Chronic myeloid leukemia: current application of cytogenetics and molecular testing for diagnosis and treatment

Differential Expression of LMNA/C and Insulin Receptor Transcript Variants in Peripheral Blood Mononuclear Cells of Leukemia Patients

Background: Recent research has identified alternative transcript variants of LMNA/C (LMNA, LMNC, LMNAΔ10, and LMNAΔ50) and insulin receptors (INSRs) as potential biomarkers for various types of cancer. The objective of this study was to assess the expression of LMNA/C and INSR transcript variants in peripheral blood mononuclear cells (PBMCs) of leukemia patients to investigate their potential as diagnostic biomarkers. Methods: Quantitative TaqMan reverse transcriptase polymerase chain reaction (RT-qPCR) was utilized to quantify the mRNA levels of LMNA/C (LMNA, LMNC, LMNAΔ10, and LMNAΔ50) as well as INSR (IR-A and IR-B) variants in PBMCs obtained from healthy individuals (n = 32) and patients diagnosed with primary leukemias (acute myeloid leukemia (AML): n = 17; acute lymphoblastic leukemia (ALL): n = 8; chronic myeloid leukemia (CML): n = 5; and chronic lymphocytic leukemia (CLL): n = 15). Results: Only LMNA and LMNC transcripts were notably present in PBMCs. Both exhibited significantly decreased expression levels in leukemia patients compared to the healthy control group. Particularly, the LMNC:LMNA ratio was notably higher in AML patients. Interestingly, IR-B expression was not detectable in any of the PBMC samples, precluding the calculation of the IR-A:IR-B ratio as a diagnostic marker. Despite reduced expression across all types of leukemia, IR-A levels remained detectable, indicating its potential involvement in disease progression. Conclusions: This study highlights the distinct expression patterns of LMNA/C and INSR transcript variants in PBMCs of leukemia patients. The LMNC:LMNA ratio shows promise as a potential diagnostic indicator for AML, while further research is necessary to understand the role of IR-A in leukemia pathogenesis and its potential as a therapeutic target.

Feasibility of Qualitative Testing of BCR-ABL and JAK2 V617F in Suspected Myeloproliperative Neoplasm (MPN) Using RT-PCR Reversed Dot Blot Hybridization (RT-PCR RDB)

BACKGROUND

Defining the presence of BCR-ABL transcript in suspected myeloproliferative neoplasm is essential in establishing chronic myeloid leukemia. In the absence of BCR-ABL, the conventional diagnostic algorithm recommends JAK2 V617F mutation testing to support diagnosis of other MPN diseases such as polycythemia vera, essential thrombocythemia, and primary myelofibrosis. In certain cases of thrombocythemia, simultaneous upfront testing of both BCR-ABL and JAK2 may be desirable. We wanted to test the feasibility of multiplex detection of BCR-ABL transcript variants and JAK2 V617F mutation simultaneously using the reverse transcriptase polymerase chain reaction (RT-PCR)-based reverse dot-blot hybridization (RDB) method.

MATERIAL AND METHODS

Separate biotinylated RT-PCR primers were designed to amplify specific BCR-ABL transcripts and JAK2 V617F mutant alleles. Specific hybridization of RT-PCR products with arrays of membrane-bound probes followed by colorimetric development would allow simultaneous visualization of BCR-ABL and/or JAK2 mutant transcripts in a given specimen. To validate the RDB method, we used cDNA specimens previously referred to our laboratory for routine clinical testing of BCR-ABL and/or JAK2.

RESULTS

The limit of detection or analytical sensitivity of the RDB method using cDNA specimens was 0.5% and 6.25% in detecting BCR-ABL and JAK2 mutant transcripts, respectively. The diagnostic specificity and sensitivity to detect BCR-ABL and JAK2 were 100% and 92.3% (N = 38); and 100% and 100% (N = 27), respectively. RDB also detected BCR-ABL transcripts in 22% of JAK2 V617F mutation-positive samples (N = 14).

CONCLUSIONS

RT-PCR RDB is a promising qualitative multiplex method to detect BCR-ABL and JAK2 mutant transcripts simultaneously.

