Altered microenvironmental regulation of leukemic and normal stem cells in chronic myelogenous leukemia

We characterized leukemia stem cells (LSC) in chronic phase chronic myelogenous leukemia (CML) using a transgenic mouse model. LSC were restricted to cells with long-term hematopoietic stem cell (LTHSC) phenotype. CML LTHSC demonstrated reduced homing and retention in the bone marrow (BM), related to decreased CXCL12 expression in CML BM, resulting from increased G-CSF production by leukemia cells. Altered cytokine expression in CML BM was associated with selective impairment of normal LTHSC growth and a growth advantage to CML LTHSC. Imatinib (IM) treatment partially corrected abnormalities in cytokine levels and LTHSC growth. These results were validated using human CML samples and provide improved understanding of microenvironmental regulation of normal and leukemic LTHSC and their response to IM in CML.     

Is it possible to discontinue imatinib mesylate therapy in Chronic Myeloid Leukemia patients with undetectable BCR/ABL? A case report and a review of the literature

Imatinib mesylate (IM) therapy leads to a complete cytogenetic response (CCyR) in 75–90% of Chronic Myeloid Leukemia (CML) patients in chronic phase, but only a small percentage of patients achieve complete molecular response (CMR). Very little is known about IM discontinuation. We report the case of a 20-years-old male patient in chronic phase CML who maintained undetectable BCR/ABL mRNA levels, despite IM discontinuation over a period of 15 months after achieving CMR. Our patient reached CCyR and CMR after 3 and 6 months of IM treatment, respectively. We also reviewed the published literature concerning cases of IM discontinuation.     

Imatinib (ST1571) provides only limited selectivity for CML cells and treatment might be complicated by silent BCR-ABL genes

Very promising results have been obtained in clinical trials on chronic-phase chronic myeloid leukemia (CP-CML) patients treated with imatinib mesylate (IM; Gleevecr, STI571), a BCR-ABL tyrosine kinase inhibitor. However, we found that IM caused considerable inhibition of normal hematopoietic progenitor cells upon treating control bone marrow (BM) cultures. In vitro IM treatment gave a decrease in the yield and size of colonies from BM of untreated CP-CML patients that was only two to three times that from the normal samples. Moreover, about 30% of myeloid progenitors (CFU-GM) from CML BM still formed colonies in the presence of IM, most of which had BCR-ABL RNA. About half of these treated colonies also displayed methylation of the internal ABL Pa promoter, a CML-specific epigenetic alteration, which was used in this study as a marker for BCR-ABL translocation-containing cells. However, ~5-8% of the treated or the untreated CML BM-derived colonies had no detectable BCR-ABL RNA by two or three rounds of RT-PCR despite being positive for the internal standard RNA and displaying hallmarks of CML, either t(9;22)(q34;ql 1) or ABL Pa methylation. Our results indicate that IM is only partially specific for CML progenitor cells compared to normal hematopoietic progenitor cells and suggest that some CML cells may have a silent BCR-ABL oncogene that could interfere with therapy.     

慢性髓性白血病的现代治疗

 伊马替尼（IM）以及二代酪氨酸激酶抑制剂（TKI）的问世不仅彻底改革了慢性髓性白血病（CML）的治疗模式, 也成为其他肿瘤发病机制和治疗研究的范例。 IM可使90 %以上慢性期患者获得血液学缓解,80 %以上的患者获得遗传学完全缓解（CCyR）及主要分子学缓解（MMoR）。明显延长无病生存期,使CML自然病程大为改观。然而,也存在目前难以克服的缺点：TKI并非疾病基因清除剂,对CML干细胞不敏感,获得CCyR／MMoR者仍需长期持续服用,小部分患者发生抗药或不耐受。现阶段的TKI 仍是根治CML的起始。     

Pegylated IFN-α2a combined to imatinib mesylate 600 mg daily can induce complete cytogenetic and molecular responses in a subset of chronic phase CML patients refractory to IFN alone or to imatinib 600 mg daily alone

This phase I/II study was designed to demonstrate the tolerance and the efficacy of a combination of pegylated interferon-α 2a to Imatinib mesylate (IM) 600 mg daily in cytogenetically IM-resistant but in CHR chronic phase CML patients. The combination was generally well tolerated in the 15 evaluable patients. A significant reduction of the Ph1⁺ BM metaphases was observed in these poor prognosis patients, with 2 long-term CCyR including 2 MMR. After a median follow-up of 43 months, 93% of patients are alive. The addition of PegIFNα2a to IM600 is feasible, and able to overcome resistance within this context.     

