Therapeutic effect of interleukin 12 on mouse haemangiosarcomas is not associated with an increased anti-tumour cytotoxic T-lymphocyte activity

Cancer immunotherapy with enveloped self-amplifying mRNA CARG-2020 that modulates IL-12, IL-17 and PD-L1 pathways to prevent tumor recurrence

Targeting multiple immune mechanisms may overcome therapy resistance and further improve cancer immunotherapy for humans. Here, we describe the application of virus-like vesicles (VLV) for delivery of three immunomodulators alone and in combination, as a promising approach for cancer immunotherapy. VLV vectors were designed to deliver single chain interleukin (IL)-12, short-hairpin RNA (shRNA) targeting programmed death ligand 1 (PD-L1), and a dominant-negative form of IL-17 receptor A (dn-IL17RA) as a single payload or as a combination payload. Intralesional delivery of the VLV vector expressing IL-12 alone, as well as the trivalent vector (designated CARG-2020) eradicated large established tumors. However, only CARG-2020 prevented tumor recurrence and provided long-term survival benefit to the tumor-bearing mice, indicating a benefit of the combined immunomodulation. The abscopal effects of CARG-2020 on the non-injected contralateral tumors, as well as protection from the tumor cell re-challenge, suggest immune-mediated mechanism of protection and establishment of immunological memory. Mechanistically, CARG-2020 potently activates Th1 immune mechanisms and inhibits expression of genes related to T cell exhaustion and cancer-promoting inflammation. The ability of CARG-2020 to prevent tumor recurrence and to provide survival benefit makes it a promising candidate for its development for human cancer immunotherapy.

Advances in engineering and delivery strategies for cytokine immunotherapy

INTRODUCTION

Cytokine immunotherapy is a growing field for the treatment of cancer, infectious disease, autoimmunity, and other ailments. Therapeutic cytokines are a class of secreted, small proteins that play a pivotal role in regulating the innate and adaptive immune system by provoking or mitigating immune responses. In the clinic, cytokines are frequently combined with other treatments, such as small molecules and monoclonal antibodies. However, the clinical translation of cytokine therapies is hindered by their short half-life, pleiotropic nature, and off-target effects, which cause diminished efficacy and severe systemic toxicity. Such toxicity limits dosage, thus resulting in suboptimal doses. Accordingly, numerous efforts have been devoted to exploring strategies to promote cytokine therapies by improving their tissue specificity and pharmacokinetics.

AREAS COVERED

Preclinical and clinical research into bioengineering and delivery strategies for cytokines, consisting of bioconjugation, fusion proteins, nanoparticles, and scaffold-based systems.

EXPERT OPINION

These approaches pave the way for the development of next-generation cytokine treatments with greater clinical benefit and reduced toxicity, circumventing such issues currently associated with cytokine therapy.

Chemopreventive and anti-tumor potential of vitamin E in preclinical breast cancer studies: A systematic review

BACKGROUND

Vitamin E has been investigated for its antitumor potential, including the ability to change cancer gene pathways as well as promote antioxidant and pro-oxidant activity.

OBJECTIVE

Therefore, this systematic review aimed to evaluate antitumor and chemopreventive activity of different vitamin E isoforms (tocopherols and tocotrienols) through in vitro and in vivo studies.

METHOD

The systematic review was registered in PROSPERO (No. CRD4202126207) and the search was carried out in four electronic databases (PubMed, Science Direct, Scopus and Web of Science) in June 2021 by three independent reviewers. The search equation used was: "Supplementation" AND ("Vitamin E" OR Tocopherol OR Tocotrienol) AND "breast cancer" AND (chemotherapy OR therapy OR prevention). In vitro studies and animal models of breast cancer supplemented with tocopherol or tocotrienol vitamers, alone or in combination, were included.

RESULTS

The results revealed 8546 relevant studies that were initially identified in our search. After analysis, a total of 12 studies were eligible for this systematic review. All studies included animal models, and 5 of them also performed in vitro experiments on cancer cell lines. The studies performed supplementation with tocopherols, mixtures (tocopherols and tocotrienols) and synthetic vitamin E forms. There was an significant association of estradiol, dendritic cells and pterostilbene in combined therapy with vitamin E. Vitamin E delayed tumor development, reduced tumor size, proliferation, viability, expression of anti-apoptotic and cell proliferation genes, and upregulated pro-apoptotic genes, tumor suppressor genes and increased immune response. The effects on oxidative stress markers and antioxidant activity were conflicting among studies. Only one study with synthetic vitamin E reported cardiotoxicity, but it did not show vitamin E genotoxicity.

