Chronic myeloid leukemia: 2012 update on diagnosis, monitoring, and management

What can rheumatologists learn from translational cancer therapy?

It is well established that an intimate connection exists between inflammation and neoplasia. Indeed, particular chronic infections and autoimmune processes giving rise to prolonged site-specific inflammation are known to increase the probability of the development of specific cancers. Molecular characterisation of these processes has revealed profound similarities in the specific molecules involved in persistence of inflammation and in both the primary induction of neoplastic processes and in specification of the preferred anatomic sites of metastatic spread. The therapeutic importance of these findings is underscored by the remarkable success in the treatment of autoimmune pathology using medications initially developed for use in oncology and this arena is one of considerable therapeutic promise for rheumatologists.

miR‑107 promotes the erythroid differentiation of leukemia cells via the downregulation of Cacna2d1

microRNAs (miRNAs) have been reported to be involved in various human diseases. They may have uses in diagnosis and as therapeutic targets, thus the discovery of novel miRNAs has the potential to provide clinical tools or shed light on novel mechanisms. In the current study, miR‑107 was revealed to be downregulated in chronic myeloid leukemia cells. Overexpression of miR‑107 in K562 and KCL‑22 chronic myeloid leukemia cells promotes erythroid differentiation, while having no effect on cell proliferation. Further bioinformatics predicted that one target of miR‑107 may be Cacna2d1, a calcium channel protein. A luciferase reporter assay and quantitative polymerase chain reaction were utilized to confirm that Cacna2d1 is a target molecule of miR-107. The effect of miR‑107 on K562 and KCL‑22 cells was mediated through the downregulation of Cacna2d1, as rescued expression of Cacna2d1 reversed the effects of miR‑107. In summary, the current study identified a novel miRNA that is involved in chronic myeloid leukemia cell erythroid differentiation and the associated mechanisms, making it a potential therapeutic target in the treatment of chronic myeloid leukemia.

Practice gaps and barriers to optimal care of hematologic malignancies in the United States

BACKGROUND

Treating patients with hematologic malignancies can be challenging for physicians because of the rapidly evolving standards of care and relatively low incidence of these diseases.

OBJECTIVE

To identify clinical challenges among hematologists and medical oncologists regarding the provision of care to patients with chronic myeloid leukemia (CML), acute lymphoblastic leukemia (ALL), or B-cell lymphomas. Methods Hematologists and medical oncologists in active practice in the United States and who have a case load of ≥ 1 patient a year with CML, ALL, or B-cell lymphoma were recruited. The initial qualitative phase consisted of an online case-based survey followed by an interview exploring the contextual and behavioral factors that influence treatment decisions (n = 27). The analysis of qualitative data then informed a quantitative phase, in which 121 participants completed an online survey composed of case vignettes, multiple choice, and semantic differential rating scale questions. The respondents' answers were compared with recommendations from treatment guidelines and faculty experts.

RESULTS

A higher frequency of bone marrow biopsies was reported compared with expert faculty recommendations by 74% of oncologists. Many respondents failed to recognize the clinical relevance of BCR-ABL mutations other than T315I. Respondents reported perceiving difficulties in individualizing treatment and interpreting response to treatment in patients with ALL and B-cell lymphomas. Fewer than 30% of respondents recognized the mechanisms of action of 5 of the 9 promising investigational agents presented.

LIMITATIONS

Participant self-selection bias is a possibility because participation was voluntary. Practice gaps are not based on clinical data, but hypothetical case situations and self-report.

CONCLUSIONS

Findings from this study can guide education to address the identified challenges in caring for patients with hematologic malignancies and improving patient care.

FUNDING

This needs assessment was financially supported with an educational research grant from Pfizer Medical Education Group to the Annenberg Center for Health Sciences at Eisenhower.

Polymorphism of XRCC1, XRCC3, and XPD genes and risk of chronic myeloid leukemia

The genetic polymorphisms of X-ray repair cross complementing group 1 (XRCC1), X-ray repair cross complementing group 3 (XRCC3), and xeroderma pigmentosum complementation group D (XPD) repair genes may lead to genetic instability and leukemogenesis. The purpose of the study was to evaluate the association between XRCC1 Arg399Gln, Arg280His and Arg194Trp, XRCC3 Thr241Met, and XPD Lys751Gln polymorphisms and the risk of developing CML in Romanian patients. A total of 156 patients diagnosed with CML and 180 healthy controls were included in this study. We found no association between CML and XRCC1 or XRCC3 variant genotypes in any of the investigated cases. A significant difference was observed in the variant genotype frequencies of the XPD Lys751Gln polymorphism between the patients with CML and control group (for variant homozygous genotypes, OR = 2.37; 95% CI = 1.20–4.67; P value = 0.016 and for combined heterozygous and variant homozygous genotypes, OR = 1.72; 95% CI = 1.10–2.69; P value = 0.019). This was also observed when analyzing the variant 751Gln allele (OR = 1.54; 95% CI = 1.13–2.11; P value = 0.008). Our results suggest that the XPD Lys751Gln variant genotype increases the risk of CML.

