14 Aug 2017 12 Sep 2017
The main goal of gene therapy is to replace a mutating gene that causes disease, with a healthy copy of the gene or inserting a new gene into the body to help fight the particular disease. In addition, gene therapy is a promising treatment option for a number of diseases such as inherited disorders, different types of cancer and viral diseases. (Samuel Murphy, 2008) Nonetheless, the technique is still under tests, for the reason that it stays risky. According to Professor Nathwani, there is no confirmation of any side effects in patients who already have been treated with gene therapy, still, long-term-follow-up for the adults patients is required before the therapy can be approved for children. Gene therapy is currently only being tested for untreatable diseases. The most challenging one for the gene therapy is Haemophilia. It is yet not accomplished, however there is a significant progress of improvement. (National Library of Medicine, 2016).
Haemophilia is a bleeding disorder resulted from low functional blood levels which slow down the blood thickening (clotting). Individuals with this condition experience prolonged bleeding during surgery, after a bad injury or even after they had a tooth pulled out. In very few cases of Haemophilia, prolonged bleeding occurs after minor trauma or in absence of any. In situations like this, bleeding into the brain, joints, or other internal organs could cause serious complications (National Library of Medicine, 2012).
Haemophilia overview, diagnosis and treatment options
There are two principle types of Haemophilia - A and B. Haemophilia A, additionally called, factor VIII, is a hereditary disorder caused by the absent or defective factor VIII (clotting protein). (National Haemophilia Foundation, no date). Haemophilia B, likewise, called factor IX (Christmas disease) is a hereditary disorder caused by the absent or defective factor IX (also a clotting protein), approximately 1/3 of the cases, in both types, are caused by a spontaneous change in a gene. The X and Y chromosomes are called sex chromosomes. The haemophilia gene is carried in the X chromosome. Males have XY chromosomes, X from their mother and Y from their father. Females have two X chromosomes, one from their mother and one from their father. In this case, if a boy has haemophilia gene in his X chromosome from his mother, he will have haemophilia. However, fathers cannot pass haemophilia to their sons. At the point when a female has haemophilia gene on only one of her X chromosomes, implies as a ''carrier'' and can only pass the disease to her children. (National Haemophilia Foundation, no date). Haemophilia is more common in males than females. Nowadays, 1 in 5000 males worldwide are born each year with Haemophilia A and approximately 1 in 20 000 with Haemophilia B.(National Library of Medicine, 2012). The most convenient way to diagnose Haemophilia is to find out if the disease is in the family history, then it would be very possible for the new-born to be infected as well. The other ways to diagnose the disease is to do blood tests to determine any missing clotting factors or low levels, and which ones are causing the problem, and DNA test, which is looking for mutations who cause the haemophilia and eventually compare it to the carrier (parents). The main treatment for haemophilia is called replacement therapy (gene therapy), involves injecting missing clotting factor proteins into the affected person's bloodstream. These proteins help to repair normal blood clotting but often the therapy must be repeated frequently (Hemophilia Federation of America, no date).
Gene therapy's future
Over the past 15 years an empowering data from successful trials on animals and humans have finally resulted incredible accomplishment in patients with severe Haemophilia A and B.
Researches from the University College London and St. Jude Children's Research Hospital organised a team to investigate a potential gene therapy improvement. The investigation was focused on 6 males with severe Haemophilia B. All patients received one-time intravenous infusions of the gene vector at different doses. As indicated by the review, the men were producing clotting factor IX at less than 1% of normal levels. After the gene therapy each patient was tested and the result showed a significant improvement - factor IX at between 2% and 11% of normal levels. According to the scientists, gene therapy would enhance the outcomes significantly more after proceeded regular therapy. (National Institutes of Health, 2011).
