Study On The Clinical And Pathogenic Mechanisms Of Childhood Malignant Tumors

Objectives: To evaluate the value of next generation sequencing(NGS)in detection of BCR-ABL1 fusion gene and disease-related genetic variation in pediatric leukemia;To investigate the long-term efficacy and the prognostic factors in pediatric hepatoblastoma(HB)and relasped Wilms tumor(WT)according to the standard diagnostic and therapeutic regimen.Methods: In the first part,genome DNA were extracted from bone marrow samples or cryopreserved cells of newly diagnosed BCR-ABL1 positive pediatric leukemia patients by quantitative polymerase chain reaction(Q-PCR)or fluorescence in situ hybridization(FISH)from January 2007 to December 2016 at Shanghai Children’s Medical Center.Fusion gene and tumor-related genes were sequenced using targeted capture next-generation sequencing technology and analyzed by bioinformatics.The positive fusion and mutation gene were resequenced using the Sanger method.In the second part,collecting HB cases from June 2000 to June 2015 and recurrent WT cases from April 2006 to June 2016 admitted to Shanghai Children’s Medical Center.Retrospective analysis was performed in clinical features,long-term outcomes and prognostic factors.Log-rank test was used for univariate analysis.Results:1.A total of 120 cases of BCR-ABL1 positive leukemia were collected,including 60 cases of chronic myeloid leukemia(CML),54 cases of acute lymphoblastic leukemia(ALL),4 cases of mixed leukemia,2 cases of acute myeloid leukemia Cell leukemia(AML).The positive rate of BCR-ABL1 fusion gene by targeting NGS was 87.5%(105/120),of which 68 were M-bcr,37 were m-bcr.The most common tumor-related gene mutation was ABL1(9/120,7.5%).A total of 11 ABL1 mutations were detected and 10 were in ABL1 kinase domain.2.A total of 74 cases(45 males and 29 females)were included in this study.The median age at diagnosis was 1.7 years.The median follow-up time was 39.6 months(range 4.1-135.3).59 cases got complete remission and 9 cases died until the last follow-up.The estimated 5 years overall survival(OS)and event free survival(EFS)rate were 83.4% and 77.2%.In univariate analysis,the 5 years EFS in low risk group and high risk group were 100% and 71.1%(P = 0.03),respectively.Whether AFP back to normal after 3 cycles of postoperative chemotherapy,the five years OS were 88.4% and 75%(P = 0.024).The platelet count,lactate dehydrogenase and ferrtin level of high risk group patients were higher then those of low risk.3.A total of 15 cases(5 males and 10 females)were enrolled in this study.The median age at diagnosis was 3.8 years.The tumor staging at diagnosis included 1 case of stageⅠ,7 cases of stageⅡand 7 cases of stage Ⅲ.The median follow-up time was 34.6 months(range 12.5-132.7).The time from initial diagnosis to relapse was 7.9 months(range 3.1-17.9).4 cases experienced local recurrence,9 cases relapsed with metastases and 2 cases relapsed both in local site and with metastases.Until the last follow-up,8 cases achieved continuous CR,3 cases relapsed again or in progressing and 4 cases died.The estimated 5 years OS and EFS rate were 70% and 52%.According to whether received ABMT(5 cases)or not,the 5 years EFS rate were 51% and 53%.According to whether relapsed within 6 months after diagnosis or not,the 5 years EFS rate were 38% and 56% respectively.Conclusions: 1.Targeted capture NGS technique provides a comprehensive overview of the BCR-ABL1 fusion and gene mutation information.ABL1 is the most common disease-associated mutation gene.2.The prognosis of HB is reasonable and comparable.AFP after 3 cycles of postoperative chemo recover or not is a prognostic factor.3.The long survival rate of pediatric relapsed FH WT have reached 50% in our experience.However,the efficiency of ABMT is uncertain.