Gene Therapy Slides PDF

Pharmaceutical Biotechnology Gene Therapy Dr. Esra’a Alomari 2022/2023 Course Number: 05027125 Dr.Esra'a Alomari Introduction: The genes in body cells play a key role in health. Indeed, defective genes or genes can cause diseases....

Pharmaceutical Biotechnology Gene Therapy Dr. Esra’a Alomari 2022/2023 Course Number: 05027125 Dr.Esra'a Alomari Introduction: The genes in body cells play a key role in health. Indeed, defective genes or genes can cause diseases. Genetically inherited mutation: ü The whole or part of a gene is defective or missing from birth. Acquired mutations (can be caused by environmental exposures): ü Healthy genes can change (mutate) throughout life. ü Some inherited and acquired mutations can cause developmental disorders, neurological diseases, and cancer. Dr.Esra'a Alomari ZOLGENSMA Dr.Esra'a Alomari Human gene therapy: Human gene therapy seeks to modify or manipulate the expression of a gene or to alter the biological properties of living cells for therapeutic use. FDA: Gene therapy is a technique that modifies a person’s genes to treat or cure disease. Gene therapy products are being studied to treat diseases, including cancer, genetic diseases, and infectious diseases. Gene therapy is the use of nucleic acids as a pharmaceutical agent to treat disease FDA has approved multiple gene therapy products for cancer and rare disease indications. Dr.Esra'a Alomari v licensed products from the Office of Tissues and Advanced Therapies (OTAT). https://www.fda.gov/vaccines-blood-biologics/cellular-gene-therapy-products/approved- cellular-and-gene-therapy-products. The major disadvantage of gene therapy is that gene medicines are not easy to be formulated into conventional dosage forms and delivered for a routine use. The cost of gene therapy is so far also much higher compared with traditional medicines. Dr.Esra'a Alomari Dr.Esra'a Alomari Diseases studied in gene therapy trials Dr.Esra'a Alomari How Gene Therapy Works Gene therapies can work by several mechanisms: ü Replacing a disease-causing gene with a healthy copy of the gene. ü Inactivating a disease-causing gene that is not functioning correctly. ü Introducing a new or modified gene into the body to help treat disease Dr.Esra'a Alomari How Gene Therapy Works Dr.Esra'a Alomari Dr.Esra'a Alomari  Vectors: The vector, or vehicle, which is injected into the patient and by which a transgene is delivered to the targeted cells.. The vehicles used to introduce the transgene is known as vectors. They designed to deliver therapeutic genetic material, such as a working gene, directly into a cell. Dr.Esra'a Alomari  The utility of the vector depends: The size of the exogenous gene (transgene) The efficiency of the delivery. It will induce the host’s immune response or not. The stability and longevity of the transgene. Level of expression of a transgene. GT rely on the successful construction of a gene expression plasmid. Dr.Esra'a Alomari  Viral vectors: All viruses hold the inherited advantage to bind to their hosts and introduce their genetic material into the host cell with high efficiency. To construct a viral vector, the genes responsible for the viral replication and pathogenicity are first removed and replaced with a transgene cassette. Viral Vectors are manufactured in packaging cell lines such as HEK293 or A547 An ideal Viral Vector is genetically stable, safe to handle, non-toxic for host cells, has a high packaging capacity and transduction efficiency, and does not elicit an immune response. To date, approximately 70 % of all gene therapy clinical trials employ viral. Retrovirus, lentivirus, adenovirus, and adeno-associated virus (AAV) are the most extensively studied and used viral vectors for human gene therapy. Each of them has its unique characteristics, which affect their use as vehicles in gene therapy. Dr.Esra'a Alomari Dr.Esra'a Alomari Dr.Esra'a Alomari Integrating Viral vectors Lentivirus and Retrovirus vectors. These vectors: fuse a fragment of their genetic material into the host cell genome. are often characterized by stable and long-term expression of the transgene. Genetic integration does not guarantee stable expression as transgene expression can be gradually silenced over time. Integrating Viral Vectors are preferred in applications where stable genetic modification needs to be maintained in dividing cells. Dr.Esra'a Alomari Non-integrating Viral Vectors The DNA remains separate from the genome. AAV and Adenovirus vectors. The genetic material remains episomal in the cell cytoplasm. The main advantage is the low risk of genotoxicity caused by insertional mutagenesis. can provide stable transgene expression in non-dividing postmitotic cells, such as neurons, and transient or stable expression in dividing cells. Exhibit high transfer efficiency in both dividing and non-dividing cells and do not present a risk of insertional mutagenesis. Dr.Esra'a Alomari Dr.Esra'a Alomari Ex vivo: The cells are removed from the body, incubated with a vector, and the gene-engineered cells are returned to the body. This procedure is usually done with blood cells because they are the easiest to remove and return. Dr.Esra'a Alomari In vivo Viral Vectors carrying a transgene are directly administrated to the patient either by intravenous infusion (i.e. systemic administration) or by intraocular, intramuscular, intrathecal, or intraparenchymal injection into the organ of interest (i.e. local administration). This strategy has achieved success in the treatment of eye diseases, neurological disorders, and hemophilia. Dr.Esra'a Alomari Dr.Esra'a Alomari Dr.Esra'a Alomari Non-viral vector: Synthetic delivery vectors have the potential to address many of the limitations of viral vectors, particularly with respect to safety. Nonviral vectors are gene delivery vehicles that are inorganic particles, lipid-based vectors, polymer-based vectors, and peptide-based vectors. Nonviral gene therapy includes local administration of naked plasmids or using specialized carriers to deliver plasmids to this area. Normally, nonviral vectors are useful in delivering different types of nucleic acids, including small DNA (oligodeoxynucleotides), large DNA (plasmid DNA), and RNA (ribozymes, Si RNA, or mRNA). Dr.Esra'a Alomari Dr.Esra'a Alomari Non-viral vector: Ø The inherent problems with recombinant viruses such as immunogenicity ( reflected in the generation of neutralizing antibodies, and insertional mutagenesis) have called for the design of efficient, nonviral vectors for human gene therapy. Ø Nonviral vectors are significantly less immunogenic and are not likely to induce insertional mutagenesis and unwanted homologous recombination after uptake by the cells. Ø They are also relatively easy to be manipulated, produced, and purified in a large scale compared with their viral counterparts. Dr.Esra'a Alomari Dr.Esra'a Alomari  The clinical utility of non-viral vectors is still hampered by the low transfection efficiency: 1. Nonspecific uptake of the vector by epithelial barriers and extra-cellular matrix. 2. Poor delivery into the therapeutic target. Dr.Esra'a Alomari