronic Myeloid Leukemia Cells Harboring T315I Mutation

The emergence of resistance to imatinib mediated by mutations in the BCR-ABL has become a major challenge in the treatment of chronic myeloid leukemia (CML). Alternative therapeutic strategies to override imatinib-resistant CML are urgently needed. In this study, we investigated the effect of AKI603, a novel small molecule inhibitor of Aurora kinase A (AurA) to overcome resistance mediated by BCR-ABL-T315I mutation. Our results showed that AKI603 exhibited strong anti-proliferative activity in leukemic cells. AKI603 inhibited cell proliferation and colony formation capacities in imatinib-resistant CML cells by inducing cell cycle arrest with polyploidy accumulation. Surprisingly, inhibition of AurA by AKI603 induced leukemia cell senescence in both BCR-ABL wild type and T315I mutation cells. Furthermore, the induction of senescence was associated with enhancing reactive oxygen species (ROS) level. Moreover, the anti-tumor effect of AKI603 was proved in the BALB/c nude mice KBM5-T315I xenograft model. Taken together, our data demonstrate that the small molecule AurA inhibitor AKI603 may be used to overcome drug resistance induced by BCR-ABL-T315I mutation in CML.

Histone deacetylase inhibitor pracinostat in doublet therapy: a unique strategy to improve therapeutic efficacy and to tackle herculean cancer chemoresistance

Context Histone deacetylase inhibitors (HDACi) have shown promising results in neurodegeneration and cancer. Hydroxamate HDACi, including vorinostat, have shown encouraging results in haematological malignancies, but the poor pharmacokinetic of these inhibitors leads to insufficient tumour concentration limiting their application against solid malignancies. Objective This article deals with novel HDAC inhibitor pracinostat (SB939) and delineates its therapeutic role in solid and haematological malignancies. The article provides rigorous details about the underlying molecular mechanisms modulated by pracinostat to exert cytotoxic effect. The article further highlights the doublet therapy that may be used to tackle monotonous cancer chemoresistance. Methods Both old and the latest literature on pracinostat was retrieved from diverse sources, such as PubMed, Science Direct, Springer Link, general Google search using both pracinostat and SB939 keywords in various ways: after thorough evaluation the topic which can fulfil the current gap was chosen. Results Pracinostat shows potent anticancer activity against both solid and haematological malignancies compared to the FDA-approved drug vorinostat. This marvellous inhibitor has better physicochemical, pharmaceutical and pharmacokinetic properties than the defined inhibitor vorinostat. Pracinostat has  >100-fold more affinity towards HDACs compared to other zinc-dependent metalloenzymes and shows maximum efficacy when used in doublet therapy. Conclusion Pracinostat shows potent anticancer activity even against therapeutically challenging cancers when used in doublet therapy. However, the triplet combination studies of the defined inhibitor that may prove even more beneficial are still undone, emphasizing the desperate need of further research in the defined gap.

Combination therapy with copanlisib and ABL tyrosine kinase inhibitors against Philadelphia chromosome-positive resistant cells

ABL tyrosine kinase inhibitor (TKI) therapy has improved the survival of patients with Philadelphia (Ph) chromosome-positive leukemia. However, ABL TKIs cannot eradicate leukemia stem cells. Therefore, new therapeutic approaches for Ph-positive leukemia are needed. Aberrant activation of phosphoinositide 3-kinase (PI3K) signaling is important for the initiation and maintenance of human cancers. Copanlisib (BAY80-6946) is a potent inhibitor of PI3Kα and PI3K-δ. Here we investigated the efficacy of combination therapy of copanlisib with an ABL TKI (imatinib, nilotinib, or ponatinib) using BCR-ABL-positive cells. Although the effects of the ABL TKI treatment were reduced in the presence of the feeder cell line, HS-5, copanlisib inhibited cell growth. Upon combining ABL TKI and copanlisib, cell growth was reduced. Ponatinib and copanlisib combined therapy reduced tumor volume and increased survival in mouse allograft models, respectively. These results indicate that the PI3Kα and -δ inhibitors overcame the chemoprotective effects of the feeder cells and enhanced ABL TKI cytotoxicity. Thus, co-treatment with ABL TKI and copanlisib may be a powerful strategy against ABL TKI-resistant cells, including those harboring the related T315I mutation.

