Correction approaches for DMD May 28 2014
Some basic biology: genes & proteins • Proteins are building blocks of our body • Genes contain blueprint for proteins
Annemieke Aartsma-Rus
Gene Protein Cel nucleus DNA
Temporary gene copy(RNA) Cell body (cytoplasm)
Protein factory
Annemieke Aartsma-Rus
Some basic biology: genes & proteins • Proteins are building blocks of our body • Genes contain blueprint for proteins Mistake in gene
Mistake in RNA transcript
Mistake in Protein Annemieke Aartsma-Rus
Dystrophin
Dystrophin
Annemieke Aartsma-Rus
Duchenne: no functional dystrophin
Annemieke Aartsma-Rus
No functional dystrophin Muscle damage
Repair
Inflammation
Less blood flow
Too much Ca2+
Oxidative stress
Energy production impaired
Fibrosis
Loss of muscle tissue Loss of muscle function Annemieke Aartsma-Rus
Correction approaches Mistake in gene
Mistake in RNA transcript
Correct for mistake in Protein Annemieke Aartsma-Rus
Utrophin upregulation Nerve
Muscle
Dystrophin
Annemieke Aartsma-Rus
Utrophin
Utrophin upregulation • Utrophin resembles dystrophin • Utrophin can partly take over dystrophin function • Expressed in nerve cells, hardly in muscle • Find ways to get more utrophin in muscle
Annemieke Aartsma-Rus
Utrophin upregulation • Find compound to switch on utrophin gene volume • High throughput screening in cell models • Potential drugs screened further in patient-derived cell cultures and mouse models • Candidate drug tested in healthy volunteers (BMN195/SMNT C1100) by Biomarine • Uptake not sufficient Annemieke Aartsma-Rus
Utrophin upregulation • Summit made new formulation • Tested in healthy volunteers • Uptake much improved • Levels in blood now sufficient to increase utrophin • Tests in DMD patients being prepared • Safety dose finding trial complete • Phase 2 trial (2014) Annemieke Aartsma-Rus
Utrophin upregulation PTC • Finding compounds to improve translation from gene to protein Tivorsan • Biglycan protein delivery • Recruits utrophin and other dystrophin associated proteins
Annemieke Aartsma-Rus
Utrophin vs. Dystrophin • Similar proteins, but not identical • Utrophin can take over many dystrophin functions • Utrophin does not recruit nNOS (important to have sufficient blood flow to contracting muslce) • Utrophin does not recruit energy producing organels (mitochondria)
• Approach applies to ALL Duchenne patients (mutation independent) Annemieke Aartsma-Rus
Correction approaches Mistake in gene
Correct for mistake in RNA transcript
Correct for mistake in Protein Annemieke Aartsma-Rus
Exon skipping
Annemieke Aartsma-Rus
Duchenne: genetic code disrupted
Annemieke Aartsma-Rus
Duchenne: genetic code disrupted Exon 46
Exon 47
?
