Poor responses to tyrosine kinase inhibitors in a child with precursor B‐cell acute lymphoblastic leukemia with SNX2‐ABL1 chimeric transcript

In addition to BCR, various rare fusion partners for the ABL1 gene have been reported in leukemia. We have identified the fusion gene SNX2‐ABL1 in a pediatric case of acute lymphoblastic leukemia (ALL), which has only once previously been reported in an adult patient. Cytogenetic analysis detected this fusion gene arising from a t(5;9)(q22;q34) translocation. ALL cells carrying a SNX2‐ABL1 fusion exhibited a BCR‐ABL1+ ALL‐like gene expression profile. The patient poorly responded to dasatinib but partially responded to imatinib. Treatment using tyrosine kinase inhibitors requires further investigation to optimize the genotype‐based treatment stratification for patients with SNX2‐ABL1 fusion.     

Overcoming EMT-associated resistance to anti-cancer drugs via Src/FAK pathway inhibition

Epithelial to mesenchymal transition (EMT) is a key process in embryonic development and has been associated with cancer metastasis and drug resistance. For example, in EGFR mutated non-small cell lung cancers (NSCLC), EMT has been associated with acquired resistance to the EGFR inhibitor erlotinib. Moreover, “EGFR-addicted” cancer cell lines induced to undergo EMT become erlotinib-resistant in vitro. To identify potential therapeutic vulnerabilities specifically within these mesenchymal, erlotinib-resistant cells, we performed a small molecule screen of ~200 established anti-cancer agents using the EGFR mutant NSCLC HCC827 cell line and a corresponding mesenchymal derivative line. The mesenchymal cells were more resistant to most tested agents; however, a small number of agents showed selective growth inhibitory activity against the mesenchymal cells, with the most potent being the Abl/Src inhibitor, dasatinib. Analysis of the tyrosine phospho-proteome revealed several Src/FAK pathway kinases that were differentially phosphorylated in the mesenchymal cells, and RNAi depletion of the core Src/FAK pathway components in these mesenchymal cells caused apoptosis. These findings reveal a novel role for Src/FAK pathway kinases in drug resistance and identify dasatinib as a potential therapeutic for treatment of erlotinib resistance associated with EMT.     

A novel patient stratification strategy to enhance the therapeutic efficacy of dasatinib in glioblastoma

BackgroundGlioblastoma is the most common primary malignancy of the central nervous system with a dismal prognosis. Genomic signatures classify isocitrate dehydrogenase 1 (IDH)-wildtype glioblastoma into three subtypes: proneural, mesenchymal, and classical. Dasatinib, an inhibitor of proto-oncogene kinase Src (SRC), is one of many therapeutics which, despite promising preclinical results, have failed to improve overall survival in glioblastoma patients in clinical trials. We examined whether glioblastoma subtypes differ in their response to dasatinib and could hence be evaluated for patient enrichment strategies in clinical trials.MethodsWe carried out in silico analyses on glioblastoma gene expression (TCGA) and single-cell RNA-Seq data. In addition, in vitro experiments using glioblastoma stem-like cells (GSCs) derived from primary patient tumors were performed, with complementary gene expression profiling and immunohistochemistry analysis of tumor samples.ResultsPatients with the mesenchymal subtype of glioblastoma showed higher SRC pathway activation based on gene expression profiling. Accordingly, mesenchymal GSCs were more sensitive to SRC inhibition by dasatinib compared to proneural and classical GSCs. Notably, SRC phosphorylation status did not predict response to dasatinib treatment. Furthermore, serpin peptidase inhibitor clade H member 1 (SERPINH1), a collagen-related heat-shock protein associated with cancer progression, was shown to correlate with dasatinib response and with the mesenchymal subtype.ConclusionThis work highlights further molecular-based patient selection strategies in clinical trials and suggests the mesenchymal subtype as well as SERPINH1 to be associated with response to dasatinib. Our findings indicate that stratification based on gene expression subtyping should be considered in future dasatinib trials.     