Chronic myeloid leukemia: past, present, future

The discovery of the Philadelphia chromosome in 1960, and of the BCR-ABL oncogene in 1984, enabled the development in subsequent years of a targeted therapy that revolutionized the treatment of chronic myeloid leukemia, thus changing its natural history. The use of imatinib resulted in a significant improvement of the prognosis and outcome of patients with chronic myeloid leukemia. However, the occurrence of mechanisms of resistance or intolerance precludes the eradication of the disease in some of the patients. Second-generation tyrosine-kinase inhibitors are efficient in most of these patients, except for those with T315I mutation. We present an overall review of chronic myeloid leukemia, with emphasis on the progress in its treatment.

Nucleostemin depletion induces post-g1 arrest apoptosis in chronic myelogenous leukemia k562 cells

PURPOSE

Despite significant improvements in treatment of chronic myelogenous leukemia (CML), the emergence of leukemic stem cell (LSC) concept questioned efficacy of current therapeutical protocols. Remaining issue on CML includes finding and targeting of the key genes responsible for self-renewal and proliferation of LSCs. Nucleostemin (NS) is a new protein localized in the nucleolus of most stem cells and tumor cells which regulates their self-renewal and cell cycle progression. The aim of this study was to investigate effects of NS knocking down in K562 cell line as an in vitro model of CML.

METHODS

NS gene silencing was performed using a specific small interfering RNA (NS-siRNA). The gene expression level of NS was evaluated by RT-PCR. The viability and growth rate of K562 cells were determined by trypan blue exclusion test. Cell cycle distribution of the cells was analyzed by flow cytometry.

RESULTS

Our results showed that NS knocking down inhibited proliferation and viability of K562 cells in a time-dependent manner. Cell cycle studies revealed that NS depletion resulted in G(1) cell cycle arrest at short times of transfection (24 h) followed with apoptosis at longer times (48 and 72 h), suggest that post-G1 arrest apoptosis is occurred in K562 cells.

CONCLUSION

Overall, these results point to essential role of NS in K562 cells, thus, this gene might be considered as a promising target for treatment of CML.

Microfluidic channel-assisted screening of hematopoietic malignancies

A simple microfluidic fluorescence in situ hybridization (FISH) device allowing accurate analysis of interphase nuclei in 1 hr in narrow channels is presented. Photolithography and fluorosilicic acid etching were used to fabricate microfluidic channels (referred to as FISHing lines) that allowed analysis of 10 samples on a glass microscope slide 0.2 µl of sample volume was used to fill a micro-channel, which resembled a 250-fold reduction compared to conventional FISH. FISH signals were comparable to conventional FISH, with 50-fold less probe consumption and 10-fold less time. Cells were immobilized in single file in channels just exceeding the diameter of the cells, and were used for minimal residual disease (MRD) analysis. To test the micro-channels for application in FISH, MRD was simulated by mixing K562 cells (an established chronic myeloid leukemia cell line) carrying the BCR/ABL fusion gene across 1:1 to 1:1,000 Jurkat cells (an established acute lymphoblastic leukemia cell line). The limit of detection was seen to be 1:100 cells and 1:1,000 cells for FISHing lines and conventional FISH, respectively; however, the conventional method seemed to over-score the presence of K562 cells. This may in part be attributed to FISHing lines practically eliminating the chance of duplicate screening of cells and hastened the time of screening, enhancing scoring of all cells within the channels. This was compared to 1 in 500 cells on the slide being analyzed with the conventional FISH.

Interpretation of cytogenetic and molecular results in patients treated for CML

The International Randomized Study of Interferon vs. STI571 (IRIS) trial that investigated the use of the tyrosine kinase inhibitor (TKI) imatinib (versus interferon) changed the treatment and outcome of chronic myeloid leukemia (CML). Long-term follow-up of IRIS patients has defined response parameters and methods of tracking residual disease with cytogenetic testing of bone marrow metaphases and molecular monitoring of BCR-ABL transcripts using quantitative reverse-transcriptase polymerase chain reaction. Cytogenetic and molecular responses are now considered useful surrogates for long-term outcome. Early and robust response to imatinib predicts positive long-term outcomes. However, 15-25% of patients fail initial treatment or become intolerant of imatinib and need increased doses or alternate treatment. Second-line treatment with the second-generation TKIs nilotinib and dasatinib have resulted in favorable rates of progression-free survival (PFS) and overall survival. Data from the ENESTnd (nilotinib) and DASISION (dasatinib) trials in newly diagnosed chronic-phase CML patients demonstrated more robust and rapid complete cytogenetic (77-80%) and major molecular responses (43-46%) at 12 months compared with imatinib (65-66% and 22-28%). The relationship between a complete cytogenetic response at 12 months and long-term PFS supports a role for second-generation TKIs as first-line treatment of newly diagnosed chronic-phase CML.