Insight into the allosteric inhibition of Abl kinase

Abl kinase inhibitors targeting the ATP binding pocket are currently used as a front-line therapy for the treatment of chronic myelogenous leukemia (CML), but their use has significant limitation because of the development of drug resistance (especially due to the T315I mutation). Two compounds (GNF-2 and BO1) have been found able to inhibit the Abl activity through a peculiar mechanism of action. Particularly, GNF-2 acts as allosteric inhibitor against Bcr-Abl wild type (wt), but it has no activity against the gatekeeper mutant T315I. Its activity against the last mutant reappears when used together with an ATP-competitive inhibitor such as Imatinib or Nilotinib. A crystal structure of GNF-2 bound to the Abl myristoyl pocket (MP) has been released. On the contrary, BO1 shows an ATP-competitive/mixed mechanism of action against the wt, while it acts as an allosteric inhibitor against T315I. In order to better understand the mechanism of Abl allosteric inhibition, MD simulations and MM/GBSA analysis were performed on Abl wt and T315I in complex with GNF-2 and BO1, and the results were compared to those found for the natural myristoyl ligand. Similarly to that observed for the myristoyl group, the binding of an allosteric inhibitor to the MP promotes the formation of a compact and inhibited conformation of the wt protein, characterized by the stabilization of the intramolecular interactions that occur between SH2-SH3 and kinase domains. Conversely, an overall higher flexibility was observed with the Abl T315I mutant, especially in the case of GNF-2. Our analysis highlighted differences in the dynamic behavior of GNF-2 and BO1 which could explain the different biological profiles of the two allosteric inhibitors against the T315I mutant.

The prognostic impact of minimal residual disease in patients with chronic lymphocytic leukemia requiring first-line therapy

A proportion of patients with chronic lymphocytic leukemia achieve a minimal residual disease negative status after therapy. We retrospectively evaluated the impact of minimal residual disease on the outcome of 255 consecutive patients receiving any front-line therapy in the context of a detailed prognostic evaluation, including assessment of IGHV, TP53, NOTCH1 and SF3B1 mutations. The median follow-up was 73 months (range, 2-202) from disease evaluation. The median treatment-free survival durations for patients achieving a complete response without or with minimal residual disease, a partial response and no response were 76, 40, 11 and 11 months, respectively (P<0.001). Multivariate analysis revealed that three variables had a significant impact on treatment-free survival: minimal residual disease (P<0.001), IGHV status (P<0.001) and β2-microglobulin levels (P=0.012). With regards to overall survival, factors predictive of an unfavorable outcome were minimal residual disease positivity (P=0.014), together with advanced age (P<0.001), unmutated IGHV status (P=0.001), TP53 mutations (P<0.001) and elevated levels of β2-microglobulin (P=0.003). In conclusion, for patients requiring front-line therapy, achievement of minimal residual disease negativity is associated with significantly prolonged treatment-free and overall survival irrespective of other prognostic markers or treatment administered.

Pharmacogenomics and adverse drug reactions in children

Adverse drug reactions are a common and important complication of drug therapy in children. Over the past decade it has become increasingly apparent that genetically controlled variations in drug disposition and response are important determinants of adverse events for many important adverse events associated with drug therapy in children. While this research has been difficult to conduct over the past decade technical and ethical evolution has greatly facilitated the ability of investigators to conduct pharmacogenomic studies in children. Some of this research has already resulted in changes in public policy and clinical practice, for example in the case of codeine use by mothers and children. It is likely that the use of pharmacogenomics to enhance drug safety will first be realized among selected groups of children with high rates of drug use such as children with cancer, but it also likely that this research will be extended to other groups of children who have high rates of drug utilization and as well as providing insights into the mechanisms and pathophysiology of adverse drug reactions in children.

Eradication of bone marrow minimal residual disease may prompt early treatment discontinuation in CLL

The high complete remission rate with first-line combined fludarabine, cyclophosphamide, and rituximab (FCR) begs the question of the value of minimal residual disease (MRD)-negative status as a treatment end point. We report on 237 patients with chronic lymphocytic leukemia who received first-line FCR. MRD was prospectively assessed by 4-color flow cytometry in bone marrow after course 3 and at final response assessment. After course 3 and at final response assessment, 17% and 43% of patients were MRD negative in bone marrow, respectively. A mutated immunoglobulin heavy chain variable gene and trisomy 12 were independently associated with MRD-negative status both after 3 courses of FCR and at final response assessment in multivariable analyses (MVAs). MRD-negative status was independently associated with significantly longer progression-free survival (PFS) and overall survival (OS) in MVA (P = .03 and .02, respectively). This association was confirmed also on landmark MVA at the time of MRD assessment (P = .04 and .05, respectively). MRD-negative patients had comparable PFS and OS, independent of the number of courses received or interim staging. Early MRD eradication may be a desirable goal, prompting consideration of early discontinuation of treatment. This trial was registered at www.clinicaltrials.gov as #NCT00759798.

