Design, in silico Evaluation, and Determination of Antitumor Activity of Potential Inhibitors Against Protein Kinases: Application to BCR-ABL Tyrosine Kinase.

Despite significant progress made over the past two decades in the treatment of chronic myeloid leukemia (CML), there is still an unmet need for effective and safe agents to treat patients with resistance and intolerance to the drugs used in clinic. In this work, we designed 2-arylaminopyrimidine amides of isoxazole-3-carboxylic acid, assessed in silico their inhibitory potential against Bcr-Abl tyrosine kinase, and determined their antitumor activity in K562 (CML), HL-60 (acute promyelocytic leukemia), and HeLa (cervical cancer) cells. Based on the analysis of computational and experimental data, three compounds with the antitumor activity against K562 and HL-60 cells were identified. The lead compound efficiently suppressed the growth of these cells, as evidenced by the low IC50 values of 2.8 ± 0.8 µM (K562) and 3.5 ± 0.2 µM (HL-60). The obtained compounds represent promising basic structures for the design of novel, effective, and safe anticancer drugs able to inhibit the catalytic activity of Bcr-Abl kinase by blocking the ATP-binding site of the enzyme.

Regulation of Cell Cycle Progression through RB Phosphorylation by Nilotinib and AT-9283 in Human Melanoma A375P Cells.

BCR-ABL tyrosine kinase inhibitors are commonly employed for the treatment of chronic myeloid leukemia, yet their impact on human malignant melanoma remains uncertain. In this study, we delved into the underlying mechanisms of specific BCR-ABL tyrosine kinase inhibitors (imatinib, nilotinib, ZM-306416, and AT-9283) in human melanoma A375P cells. We first evaluated the influence of these inhibitors on cell growth using cell proliferation and wound-healing assays. Subsequently, we scrutinized cell cycle regulation in drug-treated A375P cells using flow cytometry and Western blot assays. Notably, imatinib, nilotinib, ZM-306416, and AT-9283 significantly reduced cell proliferation and migration in A375P cells. In particular, nilotinib and AT-9283 impeded the G1/S transition of the cell cycle by down-regulating cell cycle-associated proteins, including cyclin E, cyclin A, and CDK2. Moreover, these inhibitors reduced RB phosphorylation, subsequently inhibiting E2F transcriptional activity. Consequently, the expression of the E2F target genes (CCNA2, CCNE1, POLA1, and TK-1) was markedly suppressed in nilotinib and AT9283-treated A375P cells. In summary, our findings suggest that BCR-ABL tyrosine kinase inhibitors may regulate the G1-to-S transition in human melanoma A375P cells by modulating the RB-E2F complex.

Sex-specific incidence of hepatitis B virus flares among Bcr-Abl tyrosine kinase inhibitor users in Taiwan.

BACKGROUND: The use of Bcr-Abl TKI was found to be associated with hepatitis B (HBV) flares, with a more profound risk observed in females. This study was conducted to characterize the clinical features of patients with HBV flare among Bcr-Abl TKI users, to estimate sex-specific incidence rates of HBV flare, and to evaluate potential cumulative effect of Bcr-Abl TKI. METHODS: Bcr-Abl TKI users with chronic HBV infection were identified from Taiwan's National Health Insurance database. The HBV flare cases were identified within the cohort. Incidence rates of HBV flare between men and women were assessed. Nested case-control analysis was used to evaluate the cumulative effect of Bcr-Abl TKI use on HBV flare. RESULTS: Among 415 patients with chronic HBV infection treated with Bcr-Abl TKI from 2005 through 2018, 45 flare cases (28 males and 17 females) were identified. Days between Bcr-Abl TKI initiation and HBV flare was 319 days in women compared to 610 days in men. 66.7% of the flares occurred during TKI therapy. Twelve of the 45 patients died, half of them died around 6 months after hepatitis B flare. Incidence rates of HBV flare were 2.34 and 3.33 per 100 person-years in males and females, respectively. Higher incidence was observed among patients with chronic myeloid leukemia. Cumulative effect of Bcr-Abl TKI on HBV flare was not observed. CONCLUSION: Approximately 10% of HBV carriers who used Bcr-Abl TKI experienced HBV flare in Taiwan. The risk was higher in women and among patients with chronic myeloid leukemia.

Adverse Reaction Profiles Related to Gastrointestinal Bleeding Events Associated with BCR-ABL Tyrosine Kinase Inhibitors.

