Osteoarthritis (OA): in vitro and animal models - PowerPoint PPT Presentation

Osteoarthritis (OA): in vitro and animal models

James Witter MD, PhD

Division of Analgesic, Anti-inflammatory and Ophthalmic Drug Products (HFD-550)

Center for Drug Evaluation (CDER)

Food Advisory Committee Meeting

June 7, 2004

Human

Animal

Client

(companion)

Experimental model

Histology

cell

enzyme

Osteoarthritis Initiative

NIH/FDA/Industry/Academia

February 28-29, 2000

• $76 billion, direct/indirect health care costs
• 68 million lost work days (pain and loss of function)
• clinical OA (MD diagnosis)
• 12.1% of US or 21 million people
• total joint replacements
• 494,000/yr (hip-knee)
• market size
• symptoms- $4.0 billion
• structure- $3.5 billion

• is OA inevitable part of aging?
• certain joints in most people normal in old age
• what is the etiology of OA?
• likely multiple, few examples…
• genetic-developmental
• overuse
• acute and chronic trauma
• underuse
• atrophy
• primary (idiopathic) vs. secondary

Biochemical changes

Structural changes

Pain* and other signs and symptoms (OA)

Functional limitation*

Reduced quality of life*

Surgical replacement*

* important to the patient

FDA may grant marketing approval for a new drug product on the basis of adequate and well-controlled clinical trials establishing that the drug product has an effect on a surrogate endpoint that is reasonably likely, based on epidemiologic, therapeutic, pathophysiologic, or other evidence, to predict clinical benefit or on the basis of an effect on a clinical endpoint other than survival or irreversible mortality.

• A surrogate endpoint of a clinical trial is a laboratory measurement or a physical sign used as a substitute for a clinically meaningful endpoint that measures directly how a patient feels, functions, or survives
• Changes induced by a therapy on a surrogate endpoint are expected to reflect changes in a clinically meaningful endpoint
• Only valid if the effect on the surrogate leads to a clinical benefit

• Surrogate endpoints are candidates for drug approval
• Biomarkers do not have the same regulatory implication
• Surrogates may be biomarkers, but not all biomarkers are surrogates.

Clinically Meaningful Outcome

Surrogate marker

Biomarker

• currently JSN (knee/hip) by X-ray accepted as surrogate
• trial length: at least one year
• include endpoints of pain, patient global, and patient reported outcome
• can structure “stand alone”?

• “Normalize” the X-ray (stand alone)
• Improve JSN over baseline (stand alone)
• reflects new or regrown “physiologic” cartilage
• Slow JSN by “clinically relevant amount”
• may not need symptom evidence for approval
• approval contingent on commitment to define the actual symptom benefit in phase 4 studies
• Slow JSN by < “clinically relevant amount”
• subpart H approach
• JSN is surrogate

Structure of Hyaline Cartilage

• chondrocytes in abundant extracellular matrix
• 65-80% water
• 20-35% dry weight is structural macromolecules
• type II collagen ~50%
• aggrecan ~ 25%
• glycosaminoglycans (GAGs)
• chondroitin sulfate (4 vs. 6)
• keratan sulfate
• other types of collagens (IX, XI)
• other proteoglycans
• hyaluronic acid

• cartilage (hyaline, fibrocartilage)
• aneural avascular alymphatic
• menisci (medial, lateral)
• tendons, ligaments,capsule
• bone
• synovial
• membrane
• fluid
• muscles

Fixed Flexion

Extended

Knee Radiography Techniques

Semi-flexed Fluoroscopy

Semi-flexed MTP

Schuss

• conventional knee X-ray not reproducible
• solution: (Buckland-Wright technique)
• Semi-flexed AP view
• Fluoro-assisted to allow to superimpose anterior and posterior margins of medial tibial plateau
• To provide alignment of plateau and x-ray beam
• Magnification-corrected JSW using xJSW software
• problem: Not reproducible in clinic for
• Entry criterion
• Monitoring of disease

• maintain matrix equilibrium/environment
• Chrondrocyte highly sensitive to feedback
• anabolic
• proteoglycans and GAGS
• catabolic
• matrix metalloproteinases (MMP)
• biomarkers
• cell-cell and cell-matrix interactions
• loading stresses
• nutrients and waste removal
• temperature
• core (37°C) vs. ankle joint (29°C)

• without glucose, glucosamine sole source of glycosaminoglycans (GAGs) for cell
• with glucose
• strong competitive inhibitor to utilization of glucosamine to produce GAGs
• with glucosamine
• do not stimulate production of GAGs
• higher concentration produced less GAGs
• what are likely levels of glucose, glucosamine at level of human cell?

