[Genomic profiles and immune microenvironment of olfactory neuroblastoma].

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.