急性未分化白血病和混合表型急性白血病患者分子特征及临床分析

Clinical and Molecular Characteristics of Acute Undifferentiated Leukemia and Mixed Phenotypic Acute Leukemia

目的探讨急性未分化白血病(AUL)和混合表型急性白血病(MPAL)患者分子特征及临床预后。方法回顾性总结了2012年3月—2018年12月在苏州大学附属第一医院初诊为AUL和MPAL的患者,获取新鲜骨髓或血液标本,分析患者的骨髓细胞形态、免疫分型、染色体核型、融合基因及基因突变。所有计算均使用SPSS 20.0软件包。采用Fisher精确概率检验分析了AUL和MPAL基因突变的相互关系。结果AUL患者(n=14)的临床特征主要表现为男性9例(64.29%),女性5例(35.71%)。中位年龄为54岁(范围:15~73岁)。免疫表型表现为CD34(12/14,85.71%)、CD33(7/14,50.00%)、HLA-DR(5/14,35.71%)共同表达,CD38阴性。细胞遗传学研究发现染色体核型异常8例(57.14%),包括3例(21.43%)患者复杂核型(≥3畸变)。二代测序显示9/11(81.82%)的患者至少伴有1个基因突变,每例患者的基因突变中位数为4个(范围:2~7个)。PHF6突变是患者中最常见的基因突变(5/11,45.45%),3/11(27.27%)患者伴有ETV6、ASXL1、NRAS和FLT3突变。而在25例MPAL患者中10/25(40.00%)检测到CEBPA突变,6/25(24.00%)检测到WT1突变,5/25(20.00%)检测到KRAS突变。与MPAL相比,AUL患者PHF6突变率显著增高(45.45%vs 12.00%,P=0.040)。14例AUL患者中位随访时间为359 d。首次诊断的一年总生存率为80.0%(95%CI:44.9%~115.1%),一年无病生存率为62.5%(95%CI:20.8%~104.3%)。首次诱导化疗后,仅有3例(3/7,42.86%)患者完全缓解,2例(2/7,28.57%)患者死于复发。2例患者接受异基因造血干细胞移植(allogeneic hematopoietic stem cell transplantation,Allo-HSCT)。其中1例死于移植术后77 d复发。在3例有PHF突变的随访患者中,2例患者首次诱导化疗后未达到完全缓解,其中1例复发死亡。结论AUL患者CD33、CD34、HLA-DR频繁表达,CD38不表达,具有干细胞样特征。细胞遗传学特征没有共性。PHF6基因突变频率较高,且PHF6突变患者诱导缓解率较低,预后较差。

Objective To investigate the molecular characteristics and clinical prognosis of patients with acute undifferentiated leukemia(AUL)and mixed phenotype acute leukemia(MPAL).Methods The AUL and MPAL patients diagnosed and/or treated at the First Affiliated Hospital of Soochow University from 2012 to 2018 were retrospectively summarized.Fresh bone marrow or blood specimens were obtained from AUL and MPAL patients at diagnosis and submitted for morphology and cytochemical analysis,flow cytometry immunophenotyping,chromosome analysis,multiplex-PCR and next-generation sequencing(NGS).All calculations were performed using the SPSS 20.0 software package.Fisher exact probability test was used to analyze the interrelation of AUL and MPAL gene mutations.Results Clinical features of AUL cohort showed that 9(64.29%)males and 5(35.71%)females were included.The median age at the time of diagnosis was 54(range:15-73)years old.Immunophenotyping revealed the common expression of CD34(12/14,85.71%),CD33(7/14,50.00%),HLA-DR(5/14,35.71%)as well as negative CD38.Cytogenetic studies found chromosomal abnormalities in 8(57.14%)of them,including 3(21.43%)patients with complex karyotypes(≥3 aberrations).NGS showed that nine out of eleven AUL patients were found with 39 gene mutations.PHF6 mutation was the most frequently mutated gene occurring in 5/11(45.45%)patients,followed by ETV6,ASXL1,NRAS and FLT3 in 3/11(27.27%)patients.Meanwhile,CEBPA was detected in 10/25(40.00%)MPAL patients,WT1 in 6(24.00%)patients and KRAS in 5(20.00%)patients.In comparison to MPAL,AUL patients had a significantly higher mutation rate in PHF6(45.45%vs 12.00%,P=0.040),which hinted PHF6 might be related to AUL evolution.Among the 14 AUL patients,the median follow-up time was 359 days.The one-year overall survival from first diagnosis was 80.0%(95%CI 44.9%-115.1%)and one-year disease-free survival was 62.5%(95%CI 20.8%-104.3%).Only 3 patients(3/7,42.86%)attained complete remission after first induction chemotherapy,and 2 patients(2/7,28.57%)died of relapse.2 patients received allogeneic hematopoietic stem cell transplantation(Allo-HSCT).1 of them relapsed 77 days after transplantation and died of relapse.Among the 3 followed-up patients with PHF mutations,2 patients didn't attain complete remission after first induction chemotherapy,including 1 death of relapse.Conclusion AUL patients reveals a frequent expression of CD33,CD34,and HLA-DR without expression of CD38,which showed the stem-cell-like characteristics of this leukemia subtype without cytogenetic common features.There was a higher frequency of PHF6 gene mutations and patients with PHF6 mutations had a low induced relieving rate and relatively poor prognosis.