Non­small cell lung cancer carrying PBRM1 mutation suggests an immunologically cold phenotype leading to immunotherapy failure even with high TMB.

High tumor mutation load (TMB-H, or TMB ≥ 10) has been approved by the U.S. FDA as a biomarker for pembrolizumab treatment of solid tumors, including non­small cell lung cancer (NSCLC). Patients with cancer who have immunotherapy-resistant gene mutations cannot achieve clinical benefits even in TMB-H. In this study, we aimed to identify gene mutations associated with immunotherapy resistance and further informed mechanisms in NSCLC. A combined cohort of 350 immune checkpoint blockade-treated patients from Memorial Sloan Kettering Cancer Center (MSKCC) was used to identify genes whose mutations could negatively influence immunotherapy efficacy. An external NSCLC cohort for which profession-free survival (PFS) data were available was used for independent validation. CIBERSORT algorithms were used to characterize tumor immune infiltrating patterns. Immunogenomic features were analysed in the TCGA NSCLC cohort. We observed that PBRM1 mutations independently and negatively influence immunotherapy efficacy. Survival analysis showed that the overall survival (OS) and PFS of patients with PBRM1 mutations (MT) were significantly shorter than the wild type (WT). Moreover, compared with PBRM1-WT/TMB-H group, OS was worse in the PBRM1-MT/TMB-H group. Notably, in patients with TMB-H/PBRM1-MT, it was equal to that in the low-TMB group. The CIBERSORT algorithm further confirmed that the immune infiltration abundance of CD8+ T cells and activated CD4+ memory T was significantly lower in the MT group. Immunogenomic differences were observed in terms of immune signatures, T-cell receptor repertoire, and immune-related genes between WT and MT groups. Nevertheless, we noticed an inverse relationship, given that MT tumors had a higher TMB than the WT group in MSKCC and TCGA cohort. In conclusion, our study revealed that NSCLC with PBRM1 mutation might be an immunologically cold phenotype and exhibited immunotherapy resistance. NSCLC with PBRM1 mutation might be misclassified as immunoresponsive based on TMB.

A novel immunogenomic signature to predict prognosis and reveal immune infiltration characteristics in pancreatic ductal adenocarcinoma.

Background: The immune response in the tumor microenvironment (TME) plays a crucial role in cancer progression and recurrence. We aimed to develop an immune-related gene (IRG) signature to improve prognostic predictive power and reveal the immune infiltration characteristics of pancreatic ductal adenocarcinoma (PDAC). Methods: The Cancer Genome Atlas (TCGA) PDAC was used to construct a prognostic model as a training cohort. The International Cancer Genome Consortium (ICGC) and the Gene Expression Omnibus (GEO) databases were set as validation datasets. Prognostic genes were screened by using univariate Cox regression. Then, a novel optimal prognostic model was developed by using least absolute shrinkage and selection operator (LASSO) Cox regression. Cell type identification by estimating the relative subsets of RNA transcripts (CIBERSORT) and estimation of stromal and immune cells in malignant tumors using expression data (ESTIMATE) algorithms were used to characterize tumor immune infiltrating patterns. The tumor immune dysfunction and exclusion (TIDE) algorithm was used to predict immunotherapy responsiveness. Results: A prognostic signature based on five IRGs (MET, ERAP2, IL20RB, EREG, and SHC2) was constructed in TCGA-PDAC and comprehensively validated in ICGC and GEO cohorts. Multivariate Cox regression analysis demonstrated that this signature had an independent prognostic value. The area under the curve (AUC) values of the receiver operating characteristic (ROC) curve at 1, 3, and 5 years of survival were 0.724, 0.702, and 0.776, respectively. We further demonstrated that our signature has better prognostic performance than recently published ones and is superior to traditional clinical factors such as grade and tumor node metastasis classification (TNM) stage in predicting survival. Moreover, we found higher abundance of CD8+ T cells and lower M2-like macrophages in the low-risk group of TCGA-PDAC, and predicted a higher proportion of immunotherapeutic responders in the low-risk group. Conclusions: We constructed an optimal prognostic model which had independent prognostic value and was comprehensively validated in external PDAC databases. Additionally, this five-genes signature could predict immune infiltration characteristics. Moreover, the signature helped stratify PDAC patients who might be more responsive to immunotherapy.

