Next-generation anti-PD-L1/IL-15 immunocytokine elicits superior antitumor immunity in cold tumors with minimal toxicity.

The clinical applications of immunocytokines are severely restricted by dose-limiting toxicities. To address this challenge, here we propose a next-generation immunocytokine concept involving the design of LH05, a tumor-conditional anti-PD-L1/interleukin-15 (IL-15) prodrug. LH05 innovatively masks IL-15 with steric hindrance, mitigating the "cytokine sink" effect of IL-15 and reducing systemic toxicities associated with wild-type anti-PD-L1/IL-15. Moreover, upon specific proteolytic cleavage within the tumor microenvironment, LH05 releases an active IL-15 superagonist, exerting potent antitumor effects. Mechanistically, the antitumor efficacy of LH05 depends on the increased infiltration of CD8+ T and natural killer cells by stimulating the chemokines CXCL9 and CXCL10, thereby converting cold tumors into hot tumors. Additionally, the tumor-conditional anti-PD-L1/IL-15 can synergize with an oncolytic virus or checkpoint blockade in advanced and metastatic tumor models. Our findings provide a compelling proof of concept for the development of next-generation immunocytokines, contributing significantly to current knowledge and strategies of immunotherapy.

Universal chimeric Fcγ receptor T cells with appropriate affinity for IgG1 antibody exhibit optimal antitumor efficacy.

Developing universal CARs with improved flexible targeting and controllable activities is urgently needed. While several studies have suggested the potential of CD16a in tandem with monoclonal antibodies to construct universal CAR-T cells, the weak affinity between them is one of the limiting factors for efficacy. Herein, we systematically investigated the impact of Fcγ receptor (FcγR) affinity on CAR-T cells properties by constructing universal CARs using Fcγ receptors with different affinities for IgG1 antibodies, namely CD16a, CD32a, and CD64. We demonstrated that the activities of these universal CAR-T cells on tumor cells could be redirected and regulated by IgG1 antibodies. In xenografted mice, 64CAR chimeric Jurkat cells with the highest affinity showed significant antitumor effects in combination with herceptin in the HER2 low expression U251 MG model. However, in the CD20 high expression Raji model, 64CAR caused excessive activation of CAR-T cells, which resulted in cytokine release syndrome (CRS) and the decline of antitumor activity, and 32CAR with a moderate affinity brought the best efficacy. Our work extended the knowledge about FcγR-based universal CAR-T cells and suggested that only the FcγRCAR with an appropriate affinity can offer the optimal antitumor advantages of CAR-T cells.

Oxidation and reduction analysis of therapeutic recombinant human interleukin-15 by HPLC and LC-MS.

Being an important immune stimulant of T lymphocytes and NK cells, the recombinant human interleukin-15 (rhIL-15) has been extensively researched in tumor immunotherapy or as a vaccine adjuvant. However, the rhIL-15 manufacturing level lags far behind its growing clinical demand due to the lack of efficient and exact analysis methodologies to characterize the trace by-products, typically redox and deamidation. In order to improve the production and quality control of rhIL-15, here we developed an expanded resolution reverse-phase high-performance liquid chromatography (ExRP-HPLC) approach to quickly and accurately analyze the oxidation and reduction by-products of rhIL-15, which may appear during the purification processes. Firstly, we developed RP-HPLC methods which can separate rhIL-15 fractions with different levels of oxidization or reduction, respectively, and the redox status of each peak was then determined by measuring the intact mass with a high-resolution mass spectrometer (UPLC-MS). To further clarify the complex pattern of oxidization of specific residues, the peaks with various oxidation levels were digested into pieces for peptide mapping to pinpoint the exact changes of oxygen and hydrogen atoms in the rhIL-15 by-products. In addition, we performed the ExRP-HPLC and UPLC-MS analysis of partially deamidated rhIL-15 to characterize their oxidation and reduction. Our work is the first in-depth characterization of the redox by-products of rhIL-15, even for deamidated impurities. The ExRP-HPLC method we reported can facilitate the rapid and accurate quality analysis of rhIL-15, which is substantially helpful for streamlining the industrial manufacturing of rhIL-15 to better meet the demands of clinical applications. KEYPOINTS: • The oxidization and reduction rhIL-15 by-products were characterized for the first time. • The changes of oxygen and hydrogen atoms in rhIL-15 redox by-products were accurately determined by UPLC-MS. • Oxidation and reduction by-products of deamidated rhIL-15 were further analyzed.

