InVivoSIM anti-human PD-L1 (Atezolizumab Biosimilar)

Programmed cell death-1 (PD-1) is a co-inhibitory receptor expressed on T cells that dampens TCR and CD28 signaling in the immunological synapse. PD-1 is significantly upregulated on T cells in the tumor microenvironment, where it promotes exhaustion in the context of chronic antigen restimulation. Exhaustion renders T cells hyporesponsive and ineffectual, but potentially resistant to restimulation-induced cell death (RICD). Restimulation-induced cell death (RICD) is a critical propriocidal apoptosis program triggered in activated T cells upon robust TCR re-engagement, which serves to constrain effector T cell expansion and longevity to prevent collateral tissue damage. While the checkpoint function of PD-1 has profound implications for cancer immunotherapy, the role of PD-1 in regulating newly activated T cells remains unclear. We hypothesized that PD-1 attenuates RICD sensitivity in human effector T cells by modulating TCR signal strength. Here we show that transient upregulation of PD-1 helps to protect clonally expanding human CD4+ and CD8 + T cells from premature RICD, with only moderate protection noted in terminally-differentiated, PD-1lo effector CD8 + T cells. Restimulation of T cells with beads containing PD-L1 results in significant apoptosis resistance, dependent on PD-L1 dosage and the proximity of PD-L1 to the TCR and CD28. Interestingly, PD-L1 demonstrated a more significant RICD rescue with CD28 co-ligation as opposed to TCR engagement alone, suggesting PD-1 signaling targets both signaling pathways in this context. Furthermore, biochemical/proteomic data suggest PD-1 modulates proximal signaling downstream of both TCR and CD28 and influences the expression of specific pro/anti-apoptotic proteins that govern RICD sensitivity. Despite the original assumption of PD-1 as a programmed death-inducing protein, our research reveals that homeostatic expression of PD-1 in clonally expanding T cells confers RICD resistance that promotes T cell survival and persistence. These findings present significant implications for understanding how blocking or engaging the PD-L1:PD-1 signaling axis may influence apoptosis sensitivity in both normal and exhausted T cells to alter adaptive immune responses.

Immunologically "cold" tumors, characterized by low immune cells infiltration, represent a significant obstacle to the success of immune checkpoint therapy. Intestinal microbiome therapy has emerged as a potential strategy to overcome this challenge by reprogramming the immune microenvironment. However, its clinical application is constrained by unresolved safety concerns. To address these challenges, we fused Escherichia coli-secreted outer membrane vesicle (OMV) with the macrophage membrane vector (RV) to construct hybrid nanovesicle (ROMV) and encapsulated the bacterial metabolite trimethylamine N-oxide (TMAO), forming ROMV/TMAO. ROMV/TMAO mimicked the beneficial functions of intestinal probiotics by leveraging the immunomodulatory properties of OMV and TMAO, combined with the tumor-homing capabilities of RV. In human lung cancer organoids and multiple tumor models, selective tumor targeting and accumulation of ROMV/TMAO facilitated M1 polarization of tumor-associated macrophages and enhanced CD8+ T lymphocyte infiltration, ultimately inhibiting tumor growth. When combined with ROMV/TMAO, the immune checkpoint inhibitor α-PD-L1 exhibited superior antitumor efficacy than monotherapy. This study introduces a probiotic-inspired nanotherapeutic strategy for augmenting immune checkpoint therapy outcomes while addressing microbiome therapy safety challenges.

Hypoxia is a crucial characteristic of hepatocellular carcinoma (HCC) and contributes to immune resistance by upregulating PD-L1 and recruiting immunosuppressive cells. However, the molecular mechanisms of hypoxia-induced immunotherapy resistance are still unclear. The hypoxia-related immunotherapy response (IRH) genes were identified and used to develop a hypoxia risk score model to predict patient survival. The model was validated using GSE233802 and EGAD00001008128 datasets. The hypoxia risk score model including NOXA effectively stratified patients based on risk and demonstrated excellent survival predictive ability (p = 0.0236). A hypoxia-induced drug-resistant (HepG2-R) cell line was established by co-culturing HepG2 cells with Jurkat T cells under CoCl2-induced hypoxia and PD-L1 inhibitor administration. Prolonged exposure to hypoxia (48 h) in HepG2 cells significantly led to the increased hypoxia risk score (p < 0.02). The establishment of the HepG2-R cell line showed that prolonged hypoxia reduced cancer cell apoptosis, which implies potential treatment resistance. The effect of NOXA knockdown on the apoptosis of HepG2-R cells under the same co-culture conditions was examined. Under hypoxia and PD-L1 inhibitor treatment, NOXA knockdown increased the survival rate of HepG2-R cells and reduced early and late apoptosis. This indicates that NOXA plays a crucial role in apoptosis regulation and immune response in hypoxic tumors. NOXA knockdown significantly reduces apoptosis in immunotherapy-resistant cells induced by hypoxia. These findings provide important evidence that targeting NOXA may enhance immunotherapy efficacy and help overcome treatment resistance in HCC, highlighting its potential as a therapeutic target.

This study aimed to investigate the role of kynurenine in Colorectal Cancer (CRC) and the underlying mechanism.

Disrupting the interaction between tumor-cell surface PD-L1 and T cell membrane PD-1 can elicit durable clinical responses. However, only about 10% of ovarian cancer patients respond to PD-1/PD-L1 blockade. Here, we show that PD-L1 expression in ovarian cancer-patient tumors is predominantly intracellular. Notably, PARP inhibitor treatment highly increased intracellular PD-L1 accumulation in both ovarian cancer-patient tumor samples and cell lines. We investigated whether intracellular PD-L1 might play a critical role in ovarian cancer progression. Mutating the PD-L1 acetylation site in PEO1 and ID8Brca1-/- ovarian cancer cells significantly decreased PD-L1 levels and impaired colony formation, which was accompanied by cell cycle G2/M arrest and apoptosis induction. PEO1 and ID8Brca1-/- tumors with PD-L1 acetylation site mutation also exhibited significantly reduced growth in mice. Furthermore, targeting intracellular PD-L1 with a cell-penetrating antibody effectively decreased ovarian tumor-cell intracellular PD-L1 level and induced tumor-cell growth arrest and apoptosis, as well as enhanced DNA damage and STING activation, both in vitro and in vivo. In conclusion, we have shown the critical role of intracellular PD-L1 in ovarian cancer progression.

Hepatitis B virus (HBV) infection generally elicits weak type-I interferon (IFN) immune response in hepatocytes, covering the regulatory effect of IFN-stimulated genes. In this study, low level of IFN-stimulated gene 12a (ISG12a) predicted malignant transformation and poor prognosis of HBV-associated hepatocellular carcinoma (HCC), whereas high level of ISG12a indicated active NK cell phenotypes. ISG12a interacts with TRIM21 to inhibit the phosphorylation activation of protein kinase B (PKB, also known as AKT) and β-catenin, suppressing PD-L1 expression to block PD-1/PD-L1 signaling, thereby enhancing the anticancer effect of NK cells. The suppression of PD-1-deficient NK-92 cells on HBV-associated tumors was independent of ISG12a expression, whereas the anticancer effect of PD-1-expressed NK-92 cells on HBV-associated tumors was enhanced by ISG12a and treatments of atezolizumab and nivolumab. Thus, tumor intrinsic ISG12a promotes the anticancer effect of NK cells by regulating PD-1/PD-L1 signaling, presenting the significant role of innate immunity in defending against HBV-associated HCC.