MTSS1 is a metastasis driver in a subset of human melanomas

In cancers with a highly altered genome, distinct genetic alterations drive subsets rather than the majority of individual tumours. Here we use a sequential search across human tumour samples for transcript outlier data points with associated gene copy number variations that correlate with patient's survival to identify genes with pro-invasive functionality. Employing loss and gain of function approaches in vitro and in vivo, we show that one such gene, MTSS1, promotes the ability of melanocytic cells to metastasize and engages actin dynamics via Rho-GTPases and cofilin in this process. Indeed, high MTSS1 expression defines a subgroup of primary melanomas with unfavourable prognosis. These data underscore the biological, clinical and potential therapeutic implications of molecular subsets within genetically complex cancers.

Decreased frequency, but normal functional integrity of mesenchymal stromal cells derived from untreated and Imatinib-treated chronic myeloid leukemia patients

In vitro, Imatinib inhibits the proliferation and stimulates the osteogenic and adipogenic differentiation of mesenchymal stromal cells (MSC). However, it is unknown whether Imatinib affects the biology of MSC in vivo. We asked whether MSC from long-term Imatinib-treated CML patients were affected by the in vivo treatment. MSC from untreated and Imatinib-treated patients displayed normal functional properties (i.e. proliferation, immunophenotype, differentiation and hematopoietic supportive capacity) - but a decreased frequency. In vitro, Imatinib lost its effect when discontinued; which suggest that it has a reversible effect on MSC. Therefore it might lose its effect on MSC after discontinuation in vivo.

BCR-ABL residues interacting with ponatinib are critical to preserve the tumorigenic potential of the oncoprotein

Patients with chronic myeloid leukemia in whom tyrosine kinase inhibitors (TKIs) fail often present mutations in the BCR-ABL catalytic domain. We noticed a lack of substitutions involving 4 amino acids (E286, M318, I360, and D381) that form hydrogen bonds with ponatinib. We therefore introduced mutations in each of these residues, either preserving or altering their physicochemical properties. We found that E286, M318, I360, and D381 are dispensable for ABL and BCR-ABL protein stability but are critical for preserving catalytic activity. Indeed, only a "conservative" I360T substitution retained kinase proficiency and transforming potential. Molecular dynamics simulations of BCR-ABL(I360T) revealed differences in both helix αC dynamics and protein-correlated motions, consistent with a modified ATP-binding pocket. Nevertheless, this mutant remained sensitive to ponatinib, imatinib, and dasatinib. These results suggest that changes in the 4 BCR-ABL residues described here would be selected against by a lack of kinase activity or by maintained responsiveness to TKIs. Notably, amino acids equivalent to those identified in BCR-ABL are conserved in 51% of human tyrosine kinases. Hence, these residues may represent an appealing target for the design of pharmacological compounds that would inhibit additional oncogenic tyrosine kinases while avoiding the emergence of resistance due to point mutations.

Expression of the essential Kinase PfCDPK1 from Plasmodium falciparum in Toxoplasma gondii facilitates the discovery of novel antimalarial drugs

We have previously shown that genetic disruption of Toxoplasma gondii calcium-dependent protein kinase 3 (TgCDPK3) affects calcium ionophore-induced egress. We examined whether Plasmodium falciparum CDPK1 (PfCDPK1), the closest homolog of TgCDPK3 in the malaria parasite P. falciparum, could complement a TgCDPK3 mutant strain. PfCDPK1 is essential and plays critical roles in merozoite development, motility, and secretion. We show that expression of PfCDPK1 in the TgCDPK3 mutant strain rescues the egress defect. This phenotypic complementation requires the localization of PfCDPK1 to the plasma membrane and kinase activity. Interestingly, PfCDPK1-expressing Toxoplasma becomes more sensitive to egress inhibition by purfalcamine, a potent inhibitor of PfCDPK1 with low activity against TgCDPK3. Based on this result, we tested eight small molecules previously determined to inhibit the kinase activity of recombinant PfCDPK1 for their abilities to inhibit ionophore-induced egress in the PfCDPK1-expressing strain. While two of these chemicals did not inhibit egress, we found that six drugs affected this process selectively in PfCDPK1-expressing Toxoplasma. Using mutant versions of PfCDPK1 and TgCDPK3, we show that the selectivities of dasatinib and PLX-4720 are regulated by the gatekeeper residue in the ATP binding site. Importantly, we have confirmed that the three most potent inhibitors of egress in the PfCDPK1-expressing strain effectively kill P. falciparum. Thus, we have established and validated a recombinant strain of Toxoplasma that can be used as a surrogate for the discovery and analysis of PfCDPK1-specific inhibitors that can be developed as antimalarials.

