Anti-CD73 and anti-OX40 immunotherapy coupled with a novel biocompatible enzyme prodrug system for the treatment of recurrent, metastatic ovarian cancer

Identification of Potential Protein Targets in Extracellular Vesicles Isolated from Chemotherapy-Treated Ovarian Cancer Cells

Despite the ongoing clinical trials and the introduction of novel treatments over the past few decades, ovarian cancer remains one of the most fatal malignancies in women worldwide. Platinum- and paclitaxel-based chemotherapy is effective in treating the majority of patients with ovarian cancer. However, more than 70% of patients experience recurrence and eventually develop chemoresistance. To improve clinical outcomes in patients with ovarian cancer, novel technologies must be developed for identifying molecular alterations following drug-based treatment of ovarian cancer. Recently, extracellular vesicles (EVs) have gained prominence as the mediators of tumor progression. In this study, we used mass spectrometry to identify the changes in EV protein signatures due to different chemotherapeutic agents used for treating ovarian cancer. By examining these alterations, we identified the specific protein induction patterns of cisplatin alone, paclitaxel alone, and a combination of cisplatin and paclitaxel. Specifically, we found that drug sensitivity was correlated with the expression levels of ANXA5, CD81, and RAB5C in patients receiving cisplatin with paclitaxel. Our findings suggest that chemotherapy-induced changes in EV protein signatures are crucial for the progression of ovarian cancer.

Integrin Targeting Enhances the Antimelanoma Effect of Annexin V in Mice

Malignant melanoma, an increasingly common form of skin cancer, is a major threat to public health, especially when the disease progresses past skin lesions to the stage of advanced metastasis. Targeted drug development is an effective strategy for the treatment of malignant melanoma. In this work, a new antimelanoma tumor peptide, the lebestatin-annexin V (designated LbtA5) fusion protein, was developed and synthesized by recombinant DNA techniques. As a control, annexin V (designated ANV) was also synthesized by the same method. The fusion protein combines annexin V, which specifically recognizes and binds phosphatidylserine, with the disintegrin lebestatin (lbt), a polypeptide that specifically recognizes and binds integrin α1β1. LbtA5 was successfully prepared with good stability and high purity while retaining the dual biological activity of ANV and lbt. MTT assays demonstrated that both ANV and LbtA5 could reduce the viability of melanoma B16F10 cells, but the activity of the fusion protein LbtA5 was superior to that of ANV. The tumor volume growth was slowed in a mouse xenograft model treated with ANV and LbtA5, and the inhibitory effect of high concentrations of LbtA5 was significantly better than that of the same dose of ANV and was comparable to that of DTIC, a drug used clinically for melanoma treatment. The hematoxylin and eosin (H&E) staining test showed that ANV and LbtA5 had antitumor effects, but LbtA5 showed a stronger ability to induce melanoma necrosis in mice. Immunohistochemical experiments further showed that ANV and LbtA5 may inhibit tumor growth by inhibiting angiogenesis in tumor tissue. Fluorescence labeling experiments showed that the fusion of ANV with lbt enhanced the targeting of LbtA5 to mouse melanoma tumor tissue, and the amount of target protein in tumor tissue was significantly increased. In conclusion, effective coupling of the integrin α1β1-specific recognition molecule lbt confers stronger biological antimelanoma effects of ANV, which may be achieved by the dual effects of effective inhibition of B16F10 melanoma cell viability and inhibition of tumor tissue angiogenesis. The present study describes a new potential strategy for the application of the promising recombinant fusion protein LbtA5 in the treatment of various cancers, including malignant melanoma.

