Chronic myeloid leukemia: a model for oncology

Association of the Trough, Peak/Trough Ratio of Imatinib, Pyridine-N-Oxide Imatinib and ABCG2 SNPs 34 G>A and SLCO1B3 334 T>G With Imatinib Response in Egyptian Chronic Myeloid Leukemia Patients

Imatinib mesylate (IM) is highly efficacious in the treatment of chronic myeloid leukemia (CML). Therapeutic drug monitoring and pharmacogenetic screening are affirmed for better management of IM therapy. The goal of this study was to gain a greater mechanistic understanding of the factors controlling variability in IM level and its relation to the response. One hundred and two patients with CML at chronic phase were recruited in this study. Blood samples were withdrawn at least 30 days after drug administration, and trough and peak concentrations of imatinib, N-des-methyl imatinib, and pyridine-N-oxide imatinib were determined by HPLC/MS/MS. Genetic polymorphism of the genes ABCG2 SNPs 34 G>A and 421C >A; ABCB1 SNPs 2677 G>A/T, 1236 C>T, 3435 C>T; SLCO1B3 SNPs 334 T>G and CYP3A5 were studied using PCR-RFLP technique. Our study presented significant higher trough IM (1,281 ± 578 ng/ml), lower Peak/Trough ratio, clearance (Cl), and elimination rate constant, k_e, among patients who achieved favorable responses (N = 64) than those for patients who suffered unfavorable response (N = 37). The P/T ratio was the only significant independent factor affecting response, as the P/T ratio increased by one, the risk of unfavorable response increased by more than double as compared to favorable response with 95% CI (1.28-3.92, P = 00.005). Moreover, like the results of IM, the trough concentration of Pyridine-N-oxide imatinib was significantly higher (P = 0.01) and its P/T ratio was significantly lower (P = 0.008) in patients achieved favorable response than those without. The wild GG genotype of the ABCG2.34 G>A gene was associated with favorable response (P = 0.01), lower Cl, K_e and high plasma IM trough level than both (AA+GA) genotypes. ABCG2.421C >A (CC) genotype had a significantly higher plasma peak of IM, N-des-methyl imatinib and higher C_ss. The GG and TG alleles of the SLCO1B3.334 T>G gene were significantly correlated to favorable response, while the wild allele TT was linked to unfavorable response (P = 0.03). In conclusion, the trough and P/ T ratio for both IM and Pyridine-N-oxide imatinib, in addition to Polymorphism of ABCG2 SNPs 34 G>A and SLCO1B3.334 T>G gene, is a good predictor for response of IM in CML Egyptian patients.

Frequency of hematologic malignancies in the population of Arica, Chile

Hematologic diseases are a heterogeneous group of malignancies that affect people worldwide such as leukemia, lymphoma and multiple myelomas. The aim of this study was to characterize the frequency of hematological diseases in the population of Arica, Chile (18°S, 70°W), between 2011 and 2014. A total of 108 cases of hematologic malignancies were registered at Dr. Juan Noé Crevani Regional Hospital in this period; 40 male and 52 female cases were included in this retrospective and descriptive analysis. The overall median age at diagnosis for hematological malignancies was 59 years (range, 17 to 96 years). The results indicated that the frequency of hematological diseases such as non-Hodgkin lymphoma and leukemia was not associated with sex, ethnicity and type of disease. However, in 2012 there was an increased number of cases of Hodgkin lymphoma compared with any other year in the study, whereas the number of multiple myeloma cases decreased between 2011 and 2014. No significant differences were observed among different types of disease, nor among the types of leukemia. However, when intervals of age were considered, it was revealed that patients >75 years had the highest incidence of hematological malignancies, mainly multiple myeloma, compared with other age groups. However, young adults were more commonly diagnosed with Hodgkin lymphoma than other disease types. A non-significant difference was observed in leukemia between 2011 and 2014 when sex was taken into consideration, in which the incidence rate was higher in females compared with males. Hodgkin lymphoma was most commonly at stage II and non-Hodgkin lymphoma was most commonly at stage IV. No significant differences were observed between the nodal and extranodal type, mixed cellularity and nodular sclerosis or in the morphology of non-Hodgkin lymphoma cell type. Overall, there was a decrease in the frequency of hematological malignancies between 2011 and 2014, but no significant differences were observed in males or females. This study provided for the first time the pattern and distribution of hematological diseases in Arica, Chile.

Prevalence and determinants of non-adherence to Imatinib in the first 3-months treatment among newly diagnosed Ethiopian's with chronic myeloid leukemia

Objectives

Imatinib has shown to be highly efficacious in the treatment of chronic myeloid leukemia (CML) but continuous dosing and patient adherence is essential treatment success. The study aimed to assess prevalence and reasons for non-adherence to Imatinib in newly diagnosed patients with CML in the first 3-months of treatment.

Methods

The study was conducted from October 1, 2016 to November 30, 2017 at Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia. A total of 147 newly diagnosed patients were followed and their adherence status was determined using the 8-items Morisky Medication Adherence Scale and reasons for their non-adherence were evaluated using semi-structured questionnaire. Descriptive statistics were used to summarize the data while multivariable logistic regression was employed to explore associations among variables of interest.

