| OBJECTIVE Fusion genes have been identified in diagnostic stratification andprognostic assessment, minimal residual disease (MRD) evaluation in leukemia. Thisstudy aimed to develop a novel multiplex reverse transcription-nested polymerase chainreaction (RT-nPCR) assay to accurately and effectively detect10common generearrangements in adult acute lymphoblastic leukemia (ALL), examine theclinicopathologic characteristics and other genetic aberrations of ALL patientsexpressing different fusion genes, and analyze the relationship of fusion genes withother genetic aberrations, with the purpose of thoroughly understanding their clinicalsignificance in Chinese ALL patients. Meanwhile, we analyzed clinical characteristicsof15patients with FUS-ERG fusion genes, including morphology, immunophenotype,cytogenetics, molecular biology and MRD.METHODS：This study included256consecutive ALL patients who weretreated in the Department of Hematology, Chinese PLA General Hospital, betweenJanuary2007and December2011. Each sample was detected by MultiplexRT-nPCR.Fusion genes in90positive samples were verified using split-out PCR,cytogenetics, and FISH analysis. We analyzed clinical characteristics of15patientswith FUS-ERG fusion genes，which included9males and6females with the medianage of20years. Gene overexpression and mutations and MRD were detected byMultiplex RT-nRCR.RESULT: Our RT-nPCR assay had a positive detection rate of35.15%(90/256)for the10fusion genes. BCR-ABL1, FUS-ERG, MLL-AF4, ETV6-RUNX1,E2A-PBX1, dupMLL, MLL-AF10, MLL-ENL, SET-NUP214, and SIL-TAL1weredetected in36(14.06%),14(5.47%),14(5.47%),4(1.56%),4(1.56%),5(1.95%),4(1.56%),2(0.78%),2(0.78%), and5(1.95%) patients respectively. RT-nPCR resultswere further confirmed by split-out PCR, and cytogenetic and fluorescent in situhybridization (FISH) analysis revealed corresponding translocations and fusions in63and74cases, respectively. JAK2and IKZF1mutations were commonly detected inBCR-ABL1ALL patients, and HOX overexpression was highly correlated with MLL fusions and SET-NUP214.We found that the patients with FUS-ERG are characterized by a relativelyyounger age (median age,20years), and80%patients were B-ALL.15patientsachieved complete remission (CR) with the median time of34days (8-60days) afterinitial induction therapy, but soon relapsed at90to390days (median302days) afterCR. The one year and two year survival rate were46.7%and20%, respectively.10patients died, and5patients were alive among whom3patients received allogeneicHSC transplantation. Among the15patients, the mRNA transcription levelof ERGincreased in all patients, and that of MYC increased in10patients. The OS of patientswith lower copy level was longer, and similar results were obtained in analyzing EFS(p=0.047and0.016, respectively).Consistent detection of TLS/FUS-ERG transcripts atvarious clinical stages showed that the mRNA transcription level of TLS/FUS-ERGsignificantly decreased after hematological CR, but the mRNA transcription levelincreased after hematological relapse.CONCLUSIONS: We developed and tested a novel multiplex RT-nPCR methodfor molecular diagnosis. This technique is a useful way to stratify disease and selectappropriate, individualized therapeutic procedures. The approach of detecting geneticaberrations accurately, effectively and rapidly is extremely vital, and could potentiallybe developed for further use in diagnostic and prognostic studies of ALL.FUS-ERG tends to occur in B-ALL patients, and the OS and EFS were relativelyshort. Patients prone to be resistant to conventional chemotherapy, and should betreated with other more aggressive strategies such as stem cell transplantation in thefirst remission. The FUS-ERG fusion gene copy level in newly diagnosed patientsindirectly reflect the tumor burden in patients with leukemia, and the prognosis ofpatients with high copy levels is poor, with short EFS and OS. |
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