Chronic myeloid leukemia: cytogenetic methods and applications for diagnosis and treatment

Chronic myeloid leukemia (CML) is a clonal myeloproliferative disease caused by recombination between the BCR gene on chromosome 22 and the ABL1 gene on chromosome 9. This rearrangement generates the BCR-ABL1 fusion gene that characterizes leukemic cells in all CML cases. In about 90% of cases, the BCR-ABL1 rearrangement is manifest cytogenetically by the Philadelphia (Ph) chromosome, a derivative of the reciprocal translocation t(9;22)(q34;q11.2). For the remaining cases, recombination may be more complex, involving BCR, ABL1, and genomic sites on one or more other chromosomal regions, or it may occur cryptically within an apparently normal karyotype. Detection of the Ph and associated t(9;22) translocation is a recognized clinical hallmark for CML diagnosis. The disease has a natural multistep pathogenesis, and during chronic phase CML, the t(9;22) or complex variant is usually the sole abnormality. In 60-80% of cases, additional cytogenetic changes appear and often forecast progression to an accelerated disease phase or a terminal blast crisis. Because new frontline therapies such as imatinib specifically target the abnormal protein product of the BCR-ABL1 fusion gene to eliminate BCR-ABL1 positive cells, there is a new reliance on the cytogenetic evaluation of bone marrow cells at diagnosis, then at regular posttreatment intervals. Combined with other parameters, presence or absence of Ph-positive cells in the bone marrow is a powerful early indicator for clinical risk stratification. Cytogenetic changes detected at any stage during treatment, including in the BCR-ABL1-negative cells, may also provide useful prognostic information. Laboratory methods detailed here extend from initial collection of peripheral blood or bone marrow samples through cell culture with or without synchronization, metaphase or interphase harvest, hypotonic treatment and fixation, slide preparation for G-banding or fluorescent in situ hybridization (FISH), and final interpretation.

Quality control in FISH as part of a laboratory's quality management system

Quality control in the laboratory setting requires the establishment of a quality management system (QMS) that covers training, standard operating procedures, internal quality control, validation of tests, and external quality assessment (EQA). Laboratory accreditation through inspection by an external body is also desirable as this provides an effective procedure for assuring quality and also reassures the patient that the laboratory is working to acceptable international standards. The implementation of fluorescence in situ hybridisation (FISH) in the routine diagnostic laboratory requires rigorous quality control with attention to when it is appropriate to apply the technology, a systematic approach to the validation of probes, policies and procedures documenting the analytical validity of all FISH tests performed, technical procedures involved, and a comprehensive means of reporting results. Knowledge of the limitations of any FISH test is required in relation to the probe and/or tissue being examined, since errors of analysis and interpretation can result in incorrect patient management. A structured QMS with internal quality control and regular audits will minimise the error rate.

Utility of peripheral blood dual color, double fusion fluorescentin situhybridization forBCR/ABLfusion to assess cytogenetic remission status in chronic myeloid leukemia

The molecular signature of BCR-ABL fusion in chronic myeloid leukemia (CML) provides a unique tool for diagnosis and monitoring of tumor burden during therapy. The gold standard in this regard is conventional bone marrow cytogenetics. Peripheral blood fluorescent in situ hybridization (FISH) offers the possibility of a less invasive, more practical alternative method in terms of both cost and turnaround time. In the present study, we examined 296 paired samples from 65 patients with CML and demonstrate a tight correlation, in quantifying BCR-ABL burden between bone marrow cytogenetics, bone marrow dual color, double fusion (D-FISH), and peripheral blood D-FISH (P < 0.0001 for each). Furthermore, we demonstrate that peripheral blood D-FISH can be used as a surrogate for cytogenetic studies in monitoring cytogenetic remission status.