Exon 51
Exon 52
Protein translation stops prematurely
Dystrophin not functional Annemieke Aartsma-Rus
Becker: genetic code maintained
Annemieke Aartsma-Rus
Becker: genetic code maintained Exon 46
Exon 47
Exon 52
Exon 53
Protein translation continues
Dystrophin partly functional Less damage Annemieke Aartsma-Rus
Exon skipping: restore genetic code
Annemieke Aartsma-Rus
Exon skip chemistries • Two chemistries in clinical development • GSK/Prosensa: 2’-O-methyl phosphorothioate (drisapirsen) • AVI-Biopharma/Sarepta: phosphorodiamidate morpholino oligomers (eteplirsen) • Exon 51
Annemieke Aartsma-Rus
Systemic study Sarepta II AVI-4658 (30 and 50 mg/kg) • Intravenous delivery • Earlier trial:20 mg/kg (12 weeks) is not sufficient • Weekly 12 weeks 50 mg/kg: biopsy • Weekly 24 weeks 30 mg/kg: biopsy • Weekly placebo 12 or 24 weeks: biopsy • After 24 weeks treatment: all 30 or 50 mg/kg/week • Patients have been treated for >90 weeks now Annemieke Aartsma-Rus
Dystrophin staining
Annemieke AartsmaRus
Department of Human Genetics
Annemieke Aartsma-Rus
24
Dystrophin results
Annemieke AartsmaRus
Department of Human Genetics
Annemieke Aartsma-Rus
25
Eteplirsen summary • Dystrophin restored for all patients 24 weeks after treatment • 6 minute walk test stabilized in 10/12 treated patients • No real placebo group • Sarepta plans confirmatory study for 2014 • Also preclinical work ongoing for exon 50, 45, 53 and 44) Annemieke Aartsma-Rus
Systemic trial (GSK/Prosensa) • Following dose finding study, all patients enrolled in an open label extension study • 6 mg/kg drisapirsen per week for 72 weeks • Then 8 weeks break • Then cycles of 8 weekly doses, 4 week break • All patients still in trial • Treated now for almost 4 years
Annemieke Aartsma-Rus
Goemans et al, NEJM 2011, 364: 1513-22
Open Label Extension Trial Drisapersen • Side effects observed • Local injection site reactions • Proteinuria (reversible during breaks) • Thrombocytopenia seen for some patients • Seen in all phase 2/3 trials drisapersen • 6 minute walk distance maintained for >3.5 years in 8/10 ambulant patients • Very encouraging results but no placebo group Annemieke Aartsma-Rus
Primary Endpoint: Change from Baseline (95% CI) in 6MWD (m), ITT Population
Visit
Comparison
Week 25 (Primary)
Week 49 (Secondary)
Treatment Difference
P-value
Weekly vs Placebo
35.09
0.014
Intermittent vs Placebo
3.51
0.801
Weekly vs Placebo
35.84
0.051
Intermittent vs Placebo
27.08
0.147
Study Design large placebo controlled trial
n = planned number randomized Numbers randomized (ITT and safety population) 6 mg/kg/week = 125 Placebo = 61
Primary Endpoint: 6MWD Adjusted Mean Change from Baseline (95% CI) in 6MWD (m) – Primary MMRM analysis ITT Population
Treatment difference = 10.3m, p-value = 0.415 at Week 48
- 42.3 m 4.7m
4.8m
1.8m
- 52.7 m Curves offset for visualization
Drisapersen most recent news • GSK stops drisapersen development • Prosensa obtained all rights and data
• Further analysis done • Phase 3 population more advanced disease • For many patients 96 week information available Annemieke Aartsma-Rus
Drisapersen preliminary further analysis
Annemieke Aartsma-Rus
Drisapersen preliminary further analysis
Annemieke Aartsma-Rus
Other trials Prosensa/GSK Drisapersen •Redosing patients anticipated to start Q3 2014 •Discussion with regulators ongoing
Exon 44: •Study completed, extension anticipated Q3/4 2014
Exon 45 and Exon 53: •Dose finding studies ongoing •Anticipate 2nd phase 2015
Preclinical work: •Exon 55 & exon 52 and rare mutations Annemieke Aartsma-Rus
Stop codon readthrough
1
79
Annemieke Aartsma-Rus
PTC124/ataluren PTC
1
79 Cell ignores new stop signal Complete protein is made
Annemieke Aartsma-Rus
PTC124/Ataluren • Tested in healthy controls: safe • Tested in 28 patients (dose finding) • Safe • Increased dystrophin expression
• Tested in 174 patients in 48 week trial • Placebo, high dose and low dose • Safe! • No significant difference in primary outcome (6MWT) • Dystrophin levels? (analysis pending) Annemieke Aartsma-Rus
PTC124/Ataluren • Tested in healthy controls: safe • Tested in 28 patients (dose finding) • Safe • Increased dystrophin expression
• Tested in 174 patients in 48 week trial • Placebo, high dose and low dose • Safe! • No significant different in primary outcome (6MWT) • Dystrophin levels? (analysis pending) Annemieke Aartsma-Rus
