Download - Gene Therapy
Gene Therapy - Problems and Challenges
Alison M. Beaney
Regional Quality Assurance Specialist
North-East and Yorkshire
Helapet Aseptic Study Day 2008
2
Gene Therapy
• Background to Gene Therapy• Potential Benefits• Perceived Hazards and Risks• Regulations• Implications for Pharmacy Aseptic Units• Future?
3
Gene Therapy• Definition
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 4
5
Gene Therapy Vectors
• Vectors deliver genes to cells
Therapeutic gene (Transgene)
Therapeutic proteinVector for efficient gene delivery
Transcription
Translation
6
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
7
Gene Therapy Strategies
1) 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
2) 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
8
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
10
Regulations governing the handling of gene therapy vectors
• No additional regulations governing the handling of Non-Infectious vectorsNon-viral & Non-bacterial
• Viral vectors are Genetically Modified• Genetically Modified Organisms
(GMOs)
11
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
12
Regulations governing the handling of gene therapy viral vectorsTwo 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
13
Additional Regulations that apply to Gene Therapy Clinical Trials
Protection of the PatientGene Therapy Advisory Committee (GTAC)
Established 1993, Department of HealthUK 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 monitoringAdvice to UK health Ministers on developments in
gene therapy researchApplies to ALL GENE THERAPY CLINICAL
TRIALS using viral and non-viral vectors
Containment Measures RequiredIsolatabl
e Lab Suite
Microbiological Safety Cabinet
Gloves Protective Clothing
Class 1Level 1
NO NO NO YES Requires first use of premises notification to HSE
Class 2 Level 2
NO Risk Assessme
ntR/A
R/A YES Minimum requirement for any human blood or clinical samples.Requires HSE notification
Class 3Level 3
YES YES YES YES+ Footwear
Requires HSE notification
Class 4Level 4
YES YES YES YESComplete change of
clothing and footwear on entry and
exit
Requires HSE notification
Containment Levels for GMOs
15
Guidelines on Handling GMOs in Pharmacy
• QA of Aseptic Preparation Services (4th Edn.) 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
16
17
FacilitiesGene therapy should not be manipulated in
clinical areas
Basic Principles - Containment - Knowledge / understanding /
skill - Validated procedures Persons handling the product should be masked and gloved All disposable equipment and materials used for prep & admin -
handled as biohazardous
• Dedicated facilities required -ve pressure isolators or Class II BSC+ve pressure room or lobbyContainment level > 2
Clean room suite designed to provide protection to the cleanroom
19
Aseptic ManipulationDoses
Calculation / dilutions / multiple dilutionsNeedle stick injury riskUnits
Particle Units/ml (PU/ml)Plaque Forming Units/ml (PFU/ml)Infectious particle Units/ml (IU/ml)Gene Transfer Units/ml (GTU/ml)
StabilityContainer compatibilities - Plastic/glass
adhesionExpiry date - Time to administration from thawing
20
Decontamination• Cleaning
Virucidal detergents (validated against GT vectors)
Cleaning ValidationSpecific Detection methods needed for viruses
that are virus specific and highly sensitive
• Waste DisposalOn site validated autoclave for re-usable
equipment Inactivation on-site for Class 3 vectors
Validated autoclave Incineration Disinfectant treatment
21
• SpillageSpecific to GT vector Spillage kit
Contents ( gloves, masks, aprons, goggles, disposable shoe covers, virucidal detergents, absorbent material, disposable forceps & biohazard incineration bag)
Positioned in all GT handling areasNotification to HSE
Accidental Exposure
22
SOPs neededSafe handling & protectionStorageOperators
(Not pregnant, breastfeeding or immunosuppressed)Training FacilitiesSpillage, contamination & needle stickWaste disposal, cleaning and transport
23
Risk Assessment
• Assess each product individuallyCytolytic virusesNon-cytolytic virusesReplication competentReplication deficientClass I, II or III
24
What will the Future bring?Dedicated facilitiesAutomation?The first gene medicine in Europe could be
licensed in 2008Licensed closed-system gene therapy productsUse of gene therapy as an adjunct to standard
therapy e.g. Radiotherapy & ChemotherapyVector development e.g.
Targeted vectors (viral & non-viral)Bacterial vectors
25
Additional Information Gene Therapy Advisory Committee (GTAC)
http://www.advisorybodies.doh.gov.uk/genetics/gtac/index.htm 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
Quality Assurance of Aseptic Preparation Services Fourth Edition. A.M. Beaney. Pharmaceutical Press 2006. Appendix 6. Gene Therapy.
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
26
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/