Post on 01-Jun-2022
Gene Therapy and Gene Editing
Topics
• Background in technology• Where are we to date?• What applications• What ‘issues’
Rob Hoeben
Molecular Cell Biology; LUMC
Impact of genetics
How to modify a cell with a faulty gene?
• Very efficient• Very stable• Safety concerns
- Patient- Environment
Result of random gene therapy
Severe Combined Immune Deficiency
~80 SCID variants:
• X-linked SCID
• ADA-SCID
• Rag1 en Rag2
• Wiskott-Aldrich syndrome
• Chronic granulomatous syndrome
• Artemis
• XLA
SCID gene therapy
• ~ 75 children with SCID treated
• 94% alive and thrivingN.B. non-matched BM transplantation: 60% success rate
• But SAEs16 patients developed leukemia
5 / 19 SCID gamma-c receptor7 / 9 WAS WAS-protein4 / 4 CGD NADPH oxidase0 / 40 ADA adenosine deaminase
Vector improvement
Fisher et al., Clin.Genet. (2015) 88:507-15
repair
The Next Frontier: Therapeutic Genome Editing?
The Next Frontier: Therapeutic Genome Editing?
Efficient gene knock-out with targeted nucleases
Double-stranded breaks are detrimental and need repair
Efficient knock-out with nuclease vectors: Cas9/CRISPR
NHEJ
Some numbers
Targeted indel formation: up to 70 %Off-target indels: ?
targeted integrations: up to 2 – 10%Off-target integrations: < 2 % of total integrations
Reducing the occurrence of off-target indels
• Pairs of nicking nucleases
• Reduce the affinity of Cas9 for DNA
Gene Editing is Feasible
Somatic-Cell Gene-Editing Therapy: Targets I
Low hanging fruits:
(1) Recessive disorders where ‘indels’ could be ‘therapeutic’
• Thalassemia• Hemophilia• Pompe disease• (Duchenne muscular dystrophy)
(2) Infectious disease• AIDS - CCR5 deletion
(3) Cancer• CAR –T cells - endogenous TCR deletion
Mut 1Mut 2
Somatic-Cell Gene-Editing Therapy: Targets II
(4) Dominant disorders where ‘indels’ could be ‘therapeutic’• Huntington’s disease
(5) Recessive disorders requiring gene replacement or correctionMost recessive disorders• Hemophilia • SCID
NB Indels 2-component systemReplacement 3-component system
Somatic-Cell Gene-Editing Therapy: Requirements
• Basic technology• Preclinical models• Proof of principle• Vector production
• viral vectors• protein transduction
Prospect of ‘Personalized treatment’
Somatic-Cell Gene-Editing Therapy: Requirements
Evolution of the fieldVaccinesOncolytic virusesDefective viral gene vectors (classic gene therapy)Targeted‐nuclease vectors (therapeutic indels)Targeted‐nuclease vectors for gene replacement
Key issues: 1) Limited Expertise in Translation to Clinic2) Limited Capacity in GMP Vector Production3) Uncertainty on Safety /Quality Control Requirements4) Uncertainty on Financial Paradigm