[Expression and Clinical Significance of DNMT in Patients with Chronic Myeloid Leukemia]

OBJECTIVE

To investigate the expression and clinical significance of DNA methyltransferases (DNMT) mRNA in patients with chronic myeloid leukemia (CML).

METHODS

The expression levels of DNMT mRNA in mononucllear cells (MNC) of bone marrow or in peripheral blood of 93 CML patients in 3 different phases and 10 normal controls (NC) were detected by SYBR Green flurescent quatitative PCR.

RESULTS

The relative expression levels of DNMT1 mRNA in NC, chronic phase CML (CML-CP), accelerated phase (CML-AP) and blastic phase (CML-BP) were 1.45 ± 0.22, 1.83 ± 0.63, 2.95 ± 0.87 and 3.24 ± 1.39 resectively. The expression of DNMT1 mRNA showed no statistically significant difference between CML-CP and NC (P = 0.28). The expression of DNMT1 mRNA in advanced stages (including CML-AP and CML-BP) of CML obviously increased in comparison with CML-CP and NC (P < 0.05). The expression of DNMT1 mRNA in CML-AP was not significantly different from that in CML-BP (P = 0.336). The relative expression levels of DNMT3a mRNA in NC, CML-CP, CML-AP and CML-BP groups were 1.29 ± 0.34, 1.34 ± 0.46, 2.33 ± 1.05 and 3.18 ± 1.23 resectively. And the expression levels of DNMT3a mRNA were not statistically significantly different between CML-CP and NC (P = 0.844). The results showed that the expression of DNMT3a mRNA in the advanced phase of CML significantly increased in comparison with that in CML-CP and NC (P < 0.05). Meanwhile, the expression of DNMT3a mRNA in CML-AP was not different from that in CML-BP (P = 0.304). The relative expression levels of DNMT3b mRNA in NC, CML-CP, CML-AP and CML-BP groups were 1.37 ± 0.31, 16.41 ± 22.50, 9.36 ± 5.50 and 12.17 ± 13.44 resectively. It was also found that the level of DNMT3b mRNA in CML significantly increased in comparison with NC (P < 0.05), and that the between the 3 different phase of CML was not statistically significantly different (P >0.05).

CONCLUSION

The expression of DNMT mRNA increases in advanced CML as compared with normal controls and CML-CP, and the increased levels of DNMT mRNA probably correlate with disease progression in CML.

Towards a Molecular Understanding of the Link between Imatinib Resistance and Kinase Conformational Dynamics

Due to its inhibition of the Abl kinase domain in the BCR-ABL fusion protein, imatinib is strikingly effective in the initial stage of chronic myeloid leukemia with more than 90% of the patients showing complete remission. However, as in the case of most targeted anti-cancer therapies, the emergence of drug resistance is a serious concern. Several drug-resistant mutations affecting the catalytic domain of Abl and other tyrosine kinases are now known. But, despite their importance and the adverse effect that they have on the prognosis of the cancer patients harboring them, the molecular mechanism of these mutations is still debated. Here by using long molecular dynamics simulations and large-scale free energy calculations complemented by in vitro mutagenesis and microcalorimetry experiments, we model the effect of several widespread drug-resistant mutations of Abl. By comparing the conformational free energy landscape of the mutants with those of the wild-type tyrosine kinases we clarify their mode of action. It involves significant and complex changes in the inactive-to-active dynamics and entropy/enthalpy balance of two functional elements: the activation-loop and the conserved DFG motif. What is more the T315I gatekeeper mutant has a significant impact on the binding mechanism itself and on the binding kinetics.

[A multicenter comparison study on the detection of BCR-ABL tyrosine kinase domain point mutation]

OBJECTIVE

To investigate the accuracy and consistency of the detection of BCR-ABL tyrosine kinase domain point mutation among different laboratories.

METHODS

Every one of 6 laboratories prepared 10 cDNA samples from tyrosine kinase inhibitors resistant BCR-ABL (P210 or P190) positive patients'bone marrow or peripheral blood. Each cDNA sample was divided into 6 aliquots and delivered to the laboratories. All 6 laboratories tested BCR-ABL point mutations of 60 samples according to their own protocols. Peking University People's Hospital analyzed the comparison results based on both the reports and sequencing chromatogram from all laboratories.

