Characterization of Ph-negative abnormal clones emerging during imatinib therapy

The impact of toxic metal bioaccumulation on colorectal cancer: Unravelling the unexplored connection

Colorectal cancer is a major public health concern, with increasing incidence and mortality rates worldwide. Environmental factors, including exposure to toxic metals, such as lead, chromium, cadmium, aluminium, copper, arsenic and mercury, have been suggested to play a significant role in the development and progression of this neoplasia. In particular, the bioaccumulation of toxic metals can play a significant role in colorectal cancer by regulating biological phenomenon associated to both cancer occurrence and progression, such as cell death and proliferation. Also, frequently these metals can induce DNA mutations in well-known oncogenes. This review provides a critical analysis of the current evidence, highlighting the need for further research to fully grasp the complex interplay between toxic metal bioaccumulation and colorectal cancer. Understanding the contribution of toxic metals to colorectal cancer occurrence and progression is essential for the development of targeted preventive strategies and social interventions, with the ultimate goal of reducing the burden of this disease.

PI3K/mTOR dual-inhibition with VS-5584 enhances anti-leukemic efficacy of ponatinib in blasts and Ph-negative LSCs of chronic myeloid leukemia

Ponatinib is used for advanced treatment of chronic myeloid leukemia (CML), although low doses to prevent side effects do not suppress survival pathways and eradicate leukemia stem cells (LSCs). We evaluated the potential of ponatinib and PI3K/mTOR dual-inhibitor VS-5584 combination (PoVS) therapy to increase the anti-leukemic effects of ponatinib and investigated the underlying mechanisms at the molecular level. We measured the cytotoxicities of ponatinib, VS-5584, and PoVS (CCK-8 assay), and used the median-effect equation for combination analyses. We investigated the effects of inhibitory concentrations on apoptosis, cell viability and cell-cycle regulation (flow cytometry), protein levels (ELISA, Western blot), transcriptional activities (dual-luciferase reporter assay), gene expressions (qRT-PCR). VS-5584 exerted selective cytotoxic effects against CML and LSC cell lines. VS-5584 inhibited the PI3K/Akt/mTOR pathway, resulting in reduced cell viability, slightly induced caspase-independent apoptosis, prominent G₀/G₁ cell-cycle blockade that is not a consequence of quiescence. Normal hematopoietic stem cell line was the least affected. Moreover, ponatinib and VS-5584 mediated synergistic anti-leukemic effects on leukemic cells. VS-5584 reduced the ponatinib dose required to target leukemic cells. PoVS treatment inhibited PI3K/Akt/mTOR pathway more consistently than either of the two agents alone through reducing p-Akt, p-mTOR, p-S6K, p-PRAS40, p-S6. The subsequent downstream effects were an increase in C/EBP transcriptional activity and decreases in activities of E2F/DP1, Myc/Max, CREB, STAT3, NFκB, AP-1, Elk-1/SRF. Transcriptional regulation resulted in alterations in the expression levels of target mRNAs. Our results highlight PoVS can be a promising treatment strategy for eliminating CML cells and LSCs selectively, with the reduced ponatinib doses.

Clonal chromosomal aberrations in Philadelphia negative cells such as monosomy 7 and trisomy 8 may persist for years with no impact on the long term outcome in patients with chronic myeloid leukemia

The appearance of clonal chromosomal aberrations in Philadelphia negative cells (CCA/Ph-) during the treatment of chronic myeloid leukemia (CML) was recently confirmed. Importance of these findings has not been clearly defined. We present data on the time of appearance, persistence, size of the CCA/Ph- clone in terms of drugs used and hematological, cytogenetic and molecular response rates. The focus was on the peripheral blood cytopenias and myelodysplastic changes in the bone marrow microscopic evaluation. In 5 out of 155 (3,2%) CML patients, the persistent presence (up to nine years) of CCA/Ph- was found (monosomy 7 and trisomy 8 in unrelated clones in two patients treated with tyrosine kinase inhibitors; trisomy 8 in two patients on imatinib; trisomy 21 in one patient on interferon alfa treatment). Aberrations were present in median 24% Ph- cells in 3-15 subsequent analyses at different cytogenetic and molecular response time points. No evident myelodysplastic changes nor transformation to MDS/AML occurred in patients with CCA/Ph-. All the patients achieved major molecular response (MMR). It seems that CCA/Ph- presence does not affect the long term outcome in patients with chronic myeloid leukemia. Further complex monitoring of the CML patients with CCA/Ph- is still needed.