Cysteine‐rich protein 61 regulates the chemosensitivity of chronic myeloid leukemia to imatinib mesylate through the nuclear factor kappa B/Bcl‐2 pathway

Although the targeted tyrosine kinase inhibitor imatinib mesylate (IM) has achieved significant responses against CML in the clinical setting, a small proportion of patients fail to respond to IM treatment and their disease continues to progress, indicating resistance to IM therapy. As a secreted extracellular matrix protein, cysteine‐rich protein 61 (Cyr61) plays an important role in the resistance of solid tumors to chemotherapy, but its role in CML is unclear. In the present study, we observed that Cyr61 levels were upregulated in the plasma and bone marrow (BM) of patients with CML as well as in K562 cells. This upregulation of Cyr61 significantly decreased IM‐induced cellular apoptosis of K562 cells through nuclear factor kappa B/B‐cell lymphoma 2 pathways. Inhibition of Cyr61 restored the chemosensitivity of K562 cells to IM both in vitro and in vivo. Thus, our results showed for the first time that Cyr61 plays an important role in regulating the chemosensitivity of CML cells to IM, suggesting that selectively targeting Cyr61 directly or its relevant effector pathways may provide potential value in improving the clinical response of patients with CML to IM treatment.     

Heterogeneity in detecting Abl kinase mutations and better sensitivity using circulating plasma RNA.

Most studies test for mutations in the kinase domain of the abl gene in chronic myeloid leukemia (CML) using peripheral blood (PB) cells. Frequently, progression of the disease manifests with increased blasts in bone marrow (BM) and not in PB. Simultaneous analysis of plasma, PB cells and BM cells from 41 imatinib-resistant CML patients showed mutations in 63% of PB cells and 68% of plasma or BM cells (P = 0.04). In discordant patients, 13 mutations were detected in plasma, 11 in BM cells and 9 in PB cells. The T315I mutation was detected in plasma and BM but not PB cells in one patient. We detected no mutations in the plasma of 45 previously untreated CML patients, but two of these patients showed mutations in plasma and not cells by 9 months on therapy. Circulating plasma mRNA is a reliable alternative to BM mRNA for detecting ABL mutations.     

Nilotinib as a second-line treatment for chronic myeloid leukemia

Chronic myeloid leukemia(CML)is a clonal disease of the hematopoietic stem cells that is characterized by excessive proliferation, but retains of the capacity for differentiation duringthe chronic phase of the disease. This phase is followed after 4-6 years by rapid progression, an accelerated phase, and consequently a fatal acute leukemia a blast crisis. The hallmark abnormality of CML is the Philadelphia chromosome that generates a BCR-ABL fusion gene, resulting in the expression of a leukemia-specific oncoprotein, Bcr-Abl. Bcr-Abl is a potent tyrosine kinase and plays a central role in CML pathogenesis. Recently, the treatment of CML has been revolutionized by the introduction of imatinib mesylate(IM). With daily IM treatment, more than 80% of chronic-phase CML patients achieve a complete cytogenetic response. Nevertheless, a small percentage of CML patients are primarily refractory or acquire secondary resistance against IM. Nilotinib is a highly selective Abl kinase inhibitor that possesses greater potency and selectivity for Abl kinase than IM. In addition to being more potent than IM against wild-type BCR-ABL, nilotinib is significantly active against many IM-resistant BCR-ABL mutants. In preclinical studies, nilotinib has produced hematologic and cytogenetic responses in CML patients, with either IM resistance or IM intolerance. As second-line treatment, both nilotinib and dasatinib may be used in case of suboptimal response or failure, which is defined in the efficacy criteria of the European Leukemia Net Consensus. The choice of second-generation tyrosine kinase inhibitors may be made after the mutation analyses of the kinase domain. It is recommended that nilotinib or dasatinib whichever was shown to be active against the specific mutation, should be chosen for treatment. For patients with no mutations or patients with IM intolerance, it is recommended that either second-generation tyrosine kinase inhibitor be chosen, based on the patient's disease history.     

