Objective: To explore the genetic characteristics, clinical features, and prognostic values of RAS mutations in patients with myelofibrosis (MF) . Methods: We analyzed 112-gene targeted sequencing data from 226 patients who had a diagnosis of either primary myelofibrosis (PMF) or post-polycythemia vera/post-essential thrombocythemia (post-PV MF and post-ET MF) from December 2011 to December 2019. A retrospective analysis of the genetic characteristics, clinical features, and prognosis of RAS mutations was performed. Results: Among 266 patients diagnosed PMF or post-PV/ET MF, RAS mutations were found in 14 (6.2%) cases, including 9 (4.0%) cases of NRAS mutations, 8 (3.5%) cases of KRAS mutations, and 3 (1.3%) cases of both NRAS and KRAS mutations. All of the NRAS mutations were located in codons 12 and 13. The median VAFs of RAS mutations were significantly lower than those of the driver mutations, confirming that they represent sub-clonal events that are acquired during the disease course. SETBP1, SRSF2, and MPL tended to be clustered with RAS mutations. Patients with RAS mutations had a higher number of additional oncogenic mutations (median, 3.36 vs 1.17, P<0.001) . RAS mutations had a statistically significant association with elevated monocyte cell counts (P=0.003) , lower platelet counts (P=0.026) , higher bone marrow blasts (P=0.022) , splenomegaly (P=0.005) , and very high-risk (VHR) karyotype abnormality percentage (P=0.031) . In univariate analysis, the OS of patients with NRAS mutations were significantly inferior in the entire MF and PMF cohorts (P=0.001, P=0.008) . In a multivariate model, NRAS retained an independent negative prognostic factor in PMF. Conclusion: RAS gene mutations were constantly related to elevated monocyte cell counts, lower platelet counts, higher bone marrow blasts, and VHR karyotype abnormality percentage that usually defined high-risk disease and often occurred as sub-clonal events. NRAS mutation is an independent poor prognostic factor in PMF.
目的： 分析骨髓纤维化（MF）患者RAS基因突变的分子特征及其临床特点和预后意义。 方法： 收集2011年12月至2019年12月在我中心有二代基因测序数据的226例MF患者临床资料，回顾性分析RAS基因突变特征、与临床和实验室参数之间的关系，及对总生存（OS）期的影响。 结果： 226例原发性骨髓纤维化（PMF）及真性红细胞增多症（PV）或原发性血小板增多症（ET）后骨髓纤维化（post-PV/ET MF）患者中，共14例（6.2%）检出RAS基因突变：NRAS突变9例（4.0%），KRAS突变8例（3.5%），NRAS及KRAS突变并存3例（1.3%）。所有NRAS突变均发生在第12-13号密码子。RAS基因突变多为亚克隆突变，常与SETBP1、SRSF2、MPL共同发生。伴RAS基因异常患者平均突变基因个数（3.36个）与无RAS基因异常组（1.77个）相比，差异有统计学意义（P<0.001）。RAS基因突变患者与无突变患者相比，外周血单核细胞水平升高（P=0.003），血小板水平减低（P=0.026），骨髓原始细胞比例升高（P=0.022），脾脏肋缘下≥10 cm患者比例更高（P=0.005）。突变组患者非常高危（VHR）染色体核型比例（18.2%，2/11）显著高于无突变组患者（2.3%，3/133）（P=0.031）。单因素分析中，NRAS基因突变的MF患者及PMF患者的OS时间较无突变患者显著缩短（P=0.001，P=0.008）。多因素分析显示，NRAS突变是影响OS的独立预后不良因素。 结论： RAS突变常与外周血单核细胞水平升高、血小板计数减低、骨髓原始细胞比例升高、VHR染色体核型等高危临床特征及实验室参数相关，多为发生在MF晚期的亚克隆突变。伴NRAS基因突变PMF及MF患者的OS时间显著缩短。.
Keywords: Mutation; Myelofibrosis; Prognosis; RAS gene.