Gene Therapy

Question 1

What is the definition of Gene Therapy?

Answer 1

The deliberate introduction of genetic material into human somatic cells (a cell that is non-germ line) for therapeutic prophylactic or diagnostic purpose

It is the ADDITION of EXTRA genes
- NOT precise, targeted correction of genetic defects (alteration of existing genes)

Question 2

What is the aim of Gene Therapy?

Answer 2

• Cure disease

- Improve the clinical status of a patient

Question 3

What is a human somatic cell?

Answer 3

A cell that is non germ-line.

Germ line gene therapy is considered unethical and prohibited

Question 4

Why are vectors necessary for the delivery of genes?

Answer 4

• DNA is a big molecule and it can be difficult to target the exact site.
• It is also difficult to get genes into cells.

We need to utilise vectors in order to deliver the genes into the cells (specifically the nucleus)

Question 5

What are the main Gene Therapy Strategies?

Answer 5

1. Gene Replacement
   - Replace ‘faulty’ genes with normal genes
   - Corrects inherited genetic errors
   - Provides a missing function
   - Monogenic diseases e.g. cystic fibrosis, haemophili etc
2. Gene Addition
   - Delivers genes to provide a new function
   - Polygenic diseases e.g. cancer

Question 6

The perfect vector is…

Answer 6

Easy & Cheap Production
Targeted
High Gene Expression
Regulation of Expression
No adverse/pathogenic effects

Question 7

What are the main types of non-viral vectors?

Answer 7

• Naked DNA
• Lipoplexes
  
  • > Liposomes/DNA
• Polyplexes
  
  • > Polymer/DNA
• Lipopolyplexes
  
  • > Liposome/Polymer/DNA

Question 8

What are the main types of viral vectors?

Answer 8

DNA Viruses

• Adenovirus
• Adeno-associated virus
• Herpes simplex virus

RNA Viruses

• Lentivirus
• Retrovirus

RNA viruses tend to insert their genes into genome. DNA Viruses tend to have transient effects

Question 9

What is Ex Vivo Gene Therapy?

Answer 9

• Remove ‘faulty’ cells from patient
• Transfect cells with therapeutic gene (outside the body)
• Return cells to patient

Question 10

What is In Vivo Gene Therapy?

Answer 10

• Systemic infusion (of DNA liposome)
• Tissue injection (of Recombinant virus)
• and Biolistic gene gun insertion (of plasmids)

Question 11

Which regulations govern the handling of gene therapy vectors

Answer 11

Non-viral vectors
- No additional regulations

Viral vectors

• GMO (Contained Use) Regs 2014, HSE
  
  • > All possible barriers (physical, biological or chemical) are in place to limit contact of the GMOs with humans and the environment
• GMO (Deliberate Release) Regs 2002, DEFRA
  
  • > All appropriate measures are taken to avoid damage to the environment from the escape or release from human control of GMOs

Question 12

Protection of Human Health & the Environment EXCLUDE or INCLUDE? Product &/or Patient Safety

Answer 12

Exclude

Question 13

What additional regulations apply to gene therapy clinical trials?

Answer 13

Gene Therapy Advisory Committee (GTAC)

• UK ethics committee for gene therapy
• Patient flagging and long term monitoring
• Provide advice to health ministers
• Applies to ALL gene therapy clinical trails using viral AND non-viral vectors

Question 14

The handling of GMOs in Pharmacy includes…

Answer 14

• Risk assessment
• SOPs
• Storage
• Clinical screening
• Dispensing
• Documentation
• Transportation
• Accidental exposure