Correlation between MSI, TMB, and TGFBR2 gene mutation in solid tumors.

e14558 Background: TGFBR2 encodes a receptor kinase which signals to downstream effectors in the TGF-ß signaling pathway. Recent research has shown that truncation mutations of TGFBR2 in gastric cancer with high tumor mutational burden. However, the relationship remains unclear in other solid tumors. Methods: We retrospectively analyzed the TGFBR2 mutations of 19370 Chinese patients with pan-cancer during 2019-2022 (Simcere Diagnosis, Nanjing, China) Next-generation sequencing (NGS) assessed somatic mutations in tumor tissue. We figured out TGFBR2 mutation frequency, TMB and MSI in TGFBR2-mutant, TGFBR2 wild-type. Results: We have detected TGFBR2 mutants in 536 (2.8%) samples. The top 5 frequent cancers were colorectal cancer (132, 24.7%), lung cancer (118, 22%), gastric cancer (78, 14.5%), biliary tract tumors(52, 9.7%) liver cancer (33, 6.2%).TGFBR2 variants included missense/indel/insert (238, 44.4%), truncation (219, 40.9%), splicing site variant (23, 4.3%), and CNV (33, 6.2%).The inactive variants include missense, which occurs in the TGFBR2 serine/threonine kinase domain, truncation and splicing site variant. However, truncation was the most common type, recurring in a few hot spots (p.K153Sfs*35, p.K153Afs*3, p.R520* ). And we found that the TMB and MSI in the TGFBR2 mutation group was significantly higher than that in the TGFBR2 wild-type group [TMB-H (TMB ≥10 musts/Mb): TGFBR2-MUT vs TGFBR2-WT, 41.2% vs 9.5%, p < 0.01; MSI-H: TGFBR2-MUT vsTGFBR2-WT, 27.4% vs1.7% p < 0.01]. In the TGFBR2 mutation group, It was also observed that TMB and MSI in the TGFBR2 truncation or splicing site mutant (INACT) group was significantly higher than that in the other mutant types (VUS) group [TMB-H (TMB ≥10 musts/Mb): TGFBR2-INACT vs TGFBR2-VUS, 51.0% vs 27.9%, p < 0.01; MSI-H: TGFBR2-INACT vs TGFBR2-VUS 39.4% vs 10.6% p < 0.01]. And then, we separately analyzed the correlation between MSI, TMB and TGFBR2 gene mutation in the top 5 frequent cancers. Over 60% of patients with TGFBR2 mutations in colorectal cancers have high TMB and MSI values [TMB-H (TMB ≥10 musts/Mb): TGFBR2-MUT vs TGFBR2-WT, 71.3% vs 12.8%, p < 0.01; MSI-H: TGFBR2-MUT vs TGFBR2-WT, 61.2% vs 3.0% p < 0.01]. Conclusions: We analyzed the distribution of TGFBR2 mutants in Chinese patients with solid tumors. Our data showed that TGFBR2 mutant was significantly associated with TMB-H and MSI-H, and this may be a potential molecular marker of immunotherapy. And studies have shown that the combination of TGF-β inhibitors and immune checkpoint inhibitors can increase the killing effect of T cells on tumors. In short, detection of TGFBR2 mutation has certain clinical significance.