Housekeeping U1 snRNA facilitates antiviral innate immunity by promoting TRIM25-mediated RIG-I activation.

U1 small nuclear RNA (snRNA) is an abundant and evolutionarily conserved 164-nucleotide RNA species that functions in pre-mRNA splicing, and it is considered to be a housekeeping non-coding RNA. However, the role of U1 snRNA in regulating host antiviral immunity remains largely unexplored. Here, we find that RNVU1-18, a U1 pseudogene, is significantly upregulated in the host infected with RNA viruses, including influenza and respiratory syncytial virus. Overexpression of U1 snRNA protects cells against RNA viruses, while knockdown of U1 snRNA leads to more viral burden in vitro and in vivo. Knockout of RNVU1-18 is sufficient to impair the type I interferon-dependent antiviral innate immunity. U1 snRNA is required to fully activate the retinoic acid-inducible gene I (RIG-I)-dependent antiviral signaling, since it interacts with tripartite motif 25 (TRIM25) and enhances the RIG-I-TRIM25 interaction to trigger K63-linked ubiquitination of RIG-I. Our study reveals the important role of housekeeping U1 snRNA in regulating host antiviral innate immunity and restricting RNA virus infection.

IL-2Rα-biased agonist enhances antitumor immunity by invigorating tumor-infiltrating CD25+CD8+ T cells.

To avoid regulatory T cell promotion and vascular toxicity, the interleukin-2 receptor-ß/interleukin-2 receptor-γ (IL-2Rßγ)-biased approach is used by most IL-2 analogs in immuno-oncology. However, recent clinical disappointments in these IL-2 agonists have questioned this strategy. Here we show that both wild-type (IL-2wt) and IL-2Rßγ-attenuated (IL-2α-bias) agonists that preserve IL-2Rα (CD25) activities can effectively expand tumor-specific CD8+ T cells (TSTs) and exhibit better antitumor efficacy and safety than the 'non-α' counterpart (IL-2nα). Mechanistically, TSTs coexpress elevated CD25 and PD-1 and are more susceptible to stimulation by IL-2Rα-proficient agonists. Moreover, the antitumor efficacy of anti-PD-1 depends on activation of PD-1+CD25+ TSTs through autocrine IL-2-CD25 signaling. In individuals with cancer, a low IL-2 signature correlates with non-responsiveness to anti-PD-1 treatment. In mouse models, IL-2α-bias, but not IL-2nα, restores the IL-2 signature and synergizes with anti-PD-1 to eradicate large established tumors. These findings underscore the indispensable function of CD25 in IL-2-based immunotherapy and provide rationales for evaluating IL-2Rα-biased agonists in individuals with cancer.

Classification of Tumor Immune Microenvironment According to Programmed Death-Ligand 1 Expression and Immune Infiltration Predicts Response to Immunotherapy Plus Chemotherapy in Advanced Patients With NSCLC.

INTRODUCTION: According to mechanisms of adaptive immune resistance, tumor immune microenvironment (TIME) is classified into four types: (1) programmed death-ligand 1 (PD-L1)-negative and tumor-infiltrating lymphocyte (TIL)-negative (type I); (2) PD-L1-positive and TIL-positive (type II); (3) PD-L1-negative and TIL-positive (type III); and (4) PD-L1-positive and TIL-negative (type IV). However, the relationship between the TIME classification model and immunotherapy efficacy has not been validated by any large-scale randomized controlled clinical trial among patients with advanced NSCLC. METHODS: On the basis of RNA-sequencing and immunohistochemistry data from the ORIENT-11 study, we optimized the TIME classification model and evaluated its predictive value for the efficacy of immunotherapy plus chemotherapy. RESULTS: PD-L1 mRNA expression and immune score calculated by the ESTIMATE method were the strongest predictors for the efficacy of immunotherapy plus chemotherapy. Therefore, they were determined as the optimized definition of the TIME classification system. When compared between combination therapy and chemotherapy alone, only the type II subpopulation with high immune score and high PD-L1 mRNA expression was significantly associated with improved progression-free survival (PFS) (hazard ratio = 0.12, 95% confidence interval: 0.06-0.25, p < 0.001) and overall survival (hazard ratio = 0.27, 95% confidence interval: 0.13-0.55, p < 0.001). In the combination group, the type II subpopulation had a much longer survival time, not even reaching the median PFS or overall survival, but the other three subpopulations were susceptible to having similar PFS. In the chemotherapy group, there was no marked association between survival outcomes and TIME subtypes. CONCLUSIONS: Only patients with both high PD-L1 expression and high immune infiltration could benefit from chemotherapy plus immunotherapy in first-line treatment of advanced NSCLC. For patients lacking either PD-L1 expression or immune infiltration, chemotherapy alone might be a better treatment option to avoid unnecessary toxicities and financial burdens.