Aiming for the outliers: cancer precision medicine through targeting kinases with extreme expression

With the increasing availability of highly potent, pharmacologically active, and selective protein kinase inhibitors, identification of individuals who would benefit from targeted kinase inhibitors could facilitate application of precision medicine strategies for cancer therapy. A recent study by Kothari and colleagues reports preclinical studies that highlight the potential of targeting kinases with extreme expression for cancer precision medicine, warranting further clinical investigation of an individual-specific outlier kinase targeting approach.

Determinants of survival in patients with chronic myeloid leukaemia treated in the new era of oral therapy: findings from a UK population-based patient cohort

OBJECTIVES

To examine contemporary survival patterns in the general population of patients diagnosed with chronic myeloid leukaemia (CML), and to identify patient groups with less than optimal outcomes.

DESIGN

Prospective population-based cohort.

SETTING

The UK's Haematological Malignancy Research Network (catchment population 3.6 million, with >2000 new haematological malignancies diagnosed annually).

PARTICIPANTS

All patients newly diagnosed with CML, from September 2004 to August 2011 and followed up to 31 March 2013.

MAIN OUTCOME MEASURE

Incidence and survival.

RESULTS

With a median diagnostic age of 59 years, the CML age standardised (European) incidence was 0.9/100 000 (95% CIs 0.8 to 0.9), 5-year overall survival was 78.9% (72.3 to 84.0) and 5-year relative survival 88.6% (81.0 to 93.3). The efficacy of treatment across all ages was clearly demonstrated; the relative survival curves for those under 60 and over 60 years being closely aligned. Survival findings were similar for men and women, but varied with deprivation; the age and sex adjusted HR being 3.43 (1.89 to 6.22) for deprivation categories 4-5 (less affluent) versus 1-3 (more affluent). None of these differences were attributable to the biological features of the disease.

CONCLUSIONS

When therapy is freely provided, population-based survival for CML is similar to that reported in clinical trials, and age loses its prognostic significance. However, although most of the patients with CML now experience close to normal lifespans, those living in more deprived areas tend to have poorer outcomes, despite receiving the same clinical care. A significant improvement in overall population outcomes could be achieved if these socioeconomic differences, which may reflect the treatment compliance, could be eliminated.

The tyrosine kinase inhibitor Dasatinib blocks in-vitro HIV-1 production by primary CD4+ T cells from HIV-1 infected patients

HIV reservoirs persistence despite antiretroviral therapy (ART) might be related to persistent immune activation and residual HIV production, requiring further therapeutic strategies. We demonstrated that the tyrosine kinase inhibitor (TKI) Dasatinib, used for chronic myeloid leukaemia, significantly blocks in vitro HIV1 production by 3.4 logs in HIV1-infected primary CD4 T lymphocytes, by inhibiting cell activation and proliferation, without cell toxicity. This molecule deserves to be investigated further for HIV cure strategies to hinder persistent immune activation and residual viral production.

Pharmacological and genomic profiling identifies NF-κB-targeted treatment strategies for mantle cell lymphoma

Mantle cell lymphoma (MCL) is an aggressive malignancy that is characterized by poor prognosis. Large-scale pharmacological profiling across more than 100 hematological cell line models identified a subset of MCL cell lines that are highly sensitive to the B cell receptor (BCR) signaling inhibitors ibrutinib and sotrastaurin. Sensitive MCL models exhibited chronic activation of the BCR-driven classical nuclear factor-κB (NF-κB) pathway, whereas insensitive cell lines displayed activation of the alternative NF-κB pathway. Transcriptome sequencing revealed genetic lesions in alternative NF-κB pathway signaling components in ibrutinib-insensitive cell lines, and sequencing of 165 samples from patients with MCL identified recurrent mutations in TRAF2 or BIRC3 in 15% of these individuals. Although they are associated with insensitivity to ibrutinib, lesions in the alternative NF-κB pathway conferred dependence on the protein kinase NIK (also called mitogen-activated protein 3 kinase 14 or MAP3K14) both in vitro and in vivo. Thus, NIK is a new therapeutic target for MCL treatment, particularly for lymphomas that are refractory to BCR pathway inhibitors. Our findings reveal a pattern of mutually exclusive activation of the BCR-NF-κB or NIK-NF-κB pathways in MCL and provide critical insights into patient stratification strategies for NF-κB pathway-targeted agents.