Detection of derivative 9 deletion by BCR-ABL fluorescence in-situ hybridization signal pattern to evaluate treatment response in CML patients

Background: To evaluate prognostic effect of submicroscopic deletions involving breakage and fusion points of the derivative chromosome 9 and 22 in chronic myeloid leukemia in untreated patients and their follow up samples to correlate with disease outcome. Methods: The study included 78 pretreatment (PT) samples from CML patients and 90 follow-up samples, classified as complete responders (CR, n=33), nonresponders (NR, n =54), and partial responder (PR, n=3) depending on the treatment status of the follow-up samples. Karyotype analysis was performed on metaphases obtained through short term cultures of bone marrow and blood. Detection of BCR-ABL fusion gene was performed using dual color dual fusion (D-FISH) translocation probes. Results: BCR-ABL fusion gene detection by D-FISH showed ABL-BCR deletion on derivative 9 in 47.8% of nonresponders which was higher as compared to pretreatment (11%). Mix D-FISH signal pattern was found in around 20% of pretreatment and non-responder samples. Average interval from chronic phase to blast crisis and accelerated phase was respectively 3.5 and 18 months and accelerated to blast crisis was 16.5 months from the time of diagnosis. The follow-up duration of 31 patients responded to therapy was significantly higher (p=0.0001) as compared to 45 patients who did not respond to therapy. Variant D-FISH signal pattern was seen at the time of diagnosis in patient who responded to therapy as well as those patients who did not respond to therapy. Conclusion: This is the first study from India reporting deletion in ABL, BCR, or ABL-BCR on derivative 9 did not correlate with response to therapy.

Molecular diagnosis and monitoring in the clinical management of patients with chronic myelogenous leukemia treated with tyrosine kinase inhibitors

The well-established molecular pathogenesis of chronic myelogenous leukemia (CML) and its consequences for laboratory testing and clinical management illustrate a classic paradigm for the importance of molecular diagnostics in targeted drug therapy. The success of the tyrosine kinase inhibitor (TKI), imatinib, as the currently recommended first-line treatment of early chronic phase CML has both fueled the need for timely and reproducible molecular testing of the BCR-ABL1 fusion transcript in diagnosis and monitoring as well as necessitated the detection of kinase domain mutations that confer resistance to this agent. As, ongoing research continues to refine guidelines for monitoring residual disease in patients undergoing TKI therapy, an understanding of molecular technologies and their interpretation is critical. This review summarizes the molecular strategies that are currently employed in the initial diagnosis and subsequent management of CML patients maintained on TKI therapy.

UVA radiation causes DNA strand breaks, chromosomal aberrations and tumorigenic transformation in HaCaT skin keratinocytes

The role of UVA-radiation-the major fraction in sunlight-in human skin carcinogenesis is still elusive. We here report that different UVA exposure regime (4 x 5 J/cm(2) per week or 1 x 20 J/cm(2) per week) caused tumorigenic conversion (tumors in nude mice) of the HaCaT skin keratinocytes. While tumorigenicity was not associated with general telomere shortening, we found new chromosomal changes characteristic for each recultivated tumor. Since this suggested a nontelomere-dependent relationship between UVA irradiation and chromosomal aberrations, we investigated for alternate mechanisms of UVA-dependent genomic instability. Using the alkaline and neutral comet assay as well as gamma-H2AX foci formation on irradiated HaCaT cells (20-60 J/cm(2)), we show a dose-dependent and long lasting induction of DNA single and double (ds) strand breaks. Extending this to normal human skin keratinocytes, we demonstrate a comparable damage response and, additionally, a significant induction and maintenance of micronuclei (MN) with more acentric fragments (indicative of ds breaks) than entire chromosomes particularly 5 days post irradiation. Thus, physiologically relevant UVA doses cause long-lasting DNA strand breaks, a prerequisite for chromosomal aberration that most likely contribute to tumorigenic conversion of the HaCaT cells. Since normal keratinocytes responded similarly, UVA may likewise contribute to the complex karyotype characteristic for human skin carcinomas.

Acute leukemia immunohistochemistry: a systematic diagnostic approach

CONTEXT

The diagnosis and classification of leukemia is becoming increasingly complex. Current classification schemes incorporate morphologic features, immunophenotype, molecular genetics, and clinical data to specifically categorize leukemias into various subtypes. Although sophisticated methodologies are frequently used to detect characteristic features conferring diagnostic, prognostic, or therapeutic implications, a thorough microscopic examination remains essential to the pathologic evaluation. Detailed blast immunophenotyping can be performed with lineage- and maturation-specific markers. Although no one marker is pathognomonic for one malignancy, a well-chosen panel of antibodies can efficiently aid the diagnosis and classification of acute leukemias.