RESULTS

All laboratories reported the same nucleotide and corresponding amino acid mutations in 37 samples (61.7%）. Of 60 samples, 53 had confirmed mutation types, and a total of 23 types were included; 1 had no mutation; mutation types of 6 samples could not be determined because of the big differences among chromatograms from different laboratories. Low percentages of mutants were significantly related to results inconsistency (P=0.008). Inconsistent result of one sample was caused by the unique chromatogram of the mutant L248V, and one by the non-coverage amplification of PCR product from different laboratories. Amplification was failed in 3 samples. Testing or sequencing mistakes occurred in 7 samples. The differences in the mutant percentages among laboratories were less than 20% in the 80.6% of samples with confirmed results. Low internal control gene copies (ABL<10 000) were significantly related to both failed amplification and big differences among chromatograms from different laboratories (P=0.005 and <0.001, respectively).

CONCLUSION

Problems in the clinical routine detection of BCR-ABL point mutation could be exposed and improvement could be achieved by sample exchange and comparison. Low percentage of mutant is the main reason which causes the discrepancy of BCR-ABL point mutation results among different laboratories.

[Clinical Efficacy of Dasatinib, Nilotinib and Imatinib in Newly Diagnosed Patients with Chronic-Phase Chronic Myeloid Leukemia: A Three-year Retrospective Analysis]

OBJECTIVE

To evaluate efficacy and safety of second-generation tyrosine kinase inhibitors (TKI) dasatinib, nilotinib and imatinib in treatment of newly diagnosed patients with chronic-phase chronic myeloid leukemia (CML).

METHODS

The clinical data and follow-up results of 163 patients with chronic-phase chronic myeloid lenkemia(CP-CML) who were treated in our hospital during the nearly 3 years were analysed retrospectively, among 163 patients 47 received dasatinib, 43 received nilotinib and 73 received imatinib. The efficacy, disease progression and safety were evaluated.

RESULTS

After treatment for 3 months, the rate of complete hematologic response(CHR) in three treatment groups were 77%, 79% and 67%, respectivily, CHR at 12 months in three treatment groups were 92%, 91% and 90%, respectively. By 3 months, the rates of complete cytogenetic response(CCyR) with dasatinib and nilotinib were higher than that with imatinib (55%, 53% vs 33%)(P<0.05 for both comparisons), CCyR at 12 months in three treatment groups were 86%, 88% vs 69% (P<0.05 for both comparisons). The rates of major molecular response(MMR) for dasatinib (11%) and nilotinib (9%) by 3 months were significantly higher than that for imatinib (1%) (P<0.05 for both comparisons), MMR at 12 months in three treatment groups were 49%, 50% and 28%, respectively (P<0.05 for both comparison). Progression to the accelerated or blast phase of CML occurred in 2 (4%) patients received dasatinib, 2 (5%) received nilotinib and 6 (8%) received imatinib. The safety profiles of these 3 second-generation TKI treatments were similar.

CONCLUSION

Both dasatinib and nilotinib induced strikingly higher and faster rates of complete cytogenetic response and major molecular response, with a statistically significant difference from imatinib.

Biomarkers for personalized oncology: recent advances and future challenges

Cancer is a group of diseases characterized by the uncontrolled growth and spread of abnormal cells and oncology is a branch of medicine that deals with tumors. The last decade has seen significant advances in the development of biomarkers in oncology that play a critical role in understanding molecular and cellular mechanisms which drive tumor initiation, maintenance and progression. Clinical molecular diagnostics and biomarker discoveries in oncology are advancing rapidly as we begin to understand the complex mechanisms that transform a normal cell into an abnormal one. These discoveries have fueled the development of novel drug targets and new treatment strategies. The standard of care for patients with advanced-stage cancers has shifted away from an empirical treatment strategy based on the clinical-pathological profile to one where a biomarker driven treatment algorithm based on the molecular profile of the tumor is used. Recent advances in multiplex genotyping technologies and high-throughput genomic profiling by next-generation sequencing make possible the rapid and comprehensive analysis of the cancer genome of individual patients even from very little tumor biopsy material. Predictive (diagnostic) biomarkers are helpful in matching targeted therapies with patients and in preventing toxicity of standard (systemic) therapies. Prognostic biomarkers identify somatic germ line mutations, changes in DNA methylation, elevated levels of microRNA (miRNA) and circulating tumor cells (CTC) in blood. Predictive biomarkers using molecular diagnostics are currently in use in clinical practice of personalized oncotherapy for the treatment of five diseases: chronic myeloid leukemia, colon, breast, lung cancer and melanoma and these biomarkers are being used successfully to evaluate benefits that can be achieved through targeted therapy. Examples of these molecularly targeted biomarker therapies are: tyrosine kinase inhibitors in chronic myeloid leukemia and gastrointestinal tumors; anaplastic lymphoma kinase (ALK) inhibitors in lung cancer with EML4-ALk fusion; HER2/neu blockage in HER2/neu-positive breast cancer; and epidermal growth factor receptors (EGFR) inhibition in EGFR-mutated lung cancer. This review presents the current state of our knowledge of biomarkers in five selected cancers: chronic myeloid leukemia, colorectal cancer, breast cancer, non-small cell lung cancer and melanoma.