Transient monosomy 7 in a chronic myelogenous leukemia patient during nilotinib therapy: a case report

Tyrosine kinase inhibitor treated chronic myelogenous leukemia patients with monosomy 7 arising in Philadelphia chromosome negative (Ph−) cells tend to evolve into MDS/AML. However, monosomy 7 in Ph− cells can be a transient finding, and it is not an absolute indication of the emergence of a new myeloid malignancy.

Acute Myeloid Leukemia and Other Types of Disease Progression in Myeloproliferative Neoplasms

OBJECTIVES

This session of the Society for Hematopathology/European Association for Haematopathology workshop focused on disease progression in myeloproliferative neoplasms (MPNs).

METHODS

The session included typical and unusual presentations of chronic myelogenous leukemia (CML), BCR-ABL1 positive; Philadelphia chromosome-negative (Ph-neg) MPNs; and mastocytosis.

RESULTS

Cases of CML illustrated various manifestations of progression, with emphasis on criteria defining stages of the disease. Issues were discussed related to the patterns of recurrence in patients receiving tyrosine kinase inhibitor therapy, including leukemic transformation occurring in a Ph-neg clone. Ph-neg MPN cases highlighted diagnostic approaches used to establish accelerated and blast phases, including cases with significant myelofibrosis and when an adequate bone marrow aspirate smear is not available. The session also included rare cases of aggressive mastocytosis.

CONCLUSIONS

There was agreement that a definitive diagnosis can be challenging in the absence of documented review of prior diagnostic material and clinical history.

Transient presence of clonal chromosomal aberrations in Ph-negative cells in patients with chronic myeloid leukemia remaining in deep molecular response on tyrosine kinase inhibitor treatment

Advancements in treatment of chronic myeloid leukemia (CML) turned this formerly fatal neoplasm into a manageable chronic condition. Therapy with tyrosine kinase inhibitors (TKIs) often leads to significant reduction of disease burden, known as the deep molecular response (DMR). Herein, we decided to analyze the cohort of CML patients treated in our center with TKIs, who obtain and retain DMR for a period longer than 24 months. The aim of the study was to evaluate the frequency of clonal cytogenetic aberrations in Philadelphia-negative (Ph-) cells in patients with DMR during TKI treatment. The analyzed data was obtained during routine molecular and cytogenetic treatment monitoring, using G-banded trypsin and Giemsa stain (GTG) karyotyping and reverse transcription quantitative PCR. We noticed that approximately 50% of patients (28 of 55) in DMR had, at some follow-up point, transient changes in the karyotype of their Ph- bone marrow cells. In 9.1% of cases (5 of 55), the presence of the same aberrations was observed at different time points. The most frequently appearing aberrations were monosomies of chromosomes 19, 20, 21, and Y. Statistical analysis suggests that the occurrence of such abnormalities in CML patients correlates with the TKI treatment time.

Clonal cytogenetic abnormalities after tyrosine kinase inhibitor therapy in Ph+ ALL resolution after decitabine therapy

Mixed chimerism and presence of minimal residual disease after stem cell transplantation (SCT) usually predict leukemia recurrence. In Philadelphia chromosome positive (Ph+) leukemia tyrosine kinase inhibitors can restore remission. These agents can induce clonal cytogenetic abnormalities in the Philadelphia negative cell population (CCA/Ph-), which may rarely progress to acute myeloid leukemia. A child with Ph+ acute lymphoblastic leukemia showed mixed donor chimerism and persistent bcr-abl transcripts after a matched sibling SCT. There was no response to tyrosine kinase inhibitor (TKI) therapy, but she has remained hematologically normal for more than 5 years. CCA/Ph- was detected but resolved with hypomethylating therapy.