Results

Participants’ median age at time of confirmed diagnosis was 36 years; with most of them in the age group of <40 years (64.6%). Males comprised 59.2%. Adherence rate was found to be 55.1%. Those who lived in rural area, had low income, adverse drug events and comorbidity were significantly associated with treatment non-adherence. Most (68.4%) patients missed their medication due to adverse drug events. Three patients were lost-to-follow-up. Among 144 patients who finished the 3-month follow-up, 91.7% of them achieved complete hematologic remission. Morisky high adherent (AOR = 8.6, 95%CI:4.32–11.1) was positively associated with complete hematologic remission.

Conclusions

Overall treatment adherence is suboptimal. Thus, efforts should be made to improve adherence and further study is required to explore impact adherence on the cytogenetic and molecular responses of Ethiopian patients with CML.

Long noncoding RNA MEG3 inhibits proliferation of chronic myeloid leukemia cells by sponging microRNA21

The long noncoding RNA (lnc) maternally expressed 3 (MEG3) is downregulated in many types of cancers. However, the relationship between lncRNA MEG3, microRNA-21 (miR-21) and chronic myeloid leukemia (CML) blast crisis is unknown. This study examined bone marrow samples from 40 CML patients and 10 healthy donors. Proliferation and apoptosis assays, real-time polymerase chain reaction (PCR), bisulfite sequencing PCR, Western blotting, luciferase assay, RNA pull-down, RNA immunoprecipitation (RIP), co-immunoprecipitation (CoIP) and Chromatin immunoprecipitation (ChIP) were performed. We found that MEG3 and PTEN expression were down-regulated, whereas, MDM2, DNMT1 and miR-21 were up-regulated in the accelerated and blast phases of CML. Treated with 5-azacytidine decreased the level of MDM2, DNMT1 and miR21, but increased the level of MEG3 and PTEN. Overexpression of MEG3 and silencing the expression of miR-21 inhibited proliferation and induced apoptosis. MEG3 overexpression and silencing the expression of miR21 influence the levels of MMP-2, MMP-9, bcl-2 and Bax. MEG3 was able to interact with MDM2 and EZH2. MDM2 could interact with DNMT1 and PTEN. MYC and AKT can interact with EZH2. ChIP-seq showed that the promoter of KLF4 and SFRP2 interacts with DNMT1. In conclusion, lncRNA MEG3 and its target miR21 may serve as novel therapeutic targets for CML blast crisis; and demethylation drugs might also have potential clinical application in treating CML blast crisis.

Molecular and genetic alterations associated with therapy resistance and relapse of acute myeloid leukemia

Background

The majority of individuals with acute myeloid leukemia (AML) respond to initial chemotherapy and achieve a complete remission, yet only a minority experience long-term survival because a large proportion of patients eventually relapse with therapy-resistant disease. Relapse therefore represents a central problem in the treatment of AML. Despite this, and in contrast to the extensive knowledge about the molecular events underlying the process of leukemogenesis, information about the mechanisms leading to therapy resistance and relapse is still limited.

Purpose and content of review

Recently, a number of studies have aimed to fill this gap and provided valuable information about the clonal composition and evolution of leukemic cell populations during the course of disease, and about genetic, epigenetic, and gene expression changes associated with relapse. In this review, these studies are summarized and discussed, and the data reported in them are compiled in order to provide a resource for the identification of molecular aberrations recurrently acquired at, and thus potentially contributing to, disease recurrence and the associated therapy resistance. This survey indeed uncovered genetic aberrations with known associations with therapy resistance that were newly gained at relapse in a subset of patients. Furthermore, the expression of a number of protein coding and microRNA genes was reported to change between diagnosis and relapse in a statistically significant manner.

Conclusions

Together, these findings foster the expectation that future studies on larger and more homogeneous patient cohorts will uncover pathways that are robustly associated with relapse, thus representing potential targets for rationally designed therapies that may improve the treatment of patients with relapsed AML, or even facilitate the prevention of relapse in the first place.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-017-0416-0) contains supplementary material, which is available to authorized users.

What Is the Optimal Dose and Schedule for Dasatinib in Chronic Myeloid Leukemia: Two Case Reports and Review of the Literature

Efficacy and safety of dasatinib in chronic phase (CP) chronic myelogenous leukemia (CML) patients has been well established. Initially approved dose and schedule of 70 mg twice daily has been changed to 100 mg once daily after demonstration of the same efficacy with less toxicity. Some patients require significant dose reductions to enable continued treatment with dasatinib. Even at a dose of 80 mg once daily, several patients may require further dose reductions due to substantial toxicity while maintaining good control of their disease. We report two CP-CML patients achieving and maintaining major molecular responses while on very low doses of dasatinib, ultimately achieving undetectable levels of BCR-ABL fusion transcript in their peripheral blood. Observations of several CP-CML cases responding remarkably well to dasatinib despite very low dose and frequent dose interruptions challenge our current understanding and the accuracy of the data regarding the optimum dose and schedule of this drug. In selected intolerant patients, low-dose dasatinib therapy may be a safe and effective alternative treatment option before a treatment discontinuation or change considered.

