嗅神经母细胞瘤的基因组特征和肿瘤免疫微环境研究

Genomic profiles and immune microenvironment of olfactory neuroblastoma

目的探讨嗅神经母细胞瘤(olfactory neuroblastoma, ONB)基因组特征和肿瘤免疫微环境特点。方法对2018年5月至2022年10月在北京同仁医院诊断的19例ONB患者, 根据Hyams分级系统分为低级别和高级别两组, 7例为低级别, 12例为高级别, 将ONB患者组织标本进行全外显子测序和多重免疫荧光分析。结果 18例ONB鉴定出929个非同义突变, 突变频率最高的癌症相关基因是CTNNB1(3/19)和ZNRF3(3/19), 突变频率最高的通路是Wnt和RAS通路。中位肿瘤突变负荷(TMB)0.45个突变/Mb(范围为0~3.25), 中位肿瘤新抗原负荷(TNB)9.39个新抗原/Mb(范围为0~38.30), 中位等位基因突变的肿瘤异质性(MATH)得分为16.95(范围为3.05~117.47)。多重免疫荧光结果显示1例表达细胞程序性死亡配体1(PD-L1;综合阳性评分>1), CD8+肿瘤浸润淋巴细胞(TIL)在肿瘤区域浸润的百分比中位数为1.08%。低级别组和高级别组在突变基因、突变通路、TMB、TNB、MATH、PD-L1和CD8+TIL表达差异无统计学意义(P>0.05), 但CD68^(+)巨噬细胞在低级别组肿瘤区域和总区域均显著多于高级别组(P<0.05), M1型巨噬细胞占CD68^(+)巨噬细胞80.52%。结论 CTNNB1和ZNRF3是ONB高频突变基因;PD-L1低表达和CD8+TIL数量低提示ONB可能对免疫治疗不敏感;M1型巨噬细胞在低级别ONB表达显著高于高级别, 提示可能参与ONB进展。

Objective:To investigate the genomic profiles and immune microenvironment of olfactory neuroblastoma(ONB).Methods:Nineteen ONB cases diagnosed in the Beijing Tongren Hospital from May 2018 to October 2022 were divided into low-grade and high-grade groups according to the Hyams grading system,including 7 low-grade and 12 high-grade ONB.Whole exome sequencing and multiplex immunofluorescence analyses were performed on tissue samples of these ONB.Results:A total of 929 nonsynonymous alterations were identified in 18 of the 19 ONB(18/19)cases.The most commonly altered cancer-related genes were CTNNB1(3/19)and ZNRF3(3/19).The most mutated oncogenic pathways were the WNT and RAS pathways.The median tumor mutation burden(TMB)was 0.45/Mb,ranging from 0 to 3.25.The median tumor neoantigen load(TNB)was 9.39 neoantigens/Mb,ranging from 0 to 38.30.The median allelic mutation tumor heterogeneity(MATH)score was 16.95,ranging from 3.05 to 117.47.Only one of the 19 cases expressed PD-L1(composite positive score,CPS>1)in the tumor cells.The median percentage of CD8+tumor-infiltrating lymphocyte(TIL)in the tumor region was 1.08%.No significant differences were observed between the low-and high-grade groups for mutant genes,mutant pathways,TMB,TNB,MATH,PD-L1 expression levels,or CD8^(+)TILs percentage(P>0.05).However,the low-grade group showed significantly more CD68+macrophages in both the tumor and total region than the high-grade group.Notably,CD68+CD163-macrophages accounted for an average of 80.52%of CD68+macrophages.Conclusions:CTNNB1 and ZNRF3 are the most commonly altered cancer-related genes.The low expression of PD-L1 and the low percentage of CD8^(+)TIL indicate that ONB might not be sensitive to immunotherapy.The percentage of M1-type macrophages in low-grade ONB is significantly higher than that in high-grade ONB,suggesting that M1-type macrophages may be involved in the progression of ONB from low-grade to high-grade.