SYK Gene Mutations with TMB-H and MSI-H in Solid Tumors.

e14572 Background: Spleen tyrosine kinase ( SYK) gene encodes a cytoplasmic non-receptor tyrosine kinase (NRTK) and mediates signal transduction downstream of multiple transmembrane receptors, which plays an important role in a variety of signaling pathways. The change of SYK gene expression and gene mutations may lead to the formation and metastasis of multiple solid tumors. Previous studies on SYK mostly focus on the protein isomers and the methylation of SYK gene promoter. We previously used next generation sequencing (NGS) to explore SYK gene mutations on DNA level and found novel mutation types of SYK gene. Herein, NGS were performed to explore the relationship of SYK gene mutations with TMB and MSI in solid tumors for further clinical research. Methods: We retrospectively collected NGS detection data by 539-gene panel in 5648 patients with pan-cancer, of which 3931 patients by tumor tissue and 1717 patients by blood ctDNA, and screened out somatic SYK gene mutations. 539-gene panel contained all exon regions of SYK gene. Then we divided 5648 patients into four groups depending on whether SYK gene mutations: tumor tissue mutant group (T-mut) / non-mutant group (T-non-mut), and ctDNA mutant group (ctDNA-mut) / non-mutant group (ctDNA-non-mut). The difference in TMB between T-mut and T-non-mut groups; between ctDNA-mut and ctDNA-non-mut groups were analyzed via the Wilcoxon sign test respectively. The difference in MSI between T-mut and T-non-mut groups were analyzed via Fisher test. Results: In 5648 patients with solid tumors, 64 patients (48/3931 in tumor tissue and 16/1717 in blood ctDNA) were found harboring SYK gene mutations and the mutation frequency was 1.13%. TMB in T-mut group was higher than in T-non-mut group and significant difference of TMB was found via the Wilcoxon sign test (p = 5.3e-12) between the two groups. TMB in ctDNA-mut group was higher than in ctDNA-non-mut group and significant difference of TMB was found too (p = 4.6e-05). 12 patients were found MSI-H in T-mut group (12/48) and 53 patients were found MSI-H in T-non-mut group (35/3875). We found significant difference in the probability of MSI-H occurrence between the two groups by Fisher test (p = 6.531e-12, HR: 23.933, 95%CI: 10.734-50.415). Conclusions: This is the first report on the relationship between SYK gene mutations with TMB and MSI in solid tumors and we found that SYK gene mutations are associated with TMB-H and MSI-H in solid tumors. As a retrospective study in solid tumors, the conclusion and the mechanism need to be studied in the future.