OBJECTIVE

To review important developments from recent and historical literature. General immunohistochemical staining patterns of the most commonly encountered lymphoid and myeloid leukemias are emphasized. The goal is to discuss the immunostaining of acute leukemias when flow cytometry and genetic studies are not available.

DATA SOURCES

A comprehensive review was performed of the relevant literature indexed in PubMed (National Library of Medicine) and referenced medical texts. Additional references were identified in the reviewed manuscripts.

CONCLUSIONS

Immunophenotyping of blasts using an immunohistochemical approach to lymphoid and myeloid malignancies is presented. Initial and subsequent additional antibody panels are suggested to confirm or exclude each possibility in the differential diagnosis and a general strategy for diagnostic evaluation is discussed. Although the use of immunohistochemistry alone is limited and evaluation by flow cytometry and genetic studies is highly recommended, unavoidable situations requiring analysis of formalin-fixed tissue specimens arise. When performed in an optimized laboratory and combined with a careful morphologic examination, the immunohistochemical approach represents a useful laboratory tool for classifying various leukemias.

A multiplex PCR for improved detection of typical and atypical BCR-ABL fusion transcripts

RT-PCR is the method of choice for detecting BCR-ABL in CML and ALL. The three predominant mRNA transcripts found are e1a2 (in ALL), e13a2, and e14a2 (in CML and ALL). However, a number of "atypical"BCR-ABL transcripts (e1a3, e13a3, e14a3, e19a2, e6a2, e8a2, etc.) resulting from chromosomal breakpoints outside ABL intron 1 or BCR intron 1, 13 or 14, respectively, have been reported. These atypical transcripts may escape detection when using methods that are optimized to detect just the typical ones. We present here a novel, fast, and reliable multiplex PCR for improved detection of typical and atypical BCR-ABL transcripts.

Evaluation of the Cepheid GeneXpert BCR-ABL assay

Patients with chronic myeloid leukemia harbor the chromosomal translocation t(9;22), which corresponds to fusion of the BCR and ABL genes at the DNA level. The translated fusion product is an oncogenic protein with increased ABL tyrosine kinase activity causing cell transformation. To date, reverse transcriptase-polymerase chain reaction is considered the most sensitive method available for detecting low copy numbers of the BCR-ABL gene fusion. Recently, Cepheid introduced its GeneXpert-based assay for the identification of the BCR-ABL gene fusion in cells from blood samples. This system comprises a walk-away self-contained instrument that combines cartridge-based microfluidic sample preparation with reverse transcriptase-polymerase chain reaction-based fluorescent signal detection and BCR-ABL and ABL Ct (threshold cycle) determination. The difference between the BCR-ABL Ct and ABL Ct (DeltaCt) is expected to represent the ratio of the two populations of mRNAs and ultimately the percentage of neoplastic cells present. We tested whether this BCR-ABL fusion detection system could be used as a clinical diagnostic tool for monitoring patients with minimal residual disease of chronic myelogenous leukemia. We report similar performance characteristics, including limit of detection, specificity, sensitivity, and precision, of this automated BCR-ABL fusion detection system to those of a manual TaqMan reverse transcriptase-polymerase chain reaction-based test.

Guidance for fluorescence in situ hybridization testing in hematologic disorders

Fluorescence in situ hybridization (FISH) provides an important adjunct to conventional cytogenetics and molecular studies in the evaluation of chromosome abnormalities associated with hematologic malignancies. FISH employs DNA probes and methods that are generally not Food and Drug Administration-approved, and therefore, their use as analyte-specific reagents involves unique pre- and postanalytical requirements. We provide an overview of the technical parameters influencing a reliable FISH result and encourage laboratories to adopt specific procedures and policies in implementing metaphase and interphase FISH testing. A rigorous technologist training program relative to specific types of probes is detailed, as well as guidance for consistent interpretation of findings, including typical and atypical abnormal results. Details are provided on commonly used dual-fusion, extra signal, and break-apart probes, correct FISH nomenclature in the reporting of results, and the use of FISH in relation to other laboratory testing in the ongoing monitoring of disease. This article provides laboratory directors detailed guidance to be used in conjunction with existing regulations to successfully implement a FISH testing program or to assess current practices, allowing for optimal clinical testing for patient care.

