1. rhBMP-2: origin, biology and preclinical safety
Presentation G ver
4/14/2017
rhBMP-2: origin, biology and preclinical safety
Gerard E. Riedel, Ph.D.
Wyeth-Genetics Institute, Inc.
Cambridge, Massachusetts USA

2. rhBMP-2 =
recombinant human bone morphogenetic protein-2

3. Origin of rhBMP-2 The gene for human BMP-2 was isolated
This gene was inserted into a chromosome of a mammalian cell
This cell line grows in large culture vessels and secretes rhBMP-2 into the media
rhBMP-2 is purified, vialed and freeze-dried

4. Presentation G ver
4/14/2017
Properties of rhBMP-2
Member of “growth and differentiation” protein family
Endogenous BMP-2 is active in bone repair and in embryonic development
Homodimeric, glycosylated protein that is highly conserved across species
Osteoinductive in animals and humans

5. rhBMP-2 induces bone rat ectopic implant assay
14 days
post-implantation

6. Mechanism of bone induction
Chemotaxis/ proliferation
Differentiation of mesenchymal cells
Bone induction
trabecular, woven bone
remodels appropriately
Increased vascularity

7. Mechanism of rhBMP-2 action
Cell biology
Responsive cell types, receptors and signal transduction pathways identified
Bone induction biology
Local administration is required

8. Implantation of rhBMP-2 requires a matrix
Delivers rhBMP-2 to surgical site
Augments rhBMP-2 retention at site
Provides a compatible environment for bone induction

9. Matrix = ACS (absorbable collagen sponge)
Commercially available in US since 1981
Approved PMA (Integra LifeSciences)
Implantable hemostatic agent
Extensive experience of safe use
Bovine tendon Type I collagen
Manufacturing process meets/exceeds all US guidance

10. ACS = Helistat®

11. rhBMP-2/ACS preparation
Presentation G ver
4/14/2017
rhBMP-2/ACS preparation
WFI
rhBMP-2
rhBMP-2 solution
ACS

12. rhBMP-2/ACS & LT- CAGE™ device

13. ACS augments rhBMP-2 retention at implantation site
Orthotopic model (rabbit ulna)
Radiolabelled rhBMP-2
Gamma camera scintigraphy
Validated method

14. rhBMP-2 retention with ACS
Presentation G ver
4/14/2017
rhBMP-2 retention with ACS
% initial dose
days

15. Safety information rhBMP-2/ACS studies ADME studies rhBMP-2 studies
implant safety studies
ADME studies
rhBMP-2 studies
Tumor biology studies
Systemic toxicity studies
Reproductive toxicity studies

16. rhBMP-2/ACS safety studies
Three anatomic sites
craniofacial, long bone, spine
Meyer et al Spine 24:
Dosing >>> therapeutic range (species-adjusted)
Results: no systemic effect
local effects = rhBMP-2 bioactivity

17. Biodistribution studies of rhBMP-2/ACS
Two species (rats, rabbits)
Two implant sites
ectopic or long-bone (+/- osteotomy)
Results:
rhBMP-2 is released slowly from implant site
low systemic availability (rat long-bone model)
maximum rhBMP-2 detected = 0.1% of dose

18. rhBMP-2 is slowly released from implantation site

19. ADME studies of rhBMP-2 Pharmacokinetics/biodistribution
rats (adults and juveniles) and NHP
IV administration
Results: rhBMP-2 is cleared rapidly from the circulation, primarily through the liver, and rapidly degraded/excreted into urine

20. rhBMP-2 is rapidly cleared from the systemic circulation

21. slow release from implant site + rapid clearance from circulation
low rhBMP-2 systemic exposure

22. Tumor biology studies Screening studies
Some tumors express BMP-2, BMP receptors
No evidence that BMP-2 initiates tumors
No cytotoxic/mutagenic activity in vitro
No evidence of abnormal cell biology in implant toxicity studies
Pharmacology studies (in vitro)

23. Effect on tumor growth (in vitro)
51 tumor cell lines tested
3: growth promotion (in serum-free media) [pancreas (2), prostate]
48: no effect or inhibition
71 primary tumor isolates tested
71: no effect or inhibition
Inhibition is not sufficient for therapy

24. Additional tumor studies (FDA consultation)
1. Screen tumor cells
for BMP receptor
messenger RNA
2. Assess effect on
tumor cell growth
in vitro (cell culture)
3. Assess effect on
tumor cell growth
in vivo (xenograft)

25. rhBMP-2 toxicity studies
Systemic toxicity of rhBMP-2
single or repeat IV dosing, two species
exposure > 1000x expected in patients
Reproductive toxicity of rhBMP-2
repeat IV dosing, two species
fertility and teratology
Results: no systemic effect

26. Additional safety studies
Tripartite guideline safety studies
in vivo, in vitro
cytotoxicity, mutagenicity, others
General safety studies
in vivo, IV administration
behavior, locomotion, other body functions
Results: no effect

27. New studies (FDA consultation)
Focus: better understanding of an immune response to rhBMP-2
New clinical assay
measure all human antibody isotypes (current assay measures human IgG)
Neutralization assay
ability of antisera to block rhBMP-2 activity

28. Preclinical safety findings
Presentation G ver
4/14/2017
Preclinical safety findings
No systemic effects
attributed to low systemic exposure
local effects = osteoinduction by rhBMP-2
No toxicity detected
Safety assessment supports use of InFUSE™ Bone Graft