Predicting Chronic Leukaemias from Assessment of Complete Peripheral Blood Counts

The chronic leukaemias include two distinct chronic neoplastic disease states, namely chronic myelogenous leukaemia (CML) and chronic lymphocytic leukaemia (CLL). The aim of this study was to assess the utility of leucocyte count, neutrophil percentage and absolute lymphocyte count from differential complete blood count analyses as indicators of the possible presence of CML and CLL. Blood counts from 102 patients with histopathologically confirmed CML and CLL were compared with counts for 858 cancer-free control subjects. Optimal cut-off values were identified by selecting values with the highest sensitivity–specificity combination for each blood count parameter for the two diseases. The results indicated that any individual with mature-appearing lymphocytes at a level > 6.65 × 109/l in the peripheral blood should be examined further for CLL, and that any individual with a leucocyte count > 18.0 × 109/l or a neutrophil proportion > 72.6% should be investigated for CML.

Knockdown of Peripheral Myelin Protein 22 Inhibits the Progression of Chronic Myeloid Leukemia

We aimed to explore the underlying mechanism of peripheral myelin protein 22 (PMP22) in the development of chronic myeloid leukemia (CML). The level of PMP22 expression in CD34⁺ cells isolated from CML patients’ bone marrow samples (BMMCs) and peripheral blood samples (PBMCs) was determined by RT-PCR. In addition, PMP22-siRNA and scrambled control siRNA were transfected into human CML cell line K562 with Lipofectamine 2000 reagent. Cell viability and apoptosis were, respectively, determined by MTT assay and flow cytometry. Besides, the level of caspase 3 and Bcl-xL was then detected using Western blot. The level of PMP22 expression in CML patients’ CD34⁺ cells isolated from both PBMCs and BMMCs was significantly higher than the control group. PMP22 expression in K562 cells was successfully knocked down by siRNA. MTT analysis showed that knockdown of PMP22 inhibited the proliferation of CML cells. Flow cytometry showed that knockdown of PMP22 promoted the apoptosis of CML cells. Besides, Bcl-xL expression markedly decreased, while the expression of caspase 3 in CML cells significantly increased after knockdown of PMP22 expression. Our findings indicate that high expression of PMP22 may promote cell proliferation and inhibit cell apoptosis via upregulation of Bcl-xL or inhibition of caspase 3 activation, and thus may contribute to the development of CML. PMP22 may serve as a novel therapeutic target for the treatment of CML.

Anticipating Clinical Resistance to Target-Directed Agents

The deregulated tyrosine kinase activity of BCR-ABL is necessary and sufficient to induce chronic myelogenous leukemia (CML). This observation has paved the way for the development of small-molecule inhibitors specifically targeting the kinase activity of the BCR-ABL protein. Indeed, the amazing success of imatinib has revolutionized the whole area of targeted cancer therapeutics. However, enthusiasm for the striking efficacy of imatinib has been tempered by the development of clinical resistance. In essentially all cases, resistance results from kinase domain mutations and/or overexpression of the BCR-ABL gene. To overcome resistance, several novel BCR-ABL inhibitors have been developed and are in clinical trials, though it is inevitable that resistance to second-generation inhibitors will occur as well. Nonetheless, kinases represent an attractive target for therapeutic intervention in several diseases and, at present, some 50 different kinase inhibitors are in clinical trials. We anticipate that resistance to these compounds will follow mechanisms similar to those observed with imatinib. Resistance mutations cause their effect either by direct steric hindrance to drug binding or by allosterically modulating kinase dynamics. This review highlights the principal mechanisms underlying point mutations from these two different classes to confer drug resistance.

IL-2R common gamma-chain is epigenetically silenced by nucleophosphin-anaplastic lymphoma kinase (NPM-ALK) and acts as a tumor suppressor by targeting NPM-ALK

Anaplastic lymphoma kinase (ALK), physiologically expressed only by certain neural cells, becomes highly oncogenic, when aberrantly expressed in nonneural tissues as a fusion protein with nucleophosphin (NPM) and other partners. The reason why NPM-ALK succeeds in transforming specifically CD4(+) T lymphocytes remains unknown. The IL-2R common γ-chain (IL-2Rγ) is shared by receptors for several cytokines that play key roles in the maturation and growth of normal CD4(+) T lymphocytes and other immune cells. We show that IL-2Rγ expression is inhibited in T-cell lymphoma cells expressing NPM-ALK kinase as a result of DNA methylation of the IL-2Rγ gene promoter. IL-2Rγ promoter methylation is induced in malignant T cells by NPM-ALK. NPM-ALK acts through STAT3, a transcription factor that binds to the IL-2Rγ gene promoter and enhances binding of DNA methyltransferases (DNMTs) to the promoter. In addition, STAT3 suppresses expression of miR-21, which selectively inhibits DNMT1 mRNA expression. Reconstitution of IL-2Rγ expression leads to loss of the NPM-ALK protein and, consequently, apoptotic cell death of the lymphoma cells. These results demonstrate that the oncogenic tyrosine kinase NPM-ALK induces epigenetic silencing of the IL-2Rγ gene and that IL-2Rγ acts as a tumor suppressor by reciprocally inhibiting expression of NPM-ALK.