The diagnostic interface between histology and molecular tests in myeloproliferative disorders

PURPOSE OF REVIEW

The sighting of the Philadelphia chromosome in 1960, later shown to harbor the BCR-ABL mutation in chronic myeloid leukemia, is arguably the most seminal contribution to molecular oncology. In the decades that followed, other cytogenetic and molecular disease markers have been described and effectively incorporated into routine diagnostic tests. This review discusses how this process is unfolding in myeloproliferative disorders.

RECENT FINDINGS

In 2003, a karyotypically-occult FIP1L1-PDGFRA was reported in a subset of patients with blood eosinophilia and bone marrow mastocytosis; this mutation has since joined several other molecular markers for eosinophilic (e.g. PDGFRbeta- and FGFR1-rearrangements) and mast cell (e.g. KITD816V) disorders. In 2005, JAK2V617F was described in polycythemia vera and other BCR-ABL myeloproliferative disorders; the particular discovery has already had a major impact on current diagnostic approaches in polycythemia vera. These remarkable molecular discoveries are both redefining and reinforcing the diagnostic role of bone marrow histopathology.

SUMMARY

Recent progress in the molecular pathogenesis of myeloproliferative disorders calls for a paradigm shift in traditional diagnostics, which is based on subjective technologies or assignment to a 'consensus'-based ever-changing list of inclusionary and exclusionary criteria. Routine clinical practice might be better served by diagnostic algorithms that incorporate molecular disease markers, which complement histological impression.

Leukemia: stem cells, maturation arrest, and differentiation therapy

Human myeloid leukemias provide models of maturation arrest and differentiation therapy of cancer. The genetic lesions of leukemia result in a block of differentiation (maturation arrest) that allows myeloid leukemic cells to continue to proliferate and/or prevents the terminal differentiation and apoptosis seen in normal white blood cells. In chronic myeloid leukemia, the bcr-abl (t9/22) translocation produces a fusion product that is an activated tyrosine kinase resulting in constitutive activation cells at the myelocyte level. This activation may be inhibited by imatinib mesylate (Gleevec, STI-571), which blocks the binding of ATP to the activated tyrosine kinase, prevents phosphorylation, and allows the leukemic cells to differentiate and undergo apoptosis. In acute promyelocytic leukemia, fusion of the retinoic acid receptor-alpha with the gene coding for promyelocytic protein, the PML-RAR alpha (t15:17) translocation, produces a fusion product that blocks the activity of the promyelocytic protein, which is required for formation of the granules of promyelocytes and prevents further differentiation. Retinoic acids bind to the retinoic acid receptor (RAR alpha) component of the fusion product, resulting in degradation of the fusion protein by ubiquitinization. This allows normal PML to participate in granule formation and differentiation of the promyelocytes. In one common type of acute myeloid leukemia, which results in maturation arrest at the myeloid precursor level, there is a mutation of FLT3, a transmembrane tyrosine kinase, which results in constitutive activation of the IL-3 receptor. This may be blocked by agents that inhibit farnesyl transferase. In each of these examples, specific inhibition of the genetically altered activation molecules of the leukemic cells allows the leukemic cells to differentiate and die. Because acute myeloid leukemias usually have mutation of more than one gene, combinations of specific inhibitors that act on the effects of different specific genetic lesions promises to result in more effective and permanent treatment.

Application of Genomics in Clinical Oncology

Genomics is a comprehensive study of the whole genome, genetic products, and their interactions. Human genome project has identified around 25,000-30,000 genes, and prevailing presence in tumor pathogenesis, high number of mutations, epigenetic changes, and other gene disorders have been identified. Microarrays technology is used for the analysis of these changes. Postgenome age has begun, and the initial results ensure the improvement of molecular tumor diagnostics and the making of a new taxonomic tumor classification, as well as the improvement, optimization and individualization of anti-tumor therapy. First genomic classifications have been made of leukemias, non-Hodgkin lymphoma, and many solid tumors. For example, 4 molecular types of breast carcinoma, three types of diffuse B cell lymphoma, two types of chromophobic renal carcinoma have been identified. Also, gene structures for favorable and unfavorable outcome in leukemia, breast cancer, prostate, bronchi, and other tumors have been identified. It is absolutely possible to diagnose the primary outcome of tumors with which standard tumor position may not be proved using standard diagnostic tools. Pharmacogenomic profiles have ensured better definition of interindividual differences during therapy using antineoplastic drugs and the decrease of their toxicity, as well as individual treatment approach and patient selection with which favorable clinical outcome is expected. Pharmacogenomics has impacted the accelerated development of target drugs, which have showed to be useful in practice. New genomic markers mtDNA, meDNA, and miRNA have been identified, which, with great certainty, help the detection and diagnostics of carcinoma. In the future, functional genomics in clinical oncology provides to gain knowledge about tumor pathogenesis; it will improve diagnostics and prognosis, and open up new therapeutic options.