Impact of ABCB1 1236C > T-2677G > T-3435C > T polymorphisms on the anti-proliferative activity of imatinib, nilotinib, dasatinib and ponatinib

Overexpression of ABCB1 (also called P-glycoprotein) confers resistance to multiple anticancer drugs, including tyrosine kinase inhibitors (TKIs). Several ABCB1 single nucleotide polymorphisms affect the transporter activity. The most common ABCB1 variants are 1236C > T, 2677G > T, 3435C > T and have been associated with clinical response to imatinib in chronic myelogenous leukaemia (CML) in some studies. We evaluated the impact of these polymorphisms on the anti-proliferative effect and the intracellular accumulation of TKIs (imatinib, nilotinib, dasatinib and ponatinib) in transfected HEK293 and K562 cells. ABCB1 overexpression increased the resistance of cells to doxorubicin, vinblastine and TKIs. Imatinib anti-proliferative effect and accumulation were decreased to a larger extent in cells expressing the ABCB1 wild-type protein compared with the 1236T-2677T-3435T variant relatively to control cells. By contrast, ABCB1 polymorphisms influenced the activity of nilotinib, dasatinib and ponatinib to a much lesser extent. In conclusion, our data suggest that wild-type ABCB1 exports imatinib more efficiently than the 1236T-2677T-3435T variant protein, providing a molecular basis for the reported association between ABCB1 polymorphisms and the response to imatinib in CML. Our results also point to a weaker impact of ABCB1 polymorphisms on the activity of nilotinib, dasatinib and ponatinib.

Effect of STAT3 inhibitor in chronic myeloid leukemia associated signaling pathway: a mathematical modeling, simulation and systems biology study

Chronic myeloid leukemia (CML) is a hematopoietic stem-cell disorder which proliferates due to abnormal growth of basophil cells. Several proangiogenic molecules have been reported to be associated in CML progression, including the hepatocyte growth factor (HGF). However, detail mechanism about the cellular distribution and function of HGF in CML is yet to be revealed. The proliferation of hematopoietic cells are regulated by some of the growth factors like interleukin 3 (IL-3), IL-6, erythropoietin, thrombopoietin, etc. In this study IL-6 pathways have been taken into consideration which induces JAK/STAT and MAPK pathways to decipher the CML progression stages. An attempt has been made to model these pathways with the help of ordinary differential equations (ODEs) and estimating unknown parameters through fminsearch optimization algorithm. Some of the specific component like STAT3, of the pathway has been analyzed in detail and their role in CML progression has been elucidated. The roles of STAT3 inhibitors into the treatment of CML have been thoroughly studied and optimum concentration of the inhibitors have been predicted.

Pharmacokinetics and excretion of (14)C-omacetaxine in patients with advanced solid tumors

Background Omacetaxine mepesuccinate is indicated in adults with chronic myeloid leukemia resistant and/or intolerant to ≥ 2 tyrosine kinase inhibitor treatments. This phase I study assessed the disposition, elimination, and safety of (14)C-omacetaxine in patients with solid tumors. Methods The study comprised a 7-days pharmacokinetic assessment followed by a treatment period of ≤ six 28-days cycles. A single subcutaneous dose of 1.25 mg/m(2) (14)C-omacetaxine was administered to six patients. Blood, urine, and feces were collected through 168 h or until radioactivity excreted within 24 h was <1 % of the dose. Total radioactivity (TRA) was measured in all matrices and concentrations of omacetaxine, 4'-desmethylhomoharringtonine (4'-DMHHT), and cephalotaxine were measured in plasma and urine. For each treatment cycle, patients received 1.25 mg/m(2) omacetaxine twice daily for 7 days. Results Mean TRA recovered was approximately 81 % of the dose, with approximately half of the radioactivity recovered in feces and half in urine. Approximately 20 % of the dose was excreted unchanged in urine; cephalotaxine (0.4 % of dose) and 4' DMHHT (9 %) were also present. Plasma concentrations of TRA were higher than the sum of omacetaxine and known metabolites, suggesting the presence of other (14)C-omacetaxine-derived compounds. Fatigue and anemia were common, consistent with the known toxicity profile of omacetaxine. Conclusion Renal and hepatic processes contribute to the elimination of (14)C-omacetaxine-derived radioactivity in cancer patients. In addition to omacetaxine and its known metabolites, other (14)C-omacetaxine-derived materials appear to be present in plasma and urine. Omacetaxine was adequately tolerated, with no new safety signals.