Pharmacogenomics in children

Historically genetics has not been considered when prescribing drugs for children. However, it is clear that genetics are not only an important determinant of disease in children but also of drug response for many important drugs that are core agents used in the therapy of common problems in children. Advances in therapy and in the ethical construct of children's research have made pharmacogenomic assessment for children much easier to pursue. It is likely that pharmacogenomics will become part of the therapeutic decision making process for children, notably in areas such as childhood cancer where the benefits and risks of therapy are considerable.

Heparin-binding epidermal growth factor-like growth factor/diphtheria toxin receptor in normal and neoplastic hematopoiesis

Heparin-binding EGF-like growth factor (HB-EGF) belongs to the EGF family of growth factors. It is biologically active either as a molecule anchored to the membrane or as a soluble form released by proteolytic cleavage of the extracellular domain. HB-EGF is involved in relevant physiological and pathological processes spanning from proliferation and apoptosis to morphogenesis. We outline here the main activities of HB-EGF in connection with normal or neoplastic differentiative or proliferative events taking place primitively in the hematopoietic microenvironment.

Rapid identification of compound mutations in patients with Philadelphia-positive leukaemias by long-range next generation sequencing

An emerging problem in patients with Philadelphia (Ph)-positive leukaemias is the occurrence of cells with multiple mutations in the BCR-ABL1 tyrosine kinase domain (TKD) associated with high resistance to different tyrosine kinase inhibitors. Rapid and sensitive detection of leukaemic subclones carrying such changes, referred to as compound mutations, is therefore of increasing clinical relevance. However, current diagnostic methods including next generation sequencing (NGS) of short fragments do not optimally meet these requirements. We have therefore established a long-range (LR) NGS approach permitting massively parallel sequencing of the entire TKD length of 933bp in a single read using 454 sequencing with the GS FLX+ instrument (454 Life Sciences). By testing a series of individual and consecutive specimens derived from six patients with chronic myeloid leukaemia, we demonstrate that long-range NGS analysis permits sensitive identification of mutations and their assignment to the same or to separate subclones. This approach also facilitates readily interpretable documentation of insertions and deletions in the entire BCR-ABL1 TKD. The long-range NGS findings were reevaluated by an independent technical approach in select cases. Polymerase chain reaction (PCR) amplicons of the BCR-ABL1 TKD derived from individual specimens were subcloned into pGEM®-T plasmids, and >100 individual clones were subjected to analysis by Sanger sequencing. The NGS results were confirmed, thus documenting the reliability of the new technology. Long-range NGS analysis therefore provides an economic approach to the identification of compound mutations and other genetic alterations in the entire BCR-ABL1 TKD, and represents an important advancement of the diagnostic armamentarium for rapid assessment of impending resistant disease.

U.S. Food and Drug Administration approval summary: omacetaxine mepesuccinate as treatment for chronic myeloid leukemia

On October 26, 2012, the U.S. Food and Drug Administration (FDA) granted accelerated approval to omacetaxine mepesuccinate (Synribo; Teva Pharmaceuticals USA, Inc., North Wales, PA, http://www.tevausa.com) for the treatment of adult patients with chronic phase (CP) or accelerated phase (AP) chronic myeloid leukemia (CML) with resistance and/or intolerance to two or more tyrosine kinase inhibitors (TKIs). The approval was based on the FDA review of data from 111 patients with CML in CP or in AP who had received two or more prior TKIs, including imatinib. Major cytogenetic response was achieved in 18% of patients with CP, with a median response duration of 12.5 months. Major hematologic response was achieved in 14% of patients with AP, with a median response duration of 4.7 months. The FDA safety evaluation was based on submitted data from 163 patients with CP or AP CML who had received at least one dose of omacetaxine mepesuccinate. The safety evaluation was limited by the single-arm design of the clinical trials as conducted in a small number of previously treated patients. The most common (≥20%) adverse reactions of any grade in enrolled patients included thrombocytopenia, anemia, neutropenia, diarrhea, nausea, fatigue, asthenia, injection site reaction, pyrexia, and infection. The FDA concluded that omacetaxine mepesuccinate has shown activity and a favorable benefit-to-risk profile for the studied population of adult patients with CML (CP or AP) with resistance and/or intolerance to two or more TKIs. Further evidence of response durability to verify clinical benefit is pending.

Unconventional plasticity of HIV-1 reverse transcriptase: how inhibitors could open a connection "gate" between allosteric and catalytic sites

Targeted molecular dynamics (TMD) simulations allowed for identifying the chemical/structural features of the nucleotide-competitive HIV-1 inhibitor DAVP-1, which is responsible for the disruption of the T-shape motif between Try183 and Trp229 of the reverse transcriptase (RT). DAVP-1 promoted the opening of a connection "gate" between allosteric and catalytic sites of HIV-1 RT, thus explaining its peculiar mechanism of action and providing useful insights to develop novel nucleotide-competitive RT inhibitors.

Multidrug resistance in chronic myeloid leukaemia: how much can we learn from MDR-CML cell lines?

