mike iadarola-ion channel retreat june 2012 short version upload

7/28/2019 Mike Iadarola-Ion Channel Retreat June 2012 Short Version Upload

1/19

- TRPV1 agonistsa) Preclinical research

b) Clinical trial in cancer pain

c) Osteoarthritis

- TRPV1 positive allosteric modulators

Multiple Pathways for Pain Control Using TRPV1

Ion Channel Agonists and Positive Allosteric

Modulators

Michael Iadarola, Ph.D.

Neurobiology and Pain Therapeutics Section (NPTS)

Laboratory of Sensory Biology, NIDCR

National Institutes of Health, USA


2/19

Neuronal Pathways & Analgesic Targets

Central or Peripheral nervous system?

PeripheralNo CNS side

effects,

Can produce

insensitivity

to pain

CentralPossible CNS side

effects

Level of relief from

severe pain

Neurosurgical Lesions for Pain Relief: Antero-lateral Quadrant Cordotomy (ALQ)

Cut here


3/19


4/19

TRPV1 Agonists ?If agonists activatethe ion channel, wont that cause pain?

Yes: a) 8%capsaicin patch: pretreat with 4% lidocaine patch and oxycodone after.

Backonja et al., Lancet Neurol 7:110612, 2008.b) Iadarola et al., Neural activation during acute capsaicin-evoked pain and allodynia

assessed with positron emission tomography. Brain 121:931-947, 1998.

Literally cut the connection

between the body and the

spinal cord: Permanent

intervention

Can we use this

Therapeutically?

Yes: agonist activation leads

to a calcium overload. This

produces a highly selective

Lesion of pain fibers or neurons

Ca++

TRPV1 Model constructed by Krisztian Kaszas, NPTS, NIDCR


5/19

Molecular Targeting of TPRV1

Using Agonists

Capsaicin Resiniferatoxin (RTX)

Karai L, Russell JT, Iadarola MJ, Olah Z: J Biol Chem. 279:16377-16387, 2004.


6/19

Con 0.5

5 15

RTX-induced Fragmentation of ER and Mitochondria

Laser confocal microscopy at 24 hrs after transfection; TRPV1eGFP: Green fusion protein labels ER and

plasma membrane; Mitochondria: MitoTracker Red dye.

No bystander effect: cells without the receptor (red only) are unaffected

Olah Z, Karai L and Iadarola MJ: J Biol Chem 276: 31163-31170, 2001.

eGFP

TRPV1-eGFP fusion


7/19

Agonist Selectivity

TRPV1: ENRICHED EXPRESSION IN SENSORY GANGLIA

1 Cerebellum2 Cortex

3 Dorsal Root Ganglion

4 Hippocampus

5 Hypothalamus

6 Substantia Nigra7 Spinal Cord

8 Striatum

9 Trigeminal Ganglion

10 Blank

TRPV1

GAPDH

1 2 3 4 5 6 7 8 9 10

RT-PCR (30 cycles) Rat Brain and Sensory Ganglia


8/19

Animal studies of RTX

Non-clinical rodent studies: Established specificity, dose range,

duration of action and route of administration

Canine modelthat closely resembles human situation.- UPenn School of Veterinary Medicine, Dr. Dorothy Cimino Brown.

- Client dogs with naturally occurring osteosarcoma

- Candidates for euthanasia. Why? Poor pain control

- Owner can assess higher order function

Profound analgesia, durable, resistant to disease progression, no personality change,

no impact on bladder or bowel function, no impact on motor function.


9/19

Long term pain control in bone cancer

Brown DC, Iadarola MJ, et al., Anesthesiology 103:1052-1059, 2005.


10/19

Analgesic & Anti-inflammatory Medication Administered to Dogs with Bone Cancer

Dog Prior to RTX Administration 2 Weeks Following RTX Administration

1 Carprofen 100mg every 12 hours

Prednisone 10 mg every 12 hours

Prednisone 2.5 mg every 12 hours

Dose decreased

2 Piroxicam 10 mg every 24 hours Piroxicam 10 mg every 48 hours3 Codeine 90 mg every 8 hours

Piroxicam 10 mg every 24 hours

None

4 Prednisone 20 mg every 12 hours Prednisone 20 mg every 12 hours

5 Etodolac 450 mg every 12 hours Etodolac 450 mg every 12 hours

6 Carprofen 75 mg every 12 hoursButorphanol 5 mg every 12 hours

None

7 Piroxicam 20 mg every 24 hours None

8 Carprofen 100mg every 12 hours None

9 Deracoxib 100 mg every 24 hours Deracoxib 100 mg every 24 hours

10 Codeine 120 mg every 8 hours None

11 Deracoxib 100 mg every 24 hours None

14 Deracoxib 100 mg every 24 hours

Codeine 30mg every 6 hours

Deracoxib 50 mg every 24 hours

Dose Decreased

67%of the

dogs either

discontinued

or decreasedstandard

analgesic

drugs

Brown DC, Iadarola MJ, et al., Anesthesiology 103:1052-1059, 2005.