A multicellular basis for the origination of blast crisis in chronic myeloid leukemia

Chronic myeloid leukemia (CML) is characterized by a specific chromosome translocation, and its pathobiology is considered comparatively well understood. Thus, quantitative analysis of CML and its progression to blast crisis may help elucidate general mechanisms of carcinogenesis and cancer progression. Hitherto, it has been widely postulated that CML blast crisis originates mainly via cell-autonomous mechanisms such as secondary mutations or genomic instability. However, recent results suggest that carcinogenic transformation may be an inherently multicellular event, in departure from the classic unicellular paradigm. We investigate this possibility in the case of blast crisis origination in CML. A quantitative, mechanistic cell population dynamics model was employed. This model used recent data on imatinib-treated CML; it also used earlier clinical data, not previously incorporated into current mathematical CML/imatinib models. With the pre-imatinib data, which include results on many more blast crises, we obtained evidence that the driving mechanism for blast crisis origination is a cooperation between specific cell types. Assuming leukemic-normal interactions resulted in a statistically significant improvement over assuming either cell-autonomous mechanisms or interactions between leukemic cells. This conclusion was robust with regard to changes in the model's adjustable parameters. Application of the results to patients treated with imatinib suggests that imatinib may act not only on malignant blast precursors, but also, to a limited degree, on the malignant blasts themselves.

"Real-life" results of front-line treatment with Imatinib in older patients (≥ 65 years) with newly diagnosed chronic myelogenous leukemia

The age role was evaluated in 117 consecutive patients with newly diagnosed CML at our Institution treated with front-line Imatinib from 9/02 to 3/08. Forty patients (34.1%) aged ≥ 65 years and 77 (65.9%) <65 years. Thirty-four older patients (85%) had at least 1 comorbidity versus 39 younger patients (50.6%) (p<0.001). Complete cytogenetic response (CCyR) was achieved in 34/40 older patients (85%) as compared to 69/77 younger patients (89.6%), without statistically significant differences. Severe (grades 3-4 WHO) hematological and extra-hematological toxicities were more common in older patients (p=0.02 and p=0.017, respectively). Rates of permanent Imatinib discontinuation and dose reduction to 300 mg or less were significantly higher in older patients (p=0.009 and p=0.001, respectively). In conclusion, Imatinib in older patients with newly diagnosed CML seems to have the same efficacy as in younger patients, but tends to be more toxic, leading to higher rates of discontinuation and dose reduction. To overcome this problem, future trials concerning best dosage in this subset of patients could be useful.

Therapeutic targeting of gene expression by siRNAs directed against BCR-ABL transcripts in a patient with imatinib-resistant chronic myeloid leukemia

Within the recent years, RNA interference (RNAi) has become an almost-standard method for in vitro knockdown of any target gene of interest. Now, one major focus is to further explore its potential in vivo, including the development of novel therapeutic strategies. From the mechanism, it becomes clear that small interfering RNAs (siRNAs) play a pivotal role in triggering RNAi. Thus, the efficient delivery of target gene-specific siRNAs is one major challenge in the establishment of therapeutic RNAi. Here we show that in vivo application of targeted nonvirally delivered synthetic bcr-abl siRNA in a female patient with recurrent Philadelphia chromosome positive chronic myeloid leukemia (CML) resistant to imatinib (Y253F mutation) and chemotherapy after allogeneic hematopoietic stem cell transplantation can silence the expression of bcr-abl gene. We found a remarkable inhibition of the overexpressed bcr-abl oncogene resulting in increased apoptosis of CML cells. In vivo siRNA application was well tolerated without any clinically adverse events. Our findings imply that the clinical application of synthetic siRNA is feasible, safe and has real potential for genetic-based therapies using synthetic nonviral carriers.

Prevalence, determinants, and outcomes of nonadherence to imatinib therapy in patients with chronic myeloid leukemia: the ADAGIO study

Imatinib mesylate (imatinib) has been shown to be highly efficacious in the treatment of chronic myeloid leukemia (CML). Continuous and adequate dosing is essential for optimal outcomes and with imatinib treatment possibly being lifelong, patient adherence is critical. The ADAGIO (Adherence Assessment with Glivec: Indicators and Outcomes) study aimed to assess prospectively over a 90-day period the prevalence of imatinib nonadherence in patients with CML; to develop a multivariate canonical correlation model of how various determinants may be associated with various measures of nonadherence; and to examine whether treatment response is associated with adherence levels. A total of 202 patients were recruited from 34 centers in Belgium, of whom 169 were evaluable. One-third of patients were considered to be nonadherent. Only 14.2% of patients were perfectly adherent with 100% of prescribed imatinib taken. On average, patients with suboptimal response had significantly higher mean percentages of imatinib not taken (23.2%, standard deviation [SD] = 23.8) than did those with optimal response (7.3%, SD = 19.3, P = .005; percentages calculated as proportions x 100). Nonadherence is more prevalent than patients, physicians, and family members believe it is, and therefore should be assessed routinely. It is associated with poorer response to imatinib. Several determinants may serve as alert signals, many of which are clinically modifiable.