Sintilimab versus docetaxel as second-line treatment in advanced or metastatic squamous non-small-cell lung cancer: an open-label, randomized controlled phase 3 trial (ORIENT-3).

BACKGROUND: Treatment options for Chinese patients with locally advanced or metastatic squamous-cell non-small-cell lung cancer (sqNSCLC) after failure of first-line chemotherapy are limited. This study (ORIENT-3) aimed to evaluate the efficacy and safety of sintilimab versus docetaxel as second-line treatment in patients with locally advanced or metastatic sqNSCLC. METHODS: ORIENT-3 was an open-label, multicenter, randomized controlled phase 3 trial that recruited patients with stage IIIB/IIIC/IV sqNSCLC after failure with first-line platinum-based chemotherapy. Patients were randomized in a 1:1 ratio to receive either 200 mg of sintilimab or 75 mg/m2 of docetaxel intravenously every 3 weeks, stratified by the Eastern Cooperative Oncology Group performance status. The primary endpoint was overall survival (OS) in the full analysis set (FAS). Secondary endpoints included progression-free survival (PFS), objective response rate (ORR), disease control rate (DCR), duration of response (DoR) and safety. RESULTS: Between August 25, 2017, and November 7, 2018, 290 patients were randomized. For FAS, 10 patients from the docetaxel arm were excluded. The median OS was 11.79 (n = 145; 95% confidence interval [CI], 10.28-15.57) months with sintilimab versus 8.25 (n = 135; 95% CI, 6.47-9.82) months with docetaxel (hazard ratio [HR]: 0.74; 95% CI, 0.56-0.96; P = 0.025). Sintilimab treatment significantly prolonged PFS (median 4.30 vs. 2.79 months; HR: 0.52; 95% CI, 0.39-0.68; P < 0.001) and showed higher ORR (25.50% vs. 2.20%, P < 0.001) and DCR (65.50% vs. 37.80%, P < 0.001) than the docetaxel arm. The median DoR was 12.45 (95% CI, 4.86-25.33) months in the sintilimab arm and 4.14 (95% CI, 1.41-7.23) months in the docetaxel arm (P = 0.045). Treatment-related adverse events of grade ≥ 3 were reported in 26 (18.1%) patients in the sintilimab arm and 47 (36.2%) patients in the docetaxel arm. Exploratory biomarker analysis showed potential predictive values of expression levels of two transcription factors, including OVOL2 (HR: 0.35; P < 0.001) and CTCF (HR: 3.50; P < 0.001)，for sintilimab treatment. CONCLUSIONS: Compared with docetaxel, sintilimab significantly improved the OS, PFS, and ORR of Chinese patients with previously treated locally advanced or metastatic sqNSCLC.

Clinical and biomarker analyses of sintilimab versus chemotherapy as second-line therapy for advanced or metastatic esophageal squamous cell carcinoma: a randomized, open-label phase 2 study (ORIENT-2).

This randomized, open-label, multi-center phase 2 study (NCT03116152) assessed sintilimab, a PD-1 inhibitor, versus chemotherapy in patients with esophageal squamous cell carcinoma after first-line chemotherapy. The primary endpoint was overall survival (OS), while exploratory endpoint was the association of biomarkers with efficacy. The median OS in the sintilimab group was significantly improved compared with the chemotherapy group (median OS 7.2 vs.6.2 months; P = 0.032; HR = 0.70; 95% CI, 0.50-0.97). Incidence of treatment-related adverse events of grade 3-5 was lower with sintilimab than with chemotherapy (20.2 vs. 39.1%). Patients with high T-cell receptor (TCR) clonality and low molecular tumor burden index (mTBI) showed the longest median OS (15.0 months). Patients with NLR < 3 at 6 weeks post-treatment had a significantly prolonged median OS (16.6 months) compared with NLR ≥ 3. The results demonstrate a significant improvement in OS of sintilimab compared to chemotherapy as second-line treatment for advanced or metastatic ESCC.

