STAT5B Mutation In T-cell Acute Lymphoblastic Leukemia And Targeted Therapy

Objective:1.To analyze the clinical and biological characteristics of patients diagnosed with T-ALL at First Affiliated Hospital of Soochow University. 2.To study the frequency of STAT5 B N642H mutation in T-ALL and 8 kinds of T-ALL cell lines saved by our center. 3.To explain the mechanism of the STAT5 B mutation in T-ALL and to screen effective targeted drugs.Patients and Methods:1.Patients:A total of 141 adult patients(116 males/25 females)diagnosed with T-ALL at Jiangsu Institute of Hematology from January 2006 to July 2014 were retrospectively analyzed in the present study.There were 93 adult patients(>18 years old)and 28 pediatric patients(≤18 years old).The median age of cases was 24 years old. 2.A cohort of 93 T-ALL patients and 8 kinds of T-ALL cell lines were studied. Polymerase chain reaction(PCR) amplification and Sanger sequencing were applied for mutation screening. 3. Targeted drugs were screened on the cell line KOPT-K1 with STAT5 B N642H mutation by cell counting kit-8(CCK-8) assay. 4.Flow cytometry(FCM) was used to analyze the apoptosis and cell cycle of treated cells.Results:The Characteristics of Cytogenetics and Molecular Genetics in T cell Acute Lymphoblastic Leukemia1、141 newly diagnosed patients with T-ALL were registered in this study.The median of WBC was 93×109/L,the median of Hb was 105g/L,the median of PLT was 60×109/L, and the median percentage of bone marrow blast cells was 83.5%.According to the Franc h-American- British(FAB) classification, 40, 46 and 55 cases were diagnosed as ALL-L1, ALL-L2 and not otherwise specified(NOS)respectively. All their clinical and biologic characteristics were analyzed. the median percentage of bone marrow blast cells were significantly among the three groups(P<0.05). However,age,sex, median Hb levels and platelets(PLT) counts showed no significant difference among different groups. 2.Of 139 successfully karyotyped patients, abnormal karyotypes were found in 41.7% patients(58/139). The most common abnormality is monosomoal karyotype(8/139),next is t(11;14)(p13;q11)(7/139),recurring chromosoe abnormalities including: 6q-, del(6)(q21), i(7q),+8. 3.SIL-TAL1 and SET-NUP214 were detected in 8 cases and 4 cases, respectively. There were also other abnormalities such as SET-CAN, BCR-ABL, HOX11, MLL-MLL, MLL-AF10, MLL-AF9. 4.Of 117 cases,PHF6、FBXW7、NOTCH1、WT1、LMO2 gene mutation were detected.NOTCH1/PHF6 mutations were the most frequent abnormalities(47% and 13.7, respectively)STAT5 mutation in T cell Acute Lymphoblastic Leukemia and T-ALL cell lineIn this study, none of STAT5 B mutation was identified in 65 adult T-ALL patients, and only one STAT5 B N642H mutation was detected in 28 pediatric patients based on Sanger sequencing analysis. We also found that the STAT5 B N642H mutation occurred in KOPT-K1 cell line.Medicine screening and the mechanism of STAT5 B mutation1. To study 4 kinds of candidate drugs,TKI and AZD1480 inhibited the proliferation of KOPT-K1,especially the third generation of TKI Ponatinib. 2. After treated for 72 h,FCM analysis showed that the ratio of G0/G1 of KOPT-K1 cells treated by Ponatinib was higher than in control group(58.88±4.07% versus 75.61±0.12%, P <0.05).Conclusion:1.Of 141 de novo T-ALL patients, the detection rate of abnormal karyotype was 41.7%.In the study,the highest rates of moleculor abnormalities were SIL-TAL1 and NOTCH1 mutation. 2.Somatic mutation of STAT5 B N642H might have rare occurrence in adult T-cell acute lymphoblastic leukemia. And T-ALL cell line KOPT-K1 carries STAT5 B mutation. 3.The effect of growth inhibition of Ponatinib was stronger than that of AZD1480. Ponatinib may have a therapeutic potential in the small population of STAT5 B mutation patients.