EFFECTS OF IFN-a COMBINED WITH IL-6 ON GROWTH AND EXPRESSION OF THE GENES RELATED TO CELL-GROWTH AND APOPTOSIS OF BONE MARROW CELLS FROM PATIENTS WITH CML

CML is a clonal myeloproliferative disorder. The Philadelphia chromosome (ph) is the cytogenetic hall-mark of this disease.[1] The ph chromosome translocation [t(9; 22) (q34; qll)] results in the creation of a hybrid bcr-abl fusion gene and forms an abnormal 210-kD protein (p210bcr-abl) with increased tyrosine kinase activity.[2,3] These molecular changes were thought to play a significant role in leukemogenesis. p210bcr-abl confers a growth advantage on ph-positive CML cells over normal he…     

Neuropilin-1某因在髓细胞白血病和正常人骨髓基质细胞中的表达(英文)

目的了解 neuropilin-1(NP-1)基因在髓细胞白血病(AML 和 CML)患者及正常人骨髓基质细胞中的表达情况。方法收集12例 AML、14例 CML 和20例正常对照骨髓标本,分离单个核细胞。进行体外长期培养,收集贴壁细胞(骨髓基质细胞)。利用逆转录-聚合酶链反应分别检测3组骨髓基质细胞中 NP-1基因的表达。结果成功建立了 AML、CML 和正常人骨髓基质细胞培养方法,NP-1基因在 AML、CML 骨髓基质细胞中的表达率分别为47.1%和50%,明显低于正常对照(85%)。结论 NP-1基因可表达于部分 AML、CML 和大部分正常人的骨髓基质细胞中,其在髓细胞白血病患者骨髓基质细胞中的低表达,可能与其调节造血功能异常有关。     

Neuropilin-1基因在髓细胞白血病和正常人骨髓基质细胞中的表达

目的了解neuropilin-1(NP-1)基因在髓细胞白血病(AML和CML)患者及正常人骨髓基质细胞中的表达情况。方法收集12例AML、14例CML和20例正常对照骨髓标本,分离单个核细胞。进行体外长期培养,收集贴壁细胞(骨髓基质细胞)。利用逆转录-聚合酶链反应分别检测3组骨髓基质细胞中NP-1基因的表达。结果成功建立了AML、CML和正常人骨髓基质细胞培养方法,NP-1基因在AML、CML骨髓基质细胞中的表达率分别为47.1%和50%,明显低于正常对照(85%)。结论NP-1基因可表达于部分AML、CML和大部分正常人的骨髓基质细胞中,其在髓细胞白血病患者骨髓基质细胞中的低表达, 可能与其调节造血功能异常有关。     

Late Responses in Patients With Chronic Myeloid Leukemia Initially Refractory to Tyrosine Kinase Inhibitors

BackgroundThe introduction of tyrosine kinase inhibitor (TKI) therapy has dramatically improved outcomes for patients with chronic myeloid leukemia (CML); however, the prognosis for those who do not meet treatment milestones remains guarded. Here, we report our experience of patients with CML treated at a single center who did not achieve a complete cytogenetic response (CCyR) at 24 months.MethodsWe retrospectively evaluated 305 patients who were diagnosed with CML at the University of Michigan between 2001 and 2014 and were treated with TKIs. We assessed rates of CCyR at 24 months correlated to clinical outcomes.ResultsThe majority of patients (79%) achieved CCyR at 24 months and were classified as responders. At a median follow-up of 8.1 years from TKI initiation, overall survival among responders was significantly greater than nonresponders (93% vs. 85%, P < .001). Progression to blast phase was more common in nonresponders (1.9% vs. 10.4%, P = .004). However, 34% of nonresponders (at 24 months) went on to achieve CCyR with continued TKI therapy.ConclusionHere, we re-demonstrate the importance of early CCyR in predicting survival and prevention of progression to blast phase. In addition, late CCyR appears to have prognostic implications, and continued TKI therapy with the goal of achieving a later CCyR may be a reasonable strategy in patients with limited alternate treatment options.     

Growth inhibition of imatinib-resistant CML cells with the T315I mutation and hypoxia-adaptation by AV65--a novel Wnt/β-catenin signaling inhibitor

We investigated the effect of a novel Wnt/β-catenin signaling inhibitor, AV65 on imatinib mesylate (IM)-sensitive and -resistant human chronic myeloid leukemia (CML) cells in vitro. AV65 inhibited the proliferation of various CML cell lines including T315I mutation-harboring cells. AV65 reduced the expression of β-catenin in CML cells, resulting in the induction of apoptosis. Moreover, AV65 inhibited the proliferation of hypoxia-adapted primitive CML cells that overexpress β-catenin. The combination of AV65 with IM had a synergistic inhibitory effect on the proliferation of CML cells. These findings suggest that AV65 could be a novel therapeutic agent for the treatment of CML.     