Combined strategies for effective cancer immunotherapy with a novel anti-CD47 monoclonal antibody.

CD47 is a widely expressed cell-surface protein that regulates phagocytosis mediated by cells of the innate immune system, such as macrophages and dendritic cells. CD47 serves as the ligand for a receptor on these innate immune cells, signal regulatory protein (SIRP)-α, which in turn inhibits phagocytosis. Several targeted CD47 therapeutic antibodies have been investigated clinically; however, how to improve its therapeutic efficacy remains unclear. Herein, we developed a CD47 blocking antibody, named IBI188, that could specifically block the CD47-SIRP-α axis, which transduces the "don't eat me" signal to macrophages. In vitro phagocytosis assays demonstrated the pro-phagocytosis ability of IBI188. Furthermore, several in vivo models were chosen to evaluate the anti-tumor efficacy of IBI188. IBI188 treatment upregulated cell movement- and inflammation-related genes in macrophages. Synergism was observed when combined with an anti-CD20 therapeutic antibody, whose function depends on antibody-dependent cellular cytotoxicity/phagocytosis (ADCC/ADCP). CD47 expression was evaluated following azacytidine (AZA) treatment, a standard-of-care for patients with multiple myeloma; enhanced anti-tumor efficacy was observed in the combination group in AML xenograft models. Notably, IBI188 treatment increased vascular endothelial growth factor-A (VEGF-A) levels in a solid tumor model, and combined treatment with an anti-VEGF-A antibody and IBI188 resulted in an enhanced anti-tumor effect. These data indicate that IBI188 is a therapeutic anti-CD47 antibody with anti-tumor potency, which can be enhanced when used in combination with standard-of-care drugs for cancer treatment.

Cancer immune therapy with PD-1-dependent CD137 co-stimulation provides localized tumour killing without systemic toxicity.

Expression of the cell surface receptor CD137 has been shown to enhance anti-cancer T cell function via engagement with its natural ligand 4-1BBL. CD137 ligation with engineered ligands has emerged as a cancer immunotherapy strategy, yet clinical development of agonists has been hindered by either toxicity or limited efficacy. Here we show that a CD137/PD-1 bispecific antibody, IBI319, is able to overcome these limitations by coupling CD137 activation to PD-1-crosslinking. In CT26 and MC38 syngeneic mouse tumour models, IBI319 restricts T cell co-stimulation to PD-1-rich microenvironments, such as tumours and tumour-draining lymph nodes, hence systemic (liver) toxicity arising from generalised T cell activation is reduced. Besides limiting systemic T cell co-stimulation, the anti-PD-1 arm of IBI319 also exhibits checkpoint blockade functions, with an overall result of T and NK cell infiltration into tumours. Toxicology profiling in non-human primates shows that IBI319 is a well-tolerated molecule with IgG-like pharmacokinetic properties, thus a suitable candidate for further clinical development.

Assessment of TMB, PD-L1, and lymphocyte to monocyte ratio as predictive potential in a phase Ib study of sintilimab in patients with advanced solid tumors.

