Daniel J. Abrams, MD December 2012
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CNS Drug Delivery: Beyond the Spinal Cord
Mission: Improve outcomes for epileptic patients who don’t respond to conventional treatments by administering reformulated, micro-doses of anti-epileptic drugs directly to the brain.
Daniel J. Abrams, MD December 2012
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• This presentation includes the description of drugs, devices and their therapeutic uses that are in early stages of development, are not commercially available and have not been approved by regulatory institutions.
• Before commercialization is possible the drugs, devices and their therapeutic uses need to undergo additional preclinical and clinical evaluation and obtain regulatory approval.
Disclaimer on Product Use
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Significant Unmet Medical Need for Neurological Disorders and Disease
• Large # of Indications
• Growing patient
populations
• Few effective therapies
Enormous cost of care
Parkinson's Disease
Glioma
Neurometabolic Syndrome
Spinal Muscular Atrophy
Cerebral Palsy
ALSHuntington's Disease
Alzheimer'sDisease
Traumatic Brain Injury Stroke
Epilepsy
Chronic Pain
Spinal Cord Injury
Multiple Sclerosis
~15M US Patients
Epilepsy
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U.S. Epilepsy Market
Total Patients 1.0% or 3 million1
Refractory Patients 1,000,0002
Most Severe Refractory Patients 600,000
Refractory Epilepsy Treatment Market $2.5 billion
Antiepileptic Drug Market (World, 2008) $11.34 billion
Implantable Pump Market- Pain & spasticity applications
10,000 units,$600 million
1http://www.epilepsyfoundation.org/aboutepilepsy/whatisepilepsy/statistics.cfm2http://www.touchneurology.com/articles/update-and-overview-international-league-against-epilepsy-consensus-definition-drug-resista
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The Blood Brain Barrier excludes most drugs from Brain and Spinal Cord . . .
. . . despite most dense vascular bed of any organ.
*radioactively labeled tracer drug given intravenously
Gabapentin, smallmolecule (0.2kD)
Prialt, peptide(3kD)
siRNA(13kD)
protein – antibody(150kD)
Drugs keep getting bigger:
Factors Frustrating CNS Drug Therapy
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Peripheral Capillary Brain Capillary
permeability restricted to:• small molecules (<600D)• lipophilic substances
Protein
Glucose
Selectivity of the Blood Brain Barrier
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Blood Brain BarrierBlood Brain Barrier
apposed endothelium(no fenestrations - holes)
tight junctions
glial endfeet
Physical Barriers
Functional Barrierslimited vesicular uptakemulti-drug resistance (MDR) gene
Blood Brain BarrierBlood Brain Barrier
apposed endothelium(no fenestrations - holes)
tight junctions
glial endfeet
Physical Barriers
Functional Barrierslimited vesicular uptakemulti-drug resistance (MDR) gene
Anatomy of the Blood Brain Barrier
Electron Micrograph ofTight Junctions
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Crossing the Blood Brain Barrier
1. betweenpermeabilize tight junctions
3. arounddirect intracranial drug delivery
2. throughenhance transport acrossthe endothelium
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1980
1982
1988
1990
1991
1992
1996
2000
2004
2010
2012
First human implant of SynchroMed pump (Medtronic)SynchroMed pump receives FDA approval (Medtronic)
Infumorph (IT morphine) approved (Medtronic)
Lioresal (IT baclofen) approved for spasticity (Medtronic)
MedStream (constant flow) pump approved (Codman – JnJ)
SynchroMed II pump receives FDA approval (Medtronic)
Prialt (IT Ziconitide) approved for chronic pain (Azur)Gablofen (IT baclofen) approved for spasticity (CNS Therapeutics)
Prometra Programmable Pump approved for IT pain (Flowonix)
MedStream Programmable Pump System approved for IT spasticity (Codman – JnJ)
IT Therapy Development History(Selected Highlights)
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Several Infusion Systems Available
for Targeted Drug DeliveryMEDSTREAM™ Programmable Infusion Pump and Control Unit
SynchroMed II Infusion Pump & N’vision Clinical Programmer
Prometra Pump and Programmer
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Common Features of ImplantableDrug Infusion Systems
Medtronic SynchroMed® II pump and N’Vision® Programmer shown above
Catheter Access Port – bypasses drug reservoir, used to check for catheter patency
Reservoir Refill Port – septum through which drug enters the pump upon refill
Titanium Housing – typically rigid outer housing that protects pump from mechanical damage
Drug Catheter – flexible tubing that runs from the pump with special tip for drug delivery
Programmer – used with ‘smart’ pumps, controls drug infusion rate, records drug history
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Interior of a Drug Infusion Pump
Pumph
ead
Drive G
ear
Battery
ElectronicsModule Refill Port
PumpheadDrive Gear
Rotor Assembly
(x-Ray)
Catheter Access Port
Images taken from a Medtronic SynchroMed® II Pump
Example of a battery-driven electro-mechanical pump, other pump models use a variety of drive and valve mechanisms to deliver drugs
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Infusion System Features:• Dose Accuracy
– 98%• Longevity
– >10 years• Weight
– 10% lighter• Easy refill• Designed to deliver any compound• Can deliver micro-doses• Can be programmed off
Flowonix Prometra - Pain
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Codman MedStream™ - SpasticityDrug Infusion Pump Programmer
Fill SensorRefill PortCeramic Drive
Valve
Filter Propellant GasFlowRestrictor
MEDSTREAM™ Control Unit
FluidFlow
Ceramic actuator (when charged) opens valve and allows fluid flow into catheter. Valve is closed when actuator is discharged.