Metabolism of Selenium, Selenocysteine, and Selenoproteins in Ferroptosis in Solid Tumor Cancers

A potential target of precision nutrition in cancer therapeutics is the micronutrient selenium (Se). Se is metabolized and incorporated as the amino acid selenocysteine (Sec) into 25 human selenoproteins, including glutathione peroxidases (GPXs) and thioredoxin reductases (TXNRDs), among others. Both the processes of Se and Sec metabolism for the production of selenoproteins and the action of selenoproteins are utilized by cancer cells from solid tumors as a protective mechanism against oxidative damage and to resist ferroptosis, an iron-dependent cell death mechanism. Protection against ferroptosis in cancer cells requires sustained production of the selenoprotein GPX4, which involves increasing the uptake of Se, potentially activating Se metabolic pathways such as the trans-selenation pathway and the TXNRD1-dependent decomposition of inorganic selenocompounds to sustain GPX4 synthesis. Additionally, endoplasmic reticulum-resident selenoproteins also affect apoptotic responses in the presence of selenocompounds. Selenoproteins may also help cancer cells adapting against increased oxidative damage and the challenges of a modified nutrient metabolism that result from the Warburg switch. Finally, cancer cells may also rewire the selenoprotein hierarchy and use Se-related machinery to prioritize selenoproteins that are essential to the adaptations against ferroptosis and oxidative damage. In this review, we discuss both the evidence and the gaps in knowledge on how cancer cells from solid tumors use Se, Sec, selenoproteins, and the Se-related machinery to promote their survival particularly via resistance to ferroptosis.

Pathobiological functions and clinical implications of annexin dysregulation in human cancers

Annexins are an extensive superfamily of structurally related calcium- and phospholipid-binding proteins, largely conserved and widely distributed among species. Twelve human annexins have been identified, referred to as Annexin A1-13 (A12 remains as of yet unassigned), whose genes are spread throughout the genome on eight different chromosomes. According to their distinct tissue distribution and subcellular localization, annexins have been functionally implicated in a variety of biological processes relevant to both physiological and pathological conditions. Dysregulation of annexin expression patterns and functions has been revealed as a common feature in multiple cancers, thereby emerging as potential biomarkers and molecular targets for clinical application. Nevertheless, translation of this knowledge to the clinic requires in-depth functional and mechanistic characterization of dysregulated annexins for each individual cancer type, since each protein exhibits varying expression levels and phenotypic specificity depending on the tumor types. This review specifically and thoroughly examines the current knowledge on annexin dysfunctions in carcinogenesis. Hence, available data on expression levels, mechanism of action and pathophysiological effects of Annexin A1-13 among different cancers will be dissected, also further discussing future perspectives for potential applications as biomarkers for early diagnosis, prognosis and molecular-targeted therapies. Special attention is devoted to head and neck cancers (HNC), a complex and heterogeneous group of aggressive malignancies, often lately diagnosed, with high mortality, and scarce therapeutic options.

Screening, characterization and anti-cancer application of purified intracellular MGL

L-methionine-γ-lyase (MGL) producing bacterial isolates were screened from soil samples that further characterized as 'Klebsiella oxytoca BLM-1' by biochemical and 16S rDNA sequencing. Intracellular MGL obtained from K. oxytoca BLM-1 by sonication was purified by Octyl-Sepharose and Sephadex G-200 column chromatography. MALDI-TOF-MS analysis of protein band (Mr ~ 63 kDa) confirmed the PLP-dependence and structural similarity with MGL enzyme. Purified MGL (1.1 μg) exhibited the maximum activity in potassium phosphate buffer (80 mM; with L-met 20 mM pH 7.0) at 37 °C. That further enhanced in the presence of NaCl (2 mM), Tween-80 (1.0 %; v/v) and EDTA (5 mM). K_m and V_max for purified MGL by using L-met as substrate was found to be 5.32 mM and 0.386 U/mL/min. The purified MGL showed PLP dependence and the half-life was 365.59 min. The MGL was effective against breast cancer (MCF7), gastric adenocarcinoma and human glioblastoma (U87MG) cancer cell lines with IC₅₀ values of purified MGL 0.041 U/mL, 0.008 U/mL and 0.009 U/mL, respectively. The U87MG, greatly affected by MGL treatment, when cultured in DMEM medium (10 mL) with PLP, homocysteine and 10 % FCS as compared to control/untransformed mouse spleen cells.