BACKGROUND: Sintilimab is a humanized monoclonal antibody against the programmed cell death 1 (PD-L1). We aimed to assess the safety and activity of sintilimab monotherapy or in combination with chemotherapy in advanced solid tumors. METHODS: This phase Ib study included six cohorts. Cohort A-C were sintilimab monotherapy settings, and enrolled pretreated patients (2/3 L cohorts). Cohort D-F were treatment-naïve patients (1 L cohorts), and received sintilimab plus different chemotherapies. The primary endpoints were safety and objective response rate (ORR). Exploratory endpoints were potential biomarkers for the prognosis after treatment, such as tumor mutation burden scores (TMB), PD-L1 and lymphocyte-to-monocyte ratio (LMR). RESULTS: The ORR was 14.6% in the 2/3 L cohorts (n=146), and 73.2% in the 1 L cohorts (n=61). The incidence of grade 3-4 adverse events occurred in 55 patients (37.7%) in 2/3 L cohorts, and in 38 (62.3%) in 1 L cohorts. 157 patients had available TMB scores, and in 2/3 L cohorts, patients in the high TMB groups (TMB≥10) showed a longer progression-free survival (PFS) and overall survival (OS) than those in the low TMB groups (TMB<10). No significant differences in PFS and OS were observed across different PD-L1 groups in both 1 L and 2/3 L cohorts. A high LMR was significantly associated with an improved PFS in 1 L cohorts (P=0.022). CONCLUSION: Sintilimab alone or combined with chemotherapy had a tolerable safety profile in solid tumors. The combination therapy showed a favorable activity with advanced non-small cell lung cancer and gastric or esophagogastric junction adenocarcinoma. LMR might be a prognostic factor for the combination regimen in these patients. TRIAL REGISTRATION: ClinicalTrials.gov, number NCT02937116. Registered 18 October 2016.

Updated Overall Survival Data and Predictive Biomarkers of Sintilimab Plus Pemetrexed and Platinum as First-Line Treatment for Locally Advanced or Metastatic Nonsquamous NSCLC in the Phase 3 ORIENT-11 Study.

INTRODUCTION: Sintilimab plus chemotherapy significantly prolonged progression-free survival (PFS) compared with chemotherapy alone in nonsquamous NSCLC in the ORIENT-11 study. Updated overall survival (OS) and PFS data and corresponding biomarker analyses are reported here. METHODS: In this study, a total of 397 patients with previously untreated, locally advanced or metastatic nonsquamous NSCLC were assigned to sintilimab plus chemotherapy combination treatment (combo) group or placebo plus chemotherapy treatment group. The patients were stratified by programmed death-ligand 1 (PD-L1) expression levels. Immune signature profiles from tumor RNA sequencing and PD-L1 immunohistochemistry were correlated with clinical outcome to identify predictive biomarkers. RESULTS: As of January 2021, with median follow-up of 22.9 months, median OS was significantly improved in the combo group compared with the placebo plus chemotherapy treatment group (not reached versus 16.8 mo; hazard ratio [HR] = 0.60, 95% confidence interval [CI]: 0.45-0.79, p = 0.0003). High or medium immune cell infiltration was strongly associated with improved PFS in the combo group, in contrast to absent or low immune cell infiltration, which suggests that chemotherapy could not prime "immune deserts" to obtain benefit from programmed cell death protein-1 inhibition. In particular, high major histocompatibility complex (MHC) class II presentation pathway expression was significantly correlated with prolonged PFS (HR = 0.32, 95% CI: 0.19-0.54, p < 0.0001) and OS (HR = 0.36, 95% CI: 0.20-0.64, p = 0.0005) in the combo group. Importantly, patients with low or absent PD-L1 but high MHC class II expression could still benefit from the combo treatment. In contrast, MHC class I antigen presentation pathway was less relevant in this combination setting. CONCLUSIONS: The addition of sintilimab to chemotherapy resulted to significantly longer OS in nonsquamous NSCLC. Expression of MHC class II antigen presentation pathway could identify patients benefiting most from this combination.

Landscape of the genome and host cell response of Mycobacterium shigaense reveals pathogenic features.

A systems approach was used to explore the genome and transcriptome of Mycobacterium shigaense, a new opportunistic pathogen isolated from a patient with a skin infection, and the host response transcriptome was assessed using a macrophage infection model. The M. shigaense genome comprises 5,207,883 bp, with 67.2% G+C content and 5098 predicted coding genes. Evolutionarily, the bacterium belongs to a cluster in the phylogenetic tree along with three target opportunistic pathogenic strains, namely, M. avium, M. triplex and M. simiae. Potential virulence genes are indeed expressed by M. shigaense under culture conditions. Phenotypically, M. shigaense had similar infection and replication capacities in a macrophage model as the opportunistic species compared to M. tuberculosis. M. shigaense activated NF-κB, TNF, cytokines and chemokines in the host innate immune-related signaling pathways and elicited an early response shared with pathogenic bacilli except M. tuberculosis. M. shigaense upregulated specific host response genes such as TLR7, CCL4 and CXCL5. We performed an integrated and comparative analysis of M. shigaense. Multigroup comparison indicated certain differences with typical pathogenic bacilli in terms of gene features and the macrophage response.