Ferroptosis-related NFE2L2 and NOX4 Genes are Potential Risk Prognostic Biomarkers and Correlated with Immunogenic Features in Glioma.

Ferroptosis is a newfound mode of regulated cell death that may have potential to associate with prognostic or diagnostic factors in glioma. In this research, 5 genes related to glioma were screened through the FerrDb database, and we analyzed the combination between genes and glioma of survival and prognosis via TCGA, GEPIA, TIMER, and other databases. Survival curve and prognostic analysis showed that the overexpression of NFE2L2 and NOX4, respectively, has a remarkable link with a worse prognosis in glioma. Then, the association between the expression of the two genes and tumor-infiltrating immune cells level was explored based on the GSCA, and the immunity of NFE2L2 and NOX4 based on the TISIDB database was also investigated. In glioma, especially GBM, there is a strong association between gene expression and immune infiltration, even in macrophages, nTreg, and Th2 cells, which play immunosuppressive functions in TME. In conclusion, these results indicate that NFE2L2 and NOX4 could be risk prognosis biomarkers in glioma, and they bound up with immune infiltration and tumor immunity in tumorigenesis.

A novel anti-PD-L1/IL-15 immunocytokine overcomes resistance to PD-L1 blockade and elicits potent antitumor immunity.

Despite the demonstrated immense potential of immune checkpoint inhibitors in various types of cancers, only a minority of patients respond to these therapies. Immunocytokines designed to deliver an immune-activating cytokine directly to the immunosuppressive tumor microenvironment (TME) and block the immune checkpoint simultaneously may provide a strategic advantage over the combination of two single agents. To increase the response rate to checkpoint blockade, in this study, we developed a novel immunocytokine (LH01) composed of the antibody against programmed death-ligand 1 (PD-L1) fused to interleukin (IL)-15 receptor alpha-sushi domain/IL-15 complex. We demonstrate that LH01 efficiently binds mouse or human PD-L1 and maintains IL-15 stimulatory activity. In syngeneic mouse models, LH01 showed improved antitumor efficacy and safety versus anti-PD-L1 plus LH02 (Fc-sushi-IL15) combination and overcame resistance to anti-PD-L1 treatment. Mechanistically, the dual anti-immunosuppressive function of LH01 activated both the innate and adaptive immune responses and induced a favorable and immunostimulatory TME. Furthermore, combination therapy with LH01 and bevacizumab exerts synergistic antitumor effects in an HT29 colorectal xenograft model. Collectively, our results provide supporting evidence that fusion of anti-PD-L1 and IL-15 might be a potent strategy to treat patients with cold tumors or resistance to checkpoint blockade.

A homodimeric IL-15 superagonist F4RLI with easy preparation, improved half-life, and potent antitumor activities.

Interleukin-15 (IL-15) is a promising candidate for cancer immunotherapy due to its potent immune-activating effects. There are several IL-15 molecules currently in clinical trials but facing shortages of poor half-life, circulation instability, or complicated production and quality control processes. The aim of this study is to design a novel IL-15 superagonist to set out the above difficulties, and we constructed F4RLI consisting of the GS-linker spaced IgG4 Fc fragment, soluble IL-15 Rα (sIL-15Rα), and IL-15(N72D). Using a single plasmid transient transfection in HEK293E cells, the matured F4RLI was secreted in the form of homodimer and got purified by an easy step of protein A affinity chromatography. The F4RLI product can significantly stimulate the proliferation of human CD3+CD8+ T cells and NK cells in vitro. Meanwhile, F4RLI greatly extended the half-life and prolonged the exposure of IL-15 in mice nearly by 28- and 200-fold, respectively, in comparison with that of the IL-15 monomer. In vivo, F4RLI vastly expanded mouse splenic CD8+ T lymphocytes, illustrating its potential in tumor immunotherapy. Further studies showed that the combination of F4RLI with the immune checkpoint blocker atezolizumab played a synergistic effect in treating MC38 mouse tumor by increasing the percentage of CD8+ T cells in tumor tissue. Moreover, the combination therapy of F4RLI with the angiogenesis inhibitor bevacizumab resulted in significant tumor growth suppression in a xenograft human HT-29 mouse model. Overall, our results demonstrate a homodimeric IL-15 superagonist F4RLI with advances in manufacturing processes and biopharmaceutical applications for cancer immunotherapy. KEY POINTS: • The homodimeric structure of F4RLI facilitates its easy production processes and quality control. • The fusion with Fc and sIL-15Rα extends the plasma half-life of IL-15 by about 28-fold. • F4RLI can play synergistic antitumor activity with the PD-1/PD-L1 checkpoint inhibitor or angiogenesis inhibitor.