CONCLUSION

In conclusion, vitamin E isoforms, isolated or associated, showed antitumor and chemopreventive activity. However, due to studies heterogeneity, there is a need for further analysis to establish dose, form, supplementation time and breast cancer stage.

Localized Interleukin-12 for Cancer Immunotherapy

Interleukin-12 (IL-12) is a potent, pro-inflammatory type 1 cytokine that has long been studied as a potential immunotherapy for cancer. Unfortunately, IL-12's remarkable antitumor efficacy in preclinical models has yet to be replicated in humans. Early clinical trials in the mid-1990's showed that systemic delivery of IL-12 incurred dose-limiting toxicities. Nevertheless, IL-12's pleiotropic activity, i.e., its ability to engage multiple effector mechanisms and reverse tumor-induced immunosuppression, continues to entice cancer researchers. The development of strategies which maximize IL-12 delivery to the tumor microenvironment while minimizing systemic exposure are of increasing interest. Diverse IL-12 delivery systems, from immunocytokine fusions to polymeric nanoparticles, have demonstrated robust antitumor immunity with reduced adverse events in preclinical studies. Several localized IL-12 delivery approaches have recently reached the clinical stage with several more at the precipice of translation. Taken together, localized delivery systems are supporting an IL-12 renaissance which may finally allow this potent cytokine to fulfill its considerable clinical potential. This review begins with a brief historical account of cytokine monotherapies and describes how IL-12 went from promising new cure to ostracized black sheep following multiple on-study deaths. The bulk of this comprehensive review focuses on developments in diverse localized delivery strategies for IL-12-based cancer immunotherapies. Advantages and limitations of different delivery technologies are highlighted. Finally, perspectives on how IL-12-based immunotherapies may be utilized for widespread clinical application in the very near future are offered.

Lipid nanoparticles that deliver IL-12 messenger RNA suppress tumorigenesis in MYC oncogene-driven hepatocellular carcinoma

Interleukin-12 (IL-12) is a promising candidate for cancer immunotherapy because of its ability to activate a number of host immune subsets that recognize and destroy cancer cells. We found that human hepatocellular carcinoma (HCC) patients with higher than median levels of IL-12 have significantly favorable clinical outcomes. Here, we report that a messenger RNA (mRNA) lipid nanoparticle delivering IL-12 (IL-12-LNP) slows down the progression of MYC oncogene-driven HCC. IL-12-LNP was well distributed within the HCC tumor and was not associated with significant animal toxicity. Treatment with IL-12-LNP significantly reduced liver tumor burden measured by dynamic magnetic resonance imaging (MRI), and increased survival of MYC-induced HCC transgenic mice in comparison to control mice. Importantly, IL-12-LNP exhibited no effect on transgenic MYC levels confirming that its therapeutic efficacy was not related to the downregulation of a driver oncogene. IL-12-LNP elicited marked infiltration of activated CD44⁺ CD3⁺ CD4⁺ T helper cells into the tumor, and increased the production of Interferon γ (IFNγ). Collectively, our findings suggest that IL-12-LNP administration may be an effective immunotherapy against HCC.

New insights into IL-12-mediated tumor suppression

During the past two decades, interleukin-12 (IL-12) has emerged as one of the most potent cytokines in mediating antitumor activity in a variety of preclinical models. Through pleiotropic effects on different immune cells that form the tumor microenvironment, IL-12 establishes a link between innate and adaptive immunity that involves different immune effector cells and cytokines depending on the type of tumor or the affected tissue. The robust antitumor response exerted by IL-12, however, has not yet been successfully translated into the clinics. The majority of clinical trials involving treatment with IL-12 failed to show sustained antitumor responses and were associated to toxic side effects. Here we discuss the therapeutic effects of IL-12 from preclinical to clinical studies, and will highlight promising strategies to take advantage of the antitumor activity of IL-12 while limiting adverse effects.

