RESUMO
BACKGROUND/AIM: There are no established biomarkers for immune checkpoint inhibitors (ICI) in colorectal cancer (CRC) with microsatellite stability (MSS) or proficient mismatch repair (pMMR). Therefore, this study aimed to identify biomarkers for ICI benefit in patients with pMMR by analyzing the down-regulated DNA repair-related genes involved in highly immunogenic and immune responses, and comparing their expression levels and clinical features. MATERIALS AND METHODS: Mismatch repair (MMR), tumor-infiltrating lymphocytes (TIL), and tumor mutation burden (TMB) were evaluated in 13 CRC cases and mRNA expression levels of 95 DNA repair-related genes were measured. DNA repair-related genes with reduced mRNA expression in the high immunogenicity and high immune response groups were identified. Then, the mRNA expression levels of the identified DNA repair-related genes were measured in 135 patients with CRC. Hierarchical cluster analysis was performed using the mRNA expression levels to compare the clinicopathological characteristics of each cluster. RESULTS: ATR, LIG4, and RAD52 mRNA levels were significantly down-regulated in the high immunogenicity group. GADD45B, SMUG1, and XRCC6 mRNA levels were significantly down-regulated in the high immune response group. Cases in the cluster with reduced mRNA expression of the six genes were pMMR cases. CD8 mRNA expression level was higher in this cluster than in the other clusters. CONCLUSION: Decreased mRNA expression levels of ATR, LIG4, RAD52, GADD45B, SMUG1, and XRCC6 genes were associated with high cytotoxic T cell and TMB levels, suggesting that these genes could serve as biomarkers for ICI efficacy in pMMR cases.
Assuntos
Biomarcadores Tumorais , Neoplasias Colorretais , Reparo do DNA , Linfócitos do Interstício Tumoral , Instabilidade de Microssatélites , Humanos , Neoplasias Colorretais/genética , Neoplasias Colorretais/imunologia , Neoplasias Colorretais/patologia , Biomarcadores Tumorais/genética , Feminino , Linfócitos do Interstício Tumoral/imunologia , Linfócitos do Interstício Tumoral/metabolismo , Masculino , Idoso , Pessoa de Meia-Idade , Reparo do DNA/genética , Mutação , Reparo de Erro de Pareamento de DNA/genética , Regulação Neoplásica da Expressão Gênica , Adulto , Inibidores de Checkpoint Imunológico/uso terapêutico , Inibidores de Checkpoint Imunológico/farmacologia , Idoso de 80 Anos ou maisRESUMO
We report the findings from a retrospective study to determine the optimum treatment strategy for local recurrence following radical resection of rectal cancer. In our department, among all 430 patients that underwent radical resection of rectal cancer from 2012 to 2018, there were 28 patients that developed local recurrence. Of those patients, 12 underwent surgical treatment(Op group)and 16 did not(N-Op group). In the Op group, 8 patients underwent radical resection, of which 2 patients remained recurrence-free, and the other 6 patients developed recurrence. In the N-Op group, 6 patients were treated with systemic chemotherapy alone, a further 6 patients had palliative irradiation in addition to systemic chemotherapy, and the other 4 selected best supportive care(2 patients were treated with palliative irradiation). In the 8 patients who had palliative irradiation, 7 showed a decrease in numerical rating scale(NRS)after irradiation. The adverse events of palliative irradiation were scrotal dermatitis in 1 patient and perianal inflammation in another 3 patients. Our surgical results for local recurrence of rectal cancer in our department were worse in terms of recurrence rate, so these findings suggest that the preoperative surgical strategy could be reviewed, as well as the actual surgical methods such as the optimal circumferential resection margin. Palliative irradiation was found to be useful for pain control. However, the occurrence of adverse events remains a concern.