The hallmark of CML (chronic myeloid leukaemia) is the BCR (breakpoint cluster region)-ABL fusion gene. CML evolves through three phases, based on both clinical and pathological features: a chronic phase, an accelerated phase and blast crisis. TKI (tyrosine kinase inhibitors) are the treatment modality for patients with chronic phase CML. The therapeutic potential of the TKI imatinib is affected by BCR-ABL dependent an independent mechanisms. Development of MDR (multidrug resistance) contributes to the overall clinical resistance. MDR involves overexpression of ABC -transporters (ATP-binding-cassette transporter) among other features. MDR studies include the analysis of cancer cell lines selected for resistance. CML blast crisis is accompanied by increased resistance to apoptosis. This work reviews the role played by the influx transporter OCT1 (organic cation transporter 1), by efflux ABC transporters, molecules involved in the modulation of apoptosis (p53, Bcl-2 family, CD95, IAPs (inhibitors of apoptosis protein)], Hh and Wnt/β-catenin pathways, cytoskeleton abnormalities and other features described in leukaemic cells of clinical samples and CML cell lines. An MDR cell line, Lucena-1, generated from K562 by stepwise exposure to vincristine, was used as our model and some potential anticancer drugs effective against the MDR cell line and patients' samples are presented.

Treatment with dasatinib for chronic myeloid leukemia following imatinib-induced hepatotoxicity

Treatment with the tyrosine kinase inhibitor (TKI) imatinib for chronic myeloid leukemia in chronic phase (CML-CP) of disease may cause severe hepatotoxicity in rare cases. However, it remains unclear (1) how imatinib-induced hepatotoxicity should be treated; and (2) if and how TKI treatment can be resumed after recovery. We report a 32-year-old woman with CML-CP and histology confirmed imatinib-induced liver toxicity after 6 months of treatment. In this case, the early administration of corticosteroid therapy resulted in rapid and complete hepatic recovery, and treatment for CML-CP with the second generation TKI dasatinib was continued safely after recovery. Thus, dasatinib represents an option for maintaining therapeutic response in patients in whom continuation of imatinib is not possible due to its hepatic toxicity.

Myelodysplastic syndrome (MDS)-associated cytogenetic abnormalities in pediatric chronic myelogenous leukemia

Chronic myelogenous leukemia (CML) is very rare in the pediatric population. We report the case of a 2-year-old female with CML and concurrent myelodysplastic syndrome (MDS) associated cytogenetic abnormalities. The co-existence of t(9;22) and chromosomal deletions that are associated with MDS poses a unique diagnostic challenge. Given the reported association of t(9;22) and genomic instability, we hypothesize that the chromosomal deletions represent clonal evolution of the CML.

Andrographolide downregulates the v-Src and Bcr-Abl oncoproteins and induces Hsp90 cleavage in the ROS-dependent suppression of cancer malignancy

Andrographolide is a diterpenoid compound isolated from Andrographis paniculata that exhibits anticancer activity. We previously reported that andrographolide suppressed v-Src-mediated cellular transformation by promoting the degradation of Src. In the present study, we demonstrated the involvement of Hsp90 in the andrographolide-mediated inhibition of Src oncogenic activity. Using a proteomics approach, a cleavage fragment of Hsp90α was identified in andrographolide-treated cells. The concentration- and time-dependent induction of Hsp90 cleavage that accompanied the reduction in Src was validated in RK3E cells transformed with either v-Src or a human truncated c-Src variant and treated with andrographolide. In cancer cells, the induction of Hsp90 cleavage by andrographolide and its structural derivatives correlated well with decreased Src levels, the suppression of transformation, and the induction of apoptosis. Moreover, the andrographolide-induced Hsp90 cleavage, Src degradation, inhibition of transformation, and induction of apoptosis were abolished by a ROS inhibitor, N-acetyl-cysteine. Notably, Hsp90 cleavage, decreased levels of Bcr-Abl (another known Hsp90 client protein), and the induction of apoptosis were also observed in human K562 leukemia cells treated with andrographolide or its active derivatives. Together, we demonstrated a novel mechanism by which andrographolide suppressed cancer malignancy that involved inhibiting Hsp90 function and reducing the levels of Hsp90 client proteins. Our results broaden the molecular basis of andrographolide-mediated anticancer activity.

Experimental confirmation of new drug-target interactions predicted by Drug Profile Matching

We recently introduced Drug Profile Matching (DPM), a novel affinity fingerprinting-based in silico drug repositioning approach. DPM is able to quantitatively predict the complete effect profiles of compounds via probability scores. In the present work, in order to investigate the predictive power of DPM, three effect categories, namely, angiotensin-converting enzyme inhibitor, cyclooxygenase inhibitor, and dopamine agent, were selected and predictions were verified by literature analysis as well as experimentally. A total of 72% of the newly predicted and tested dopaminergic compounds were confirmed by tests on D1 and D2 expressing cell cultures. 33% and 23% of the ACE and COX inhibitory predictions were confirmed by in vitro tests, respectively. Dose-dependent inhibition curves were measured for seven drugs, and their inhibitory constants (Ki) were determined. Our study overall demonstrates that DPM is an effective approach to reveal novel drug-target pairs that may result in repositioning these drugs.