Telomere loss in Philadelphia-negative hematopoiesis after successful treatment of chronic myeloid leukemia: evidence for premature aging of the myeloid compartment

Telomere shortening, a well-known marker of aging and cellular stress, occurs under several conditions in the hematopoietic compartment, including aplastic anemia and following iatrogenic noxae. We decided to verify whether pathological telomere erosion also arises in restored Philadelphia-negative (Ph-negative) hematopoiesis following successful treatment of chronic myeloid leukemia (CML). Eighty-one CML patients in complete cytogenetic remission were compared to 76 age-matched healthy subjects. Myeloid cells of CML patients had shorter telomeres than controls (6521 bp vs 7233 bp, p<0.001). This difference was specific for the myeloid compartment, since it was not observed in lymphoid cells (6774 bp vs 6909 bp, p=0.620). Acquired Ph-negative cytogenetic abnormalities (p=0.010), lack of complete molecular remission (p=0.016) and age (p=0.013) were independent predictors of telomere shortening. Telomere dynamics were assessed over a median follow-up period of 22 months. We documented accelerated non-physiological ongoing telomere shortening in 17/59 CML patients (28%). Patients experiencing grade 2-4 hematological toxicity, during CML remission possessed significantly shorter telomeres compared to those lacking toxicity (p=0.005 for any toxicity, p=0.007 for anemia). CML patients suffer from significant and often ongoing telomere stress resulting in premature and selective aging of the myeloid compartment which might have long-term consequences on function and integrity of Ph-negative hematopoiesis.

Managing resistance in chronic myeloid leukemia

Chronic myeloid leukemia (CML) is a myeloproliferative disorder that affects 5000 new patients per year in the United States. Prior to 10 years ago, durable remission was rare and patients often underwent bone marrow transplantation with substantial morbidity and mortality. Fortunately, CML has been the epicenter of exciting advances in cancer therapy with the discovery of the Bcr-Abl gene fusion and the subsequent development of imatinib mesylate, a small molecule tyrosine kinase inhibitor, to target the kinase activity of the bcr-abl protein product. Despite unprecedented durability for complete hematologic, cytogenetic, and molecular responses seen with front-line imatinib therapy, many patients require alternative therapy because of drug intolerance, suboptimal response, primary resistance, secondary resistance, or progression to advanced phase disease. Further, up to 5% of patients present with advanced disease that does not sustain a durable response to tyrosine kinase inhibitors. Thus, up to one third of CML patients require alternate therapy. Chronic myeloid leukemia has become an exemplary model system for understanding molecular targeting and overcoming mechanisms of drug resistance. This review will discuss potential mechanisms of resistance and ongoing research into novel targets and agents for CML resistant to standard of care.

Factors influencing a second myeloid malignancy in patients with Philadelphia-negative -7 or del(7q) clones during tyrosine kinase inhibitor therapy for chronic myeloid leukemia

The detection of Philadelphia-negative (Ph(neg)) cells with non-random karyotypic abnormalities after tyrosine kinase inhibitor (TKI) therapy of chronic myeloid leukaemia (CML) can be associated with myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML). To our knowledge, however, there have been no studies on variables influencing the risk of MDS/AML in patients with specific Ph(neg) karyotypes. We systematically examined studies reporting -7 or del(7q) within Ph(neg) cells in TKI-treated CML patients, and abstracted clinical and cytogenetic data from individual reports into a standardized format for further analysis. Of 53 patients, 43 had Ph(neg) -7 clones [as the sole abnormality (-7(sole)) in 29, or with other clones (-7(dual)) in 14], and del(7q) was present in 10. A total of 16/51 evaluable patients, all with -7, transformed to MDS/AML. Transformation was more frequent (15/16 patients) within 6 months of Ph(neg) -7 detection rather than subsequently (P < 0.0001). At first detection after TKI therapy, Ph(neg) abnormal clones comprised ≥50% of Ph(neg) cells in a greater proportion of patients with -7 than del(7q) (P = 0.035). Upon comparing -7(sole) and -7(dual), the latter was likely to be transient (P = 0.004), and AML was frequently observed with persistent -7 clones (P = 0.03). By logistic regression analysis (n = 36), clone size (P = 0.017), time-to-detection longer than 15 months (P = 0.02), and CML response (P = 0.085) were associated with MDS/AML. Validation of these novel associations in registry-based studies will help develop predictive criteria that define the MDS/AML risk in individual patients.

