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What is gene and cell therapy?

Gene and cell therapy is at the forefront of medical science and has the potential to transform the treatment of some of the most challenging diseases. Gene and cell therapy is the treatment of disease by delivering therapeutic DNA into a patient’s cells either in the body (in vivo) or outside the body (ex vivo). The new DNA can be used to replace or correct a faulty gene, or to encode a therapeutic protein as a treatment. The approach offers the prospect of single dose, long-term and possibly permanent treatment or cure for many common and rare diseases which currently have poor treatment options.

Vectors are targeted and specific
Therapeutic DNA is introduced into the target tissue using viral based vectors: these are viruses which have been modified so they are safe and can carry the required DNA/genetic payload into the target cell, either in vivo or ex vivo.

The most commonly used vectors in gene therapy are those based on either adeno-associated viruses (AAV) or lentiviruses. Lentiviral based vectors such as our LentiVector® platform have several advantages over AAV based vectors - they can carry a larger therapeutic genetic payload, and they can stably modify both dividing and non-dividing cells, making them suitable for use in cell therapy. Also, unlike AAV, there is no pre-existing immune response.

Gene therapy strategies
There are several gene therapy approaches in development. One of the most common involves administering healthy genes to patients who have inherited a faulty copy of a gene. For example, SAR422459 inserts the healthy ABCR gene into the retina of patients with Stargardt disease and, similarly, SAR421869 delivers a healthy MYO7A gene to treat patients with Usher syndrome type 1B. Conversely, gene therapy can be used to inactivate, or “knock out”, a gene that is functioning improperly (gene silencing).

Gene therapy also provides us with the ability to introduce one or more genes into cells to help modulate the body’s response to disease. For example to treat Parkinson’s disease a lentiviral vector (e.g. OXB-102) delivering three genes can be used to stably modify neuronal cells to turn them into endogenous factories making dopamine; this is the neurotransmitter that is required to treat this disease. The benefit of gene therapy is that a number of genes can be delivered to work together in combination over a sustained period of time unlike most drugs which require frequent administration, typically daily.

Cell therapy applications for gene therapy
Cell therapy usually involves the modification of cells in some way. These cells are then used as therapeutic agents to treat or prevent disease through their introduction back into the body. One of the main ways to modify the cells is through gene therapy and a successful cell therapy approach at present is the use of CAR-T as explained below.

CAR-T technology explained
Chimeric antigen receptors (CARs), also known as artificial T-cell receptors are genetically engineered receptors which graft a new specificity onto an immune effector cell. Typically, these receptors are used to graft the specificity of a monoclonal antibody onto a T-cell; normally carried out by a lentiviral vector. CAR T-cells are under investigation as a therapy for cancer, using a technique called adoptive cell transfer in which T-cells are removed from a patient and modified so that they express receptors specific to the particular form of cancer. The T-cells are reintroduced into the patient with the ability to recognise and kill the targeted cancer cells. In addition, these CAR T-cells proliferate, thus amplifying the beneficial response. This is a very powerful therapy and has led to dramatic response rates.

LentiVectortechnology for orphan indications, and the Company has a number of other licensing agreements covering its 5T4 and PrimeBoost technologies.

Facts

Research

We are world leaders in the development of lentiviral vectors and our scientists are named authors on multiple publications


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The new medicines and treatments we are developing could improve life for millions of people