Pentoxifylline and its major oxidative metabolites exhibit different pharmacological properties

Previous investigations indicate that some of the metabolites of the hemorheological agent pentoxifylline (PTX), namely 1-(5-hydroxyhexyl)-3,7-dimethylxanthine (M1), 1-(4-carboxybutyl)-3,7-dimethylxanthine (M4) and 1-(3-carboxypropyl)-3,7-dimethylxanthine (M5), concur to some of the biological effects of the drug. However, information on the bioactivity of the major circulating oxidative metabolites of PTX (M4 and M5) is scanty. Here, we compared the effects of M4 and M5 with that of PTX and its major reductive metabolite, M1, on TNF-alpha production and cytotoxicity, endothelial cell proliferation and on the ATPase activity related to some ATP-binding cassette (ABC) transporters. Unlike PTX and M1, M4 and M5 poorly inhibited lipopolysaccaride-stimulated tumor necrosis factor-alpha (TNF-alpha) release by RAW 264.7 murine macrophages, and did not affect at all cell proliferation and upregulation of TNF-alpha-induced vascular cell adhesion molecule-1 (VCAM-1) in H5V endothelioma cells. By contrast, M4 and M5 were more effective than PTX and M1 in protecting WC/1 murine fibrosarcoma cells from TNF-alpha cytotoxicity. Moreover, results from ATP hydrolase assays indicated that neither PTX nor its tested metabolites interacted significantly with the human multidrug resistance transporters p-glycoprotein/multidrug resistance 1 (MDR1), multidrug resistance-related protein 1 (MRP1), and breast cancer resistance protein (BCRP). Based on these results and literature data, M5, retaining some of the PTX effects but lacking in significant inhibition of TNF-alpha production, may be a promising candidate drug for certain pathologic conditions.

Identification of H-2Db-Specific CD8+ T-Cell Epitopes From Mouse VEGFR2 That Can Inhibit Angiogenesis and Tumor Growth

Vascular endothelial growth factor receptor 2 (VEGFR2/KDR) plays a crucial role in tumor-associated angiogenesis and vascularization. It has been established that monoclonal antibodies against VEGFR2 can inhibit angiogenesis. In this study, two naturally processed CD8 T-cell epitopes (VILTNPISM and FSNSTNDILI) were identified from murine KDR. Cytotoxic T lymphocytes targeting endothelial cells could be directly monitored by KDR2 and KDR3 Elispots or major histocompatibility complex class I tetramer staining. Immunization with these two peptides effectively reduced angiogenesis and inhibited tumor growth in mouse models. Thus, vaccination with KDR peptides alone or in combination with other anti-angiogenesis agents may afford a novel immunotherapy for inhibition of tumor growth.

Interleukin-12 inhibits tumor growth in a novel angiogenesis canine hemangiosarcoma xenograft model

We established a canine hemangiosarcoma cell line derived from malignant endothelial cells comprising a spontaneous tumor in a dog to provide a renewable source of endothelial cells for studies of angiogenesis in malignancy. Pieces of the hemangiosarcoma biopsy were engrafted subcutaneously in a bg/nu/XID mouse allowing the tumor cells to expand in vivo. A cell line, SB-HSA, was derived from the xenograft. SB-HSA cells expressed vascular endothelial growth factor (VEGF) receptors 1 and 2, CD31, CD146, and alpha(v)beta(3) integrin, and produced several growth factors and cytokines, including VEGF, basic fibroblast growth factor, and interleukin (IL)-8 that are stimulatory to endothelial cell growth. These results indicated that the cells recapitulated features of mitotically activated endothelia. In vivo, SB-HSA cells stimulated robust angiogenic responses in mice and formed tumor masses composed of aberrant vascular channels in immunocompromised mice providing novel opportunities for investigating the effectiveness of antiangiogenic agents. Using this model, we determined that IL-12, a cytokine with both immunostimulatory and antiangiogenic effects, suppressed angiogenesis induced by, and tumor growth of, SB-HSA cells. The endothelial cell model we have described offers unique opportunities to pursue further investigations with IL-12, as well as other antiangiogenic approaches in cancer therapy.

Cytokine gene therapy for cancer with naked DNA

Plasmid DNA vectors (naked DNA) can easily be purified and transferred in vivo by intramuscular or intradermal injection. Naked DNA is stable in vivo, and long-term expression of the encoded protein is seen without chromosomal integration. Gene gun-mediated delivery of an expression plasmid is slightly more complicated but more efficient. These techniques have been applied to DNA vaccination or cytokine gene therapy for various diseases, including infections, autoimmune disorders, and cancer. We review cytokine gene therapy for cancer with naked DNA in animal models and present our preliminary data on gene gun-mediated in vivo transfection with the interleukin-12 gene in a murine renal cancer model. Because of its safety, simplicity, and low cost, cytokine gene therapy with naked DNA may become an important cancer treatment.

