| Subject: :Centennial Promise: |
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Novalogic
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Date Posted: 10:59:01 12/12/03 Fri
Hi!
Another major blow came in January 2003, when the FDA placed a temporary halt on all gene therapy trials using retroviral vectors in blood stem cells. FDA took this action after it learned that a second child treated in a French gene therapy trial had developed a leukemia-like condition. Both this child and another who had developed a similar condition in August 2002 had been successfully treated by gene therapy for X-linked severe combined immunodeficiency disease (X-SCID), also known as "bubble baby syndrome."
FDA's Biological Response Modifiers Advisory Committee (BRMAC) met at the end of February 2003 to discuss possible measures that could allow a number of retroviral gene therapy trials for treatment of life-threatening diseases to proceed with appropriate safeguards. FDA has yet to make a decision based on the discussions and advice of the BRMAC meeting.
What factors have kept gene therapy from becoming an effective treatment for genetic disease?
Short-lived nature of gene therapy - Before gene therapy can become a permanent cure for any condition, the therapeutic DNA introduced into target cells must remain functional and the cells containing the therapeutic DNA must be long-lived and stable. Problems with integrating therapeutic DNA into the genome and the rapidly dividing nature of many cells prevent gene therapy from achieving any long-term benefits. Patients will have to undergo multiple rounds of gene therapy.
Immune response - Anytime a foreign object is introduced into human tissues, the immune system is designed to attack the invader. The risk of stimulating the immune system in a way that reduces gene therapy effectiveness is always a potential risk. Furthermore, the immune system's enhanced response to invaders it has seen before makes it difficult for gene therapy to be repeated in patients.
Problems with viral vectors - Viruses, while the carrier of choice in most gene therapy studies, present a variety of potential problems to the patient --toxicity, immune and inflammatory responses, and gene control and targeting issues. In addition, there is always the fear that the viral vector, once inside the patient, may recover its ability to cause disease.
Multigene disorders - Conditions or disorders that arise from mutations in a single gene are the best candidates for gene therapy. Unfortunately, some the most commonly occurring disor ders, such as heart disease, high blood pressure, Alzheimer's disease, arthritis, and diabetes, are caused by the combined effects of variations in many genes. Multigene or multifactorial disorders such as these would be especially difficult to treat effectively using gene therapy. For more information on different types of genetic disease, see Genetic Disease Information.
What are some recent developments in gene therapy research?
University of California, Los Angeles, research team gets genes into the brain using liposomes coated in a polymer call polyethylene glycol (PEG). The transfer of genes into the brain is a significant achievement because viral vectors are too big to get across the "blood-brain barrier." This method has potential for treating Parkinson's disease. See Undercover genes slip into the brain at NewScientist.com (March 20, 2003).
RNA interference or gene silencing may be a new way to treat Huntington's. Short pieces of double-stranded RNA (short, interfering RNAs or siRNAs) are used by cells to degrade RNA of a particular sequence. If a siRNA is designed to match the RNA copied from a faulty gene, then the abnormal protein product of that gene will not be produced. See Gene therapy may switch off Huntington's at NewScientist.com (March 13, 2003)
New gene therapy approach repairs errors in messenger RNA derived from defective genes. Technique has potential to treat the blood disorder thalassaemia, cystic fibrosis, and some cancers. See Subtle gene therapy tackles blood disorder at NewScientist.com (October 11, 2002).
Gene therapy for treating children with X-SCID (sever combined immunodeficiency) or the "bubble boy" disease is stopped in France when the treatment causes leukemia in one of the patients. See 'Miracle' gene therapy trial halted at NewScientist.com (October 3, 2002).
Researchers at Case Western Reserve University and Copernicus Therapeutics are able to create tiny liposomes 25 nanometers across that can carry therapeutic DNA through pores in the nuclear membrane. See DNA nanoballs boost gene therapy at NewScientist.com (May 12, 2002).
Sickle cell is successfully treated in mice. See Murine Gene Therapy Corrects Symptoms of Sickle Cell Disease from March 18, 2002, issue of The Scientist.
What are some of the ethical considerations for using gene therapy?
--Some Questions to Consider...
What is normal and what is a disability or disorder, and who decides?
Are disabilities diseases? Do they need to be cured or prevented?
Does searching for a cure demean the lives of individuals presently affected by disabilities?
Is somatic gene therapy (which is done in the adult cells of persons known to have the disease) more or less ethical than germline gene therapy (which is done in egg and sperm cells and prevents the trait from being passed on to further generations)? In cases of somatic gene therapy, the procedure may have to be repeated in future generations.
