Peptides derived from the whole sequence of BCR-ABL bind to several class I molecules allowing specific induction of human cytotoxic T lymphocytes

Chronic myeloid leukemia (CML) is characterized cytogenetically by a t(9;22) translocation which generates a hybrid bcr-abl gene, encoding a p210^bcr-abl fusion protein. The induction in vitro of leukemia-specific T cells reactive with p210^bcr-abl is a strategy developed for an immunological therapeutic approach in CML. Peptides from the junction region of this chimeric protein have been considered as potential targets for a cytotoxic response against leukemic cells. However, only a few peptides encompassing the two p210^bcr-abl breakpoints have been shown to bind to the most common HLA class I molecules, which limits the number of patients who could benefit from this approach. We assume that the presence of chimeric BCR-ABL protein in leukemic cells may affect processing and delivery of peptides, possibly giving rise to new epitopes at the cell surface. We selected 162 peptides from the whole sequence of this protein, including 14 peptides of the b2a2 and b3a2 junctions, which had an anchor motif for a common HLA class I molecule. We tested their ability to bind to eight HLA class I molecules (HLA-A1, -A2, -A3, -A11, -B7, -B8, -B27, -B44). We identified 48 peptides from outside the junction region, with intermediate or strong binding capacities to these HLA class I molecules contrasting with only six junction peptides with a moderate binding capacity to HLA-A3/A11, -B8, or -B44 molecules. Moreover, cytotoxic T lymphocyte lines specific for various peptides outside the junction were generated from peripheral blood mononuclear cells of HLA-A2 or -B7 healthy donors and from one CML patient. These results contribute to evaluation of immunity to the BCR-ABL chimeric protein. Further studies are required to investigate whether such epitopes are correctly processed and presented by leukemic cells.     

Expression of CD25 is a specific and relatively sensitive marker for the Philadelphia chromosome (BCR-ABL1) translocation in pediatric B acute lymphoblastic leukemia

Background: Precursor B acute lymphoblastic leukemia (B-ALL) is the most common cancer in children and overall, has an excellent prognosis. However, the Philadelphia chromosome translocation (Ph+), t(9;22)(q34;q11), is present in a small subset of patients and confers poor outcomes. CD25 (IL-2 receptor alpha chain) expression has been associated with Ph+ B-ALL in adults, but no similar study has been performed in pediatric B-ALL. Methods: A retrospective analysis of 221 consecutive pediatric patients with a diagnosis of B-ALL (blood and/or bone marrow) from 2009 to 2012 was performed to determine an association between Ph+ B-ALL and CD25 expression. A threshold of 25% was used to define positive cases for CD25 expression by flow cytometry. Results: There were 221 patients with a diagnosis of B-ALL ranging from 2 to 22 years (median, 6 years). Eight (3.6%) B-ALL patients were positive for the Philadelphia chromosome translocation (Ph+ B-ALL) and 213 were negative (Ph-negative B-ALL). CD25 expression was observed in 6 of 8 (75%) Ph+ B-ALL patients and 6 of 213 (2.8%) Ph-negative B-ALL patients. CD25 expression was significantly higher in Ph+ B-ALL compared to Ph-negative B-ALL, with median CD25 expression of 64% (range 0-93%) and 0.1% (range 0-91%), respectively (P ≤ 0.0002). Therefore, CD25 expression as a predictor of Ph+ B-ALL had 75% sensitivity, 97% specificity, 50% positive predictive value and 99% negative predictive value. Conclusions: CD25 expression is a specific and relatively sensitive marker for the identification of Ph+ B-ALL in the pediatric population.     

γ-Catenin-Dependent Signals Maintain BCR-ABL1+ B Cell Acute Lymphoblastic Leukemia

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The role of E255K/V-inclusive mutations in a Philadelphia-positive acute lymphoblastic leukemia with mutation evolution during sequential TKIs therapies: A case report