Fluorescence in situ hybridization dissection of a chronic myeloid leukemia case bearing the apparently balanced translocations (9;22)(q34;q11.2) and (11;11)(p15;q13)

We report on a patient with chronic myeloid leukemia (CML), which was detected by conventional cytogenetic analysis, to carry two different acquired and apparently balanced translocations, (9;22)(q34;q11.2) and (11;11)(p15;q13). By fluorescence in situ hybridization characterization, we were able to finely map the genomic regions involved in the translocation breakpoints and to disclose concomitant deletions adjacent to the breakpoints on the two derivative chromosomes 11 and the derivative chromosome 22, and the insertion of a segment from chromosome band 11q12.2 into the derivative chromosome 9. We discuss the putative mechanism that could have led to the formation of this complex rearrangement and speculate on the role in leukemogenesis played by the genes mapping at the breakpoints and within the deleted regions.

Intermittent target inhibition with dasatinib 100 mg once daily preserves efficacy and improves tolerability in imatinib-resistant and -intolerant chronic-phase chronic myeloid leukemia

PURPOSE

Dasatinib is a BCR-ABL inhibitor, 325-fold more potent than imatinib against unmutated BCR-ABL in vitro. Phase II studies have demonstrated efficacy and safety with dasatinib 70 mg twice daily in chronic-phase (CP) chronic myelogenous leukemia (CML) after imatinib treatment failure. In phase I, responses occurred with once-daily administration despite only intermittent BCR-ABL inhibition. Once-daily treatment resulted in less toxicity, suggesting that toxicity results from continuous inhibition of unintended targets. Here, a dose- and schedule-optimization study is reported.

PATIENTS AND METHODS

In this open-label phase III trial, 670 patients with imatinib-resistant or -intolerant CP-CML were randomly assigned 1:1:1:1 between four dasatinib treatment groups: 100 mg once daily, 50 mg twice daily, 140 mg once daily, or 70 mg twice daily.

RESULTS

With minimum follow-up of 6 months (median treatment duration, 8 months; range, < 1 to 15 months), marked and comparable hematologic (complete, 86% to 92%) and cytogenetic (major, 54% to 59%; complete, 41% to 45%) response rates were observed across the four groups. Time to and duration of cytogenetic response were similar, as was progression-free survival (8% to 11% of patients experienced disease progression or died). Compared with the approved 70-mg twice-daily regimen, dasatinib 100 mg once daily resulted in significantly lower rates of pleural effusion (all grades, 7% v 16%; P = .024) and grade 3 to 4 thrombocytopenia (22% v 37%; P = .004), and fewer patients required dose interruption (51% v 68%), reduction (30% v 55%), or discontinuation (16% v 23%).

CONCLUSION

Dasatinib 100 mg once daily retains the efficacy of 70 mg twice daily with less toxicity. Intermittent target inhibition with tyrosine kinase inhibitors may preserve efficacy and reduce adverse events.

Overcoming kinase resistance in chronic myeloid leukemia

Imatinib is a small-molecule inhibitor of BCR-ABL tyrosine kinase activity, with proven efficacy and tolerability. Despite imatinib's activity, the development of resistance, whether BCR-ABL dependent or independent, is a concern. BCR-ABL-dependent resistance is commonly a result of mutations in the BCR-ABL gene, which can induce a structural predisposition towards the active conformation of the protein, resulting in a shift in the equilibrium of BCR-ABL from inactive, which imatinib binds, to active, which imatinib is unable to bind. BCR-ABL gene amplification may play a role in the development of imatinib resistance in patients with CML. There are a number of BCR-ABL-independent mechanisms of imatinib resistance, including the efflux protein multidrug resistance protein-1, of which imatinib is a substrate. Another mechanism may be the development of alternative pathways of disease progression, leading to less reliance on BCR-ABL; indeed, the SRC family tyrosine kinases LYN and HCK have been frequently implicated in treatment resistance and progression of CML. Clearly, imatinib resistance requires the development of other treatment options. Dasatinib, with increased binding potency (325-fold greater potency than imatinib for wild-type BCR-ABL), inhibition of both the active and inactive formation of BCR-ABL, and targeting of SRC family kinases, is the only agent approved for the treatment of patients with imatinib-resistant or -intolerant CML and Ph+ ALL. Dasatinib is highly active in all phases of these diseases, and is active in the majority of imatinib-resistant mutations, with the exception of T315I. The development of agents that effectively inhibit T315I mutations suggests that future treatment options will include combination therapy.

