[Establishment of leukemia cell model with inducible AML1-ETO expression and its effect on fatty acid metabolism in leukemia cells]

Objective: To investigate the effect of the AML1-ETO (AE) fusion gene on the biological function of U937 leukemia cells by establishing a leukemia cell model that induces AE fusion gene expression. Methods: The doxycycline (Dox) -dependent expression of the AE fusion gene in the U937 cell line (U937-AE) were established using a lentivirus vector system. The Cell Counting Kit 8 methods, including the PI and sidanilide induction, were used to detect cell proliferation, cell cycle-induced differentiation assays, respectively. The effect of the AE fusion gene on the biological function of U937-AE cells was preliminarily explored using transcriptome sequencing and metabonomic sequencing. Results: ①The Dox-dependent Tet-on regulatory system was successfully constructed to regulate the stable AE fusion gene expression in U937-AE cells. ②Cell proliferation slowed down and the cell proliferation rate with AE expression (3.47±0.07) was lower than AE non-expression (3.86 ± 0.05) after inducing the AE fusion gene expression for 24 h (P<0.05). The proportion of cells in the G(0)/G(1) phase in the cell cycle increased, with AE expression [ (63.45±3.10) %) ] was higher than AE non-expression [ (41.36± 9.56) %] (P<0.05). The proportion of cells expressing CD13 and CD14 decreased with the expression of AE. The AE negative group is significantly higher than the AE positive group (P<0.05). ③The enrichment analysis of the transcriptome sequencing gene set revealed significantly enriched quiescence, nuclear factor kappa-light-chain-enhancer of activated B cells, interferon-α/γ, and other inflammatory response and immune regulation signals after AE expression. ④Disorder of fatty acid metabolism of U937-AE cells occurred under the influence of AE. The concentration of the medium and short-chain fatty acid acylcarnitine metabolites decreased in cells with AE expressing, propionyl L-carnitine, wherein those with AE expression (0.46±0.13) were lower than those with AE non-expression (1.00±0.27) (P<0.05). The metabolite concentration of some long-chain fatty acid acylcarnitine increased in cells with AE expressing tetradecanoyl carnitine, wherein those with AE expression (1.26±0.01) were higher than those with AE non-expression (1.00±0.05) (P<0.05) . Conclusion: This study successfully established a leukemia cell model that can induce AE expression. The AE expression blocked the cell cycle and inhibited cell differentiation. The gene sets related to the inflammatory reactions was significantly enriched in U937-AE cells that express AE, and fatty acid metabolism was disordered.

[Preparation of a novel tri-specific T cell engager targeting CD19 antigen and its anti-leukemia effect exploration]

Objective: To prepare a novel tri-specific T cell engager (19TriTE) targeting CD19 antigen, and to investigate its immunotherapeutic effect on CD19-positive hematological malignancies. Methods: 19TriTE was constructed by molecular cloning technology and successfully expressed through the eukaryotic expressing system. The effects of 19TriTE on the proliferation and activation of T cells, as well as the specific cytotoxicity against CD19 positive tumor cell lines were verified. Results: ①19TriTE expressing plasmid was constructed and successfully expressed through the eukaryotic expressing system. ②19TriTE can specifically bind to T cells and Nalm6 cells, with equilibrium dissociation constants of 19.21 nmol/L and 11.67 nmol/L, respectively. ③The expression rates of CD69 positive T cells and CD25 positive T cells were 35.4% and 49.8% respectively, when 2 nmol/L 19TriTE were added in the co-culture system, which were significantly higher than those in the control group. ④19TriTE can significantly promote the proliferation of T cells. The absolute count of T cells expanded from the initial one million to 74 million with an 74 fold increase at the concentration of 1 nmol/L on day 12. ⑤19TriTE can significantly mediate T cells killing of CD19 positive target cells in a dose-dependent manner. At the concentration of 10 nmol/L, the target cells lysis reached 50%. ⑥Degranulation experiment verified that 19TriTE can activate T cells in the presence of CD19 positive target cells, and the activation of T cells positively correlated with the dose of 19TriTE. ⑦When 19TriTE fusion protein co-cultured with T cells and target cells overexpression RFP and luciferase genes respectively, 19TriTE can notably mediate T cells killing of CD19 positive target cells through fluorescent microscope or bioluminescence imaging technology. Conclusion: In this study, we successfully constructed and expressed 19TriTE fusion protein and verified that it can effectively activate T cells and promote their proliferation in vitro. At the same time, it can bind to CD19 positive target cells and T cells, as well as enhance T cells anti-leukemia effect in vitro, providing the foundation for further clinical research.

