[Clinical Significance of Common Gene Mutations in 53 Patients with Acute Myeloid Leukemia Harboring 11q23/MLL Rearrangements].

OBJECTIVE: To investigate the clinical significance of AML patients with 11q23/MLL rearrangement, and to evaluate the effect of those mutations on the AML patients. METHODS: 53 cases involving translocations of chromosome 11q23 were identified by chromosome banding analysis. MLL rearrangements were detected by fluorescence in situ hybridization and/or multiplex nested PCR. The samples were screened for mutations in the candidate genes FLT3-ITD, FLT3-TKD, TET2, N-RAS, ASXLI, EZH2, DNMT3, C-Kit, NPM1, WT1, CEBPA by using genomic DNA-PCR and deep-sequencing. RESULTS: 21/53 MLL-rearranged AML cases showed at least one additional chromosomal aberrations. The most common additional aberration was +8. Gene mutations were observed in 23 cases (43.4%) and most cases showed singal mutation. N-RAS mutation was more frequent (8 cases, 15.1%), followed by WT1 mutation in 4 cases (7.5%), FLT3-ITD mutation in 3 cases, ASXL1 mutation in 2 cases, DNMT3A mutation in 2 cases, EZH2 mutation in 1 case, c-Kit17 mutation in 1 case, FLT3-TKD mutation in 1 case, and FLT3-ITD and TKD mutation coexistent in 1 case. No mutation was detected in CEBPA, NPM1, C-KIT8, TET2. Median OS for gene mutated patients was 8.5 months and 13 months for no mutated patients. Median OS for patients who received hematopoietic stem cell transplantation (HSCT) was 22.5 months and 7.5 months for patients who olny received chemotherapy. CONCLUSION: A relatively high mutation frequency is observed in AML patients with 11q23/MLL rearrangements and most cases shows single mutation. The RAS signaling pathway alterations are most common. Gene mutation does not affect the OS of these patients, who show poor prognosis. A significantly higher Hb at initial diagnosis in FLT3 mutated patients is significantly higher than that in FLT3 wild-type cases. Patients who underwent HSCT show a better prognosis than those only received chemotherapy.

p210 BCR/ABL1 as a secondary change in a patient with acute myelomonocytic leukemia (M4Eo) with inv(16).

t(9;22) as a secondary change of inv(16) is a rare chromosome aberration in de novo acute myeloid leukemia (AML). Here, we report the case of a 31-year-old man with this rare abnormality. Karyotypic analysis showed a complex chromosome aberration:46,XY,der(8)t(8;10)(p23;q25),der(10)t(8;10)t(10;16)(p13;q22),der(16)inv(16)(p13q22)t(10;16)[4] and 46,XY,idem,t(9;22)(q34;q11)[6]. Fluorescence in situ hybridization detected both the CBFB and the BCR/ABL1 rearrangements. CBFB/MYH11 (A type) and BCR/ABL1 (b3a2) fusion transcripts were both detected by real-time quantitative RT-PCR. The patient was treated with standard AML chemotherapy and autologous peripheral blood stem cell transplantation. He also received imatinib (400 mg/day) during the chemotherapy intervals and after transplantation. Molecular remission was achieved at the beginning of the third chemotherapy and he remained in remission until the last follow-up (22 months after diagnosis). To our knowledge, this is the first reported case of de novo AML in which has p210(BCR/ABL1) occurred as a secondary change of inv(16).