Preliminary attempts at gene therapy are exorbitantly expensive. Who will have access to these therapies? Who will pay for their use?
Gene Therapy Links
General Information
MEDLINEplus: Genes and Gene Therapy - Access news, information from the National Institutes of Health, clinical trials information, research, and more.
Recombinant DNA and Gene Transfer - National Institutes of Health Guidelines
Questions and Answers about Gene Therapy - A fact sheet from the National Cancer Institute.
Introduction to Gene Therapy - An overview by Access Excellence.
A Gene Therapy Primer - Introduction to gene therapy from the bio.com.
Gene Therapy and Your Child - From KidsHealth for Parents.
Pioneering gene treatment gives frail toddler a new lease of life
Gene Transfer - An overview of gene therapy science issues, ethical concerns, and regulation and policy from the Genetics & Public Policy Center.
Cures - An introduction to gene therapy provided by discoveryhealth.com.
Delivering the Goods - An article describing the different types of gene therapy approaches. From October 2, 2000, issue of The Scientist.
How to Turn on a Gene - An article from Wired Magazine.
How Viruses Are Used in Gene Therapy - From The DNA Files, a series of radio programs from SoundVision Productions.
Human Gene Therapy: Present and Future - A Human Genome News article.
Human Gene Therapy - Access background and historical information, religious and philosophical issues, public policy, and additional readings on gene therapy. From the Georgetown University National Reference Center for Bioet hics Literature.
Gene Therapy - A NewsHour with Jim Lehrer transcript covering the death of gene therapy patient, Jesse Gelsinger (February 2, 2000).
Animations from the Tokyo Medical University Department of Paediatrics Genetics Study Group
Animations of Induction of Genes (Gene Therapy)
Animations of Problems in Gene Therapy
FDA Information
FDA Advisory Committee Discusses Steps for Potentially Continuing Certain Gene Therapy Trials That Were Recently Placed on Hold - 2/28/2003
FDA Places Temporary Halt On Gene Therapy Trials Using Retroviral Vectors In Blood Stem Cells - 1/14/2003
New Initiatives to Protect Participants in Gene Therapy Trials - 3/7/2000
Human Gene Therapy and The Role of the Food and Drug Administration - An overview from the Center for Biologics Evaluations and Research of the U.S. Food and Drug Administration.
Human Gene Therapy Harsh Lessons, High Hopes - An article published in the September-October 2000 issue of FDA Consumer magazine.
The Last Word: Researchers React to Gene Therapy's Pitfalls and Promises - An article published in the September-October 2000 issue of FDA Consumer magazine.
Fundamentals of Gene Therapy - Diagrams and basic description of gene therapy from the FDA.
Gene Therapy Ethics
Ethical Issues in Human Gene Therapy - A Human Genome News article.
Special Report: Ethics of Genetics - From Guardian Unlimited.
Ethical Issues in Human Gene Therapy - A Human Genome News article.
Gene Therapy Clinical Trials
University of Pittsburgh Molecular Medicine Institute - Contains information about ongoing and completed clinical trials.
Gene therapy studies in ClinicalTrials.gov - The U.S. National Institutes of Health resource for public access to information on clinical research studies.
Gene Therapy Clinical Trials - Access to a worldwide database of gene therapy clinical trials at this Web site from the publishers of The Journal of Gene Medicine. To search the database, click on "Interactive Database" at the top of the page. Access to charts, statistics, and abstracts from clinical trials results also provided.
Professional Associations
American Society of Gene Therapy
Australasian Gene Therapy Society (AGTS)
European Society of Gene Therapy (ESGT)
The Japan Society of Gene Therapy (JSGT)
Gene Therapy Journals
(Scientific, peer-reviewed publications targeted to clinicians and researchers. Access to full-text articles in these journals typically requires a subscription.)
Cancer Gene Therapy - From the publishers of Nature.
Current Gene Therapy - From Bentham Science Publishers.
Gene Therapy - From the publishers of Nature.
Human Gene Therapy - Journal published by Mary Anne Liebert, Inc.
The Journal of Gene Medicine - Official journal of the European Society of Gene Therapy (ESGT), Japan Society of Gene Therapy (JSGT), and the Australasian Gene Therapy Society (AGTS).
Molecular Therapy - A monthly journal published by the American Society of Gene Therapy (ASGT).
Other Publications
Vector - Magazine of the Gene Therapy Center at the University of Alabama at Birmingham. Issues available for download as PDF.
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