Quantitative expression analysis in peripheral blood of patients with chronic myeloid leukaemia: correlation between HMGA2 expression and white blood cell count

The architectural transcription factor HMGA2 is highly expressed during embryogenesis but scarcely detectable in non-dividing adult cells. Previously, HMGA2 re-expression was detected in blood from CML patients by conventional RT-PCR, while blood samples from healthy volunteers were HMGA2 negative. Using the sensitive method of real-time quantitative RT-PCR, herein HMGA2 expression was detectable not only in peripheral blood from leukaemia patients but also in blood from healthy donors. Statistical analysis revealed a highly significant correlation between white blood cell count and HMGA2 transcript levels. The results indicate that up-regulation of HMGA2 expression is correlated to the undifferentiated phenotype of leukaemic cells accumulating during progression of chronic phase to blast crisis.

FoxO tumor suppressors and BCR-ABL-induced leukemia: a matter of evasion of apoptosis

Numerous studies have revealed that the BCR-ABL oncoprotein abnormally engages a multitude of signaling pathways, some of which may be important for its leukemogenic properties. Central to this has been the determination that the tyrosine kinase function of BCR-ABL is mainly responsible for its transforming potential, and can be targeted with small molecule inhibitors, such as imatinib mesylate (Gleevec, STI-571). Despite this apparent success, the development of clinical resistance to imatinib therapy, and the inability of imatinib to eradicate BCR-ABL-positive malignant hematopoietic progenitors demand detailed investigations of additional effector pathways that can be targeted for CML treatment. The promotion of cellular survival via the suppression of apoptotic pathways is a fundamental characteristic of tumor cells that enables resistance to anti-cancer therapies. As substrates of survival kinases such as Akt, the FoxO family of transcription factors, particularly FoxO3a, has emerged as playing an important role in the cell cycle arrest and apoptosis of hematopoietic cells. This review will discuss our current understanding of BCR-ABL signaling with a focus on apoptotic suppressive mechanisms and alternative approaches to CML therapy, as well as the potential for FoxO transcription factors as novel therapeutic targets.

Imatinib mesylate therapy in chronic myeloid leukemia patients in stable complete cytogenic response after interferon-alpha results in a very high complete molecular response rate

To determine the impact on minimal residual disease by switching to imatinib chronic phase chronic myeloid leukaemia (CP-CML) patients responsive to interferon-alpha (IFNalpha), in stable complete cytogenetic response (CCR) but with persistent PCR positivity. Twenty-six Philadelphia positive (Ph+) CML patients in stable CCR after IFNalpha but persistently positive at PCR analysis during this treatment, were given imatinib mesylate at standard dose. At enrolment into the study, median IFN treatment and CCR duration were 88 months (range 15-202) and 73 months (range 10-148), respectively. Imatinib treatment resulted in a progressive and consistent decline of the residual disease as measured by quantitative PCR (RQ-PCR) in all but one of the 26 patients; at the end of follow-up, after a median of 32 months (range 21-49) of treatment, a major molecular response (BCR/ABL levels <0.1) was reached in 20 patients (77%), and BCR/ABL transcripts were undetectable in 13 (50%). The achievement of molecular response was significantly correlated with post-IFN baseline transcript level (mean 1.194 for patients achieving complete molecular response versus 18.97 for those who did not; p<0.001), but not with other clinical/biological disease characteristics. These results indicate that patients induced into CCR by IFN treatment represent a subset with very favourable prognosis, which can significantly improve molecular response with imatinib and further support investigative treatment schedules combining these two drugs.

Chronic myeloid leukaemia

Chronic myeloid leukaemia (CML) was the first neoplastic disease for which knowledge of the genotype led to a rationally designed therapy. As a result of its well known pathophysiology, straightforward diagnosis, well established prognostic factors, and treatment for the cause of disease, CML has been studied to an extent that far exceeds that expected from its frequency, and serves as a model disease for other cancers. Imatinib, an inhibitor of BCR-ABL tyrosine kinase, has revolutionised treatment of this disease, and is now recommended as standard treatment for chronic-phase CML. Interferon alfa is an acceptable alternative treatment in the early chronic phase for patients who do not tolerate imatinib. If imatinib treatment fails, allogeneic stem-cell transplantation, a dose increase of imatinib, or new drugs are recommended. Up to 87% of patients achieve complete cytogenetic remission, therefore we provide guidance for monitoring disease status. Many trials of new drugs and combination therapies that include imatinib are underway.

Therapeutic application of small interfering RNA directed against bcr-abl transcripts to a patient with imatinib-resistant chronic myeloid leukaemia

RNA interference is referred to as the recently discovered process of sequence-specific, post-transcriptional gene silencing that is initiated by double-stranded RNA molecules known as small interfering RNAs (siRNA). We herein present a first report on the in vivo application of targeted non-virally delivered synthetic bcr-abl siRNA in a female patient with recurrent Philadelphia chromosome-positive chronic myeloid leukaemia (CML) resistant to imatinib (Y253F mutation) and chemotherapy after allogeneic haematopoietic stem cell transplantation. We found a remarkable inhibition of the overexpressed bcr-abl oncogene resulting in increased apoptosis of CML cells. In vivo siRNA application was well tolerated without any clinically adverse events. Our findings imply that the clinical application of synthetic siRNA is feasible, safe and has real potential for genetic-based therapies using synthetic non-viral carriers.

