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Awad RM, Breckpot K. Novel technologies for applying immune checkpoint blockers. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2023; 382:1-101. [PMID: 38225100 DOI: 10.1016/bs.ircmb.2023.03.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
Abstract
Cancer cells develop several ways to subdue the immune system among others via upregulation of inhibitory immune checkpoint (ICP) proteins. These ICPs paralyze immune effector cells and thereby enable unfettered tumor growth. Monoclonal antibodies (mAbs) that block ICPs can prevent immune exhaustion. Due to their outstanding effects, mAbs revolutionized the field of cancer immunotherapy. However, current ICP therapy regimens suffer from issues related to systemic administration of mAbs, including the onset of immune related adverse events, poor pharmacokinetics, limited tumor accessibility and immunogenicity. These drawbacks and new insights on spatiality prompted the exploration of novel administration routes for mAbs for instance peritumoral delivery. Moreover, novel ICP drug classes that are adept to novel delivery technologies were developed to circumvent the drawbacks of mAbs. We therefore review the state-of-the-art and novel delivery strategies of ICP drugs.
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Affiliation(s)
- Robin Maximilian Awad
- Laboratory for Molecular and Cellular Therapy, Department of Biomedical Sciences, Vrije Universiteit Brussel, Brussels, Belgium
| | - Karine Breckpot
- Laboratory for Molecular and Cellular Therapy, Department of Biomedical Sciences, Vrije Universiteit Brussel, Brussels, Belgium.
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2
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Basudan AM. The Role of Immune Checkpoint Inhibitors in Cancer Therapy. Clin Pract 2022; 13:22-40. [PMID: 36648843 PMCID: PMC9844484 DOI: 10.3390/clinpract13010003] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/18/2022] [Accepted: 12/22/2022] [Indexed: 12/29/2022] Open
Abstract
Over the years, immune checkpoint inhibitors (CPIs) have become a powerful treatment strategy in the field of cancer immunotherapy. In the last decade, the number of FDA-approved CPIs has been increasing prominently, opening new horizons for the treatment of a wide range of tumor types. Pointedly, three immune checkpoint molecules have been under extensive research, which include cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein-1 (PD-1) and its ligand-1 (PD-L1). Despite remarkable success, not all patients respond positively to therapy, which highlights the complexity of the tumor microenvironment (TME) and immune system. This has led to the identification of molecular biomarkers to predict response and toxicity. In addition, there has been an emerging focus on developing new delivery and targeting approaches for better drug efficacy and potency. In this review, we highlight the mechanism of action of major CPIs, their clinical impact, variation in effectiveness, response prediction, updated clinical indications, current challenges and limitations, promising novel approaches, and future directions.
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Affiliation(s)
- Ahmed M Basudan
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Saud University, Riyadh 12372, Saudi Arabia
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3
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Barati M, Mirzavi F, Atabaki M, Bibak B, Mohammadi M, Jaafari MR. A review of PD-1/PD-L1 siRNA delivery systems in immune T cells and cancer cells. Int Immunopharmacol 2022; 111:109022. [PMID: 35987146 DOI: 10.1016/j.intimp.2022.109022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 06/20/2022] [Accepted: 06/30/2022] [Indexed: 11/19/2022]
Abstract
OBJECTIVES Programmed cell death 1 (PD-1) is a member of the CD28/CTLA-4 family of inhibitory immunological checkpoint receptors that's also widely produced by exhausted T lymphocytes in an immunosuppressive tumor microenvironment. PD-1 binds to programmed death ligand (PD-L1) and suppresses anti-cancer activity of T lymphocytes. We examined the current literature on how siRNA delivery systems can be used to target PD-1 and PD-L1, as well as the anti-cancer mechanisms and challenges associated with siRNA molecules. We look at studies that use program death 1 siRNA or program death 1 ligand siRNA to treat cancer. Several databases have been used for this purpose, including NCBI, Scopus, and Google Scholar. KEY FINDINGS This study looked at several methods for delivering siRNA to immune cells and cancer cells. According to these findings, suppressing PD-1 in T cells increases T lymphocyte activity. PD-L1 suppression in DCs improves antigen presentation and co-stimulatory signals on their surface, resulting in T cell activation. Chemotherapy resistance and cancer cell suppression of T cells are reduced when PD-L1/2 is suppressed in cancer cells. CONCLUSION The findings of this study indicated that several strategies for siRNA transfection to immune and cancer cells have been evaluated in recent decades, some of which effectively transfect siRNA to target cells, and defined PD-1 siRNA as a promising strategy for cancer treatment.