Clinical Research on the Mechanisms Underlying Immune Checkpoints and Tumor Metastasis

This study highlights aspects of the latest clinical research conducted on the relationship between immune checkpoints and tumor metastasis. The overview of each immune checkpoint is divided into the following three sections: 1) structure and expression; 2) immune mechanism related to tumor metastasis; and 3) clinical research related to tumor metastasis. This review expands on the immunological mechanisms of 17 immune checkpoints, including TIM-3, CD47, and OX-40L, that mediate tumor metastasis; evidence shows that most of these immune checkpoints are expressed on the surface of T cells, which mainly exert immunomodulatory effects. Additionally, we have summarized the roles of these immune checkpoints in the diagnosis and treatment of metastatic tumors, as these checkpoints are considered common predictors of metastasis in various cancers such as prostate cancer, non-Hodgkin lymphoma, and melanoma. Moreover, certain immune checkpoints can be used in synergy with PD-1 and CTLA-4, along with the implementation of combination therapies such as LIGHT-VTR and anti-PD-1 antibodies. Presently, most monoclonal antibodies generated against immune checkpoints are under investigation as part of ongoing preclinical or clinical trials conducted to evaluate their efficacy and safety to establish a better combination treatment strategy; however, no significant progress has been made regarding monoclonal antibody targeting of CD28, VISTA, or VTCN1. The application of immune checkpoint inhibitors in early stage tumors to prevent tumor metastasis warrants further evidence; the immune-related adverse events should be considered before combination therapy. This review aims to elucidate the mechanisms of immune checkpoint and the clinical progress on their use in metastatic tumors reported over the last 5 years, which may provide insights into the development of novel therapeutic strategies that will assist with the utilization of various immune checkpoint inhibitors.

Generation and characterization of a high-affinity chimeric anti-OX40 antibody with potent antitumor activity

OX40 is a costimulatory molecule that belongs to the tumor necrosis factor receptor (TNFR) superfamily. OX40 agonist-based combinations are emerging as promising candidates for novel cancer immunotherapy. Clinical trials have shown that OX40 agonist antibodies could lead to better results in cancer patients. Using a hybridoma platform and three different types of immunization strategies, namely recombinant protein, DNA, and overexpressing cells, we identified a chimeric anti-OX40 antibody (mAb035-hIgG1 from DNA immunization) that shows excellent binding specificity, and slightly stronger activation of human memory CD4⁺ T cells and similar potent antitumor activity compared with BMS 986178, an anti-OX40 antibody currently being evaluated for the treatment of solid tumors. This paper further systematically investigates the antigen-specific immune response, the number of binders, epitope bins, and functional activities of antibodies among different immunization strategies. Interestingly, we found that different immunization strategies affect the biological activity of monoclonal antibodies.

Annexin Animal Models-From Fundamental Principles to Translational Research

Routine manipulation of the mouse genome has become a landmark in biomedical research. Traits that are only associated with advanced developmental stages can now be investigated within a living organism, and the in vivo analysis of corresponding phenotypes and functions advances the translation into the clinical setting. The annexins, a family of closely related calcium (Ca²⁺)- and lipid-binding proteins, are found at various intra- and extracellular locations, and interact with a broad range of membrane lipids and proteins. Their impacts on cellular functions has been extensively assessed in vitro, yet annexin-deficient mouse models generally develop normally and do not display obvious phenotypes. Only in recent years, studies examining genetically modified annexin mouse models which were exposed to stress conditions mimicking human disease often revealed striking phenotypes. This review is the first comprehensive overview of annexin-related research using animal models and their exciting future use for relevant issues in biology and experimental medicine.

Expression and Clinical Significance of OX40 and OX40L mRNA in Hepatocellular Carcinoma

In a retrospective study, the expression of mRNA of membrane receptor OX40 and its ligand OX40L in liver tissues was analyzed in 34 patients with hepatocellular carcinoma in order to assess their clinical implications and prognostic value. Expression of mRNA was analyzed by reverse transcription PCR and TaqMan probes. Expression of OX40 mRNA was significantly higher in tumor specimens in paired comparison with the samples of adjacent non-tumor tissue or normal liver tissue of control patients. In contrast, expression of OX40L mRNA was lower in tumor tissue in paired comparison with the samples of adjacent non-tumor tissue or normal liver tissue. The clinical and pathological analysis showed that expression of OX40 mRNA significantly correlated with the degree of tumor differentiation; there was an insignificant decreasing trend in the length of recurrence-free period. It was hypothesized that microenvironment of hepatocellular carcinoma can induce immunosuppression due to dysregulation of the expression of OX40 and OX40L in tumor tissue, which promotes tumor growth.

