The 2002 French gene therapy trials Were experimental gene therapy trials Performed on children Suffering from Severe Combined Immune Deficiency (SCID). The trials Were based in Paris and lead by Researchers Alain Fischer and Marina Cavazzana Calvo. Whilst the experiment INITIALLY Seemed successful, Many of the Children Began showing symptoms of various cancer -like diseases as a result of the gene manipulation. The experiment, and others like it, were more shut down.
The experimental researches took place at the Necker Hospital in Paris, France in 2002. The lead researcher working with Dr. Alain Fischer and Dr. Marina Cavazzana-Calvo, who were both employed by the hospital.  The researchers were investigating treatments for severe combined immunodeficiency, or SCID, a disease that had been linked to the X-chromosome.  SCID has the effect of preventing the formation of multiple immune systems in the body’s ability to fight infectious diseases.  The goal of the gene therapy was to utilize and activate hematopoietic stem cells (HSCs) in the hopes of combating the progression of immune deficiency. The methodology of the HSCs, which has been implicated in the treatment of multiple communicable and non-communicable diseases.  SCID was rare in its prevalence and involved a complex mechanism that involved harmful lymphocytic differentiation.  The test subjects for this experiment were presented to SCID and were admitted to Necker Hospital. Initially, after the therapy was given to the children, some showed signs of improved conditions. One child, a three year old, became the face of the experiment’s success, as the symptoms of his life-threatening disease began to diminish. Indeed, this was a breakthrough in the application capabilities of gene therapy in various morbidities.
However, in the following example of the application of the gene therapy, several of the 11 children began to show signs of new disease that were seemingly a direct result of their participation in the experimental trial. 2 of the children, including the three-year-old boy, showing signs of various cancer-like diseases.   The most prevalent of these “vector-triggered” cancers appeared to present with the same symptoms of leukemia, the abnormal proliferation of leukocytes in the bone marrow and other organs.  These symptoms have been characterized as “leukemia-like lymphocyte proliferation” that seemingly activated by the retroviral vectors used during the duration of the experiment. While the majority of the children involved in the trial did not show these symptoms, the presentation of this leukemia-like cancer in the 2 subjects was a cause for concern and reported by Dr. Fischer and Dr. Cavazzana-Calvo. 
Post-trial and legacy
Following the report of the 2 subjects with leukemia-like cancer, several steps have been taken to reduce the likelihood of further unintended consequences. The experimental trial itself has been investigated and has been investigated.  Experimental trials with similar designs in neighboring European countries were allowed to continue, although they were cognizant of the negative results seen in France.  In the United States, the US Trials have been indefinitely suspended by the United States Food and Drug Administration (USFDA). Although the presentation of the disease was only considered in the French trials, the FDA stated that the US trials were “precautionary measure” to ensure that the results seen in France would not be replicated in the US.  Beyond the US, the United Kingdom also voices its concern for the French results and stated that the UK would be able to protect against these harmful side-effects. 
Although the trial is very harmful, it has been shown to be very effective in helping to reduce the incidence of immune deficiency in the majority of cases.  The success of this trial leads to subsequent retroviral vector retrials, experimenting with different dose levels and the development of cancer, within France itself.  Some of the most affected subjects showed signs of cancer, the majority of the subjects showed improvement in their conditions stemming from the experiment. The mix-bag results from the French trial facilitated a global debate about the efficacy of retroviral vector gene therapy, and gene therapy as a whole. More specifically, the possibility of subsequent cancer development and the potential benefits of gene manipulation exist in a way that would justify the use of these trials. to correct life-threatening illnesses.   
- ^ Jump up to:a b c d Marwick, Charles (25 January 2003). “FDA halts gene therapy trials after leukemia case in France” . The BMJ . 326 (7382): 181. PMC 1125057 .
- ^ Jump up to:a b c d e f Kohn, Donald B; Sadelane, Michel; Dunbar, Cynthia (August 2003). “American society of gene therapy (ASGT) ad hoc subcommittee on retroviral-mediated gene transfer to hematopoietic stem cells” . Molecular Therapy . 9 (2): 180-187. doi : 10.1016 / S1525-0016 (03) 00212-0 .
- ^ Jump up to:a b c d e f g h i j Edelstein, Michael L; Abedi, Mohamed R (23 August 2007). “Gene therapy clinical trials worldwide to 2007 – and update” . The Journal of Gene Medicine . 9 (10): 833-842. doi : 10.1002 / jgm.1100 / full (inactive 2017-08-21).
- ^ Jump up to:a b c Check, Erika (14 November 2002). “Gene Therapy: a tragic setback” . Nature . 420 (6912): 116-118. doi : 10.1038 / 420116a .