[CD19 antigen loss after treatment of Bispecific T-cell Engager and effective response to salvage bispecific CAR-T therapy in B cell acute lymphoblastic leukemia: a case report and literature review]

Objective: To analyze the influence of CD19 isoforms to the efficacy of CD19/CD3 Bispecific T-cell Engager (BiTE) antibody, and explore the resistance mechanism of BiTE immunotherapy. Methods: Semi-quantitative RT-PCR (qRT-PCR) was used to detect the expression of CD19 mRNA isoforms before and after BiTE treatment in a patient with CD19(+) B cell acute lymphoblastic leukemia (ALL) . CD19 isoforms were analyzed by Sanger sequencing. Flow cytometry and transcriptome sequencing were performed to analyze the expression of cell lineage specific molecules before and after BiTE treatment. Results: The expression of CD19 isoform with exon 2 deletion was identified at diagnosis. After relapsed and treatment of BiTE antibody, the patient did not achieve remission and CD19 antigen on leukemic cells turned negative detected by flow cytometry after BiTE treatment. However the expression ratio of CD19 isoform with exon 2 deletion was not increased. Flow cytometry phenotype and transcriptome sequencing confirmed that no linage switching developed, which suggested the expression of CD19 isoform caused by exon alternative splicing and lineage switching was not related to CD19 epitope loss in this patient. This patient achieved complete remission by sequential administration of self-developed CD22 CAR-T and CD19 CAR-T after disease progression. Conclusion: Targeting or combining an alternative antigen specific CAR-T may be a promising treatment option after losing CD19 expression in relapsed ALL.

[Construction of a new anti-CD123 chimeric antigen receptor T cells and effect of anti-acute myeloid leukemia]

目的

构建一种新的靶向CD123的嵌合抗原受体T细胞(CAR-T细胞)，为CD123阳性白血病的免疫治疗提供实验参考。

方法

通过单克隆筛选技术获得能稳定分泌CD123抗体的杂交瘤细胞株6E11，将杂交瘤细胞扩增后腹腔注射至Balb/c小鼠腹腔内，收集腹水并处理、纯化得到单克隆抗体，测定抗体效价并对其特异性进行验证；RT-PCR法获得轻链和重链可变区序列，并以此为基础利用分子克隆技术构建一种新的靶向CD123嵌合抗原受体，包装病毒后感染T细胞制备CD123CAR-T细胞，通过功能实验初步探讨6E11CAR-T细胞体外抗白血病的能力。

结果

①获得1株稳定分泌抗人CD123抗体的杂交瘤细胞株6E11并获得其可变区序列。②6E11单克隆抗体对CD123蛋白亲和性高，解离常数(K_d值)为2.10nmol/L，特异性识别CD123阳性细胞且与CD123阴性细胞无交叉反应。 ③成功构建了CD123CAR慢病毒载体，感染T细胞后获得了靶向CD123的CAR-T细胞(6E11CAR-T)，感染效率大于60％。 ④6E11CAR-T能明显杀伤CD123阳性靶细胞MV4-11，效靶比1∶1时6E11CAR-T细胞对MV4-11细胞的杀伤比例明显高于 Vecor-T细胞[(98.60±1.20)％对(20.28±6.74)％，P<0.001]，但对CD123阴性靶细胞K562没有明显杀伤作用。 ⑤MV4-11细胞可以显著激活6E11CAR-T，但对Vecor-T细胞无明显激活作用[(26.33±3.30)％对(1.17±0.06)％，P<0.001]。⑥6E11CAR-T与MV4-11细胞共培养上清中细胞因子水平均显著高于Vecor-T组[IL-2：(92.90±1.51)pg/ml对(6.05±3.41)pg/ml，P<0.001；TNF-α：(1 407.20±91.95)pg/ml对(7.86±0.85)pg/ml，P<0.001；IFN-γ：(5 614.60±170.17)pg/ml对(8.42±2.70)pg/ml，P<0.001]但与 K562细胞共培养后，两组各细胞因子水平差异无统计学意义。 ⑦6E11CAR-T在与CD123阳性髓系白血病(AML)原代细胞共培养过程中被显著激活，且能有效杀伤原代 AML细胞。