Suppression of metastatic hemangiosarcoma by a parvovirus MVMp vector transducing the IP-10 chemokine into immunocompetent mice

We have previously shown that the growth of human tumor xenografts in immunodeficient mice can be efficiently suppressed upon infection with the autonomous parvovirus H-1 or with cytokine-transducing derivatives thereof. To further evaluate the benefits of implementing parvoviruses in cancer gene therapy, we have created a new recombinant vector, MVMp/IP-10, transducing the immunoactive, antiangiogenic chemokine IP-10, and used this virus to treat syngeneic tumors grown in immunocompetent mice. Intratumoral/intraperitoneal administration of only 3 x 10(7) replication units of MVMp/IP-10 per animal strongly inhibited the progression of established H5V cell-induced vascular tumors, a highly malignant mouse model for human cavernous hemangioma and Kaposi's sarcoma. Retardation of recurrent tumor growth and suppression of life-threatening metastatic dissemination to internal organs were accompanied by a striking delay in hemangioma-associated mortality. Parental MVMp did not have a significant effect under these conditions up to the dose of 10(10) infectious units/animal, but had strong antihemangiosarcoma activity when used to infect H5V cells ex vivo prior to implantation. In all cases, virus therapy was very well tolerated. Virus-induced suppression of hemangiosarcoma was dependent on host T cells and associated with intratumoral persistence of IFN gamma-expressing cytotoxic lymphocytes, and led to the reduced expression of hepatic plasminogen activator inhibitor-1 (PAI-1), a metastasis-linked marker. This proof of principle study demonstrates that MVMp/IP-10 can aid the treatment of vascular tumors and that autonomous parvovirus-based vectors can be considered potent tools for cancer gene therapy purposes.

Flow cytometric cytotoxicity assay for measuring mammalian and avian NK cell activity

BACKGROUND

Flow-cytometric assays are convenient alternatives to classic radioactive natural killer (NK) tests. MitoTracker Green FM, a green fluorescent intracellular probe serving originally for staining mitochondria, seemed especially suitable for labeling NK target cells. Materials and Methods NK target cells were labeled with MitoTracker Green FM. After incubation with effector spleen cells, cell suspensions were stained with propidium iodide (PI), and flow-cytometric analysis was performed.

RESULTS

MitoTracker Green FM stained efficiently each cell type we assayed, including resting cells, and it was not released from dead cells. NK assays were set up using mouse spleen effector cells and K562 NK target cells. MitoTracker Green FM and PI double staining allowed a discrimination of live and dead target cells, and the cytotoxicity values were in the expected range. Then the method was applied to a less well-known chicken model. We found that chicken-skin fibroblasts had a definite sensitivity to autologous splenic NK cells, sometimes as high as the sensitivity of classic NK targets.

CONCLUSIONS

Convenient flow-cytometric NK tests can be performed by MitoTracker Green FM and PI staining. Using this method, we demonstrated that chicken fibroblasts are sensitive to the cytotoxic effect of autologous NK cells.

Use of Immunodeficient Mice for the Evaluation of CXC Chemokines in the Regulation of Tumor-associated Angiogenesis

Angiogenesis, defined as the growth of new capillaries from pre-existing vessels, is a pervasive biological phenomenon that is at the core of many physiologic and pathologic processes such as tumor growth. The use of human tumor xenografts in immunodeficient mice has provided significant insight into the biology of angiogenesis as it relates to tumor growth and metastasis. Work reviewed in this article supports the notion that net tumor-derived angiogenesis during tumorigenesis of human tumors is determined, in part, by an imbalance in favor of the overexpression of angiogenic (compared with angiostatic) juxtaposed cysteine residue (CXC) chemokines. This paradigm predicts an environment that favors angiogenesis (tumorigenesis) and supports the potential for spontaneous metastases. The article describes the use of immunodeficient mice as an animal model system for characterizing the qualitative and quantitative presence of these angiogenic and angiostatic CXC chemokines during tumorigenesis, as well as determining their net contribution to human tumorigenesis and metastasis in vivo. Various cancer cell lines have been used and xenografted into immunodeficient mice to create human tumor/mouse chimeras, indicating that an imbalance in the biology of angiogenic versus angiostatic CXC chemokines supports a significant portion of human tumor-derived angiogensis that leads to augmented tumorigenesis and spontaneous metastases. It has also been possible to identify potentially therapeutic novel strategies to manipulate the imbalance of angiogenic (compared with angiostatic) CXC chemokines, which may be directly translational to human disease.