Diagnosis and Monitoring of Chronic Myeloid Leukemia: Chiang Mai University Experience

Background: A diagnosis of chronic myeloid leukemia (CML) is made on discovery of the presence of a Philadelphia (Ph) chromosome. The success of the treatment of this form of leukemia with tyrosine kinase inhibitor (TKI) is monitored by reduction of the Ph chromosome. Objective: To compare the role of conventional cytogenetic (CC) methods with a real time quantitative polymerase chain reaction (RQ-PCR) and fluorescence in situ hybridization (FISH) for diagnosis and treatment monitoring of CML patients. The secondary outcome was to analyze the treatment responses to TKI in CML patients. Materials and Methods: This was a retrospective study of CML patients who attended the Hematology clinic at Chiang Mai University Hospital from 2005-2010. Medical records were reviewed for demographic data, risk score, treatment response and the results of CC methods, FISH and RQ-PCR. Results: One hundred and twenty three cases were included in the study, 57.7% of whom were male with a mean age of 46.9 years. Most of the patients registered as intermediate to high risk on the Sokal score. At diagnosis, 121 patients were tested using the CC method and 118 (95.9%) were identified as positive. Five patients failed to be diagnosed by CC methods but were positive for BCR-ABL1 using the FISH method. Imatinib was the first-line treatment used in 120 patients (97.6%). In most patients (108 out of 122, 88.5%), a complete cytogenetic response (CCyR) was achieved after TKI therapy and in 86 patients (70.5%) CCyR was achieved long term by the CC method. Five out of the 35 analyzed patients in which CCyR was achieved by the CC method had a positive FISH result. Out of the 76 patients in which CCyR was achieved, RQ-PCR classified patients to only CCyR in 17 patients (22.4%) with a deeper major molecular response (MMR) in 4 patients (5.3%) and complete molecular response (CMR) in 55 patients (72.4%). In the case of initial therapy, CCyR was achieved in 95 patients (79.1%) who received imatinib and in both patients who received dasatinib (100%). For the second line treatment, nilotinib were used in 30 patients and in 19 of them (63.3%) CCyR was achieved. In half of the 6 patients (50%) who received dasatinib as second line or third line treatment CCyR was also achieved. Conclusions: CML patients had a good response to TKI treatment. FISH could be useful for diagnosis in cases where CC analysis failed to detect the Ph chromosome. RQ-PCR was helpful in detecting any residual disease and determining the depth of the treatment response at levels greater than the CC methods.     

Leukemic spleen cells are more potent than bone marrow-derived cells in a transgenic mouse model of CML

Spleen size ranks among the most important risk factors in chronic myeloid leukemia (CML), but the pathogenic mechanisms of splenic hematopoiesis in CML remain poorly defined. Here, we studied the biology of Bcr-Abl positive leukemia-initiating cells in the spleen, using an inducible transgenic mouse model of CML. Disease kinetics showed greater increases of immature leukemic cells in spleen vs bone marrow (BM). To assess how Bcr-Abl alters the behavior of spleen-derived CML cells, we transplanted these cells either before ('pre-uninduced') or 44 days after ('pre-induced') expression of the oncogene. Mice transplanted with pre-induced spleen cells showed significantly increased neutrophilia and splenomegaly compared with mice receiving pre-uninduced spleen cells, suggesting that Bcr-Abl expression in the donors had increased splenic tumor burden. However, pre-induction also altered the biology of these cells, as shown by a striking increase in erythropoietic potential. These results differ from those of BM-derived CML stem cells where pre-induction of Bcr-Abl had previously been shown to decrease disease transplantability. Moreover, splenic cells were less sensitive to imatinib than BM cells. In conclusion, Bcr-Abl alters the biology of splenic leukemic stem cells by a cell-autonomous mechanism, but the disease phenotype is also influenced by the microenvironment of these cells.     