CD137 agonist-based combination immunotherapy enhances activated, effector memory T cells and prolongs survival in pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma(PDAC) is resistant to the PD-1/PD-L1 blockade therapy. Previously, the combination of PD-1 blockade and vaccine therapy was shown to have a modest antitumor activity in murine models of PDAC. We used a murine syngeneic model of metastatic PDAC to identify, among multiple T cell modulators tested, which therapeutic agents in combination with the GVAX cancer vaccine and an anti-PD-1 antagonist antibody(αPD-1) are able to improve the survival. We found that an anti-CD137 agonist antibody(αCD137) most significantly improved survival in the mouse PDAC model. Moreover, αPD-1 and αCD137 together in combination with vaccine therapy more significantly increased the expression of costimulatory molecules CD137 and OX40 on CD4+PD-1+ and CD8+PD-1+ T cells comparing to αPD-1 or αCD137, respectively, suggesting that T cell activation within PDACs were enhanced by a synergy of αCD137 and αPD-1. On another hand, αCD137 treatment led to an increase in effector memory T cells independent of αPD-1. Although αCD137 does not increase the cytotoxic effector T cell function, the addition of αCD137 to GVAX+αPD-1 increased expression of IFNγ in EOMES + exhausted tumor-infiltrating T cells. Taken together, this preclinical study established the mechanism of targeting CD137 to enhance effector memory and activated T cells in PDAC. Immunohistochemistry analysis of resected human PDACs following the neo-adjuvant GVAX treatment showed increased levels of CD8⁺ T cells in those with high levels of CD137 expression, supporting an ongoing clinical trial of testing CD137 as a potential target in treating PDACs that are inflamed with T cells by vaccine therapy.

Efficacy of Combination Therapy with Linalool and Doxorubicin Encapsulated by Liposomes as a Two-in-One Hybrid Carrier System for Epithelial Ovarian Carcinoma

BACKGROUND

Epithelial ovarian cancer (EOC) is a fatal gynecologic malignancy that is usually treated with chemotherapy after surgery. However, patients who receive chemotherapy experience severe side effects because of the inherent toxicity and high dose of chemotherapeutics. To overcome these issues, we suggest a combination therapeutic strategy using liposomes encapsulating linalool nanoemulsions (LN-NEs) and doxorubicin (DOX), a chemotherapeutic drug, to increase their synergistic antitumor efficacy and reduce the incidence of side effects from chemotherapeutics for EOC.

METHODS

The physical properties of LN-NE-DOX-liposomes were characterized by light scattering with a particle size analyzer. Cell viability was determined by MTT assay. Therapeutic efficacy was evaluated in a mouse HeyA8 EOC tumor model of ovarian carcinoma. Additionally, biochemical toxicity was analyzed for levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and blood urea nitrogen (BUN) using BALB/c nude mice.

RESULTS

The size of the liposomes encapsulating LN-NEs and DOX (LN-NE-DOX-liposomes) was 267.0 ± 4.6 nm, with a loading efficiency of 55.1 ± 3.1% and 27.2 ± 0.9% for linalool and DOX, respectively. Cell viability after treatment with LN-NE-DOX-liposomes was significantly decreased compared to that of cells treated with DOX liposomes, and apoptosis was significantly increased. Additionally, LN-NE-DOX-liposomes significantly inhibited HeyA8 EOC tumor growth compared to that of the control (p < 0.01) and DOX-liposome-treated groups (p < 0.05), while decreasing cell proliferation (Ki67) and microvessel density (CD31), and promoting apoptosis (caspase-3) compared to the control (p < 0.05). Moreover, the liposomal formulations induced no significant differences in biochemical toxicity (AST, ALT, and BUN) compared to healthy control mice, indicating that the liposomal formulations showed no overt toxicity in mice.