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Affiliation(s)
- Mehdi Barati
- Department of Pathobiology and Laboratory Sciences, North Khorasan University of Medical Sciences, Bojnurd, Iran
| | - Farshad Mirzavi
- Cardiovascular Diseases Research Center, Birjand University of Medical Sciences, Birjand, Iran
| | - Mahdi Atabaki
- Clinical Immunology Research Center, Zahedan University of Medical Sciences, Zahedan, Iran
| | - Bahram Bibak
- Department of Physiology, School of Medicine, North Khorasan University of Medical Sciences, Bojnurd, Iran
| | - Mojgan Mohammadi
- Immunology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mahmoud Reza Jaafari
- Biotechnology Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran; Department of Pharmaceutical Nanotechnology, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran.
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4
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Collins SA, Shah AH, Ostertag D, Kasahara N, Jolly DJ. Clinical development of retroviral replicating vector Toca 511 for gene therapy of cancer. Expert Opin Biol Ther 2021; 21:1199-1214. [PMID: 33724117 PMCID: PMC8429069 DOI: 10.1080/14712598.2021.1902982] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 03/10/2021] [Indexed: 01/23/2023]
Abstract
INTRODUCTION The use of tumor-selectively replicating viruses is a rapidly expanding field that is showing considerable promise for cancer treatment. Retroviral replicating vectors (RRV) are unique among the various replication-competent viruses currently being investigated for potential clinical utility, because they permanently integrate into the cancer cell genome and are capable of long-term persistence within tumors. RRV can mediate efficient tumor-specific delivery of prodrug activator genes, and subsequent prodrug treatment leads to synchronized cell killing of infected cancer cells, as well as activation of antitumor immune responses. AREAS COVERED Here we review preclinical studies supporting bench-to-bedside translation of Toca 511, an optimized RRV for prodrug activator gene therapy, the results from Phase I through III clinical trials to date, and potential future directions for this therapy as well as other clinical candidate RRV. EXPERT OPINION Toca 511 has shown highly promising results in early-stage clinical trials. This vector progressed to a registrational Phase III trial, but the results announced in late 2019 appeared negative overall. However, the median prodrug dosing schedule was not optimal, and promising possible efficacy was observed in some prespecified subgroups. Further clinical investigation, as well as development of RRV with other transgene payloads, is merited.
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Affiliation(s)
- Sara A Collins
- Department of Neurological Surgery, University of California, San Francisco (UCSF), San Francisco, California, United States of America
| | - Ashish H Shah
- Department of Neurological Surgery, Miller School of Medicine, University of Miami, Florida, United States of America
| | - Derek Ostertag
- Tocagen, Inc., San Diego, California, United States of America
| | - Noriyuki Kasahara
- Department of Neurological Surgery, University of California, San Francisco (UCSF), San Francisco, California, United States of America
- Department of Radiation Oncology, University of California, San Francisco (UCSF), California, United States of America
| | - Douglas J Jolly
- Tocagen, Inc., San Diego, California, United States of America
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5
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Donkor M, Jones HP. The Proposition of the Pulmonary Route as an Attractive Drug Delivery Approach of Nano-Based Immune Therapies and Cancer Vaccines to Treat Lung Tumors. FRONTIERS IN NANOTECHNOLOGY 2021. [DOI: 10.3389/fnano.2021.635194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Lung cancer is the leading cause of cancer related deaths globally, making it a major health concern. The lung’s permissive rich microenvironment is ideal for supporting outgrowth of disseminated tumors from pre-existing extra-pulmonary malignancies usually resulting in high mortality. Tumors occurring in the lungs are difficult to treat, necessitating the need for the development of advanced treatment modalities against primary tumors and secondary lung metastasis. In this review, we explore the pulmonary route as an attractive drug delivery approach to treat lung tumors. We also discuss the potential of pulmonary delivery of cancer vaccine vectors to induce mucosal immunity capable of preventing the seeding of tumors in the lung.
