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The recent discovery of copper‐mediated and mitochondrion‐dependent cuproptosis has aroused strong interest in harnessing this novel mechanism of cell death for cancer therapy. Here the design of a core‐shell nanoparticle, CuP/Er, for the co‐delivery of copper (Cu) and erastin (Er) to cancer cells for synergistic cuproptosis and ferroptosis is reported. The anti‐Warburg effect of Er sensitizes tumor cells to Cu‐mediated cuproptosis, leading to irreparable mitochondrial damage by depleting glutathione and enhancing lipid peroxidation. CuP/Er induces strong immunogenic cell death, enhances antigen presentation, and upregulates programmed death‐ligand 1 expression. Consequently, CuP/Er promotes proliferation and infiltration of T cells, and when combined with immune checkpoint blockade, effectively reinvigorates T cells to mediate the regression of murine colon adenocarcinoma and triple‐negative breast cancer and prevent tumor metastasis. This study suggests a unique opportunity to synergize cuproptosis and ferroptosis with combination therapy nanoparticles to elicit strong antitumor effects and potentiate current cancer immunotherapies. [ABSTRACT FROM AUTHOR]

Intrinsic immunosuppressive tumor microenvironment (ITM) and insufficient tumor infiltration of T cells severely impede the progress of glioblastoma (GBM) immunotherapy. In this study, it is identify that inhibiting the expression of glucose transporter 1 (GLUT1) can facilitate the prevention of lactate excretion from tumor glycolysis, which significantly alleviates the lactate‐driven ITM by reducing immunosuppressive tumor‐associated macrophages (TAMs) and regulatory T cells (Tregs). Simultaneously, the findings show that the generated inflammatory cytokine IFN‐γ during immune activation aggravates the immune escape by upregulating immune checkpoint programmed death‐ligand 1 (PD‐L1) in tumor cells and TAMs. Therefore, an injectable thermogel loaded with a GLUT1 inhibitor BAY‐876 and a PD‐1/PD‐L1 blocker BMS‐1 (Gel@B‐B) for dual‐regulation of metabolism and immunity of GBM is developed. Consequently, in situ injection of Gel@B‐B significantly delays tumor growth and prolongs the survival of the orthotopic GBM mouse model. By actively exposing tumor antigens to antigen‐presenting cells, the GBM vaccine combined with Gel@B‐B is found to significantly increase the fraction of effector T cells (Th1/CTLs) in the tumor microenvironment, thereby remarkably mitigating tumor recurrence long‐term. This study may provide a promising strategy for GBM immunotherapy. [ABSTRACT FROM AUTHOR]

Summary: Immune checkpoint blocking therapy targeting the PD‐1/PD‐L1 inhibitory signalling pathway has produced encouraging results in the treatment of a variety of cancers. Durvalumab (Imfinzi®) targeting PD‐L1 is currently used for immunotherapy of several tumour malignancies. The Fc region of this IgG1 antibody has been engineered to reduce FcγR interactions with the aim of enhancing blockade of PD‐1/PD‐L1 interactions without the depletion of PD‐L1‐expressing immune cells. Here, we used Nicotiana benthamiana to produce four variants of Durvalumab (DL): wild‐type IgG1 and its 'Fc‐effector‐silent' variant (LALAPG) carrying further modifications to increase antibody half‐life (YTE); IgG4S228P and its variant (PVA) with Fc mutations to decrease binding to FcγRI. In addition, DL variants were produced with two distinct glycosylation profiles: afucosylated and decorated with α1,6‐core fucose. Plant‐derived DL variants were compared to the therapeutic antibody regarding their ability to (i) bind to PD‐L1, (ii) block PD‐1/PD‐L1 inhibitory signalling and (iii) engage with the neonatal Fc receptor (FcRn) and various Fcγ receptors. It was found that plant‐derived DL variants bind to recombinant PD‐L1 and to PD‐L1 expressed in gastrointestinal cancer cells and are able to effectively block its interaction with PD‐1 on T cells, thereby enhancing their activation. Furthermore, we show a positive impact of Fc amino acid mutations and core fucosylation on DL's therapeutic potential. Compared to Imfinzi®, DL‐IgG1 (LALAPG) and DL‐IgG4 (PVA)S228P show lower affinity to CD32B inhibitory receptor which can be therapeutically favourable. Importantly, DL‐IgG1 (LALAPG) also shows enhanced binding to FcRn, a key determinant of serum half‐life of IgGs. [ABSTRACT FROM AUTHOR]