Background and Objectives: The aim of this study is to investigate the characteristics of gastrointestinal bleeding events associated with BCR-ABL tyrosine kinase inhibitor (TKI) treatment, using the reporting odds ratio (ROR) of the adverse event reports submitted to the Japanese Adverse Drug Event Report database between 2004 and 2020, and to examine the number of reported TKI-related gastrointestinal bleeding cases according to sex and age, as well as the actual number of TKI prescriptions issued in Japan. Materials and Methods: The RORs and 95% confidence intervals (CIs) of gastrointestinal bleeding events related to TKIs were calculated using the data of the 595,121 included cases. Results: Significant gastrointestinal bleeding events were detected for dasatinib (crude ROR: 4.47, 95% CI: 3.77-5.28) and imatinib (crude ROR: 1.22, 95% CI: 1.01-1.46). In multiple logistic regression analyses, significant gastrointestinal bleeding events were detected for dasatinib (adjusted ROR: 8.02, 95% CI: 5.75-10.2), imatinib (adjusted ROR: 1.81, 95% CI: 1.2-2.72), age (≥60 years, adjusted ROR: 2.22, 95% CI: 2.1-2.36), reporting year (adjusted ROR: 1.04, 95% CI: 1.04-1.05), and male sex (adjusted ROR: 1.47, 95% CI: 1.37-1.57). Interaction analysis revealed that the association of gastrointestinal bleeding with dasatinib was affected by age (≥60 years) and sex (female), with the number and proportion of dasatinib-related gastrointestinal bleeding cases increasing among those aged ≥60 years. Conclusions: Specific TKIs and patient characteristics were associated with gastrointestinal bleeding. Our results aid the prompt identification and treatment of TKI-related gastrointestinal bleeding.

[Chronic myeloid leukemia presenting with marked eosinophilia].

An 80-year-old female with fever, edema in the lower extremities, and marked eosinophilia was referred to our hospital. Based on the presence of the Philadelphia chromosome, she was diagnosed with chronic myeloid leukemia (CML). Although imatinib induced a complete cytogenetic response (CCyR), CML relapsed after 28 months of starting it. A CCyR was achieved again by nilotinib but was lost after about 14 months. Only transient response occurred to dasatinib, and the patient died. At relapse, neutrophilia was more predominant than eosinophilia. We reviewed 6 patients with CML whose eosinophil rate in the peripheral blood was >50%. Most patients were males with palpable splenomegaly and had cardiac disorders, peripheral vascular disease, or pleural effusion. Typically, CML causes neutrophil-predominant leukocytosis. However, a subgroup of CML with marked eosinophilia resembles chronic eosinophilic leukemia or idiopathic hypereosinophilic syndrome.

Association between insurance status at diagnosis and overall survival in chronic myeloid leukemia: A population-based study.

BACKGROUND: Chronic myeloid leukemia (CML) can be treated effectively with tyrosine kinase inhibitor therapy directed at BCR-ABL, but access to care, medication cost, and adherence may be barriers to treatment. This study was designed to determine whether the insurance status at diagnosis influences CML patient outcomes. METHODS: The Surveillance, Epidemiology, and End Results database was used to identify 5784 patients, aged 15 years or older, who were diagnosed with CML between 2007 and 2012 and whose insurance status was documented at diagnosis. The primary outcome was 5-year overall survival (OS). Covariates of interest included the age at diagnosis, race, ethnicity, sex, county-level socioeconomic status, and marital status. OS was evaluated with a log-rank test and Kaplan-Meier estimates. RESULTS: Among patients aged 15 to 64 years, insurance status was associated with OS (P < .001): being uninsured or having Medicaid was associated with worse 5-year OS in comparison with being insured (uninsured patients, 72.7%; Medicaid patients, 73.1%; insured patients, 86.6%). For patients who were 65 years old or older, insurance had less of an impact on OS (P = .07), with similar 5-year OS rates for patients with Medicaid and those with other insurance (40.2% vs 43.4%). In a multivariate analysis of patients aged 15 to 64 years, both uninsured patients (hazard ratio [HR], 1.93; P < .001) and Medicaid patients (HR, 1.83; P < .001) had an increased hazard of death in comparison with insured patients; patients younger than 40 years, female patients, and married patients also had a lower hazard of death. CONCLUSION: These findings suggest that CML patients under the age of 65 years who are uninsured or have Medicaid have significantly worse survival than patients with other insurance coverage. Cancer 2017;123:2561-69. © 2017 American Cancer Society.