Prognostic Significance of Treatment Response in CML in View of Current Recommendations for Treatment and Monitoring

The use of small-molecule kinase inhibitors has redefined the management of cancer. Chronic myelogenous leukaemia (CML) has become the paradigm for targeted cancer treatment. Imatinib has become the gold standard in the treatment of CML with excellent and durable responses and minimal side effects. Molecular diagnostics constitute an integral part of the routine monitoring. Results of cytogenetic analysis and quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) indicate suboptimal response or treatment failure and guide treatment. New Abl kinase inhibitors such as nilotinib or dasatinib are options after the failure of or intolerance to imatinib, and both are available for first-line treatment of newly diagnosed CML. This review focuses on the prognostic significance of achieving a response at specific time points in patients with CML treated with imatinib, nilotinib or dasatinib in view of available data and current treatment recommendations.

Myelodysplastic syndrome with Ph negative monosomy 7 chromosome following transient bone marrow dysplasia during imatinib treatment for chronic myeloid leukemia

We describe a 60-year-old Japanese patient with chronic myeloid leukemia (CML) who developed myelodysplastic syndrome (MDS) with Ph negative monosomy 7 chromosome following transient bone marrow dysplasia during imatinib treatment. Most cases that developed chromosomal abnormality in Ph negative cells during imatinib therapy were reported to have less clinical implications, while rare cases developed MDS/AML. The present case suggested that metaphase karyotype analysis and bone marrow examination should be performed for the long term follow-up under imatinib treatment in cases showing cytopenia. The results also suggested that monosomy 7 in Ph negative cells may be an indicator of a poor prognosis.

Molecular measurement of BCR-ABL transcript variations in chronic myeloid leukemia patients in cytogenetic remission

Background

The monitoring of BCR-ABL transcript levels by real-time quantitative polymerase chain reaction (RT-qPCR) has become important to assess minimal residual disease (MRD) and standard of care in the treatment of chronic myeloid leukemia (CML). In this study, we performed a prospective, sequential analysis using RT-qPCR monitoring of BCR-ABL gene rearrangements in blood samples from 91 CML patients in chronic phase (CP) who achieved complete cytogenetic remission (CCyR) and major molecular remission (MMR) throughout imatinib treatment.

Methods

The absolute level of BCR-ABL transcript from peripheral blood was serially measured every 4 to 12 weeks by RT-qPCR. Only level variations > 0.5%, according to the international scale, was considered positive. Sequential cytogenetic analysis was also performed in bone marrow samples from all patients using standard protocols.

Results

Based on sequential analysis of BCR-ABL transcripts, the 91 patients were divided into three categories: (A) 57 (62.6%) had no variation on sequential analysis; (B) 30 (32.9%) had a single positive variation result obtained in a single sample; and (C) 4 (4.39%) had variations of BCR-ABL transcripts in at least two consecutive samples. Of the 34 patients who had elevated levels of transcripts (group B and C), 19 (55.8%) had a < 1% of BCR-ABL/BCR ratio, 13 (38.2%) patients had a 1% to 10% increase and 2 patients had a >10% increase of RT-qPCR. The last two patients had lost a CCyR, and none of them showed mutations in the ABL gene. Transient cytogenetic alterations in Ph-negative cells were observed in five (5.5%) patients, and none of whom lost CCyR.

Conclusions

Despite an increase levels of BCR-ABL/BCR ratio variations by RT-qPCR, the majority of CML patients with MMR remained in CCyR. Thus, such single variations should neither be considered predictive of subsequent failure and nor an indication for altering imatinib dose or switching to second generation therapy. Changing of imatinib on the basis of BCR-ABL/BCR% sustained increase and mutational studies is a prudent approach for preserving other therapeutic options in imatinib-resistant patients.