Most recently in 2016 another experiment took place, made by BioMarin. The case included 8 patients with severe form of Haemophilia A. The released information was demonstrated that 2 high dose patients had an increased levels of Factor VIII above 50 percent. Every one of the patients received a single dose of BMN 270 (new investigational drug), 6 of whom have been treated at the highest dose of 6x1013 vg/kg. The full treatment lasted up to four months. After the last observation, according to the researchers, the highest dose levels of experienced increasing Factor VIII ranged between 4 and 60 percent. All high dose patients had a significant improvement. Also, according to the World Federation of Haemophilia, factor levels were variating in the normal ranges. However, there was a slight problem with some of the patients. BioMarin noticed that some patients had expanded liver enzyme levels (because of the long period of the therapy), prophylactic corticosteroid therapy was given and according to the company, the enzyme levels dropped back to normal. (Ben Adams, 2016).
Third significant test included clinical trials managed by Professor Amit Nathwani of University College London and demonstrated an actual hope for haemophilia B patients. In this experiment, each patient received one of three doses of a gene therapy vector to deliver the genetic material for making Factor IX. Factor IX levels increased in all individuals with severe haemophilia B, the following gene therapy remained stable and lasted for more than 4 years. Amazing results and incredible improvement. Moreover, the six patients who received the highest gene therapy dose, remained high blood-clotting protein levels from less than one percent of normal to five or more, which reduced the spontaneous bleeding to 90 percent. According to Professor Nathwani, the unimaginable outcomes permitted the patients to live ordinary life and eventually practice their favourite sport without the need for Factor IX replacement therapy or any daily medication. (New England Journal of Medicine, 2011). The following graphs are showing the gained results from the experiment:
Figure 1. - Factor IX activity after gene transfer (The New England Journal of Medicine, 2014)
Figure 2. - Number of annual bleeding episodes (The New England Journal of Medicine, 2014)
Both of the graphs are demonstrating the improvement in each patient. Scientists do numerous trials, experiments and researches each day to develop the gene therapy technique. Many evidences of clinical efficacy are currently observed, more work is accomplished and more researches are made. Gene therapy has guaranteed the advantage to those who suffer from Haemophilia, however, this advantage has not been acknowledged yet due to the fact that this field is still young. Although, the majority of the taken experiments and their results are quite encouraging and for the past twenty years numerous trials demonstrated significant improvement in the patients (Christopher Doeing, 2009). Besides, the possibility of gene therapy treatment holds great hopes and has been successfully used to cure some diseases, however, the technique is still under research to make sure it will be safe and effective in the future with no life threatening side effects. It is believed that the gene therapy will lead to patients having rare bleeding episodes or even begin producing their own clotting factor. Therefore, more experiments have to be done and researches should take care for future side effects or inherited disorders (Mark Derewicz, 2015). All the recent examples of severe haemophilia and the incredible improved process toward a cure showed how much potential this technique has. Is it going to be the next treatment of choice? In my opinion, yes. The ability to insert a foreign gene into the body, and make it possible to approach a new treatment or the ability to control one of the most dangerous human diseases, is one of the first steps to complete success. According to Jack McCain, in 1990 Dr. Anderson carried the first gene therapy trial and cured a hereditary disease of the immune system in a 4-year-old-girl. Today, the patient is still alive and doing very well. This medical case along with the analyses stated above, prove that gene therapy one day can become a staple of 21st century medicine (Jack McCain, 2005).
According to Graham Templeton, gene therapy researchers have invested decades to develop this amazing technique. Nowadays, gene therapy can be life-changing for many people around the world. For the past 50 years new technologies have been used to control bleeding disorders, however gene therapy offers the possibility of a cure. As stated, gene therapy might be the next sensational discovery for a treatment not only for haemophilia but cancer, other inherited disorders or even HIV (Graham Templeton, 2016). For the past few decades scientists had some successful developments such as: discovering new treatments, inventing new techniques to investigate particular diseases, however the most important one is to be able to treat untreatable diseases, and according to all the experiments stated above, gene therapy is a promising technique, not only for correcting defects, but also for treating cancer and other harmful diseases. More work needs to be done before gene therapy can become a treatment of choice and this may take another decade until scientists are completely sure that there will be no harmful effects by choosing this technique as a possible cure of Haemophilia.
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