Targeting of the BLT2 in chronic myeloid leukemia inhibits leukemia stem/progenitor cell function.

Imatinib, a tyrosine kinase inhibitor (TKI) has significantly improved clinical outcome for chronic myeloid leukemia (CML) patients. However, patients develop resistance when the disease progresses to the blast phase (BP) and the mechanisms are not well understood. Here we show that BCR-ABL activates BLT2 in hematopoietic stem/progenitor cells to promote leukemogenesis and this involves the p53 signaling pathway. Compared to normal bone marrow (NBM), the mRNA and protein levels of BLT2 are significantly increased in BP-CML CD34(+) stem/progenitor cells. This is correlated with increasing BCR-ABL expression. In contrast, knockdown of BCR-ABL or inhibition of its tyrosine kinase activity decreases Blt2 protein level. BLT2 inhibition induces apoptosis, inhibits proliferation, colony formation and self-renewal capacity of CD34(+) cells from TKI-resistant BP-CML patients. Importantly, the inhibitory effects of BCR-ABL TKI on CML stem/progenitor cells are further enhanced upon combination with BLT2 inhibition. We further show that BLT2 activation selectively suppresses p53 but not Wnt or BMP-mediated luciferase activity and transcription. Our results demonstrate that BLT2 is a novel pathway activated by BCR-ABL and critically involved in the resistance of BP-CML CD34(+) stem/progenitors to TKIs treatment. Our findings suggest that BLT2 and p53 can serve as therapeutic targets for CML treatment.

[Chronic myelogenous leukemia: diagnosis and treatment]. / A krónikus myeloid leukaemia korszeru diagnosztikája és kezelése.

Chronic myelogenous leukemia is a clonal myeloproliferative neoplasm caused by reciprocal translocation involving chromosomes 9 and 22 resulting in the expression of a constitutively activated BCR-ABL1 tyrosine kinase that leads to the malignant transformation of the hematopoietic stem cells. The condition was previously known as a relentlessly progressive disease, but the treatment was revolutionalized by the efficacy of tyrosine kinase inhibitors. Therapeutic success is thus currently determined by the depth of molecular response achieved on therapy. Multiple tyrosine kinase agents are available even for the first line treatment. This guideline summarizes current focal points of the treatment of chronic myelogenous leukemia specific to Hungary and provides definitions for optimal molecular responses in this condition. Orv. Hetil., 2016, 157(37), 1459-1468.

Risk and impact of tuberculosis in patients with chronic myeloid leukemia: a nationwide population-based study in Taiwan.

The relationship between chronic myeloid leukemia (CML) and tuberculosis (TB) has not been determined. We conducted a national survey including 1,082 CML patients identified from the Taiwan National Health Insurance database covering a period between 1998 and 2011; the matched non-exposed cohort included 10,820 subjects without CML that were matched for age, sex and comorbidities. The impact of TB was measured by the overall mortality, and the risk factors were identified by a multivariate Cox proportional hazards model. We found the risk of TB was higher in the CML cohort, with an adjusted hazard ratio (aHR) of 3.76 (p = 0.001) for both pulmonary (aHR 3.23, p < 0.001) and extrapulmonary (aHR 9.77, p = 0.001) TB. Specific risk factors were: aged ≥ 60 (aHR 3.24, p = 0.022), being male (aHR 13.49, p = 0.012), receiving stem cell transplantation (aHR 10.50, p = 0.001) and interferon-α therapy (aHR 3.34, p = 0.011). CML patients with TB had a higher mortality rate than those without (aHR 2.04, p = 0.043). We conclude that the incidence of TB is significantly higher in CML patients of male sex, aged ≥ 60, having received either stem cell transplantation or interferon-α treatment. Careful screening strategies for TB should be considered for CML patients with high risk of the infection.

Ponatinib: A new tyrosine kinase inhibitor for the treatment of chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia.

