Objective To investigate the clinical characteristics of patients with chronic myeloid leukemia (CML) in chronic phase with deletion and non-deletion of the argininosuccinate synthesis gene (ASS gene) on the derivative chromosome 9. Methods The clinical data of patients with CML initially treated with imatinib and BCR/ABL1/ASS1 3-color fusion probe to detect ASS gene deletion were analyzed. The patients were divided into deletion group (n=27) and non-deletion group (n=92). Clinical characteristics, treatment effects, and prognosis were analyzed. Results The average age of 119 patients was 37.22±12.72 years old. The sokal score differed between the deletion and non-deletion groups (χ²=4.304, P=0.038). No statistically significant difference in other general characteristics was found (P > 0.05). The 3-month CCyR rate, 6-month CCyR rate, and BCR-ABL^IS≤ 1% rate in the deletion group were lower than those in the non-deletion group (P < 0.05). The median follow-up of 119 patients was 35.0 (3.0-60.0) months. The PFS in the deletion group was lower than that in the non-deletion group (χ²=4.293, P=0.038). Overall survival was not significantly different between the two groups (χ²=0.008, P=0.931). Conclusion The deletion of the ASS gene in patients with chronic CML is related to the poor efficacy of imatinib treatment, poor prognosis, and high risk of disease progression.

OBJECTIVETo analyze the association of different types of ABL tyrosine point mutations and imatinib resistance to probe the relation between ABL tyrosine point mutations and the prognosis of patients with chronic myeloid leukemia (CML).

METHODSNested reverse transcriptasepolym erase chain reaction was performed on samples from 70 patients to amplify the ABL kinase domain. Then, the amplified product was purified and sequenced in both direction. The homologous analysis was performed in combination of clinical data.

RESULTSThe ABL domain point mutations were detected in 32 patients (45.7%) including 16 patients in chronic phase (CP), 6 patients in accelerated phase(AP)and 10 patients in blast phase (BP), which were detected as T315I, E255K, C475Y, Y253H, G321W, G250E, F317L, E258K, F359V, E459K and F311I, respectively. Sokal score with intermediate and high risk and Ph+ chromosome with complex karyotype were important risk factors for ABL domain point mutations. The 5-year overall survival (OS) was not significantly different between the patients with or without ABL domain point mutations (78.1% vs 84.2%, P=0.985), while the 5-year cumulative event-free survival (EFS) of two groups were 34.4% and 68.4% (P=0.034), respectively. The rate of complete cytogenetic response was higher in patients treated with allogenic hematopetic stem cell transplantation (allo-HSCT) compared with patients merely treated with second-generation tyrosine kinase inhibitors or chemotherapeutics (P=0.001).

CONCLUSIONPatients with ABL domain point mutations had poor efficacy and prognosis compared to those without ABL domain point mutations. Detection of ABL domain point mutations in CML-CP was helpful for the adjustment of therapeutic options and improvement of prognosis. And allo-HSCT was a more effective therapy for patients with advanced phase.

Adolescent ; Adult ; Aged ; Benzamides ; therapeutic use ; Child ; Drug Resistance, Neoplasm ; Female ; Humans ; Imatinib Mesylate ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; drug therapy ; genetics ; Male ; Middle Aged ; Piperazines ; therapeutic use ; Point Mutation ; Prognosis ; Proto-Oncogene Proteins c-abl ; genetics ; Pyrimidines ; therapeutic use ; Young Adult