1. Dr. Peter John M.Phil, PhD Atta-ur-Rahman School of Applied Biosciences (ASAB) National University of Sciences & Technology (NUST)

2. Gene Therapy GT Data worldwide Classical & Non Classical
Disease Selection for GT
Barriers to successful gene therapy
GT for Monogenic disorders
Examples of GT

3. GT Clinical Trials (2012)

4. Clinical Trials by Disease Categories (2012)

5. Delivery Vectors

6. Targeting of different organs by viral vectors

7. Major Types GT
Classical Gene Therapy
Non Classical Gene Therapy

8. Classical gene therapy
Classical gene therapy is the approach which delivers genes to the appropriate target cells with a goal of attaining optimal expression of the new, introduced gene.
Once inside the patient, the expressed genes are intended to: produce a product that the patient lacks, kill the diseased cells directly by producing a toxin, and activate the immune system to help the killing of the diseased cells.

9. Classical GT Approach
This approach involve to deliver gene into targeted cell.
Produce a product that a patient lack
Kill the disease directly by producing toxin
Activate immune system

10. Non classical Gene Therapy
Non classical gene therapy inhibits the expression of genes related to pathogenesis, or corrects a genetic defect and restores normal gene expression.

11. Non Classical GT Approach
This approach involve to inhibit the expression of genes.
To correct the genetic defect and to restore the normal gene expression

12. Why GT ?
Many diseases have still not cure & require expensive treatments to prolong the life spam of patients.
The idea that therapeutic gene transfer may permanently cure some diseases.

13. Long term expression Stable and long-term expression of the protein
Localized to the injection site
possibility of targeting specific cell populations (with aid of cell-type specific promoters or modifying viral coat proteins
Continuous supply of the protein of choice

14. Patient’s Own Cell
In gene therapy, the patient’s own cells are used to cure the disease. Hence their will be no rejections (immunologically) by the patient’s body.
Brain cells which are hard to target by traditional therapies, can be easily targeted using lentiviral vectors in gene therapy.

15. Permanent cure The cure is permanent for the patients life time.
The genetic manipulation can only done in the somatic cells of the patient and hence there is no risk to the future generations.
Even dangerous diseases like AIDS, SCID, Thalassemia can be cured by gene therapy.

16. Genetic Disorders
Thus there is a chance for permanent cure of neurological disorders.
Today, gene therapy is a medical necessicity in many types of diseases including cancer and genetic disorders.

17. A disease suitable for GT
Over 4000 diseases results for single gene disorders
Many single gene disorders are due to mutations in nucleic acid sequence.
In some case a protein is abnormal & is recognized as non-self.
This elicit immune response & cause autoimmune disease.

18. A disease suitable for GT
In some cases the mutant protein may have regulatory role, like p53.
P53 is involved in 50% cancers
P53 play a role is arresting the cell growth/in apoptosis

19. A disease suitable for GT
A disease may be suitable if its life threatening.
The effect of the disease must be potentially reversible by the treatment
The gene must be fully characterize.
The targeted site be feasible.
Then its ethically acceptable for GT treatment

20. Benefits for single gene disorder GT
Life saving of the patients
Reduce the cost of managing the disease
High GT cost per annum could be acceptable

21. Major Monogenic disorders
Familial Hypercholesterolemia.
Polycystic kidney disease
Huntington’s Chorea
Cystic Fibrosis
Haemophilia
Phenylketonuria
Duchene Muscular Dystrophy

22. Strategy for transfer of gene

23. Barriers to successful gene therapy
Vector development
Corrective gene construct
Proliferation and maintenance of target cells
Efficient transfection and transport of DNA to nucleus for integration into genome
Expansion of engineered cells and implantation into patient

24. Cystic Fibrosis Autosomal Recessive disorder.
Abnormal Electrolyte transport in epithelial cells
The disease cause respiratory failure
Mutation in the gene CFTR (cystic fibrosis transmembrane conductor regulator) have been pinpointed.
Patient don’t survive in their mid-thirities.

25. GT trials for Cystic Fibrosis
Several trials have been carried out delivering CFTR gene encoded in adenoviruses.
The result of phase-1 study showed 30% improvement over a two week period without any side effect in 2 of 3 patients.
The 3rd patient showed inflammatory response to adenovirus vector.
Further studies are going on.

26. Adenosine deaminase deficiency
ADA cause sever combined immunodeficiency.
Disease cause by ADA enzyme deficiency that result in elevated level of dATP blocking T-lymphocyte differentiation in the thymus.

27. GT for ADA Current therapies include bone marrow transplantation
Or supplement of ADA

28. Familial Hypercholesterolemia (FH)
In this case the arteries become thickened and eventually blocked.
The patient can suffer angina and acute myocardial infarction.
The disease also treated with by pass or angioplasty.
The draw back is it require general anaesthesia & is not an easy process.

29. GT for FH FH result from LDL receptor
This cause high LDL level in the blood while HDL is suppressed.
Phase-1 clinical trial is underway.
Patient hepatocytes isolated, then transduce ex-vivo with a retrovirus expressing LDL receptors.
The modified cell reinfused into inferior mesenteric vein.

30. GT for FH One patient showed decrease in serum cholesterol level
Improvement in LDL:HDL ratio.

31. Cancer Lungs Cancer Breast Cancer Colorectal cancer
Malignant Lymphoma, myeloma
Leukemias
Ovarian

32. General Treatments Surgical Radiotherapy Chemotherapy
Success rate/Problems:
If tumor retained within the treatment area.
Inability to differentiate b/w normal & affected cells

33. GT for Cancer GT provide an alternative route. Problems in cancer GT
To target the therapeutic gene to every tumour cell.

34. Cancer GT Strategies Gene Augmentation Therapy (GAT)
Antisense Oligonucleotides
Targeted Killing of specific Cells
Immunotherapy
Targeted Mutation Correction
Targeted Inhibition of gene expression

35. The End