OBJECTIVE: To review the pharmacology, pharmacokinetics, clinical trials, adverse effects, and formulary considerations of ponatinib, a pan-tyrosine kinase inhibitor (TKI). DATA SOURCES: A literature search of articles published between January 1966 and June 2013 was performed using PubMed with the following search terms: ponatinib, AP24534, and Iclusig. ARIAD Pharmaceuticals, Inc, was contacted for unpublished information. Other sources included American Society of Hematology abstracts, the Food and Drug Administration Center for Drug Evaluation and Research Web site, and clinicaltrials.gov. STUDY SELECTION/DATA EXTRACTION: Included articles and abstracts were published in English and contain information about ponatinib, particularly in the treatment of chronic myeloid leukemia (CML) or Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL). DATA SYNTHESIS: Following the phase II PACE trial, ponatinib was approved for the treatment of patients with chronic-phase (CP), accelerated-phase (AP), or blast-phase (BP) CML or Ph+ ALL who have become intolerant or resistant to previous therapy. Unlike other BCR-ABL TKIs, ponatinib was designed to overcome the T315I mutation. At 15.3 months, 46% of patients with CP-CML achieved a complete cytogenetic response, and 34% achieved a major molecular response. Complete hematologic responses occurred in 47% of patients with AP-CML, 21% with BP-CML, and 34% with Ph+ ALL after 1 year. Severe toxicities included myelosuppression, hepatotoxicity, pancreatitis, and arterial thrombosis. CONCLUSIONS: Ponatinib is a potent TKI that can overcome several resistance mechanisms in previously treated patients with CML and Ph+ ALL. Ponatinib should be reserved for patients who have failed first-line therapy, have the T315I mutation, or have progressed.

In silico design and computational evaluation of novel 2-arylaminopyrimidine-based compounds as potential multi-targeted protein kinase inhibitors: application for the native and mutant (T315I) Bcr-Abl tyrosine kinase.

An integrated computational approach to drug discovery was used to identify novel potential inhibitors of the native and mutant (T315I) Bcr-Abl tyrosine kinase, the enzyme playing a key role in the pathogenesis of chronic myeloid leukemia (CML). This approach included i) design of chimeric molecules based on the 2-arylaminopyrimidine fragment, the main pharmacophore of the Abl kinase inhibitors imatinib and nilotinib used in the clinic for the CML treatment, ii) molecular docking of these compounds with the ATP-binding site of the native and mutant Abl kinase, iii) refinement of the ligand-binding poses by the quantum chemical method PM7, iv) molecular dynamics simulations of the ligand/Abl complexes, and v) prediction of the ligand/Abl binding affinity in terms of scoring functions of molecular docking, machine learning, quantum chemistry, and molecular dynamics. As a result, five top-ranking compounds able to effectively block the enzyme catalytic site were identified. According to the data obtained, these compounds exhibit close modes of binding to the Abl kinase active site that are mainly provided by hydrogen bonds and multiple van der Waals contacts. The identified compounds show high binding affinity to the native and mutant Abl kinase comparable with the one calculated for the FDA-approved kinase-targeted inhibitors imatinib, nilotinib, and ponatinib used in the calculations as a positive control. The results obtained testify to the predicted drug candidates against CML may serve as good scaffolds for the design of novel anticancer agents able to target the ATP-binding pocket of the native and mutant Abl kinase.Communicated by Ramaswamy H. Sarma.

In silico and in vitro evaluation of imatinib as an inhibitor for SARS-CoV-2.

The rapid geographic expansion of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the infectious agent of Coronavirus Disease 2019 (COVID-19) pandemic, poses an immediate need for potent drugs. Enveloped viruses infect the host cell by cellular membrane fusion, a crucial mechanism required for virus replication. The SARS-CoV-2 spike glycoprotein, due to its primary interaction with the human angiotensin-converting enzyme 2 (ACE2) cell-surface receptor, is considered a potential target for drug development. In this study, around 5,800 molecules were virtually screened using molecular docking. Five molecules were selected for in vitro experiments from those that reported docking scores lower than -6 kcal/mol. Imatinib, a Bcr-Abl tyrosine kinase inhibitor, showed maximum antiviral activity in Vero cells. We further investigated the interaction of imatinib, a compound under clinical trials for the treatment of COVID-19, with SARS-CoV-2 RBD, using in silico methods. Molecular dynamics simulations verified that imatinib interacts with RBD residues that are critical for ACE2 binding. This study also provides significant molecular insights on potential repurposable small-molecule drugs and chemical scaffolds for the development of novel drugs targeting the SARS-CoV-2 spike RBD.Communicated by Ramaswamy H. Sarma.