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Deer, Krames et al, Neuromodulation: Technology at the Interface 11: 300-328, 2007
Concentrations & Doses of IntrathecalAgents Polyanalgesic Consensus Panel, 2007
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Local Anesthetics• Bupivicaine• Ropivicaine• Tetracaine
Adrenergic Agonists• Clonidine• Tizanidine
NMDA Antagonists• Ketamine
Other• Adenosine• Aspirin• Baclofen• Droperidol• Gabapentin• Ketorolac• Midazolam• Octreotide• Neostigmine• Ziconitide (Prialt)*
Non-Opioid Drugs used for Treatmentof Chronic Pain by the Spinal Route
*FDA approved for IT therapy for chronic pain
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IT Baclofen for Spasticity• Large % of refractory spasticity patients
• Intrathecal baclofen (ITB) has been used to treat spasticity since 1988, particularly dystonia secondary to cerebral palsy or traumatic brain injury
• ITB is an approved use of the Medtronic Infusion System
• The site of action is thoughtto be at the anterior horn cell
• It would be expected that intrathecal infusion would havegood access to this site
MotorCortex
SpinalCord
Medulla
AnteriorHorn
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Compartments of the Brain• The brain can be modeled as having
three compartments Blood ↔ CSF ↔ Brain
• CSF is held within a definedset of compartments> yellow – ventricles> light blue – subarachnoid &
intrathecal• Volume of CSF: 140ml• Rate of CSF production: 35ml/hr• CSF turnover: 4-6x/day• Blood flows through the brain at a rate
of 60 l/hr
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Blood
Brain CSF
Bulk Flow
DiffusionEpendym
a
Blood Brain Barrier Choroid Plexus
Arachnoid Villi
Schematic Equilibrium of Brain Compartments
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0
1
2
3
4
5
6
0 4 8 12 16 20 24
Bolus AdministrationContinuous Pump Infusion
Wasted DrugOverdoseToxicityAdverse
effects
Efficacy
Time (hours-days)
Dru
g C
once
ntra
tion
UnderdoseLoss of Effect
Advantages of Continuous Infusion over Bolus Drug
Delivery
Noeffect
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Efficacy of Opioids in Cancer Pain – by Route of Administration
TherapyExcellent
Outcome (%)Studies
(Patients)UnsatisfactoryOutcome (%)
Studies (Patients)
Intracerebro-ventricular 73 8 Studies
N = 295pts 7 8 StudiesN = 295pts
Epidural 72 14 StudiesN = 349 13 25 Studies
N =794
Subarachnoid 62 10 StudiesN = 146pts 11 18 Studies
N = 333pts
Analgesic Outcome:
adapted from Ballantyne, Carwood 2009
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ICV Baclofen for Dystonia (Albright)Results:• 8 of 10 patients responded to the treatment• 2 non-responding patients also did not
respond to previous IT treatment• 3 pump-related adverse effects
Albright et al, Neurosurg Pediatrics 3:000–000, 2009
MotorCortex
SpinalCord
Medulla
PrimaryMotor Area
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Comparison IT and ICV Chemotherapy• CSF Chemotherapy used for 30
years by IT and ICV routes
• Useful for overcoming the BBB limitation on distribution of drugs and metabolites
• PK studies demonstrate high CSF drug concentrations can be achieved
• Effective for treatment of meningeal leukemia in humans
• Not as effective treatment for deep parenchymal distribution into the brain
Blasberg et al, Cancer Treat Rep 61:1977
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Topotecan ICV Advantage
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Key Elements for Drug : DeviceTherapy Development
TherapySuccess
Drug/Biologic
DeliveryPrinciples
cRcDctc
v
Device
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Around the BBB: Intracerebroventricular(ICV) Drug Delivery
Lateral view of brain with the cerebral ventricles shown in blue
Cross section of the brain shown with a catheter placed in the lateral ventricle (blue)
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Technology: CombiningDrugs & Pumps for Brain Delivery
Several benefits of delivering drugs directly to the brain fluid: • Significantly Lower dose
Less risk of side effects and organ toxicity Improved Tolerability
• Target effectiveness Consistent drug levels lessens difficulty
finding therapeutic ratio for an each patient “Last pass metabolism”: Drugs do not go first
through GI tract, then liver, etc…• Adherence - Overcome patients inability to take
medication• Additional drug options for refractory disease -
targeted nature of the delivery platform allows additional drug candidates
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Indication: Refractory Epilepsy
Drug: ICVrx001
Device: Implanted Drug Infusion Pumpand ICV Catheter
Duration: Life-Long (chronic-intermittent)
Desired Effects: Reduce seizure frequency and severityReduce adverse events
Treatment Effect: Palliative
Stage: Early Clinical
Intracerebroventricular Drug TherapyProduct Concept: ICV Drug Therapy for Epilepsy
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• Significant unmet medical need
• Large, and growing, patientpopulations
• Substantial revenue potential
• Blood Brain Barrier (BBB) stops most drugs from entering CNS
• Combined with other therapeutic advantages, BBB creates need for targeted drug delivery
36.6M Patients/20 disorder$95.5B Market across 7MM
>21% share of Pharma
Factors Driving Site-DirectedDrug Delivery for Treating CNS Disease
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Drugs-Biologics• small molecule• peptide - protein• oligonucleotides• plasmids
Implantable Pumps• targeted delivery• controlled delivery
The Future of Medicine:Drug-Device Therapies
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Thank You …..
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Clinical Trials of IntracerebroventricularMorphine Therapy