Galectins in hematological malignancies

PURPOSE OF REVIEW

Galectins are a family of lectin molecules that have emerged as key players in inflammation and tumor progresssion by displaying intracellular and extracellular activities. This review describes the recent advances on the role of galectins in hematological neoplasms.

RECENT FINDINGS

Galectin-1 and galectin-3 are the best studied galectins in oncohematology. Increased expression of galectin-1 has been associated with tumor progression in Hodgkin's lymphoma and chronic lymphocytic leukemia, whereas galectin-3 plays a supporting role in chronic myelogenous leukemia and multiple myeloma. Functional studies have assigned a key role for galectin-1 as a negative regulator of T-cell immunity in Hodgkin's lymphoma and cutaneous T-cell lymphoma. Of therapeutic interest is the development of agents with the capacity to interfere with galectin functions.

SUMMARY

Current knowledge indicates a key role for galectins in hematological neoplasms by favoring the growth and survival of tumor cells and facilitating tumor immune escape. Intervention using specific galectin inhibitors is emerging as an attractive therapeutic option to alter the course of these malignancies.

Potential of ponatinib to treat chronic myeloid leukemia and acute lymphoblastic leukemia

Development of BCR-ABL tyrosine kinase inhibitors (TKIs) have improved outcomes for patients diagnosed with chronic myeloid leukemia and Philadelphia chromosome positive acute lymphoblastic leukemia. However, resistance or intolerance to these TKIs still leaves some patients without many treatment options. One point mutation in particular, the T315I mutation, has been shown to be resistant to first and second generation TKIs. The third generation TKI, ponatinib, may provide an option for these patients. Ponatinib (Iclusig®), an orally available, pan-tyrosine kinase inhibitor has a unique binding mechanism allowing inhibition of BCR-ABL kinases, including those with the T315I point mutation. A Phase II study evaluated ponatinib in patients who were resistant or intolerant to nilotinib or dasatinib or patients who had the T315I mutation. In the Phase II study, ponatinib produced a major cytogenetic response in 54% of chronic phase chronic myeloid leukemia patients. It further achieved major hematologic response in 52% of patients in the accelerated phase, 31% of patients in the blast phase, and 41% of Philadelphia chromosome positive acute lymphoblastic leukemia patients. Ponatinib also showed efficacy in patients with the T315I mutation. Serious adverse events included arterial thrombosis, hepatotoxicity, cardiovascular risks, pancreatitis, hemorrhage, fluid retention, myelosuppression, rash, abdominal pain, and embryo–fetal toxicity. Due to the risk of these adverse events and potential drug interactions, the use of ponatinib must be carefully weighed against the benefits in treating patients who have limited treatment options.

A case of Philadelphia chromosome positive myeloproliferative neoplasm in a pregnant woman with unusual primary myelofibrosis features

Myeloproliferative neoplasms (MPNs) are traditionally separated into BCR-ABL-positive chronic myeloid leukemia (CML), and BCR-ABL-negative MPNs including primary myelofibrosis (PMF), essential thrombocythemia (ET), and so forth. One of the diagnostic requirements for PMF and ET is the absence of the Philadelphia chromosome, while its presence is almost universally indicative of CML. However, a diagnostic dilemma arises when Philadelphia chromosome-positive MPNs lack the majority of the typical features seen in CML. Some of these classic CML features include basophilIa, marked leukocytosis, neutrophils left-shift with myelocytes bulge, and "dwarf" megakaryocytes. Presented here is a case of a 32-year-old pregnant patient who did not have typical morphologic findings for CML, and yet the Philadelphia chromosome was positive. The patient demonstrated some pathologic features that are commonly presented in PMF that included bone marrow reticulin fibrosis, leukoerythroblastosis, splenomegaly, and increased serum lactate dehydrogenase.

Through the open door: Preferential binding of dasatinib to the active form of BCR-ABL unveiled by in silico experiments

Dasatinib is a second-generation BCR-ABL inhibitor approved for the treatment of patients with chronic myeloid leukemia, both in the frontline and in the imatinib-resistant/intolerant settings. The high affinity of dasatinib for the protein is currently assumed to result from its ability to bind both the active and inactive conformations of the BCR-ABL kinase. In the present work, using state of the art molecular simulation techniques we prove that dasatinib exhibits a highly selective preference for the active (open) BCR-ABL conformation. By using three different BCR-ABL conformations (active, inactive, and intermediate inactive) we show that, from a thermodynamic standpoint, the affinity of dasatinib for BCR-ABL drastically decreases in the order: active > alternative inactive > inactive, as a result of differential contributions from the single residues lining the kinase binding pocket and the concomitant stabilization/destabilization of the kinase hydrophobic spine. Molecule-pulling experiments also corroborate this trend as significantly lower forces and smaller times are required to extract dasatinib from its inactive BCR-ABL complexes with respect to the active complex counterparts. Importantly, our results support recent NMR solution results demonstrating no evidence of dasatinib bound to the inactive form of BCR-ABL.