Retrospective analysis of chronic myeloid leukemia patients treated in the Department of Internal Medicine and Oncology, Semmelweis University, between 2003 and 2019 / Krónikus myeloid leukaemia miatt 2003 és 2019 között a Semmelweis Egyetem Belgyógyászati és Onkológiai Klinikáján kezelt betegek adatainak elemzése

Összefoglaló. Bevezetés: A krónikus myeloid leukaemia a diagnosztika fejlodésének és a tirozin-kináz-gátlók bevezetésének köszönhetoen az elmúlt évtizedekben kiváló prognózisú betegséggé vált. Célkituzés: A betegséggel kapcsolatos ismereteink nagy része klinikai vizsgálatokból származik, emiatt kiemelt szerepük van a nem szelektált beteganyagon végzett elemzéseknek. Módszer: Retrospektív elemzésünkben a Semmelweis Egyetem Belgyógyászati és Onkológiai Klinikáján 2003 és 2019 között tirozin-kináz-gátló kezelésben részesült betegek adatait tekintettük át. Eredmények: Klinikánkon összesen 88 beteg részesült terápiában, közülük 73 beteg az analízis idopontjában is kezelés alatt állt. A betegek 5 éves össztúlélése 86%, 5 éves progressziómentes túlélése 70% volt. 9 beteg halt meg, közülük 2 betegnél a halál oka a progrediáló alapbetegség volt. 38 betegnél volt szükség az elso vonalban terápiaváltásra, a váltás oka akkor elsosorban az elégtelen terápiás válasz volt. A késobbi terápiaváltásokra elsosorban intolerancia miatt került sor. Az elso vonalban a betegek több mint fele major molekuláris választ ért el, a jelenlegi kezelés mellett a betegek 85%-ánál major molekuláris választ detektáltunk. Megbeszélés: Adataink alapján az intézményünkben kezelt betegek túlélése és a betegek által elért terápiás válasz megfelel a nemzetközi adatoknak. Következtetés: Mivel nem válogatott beteganyagról van szó, a kapott eredmények pontosabb képet adhatnak a krónikus myeloid leukaemia tirozin-kináz-gátlóval történt kezelésének eredményeirol. Orv Hetil. 2021; 162(32): 1297-1302. INTRODUCTION: As a result of advances in diagnostic techniques and the introduction of tyrosine kinase inhibitors, the prognosis of chronic myeloid leukemia has improved over the last decades. OBJECTIVE: Most of our knowledge about chronic myeloid leukemia results from clinical trials, therefore data derived from non-selected patient population is substantial. METHOD: Data of chronic myeloid leukemia patients treated with tyrosine kinase inhibitors at the Department of Internal Medicine and Oncology, Semmelweis University, between 2003 and 2019 were analysed retrospectively. RESULTS: 88 patients received treatment, 73 patients were on therapy at the time of the analysis. Overall survival at 5 years was 86%, progression-free survival at 5 years was 70%. 9 patients died, 2 of them due to progressive disease. 38 patients needed 2nd line therapy, the main reason of treatment change was failure of therapy. Subsequent treatment modifications were conducted mostly because of intolerance. More than half of the patients on 1st line treatment reached major molecular response and 85% of the patients on treatment at the end of the analysis are in major molecular response. DISCUSSION: Based on our data, survival and therapeutic response of patients in our center are similar to the international results. CONCLUSION: This analysis provides real-world data about treatment results of chronic myeloid leukemia in the tyrosine kinase inhibitor era. Orv Hetil. 2021; 162(32): 1297-1302.

The Risk of Arterial Thrombosis in Patients With Chronic Myeloid Leukemia Treated With Second and Third Generation BCR-ABL Tyrosine Kinase Inhibitors May Be Explained by Their Impact on Endothelial Cells: An In-Vitro Study.

