1. GENE THERAPY
By Sam Lai and Meng Lee

2. Gene Therapy Introduction : What is it? Gene Therapy : A Closer Look
How much did you learn?!
Case Study : SCID
Model for Gene Therapy Medical Framework
Discussion / Q&A

3. What is it?
Gene therapy, which was first conceived in the mid-1970s, aims to insert working copies of genes into cells containing dysfunctional ones
treat, cure, or ultimately prevent disease by changing the expression of a person's genes
current gene therapy is primarily experimental, with most human clinical trials only in the research stages
Most often in context of treating lethal and disabling diseases, potential also for disease prevention

5. Human Genome Project
A genome is all the DNA in an organism, including its genes. Genes carry information for making all the proteins required by all organisms
Variations in structure of person’s genes collectively helps define us as individuals
Rationale for GT is based on knowledge of the human genetic code
Began formally in 1990, set as a 13 year project.

6. HGP GOALS Identify aproximately 30,000 genes
Determine 3 billion chemical base pairs that make up human DNA
Store information in databases
Improve tools for data analysis
Address ethical, legal and social issues that might arise from this

7. HGP cont…
Achieve these goals, researchers look at genetic makeup of other organisms
This project is important because the government's dedication to the transfer of technology to the private sector

9. Which Cells Targeted?
somatic gene therapy the recipient's genome is changed, but the change is not passed along to the next generation
germline gene therapy, the sex cells are changed with the goal of passing these changes to their offspring. But, this is not being actively investigated, at least not humans, although a lot of discussion is being conducted about its value and desirability.

10. Somatic Stem Cells Somatic stem cells are remarkable cells in the body
These different stem cell types are targets for gene therapy
Genetically treated stem cells, when reintroduced into the patient's body are expected to naturally travel through the blood stream to the bone marrow.

11. Germline Gene Therapy
Gene therapy in germline cells has the potential to affect not only the individual, but also their children as well.
Any genetic changes in the reproductive cells or changes made to the embryo before the stage of differentiation, would affect all future offspring of that person. This makes an vital distinction, affecting major ethcial issues

12. Delivery of Genes
Need an efficient method to deliver the gene to live cells.
Done via vectors (gene carriers), delivering therapeutic genes to cells - common vector is viruses
Alternative delivery methods seen with use of lipids and proteins

13. Use of Viruses
Viruses evolved a way of delivering their genes to human cells in pathogenic matter.
Take advantage of this, manipulate genome to remove disease genes and insert therapeutic genes

15. Risks with GT trials
Viruses can usually infect more than one type of cell.
When DNA is injected directly into a tumor, there is a slight chance that this DNA could unintentionally be introduced into reproductive cells.
Other concerns include the possibility that transferred genes could be "overexpressed"

17. Add a new chromosome?
Experimentation seen with introduction of 47th chromosome
Exist along 46th chromosome, large vector capable carrying genetic code, that hopefully the immune system would not attack

19. Understanding?
Scientists know little about function of the thousands of genes. Attempting therapy without this knowledge would address few genes of a particular disease
i.e. Sickle Cell Anemia

20. Sickle Cell Anemia
Caused by error in gene that informs our body on how to make hemoglobin
Prevalent in African Americans
However deadly the error is, this increased the survival rate for those who also had malaria in the region

21. Hurdles…
Most genetic disorders involve more than one gene, only few genetic diseases involve merely one
This multigene disorders also involve the environment, such as diet, exercise, smoking, etc.

23. Everything has a price
High costs associated with developing this technology, and regulations that needed to be implied on it with experimentations are great hurdles for experimenters in this field.

24. First Human Gene Therapy attempt
Began in 1990, using ex vivo strategy, where patient cells were cultivated in laboratory and incubated with vectors
transplanted back into the patient
Attempted to treat 2 genetic disorders, including children with immune defiency as well as people with high levels of serum cholesterol

25. First Human GT cont…
Practical approaches, delivering genes based on so-called in vivo GT where viruses are directly given to patients
First model was dependent on a version of adenovirus to treat cystic fibrosis

26. GT on Cancer Treatment
Researchers are working to improve the body's natural ability to fight the disease or to make the cancer cells more sensitive to other kinds of treatment, such as chemotherapy
Substitution of a "working" copy of a gene for an inactive or defective gene.

27. GT on Cancer cont…
Injection of cancer cells with a gene that makes them more sensitive to treatment with an anticancer drug.
Introduction of the multidrug resistance gene into stem cells. The MDR gene is used to make the stem cells more resistant to the side effects of the high doses of anticancer drugs.

28. Hurdles Summary
There are many obstacles that prevent researchers and scientist from developing successful gene therapy techniques.
The issues being confronted are the same ones that are faced whenever a powerful new technology is developed.

29. When All is Said…
A proposed gene therapy trial, or protocol, must be approved by at least two review boards at the scientists' institution.
Any studies involving humans must be reviewed with great care.