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Lamichhane P, Deshmukh R, Brown JA, Jakubski S, Parajuli P, Nolan T, Raja D, Badawy M, Yoon T, Zmiyiwsky M, Lamichhane N. Novel Delivery Systems for Checkpoint Inhibitors. MEDICINES (BASEL, SWITZERLAND) 2019; 6:E74. [PMID: 31373327 PMCID: PMC6789831 DOI: 10.3390/medicines6030074] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 07/08/2019] [Accepted: 07/10/2019] [Indexed: 12/16/2022]
Abstract
Checkpoint inhibition (CPI) therapies have been proven to be powerful clinical tools in treating cancers. FDA approvals and ongoing clinical development of checkpoint inhibitors for treatment of various cancers highlight the immense potential of checkpoint inhibitors as anti-cancer therapeutics. The occurrence of immune-related adverse events, however, is a major hindrance to the efficacy and use of checkpoint inhibitors as systemic therapies in a wide range of patients. Hence, methods of sustained and tumor-targeted delivery of checkpoint inhibitors are likely to improve efficacy while also decreasing toxic side effects. In this review, we summarize the findings of the studies that evaluated methods of tumor-targeted delivery of checkpoint inhibitors, review their strengths and weaknesses, and discuss the outlook for therapeutic use of these delivery methods.
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Affiliation(s)
- Purushottam Lamichhane
- School of Dental Medicine, Lake Erie College of Osteopathic Medicine, 4800 Lakewood Ranch Blvd, Bradenton, FL 34211, USA
| | - Rahul Deshmukh
- School of Pharmacy, Lake Erie College of Osteopathic Medicine, 5000 Lakewood Ranch Blvd, Bradenton, FL 34211, USA
| | - Julie A Brown
- School of Dental Medicine, Lake Erie College of Osteopathic Medicine, 4800 Lakewood Ranch Blvd, Bradenton, FL 34211, USA
| | - Silvia Jakubski
- Department of Biostatistics, University of Florida, Gainesville, FL 32611, USA
| | - Priyanka Parajuli
- Department of Internal Medicine, Southern Illinois University, Springfield, IL 62702, USA
| | - Todd Nolan
- School of Dental Medicine, Lake Erie College of Osteopathic Medicine, 4800 Lakewood Ranch Blvd, Bradenton, FL 34211, USA
| | - Dewan Raja
- School of Dental Medicine, Lake Erie College of Osteopathic Medicine, 4800 Lakewood Ranch Blvd, Bradenton, FL 34211, USA
| | - Mary Badawy
- School of Dental Medicine, Lake Erie College of Osteopathic Medicine, 4800 Lakewood Ranch Blvd, Bradenton, FL 34211, USA
| | - Thomas Yoon
- School of Dental Medicine, Lake Erie College of Osteopathic Medicine, 4800 Lakewood Ranch Blvd, Bradenton, FL 34211, USA
| | - Mark Zmiyiwsky
- School of Dental Medicine, Lake Erie College of Osteopathic Medicine, 4800 Lakewood Ranch Blvd, Bradenton, FL 34211, USA
| | - Narottam Lamichhane
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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Mitchell LA, Yagiz K, Hofacre A, Viaud S, Munday AW, Espinoza FL, Mendoza D, Rodriguez-Aguirre ME, Bergqvist S, Haghighi A, Miner MV, Accomando WP, Burrascano C, Gammon D, Gruber HE, Jolly DJ, Lin AH. PD-L1 checkpoint blockade delivered by retroviral replicating vector confers anti-tumor efficacy in murine tumor models. Oncotarget 2019; 10:2252-2269. [PMID: 31040917 PMCID: PMC6481342 DOI: 10.18632/oncotarget.26785] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 03/04/2019] [Indexed: 12/31/2022] Open
Abstract
Immune checkpoint inhibitors (CPIs) are associated with a number of immune-related adverse events and low response rates. We provide preclinical evidence for use of a retroviral replicating vector (RRV) selective to cancer cells, to deliver CPI agents that may circumvent such issues and increase efficacy. An RRV, RRV-scFv-PDL1, encoding a secreted single chain variable fragment targeting PD-L1 can effectively compete with PD-1 for PD-L1 occupancy. Cell binding assays showed trans-binding activity on 100% of cells in culture when infection was limited to 5% RRV-scFv-PDL1 infected tumor cells. Further, the ability of scFv PD-L1 to rescue PD-1/PD-L1 mediated immune suppression was demonstrated in a co-culture system consisting of human-derived immune cells and further demonstrated in several syngeneic mouse models including an intracranial tumor model. These tumor models showed that tumors infected with RRV-scFv-PD-L1 conferred robust and durable immune-mediated anti-tumor activity comparable or superior to systemically administered anti-PD-1 or anti PD-L1 monoclonal antibodies. Importantly, the nominal level of scFv-PD-L1 detected in serum is ∼50–150 fold less than reported for systemically administered therapeutic antibodies targeting immune checkpoints. These results support the concept that RRV-scFv-PDL1 CPI strategy may provide an improved safety and efficacy profile compared to systemic monoclonal antibodies of currently approved therapies.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Amy H Lin