[Allo-geneic hematopoietic stem cell transplantation in treatment with T315I mutation of chronic myelogenous leukemia]

OBJECTIVE

To explore the therapeutic efficacy of allo-geneic hematopoietic stem cell transplantation (allo-HSCT) for chronic myelogenous leukemia (CML) patients with T315I mutation.

METHODS

Retrospective analyses were conducted for 4 patients with T315I mutation of CML undergoing allo-HSCT from June 2012 to January 2014, including 2 cases in acceleration phase and 2 in chronic phase. There were 2 males and 2 females with ages from 26 to 45 years. Two patients received HLA-matched sibling allo-geneic peripheral blood stem cell transplantation (allo-PBSCT) while another 2 unrelated cord blood stem cell transplantation (UCBT). No splenomegaly was found before transplantation. One case had F317L mutation. All of them were treated with imatinib before transplantation. And the time from medication to T315I mutation was 20-35 months. All of them were conditioned with myeloablative regimen and received a combination of cyclosporine A (CsA) and mycophenolate mofetil (MMF) for preventing graft-versus-host disease (GVHD).

RESULTS

Myeloid implantation was achieved in all of them. The time of absolute neutrophil count (ANC) ≥ 0.5×10(9)/L were 10-28 days. One patient whose platelet was not implanted died from severe pulmonary infection at Day 88 post-transplantation. For 3 patients, platelet ≥ 20×10(9)/L were 15-33 days. But the marrow short tandem repeat (STR)-PCR was 100% donor type at the time of 30 days post-transplantation in all patients. One case of UCBT developed pre-implantation immune response syndrome (PES) and one acute GVHD of gradeI at Day 12 after allo-PBSCT. However both were controlled after treatment with methylprednisolone. And 1/3 evaluatable patients developed chronic GVHD. BCR/ABL transcript was detected by qualitative PCR after transplantation. And all BCR/ABL fusion genes turned negative after 30 days of transplantation. Up to the follow-up endpoint, there was no relapse except for one mortality. And the time of disease-free survival was 133, 248 and 704 days respectively.

CONCLUSIONS

Allo-HSCT is currently the optimal treatment for T315I mutation of CML. And umbilical cord blood is an ideal donor for those patients without HLA-matched sibling donor.

[Increased risk of severe acute graft-versus-host disease in low body mass index patients undergoing haploidentical allogeneic stem cell transplantation]

OBJECTIVE

To investigate the impact of body mass index (BMI) before transplantation on clinical outcomes of haploidentical allogeneic stem cell transplantation (allo-HSCT).

METHODS

We performed a retrospective cohort study of 253 adult patients with acute or chronic leukemia who received haploidentical allo-HSCT from August 2008 to September 2011. All conditioning regimens were myeloablative and bulsufan based. Patients were stratified according to BMI values (low BMI group: <18 kg/m(2); normal BMI group: ≥ 18 and < 25 kg/m(2); overweight BMI group: ≥ 25 kg/m(2)). Other possible risk factors correlated with GVHD, relapse, transplant related mortality (TRM) and overall survival (OS) included age and gender of donor and recipient, HLA disparity, relationship between donor and recipient, diagnosis, status of disease, ATG dose in conditioning regime(10 mg/kg , 6 mg/kg), mononuclear cells (MNC), CD(+)34 and CD(+)3 cell amount from granulocyte colony-stimulating factor (G-CSF) primed bone marrow grafts (G-BM) and G-CSF mobilized peripheral blood grafts(G-PB). Cox regression analysis was used to determine the related risk factors.