PTC124/Ataluren dosing • Dosing not optimal • Research done • Optimized dosing
effect
• Bell shaped curve
concentration
• May be responders and non-responders • Extension studies re-initiated in USA and Europe • New placebo-controlled trial started in USA and Europe in 220 patients • Requested conditional approval with EMA Annemieke Aartsma-Rus
Stop codon readthrough summary
Annemieke Aartsma-Rus
Correction approaches Correct for mistake in gene
Correct for mistake in RNA transcript
Correct for mistake in Protein Annemieke Aartsma-Rus
DNA editing • DNA has a repair system • Activated upon DNA damage • Use this system to correct for DNA mistakes? Mutation Template with correct DNA information
DNA repair system Mistake corrected (in one cell) Annemieke Aartsma-Rus
DNA editing • Challenge: DNA repair system very inefficient (1 in 1,000,000 – 1,000,000,000 cells)
• Much more efficient when DNA is ‘broken’ (1 in 10-1000 cells)
Have to generate DNA breaks at/close to mutation
Annemieke Aartsma-Rus
DNA scissor system • DNA scissors can cut DNA at specific location
Scissor cuts at/near mutation
Repair break with template (Correct small mutations)
Annemieke Aartsma-Rus
Repair break without template Small mutations will be introduced (can correct genetic code like exon skipping)
DNA scissor system • DNA scissors can make breaks in DNA • Different types of scissors in development • Zinc Fingers, TALENs and RGNs • Challenge: deliver scissors and templates to muscles
Annemieke Aartsma-Rus
49 | TREAT-NMD Outcome Patient Care Joint EuroBioBank Standards Action & Website 2007-2011 Registries measures Trial research TACT SOPs Plan Site of & EU fundedRegistry Network Diagnosis Communication & Care
Three year work plan
www.treat-nmd.eu
Standardized genetic & Unique network of 18 Tests to decide whether TREAT-NMD Unified Regular experimental meetings 3 year Advisory plan to clinical2012 core data for trial members treatment being tested in onwards consolidate protocols Committee improve efforts and the for International consensus Information Extensive about website each recruitment a comparability trial is Alliance having any effect funded jointly Milestone-driven tackle Therapeutics, ofcommon studies publication recommended registered trial site kept in Stores & distributes problems approach through multiple 250,000 annualfor page hits standards of care Interface can vary one location ease of 440,000 Vital to quality use the DNA, correct cell Drawn Expert multidisciplinary up by a group of streams with global between countries whilst comparison outcome and tissue measure samples to 70,000 visitors annually Topics independent Maintains on researchers necessity, network body DMD-SMA-CMD-LGMD stillbased able to share core partners & membership prove if a in treatment works (listed momentum hosting each to & be protocol) establish rotated data Addresses organisational Monthly newsletter sent Independent between and new objective partners goals Family guides difficulties of identifying Governance Working harmonise the toto 3,500 recipients Ethical & governance best Approx guidance 40 sops on advancing updated in 25 different languages appropriate sites when Chair –of Annemieke Aartsmause most appropriate practice new therapies regularly for translations verified Rus setting up a trial Proven communication outcome measures for neuromuscular diseases Vice Chair – Ericplatform Hoffman >10,000 DMD diseases patients different Printed booklets or across countries Leads --30 Eric Hoffman Executive Committee Leads Marina Mora download from Lead Eugenio Mercuri Annemieke Aartsma-Rus Supported by academic Lucia Monaco Chair- Jan – Dominic Wells Secretariat - Verschuuren Katewebsite Bushby Leads Filippo Buccella
advisory boardVolker (“task force”) Marco Crimi Straub Coordinated Hugh by University Dawkins Funding - Telethon & Parent of NMD leaders Funding - US Sejersen (Dept of Leads - Thomas Medical Center Freiburg Organizations Funding COST Funding -Kathy Fondazione Funding – EC Defense) Funding -(operating AFM North & EC Telethon grant) (operating grant)
Summary • Some therapeutic approaches are mutation specific: good diagnostics crucial • Much is known about Duchenne – mainly through research funded by patient organisations • No treatment available yet • Improved care has had huge impact on disease progression and quality of life
Annemieke Aartsma-Rus