CONCLUSION

This study demonstrates that the production of LN-NE-DOX-liposomes is a pivotal approach for EOC treatment, suggesting a novel combination therapeutic strategy.

Anionic phospholipid expression as a molecular target in Listeria monocytogenes and Escherichia coli

This study validates bacterial anionic phospholipids (APs) as a putative molecular target in a novel antibiotic treatment against the Gram-positive bacterium Listeria monocytogenes and the Gram-negative bacterium Escherichia coli. Bacterial AP expression was targeted with its associated protein-ligand partner, annexin A5 (ANXA5). This protein was functionalised with the covalent addition of the antibiotic ampicillin (AMP) and separately with the antibiotic moxifloxacin (MOX). Functionalised ANXA5 serves as a delivery vehicle, directing the antibiotic to bacterial AP expression. The results presented here suggest that this ANXA5-AMP bioconjugate participates in a positive feedback loop where APs, the target of the delivery vehicle ANXA5, are upregulated by the chemotherapeutic payload of the bioconjugate. Importantly, the ANXA5 delivery vehicle is non-toxic to bacterial cells by itself and neither is the ANXA5-antibiotic bioconjugate toxic to human vascular endothelial cells. As measured by the IC₅₀, conjugation to ANXA5 resulted in increasing the antibiotic activity of AMP against L. monocytogenes and E. coli by more than 4 and 3 orders of magnitude, respectively, compared with free AMP, whilst the activity of MOX against L. monocytogenes is increased by 4 orders of magnitude. Given the conservation of AP expression in pathologies such as oncogenesis and other bacterial/viral/parasitic infections, we hypothesise that a therapeutic modality targeting AP expression may be a viable chemotherapeutic strategy in many infectious diseases.

New pathways in immune stimulation: targeting OX40

Immune checkpoint blockers (ICB) reinvigorate the immune system by removing the molecular brakes responsible for the scarce activity of immune phenotypes against malignant cells. After having proven their remarkable role as monotherapy, combinations of anti-Programmed cell death 1 (PD-1)/Programmed death-ligand 1 (PD-L1) agents with cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) antibodies, chemotherapy and/or anti-angiogenic compounds provide unprecedented results and durable responses across a variety of tumour types. Nevertheless, the main drawbacks of ICB are represented by primary and acquired resistance, translating into disease progression, as well as by immune-related toxicities. In this sense, novel strategies to foster the immune system through its direct stimulation are being tested in order to provide additional clinical improvements in patients with cancer. In this scenario, the co-stimulatory molecule OX40 (CD134) belongs to the next generation of immune therapeutic targets. Preliminary results of early clinical trials evaluating OX40 stimulation by means of different agents are encouraging. Here we review the rationale of OX40 targeting, highlighting the combination of OX40-directed therapies with different anticancer agents as a potential strategy to foster the immune system against malignant phenotypes.

OX40 (CD134) and OX40 ligand, important immune checkpoints in cancer

Immunotherapy has shown promising results in cancer treatment. Research shows that most patients might be resistant to these therapies. So, new immune therapies are needed. OX40 (CD134) and OX40 ligand (OX40L), costimulatory molecules, express on different types of immune cells. The interaction between OX40 and OX40L (OX40/OX40L) induces the expansion and proliferation of T cells and decreases the immunosuppression of regulatory T (Treg) cells to enhance the immune response to the specific antigen. For the important role OX40 takes in the process of immunity, many clinical trials are focusing on OX40 to find out whether it may have active effects in clinical cancer treatment. The results of clinical trials are still not enough. So, we reviewed the OX40 and its ligand (OX40L) function in cancer, clinical trials with OX40/OX40L and the correlation between OX40/OX40L and other immune checkpoints to add more ideas to tumor feasible treatment.