Monitoring your patients with chronic myeloid leukemia

PURPOSE

Chronic myeloid leukemia (CML), a hematopoietic stem cell disorder, which sometimes presents with fatigue, hepato-splenomegaly, and weight loss but is sometimes asymptomatic, is discussed.

SUMMARY

Diagnosis is suspected on the observation of an increased white blood cell count and is confirmed by the presence of the Philadelphia (Ph) chromosome. CML progresses through a series of three defined stages with survival times of 3-5 years if untreated. The chromosomal translocation creating the Ph chromosome creates the BCR-ABL fusion protein, which is the initiating factor for CML. BCR-ABL is a constitutively active tyrosine kinase, which transforms hematopoietic stem cells through dysregulation of proliferation, apoptosis, differentiation, and cell adhesion. The transformation process is then accelerated by the accumulation of additional translocations. This fusion protein has been used clinically as a therapeutic target and a sensitive marker for measuring residual disease. Techniques, such as cytogenetic analysis of chromosomes, allow for the visualization of the Ph chromosome and additional translocations and abnormalities. The more sensitive fluorescent in situ hybridization assay can directly visualize the bcr-abl translocation through merged fluorescent tags. Polymerase chain reaction, the most sensitive of the assays, can be used to detect minute amounts of bcr-abl mRNA and this has made it possible to monitor and detect minimal residual disease recurrence and disease progression, thus greatly enhancing patient care.

CONCLUSION

A variety of monitoring techniques can be employed during CML therapy, providing degrees of quantifying disease burden or absence of disease.

Fluorescent in situ hybridization in the diagnosis, prognosis, and treatment monitoring of chronic myeloid leukemia

The unique molecular characteristic of chronic myeloid leukemia (CML), the disease-causing ABL (9q34) to BCR (22q11) translocation, has provided an invaluable tool for disease diagnosis and monitoring of treatment response. The traditional standard in this regard is bone marrow karyotype, also known as conventional cytogenetics (CC), which reveals a shortened chromosome 22, the Philadelphia chromosome, t(9;22)(q34;q11). CC in CML has also been effectively used for monitoring the response to drug therapy. However, this particular laboratory test misses submicroscopic BCR/ABL translocations and is suboptimal for minimal residual disease (MRD) assessment. Both fluorescence in situ hybridization (FISH) and reverse-transcriptase polymerase chain reaction (RT-PCR) feature higher sensitivity in terms of both diagnosis and MRD assessment in CML, compared to CC. Another advantage of these alternative tests is their effective applicability to peripheral blood specimens. The current review highlights the practical literature with respect to the use of FISH for CML whereas the use of RT-PCR has been extensively covered in recent communications.

Stem cell transplantation in patients with chronic myelogenous leukemia: when should it be used?

Hematopoietic stem cell transplantation has been a cornerstone of therapy for chronic myelogenous leukemia (CML) for more than 15 years and is still a standard treatment option for patients with CML. The advent of imatinib mesylate, an inhibitor of the molecular defect driving CML, the BCR-ABL tyrosine kinase, has rewritten treatment algorithms for this disease and has shifted focus away from allografting. Despite advances in stem cell transplantation, such as broader availability with the use of modified conditioning regimens, use of allografting has diminished. Also, the nearly universal patient exposure to imatinib or other kinase inhibitors before transplantation may affect the biology of the disease that is currently being treated with an allograft and ultimately may affect outcomes. Exceedingly high rates of meaningful and stable response with longer follow-up continue to drive enthusiasm for imatinib use, and understanding of resistance mechanisms has driven rapid investigation of second-generation tyrosine kinase inhibitors to address imatinib failure and suboptimal response. In most patients, imatinib reduces CML to a minimal residual disease state in which options to further deepen remission, such as immunotherapy, are sought; monitoring techniques and interpretation of response advance in parallel to meet demands; and uncertainty remains as a new natural history of CML is defined in an era of kinase inhibitor therapy. This review summarizes the state of transplant and nontransplant therapy for CML and discusses the decision making for patients with an aim to optimize the use of our best therapies for CML in an era of uncertainty.