Inference of immune cell composition on the expression profiles of mouse tissue.

Mice are some of the widely used experimental animal models for studying human diseases. Defining the compositions of immune cell populations in various tissues from experimental mouse models is critical to understanding the involvement of immune responses in various physiological and patho-physiological conditions. However, non-lymphoid tissues are normally composed of vast and diverse cellular components, which make it difficult to quantify the relative proportions of immune cell types. Here we report the development of a computational algorithm, ImmuCC, to infer the relative compositions of 25 immune cell types in mouse tissues using microarray-based mRNA expression data. The ImmuCC algorithm showed good performance and robustness in many simulated datasets. Remarkable concordances were observed when ImmuCC was used on three public datasets, one including enriched immune cells, one with normal single positive T cells, and one with leukemia cell samples. To validate the performance of ImmuCC objectively, thorough cross-comparison of ImmuCC predicted compositions and flow cytometry results was done with in-house generated datasets collected from four distinct mouse lymphoid tissues and three different types of tumor tissues. The good correlation and biologically meaningful results demonstrate the broad utility of ImmuCC for assessing immune cell composition in diverse mouse tissues under various conditions.

Recombinant Murine Gamma Herpesvirus 68 Carrying KSHV G Protein-Coupled Receptor Induces Angiogenic Lesions in Mice.

Human gamma herpesviruses, including Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV), are capable of inducing tumors, particularly in in immune-compromised individuals. Due to the stringent host tropism, rodents are resistant to infection by human gamma herpesviruses, creating a significant barrier for the in vivo study of viral genes that contribute to tumorigenesis. The closely-related murine gamma herpesvirus 68 (γHV68) efficiently infects laboratory mouse strains and establishes robust persistent infection without causing apparent disease. Here, we report that a recombinant γHV68 carrying the KSHV G protein-coupled receptor (kGPCR) in place of its murine counterpart induces angiogenic tumors in infected mice. Although viral GPCRs are conserved in all gamma herpesviruses, kGPCR potently activated downstream signaling and induced tumor formation in nude mouse, whereas γHV68 GPCR failed to do so. Recombinant γHV68 carrying kGPCR demonstrated more robust lytic replication ex vivo than wild-type γHV68, although both viruses underwent similar acute and latent infection in vivo. Infection of immunosuppressed mice with γHV68 carrying kGPCR, but not wild-type γHV68, induced tumors in mice that exhibited angiogenic and inflammatory features shared with human Kaposi's sarcoma. Immunohistochemistry staining identified abundant latently-infected cells and a small number of cells supporting lytic replication in tumor tissue. Thus, mouse infection with a recombinant γHV68 carrying kGPCR provides a useful small animal model for tumorigenesis induced by a human gamma herpesvirus gene in the setting of a natural course of infection.

iBIG: an integrative network tool for supporting human disease mechanism studies.

Understanding the mechanism of complex human diseases is a major scientific challenge. Towards this end, we developed a web-based network tool named iBIG (stands for integrative BIoloGy), which incorporates a variety of information on gene interaction and regulation. The generated network can be annotated with various types of information and visualized directly online. In addition to the gene networks based on physical and pathway interactions, networks at a functional level can also be constructed. Furthermore, a supplementary R package is provided to process microarray data and generate a list of important genes to be used as input for iBIG. To demonstrate its usefulness, we collected 54 microarrays on common human diseases including cancer, neurological disorders, infectious diseases and other common diseases. We processed the microarray data with our R package and constructed a network of functional modules perturbed in common human diseases. Networks at the functional level in combination with gene networks may provide new insight into the mechanism of human diseases. iBIG is freely available at http://lei.big.ac.cn/ibig.