The deliberate introduction of genetic material into human somatic cells for therapeutic, prophylactic or diagnostic purposes
Addition of EXTRA genes
Aim is to cure disease (or at least help the patient)
First introduction of gene-modified cells into a patient was in 1989
First gene therapy product approved for market in 2004
Still very experimental and early in its development
PTQA April 2008
Gene Therapy Vectors
Vectors deliver genes to cells
Therapeutic gene (Transgene) Therapeutic protein Vector for efficient gene delivery Transcription Translation
Types of Gene Therapy Vectors
Non-viral vectors
Naked DNA
Liposomes/DNA
Polymer/DNA complex (polyplex)
Liposome/Polymer/DNA (lipopolyplex)
Viral vectors
DNA viruses
Adenovirus
Herpes Simplex Virus
RNA viruses
Retrovirus
Gene Therapy Strategies
Gene Replacement
Replace ‘faulty’ genes with normal genes
Corrects inherited genetic errors
Provides a missing function
Monogenic diseases e.g. cystic fibrosis, haemophilia, X-SCID
Gene Addition
Delivers genes to provide a new function
Polygenic diseases e.g. cancer
Were trying to make a mouse contraceptive vaccine for pest control
Used modified mousepox virus as vehicle for transporting antibodies into mice
Inserted gene to create ↑ IL-4 (interleukin 4) to boost production
Surprise !!
totally suppressed the "cell-mediated response“ which combats viral infection
Mousepox 100% lethal
2001
December 19, 2007
Boy gets leukaemia after gene treatment to cure ‘bubble baby syndrome’
3 year-old with X-linked severe combined immunodeficiency (X-SCID) - immune system fails to develop
Treated with genetically modified virus to correct the faulty DNA that causes X-SCID
Inserting the replacement DNA activated another gene that promotes cancer
Now an acknowledged risk of gene therapy
Also seen in 4 / 11 patients in a French trial One has died while 3 are in remission
Retrovirus vector
Regulations governing the handling of gene therapy vectors
No additional regulations governing the handling of Non-Infectious vectors
Non-viral & Non-bacterial
Viral vectors are Genetically Modified
Genetically Modified Organisms (GMOs)
Genetic Modification
Genetic modification is officially defined as ‘the alteration of genetic material (DNA or RNA) of an organism by means that could not occur naturally through mating and/or recombination’
A guide to Genetically modified organisms (Contained Use) Regulations 2000. Health and Safety Executive
Regulations governing the handling of gene therapy viral vectors
Two sets of Regulations:
GMO (Contained Use) Regs 2000, 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
aimed at laboratories (difficult to interpret clinically)
no reference to product or patient safety
Additional Regulations that apply to Gene Therapy Clinical Trials
Protection of the Patient
Gene Therapy Advisory Committee (GTAC)
Established 1993, Department of Health
UK national research ethics committee (REC) for gene therapy
Ethical acceptability for human gene therapy
Scientific merits
Potential benefits and risks
Patient flagging and long term monitoring
Advice to UK health Ministers on developments in gene therapy research
Applies to ALL GENE THERAPY CLINICAL TRIALS using viral and non-viral vectors
Containment Levels for GMOs Containment Measures Required Isolatable Lab Suite Microbiological Safety Cabinet Gloves Protective Clothing Class 1 Level 1 NO NO NO YES Requires first use of premises notification to HSE Class 2 Level 2 NO Risk Assessment R/A R/A YES Minimum requirement for any human blood or clinical samples. Requires HSE notification Class 3 Level 3 YES YES YES YES + Footwear Requires HSE notification Class 4 Level 4 YES YES YES YES Complete change of clothing and footwear on entry and exit Requires HSE notification
Guidelines on Handling GMOs in Pharmacy
QA of Aseptic Preparation Services (4th Ed n. ) Appendix 6 Gene Therapy
Scientific Advisory Committee on Genetic Modification (SACGM), Part 6, Guidance on the use of genetically modified micro-organisms in a clinical setting
European Association of Hospital Pharmacists (EAHP) Guidance on the Pharmacy Handling of Gene Medicines
Rules and Guidance for Pharmaceutical Manufacturers and Distributors 2007 – No Specific Guidance
APPENDIX 6 - GENE THERAPY
Facilities
Documentation
Labelling
Training
Aseptic processing
Cleaning
Storage
Transport
Waste Disposal
Spillage
Facilities
Gene therapy should not be manipulated in clinical areas
Gene therapy trials worldwide. Provided by the Journal of gene medicine http://82.182.180.141/trials/index.html
A guide to Genetically modified organisms (Contained Use) regulations 2000. Health and Safety Executive
Genetically Modified Organism (Deliberate Release) Regulations 2002 [GMO(DR)]. Department for the Environment, Food and Rural Affairs (DEFRA) http://www.opsi.gov.uk/si/si2002/uksi_20022443_en.pdf
EU Clinical Trials Directive. http://www. wctn .org. uk /downloads/EU_Directive/Directive. pdf
Implications of gene therapy for hospital pharmacists. Simpson.J, Stoner. N. www.pjonline.com/pdf/articles/ pj_20030726_ genetherapy .pdf
Additional Information
Cancer gene therapy: from science to clinical trials . Searle. P.F, Spiers. I, Simpson. J, James. J.D. Drug Delivery Systems and Sciences 2002, 2 (1), 5-13.
Standards for gene therapy clinical trials based on pro-active risk assessment in a London NHS Teaching Hospital Trust. Bamford, K.B., Wood, S., Shaw, R.J. QJM 2005, 98, 75-86. www. qjmed . oupjournals .org
Progress in Gene Therapy – are hospital pharmacies the next barrier? Simpson, J. Hospital Pharmacist , 2006 , 13 (8), 266 http://www. pjonline .com/ pdf /hp/200609/hp_200609_comment. pdf
Cancer Biotherapy. An Introductory guide. Young, A. Rowett, L. Kerr, D. Oxford University Press 2006
Scientific Advisory Committee on Genetic Modification (SACGM), Part 6, Guidance on the use of genetically modified microorganisms in a clinical setting. http://www. hse . gov . uk / biosafety / gmo / acgm / acgmcomp /part6. pdf
European Association of Hospital Pharmacists (EAHP) Guidance on the Pharmacy Handling of Gene Medicines. http://www. ejhp . eu /
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