ATM-dependent DNA damage-response pathway as a determinant in chronic myelogenous leukemia

Chronic myelogenous leukemia (CML) begins with an indolent chronic phase, and subsequently progresses to an accelerated or blastic phase. Although several genes are known to be involved in the progression to blastic phase, molecular mechanisms for the evolution toward blast crisis have not been fully identified. Oncogenic stimuli enforce cell proliferation, which requires DNA replication. Unscheduled DNA replication enforced by oncogenic stimuli leads to double strand breaks on DNA. We found the DNA damage-response pathway is activated in bone marrow of chronic-phase CML patients possibly due to an enforced proliferation signal by BCR-ABL expression. Since ataxia telangiectasia mutated (ATM) is a central player of the DNA damage-response pathway, we studied whether loss of this pathway accelerates blast crisis. We crossed Atm-knockout mice with BCR-ABL transgenic mice to test this hypothesis. Interestingly, the loss of one of the Atm alleles was shown to be enough for the acceleration of the blast crisis, which is supported by the finding of increased genomic instability as assayed by breakage-fusion-bridge (BFB) cycle formation. In light of these findings, the DNA damage-response pathway plays a vital role for determination of susceptibility to blast crisis in CML.

Lifestyle and dietary factors in relation to risk of chronic myeloid leukemia in the NIH-AARP Diet and Health Study

BACKGROUND

Aside from exposure to ionizing radiation and benzene, little is known about lifestyle risk factors for chronic myeloid leukemia (CML) in the general population.

METHODS

We examined the relation between lifestyle and dietary risk factors for CML in 493,188 participants (294,271 males and 198,917 females) aged 50 to 71 years who completed a baseline questionnaire in the National Institutes of Health-AARP Diet and Health Study in 1995 to 1996. Over a median of 10.5 years of follow-up, 178 incident cases of CML (139 males and 39 females) were ascertained from state registries. We used Cox proportional hazards models to estimate hazard ratios and 95% confidence intervals for exposures of interest, adjusting for potential confounding variables.

RESULTS

In multivariable analysis of all participants combined, female sex, years of education, and vigorous physical activity (HR for ≥3 times/week vs. <1 time/week 0.70; 95% CI, 0.49-0.99) were inversely associated with risk of CML, whereas smoking intensity (HR for smokers of ≥20 cigarettes per day vs. never smokers: 1.53; 95% CI, 1.03-2.27) and body mass (HR for BMI ≥ 30 vs. <25 kg/m(2) 1.46; 95% CI, 0.95-2.23) were associated with increased risk. A range of dietary factors was not associated with disease.

CONCLUSIONS

This study adds to the sparse information about lifestyle factors, which affect the risk of CML in the general population.

IMPACT

If these findings are confirmed, it would suggest that CML may be amenable to preventive strategies.

Multiplexed tyrosine kinase activity detection in cancer cells using a hydrogel immobilized substrate

Kinases play a key role in cellular signaling, and the overactivation or overexpression of these kinases has been linked to a variety of cancers. Tyrosine kinase inhibitors treat the mechanism of these cancers by targeting the specific kinases that are overactive. Some patients, however, do not respond to these inhibitors or develop resistance to these inhibitors during treatment. Additionally, even within cancers of the same tissue type, different kinases may be overactive in different patients. For example, some lung cancers overexpress epidermal growth factor receptor (EGFR) and respond to EGFR inhibitors, whereas other lung cancers do not overexpress EGFR and receive no benefit from this treatment. Even among patients exhibiting EGFR overexpression, some do not respond to EGFR kinase inhibitors because other kinases, such as Met kinase, are also overactivated. Here we describe a quantitative and specific multiplexed microfluidic assay using a hydrogel immobilized substrate for measuring the kinase activity of Met and Abl kinase from cancer cells. We immobilized kinase-specific substrates on macroporous hydrogel micropillars in microchannels. These microchannels were incubated with 6 μl of a kinase reaction solution containing cancer cell lysate, and we measured kinase activity via fluorescence detection of a phosphotyrosine antibody. We showed that the assay can specifically measure the activity of both Met and Abl kinase within one microchannel and has the potential to measure the activity of as many as five kinases within one microchannel. The assay also detected Met kinase inhibition from lysates of cancer cells grown in the Met kinase inhibitor PHA665752.