RESULTS

The median age of all 253 patients was 31 (18-56) years, including 128 cases with acute myeloid leukemia (AML), 95 cases with acute lymphocytic leukemia (ALL), and 30 cases with chronic myeloid leukemia (CML). According to primary diseases, 185 patients were classified in the standard -risk group and 68 cases in the high-risk group. Median follow-up time was 929 days (range: 48-1762 days) post-transplantation. Engraftment has been attained 252 (99.6%) recipients with the median time of granulocyte and platelet recovery 12 days (ranging from 9 to 45 days) and 16 days (ranging from 7 to 180 days), respectively. Cumulative incidences of acute GVHD was 33.2% with median time of 25 days (range: 13-88 days) after transplant. Multivariate analysis identified that low BMI was associated with an increased risk of grade III-IV acute GVHD (HR = 5.736, 95%CI 1.779-18.491, P = 0.003). There was no significant impact of BMI to other manifestations of GVHD, TRM, relapse or OS in different groups.

CONCLUSIONS

Our findings demonstrate a correlation between pre transplant BMI and clinical outcome post-transplant. Low BMI was associated with increased risk of severe acute GVHD in leukemia patients receiving haploidentical allo-HSCT. Meticulous supportive care pre-transplantation is required for low BMI patients.

[Advances in the target therapy of hematological malignancies]

With the rapid development of modern bio-medical technology, the pathogenesis of hematological malignancies including leukemia, lymphoma, myeloma has been illustrated with more and more attractive details. The diagnosis of hematological malignancies now becomes more precisely and clarified based on the progress than ever before, and the treatments of hematological malignancies keep the evolution in the way of integrating the novel molecular target drugs with conventional chemotherapy, radiotherapy, hematopoietic stem cell transplantation. The pivotal progress in the target therapy of hematological malignancies includes tyrosine kinase inhibitors for the treatment of chronic myeloid leukemia, CD20 monoclonal antibody treatment of B-cell lymphoma and CD20 positive leukemia, FLT3 inhibitors fo the treatment of FLT3 mutation positive high-risk acute myelogenous leukemia. The topics of this issue focus on the advances in this field, which reflects the new achievements in the research of hematological malignancies, and the trends of precise and stratified diagnosis as well as tailored target therapy in the future.

Functional characterization of a novel FGFR1OP-RET rearrangement in hematopoietic malignancies

The RET (REarranged during Transfection) receptor tyrosine kinase is targeted by oncogenic rearrangements in thyroid and lung adenocarcinoma. Recently, a RET (exon 12) rearrangement with FGFR1OP [fibroblast growth factor receptor 1 (FGFR1) oncogene partner] (exon 12) was identified in one chronic myelomonocytic leukemia (CMML) patient. We report the molecular cloning and functional characterization of a novel FGFR1OP (exon 11)-RET (exon 11) gene fusion event (named FGFR1OP-RET), mediated by a reciprocal translocation t(6; 10)(q27; q11), in a patient affected by primary myelofibrosis (PMF) with secondary acute myeloid leukemia (AML). The FGFR1OP-RET fusion protein displayed constitutive tyrosine kinase and transforming activity in NIH3T3 fibroblasts, and induced IL3-independent growth and activation of PI3K/STAT signaling in hematopoietic Ba/F3 cells. FGFR1OP-RET supported cytokine-independent growth, protection from stress and enhanced self-renewal of primary murine hematopoietic progenitor and stem cells in vitro. In vivo, FGFR1OP-RET caused a spectrum of disease phenotypes, with >50% of mice showing a fatal myeloproliferative disorder (MPD). Other phenotypes were leukemia transplantable in secondary recipients, dramatic expansion of the mast cell lineage, and reduction of repopulating activity upon lethal irradiation. In conclusion, FGFR1OP-RET chimeric oncogenes are endowed with leukemogenic potential and associated to myeloid neoplasms (CMML and PMF/AML).

Pentamidine sensitizes chronic myelogenous leukemia K562 cells to TRAIL-induced apoptosis

Pentamidine (PMD) is an anti-protozoa drug with potential anticancer activity. Here we show that PMD at clinically achievable plasma drug concentrations slightly inhibited the growth of human leukemia cell lines. PMD close to its therapeutic doses sensitized TRAIL-resistant K562 cells to the cytokine and potentiated TRAIL-induced apoptosis through activation of caspase-8 and -3. When we investigated the underlying mechanism, we observed that treatment with PMD increased DR5 expression at both mRNA and protein levels and down-regulated anti-apoptotic XIAP and Mcl-1 protein levels. This study provides a rationale for a more in-depth exploration into the combined treatment with PMD and TRAIL as a valuable strategy for leukemia therapy.