BCR-ABL tyrosine kinase inhibitors (TKIs) revolutionized the treatment of chronic myeloid leukemia, inducing deep molecular responses, largely improving patient survival and rendering treatment-free remission possible. However, three of the five BCR-ABL TKIs, dasatinib, nilotinib, and ponatinib, increase the risk of developing arterial thrombosis. Prior investigations reported that nilotinib and ponatinib affect the endothelium, but the mechanisms by which they exert their toxic effects are still unclear. The impact of dasatinib and bosutinib on endothelial cells has been poorly investigated. Here, we aimed to provide an in vitro homogenous evaluation of the effects of BCR-ABL TKIs on the endothelium, with a special focus on the type of cell death to elucidate the mechanisms responsible for the potential cytotoxic effects of BCR-ABL TKIs nilotinib and ponatinib on endothelial cells. We tested the five BCR-ABL TKIs at three concentrations on human umbilical venous endothelial cells (HUVECs). This study highlights the endothelial toxicity of ponatinib and provides insights about the mechanisms by which it affects endothelial cell viability. Ponatinib induced apoptosis and necrosis of HUVECs after 72 h. Dasatinib affected endothelial cells in vitro by inhibiting their proliferation and decreased wound closure as soon as 24 h of treatment and even at infra-therapeutic dose (0.005 µM). Comparatively, imatinib, nilotinib, and bosutinib had little impact on endothelial cells at therapeutic concentrations. They did not induce apoptosis nor necrosis, even after 72 h of treatment but they inhibited HUVEC proliferation. Overall, this study reports various effects of BCR-ABL TKIs on endothelial cells and suggests that ponatinib and dasatinib induce arterial thrombosis through endothelial dysfunction.

Novel Therapies in the Treatment of Adult Acute Lymphoblastic Leukemia.

PURPOSE OF REVIEW: Acute lymphoblastic leukemia (ALL) is a rare hematologic malignancy. Advances in multi-agent chemotherapy have resulted in dramatic improvements in the number of pediatric cases that result in a cure; however, until recently, treatment options for older adults or patients with relapsed and refractory disease were extremely limited. This review seeks to describe in greater detail a number of emerging novel treatment modalities recently approved for this cancer. RECENT FINDINGS: In this review, we discuss a number of recently approved novel therapies for ALL, including new approaches with targeted tyrosine kinase inhibitors, novel immune-based therapies including the bispecific antibody blinatumomab and the antibody-drug conjugate inotuzumab ozogamicin, and the role of cellular therapeutics such as chimeric antigen receptor (CAR) T cells. We also discuss the impact that advances in diagnostics and disease classification and monitoring have had on treatment. A number of advances in ALL have resulted in dramatic changes to the treatment landscape and therapeutic options both at the time of diagnosis and in salvage. These findings are reshaping our treatment paradigms throughout the course of disease.

Dasatinib-induced pulmonary arterial hypertension complicated with scleroderma: a case report.

BACKGROUND: Although the BCR-ABL tyrosine kinase inhibitor dasatinib is a potent treatment for chronic myeloid leukaemia, it is associated with the risk of dasatinib-induced pulmonary arterial hypertension (DASA-PAH), for which predisposing factors have yet to be elucidated. However, animal studies have shown that dasatinib exacerbates pulmonary hypertension (PH) in rodent models of PH but not in controls, providing support for a two-hit theory of DASA-PAH pathophysiology. CASE SUMMARY: A 63-year-old man with worsening dyspnoea was diagnosed with severe DASA-PAH and concomitant scleroderma. He was successfully treated with discontinuation of dasatinib and administration of pulmonary vasodilators. DISCUSSION: Our case suggests that scleroderma may be a predisposing factor for the development of DASA-PAH, providing new insight into its pathophysiology.

Outcomes of unplanned tyrosine kinase inhibitor discontinuation in patients with chronic myeloid leukemia: retrospective analysis of real-world experience in a single institution.

OBJECTIVES: To explore real-world prognoses for tyrosine kinase inhibitor (TKI) discontinuation in chronic myeloid leukemia (CML) patients and the associated reasons for TKI discontinuation. METHODS: We investigated, using the medical records of 85 consecutive CML patients who received TKIs between December 2001 and August 2016 at our hospital, reasons for discontinuation, duration of TKI treatment before discontinuation, molecular response (MR) status at TKI discontinuation, treatment-free remission (TFR) duration, and overall survival after TKI discontinuation. RESULTS: TKI therapy was discontinued in 21 patients. The median treatment duration before discontinuation was 68.3 months. The response statuses at discontinuation were MR4 (n = 2), MR4.5 (n = 4), and ≥MR5 (n = 15). The reasons were pleural effusion (n = 5); requests for prolonged deep molecular response (DMR) (n = 4); ischemic heart disease, anemia, and economic problems (each, n = 3); renal dysfunction (n = 2); and hyperkalemia, diarrhea, dementia, asthma, and desire to get pregnant, (each, n = 1). All patients were alive with median follow-up period of 32.1 months. TFR was maintained in 14 patients, and the 2-year TFR proportion was 66.7%. Seven patients restarted TKI therapy and achieved MR4 within median of 3 months. The duration of TKI administration before discontinuation (≥ 70 months) was favored longer TFR durations. CONCLUSION: TKI was safely discontinued in clinical practice and yielded TFR rates similar to those observed in previous clinical trials, regardless of reason. Achievement of TFR significantly impacts patients' quality of life and should be considered in clinical practice.