Drug treatment is superior to allografting as first-line therapy in chronic myeloid leukemia

Early allogeneic hematopoietic stem cell transplantation (HSCT) has been proposed as primary treatment modality for patients with chronic myeloid leukemia (CML). This concept has been challenged by transplantation mortality and improved drug therapy. In a randomized study, primary HSCT and best available drug treatment (IFN based) were compared in newly diagnosed chronic phase CML patients. Assignment to treatment strategy was by genetic randomization according to availability of a matched related donor. Evaluation followed the intention-to-treat principle. Six hundred and twenty one patients with chronic phase CML were stratified for eligibility for HSCT. Three hundred and fifty four patients (62% male; median age, 40 years; range, 11-59 years) were eligible and randomized. One hundred and thirty five patients (38%) had a matched related donor, of whom 123 (91%) received a transplant within a median of 10 months (range, 2-106 months) from diagnosis. Two hundred and nineteen patients (62%) had no related donor and received best available drug treatment. With an observation time up to 11.2 years (median, 8.9 years), survival was superior for patients with drug treatment (P = .049), superiority being most pronounced in low-risk patients (P = .032). The general recommendation of HSCT as first-line treatment option in chronic phase CML can no longer be maintained. It should be replaced by a trial with modern drug treatment first.

Forthcoming receptor tyrosine kinase inhibitors

Receptor tyrosine kinases play a significant role in carcinogenesis and have been successfully targeted with monoclonal antibodies and small-molecule inhibitors. There have been recent developments in the understanding of receptor tyrosine kinase signal transduction which have enabled better drug development. The use of receptor tyrosine kinase inhibitors in clinical practice has expanded the knowledge on cancer biology, in particular the understanding of resistant mutations and strategies to overcome such resistance. This has driven drug development from single kinase inhibitors to multi-kinase inhibitors and high-affinity kinase inhibitors. Finally, as the use of receptor tyrosine kinase inhibitors grows in clinical practice, more is learned about appropriate patient selection for such therapies. This is an exciting time in cancer therapeutics, highlighted by the advent of effective targeted therapy with receptor tyrosine kinase inhibitors.

New insights into the pathobiology and treatment of chronic myelogenous leukemia

Chronic myelogenous leukemia (CML) is one of the most frequently diagnosed forms of leukemia. Recent advances in the understanding of the molecular mechanisms involved in the pathogenesis of this disorder led to new diagnostic and therapeutic approaches. From a disease that used to be diagnosed purely on morphologic grounds, CML is now an entity that cannot be diagnosed in the absence of relevant cytogenetic or molecular data. Identification of the characteristic t(9;22) cytogenetic abnormality or of the BCR-ABL molecular abnormality is mandatory, as current treatment approaches rely on the use of agents active against this specific molecular target. This article presents the evolution in the understanding of the pathogenic mechanisms involved in CML, as well as the methods and the criteria currently in use in its diagnosis and treatment.

Molekular zielgerichtete Therapie

Until recently, cancer therapy was based on three modalities: surgery, radiotherapy, and cytostatic chemotherapy. In most instances treatment of solid tumors was a surgical domain. For patients with incomplete resection or relapse after surgery, radiotherapy and chemotherapy usually offered only partial response and mostly of limited duration. By the mid-1990s visions of antibody-based therapies, vaccination strategies, and even gene-specific therapies existed but seemed far from clinical practice. United States Federal Drug Administration approval of the humanized antibody rituximab (1997) and the tyrosine kinase inhibitor imatinib (2001) has changed perceptions of oncologic treatment. These drugs turned visions into reality and led the pharmaceutical industry, clinicians, and patients to new perspectives. This article gives an overview of the development of this fourth modality in cancer therapy, so-called targeted therapy.

Treatment of chronic myeloid leukemia with imatinib mesylate

Philadelphia (Ph) chromosome is the cytogenetic hallmark of chronic myeloid leukemia (CML). The translocation forms a chimeric gene, bcr-abl, which generates BCR-ABL. This fusion protein constitutively activate ABL tyrosine kinase and causes CML. Imatinib mesylate is a selective tyrosine kinase inhibitor on ABL, c-Kit and PGDF-receptor, and functions through competitive inhibition at the ATP-binding site of the enzyme, which leads to growth arrest or apoptosis in cells that express BCR-ABL. Imatinib has revolutionized the management of patients with CML, and at a dose of 400 mg daily has become the current standard therapy for newly diagnosed patients with CML even when they have HLA-matched family donors. Although imatinib therapy has only a 5-year history, it is hoped that CML will be cured with this drug and with forthcoming second-generation tyrosine kinase inhibitors as well as by allogeneic stem cell transplantation in patients who have become resistant to these drugs.