高三尖杉酯碱增强慢性粒细胞白血病细胞对于伊马替尼敏感性的研究*

目的: 研究高三尖杉酯碱（HHT）增强慢性粒细胞白血病（CML）细胞对伊马替尼（IM）敏感性的机制。 方法: 采集1例CML患者骨髓血标本,经体外筛选、克隆建立人白血病细胞株NPHA1（初治）和NPHA2（复发）。RNA干扰NPHA2细胞的EphB4蛋白表达,建立NPHA2-EphB4-sh细胞株。 结果: 与NPHA1细胞相比,耐IM的NPHA2细胞中EphB4过表达;在NPHA2-EphB4-sh细胞中,EphB4表达显著低于NPHA1细胞和NPHA2细胞（P<0.001）。NPHA2细胞对IM有明显耐药性（IC₅₀=5.45 mg/L）,但NPHA2-EphB4-sh对IM敏感性增加（IC₅₀=0.93 mg/L,P<0.001）。HHT与IM共处理后,NPHA2细胞对IM的IC50值降至1.17 mg/L（P<0.001）。蛋白磷酸化测定表明HHT抑制了EphB4/RhoA通路表达。 结论: EphB4/RhoA是一个新的IM耐药途径。HHT通过抑制EphB4/RhoA途径,使IM治疗获得优势。      

Evaluation of residual CD34+Ph+ progenitor cells in chronic myeloid leukemia patients who have complete cytogenetic response during first‐line nilotinib therapy

BACKGROUND:

Compared with imatinib, nilotinib is a potent breakpoint cluster region/v‐abl Abelson murine leukemia viral oncogene (bcr‐abl) kinase inhibitor, and it induces higher rate and rapid complete cytogenetic response (CCyR), yet no clinical data are available regarding its efficacy against chronic myeloid leukemia (CML) stem cells. Earlier studies demonstrated that clusters of differentiation 34–positive, Philadelphia chromosome–positive (CD34⁺Ph⁺) cells are detectable in about 45% of patients with CML, despite being on long‐term imatinib therapy and having achieved sustained CCyR.

METHODS:

CD34⁺ cells from bone marrow of de novo CML patients in the chronic phase (n = 24) treated with nilotinib (median duration of therapy, 22 months) were isolated and scored for BCR‐ABL by fluorescent in situ hybridization (FISH) analysis. Similar analysis was also performed in 5 de novo CML chronic phase patients who achieved CCyR within 3 months of nilotinib therapy.

RESULTS:

FISH evaluation of a median of 100 CD34⁺ nuclei per patient revealed that only 1 of 20 (5%) evaluable patients showed residual Ph⁺ progenitor cells. In this patient, just 1 of 140 (0.7%) CD34⁺ interphase nuclei was found to be positive for BCR‐ABL. Surprisingly, no CD34⁺Ph⁺ cells were found even in those 5 patients evaluated after 3 months of nilotinib treatment.

CONCLUSIONS:

This study assessed for the first time the persistence of CD34⁺Ph⁺ cells during nilotinib first‐line treatment. Preliminary results showed that in patients in CCyR, even after short‐term nilotinib therapy, residual leukemic progenitors are very rarely detected compared with imatinib‐treated CCyR patients. It is yet to be determined if these findings will have an impact in the path to a cure of CML with tyrosine kinase inhibitors. Cancer 2012. © 2012 American Cancer Society.     

Residual normal stem cells can be detected in newly diagnosed chronic myeloid leukemia patients by a new flow cytometric approach and predict for optimal response to imatinib

Insensitivity of chronic myeloid leukemia (CML) hematopoietic stem cells to tyrosine kinase inhibitors (TKIs) prevents eradication of the disease and may be involved in clinical resistance. For improved treatment results more knowledge about CML stem cells is needed. We here present a new flow cytometric approach enabling prospective discrimination of CML stem cells from their normal counterparts within single-patient samples. In 24 of 40 newly diagnosed CML patients residual normal CD34(+)CD38(-) stem cells could be identified by lower CD34 and CD45 expression, lower forward/sideward light scatter and by differences of lineage marker expression (CD7, CD11b and CD56) and of CD90. fluorescent in situ hybridization (FISH) analysis on Fluorescence-activated cell sorting sorted cells proved that populations were BCR-ABL positive or negative and long-term liquid culture assays with subsequent colony forming unit assays and FISH analysis proved their stem cell character. Patients with residual non-leukemic stem cells had lower clinical risk scores (Sokal, Euro), lower hematological toxicity of imatinib (IM) and better molecular responses to IM than patients without. This new approach will expand our possibilities to separate CML and normal stem cells, present in a single bone marrow or peripheral blood sample, thereby offering opportunities to better identify new CML stem-cell-specific targets. Moreover, it may guide optimal clinical CML management.