Gene Therapy in Clinical Trials
The gene therapy industry is striving more than ever to define a path to the clinic and the market. Up to now, approximately 20 gene therapy products have been approved and almost 2600 human gene therapy clinical trials have already been reported around the world. These advancements raise great hope to treat devastating rare and metabolic disorders as well as incurable illnesses. Understanding the precise pathomechanisms of diseases, together with the development of efficient and special gene targeting tools and delivery systems are innovating the global market. At present, the field of gene therapy is starting to be commercially profitable as a variety of gene and cell-based gene therapy products have entered clinical practice. This article presents the current analysis of clinical trials that have been or are being employed in the market.
What Is Gene Therapy?
In medicine, gene therapy is used as a therapeutic strategy that transfers DNA or RNA fragments to patients' cells to correct a defective gene or a gene product in order to treat disorders, even cancers, that aren't curable with conventional drugs. There're two principal methods in advanced clinical gene therapies, including direct in vivo administration of manipulated viral vectors for gene delivery and ex vivo genetically engineered stem cells (non-viral vectors). A number of approaches to gene therapy are being tested, for example:
- Substituting a mutated gene (resulting in disease) with a healthy copy of the gene;
- Knocking out a mutated gene or inactivating a dysfunctional gene;
- Introducing an intact new gene into the body to assist in fighting disease.
Progress and Current Trends in Gene Therapy
The first gene therapy clinical trials were launched over two decades ago. The most dramatic event in this field has been the initiation of clinical trials referring to the introduction of genetically altered cells or genes into human beings. Performing the following methods, a suite of Phase I/II trials have been launched in the past with excellent clinical results and no side effects reported. Highly efficient gene targeting strategies and site-directed gene-editing tools have also been developed and applied clinically.
Figure 1. In vivo and ex vivo gene therapy concepts. (Kaufmann, 2013)
- Gene editing methods
Gene editing begins with making a break at a specific position of DNA sequences, including directed repair and non-directed repair. These two kinds of repair ways act with different effects. Breaks in DNA proceed all the time and the cell in the body is capable of repairing them. The technique targets a type of molecular scissors termed nucleases to create a break in a specific gene. In particular, siRNA-based therapeutics that has made great progress in clinical trials are currently coming into our view.
- Gene addition methods
Gene addition technique makes use of a delivery system (vectors) to insert new genes directly into cells. The vectors may be selected parts of viruses that have been genetically modified to deliver the healthy copy of genes into cells without evoking an individual to be subjected to the original disease. The viruses are chosen because of their natural ability to transport genetic materials into cells. Gene addition of a functional gene can happen either inside or outside the body.
- Gene-based immunotherapies
Adding a gene to an organism's immune system cells can facilitate them to work more effectively against various diseases. Gene-based immunotherapies can operate several kinds of vectors to deliver new DNA into cells, including retroviral vectors, and other vectors originated from adenovirus, adeno-associated virus, and herpesvirus. Nowadays, these approaches are being developed to help immune relevant cells (e.g. T cells) to locate and destroy cancer cells. For instance, chimeric antigen receptor T (CAR-T) cells and CRISPR/Cas9 technology.
Revitalized Interest in Gene Therapy
Recently, the level of interest in gene therapy from industry and pharmaceutical companies has been unprecedented. In the Tab.1, there is a list of several so-far approved human gene and cell-based gene therapy products. One of the standout therapies in cancer immunotherapy is using CAR-T cells to target tumor-associated antigens (TAAs) on the cell surface. The approach has received extensive attention and combines the expansion capacity and persistence of cytotoxic T cells with the specificity of monoclonal antibodies to treat tumors, where other cancer therapies often have been failed. In May 2017, the first pediatric patient treated with CAR-T cell therapy marked 5 years in remission, and the first CAR-T cell product (Kymriah) has been approved by the Food and Drug Administration (FDA) in this year. Notably, the first CRISPR-based gene therapy trial incorporates CAR-T and PD-1 immunotherapy methods. Clinical trials testing CRISPR immunotherapy to combat cancers may have started as early as 2015 in China.
Tab.1 Approved gene therapy products. (Ginn, 2018)
Today, there has been an increasing trend of sponsored research in the academic sector, which largely expands the gene therapy developmental pipeline in the future. As a leading provider in the gene therapy market, Creative Biolabs is dedicated to promoting pharmaceutical development with our abundant experience and extensive expertise. If you'd like to know more about gene therapy or related siRNA custom services, please directly contact us or send an e-mail with your specific request.
References
- Kaufmann, K.B.; et al. (2013). Gene therapy on the move. EMBO Mol Med. 5(11): 1642-1661.
- Ginn, S.L.; et al. (2018). Gene therapy clinical trials worldwide to 2017: An update. J Gene Med. 20(5): e3015.