酪氨酸激酶抑制剂达沙替尼抗黑色素瘤的体外研究

目的 探讨达沙替尼对小鼠黑色素瘤B16F10细胞株体外增殖、迁移和凋亡的影响.方法 采用MTT法检测不同浓度(3.125、6.250、12.500、25.000、50.000 μg/mL)达沙替尼在24、48 h对B16F10细胞增殖能力的影响;采用细胞划痕实验和Transwell体外迁移实验检测达沙替尼对B16F10细胞迁移能力的影响;DAPI染色法观察给药后细胞核形态的变化;流式细胞仪检测达沙替尼对B16F10细胞凋亡率和细胞周期的影响;荧光显微镜观察达沙替尼对B16F10细胞线粒体膜电位的影响,并用荧光分光光度计检测Caspase 3和Caspase 9的活化程度.结果 达沙替尼对B16F10细胞的增殖有抑制作用,并呈浓度和时间依赖性.细胞划痕实验及Transwell体外迁移实验结果表明:达沙替尼能够有效地抑制B16F10细胞的迁移.分别以低、中、高3个浓度(6.250、12.500、25.000 μg/mL)的达沙替尼作用于B16F10细胞24 h后,细胞形态发生明显改变,核裂解,形成多个凋亡小体,凋亡率分别为(34.06±0.83)％、(50.24±1.66)％和(88.91±0.96)％,与对照组比较差异均有统计学意义(P＜0.05).达沙替尼对B16F10细胞周期的影响较小,其中对G1期有微弱的阻滞作用.中浓度(12.500μg/mL)达沙替尼组能够引起B16F10细胞线粒体膜电位的降低,Caspase 3和Caspase 9活性的增加,表明达沙替尼可能是通过线粒体介导的Caspase通路引起细胞凋亡.结论 达沙替尼能有效地抑制小鼠黑色素瘤B16F10细胞株体外增殖与迁移,诱导细胞凋亡,有望成为一种有效的抗黑色素瘤药物.     

The role of Src in prostate cancer.

The Src family kinases (SFKs) are the largest family of nonreceptor protein tyrosine kinases and are responsible for signal transduction during many cellular activities, including differentiation, adhesion, and migration. Aberrant Src/SFK activity has been widely implicated in cancer development. Several lines of evidence indicate a role for SFKs in the development of prostate cancer, e.g. SFK overexpression in prostate cancer cell lines and tissues and reduced cancer cell proliferation, invasion, and migration following Src inhibition. In particular, Src may be involved in androgen-independent growth during advanced stages of disease. Src signaling is also a key pathway during normal and dysregulated bone functioning, and bone metastases are responsible for substantial morbidity in advanced prostate cancer. Src/SFK inhibition therefore represents a potentially useful therapeutic strategy for patients with various stages of prostate cancer. To date, four Src inhibitors have reached clinical trials. Of these, the broadest range of in vitro prostate cancer data are available for dasatinib, which inhibits several SFKs as well as other tyrosine kinases. Src inhibitors may be specifically evaluated in prostate cancer clinical trials in the near future.     

Treatment responses to cladribine and dasatinib in rapidly progressing aggressive mastocytosis

Background Systemic mastocytosis (SM) is a mast cell neoplasm in which neoplastic cells usually display the D816V‐mutated variant of KIT. Cladribine (2CdA) and dasatinib are two drugs that counteract the in vitro growth of neoplastic mast cells in SM. However, only little is known about the in vivo effects of these drugs in SM. Patient and methods We report on a patient with highly aggressive interferon‐alpha‐resistant SM who was treated with 2CdA and dasatinib. In vitro pretesting revealed a response of neoplastic mast cells to both compounds with reasonable IC₅₀ values. Results The patient was treated with six cycles of 2CdA (0·13 mg kg^?1 intravenously daily on 5 consecutive days). Despite a short‐lived major clinical response and a decrease in serum tryptase, the patient progressed to mast cell leukaemia after the sixth cycle of 2CdA. The patient then received two further courses of 2CdA followed by treatment with dasatinib (100 mg per os daily). However, no major response was obtained and the patient died from disease progression after 2 months. Conclusions In a patient with rapidly progressing aggressive SM, neither 2CdA nor dasatinib produced a long‐lasting response in vivo, despite encouraging in vitro results. For such patients, alternative treatment strategies have to be developed.