Emerging treatments Flashcards
What pathways with metabolism are usually affected with genetic disease?
- Usually alternate product
- Carbohydrate
- Fatty acid
- Proteins
- lack enzyme
What are some examples of inborn errors of metabolism disease?
PKU
MCAD Deficiency
Maple Syrup Urine Disease
Homocystinuria
What is PKU caused by? What does this cause?
1 Caused by lack of phhenylanine hydroxylase (so not transformed into tyrosine)
- So increased levels of phenylanine which turns into phenylketones
- Both of these are neurotoxins
What does untreated PKU lead to?
-Major cognitive impairment behavioural difficulties fairer skin, hair and eyes than siblings -lack of melanin -recurrent vomiting
How is PKU treated?
Treated with low protein diet – Tyrosine supp
Before treatment need to identify cause
Possible before gene identified - biochemistry
-Lack of PAH 1960’s PKU screening introduced (just measuring levels can’t see gene as not known)
-1984 PAH mutation identified
What is Haemophilia?
- Blood clotting disorder
- Known since ancient times
- Uncontrolled bleeding
- Bleeding into joints
- excruciating pain
- Bleeding into brain
- Internal bleeding
- Untreated fatal
How do you treat haemophilia?
1968 - First FVIII concentrate available 1970s - Freeze-dried plasma-derived factor concentrates available However Not all good news 1970-1980s 5000-30000 given clotting factors contaminated with HIV and hepatitis 2500 so far died 1980s - heat treat products kill virus 1980s - Factor VIII gene cloned 1990s – Recombinant Factor VII treatment So now pure and disease free
How is Growth hormone deficiency treated?
Injection growth hormone now recombinant (cadaver derived cjd)
How is lysosomal storage diseases treated?
-This affects lysosomal breakdown
How is Fabry disease treated?
•Injection recombinant alpha galactosidase A
How is Pompe disease treated?
•Injection of alpha glucosidase
How are drugs approved?
- Discovery
- Animals
- 3 clinical phase
- Approval EMA FDA
- For NHS, NICE and look at evidence, cost and value for money
What are some therapies targeting proteins?
- These are treatments not cures
- Try to normalise function of mutant protein
Why are pharmalogical chaperons used?
- Protein folding is complex sometime fails
- System in ER degrades misfolded proteins
- Some mutations prevent proteins folding properly
- Subject degradation pathway
If folded correctly would be active
What is Fabry disease?
deficiency α-galactosidase A
What is a result of Fabry disease?
Build up of globotriaosylceramide
What is a pharmacological chaperon for Fabry disease?
-Some mutations cause misfolding
-Migalastat small molecule chaperone
Stabilises enzyme in correct shape
NICE approved Feb 2017
-Mutation specific (have to same mutation)
What are pharmacological modulators?
Commonly used drugs:
1. Receptor agonists/antagonist
2. Ion channel activators/blockers
-Can design one that has these effects on mutant receptor or channel
- e.g. Bcl-abl Kinase inhibitors (Philadelphia chromosome)
What is cystic fibrosis?
- Defective chloride channel
- Mutations (33) cause channel not to open
What is a treatment for cystic fibrosis?
- Design a drug which causes activation - Ivacaftor binds tochannel and make it more open
- Is mutation specific (treatment won’t work without this mutation)
How is cystic fibrosis caused treated with combination therapy?
- Defective chloride channel
- One mutation (f508del) misfolded, inactive channel
- Treat with combination chaperone and activator
- Orkambi (Ivacaftor/lumacaftor) – -NICE approved Oct ’19
- Not cure does improve lung function
What is a stop Condon read through?
Some diseases caused by non-sense mutation
-premature stop codon
-This prevents protein production
Can drugs be used to prevent this
What is amino glycoside antibiotic?
-Aminoglycoside antibiotics bind to ribosome
-Causemistranslation
Drugs based on these → read through non-sense mutations
How is stop codon read through used in DMD and BMD?