Gene expression profiling of CD34+ cells identifies a molecular signature of chronic myeloid leukemia blast crisis

Despite recent success in the treatment of early-stage disease, blastic phase (BP) of chronic myeloid leukemia (CML) that is characterized by rapid expansion of therapy-refractory and differentiation-arrested blasts, remains a therapeutic challenge. The development of resistance upon continuous administration of imatinib mesylate is associated with poor prognosis pointing to the need for alternative therapeutic strategies and a better understanding of the molecular mechanisms underlying disease progression. To identify transcriptional signatures that may explain pathological characteristics and aggressive behavior of BP blasts, we performed comparative gene expression profiling on CD34+ Ph+ cells purified from patients with untreated newly diagnosed chronic phase CML (CP, n=11) and from patients in BP (n=9) using Affymetrix oligonucleotide arrays. Supervised microarray data analysis revealed 114 differentially expressed genes (P<10(-4)), 34 genes displaying more than two-fold transcriptional changes when comparing CP and BP groups. While 24 of these genes were downregulated, 10 genes, especially suppressor of cytokine signalling 2 (SOCS2), CAMPATH-1 antigen (CD52), and four human leukocyte antigen-related genes were strongly overexpressed in BP. Expression of selected genes was validated by real-time-polymerase chain reaction and flow cytometry. Our data suggest the existence of a common gene expression profile of CML-BP and provide new insight into the molecular phenotype of blasts associated with disease progression and high malignancy.

[Hematological side effects of tyrosine kinase inhibition using imatinib]

Imatinib (STI571, Gleevec/Glivec) and other small-molecule tyrosine kinase inhibitors are highly effective in the treatment of chronic myeloid leukemia (CML), gastrointestinal stromal tumors and, for example, eosinophilia-associated chronic myeloproliferative disorders. This molecularly targeted approach disrupts abnormal tyrosine kinase dependent signalling pathways, thus providing a preferred treatment option for selected neoplastic disorders with activating mutations of Abelson-, Abl-related-, Kit-, and platelet-derived growth factor receptor A and B genes. Loss of response to imatinib may be due to an acquired resistance of emerging mutant tumor cell clones. Therapy is generally well tolerated. However, toxicities including edema, skin rashes, fatigue, nausea and myelosuppression have been reported. Philadelphia/Bcr-Abl-negative clonal chromosomal abnormalities may develop. Bone marrow trephines obtained from CML patients in complete remission with prolonged pancytopenia secondary to imatinib generally show marrow hypoplasia. Morphological features may be in keeping with either aplastic anemia or myelodysplasia developing in Philadelphia-negative hematopoiesis. Single or multilineage myelodysplasia may be accompanied by an excess of blasts and rarely evolves into acute leukemia in CML patients. Severe adverse hematological effects of imatinib are extremely rare. Current questions involve the molecular mechanisms of hematological side effects of tyrosine kinase inhibitors with special regard to the emergence of distinct aberrant clones.

Molecularly targeted therapies in myelodysplastic syndromes and acute myeloid leukemias

Although there has been significant progress in acute myeloid leukemia (AML) treatment in younger adults during the last decade, standard induction therapy still fails to induce remission in up to 40% of AML patients. Additionally, relapses are common in 50-70% of patients who achieve a complete remission, and only 20-30% of patients enjoy long-term disease-free survival. The natural history of myelodysplastic syndrome (MDS) is variable, with about half of the patients dying from cytopenic complications, and an additional 20-30% transforming to AML. The advanced age of the majority of MDS patients limits the therapeutic strategies often to supportive care. To address these shortcomings, much effort has been directed toward the development of novel treatment strategies that target the evolution and proliferation of malignant clones. Presented here is an overview of molecularly targeted therapies currently being tested in AML and MDS patients, with a focus on FMS-like tyrosine kinase 3 inhibitors, farnesyltransferase inhibitors, antiangiogenesis agents, DNA hypomethylation agents, and histone deacetylase inhibitors.

Centrosome aberrations in chronic myeloid leukemia correlate with stage of disease and chromosomal instability

Centrosome abnormalities are hallmarks of various cancers and have been implicated in chromosome missegregation, chromosomal instability, and aneuploidy. Since genetic instability is a common feature in chronic myeloid leukemia (CML), we sought to investigate whether centrosome aberrations occur and correlate with disease stage and cytogenetic findings in CML. We examined 34 CML samples including CD 34+Ph+cells of 18 newly diagnosed patients (chronic phase (CP)) and 16 blast crisis (BC) specimens by using a centrosome-specific antibody to pericentrin. All CP and BC samples displayed centrosome alterations as compared with corresponding CD 34+control cells. Centrosome abnormalities were detected in 29.1+/-5.9% of CP blasts and in 54.3+/-4.8% of BC blasts, but in only 2.4+/-1.1% of controls (P<0.0001). Additional karyotypic alterations to the t(9;22) translocation were found in only 1/18 CML-CP patients. In contrast, 11/16 (73%) CML-BC patients displayed additional karyotype alterations in 48.7% of analyzed cells, correlating with an abnormal centrosome status (P=0.0005). Our results indicate that centrosome defects are a common and early detectable feature in CML that may contribute to acquisition of chromosomal aberrations and aneuploidy. They may be considered as the driving force of disease progression and could serve as future prognostic markers.