Gene Therapy - Whitt

Question 1

What is gene therapy?

Answer 1

An approach to treating disease based on modifying the expression of a person’s genes toward a therapeutic goal. Efficient in treating single gene deficiency disorders.

Question 2

Is gene therapy highly experimental?

Answer 2

Yes, it’s full potential has yet to be realized (Take Home Point 1)

Question 3

What was the first in vivo gene therapy?

Answer 3

Used an attenuated adenovirus for treatment of C.F.

Question 4

What is somatic gene therapy?

Answer 4

Manipulation of gene expression in cells in order to be corrective for the patient, non inherited

Question 5

What is germline gene therapy?

Answer 5

Genetic modifications that will pass down to the next generation (no current intent for human use)

Question 6

How would familial hypercholesterolemia be treated ex vivo in a patient’s liver?

Answer 6

Piece of liver removed and cells treated with retrovirus coding for LDL receptor gene, liver cells failing to take up retrovirus discarded, other ones reimplanted.

Question 7

What are some notable diseases undergoing trial? (Name a couple)

Answer 7

CF, MD, ADA, Sickle cell anemia, OTC def, LPL def, PKU, Hemophelia, HIV, Rheumatoid Arthritis, Head and neck tumors, Prostate, breast, and colon cancer, Diabetes, CAD

Question 8

What is the goal of viral infection treatment? What phase of HIV is the treatment targeted at?

Answer 8

For latent and long lasting viruses; during the latent asymptomatic phase.

Question 9

What is the goal of therapy in cancer?

Answer 9

To remove tumor cells, not to correct them.

Question 10

True or False. There are no FDA approved gene therapy products currently on the market in the US.

Answer 10

True (take home point 2)

Question 11

What are the two types of intervention strategies for gene therapy applications?

Answer 11

Therapeutic strategies and Cytolytic strategies

Question 12

What is the therapeutic strategy?

Answer 12

Vector carries a gene that encodes a protein that is either defective or that is not present (adenovirus injected w/ CFTR in CF patients)

Question 13

What is the cytolytic strategy?

Answer 13

Vector designed to destroy or eliminate a diseased cell or tissue. Used in cancer.

Question 14

What are the 4 requirements/challenges for gene therapy?

Answer 14

1) Gene identification and cloning
2) Delivery
3) Elements to ensure controlled gene expression
4) Understanding the host immune response

Question 15

Gene ID and cloning has become easier since what?

Answer 15

Human Genome Project

Question 16

True or False. Delivery is the greatest challenge.

Answer 16

True; must be specific, efficient, and safe.

Question 17

Most vectors are attenuated or modified versions of the virus for what purpose?

Answer 17

To remove the disease causing components and insert recombinant genes that will be therapeutic.

Question 18

What strategies for delivery use non-viral vectors?

Answer 18

Liposome transfection and “Gene gun” technology

Question 19

What is the goal of understanding the host response?

Answer 19

Minimal adverse effects because multiple doses are usually needed

Question 20

What are the 5 types of vectors?

Answer 20

Adenoviruses, Adeno-associated viruses, Herpesvirus, Liposomes/Naked DNA, Retroviruses

Question 21

What are Adv/Disadv of Adenovirus?

Answer 21

Episomal, High transduction efficiency, Infects replicating and non replicating cells, elicits an immune response, insert capacity 8-36kb

Question 22

What are the adv/disadv of adeno-associated virus?

Answer 22

Integrates genome into specific region on human chromosome 19, low immunogenicity, no associated disease, infects both dividing and non dividing cells, limited insert capacity of ~5kb.

Question 23

What are the Adv/Disadv of herpes virus?

Answer 23

Large insert capacity, broad host range, infects dividing and non dividing cells.

Question 24

What are the Adv/Disadv of liposomes/naked DNA?

Answer 24

No limit to size of genes, low immunogenicity, poor levels of gene transfer

Question 25

What are the adv/disadv of retrovirus?

Answer 25

Non-pathogenic in humans, stably transduces dividing cells but not non dividing, inserts genome into host cells DNA, long term expression, insert capacity of 8 kb, inactivated by human complement

Question 26

What are the 2 most common vectors mainly being used in trials?

Answer 26

Adenoviruses and Retroviruses

Question 27

What three boards must gene therapy trials get approval from?

Answer 27

Internal Review Boards
FDA
Recombinant DNA Advisory Committee (RAC)

Question 28

What are the 3 questions that must be answered before gene therapy can become available as a true therapeutic tool for physicians?

Answer 28

How to avoid immune response?
How to get genes into non-dividing cells like liver, muscle, and neurons?
How to get gene integrated so that it will be replicated and expressed indefinitely?

Question 29

What immune responses can vectors evoke?

Answer 29

Inflammation (Serious problem with adenoviruses), antibodies to destroy the vector when administered again

Question 30

How to get genes into non-dividing cells is a problem of what?

Answer 30

The vector used; specific targeting of cells still remains a big problem

Question 31

How does adeno-associated virus (AAV) get its name?

Answer 31

Often found in cells that are simultaneously infected with adenovirus.

Question 32

Unlike some gene therapy vectors, AAV: (4 things)

Answer 32

Does not stimulate inflammation
Does not elicit Ab’s against itself
Can enter non-dividing cells
Integrates successfully into one spot on the genome of its host (chromosome 19)

Question 33

True or False. Patient therapy is of paramount importance and all possible efforts must be made to minimize risk?

Answer 33

True, take home point 3

Question 34

What are the 5 factors that will influence development of gene therapy in the future?

Answer 34

Optimizing vector safety to reduce adverse event risk
Overcoming technological obstacles
Additional Human Genome analysis
Expansion of the diagnostic industry
Reducing risk through public acceptance of gene therapy