As an essential intracellular immune activation pathway, the cGAS‐STING pathway has attracted broad attention in cancer treatment. However, low bioavailability, nonspecificity, and adverse effects of small molecule STING agonists severely limit their therapeutic efficacy and in vivo application. In this study, a peptide‐based STING agonist is first proposed, and KLA is screened out to activate the cGAS‐STING pathway by promoting mitochondrial DNA (mtDNA) leakage. To precisely activate the cGAS‐STING pathway and block the PD‐1/PD‐L1 pathway, a multi‐stimuli activatable peptide nanodrug (MAPN) is developed for the effective delivery of KLA and PD‐L1 antagonist peptide (CVR). With rational design, MAPN achieved the site‐specific release of KLA and CVR in response to multiple endogenous stimuli, simultaneously activating the cGAS‐STING pathway and blocking PD‐1/PD‐L1 pathway, ultimately initiating robust and durable T cell anti‐tumor immunity with a tumor growth inhibition rate of 78% and extending the median survival time of B16F10 tumor‐bearing mice to 40 days. Overall, antimicrobial peptides, which can promote mtDNA leakage through damaging mitochondrial membranes, may be potential alternatives for small molecule STING agonists and giving a new insight for the design of novel STING agonists. Furthermore, MAPN presents a universal delivery platform for the effective synergy of multiple peptides. [ABSTRACT FROM AUTHOR]

Background: Metastatic castration‐resistant prostate cancer (mCRPC) remains fatal and incurable, despite a variety of treatments that can delay disease progression and prolong life. Immune checkpoint therapy is a promising treatment. However, emerging evidence suggests that exosomal programmed necrosis ligand 1 (PD‐L1) directly binds to PD‐1 on the surface of T cells in the drain lineage lymph nodes or neutralizes administered PD‐L1 antibodies, resulting in poor response to anti‐PD‐L1 therapy in mCRPC. Materials and Methods: Western blotting and immunofluorescence were performed to compare PD‐L1 levels in exosomes derived from different prostate cancer cells. PC3 cells were subcutaneously injected into nude mice, and then ELISA assay was used to detect human specific PD‐L1 in exosomes purified from mouse serum. The function of CD8+ T cells was detected by T cell mediated tumor cell killing assay and FACS analysis. A subcutaneous xenograft model was established using mouse prostate cancer cell RM1, exosomes with or without PD‐L1 were injected every 3 days, and then tumor size and weight were analyzed to evaluate the effect of exosomal PD‐L1. Results: Herein, we found that exosomal‐PD‐L1 was taken up by tumor cells expressing low levels of PD‐L1, thereby protecting them from T‐cell killing. Higher levels of PD‐L1 were detected in exosomes derived from the highly malignant prostate cancer PC3 and DU145 cell lines. Moreover, exosomal PD‐L1 was taken up by the PD‐L1‐low‐expressing LNCaP cell line and inhibited the killing function of CD8‐T cells on tumor cells. The growth rate of RM1‐derived subcutaneous tumors was decreased after knockdown of PD‐L1 in tumor cells, whereas the growth rate recovered following exosomal PD‐L1 tail vein injection. Furthermore, in the serum of mice with PCa subcutaneous tumors, PD‐L1 was mainly present on exosomes. Conclusion: In summary, tumor cells share PD‐L1 synergistically against T cells through exosomes. Inhibition of exosome secretion or prevention of PD‐L1 sorting into exosomes may improve the therapeutic response of prostate tumors to anti‐PD‐L1 therapy. [ABSTRACT FROM AUTHOR]

Blockade of immune checkpoints as a strategy of cancer cells to overcome the immune response has received ample attention in cancer research recently. In particular, expression of PD‐L1 by various cancer cells has become a paradigm in this respect. Delivery of PD‐L1 to its site of action occurs either by local diffusion, or else by transport via small extracellular vesicles (sEVs, commonly referred to as exosomes). Many steps of sEVs formation, their packaging with PD‐L1 and their release into the extracellular space have been studied in detail. The likely dependence of release on Ca2+‐signaling, however, has received little attention. This is surprising, since the intracellular Ca2+‐concentration is known as a prominent regulator of many secretory processes. Here, we report on the roles of three Ca2+‐dependent proteins in regulating release of PD‐L1‐containing sEVs, as well as on the growth of tumors in mouse models. We show that sEVs release in cancer cell lines is Ca2+‐dependent and the knockdown of the gene coding the Ca2+‐channel protein ORAI1 reduces Ca2+‐signals and release of sEVs. Consequently, the T cell response is reinvigorated and tumor progression in mouse models is retarded. Furthermore, analysis of protein expression patterns in samples from human cancer tissue shows that the ORAI1 gene is significantly upregulated. Such upregulation is identified as an unfavorable prognostic factor for survival of patients with non‐small‐cell lung cancer. We show that reduced Ca2+‐signaling after knockdown of ORAI1 gene also compromises the activity of melanophilin and Synaptotagmin‐like protein 2, two proteins, which are important for correct localization of secretory organelles within cancer cells and their transport to sites of exocytosis. Thus, the Ca2+‐channel ORAI1 and Ca2+‐dependent proteins of the secretion pathway emerge as important targets for understanding and manipulating immune checkpoint blockade by PD‐L1. [ABSTRACT FROM AUTHOR]