The development of ASO Drugs Flashcards
What are ASO’s
Short single stranded DNA or RNA sequences
Anneal to gene by Watson-Crick base pairing
Oligonucleotides are chemically modified
What are the chemical modifications of ASO’s
- increases stability (resistance to endogenous nucleases)
- increases half life
- increases binding affinity
- increases specificity
- reduce toxicity
Action mechanisms of ASO
Gene silencing
- generic silencing
- Allele-specific silencing
Splice switching
- Exon skipping
- Exon inclusion
Targeted gene upregulation
- poison exon skipping
- blockage of translation inhibitory elements
- blockage of naturally occurring antisense transcripts
Spinal muscular atrophy
2nd most common autosomal recessive disease
1 in 6000-10,000 live births; carrier: 1 in 35~ 50
Degeneration of alpha - motor neurons in the spinal cord and lower brainstem
SMA ASO THERAPY
Nusinersen: 18-mer MOE
Intron 7 (ASO 10-27)
A single injection of PMO25 prolonged the lifespan by over 200 days
Nusinersen (spinraza) treatment in SMA
FDA approval - 2016
EMA approval - 2017
NICE - 2019
Regular intrathecal injection - 12mg
Loading: 1-60 days
Maintenance : day 60 - …
^ once every four months for life
$ 125,000 an injection
1st year $775,000
After: $375,000
> 29,000 patients treated
Challenges
Delivery:
Upon systemic administration:
- up to 18-40% ASOs accumulate in the
kidneys.
- up to 40-50% ASOs accumulate in the liver
- blood brain barrier
I targeted oligos end up in
- Kupffer cell
- Endothelial cell
Kidney, liver > bone marrow > spleen»_space;>
Strategies to enhance delivery
- Bio-conjugation
- Organ- or cell-targeted deliveries are more
preferable
1. Peptide-conjugated ASO therapy (targeting the transferring receptor to transport anti-sense oligonucleotides across the mammalian blood-brain barrier
GaINAc-AON: Hepatocyte Specific Delivery
- N-acetylgalactosamine (DaINAc) —> ligand
to the asialoglycoprotein receptor (ASPGR) - ASPGR expression: hepatocytes (95%),
kidneys (5%) - ASPGR is highly expressed on hepatocytes
(500,000 copies/cell) - A single receptor can cycle up to 200 times
with a turnover time of around 15 minutes - Increases in vivo efficacy by 10-20 fold in
rodents and 30 fold in the clinics - Givlaari - worlds first ever approved GaINCa-conjugated RNAi targets ALAS1 for the treatment of acute hepatic porphyria (FDA-Nov 2019)
Transthyretin (TTR) Amyloidosis
Global prevalence (1 in 50,000 - 100,000)
Caused by dominant mutations in the TTR gene
- TTR mRNA
- TTR tetramer
- folded dimers
- folded monomers
- misfolded amyloidogenic monomers
- small oligomers/ amorphous aggregates
- amyloid fibrils
RNA therapy for hereditary transthyretin (TTR) amyloidosis
Inotersen - ASO
- no formulation
- subcutaneous
- 300mg weekly
^ Eplontersen - GaINAc - ASO
45mg monthly, SC
————————————————————
Patisiran - siRNA
- LNP formulation
- intravenous
- 0.3mg/kg, every three weeks
^ Vutrisian - GaINAc - siRNA
25mg every 3 months, SC
Trial- inability
Milasen
patient customised oligonucleotide therapy for a rare genetic disease
Case:
- 6yr old with onset of blindness, ataxia,
seizures, developmental regression
- at 7, the condition continued to
deteriorate
- inability to make discernible words,
dysphasia, need for substantial support to
walk, 15-30 seizures a day
- diagnosed with CLN7/MFSD8 Batten
disease (Abnormal splicing and translation
after SVA insertion)
- no treatment currently available
A roadmap of nucleic acid therapies for rare diseases
Genetic diagnosis
Genetic analysis & NAT design
Preclinical Development & Manufacturing
Regulatory approval & clinical trials
NAT drug for RD patients