11/19

1) Raw Material: Latex from

Euphorbia resinifera a

cactus-like succulentfrom Morocco

3) RTX Toxicology

Two species: CompleteNIDA Collaboration

4) Clinical protocol: Single administration of intrathecal

resiniferatoxin for treating severe refractory pain

associated with advanced disease.

2a) Large scale cGMP production

of RTX NIDA Collaboration

2b) Formulation of RTX for injectionNIH Pharmacy

5) IND to FDAAnimal and cellular

toxicology data,

Drug master file,Stability, etc

NIDA Collaboration

6)Phase IClinical trial

at NIH

Recruiting

NOW

Steps to Human Clinical Trial of RTX for Cancer Pain

http://clinicaltrials.gov/ct2/show/NCT00804154

Iadarola MJ and Mannes AJ: Curr Top Med Chem. 11(17):2171-2179, 2011

Protocol 09-D-0039:

A Phase I Study of the Intrathecal

Administration of Resiniferatoxin

for Treating Severe Refractory Pain

Associated With Advanced Cancer


12/19

Eligibility Criteria:Pain in lower half of body

Cauda

Equina:

site of

lumbar

punctureand

catheter

insertion

RTX injection procedure: lumbar puncture

Dermatome map of body

L5

L4

L3

L2

L1

T12

Affecteddermatomes

http://clinicaltrials.gov/ct2/show/NCT00804154

Protocol 09-D-0039: A Phase I Study of the Intrathecal Administration of Resiniferatoxin

for Treating Severe Refractory Pain Associated With Advanced Cancer


13/19

Peripheral RTX Administration

Central Administration

PERMANENTcuts the axon or kills the cell

Peripheral Administration

TRANSIENTNerve terminals die back and re-grow

Routes:Topical (cornea)

Intra-joint

Perineural

Subcutaneous

Primary

afferent

neuron

Terminal in

spinal cordTerminal

In body

Indications:

Corneal pain

Osteoarthritis

Post-injury neuropathic pain with

A localized site of origin or trigger zone

Certain types of low back pain


14/19

TRPV1 Allosteric Modulators

Objective: new approach to TRPV1 based analgesic agents

Roadmap Grant R03 MH089480, HTS for Identifying Allosteric

Modulators of the TRPV1 receptor.

Positive allosteric modulators. Concept: impose an activity-

dependent mode of action to enhance process of nerve terminal

inactivationLead compounds

TRPV1 PAMs should be selective for areas actively experiencing tissue damage or inflammation

peripheral generators that would be sites of endovanilloid production and low pH.


15/19

MRS-1477: a TRPV1 positive allosteric modulator

- capsaicin + capsasicin

Calcium imaging in primary DRG neurons

Roh EJ, Keller JM, Zoltan Olah Z,Iadarola MJ, Jacobson KA: Bioorganic & Medicinal Chemistry 16:93499358, 2008


16/19

Positive Allosteric Modulation of TRPV1 with MRS1477Positive modulator effects on orthosteric agonist and H+ ion

Ca++Ca++

Kaszas K, Keller JM, Coddu C, Mishra S, Hoon M, Stojilkovic S,Jacobson KA, Iadarola MJ:

J Pharmacol Exp Ther 340: 152-160, 2012


17/19

1477 produces a long-term nerve terminal inactivation

Thermal testing of the paw for A-delta or C-fiber integrity following combination

Injectnion of capsaicin (the TRPV1 agonist) and MRS1477 (the TRPV1 PAM)

A-delta stimulation

Lebovitz E, et al., Molecular Pain, in press


18/19

SummaryA. TRPV1 agonists can be used in many different ways.

Two examples are:

- Intrathecal administration of RTX to treat pain from advanced cancer

- Peripheral administration into areas of inflammation or nerve damage.

B. TRPV1 PAMs may also be versatile analgesic agents.

- The duration of action occurs over several days in our experimental model

- It may be possible to administer them systemically or by local injection

- They have an activity-dependent component to their action

- The role of endovanilloids requires further investigation.


19/19

Acknowledgements

Many of my colleagues were, and still are, involved in bringing the work with RTXfrom the bench to the bedside. The development of the PAMs is part of the next

phase of TRPV1-based drugs.

RTX

NIDCR: Zoltan Olah, Laszlo Karai, Ofer Wellisch, Andrew Mannes, Jason Keller

University of Pennsylvania: Dorothy Cimino Brown

NIH Pharmaceutical Development Section: George Grimes

NIDA: Nate Appel, Robert Walsh, Nora Chiang, Moo Park, Marta DeSantis, Jim Terrill

PAMs

NIDCR: Krisztian Kaszas, Jason Keller, Evan Lebovitz, Zoltan Olah, Ken Jacobson,NCATS, NCGC: Noel Southall, Erika Englund, Juan Marugen, Steve Titus

This work was supported by the Intramural Research Program NIH, NIDCR and

Molecular Libraries Screening Grant, 1 R03 MH089480, HTS for Identifying

Allosteric Modulators of the TRPV1 receptor.

mike iadarola-ion channel retreat june 2012 short version upload

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