Abstract: Objective： To investigate the clinical biological characteristics of EVI1 positive acute myeloid leukemia (AML) and its effect on early chemotherapy. Methods: The clinical and biological cha-racteristics of 33 AML patients with EVI1 positive were retrospectively analyzed in 361 AML patients who were diagnosed and treated in our institute from March 2015 to July 2016, and the clinical and biological features, and rates of the induced remission were compared between the intermediate risk and poor risk with EVI1 positive AML, moreover, the influential factors on complete remission (CR) were analyzed. The expression of EVI1/ABL was tested in 32 healthy donors to confirm the abnormal threshold of EVI1 expression. Results: The definition of EVI1 positive was that the quantitative expression of EVI1/ABL was more than 8.0%. The 33 AML patients with EVI1 positive were found in 361 newly diagnosed AML patients, in which the female and male patients were 17 and 16 respectively, the median age was 45 (18-67) years, with a median followup of 6.6 (0.7-13.2) months. Intermediate karyotype was found in 17 patients(including 9 patients with normal karyotypes,1 patient with +8);unfavorable karyotype was found in 14 patients ［including 7 patients with -7/7q-,4 patients with t (v;11q23)，3 patients with inv(3)/t(3;3)， and 2 patients without mitotic figures］. The rate of CR in the first induction chemotherapy was 42.4%, and the rate of total CR was 60.6%. According to the NCCN, 16 intermediate risk patients and poor risk patients were divided, without favorable risk patients. The rate of CR in the first induction chemotherapy were 68.8% and 17.6% (P=0.005) in the intermediate risk and poor risk respectively, that of total CR were 81.3% and 41.2%（P=0.032）, and the rates of relapse were 7.7% and 14.3%.Univariable analysis revealed that unfavorable karyotype could affect the rate of CR in the first reduction chemotherapy and that of total CR (P=0.004, 0.029). The poor risk patients had higher mortality (41.2% vs. 6.3%, P=0.039) and lower overall survival (OS)(P=0.012). Conclusion: EVI1 may be not an independent prognostic factor for the AML patients considering the appearance in the intermediate and poor risk patients. It predicts poor outcome in the EVI1 positive AML patients who have unfavorable karyocytes, such as -7/7q-, t(v;11q23), and inv(3)/t(3;3), and also a low rate of both CR in the first induction chemotherapy and total CR. It also has a low rate of longterm survival and high mortality in the AML patients with EVI1 positive, who may benefit from allogeneic bone marrow transplantation as soon as possible.

Key words: Acute myeloid leukemia, EVI1 gene, Rate of remission, Prognosis