Gene Therapy - Problems and Challenges

Alison M. Beaney

Regional Quality Assurance Specialist

North-East and Yorkshire

Helapet Aseptic Study Day 2008

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Gene Therapy

• Background to Gene Therapy• Potential Benefits• Perceived Hazards and Risks• Regulations• Implications for Pharmacy Aseptic Units• Future?

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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

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Gene Therapy Vectors

• Vectors deliver genes to cells

Therapeutic gene (Transgene)

Therapeutic proteinVector for efficient gene delivery

Transcription

Translation

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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

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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

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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

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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)

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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

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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

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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

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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

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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

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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

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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

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• 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

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SOPs neededSafe handling & protectionStorageOperators

(Not pregnant, breastfeeding or immunosuppressed)Training FacilitiesSpillage, contamination & needle stickWaste disposal, cleaning and transport

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Risk Assessment

• Assess each product individuallyCytolytic virusesNon-cytolytic virusesReplication competentReplication deficientClass I, II or III

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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

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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

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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/