Nilotinib-Induced Keratosis Pilaris.

Nilotinib is a second-generation Bcr-Abl tyrosine kinase inhibitor (TKI) that is approved for the treatment of imatinib-resistant chronic myeloid leukaemia expressing the Bcr-Abl mutation. Cutaneous adverse drug reactions occur more frequently in patients using this medication. We present a case of nilotinib-induced keratosis pilaris that did not have accompanying symptoms of alopecia or pruritus. Greater recognition of this association is needed so that appropriate treatment can be instituted to ensure a good oncologic outcome.

The sensitivity of chronic myeloid leukemia CD34 cells to Bcr-Abl tyrosine kinase inhibitors is modulated by ceramide levels.

Despite BCR-ABL tyrosine kinase inhibitors (TKIs) improved outcome of patients with chronic myeloid leukemia (CML), resistance still develops when progresses to blast phase (BP). The mechanisms underlying resistance to TKIs are not well understood. In this study, we analyzed ceramide levels in CD34 cells derived from BP-CML patients and healthy donor bone marrow (BM) using liquid chromatography mass spectrometry. We found that ceramide level was significantly lower in BP-CML CD34 compared with normal BM counterparts. BP-CML CD34 ceramide(low) were more resistant to BCR-ABL TKIs compared to BP-CML CD34 ceramide(normal). Both mRNA and proteins levels of sphingomyelin synthase 1 and 2 are lower in BP-CML CD34 ceramide(low) compared to normal BM CD34 cells, suggesting that these two ceramide synthesis enzymes maybe the mechanism of how ceramide level is suppressed. Importantly, up-regulation of cellular ceramide level induces apoptosis of multiple CML cell lines and BP-CML CD34 progenitors. Combination of BCR-ABL TKIs with ceramide analog is synergistic in targeting BP-CML 34 progenitors. Collectively, our work provides evidence that down-regulation of ceramide level is involved in the resistance of BP-CML CD34 progenitors to TKIs treatment. Targeting ceramide metabolism together with BCR-ABL inhibition makes it an attractive addition to the armamentarium in BP-CML treatment.

The tyrosine kinase inhibitor, nilotinib potentiates a prothrombotic state.

Tyrosine kinase inhibitors (TKI) such as imatinib, nilotinib and dasatinib are now established as highly effective frontline therapies for chronic myeloid leukaemia (CML). Disease control is achieved in the majority of patients and survival is excellent such that recent focus has been on toxicities of these agents. Cumulative data have reported an excess of serious vascular complications, including arterial thrombosis and peripheral arterial occlusive disease, in patients receiving nilotinib in comparison with other TKIs, with resultant interest in delineating the pathophysiology and implications for rationale cardiovascular risk modification. To address this issue, we studied the effects of imatinib, nilotinib and dasatinib on platelet function and thrombus formation in human and mouse models using in vitro, ex vivo and in vivo approaches. In vitro studies demonstrated that dasatinib and imatinib but not nilotinib inhibited ADP, CRP, and collagen-induced platelet aggregation and moreover, that nilotinib potentiated PAR-1-mediated alpha granule release. Pretreatment of wild-type C57BL/6 mice with nilotinib but not imatinib or dasatinib, significantly increased thrombus growth and stability, on type I collagen under ex vivo arterial flow conditions and increased thrombus growth and stability following FeCl3-induced vascular injury of mesenteric arterioles and carotid artery injury in vivo. Whole blood from nilotinib-treated CML patients, demonstrated increased platelet adhesion ex vivo under flow, increased plasma soluble P- and E-selectin, sICAM-1, sVCAM-1, TNF-alpha, IL-6 levels and endogenous thrombin potential (ETP) levels in vivo, despite being on daily low-dose aspirin. These results demonstrate that nilotinib can potentiate platelet and endothelial activation and platelet thrombus formation ex vivo and in vivo.