Gene therapy for patients

Cancer is a disease that occurs due to different mutations and changes in the DNA that make cells grow and reproduce without control. Cancerous cells can invade and destroy surrounding healthy tissue, including organs. This condition is nowadays the second leading cause of death worldwide just behind cardiovascular diseases despite the great advances scientists have achieved in understanding the different processes involved in the development and progression of this cancer. There is a lack of treatments for those types of cancers with poor prognosis and low five-year survival rates such as pancreatic cancer, with a 5-year survival rate of 4%, lung cancer, with a 5-year survival rate of 15%, liver cancer or glioblastoma, with 5-year survival rates of 7% and 5% respectively.

Usually, the main treatment options for cancer are surgery, sometimes followed by chemotherapy or radiation therapy. However,  some types of cancers are resistant to these treatments. Moreover, these therapies can have serious negative side effects that decrease the patient’s adherence to the treatment. Therefore, scientists all over the world are working hard to find new treatments to alleviate the death toll caused by this condition. An emerging field in this area is gene therapy, which can offer potential treatments. 

Gene therapy can be defined as the introduction of a normal gene into the genome to replace an abnormal gene responsible for causing a certain disease. It is considered to have the potential to revolutionize cancer treatment.

Types of gene therapy

Some of the gene therapy treatments that have been developed are:

• Immunotherapy, which consists in manipulating your own immune system to destroy cancerous cells. In this case, gene therapy is used to create cancer vaccines to train the immune system to recognize and attack cancer cells.  However, it has a big limitation since sometimes cancer cells could develop mechanisms to identify these mechanisms and to avoid them. There are several types of immunotherapy, including:
  • Immune checkpoint inhibitors: are drugs used to block immune checkpoints, allowing immune cells to respond better to cancer.
  • T-cell transfer therapy: consists in a treatment that boosts the ability of T cells to fight against cancer.
  • Monoclonal antibodies: scientists have created proteins designed to bind to specific targets on cancer cells.
  • Treatment vaccines: these vaccines enhance your immune system and attack cancer cells. 
  • Immune system modulators: are substances created to boost your immune response against cancer.

• Gene transfer, which consists in the introduction of a foreign gene into cancer cells.  Oncolytic vectors are usually viruses, such as adenovirus, herpes simplex virus, etc., that are used to deliver these genes. They have been used in different studies and clinical trials to target and destroy only cancer cells leaving the rest of the body’s cells untouched. 
• CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) technique is a therapy created in 2015 when researchers learned to use the CRISPR tool outside of bacteria to cut and paste bits of genetic material into any cell. The technique was inspired by how bacteria protect themselves against intruders like viruses by capturing the intruder’s DNA and storing them as segments called CRISPRs. If the virus or another microbe attacks again, these DNA segments help bacteria to recognize them and cut the invader’s DNA. The technique imitates this process and consists in building a guide RNA capable of recognizing the part of DNA that scientists want to edit. The RNA binds to a protein called CAS and directs the work of these “molecular scissors”. RNA-guided CAS scissors search for the specific sequence and cut it. 

What are the side effects of gene therapy?

Gene therapies have different long-term side effects. For example, a patient’s immune system can react to the vectors and produce the main symptoms such as infections like fever, chills, nausea, etc. However, scientists have not yet identified any side effects on the clinical trials

The future of cancer treatment

Cancer represents a burden since it is the second leading cause of death worldwide and a serious health and economic issue for governments. The field of cancer treatment, particularly gene therapy, is evolving quickly. Several vaccines are being tested in different clinical trials and extensive progress has been made in oncolytic virotherapy. Scientists hope that the new advances in cancer therapy will help to decrease the death toll of this condition and turn cancer, in the future, into a manageable chronic disease.