Duchenne muscular dystrophy – premature stop
-Becker muscular dystrophy – missing section
-If read through premature stop DMD → BMD
-Ataluren – approved in EU not in US
NICE approved – June 2016
-Non-sense mutation specific
Why is gene therapy hard?
-Achieving specificity
-Getting therapy to right place
-maintain expression
Why is gene therapy easy in theory?
- Recessive disease - replace defective gene
2, Dominant disease – delete defective gene
When is it easier to do gene therapy?
Much easier to achieve in vitro than in vivo
What does in vivo mean?
In the living
What doe ex vivo mean?
out of the living
What does in Vitro mean?
In glass
How do you undertake mitochondrially inherited disease therapy?
- Only effective therapy
- Requires IVF
- Take DNA from fertilised patient egg
- Transfer to donor egg normal mitochondria
What are the two ways to do mitochondrial inherited disease therapy?
- Maternal spindle transfer
2. Pro-nuclear transfer
What is maternal spindle transfer?
- Chromosomes are removed from an unfertilised egg that has mutated mitochondrial DNA
- These are added to an unfertilised donor egg that has had its nucleus removed
- This fused egg is fertilised in vitro
- The egg develops normally to from an embryo
What is pronuclear transfer?
- An egg with mutated mitochondria DNA is fertilised in vitro
- The resulting pro-nucleus is removed
- This is transferred to a fertilised donor egg that has had its pronucleus removed
- The fused egg develops normally
What are the views in mitochondrial inherited disease therapy?
Approved for use in UK Not without controversy Popularly know as three-parent babies Mitochondrial DNA 16 569bp Genome 3 088 269 832bp
What is virus gene therapy?
Can engineer virus to carry therapeutic gene
What are examples of viruses used?
AAV
Adenovirus
Lentivirus – HIV
Vaccinia
What does the virus choice depends on?
- Virus choice depends on target tissue
- Amount of DNA limited depends on virus
What is the Chimeric Antigen Receptor T cell used? (CAR-T)
-To treat cancer
-T-cell receptorantigen bound to MHC
-Low affinity
-CAR – recognise antigen directly + higher affinity
-Variable region monoclonal antibody scFv
-recognise cancer cell
-T cell receptor and co-receptor signalling domain
What is the process of CAR T cell therapy?
1, Isolate patients T-cells
- T-Cells expanded
- Transfected with CAR – lentivirus
- CAR-T cells expanded
- Reinfused into patient (suppress patients T cells)
- Currently approved for some B-cell lymphomas
When do you use CAR T cell therapy?
- If other therapies haven’t worked
- Can cause cytokine release syndrome, neurological damage.
- Being investigated for solid tumours
How is in vivo gene therapy supplement used?
Useful lack of a functional gene
How do you carry out in vivo gene therapy?
-Use a virus to carry in working copy
1. Can inject systemically
2. Can inject locally
-Eye
-Spine
-Brain
Many treatments in development
What is Leber congenital amaurosis type 2?
- Recessive disease caused by mutation RPE65
2. Progressive blindness – loss of retinal cells
How is Leber congenital amaurosis type 2 treated?
- Luxturna rAAV2 expressing RPE65
- Not cure – greatly improves vision
- Patients need sufficient remaining cells
- EMA approved Nov 2018
- NICE approved Sept 2019
What are Anti-sense oligonucleotides?
- Antisense oligonucleotides
- Short modified nucleic acid complementary to target
How do Anti-sense oligonucleotides work?
- Modification prevents degradation allow entry to cell
- Binds to target
- Block translation
- Can also alter splicing
- Relatively cheap to make
What is in vivo therapy knockdown?
- Useful for diseases caused by gain of function
- Currently no successful therapies
- Number in late stages of clinical trials
- Ones closest to use oligonucleotides
- RG6042 Huntington’s disease phase III trial
- Mutation specific
What is exon skipping?
- During pre-RNA processing
- Oligonucleotides cause exon to be skipped
- Can be used to skip disease causing exon
- To put RNA back in reading-frame
- Useful in limited circumstances
6.Exons skipped mustn’t be vital
Generally only large proteins