- Tocagen Inc., San Diego, 92121, CA, USA
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Li Y, Han H, Yin J, He X, Tang Z, Li T, Yao K, Yin Y. d- andl-Aspartate regulates growth performance, inflammation and intestinal microbial community in young pigs. Food Funct 2019; 10:1028-1037. [DOI: 10.1039/c8fo01410h] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Dietary 1%d-Asp andl-Asp affect the growth performance and inflammation in young pigs, which might be associated with gut microbiota.
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Affiliation(s)
- Yuying Li
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process; Key Laboratory of Agro-ecological Processes in Subtropical Region
- Institute of Subtropical Agriculture
- Chinese Academy of Sciences; National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production; Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central
- Ministry of Agriculture
- Changsha
| | - Hui Han
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process; Key Laboratory of Agro-ecological Processes in Subtropical Region
- Institute of Subtropical Agriculture
- Chinese Academy of Sciences; National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production; Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central
- Ministry of Agriculture
- Changsha
| | - Jie Yin
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process; Key Laboratory of Agro-ecological Processes in Subtropical Region
- Institute of Subtropical Agriculture
- Chinese Academy of Sciences; National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production; Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central
- Ministry of Agriculture
- Changsha
| | - Xingguo He
- Changsha LvYe Bio-technology Co
- Ltd
- Changsha
- China
| | - Zhiyi Tang
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process; Key Laboratory of Agro-ecological Processes in Subtropical Region
- Institute of Subtropical Agriculture
- Chinese Academy of Sciences; National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production; Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central
- Ministry of Agriculture
- Changsha
| | - Tiejun Li
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process; Key Laboratory of Agro-ecological Processes in Subtropical Region
- Institute of Subtropical Agriculture
- Chinese Academy of Sciences; National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production; Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central
- Ministry of Agriculture
- Changsha
| | - Kang Yao
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process; Key Laboratory of Agro-ecological Processes in Subtropical Region
- Institute of Subtropical Agriculture
- Chinese Academy of Sciences; National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production; Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central
- Ministry of Agriculture
- Changsha
| | - Yulong Yin
- Hunan Provincial Key Laboratory of Animal Nutritional Physiology and Metabolic Process; Key Laboratory of Agro-ecological Processes in Subtropical Region
- Institute of Subtropical Agriculture
- Chinese Academy of Sciences; National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production; Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production; Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central
- Ministry of Agriculture
- Changsha
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9
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Li Y, Han H, Yin J, Zheng J, Zhu X, Li T, Yin Y. Effects of glutamate and aspartate on growth performance, serum amino acids, and amino acid transporters in piglets. FOOD AGR IMMUNOL 2018. [DOI: 10.1080/09540105.2018.1437892] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Affiliation(s)
- Yuying Li
- Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, People’s Republic of China
- National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Changsha, Hunan, People’s Republic of China
- Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, Hunan, People’s Republic of China
- Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, Hunan, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing, People’s Republic of China
| | - Hui Han
- Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, People’s Republic of China
- National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Changsha, Hunan, People’s Republic of China
- Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, Hunan, People’s Republic of China
- Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, Hunan, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing, People’s Republic of China
| | - Jie Yin
- Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, People’s Republic of China
- National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Changsha, Hunan, People’s Republic of China
- Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, Hunan, People’s Republic of China
- Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, Hunan, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing, People’s Republic of China
| | - Jie Zheng
- Department of Animal Science, Hunan Agriculture University, Changsha, Hunan, People’s Republic of China
| | - Xiaotong Zhu
- College of Life Science, Guangxi Normal University, Guilin, Guangxi, People’s Republic of China
| | - Tiejun Li
- Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, People’s Republic of China
- National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Changsha, Hunan, People’s Republic of China
- Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, Hunan, People’s Republic of China
- Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, Hunan, People’s Republic of China
- Hunan Co-Innovation Center of Animal Production Safety, Changsha, Hunan, People’s Republic of China
| | - Yulong Yin
- Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, People’s Republic of China
- National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Changsha, Hunan, People’s Republic of China
- Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Changsha, Hunan, People’s Republic of China
- Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, Hunan, People’s Republic of China
- Hunan Co-Innovation Center of Animal Production Safety, Changsha, Hunan, People’s Republic of China
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Hofacre A, Yagiz K, Mendoza D, Lopez Espinoza F, Munday AW, Burrascano C, Singer O, Gruber HE, Jolly DJ, Lin AH. Efficient Therapeutic Protein Expression Using Retroviral Replicating Vector with 2A Peptide in Cancer Models. Hum Gene Ther 2018; 29:437-451. [PMID: 29216761 DOI: 10.1089/hum.2017.205] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Toca 511, a retroviral replicating vector (RRV), uses an internal ribosomal entry site (IRES) to express an optimized yeast cytosine deaminase (yCD2), which converts 5-fluorocytosine to 5-fluorouracil. This configuration is genetically stable in both preclinical mouse models and human clinical trials. However, the use of IRES (∼600 bp) restricts choices of therapeutic transgenes due to limits in RRV genome size. This study replaced IRES with 2A peptides derived from picornaviruses with or without a GSG linker. The data show that GSG-linked 2A (g2A) peptide resulted in higher polyprotein separation efficiency than non-GSG linked 2A peptide. The study also shows that RRV can tolerate insertion of two separate 2A peptides to allow expression of two transgenes without compromising the assembly and function of the virus in addition to insertion of a single 2A peptide to confirm genetic stability with yCD2, green fluorescent protein, and HSV-1 thymidine kinase. In a parallel comparison of the RRV-IRES-yCD2 and RRV-g2A-yCD2 configurations, the study shows the yCD2 protein expressed from RRV-g2A-yCD2 has higher activity, resulting in a higher survival benefit in an intracranial tumor mouse model. These data enable a wider range of potential product candidates that could be developed using the RRV platform.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Amy H Lin
- Tocagen, Inc. , San Diego, California
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