Cancer Stem Cells and Differentiation Therapy

Cancers arise from stem cells in adult tissues and the cells that make up a cancer reflect the same stem cell --> progeny --> differentiation progression observed in normal tissues. All adult tissues are made up of lineages of cells consisting of tissue stem cells and their progeny (transit-amplifying cells and terminally differentiated cells); the number of new cells produced in normal tissue lineages roughly equals the number of old cells that die. Cancers result from maturation arrest of this process, resulting in continued proliferation of cells and a failure to differentiate and die. The biological behavior, morphological appearance, and clinical course of a cancer depend on the stage of maturation at which the genetic lesion is activated. This review makes a comparison of cancer cells to embryonic stem cells and to adult tis sue stem cells while addressing two basic questions: (1) Where do cancers come from?, and (2) How do cancers grow? The answers to these questions are critical to the development of approaches to the detection, prevention, and treatment of cancer.

Comparison between three molecular methods for detection of blood melanoma tyrosinase mRNA. Correlation with melanoma stages and S100B, LDH, NSE biochemical markers

BACKGROUND

The molecular monitoring of circulating tumor cells by reverse transcriptase-PCR (RT-PCR) for patients with melanoma, is still under debate. It may be affected by: a) pre-analytical variability, b) frequency of melanoma-associated gene transcripts and c) the reliability of the methods employed. Few commercial methods are available for the detection of tyrosinase mRNA in blood.

OBJECTIVE

Comparison between two RT-PCR-nested methods with a third one based on real-time methodology, for detection and quantitation of tyrosinase transcripts, respectively.

METHODS

Sixty-two melanoma patients with different AJCC stages and 20 healthy subjects were enrolled. All blood samples were extracted in duplicate with two different methods. Two nested-PCR methods (one commercial and one in house) plus a real time commercial kit were employed.

RESULTS

The two nested PCR methods employed were overimposable, specific and sensitive, at least in the stage III, where there was a concordance between sentinel lymph nodes detection and blood tyrosinase positivity. The different extraction methods did not affect the quality of results, while the commercial real-time kit cannot be used.

CONCLUSION

Tyrosinase mRNA detection may be therefore employed to monitor the melanoma patients over time in function of response to therapy.

How to interpret and pursue an abnormal complete blood cell count in adults

A complete blood cell count (CBC) is one of the most common laboratory tests in medicine. For example, at our institution alone, approximately 1800 CBCs are ordered every day, and 10% to 20% of results are reported as abnormal. Therefore, it is in every clinician's interest to have some understanding of the specific test basics as well as a structured action plan when confronted with abnormal CBC results. In this article, we provide practical diagnostic algorithms that address frequently encountered conditions associated with CBC abnormalities including anemia, thrombocytopenia, leukopenia, polycythemia, thrombocytosis, and leukocytosis. The objective is to help the nonhematologist recognize when a subspecialty consultation is reasonable and when it may be circumvented, thus allowing a cost-effective and intellectually rewarding practice.

Genetic testing in the myelodysplastic syndromes: molecular insights into hematologic diversity

The myelodysplastic syndromes (MDS) are associated with a diverse set of acquired somatic genetic abnormalities. Bone marrow karyotyping provides important diagnostic and prognostic information and should be attempted in all patients who are suspected of having MDS. Fluorescent in situ hybridization (FISH) studies on blood or marrow may also be valuable in selected cases, such as patients who may have 5q- syndrome or those who have undergone hematopoletic stem cell transplantation. The MDS-associated cytogenetic abnormalities that have been defined by karyotyping and FISH studies have already contributed substantially to our current understanding of the biology of malignant myeloid disorders, but the pathobiological meaning of common, recurrent chromosomal lesions such as del(5q), del(20q), and monosomy 7 is still unknown. The great diversity of the cytogenetic findings described in MDS highlights the molecular heterogeneity of this cluster of diseases. We review the common and pathophysiologically interesting genetic abnormalities associated with MDS, focusing on the clinical utility of conventional cytogenetic assays and selected FISH studies. In addition, we discuss a series of well-defined MDS-associated point mutations and outline the potential for further insights from newer techniques such as global gene expression profiling and array-based comparative genomic hybridization.