结论

杂交瘤细胞株6E11能稳定分泌高效特异的抗人CD123单克隆抗体，可用于检测表达人CD123的细胞，也能应用在靶向人CD123蛋白的肿瘤免疫治疗中，以 6E11Ig可变区序列为抗原识别区的CD123CAR-T细胞，具有明确的体外抗白血病活性，为进一步的临床研究奠定了基础。

[Screening of adult Ph-like acute lymphoblastic leukemia by multiplex real-time quantitative PCR]

目的

探讨多重实时荧光定量PCR法早期、快速筛查Ph样急性淋巴细胞白血病（ALL）的可行性，了解Ph样ALL的临床特征及预后。

方法

2010年10月至2016年3月收治的118例初诊成人B-ALL患者纳入研究，利用多重实时荧光定量PCR法检测其中58例BCR-ABL融合基因和MLL重排均阴性患者Ph样相关融合基因及细胞因子受体样因子2（CRLF2）表达情况。比较分析Ph样融合基因阳性和（或）CRLF2高表达患者的临床特征、疗效和预后。

结果

检出Ph样融合基因阳性患者9例（9/58，15.5%），CRLF2高表达患者10例（10/58，17.2%）。Ph样融合基因阳性和（或）CRLF2高表达组、Ph阳性组、MLL重排阳性组以及其他患者组在年龄、WBC、免疫分型、细胞遗传学、危险度分组方面差异有统计学意义（P值均<0.01）。四组患者的2年总生存率分别为65%、47%、64%、74%（P=0.043），2年无复发生存率分别为51%、39%、62%、70%（P=0.010）。

结论

采用多重实时荧光定量PCR法筛查Ph样ALL患者可行，Ph样ALL患者预后较差。

[Spectrum of somatic mutations and their prognostic significance in adult patients with B cell acute lymphoblastic leukemia]

Objective: To investigate the spectrum of gene mutations in adult patients with B-acute lymphoblastic leukemia (B-ALL), and to analyze the influences of different gene mutations on prognosis. Methods: DNA samples from 113 adult B-ALL patients who administered from June 2009 to September 2015 were collected. Target-specific next generation sequencing (NGS) approach was used to analyze the mutations of 112 genes (focused on the specific mutational hotspots) and all putative mutations were compared against multiple databases to calculate the frequency spectrum. The impact of gene mutation on the patients' overall survival (OS) and recurrence free survival (RFS) was analyzed by the putative mutations through Kaplan-Meier, and Cox regression methods. Results: Of the 113 patients, 103 (92.0%) harbored at least one mutation and 29 (25.6%) harbored more than 3 genes mutation. The five most frequently mutated genes in B-ALL are SF1, FAT1, MPL, PTPN11 and NRAS. Gene mutations are different between Ph+ B-ALL and Ph- B-ALL patients. Ph- B-ALL patients with JAK-STAT signal pathway related gene mutation, such as JAK1/JAK2 mutation showed a poor prognosis compared to the patients without mutation (OS: P=0.011, 0.001; RFS: P=0.014,<0.001). Patients with PTPN11 mutation showed better survival than those without mutation, but the difference was not statistically significant (P value > 0.05). Besides, in Ph+ B-ALL patients whose epigenetic modifications related signaling pathway genes were affected, they had a worse prognosis (OS: P=0.038; RFS: P=0.047). Conclusion: Gene mutations are common in adult ALL patients, a variety of signaling pathways are involved. The frequency and spectrum are varied in different types of B-ALL. JAK family gene mutation usually indicates poor prognosis. The co-occurrence of somatic mutations in adult B-ALL patients indicate the genetic complex and instability of adult B-ALL patients.