Interferon-α Revisited: Individualized Treatment Management Eased the Selective Pressure of Tyrosine Kinase Inhibitors on BCR-ABL1 Mutations Resulting in a Molecular Response in High-Risk CML Patients

Bone marrow transplantation or ponatinib treatment are currently recommended strategies for management of patients with chronic myeloid leukemia (CML) harboring the T315I mutation and compound or polyclonal mutations. However, in some individual cases, these treatment scenarios cannot be applied. We used an alternative treatment strategy with interferon-α (IFN-α) given solo, sequentially or together with TKI in a group of 6 cases of high risk CML patients, assuming that the TKI-independent mechanism of action may lead to mutant clone repression. IFN-α based individualized therapy decreases of T315I or compound mutations to undetectable levels as assessed by next-generation deep sequencing, which was associated with a molecular response in 4/6 patients. Based on the observed results from immune profiling, we assumed that the principal mechanism leading to the success of the treatment was the immune activation induced with dasatinib pre-treatment followed by restoration of immunological surveillance after application of IFN-α therapy. Moreover, we showed that sensitive measurement of mutated BCR-ABL1 transcript levels augments the safety of this individualized treatment strategy.

Single nucleotide polymorphisms in apoptosis pathway are associated with response to imatinib therapy in chronic myeloid leukemia

Background

The mechanism of action of imatinib is known to involve the Fas-mediated apoptosis pathway. Consequently inter-individual variations in this apoptosis pathway might be associated with imatinib response or resistance.

Methods

This study attempted to focus on eight genotypes in the apoptosis pathway including FAS (rs1800682, rs2229521, rs2234767 and rs2234978), FASLG (rs763110), CASP10 (rs13006529), and APAF1 (rs1439123, rs2288713) and analyzed their association with treatment outcomes including molecular response with 4.5 log reduction (MR4.5), following imatinib therapy in 187 Korean CML patients.

Results

The GG/GA genotype in FAS (rs2234767) showed a higher rate of MR4.5 than the AA genotype (at 5 years 59.7 vs 37.4 %, p = 0.013). Using a bootstrap procedure for internal validation we confirmed that FAS (rs2234767) correlates with MR4.5 (p = 0.050). Multivariate analysis confirmed that the FAS genotype (rs2234767) is an independent surrogate for MR4.5 (p = 0.019, HR 0.43, 95 % CI [0.22–0.87]).

Conclusions

The Fas/FasL signaling pathway may represent the major pathway that mediates apoptosis in CML treated with imatinib. SNP markers in the apoptosis pathway including FAS genotype (rs2234767) can be potential surrogates for predicting deeper molecular response after imatinib therapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0837-5) contains supplementary material, which is available to authorized users.

Metabolite profiling of 14C-omacetaxine mepesuccinate in plasma and excreta of cancer patients

Omacetaxine mepesuccinate (hereafter referred to as omacetaxine) is a protein translation inhibitor approved by the US Food and Drug Administration for adult patients with chronic myeloid leukemia with resistance and/or intolerance to two or more tyrosine kinase inhibitors. The objective was to investigate the metabolite profile of omacetaxine in plasma, urine and faeces samples collected up to 72 h after a single 1.25-mg/m² subcutaneous dose of ¹⁴C-omacetaxine in cancer patients. High-performance liquid chromatography mass spectrometry (MS) (high resolution) in combination with off-line radioactivity detection was used for metabolite identification. In total, six metabolites of omacetaxine were detected. The reactions represented were mepesuccinate ester hydrolysis, methyl ester hydrolysis, pyrocatechol conversion from the 1,3-dioxole ring. Unchanged omacetaxine was the most prominent omacetaxine-related compound in plasma. In urine, unchanged omacetaxine was also dominant, together with 4'-DMHHT. In feces very little unchanged omacetaxine was found and the pyrocatechol metabolite of omacetaxine, M534 and 4'-desmethyl homoharringtonine (4'-DMHHT) was the most abundant metabolites. Omacetaxine was extensively metabolized, with subsequent renal and hepatic elimination of the metabolites. The low levels of the metabolites found in plasma indicate that the metabolites are unlikely to contribute materially to the efficacy and/or toxicity of omacetaxine.