Rationale:Until recently, the survival rate in patients with Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL) was approximately 30%. Tyrosine kinase inhibitors (TKIs), which are a new class of drugs that target BCR-ABL fusion protein, have shown to be effective in treating Ph+ ALL in adults. However, the resistance mechanisms that promote the disease recurrence have altered the initial success of these revolutionary agents.Patient concerns:A 71-year-old Chinese female patient who suffered from severe shoulder and back pain for 1 week.Diagnosis:The patient was diagnosed with Ph+ ALL (B–cell) because of the following items. Complete blood count showed extremely abnormal white blood cell count (26.26×10⁹/l), hemoglobin concentration (65 g/l) and platelet count (14×10⁹/l). And because that Bone marrow aspirate showed 72.5% lymphoblasts and 59.30% lymphoblasts were confirmed by flow cytometry (FCM). At mean time, Real-time fluorescent quantitative PCR analysis confirmed that the P190 BCR/ABL fusion gene expression was 5.9%. Karyotype analysis indicated the following: 45, XX, −7, t (922) (q34; q11) [cp3].Interventions:The patient was treated with chemotherapy and different TKIs including imatinib, dasatinib, ponatinib, and bosutinib.Outcomes:The patient achieved complete remissions with different TKIs after diagnose but relapsed afterward and died of infection.Lessons:Multidrug-resistant mutations within the BCR-ABL1 kinase domain are an emerging clinical problem for patients receiving sequential TKIs therapy. Acquisition of E255K/V-inclusive mutations is usually associated with ponatinib resistance, thus it is necessary to screen out new real pan-inhibitor compounds for all BCR/ABL mutations and figure out the potential efficacy of asciminib-based drug combinations in the future.     

外周血样本的存储和运输对BCR-ABL（P210）转录本水平定量检测结果的影响

目的探索慢性髓性白血病（CML）患者外周血样本的存储和运输对实时定量PCR（RQ-PCR）检测BCR-ABL（P210）转录本水平的影响。方法采集84例CML患者外周血样本，根据储存时间（0、6、12、24、48和72 h）、温度［室温（18～24 °C）和低温（2～8 °C）］以及振荡条件（振荡时长3、6和12 h）设置不同分组，RQ-PCR法检测不同条件下外周血样本BCR-ABL（P210）转录本水平。本研究将BCR-ABL拷贝数、ABL拷贝数和BCR-ABL（P210）转录本水平等原始数据进行对数转化（log₁₀^N）。结果①琼脂糖凝胶电泳结果显示：室温条件下，储存48、72 h的样本RNA出现显著降解；②储存温度方面，总体样本中，室温储存48、72 h的样本BCR-ABL拷贝数检测水平显著低于低温储存的样本（P<0.05）；然而BCR-ABL（P210）转录本水平在低温储存与室温储存条件下检测结果差异无统计学意义（P>0.05）；③储存时间方面，与基线的3.35±1.60相比，总体样本的BCR-ABL拷贝数检测结果仅在室温储存储存下48 h（2.93±1.59）和72 h（2.79±1.42）显著下降（P<0.05）；与基线的5.47±0.35相比，总体样本中ABL拷贝数检测结果在48 h（低温5.29±0.30，室温5.06±0.38）和72 h（低温5.11±0.54，室温4.64±0.79）均显著下降（P<0.05）。但是，与基线的−0.56±1.51相比，无论低温或室温条件下，不同储存时间（6、12、24、48和72 h）的样本BCR-ABL（P210）转录本水平检测结果无显著改变（P>0.05）；④振荡方面，与基线的−0.60±1.37相比，振荡3、6、12 h的样本BCR-ABL（P210）转录本水平检测结果无显著改变（P>0.05）。结论样本储存时间、储存温度及运输振荡因素可以影响BCR-ABL、ABL拷贝数的检测结果，但对BCR-ABL（P210）转录本水平定量检测结果无显著影响。     

Synthesis of imatinib,a tyrosine kinase inhibitor,labeled with carbon-14

Imatinib (Gleevec) is a multiple tyrosine kinase inhibitor that decreases the activity of the fusion oncogene called BCR-ABL (breakpoint cluster region protein-Abelson murine leukemia viral oncogene homolog) and is clinically used for the treatment of chronic myelogenous leukemia and acute lymphocytic leukemia. Small molecule drugs, such as imatinib, can bind to several cellular proteins including the target proteins in the cells, inducing undesirable effects along with the effects against the disease. In this study, we report the synthetic optimization for ¹⁴C-labeling and radiosynthesis of [¹⁴C]imatinib to analyze binding with cellular proteins using accelerator mass spectroscopy. ¹⁴C-labeling of imatinib was performed by the synthesis of ¹⁴C-labeld 2-aminopyrimidine intermediate using [¹⁴C]guanidine·HCl, which includes an in situ reduction of an inseparable byproduct for easy purification by HPLC, followed by a cross-coupling reaction with aryl bromide precursor. The radiosynthesis of [¹⁴C]imatinib (specific activity, 631 MBq/mmol; radiochemical purity, 99.6%) was achieved in six steps with a total chemical yield of 29.2%.