Adenosine Blockage in Tumor Microenvironment and Improvement of Cancer Immunotherapy

Immunotherapy has been introduced into cancer treatment methods, but different problems have restricted the efficacy of these protocols in clinical trials such as the presence of various immunomodulatory factors in the tumor microenvironment. Adenosine is an immunosuppressive metabolite produced by the tumor to promote growth, invasion, metastasis, and immune evasion. Many studies about adenosine and its metabolism in cancer have heightened interest in pursuing this treatment approach. It seems that targeting the adenosine pathway in combination with immunotherapy may lead to efficient antitumor response. In this review, we provide information on the roles of both adenosine and CD73 in the immune system and tumor development. We also describe recent studies about combination therapy with both purinergic inhibitors and other immunotherapeutic methods.

OX40 and OX40L protein expression of tumor infiltrating lymphocytes in non-small cell lung cancer and its role in clinical outcome and relationships with other immune biomarkers

Background

Anti-tumoral immunotherapy of anti-program death-1/program death-ligand 1 (PD-1/PD-L1) immune checkpoint therapy demonstrated promising efficacy and tolerability in patients with lung cancer. Apart from inhibitory checkpoints, OX40, the co-stimulatory receptor related to T cell priming and proliferation, was valued identically. In this study, the relationship between OX40/OX40L expressed on tumor infiltrating lymphocytes (TILs), PD-1/PD-L1 and other immunological factors, as well as its role serving as the potential prognostic biomarker, were analyzed in NSCLC.

Methods

We investigated the relationship between OX40/OX40L, PD-1/PD-L1 and TILs in surgical samples from 139 patients with NSCLC by immunohistochemistry (IHC). Factors related to OX40/OX40L expression were analyzed by logistic regression and multi-linear regression. Cox analysis was also performed to find the influencing factors. Survival analysis was conducted in order to testify its role in predicting patients' prognosis.

Results

The TILs OX40, OX40L expression were negatively correlated with the PD-1/PD-L1 expression, respectively. PD-1 expression was negatively correlated with the TILs OX40 expression [R=0.250, (P=0.003)], it was also negatively correlated with the TILs OX40L expression [R=0.386, (P=0.0001)]. PD-1 expression was positively correlated with TILs grades and negatively correlated with the TILs OX40L expression in multiple linear model [R=0.531, (X1, 95% CI: 3.552-8.176, P=0.0001; X2, 95% CI: 0.216-0.683), (P=0.0001)]. The expression of TILs OX40 varied significantly among tumor OX40 and OX40L, PD-1, PD-L1, TILs and pathology types. Tumor OX40L expression, TILs OX40L expression, PD-1 expression, PD-L1 expression and TILs were considered as risk factors for TILs OX40 expression. The staging and TILs OX40L were considered as risk factors for overall survival (OS) while stage and gender were risk factors for recurrence-free survival (RFS). The low-expression of OX40 was related to longer RFS, OS and better prognosis.

Conclusions

OX40 plays a pivotal role in NSCLC, which was closely correlated with immunological factors, RFS and prognosis.

Immunometabolic Dysfunction of Natural Killer Cells Mediated by the Hypoxia-CD73 Axis in Solid Tumors

NK cell infiltration into solid tumors is often low and is largely represented by the poorly-cytotoxic CD56^bright subset. Numerous studies have demonstrated that CD73, overexpressed under conditions of hypoxia, is involved in a variety of physiological processes, while its overexpression has been correlated with tumor invasiveness, metastasis and poorer patient survival in many cancers. Hypoxia itself favors aggressive glycolytic fueling of cancer cells, in turn driving reprogramming of NK cell metabolism. In addition, the hypoxia-driven activity of CD73 immunometabolically impairs NK cells in tumors, due to its catalytic role in the generation of the highly immunosuppressive metabolite adenosine. Adenosinergic signaling was shown to alter NK cell metabolic programs, leading to tumor-promoting environments characterized by NK cell dysfunction. Despite the demonstrated role of NK cell responses in the context of CD73 targeting, the engagement of NK cells in the setting of hypoxia/CD73 signaling has not been extensively studied or exploited. Here, we discuss available evidence on the role of hypoxic signaling on CD73-mediated activity, and how this relates to the immunometabolic responses of NK cells, with a particular focus on the therapeutic targeting of these pathways.