30. CASE STUDY: SCID
SCID = Severe Combined Immunodeficiency

31. What is SCID? SCID patients can neither
Construct cell-mediated immune response
Make Antibodies
Patients do not die of SCID itself
More Boys than Girls

32. SCID Cases, Past & Present
Not discovered until early 1960s
Occur in 1 out of 1.000,000
“Bubble Boy” – David Vetter
Spent 12 years in Texas Hospital Sterile Tent
Usually not discovered until too late

33. Science Behind SCID (1) What Happens in SCID
Lymphocyte T & B cells do not get developed
Normal catabolism of purines deficient
Body lack messenger to identify foreign bodies
Cannot initiate immune response

34. Science Behind SCID (2) What Caused SCID?
ADA (Adenosine Deaminase) enzyme deficiency
Autosomal recessive inheritance of genes coding for ADA (25%)
Cannot Make T cells
Spontaneous Mutation of IL-7 Gene

35. Science Behind SCID (3)

36. Science Behind SCID (4)

37. Possible Therapies Gem free tent (life long)
Regular injections of PEG-ADA
Bone Marrow Transplant
Gene Therapy

38. GT Curing SCID (1) How mutated genes were discovered?
Late 1970s – understood mechanism for immune system
Match SCID to missing enzyme
Brute force / luck
1983 – ADA cDNA identified & cloned

39. GT Curing SCID (2) How mutations are corrected
Recombinant DNA technologies!!!
Gene Splicing
Insertion of correct gene into retrovirus vector
Separate & Multiply
Insert into patient

40. GT Curing SCID (3) How to decide on delivery mechanism? Goals:
Must take up long-term residence in patient
Must be expressed adequately
Methods:
1990 – use patient’s own T cells (ADA)
1993 – use blood stem cells (ADA)
1999 – use blood stem cells (X-linked IL-7)

41. GT Curing SCID (4) Gene Therapy Successes
So far approximately 80% success rate
Restoration of normal cellular immunity in patients
Blood Stem Cells Method done on an increasing scale

42. SCID Cure Analysis Why GT works in SCID? Defect at a single gene locus
Genes identified & cloned
Undergo irradiation or immunosuppressive chemotherapy
Treatment of young children

43. Discussion of Ethical, Legal & Social Issues
Many issues & concerns, little answers
Real life solutions come from idea brainstorms
Today: Sample Medical
System Framework

44. Current Development Signs of Development
State Laws & Federal Bills which prohibits discrimination based on genetic information
Special committee reviewing gene therapy (NIH + FDA)
3-5% of all funds for genetics studies must be used for investigation of such issues

45. Targeted Issues Regulation of Gene Therapy
Assurance of Quality of Treatment
Targeted Treatment
Disease Treatment vs. Enhancement
Only Disease Treatment
Fair & Readily Available Treatment
Same Treatment for everyone
At an affordable price
Protection of Genetic Information

46. Assumptions
Possible to isolate and provide treatment only for disease alleles without committing enhancement
Development in medical technologies will make medication cheaper in the long run
Model applies for a closed country only

47. Model Philosophy
Possession of genetic information causes many problems
Must have a tightly regulated system in place (multi-level, multi-group)
Proposal
Central Gene Therapy Monitoring Administration

48. Structure of Medical System
3 Levels, 5 Groups
Government: CGTMA Review Committee
Practitioners: Doctors Gene Therapeutics
Patients: Patients

49. Patient Treatment Process (1)
7 Steps
Disease Identification
1.1 Doctor Identifies Genetic Problem
Application for Treatment
2.1 Doctor Submit Application
Treatment Approval
3.1 CGTMA Reviews Application

50. Patient Treatment Process (2)
Preparation of Delivery Material
4.1 Gene Therapeutics cure the disease genes, deliver to patient’s stem cell
Confirmation of Appropriate Changes
5.1 CGTMA confirms for appropriate changes
Gene Therapy
6.1 Doctor conducts Gene Therapy to Patient

51. Patient Treatment Process (3)
Checkup
7.1 Confirm patients received only approved treatment (by CGTMA)

52. Groups Responsibility (1)
CGTMA
Check validity of genetic treatment (i.e. only targeting disease genes)
Check for appropriate preparation of genetic material for gene therapy
Monitor Treatment by Doctor
Review Committee
Determine disease genes vs. enhancement genes

53. Groups Responsibility (2)
Doctors
Identifying Disease
Submitting Application for Gene Therapy
Conducting Gene Therapy
Gene Therapeutics
Manipulate genes based on application
Both group faces penalty for illegal practices

54. Important Factors
Must have good internal and external monitoring by each group
Must be aware and implement policy for patient’s privacy rights
Education of the general public

55. Discussion + Q&A How model answers targeted issues
Flaws with the models
Discussion
Additional Q&A

56. End (Yeah finally…)
Thanks for your patience !