Genetic analysis of dasatinib-treated chronic myeloid leukemia rapidly developing into acute myeloid leukemia with monosomy 7 in Philadelphia-negative cells

Despite the recent success of tyrosine kinase inhibitors (TKIs) in the treatment of chronic myeloid leukemia (CML), approximately 2-17% of patients develop clonal cytogenetic changes in the Philadelphia-negative (Ph(-)) cell population. A fraction of these patients, in particular those displaying trisomy 8 or monosomy 7, are at risk of developing a myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML). Consequently, there is a need to characterize the clinical features of such cases and to increase our understanding of the pathogenetic mechanisms underlying the emergence of clonal cytogenetic changes in Ph(-) cells. To date, most cases reported have received treatment with imatinib. Here we describe the case of a patient with CML who developed monosomy 7 in Ph(-) cells during dasatinib therapy. At 20 months after dasatinib initiation, the patient developed MDS, which rapidly progressed into AML. Genome-wide 500K SNP array analysis of the monosomy 7 clone revealed no acquired submicroscopic copy number changes. Given the strong association between monosomy 7 and mutation of genes involved in the RAS pathway in juvenile myelomonocytic leukemia, we also screened for pathogenetic variants in KRAS, NRAS, and PTPN11, but did not detect any changes.

Optimizing therapy for patients with chronic myelogenous leukemia in chronic phase

Identification of BCR-ABL as the defining leukemogenic event in chronic myelogenous leukemia (CML) revolutionized the treatment of the disease. Imatinib, a potent BCR-ABL inhibitor, is the standard of care for the first-line treatment of patients with chronic-phase CML because of its high long-term response rates and favorable tolerability profile compared with previous standard therapies. However, resistance to imatinib develops in 2% to 4% of patients annually. For patients with acquired cytogenetic resistance to standard-dose imatinib (400 mg daily), imatinib dose escalation (600-800 mg daily) is an excellent first option for managing patients and achieving cytogenetic responses. However, for patients with primary resistance to imatinib, hematologic disease recurrence, or emergent BCR-ABL kinase domain mutations, imatinib dose escalation may not be sufficient to control the disease. For these patients, the potent second-generation tyrosine kinase inhibitors dasatinib and nilotinib are available. Both agents provide effective therapeutic options for patients with imatinib resistance or intolerance. For the current overview, the authors reviewed the data supporting the use of both dasatinib and nilotinib in imatinib-resistant or imatinib-intolerant patients, and they have highlighted the future of CML therapy. Overall, the article is intended to offer physicians a comprehensive review of the current literature and to provide data supporting various treatment options for patients with CML throughout the course of imatinib therapy and beyond.

Chronic myeloid leukemia: an update of concepts and management recommendations of European LeukemiaNet

PURPOSE

To review and update the European LeukemiaNet (ELN) recommendations for the management of chronic myeloid leukemia with imatinib and second-generation tyrosine kinase inhibitors (TKIs), including monitoring, response definition, and first- and second-line therapy.

METHODS

These recommendations are based on a critical and comprehensive review of the relevant papers up to February 2009 and the results of four consensus conferences held by the panel of experts appointed by ELN in 2008.

RESULTS

Cytogenetic monitoring was required at 3, 6, 12, and 18 months. Molecular monitoring was required every 3 months. On the basis of the degree and the timing of hematologic, cytogenetic, and molecular results, the response to first-line imatinib was defined as optimal, suboptimal, or failure, and the response to second-generation TKIs was defined as suboptimal or failure.

CONCLUSION

Initial treatment was confirmed as imatinib 400 mg daily. Imatinib should be continued indefinitely in optimal responders. Suboptimal responders may continue on imatinb, at the same or higher dose, or may be eligible for investigational therapy with second-generation TKIs. In instances of imatinib failure, second-generation TKIs are recommended, followed by allogeneic hematopoietic stem-cell transplantation only in instances of failure and, sometimes, suboptimal response, depending on transplantation risk.

Secondary myelodysplastic syndrome in a patient with Philadelphia-positive acute lymphoblastic leukemia after achieving a major molecular response with hyperCVAD plus imatinib mesylate

The addition of imatinib to high-intensity chemotherapy has improved the outcome of patients with Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL). However, the possible long-term side effects of this combination are not yet known. Development of new clonal abnormalities in complete cytogenetic remission after treatment with imatinib has been reported in patients with chronic myeloid leukemia but not in patients with Ph-positive ALL. Here, we present a patient with Ph-positive ALL who received hyperCVAD plus imatinib and achieved hematologic, cytogenetic, and major molecular responses. The patient then developed myelodysplastic syndrome and solitary central nervous system relapse of ALL.