• pain
• primary clinical symptom
• surgical intervention
• not mimic human situation
• species differences
• 4 vs. 2 legs
• biochemistry
• underuse
• muscle weakness (elderly women)

PainArthritis Advisory CommitteeJuly 29-30, 2002

• studied directly (by patient) in humanOA
• WOMAC for hip and knee
• studied indirectly (veterinarians) in animalOA
• chronic
• lameness (function)
• acute
• vocalization
• behavioral changes
• decreased appetite
• increases or decreases in activity
• physiologic changes (pulse, blood glucose)

• Primary efficacy endpoints:
• Pain
• Function
• Patient global
• Trial length:
• 3 months

1. Walking on flat surface

2. Going up or down stairs

3. At night while in bed

4. Sitting or lying

5. Standing upright

• iodoacetate
• chicken
• papain
• guinea pig, mouse
• chymopapain
• dog
• collagenase
• mouse
• TGF-ß
• mouse

• anterior cruciate ligament transection
• unilateral or bilateral
• dog, rabbit
• meniscectomy
• rabbit, guinea pig
• immobilization
• rabbit, dog
• patellar contusion
• rabbit

• Age/obesity
• Hartley guinea pig
• Genetic
• unidentified
• mouse, primate
• Transgenic mice
• type IX or II collagen mutation
• hip dysplasia
• dog (purebred vs. mixed bred)

• chondrocytes can repair damage
• hypertrophic cartilage
• increased GAGs
• true in humans, rabbits and Rhesus macaques
• neurogenic acceleration
• dorsal route ganglionectomy
• more rapid cartilage damage
• not good model for primary (idiopathic) OA
• homeostatic phase of hypertrophic repair differs
• importance of periarticular muscle
• immobilized joint has atrophic loss of GAGs
• quadriceps weakness in elderly women

Pre

Pro Catalytic Hemopexin-like

Fibronectin 1(V) Transmembrane

MMPPre Pro Cat Fn1(V) TmHpx

Matrilysin

Collagenase-1,-2,-3

Stromelysin-1,-2,-3

Macro elastase

MT MMP-1 to -4

Gelatinase A

Gelatinase B

• hydrolyze relevant matrix substrates in vitro
• upregulated by disease mediators (IL-1, TNF)
• in situ hybridization and immunofluorescence at sites of tissue degeneration
• signature cleavage fragments in vivo
• Collagen neoepitopes
• blockage by natural compounds and selective MMP inhibitors in vitro models

CollagenaseHumanRatMouseRabbitDog

1 Yes No No Yes Yes

2 Yes ? Yes Yes ?

3 Yes Yes Yes Yes Yes

Therapy X (mg/kg/d)

1

3

10

Parameter

Normal

Sham

Vehicle

2.1

Fibrillation

0.1

0.1

3.6

4.1

2.7

Fissures

0.1

0.1

3.5

4.5

2.1

0.7

Erosions

0.0

0.0

2.9

2.9

1.0

0.9

Global

0.3

0.5

13.1

15.9

8.8

5.5

p < 0.01

Treatment Area Composite

Vehicle 32  10 1.7  0.6

Low Dose X 22  7.7 1.4  0.8

High Dose X 19  8.4 1.0  0.8

Limit joint destruction

Results (clinical trials)

MMP inhibitors

No effect in RA or OA

Some stopped due to safety data in oncology trials

Stiffness/pain particularly in shoulders and hands

Bisphosphonates

Suggestion of efficacy in phase 2 trial, not confirmed in phase 3 trials (ACR-Orlando, 2003)

Timing of Approval and:

Structural Benefit

Clinical Benefit

RA

Drug approval

Time

OA

OA: structural modifier

OA: JSN progression

Rapid

JSN

Slow

No change

b

a

c

a

Time

• to facilitate and standardize development of disease-modifying agents
• consists of the following key elements:
• pain
• function
• radiographic endpoints
• idea that agreed upon endpoint of joint failure reached (and surgery may occur)

Osteoarthritis: The “Joint Organ”

Total Joint Replacement

Clinical

Function

3 or 4

Pain

2

Surrogate

Tendon/Ligament

1

Synovium

Bone

Drug development

phase

Biomarkers

Cartilage

…validation of a molecular target in human disease can be obtained only

after positive results are obtained in Phase III clinical trials in humans.

Ken Brandt, Biorheology 39 (2002) 221-235

Human OA

In vitro

animal