Characterization of IL-10-producing regulatory B cells in thymoma.

BACKGROUND: Regulatory B cells (Bregs) are a subset of B cells that secrete interleukin 10 (IL-10) and play a vital role in suppressing the immune response. The aim of this study was to evaluate the proportion of Bregs in patients with thymoma. METHODS: The proportions of subgroups of Bregs in 23 patients with thymoma and 15 healthy controls were detected by flow cytometry. The serum IL-2, IL-4, IL-6, IL-10, IL-17A, IFN-γ, and TNF-α levels of the subjects were measured using a cytometric bead array (CBA). RESULTS: The proportions of circulating IL-10+ B cells, IL-10+CD24hiCD38hi Bregs, and IL-10+CD24hiCD27+ Bregs and the serum IL-10 level were significantly higher in patients with thymoma than in the control group and were negatively correlated with the Karnofsky Performance Scale (KPS) score. The serum levels of cytokines IL-2, IL-6, IFN-γ, and TNF-α were higher and serum IL-17A level was lower in patients with thymoma. Patients with advanced-stage thymoma exhibited significantly higher proportions of IL-10-producing Bregs and a higher serum IL-10 level. After tumour resection, the frequency of circulating IL-10+CD24hiCD38hi Bregs and the serum IL-10 level were significantly decreased in patients with thymoma. The serum IL-10 levels exhibited the best accuracy in assessing the risk of thymoma occurrence in this study. CONCLUSIONS: The expression of IL-10 produced by Bregs is increased in patients with thymoma, particularly those with advanced-stage disease, which may suggest that Bregs are involved in the pathogenesis and progression of thymoma.

Upregulated TIGIT+ and Helios+ regulatory T cell levels in bronchoalveolar lavage fluid of NSCLC patients.

BACKGROUND: The tumour microenvironment reshapes the specific gene expression of regulatory T cells (Tregs). A better definition of Treg subpopulations in the non-small-cell lung cancer (NSCLC) milieu is expected to clarify the identity and functional mode of Tregs and lead to the identification of better therapeutic targets. METHODS: A total of 53 peripheral blood (PB) samples from 36 NSCLC patients and 17 control subjects and 42 matched bronchoalveolar lavage fluid (BALF) samples from 31 NSCLC patients and 11 control subjects were obtained to examine the frequencies of Treg subgroups through flow cytometry. Fifteen PB samples from healthy individuals were collected to explore the differential functions of Treg subsets. The PB samples of 5 patients after chemotherapy were obtained to evaluate the effect of chemotherapy on Treg subsets. Serum CYFRA 21-1 levels in NSCLC patients were determined using an electrochemiluminescence immunoassay. RESULTS: The proportions of CD4+CD25+FoxP3+ Tregs in both PB and BALF were increased in NSCLC patients compared to controls. In BALF, the TIGIT+, Helios+, and TIGIT+Helios+ Treg subset levels were significantly elevated; the levels of the last two subsets were associated with NSCLC development, while the level of TIGIT-Helios- Tregs was decreased. The proportions of overall Tregs and TIGIT+, Helios+, and Helios+TIGIT+ Tregs were positively correlated with the serum CYFRA 21-1 levels in all patients. Functional differences were observed between Helios+TIGIT+ and Helios-TIGIT- Tregs. After chemotherapy, regardless of the reduction in serum CYFRA 21-1 levels, the proportions of Tregs and Treg subsets did not change. CONCLUSIONS: Elevated TIGIT+Helios+ and Helios+ Treg levels may play a role in NSCLC tumour progression, and targeting TIGIT and Helios on Tregs may be an effective treatment for NSCLC.