Sulforaphane potentiates the efficacy of imatinib against chronic leukemia cancer stem cells through enhanced abrogation of Wnt/β-catenin function

Sulforaphane (SFN) has been indicated for the prevention and suppression of tumorigenesis in solid tumors. Herein, we evaluated SFN's effects on imatinib (IM)-resistant leukemia stem cells (LSCs). CD34(+)/CD38(-) and CD34(+)/CD38(+) LSCs were isolated from KU812 cell line flowcytometrically. Isolated LSCs showed high expression of Oct4, CD133, β-catenin, and Sox2 and IM resistance. Differentially, CD34(+)/CD38(-) LSCs demonstrated higher BCR-ABL and β-catenin expression and imatinib (IM) resistance than CD34(+)/CD38(+) counterparts. IM and SFN combined treatment sensitized CD34(+)/CD38(-) LSCs and induced apoptosis, shown by increased caspase 3, PARP, and Bax while decreased Bcl-2 expression. Additionally, the combined treatment reduced BCR-ABL and β-catenin and MDR-1 protein expression. Mechanistically, IM and SFN combined treatment resensitized LSCs by inducing intracellular reactive oxygen species (ROS). Importantly, β-catenin-silenced LSCs exhibited reduced glutathione S-transferase pi 1 (GSTP1) expression and intracellular GSH level, which led to increased sensitivity toward IM and SFN. We demonstrated that IM and SFN combined treatment effectively eliminated CD34(+)/CD38(-) LSCs. Since SFN has been shown well tolerated in both animals and human, this regimen could be considered for clinical trials.

β-catenin inhibition synergizes with imatinib to delay CML recurrence

Genetic and pharmacologic inhibition of β-catenin blocks CML stem cell self-renewal.

[Establishment and identification of CML model via injection of K562 cells into the murine caudal vein]

This study was purposed to establish and identify the model of extramedullary infiltration of CML-NOD/SCID mice. 24 mice were irradiated with 270 cGy of (137)Cs and absorbed dose rate 80 cGy/min, and were randomly divided into test group I, test group II and control group. The mice in test group I and test group II were injected with 5×10(6) and 1×10(7) K562 cells per mouse respectively, the mice in control group were injected with 0.2 ml of normal saline. The general situation and survival time of these mice were monitored, the extramedullary infiltration of leukemia cells was detected by histopathology examination and RT-PCR. The results indicated that at 4 - 8 weeks after injection, all the mice of group I and group II displayed extramedullary infiltration, suggesting that CML/NOD-SCID model was successfully established. It is concluded that the model of extramedullary infiltration of CML/NOD-SCID mice can be established by injection K562 cells into caudal vein, and can be confirmed by histopathologic examination and detection of BCR-ABL fusion gene using RT-PCR.

[Preliminary establishment of transplanted human chronic myeloid leukemia model in nude mice]

Chronic myeloid leukemia (CML) is a malignant clonal disease derived from hematopoietic stem cells. CML stem cells were thought to be the root which could lead disease development and ultimately rapid change. However, a stable animal model for studying the characteristics of CML stem cells is currently lacking. This study was aimed to establish a transplanted human CML nude-mice model to further explore the biological behavior of CML stem cells in vivo, and to enrich CML stem cells in nude mice by series transplantation. The 4 - 6 weeks old BALB/c nude mice pretreated by splenectomy (S), cytoxan intraperitoneal injection (C) and sublethal irradiation (I) were transplanted intravenously with (5 - 7) × 10(7) of bone marrow mononuclear cells from CML patients in chronic phase. Alternatively, 4 - 6 weeks old BALB/c nude mice pretreated by lethal irradiation were transplanted intravenously with 5 × 10(6) homologous bone marrow cells of BALB/c nude mice together with (5 - 7) × 10(7) of bone marrow mononuclear cells from CML patients in chronic phase simultaneously. The leukemic cells engrafted and infiltrated in organs and bone marrow of the mice were tracked by reverse transcription-polymerase chain reaction (RT-PCR), plastic-embedded biopsy and flow cytometry. The results of these two methods were compared. The results showed that human CML cells engrafted and infiltrating into the bone marrow of two nude mice pretreated with SCI could be detected. In spite of the low successful rate, results suggested the feasibility of this method by using BALB/c nude mice as a human CML animal model. In contrast, in nude mice pretreated by the lethal dose irradiation, CML cells in the bone marrow could not be found. It is concluded that human bone marrow CML cells can results in leukemia in nude mice pretreated by SCI. Thus this study provides a new strategy for establishment of CML animal models which deserves further elaboration.