SHTXTHHly, an extracellular secretion platform for the preparation of bioactive peptides and proteins in Escherichia coli.

BACKGROUND: In previous work, we developed an E. coli extracellular secretion platform XTHHly based on the hemolysin A secretion system. It can produce bioactive peptides with simple purification procedures. However, the wider application of this platform is limited by poor secretion efficiency. RESULTS: In this study, we first discovered a positive correlation between the isoelectric point (pI) value of the target protein and the secretion level of the XTHHly system. Given the extremely high secretion level of S tag, we fused it at the N-terminus and created a novel SHTXTHHly system. The SHTXTHHly system significantly increased the secretion levels of antimicrobial peptides (PEW300, LL37, and Aurein 1.2) with full bioactivities, suggesting its excellent capacity for secretory production of bioactive peptides. Furthermore, RGDS, IL-15, and alcohol dehydrogenase were successfully secreted, and their bioactivities were largely maintained in the fusion proteins, indicating the potential applications of the novel system for the rapid determination of protein bioactivities. Finally, using the SHTXTHHly system, we produced the monomeric Fc, which showed a high affinity for Fcγ Receptor I and mediated the antibody-dependent immunological effects of immune cells, demonstrating its potential applications in immunotherapies. CONCLUSIONS: The SHTXTHHly system described here facilitates the secretory production of various types of proteins in E. coli. In comparison to previously reported expression systems, our work enlightens an efficient and cost-effective way to evaluate the bioactivities of target proteins or produce them.

Lycium barbarum polysaccharide protects against osteonecrosis of femoral head via regulating Runx2 expression.

BACKGROUND: Osteonecrosis of femoral head (ONFH) is a pathological state caused by lack of blood supply in femoral head. This study aimed to explore the function of Lycium barbarum polysaccharide (LBP), an antioxidant agent extracted from L. barbarum, on ONFH. METHODS: Osteonecrosis rat model was generated using lipopolysaccharide (LPS) and methylprednisolone followed by examination of body weight, blood glucose, morphology, and BMSC osteoblast differentiation. The effect and underlying mechanism of LBP on the proliferation, apoptosis, and osteoblast differentiation of BMSC were determined with or without LPS or hypoxia treatment using CCK-8. Alizarin Red S staining, flow cytometry, and western blot, respectively. RESULT: LBP could protect against glucocorticoid-induced ONFH in rats, resulting in improved sparse trabecular bone, empty lacunae and bone cell coagulation. Moreover, LBP promoted the proliferation and osteoblast differentiation of bone mesenchymal-derived stem cells (BMSCs) in a dose-dependent manner. Furthermore, LBP enhanced osteoblast differentiation of BMSCs under hypoxia condition. Mechanistically, we found that LBP treatment enhanced Runx2 and ALP expression in BMSCs. LBP restored the expression of Runx2 and ALP under hypoxia, suggesting that LBP might be involved in regulating Runx2/ALP expression and contributed to osteoblast differentiation. Knockdown of Runx2 significantly inhibited BMSCs proliferation, while LBP treatment did not rescue the osteoblast differentiation ability of BMSCs with Runx2 knockdown. CONCLUSION: Our findings suggested that LBP protects against ONFH via regulating Runx2 expression, which could be utilized to treat patients suffering ONFH.