The Future of Bone Anabolics:Inhibition of Sclerostin in theTreatment of Osteoporosis

Cesar E. Bogado, PhDCesar E. Bogado, PhDInstituto de Investigaciones MetabólicasInstituto de Investigaciones Metabólicas

Buenos AiresBuenos Aires

V Latin American Forum on Musculoskeletal HealthSalvador, Bahía, Brazil

April 20 th-21st 2012

Osteoporosis Treatment:Targeting Bone Remodeling Pathways

• Imbalance of Bone Remodeling- Lead to Osteoporosis- Offer potential targets for therapy

• Bone Remodeling- Resorption

√ RANK, RANKL, OPG- Formation

√ Wnt / LRP5 / β- catenin

Abbreviations: LRP, low-density lipoprotein receptor-related protein; OPG, osteoprotegerin;RANK, receptor activator for nuclear factor kappa B; RANKL, RANK-ligand

Wnt/LRP5/ ββββ- catenin Pathway in Bone Formation

• Wnt/LRP5/ ββββ-catenin pathway is essential

- Osteoblast proliferation, differentation andsurvival

- Activity during a phase of bone formation

• Natural inhibitors of the Wnt/LRP5/ ββββ-catenin pathway

- Dikkopf (Dkk): made by mieloma cells- Soluble decoy receptors, proteins: WIF, sFRP- Sclerostin : product of osteocytes

Abbreviations: sFRP, secreted frizzled-related protein; WIF, Wnt inhibitory factor.

Wnt

Frizzled

Liganded State

APC

axinDsh

Frat-1

WntWIF WntsFRP

Gsk3

ββββ-Cateninββββ-Catenin

ββββ-Catenin

ββββ-Catenin p300/CBP

SMRT/ NCoR

Tcf/Lef

Altered Transcription of Genes

Nuclear Localization

Nucleus

BONE FORMATION

OSTEOBLAST

Shoback D. J Clin Endocrinol Metab.2007;92:747-753.

Cytoplasm

Wnt/ ββββ-catening Signaling Regulates Ostogenesis

Krishnan V., et al J Clin Invest 2006, 116: 1202-1209

Wnt

Frizzled

Liganded State

APC

axinDsh

Frat-1

WntWIF WntsFRP

LRP

5/6K

remen

Dkk

LRP

5/6

SOST

APC

Gsk3

Frizzled

P

Unliganded State

Gsk3

ββββ-Cateninββββ-Catenin

ββββ-Catenin

ββββ-Catenin p300/CBP

SMRT/ NCoR

Tcf/Lef

Altered Transcription of Genes

Nuclear Localization

Nucleus

BONE FORMATION

OSTEOBLAST

Shoback D. J Clin Endocrinol Metab.2007;92:747-753.

Cytoplasm

LRP 5/6

Gsk3axin ββββ-Catenin

P

ProteosomalDegradation

Sclerostin Secreted by Osteocytes Negatively Regulates Bone Formation

Pre-OsteoblastLining Cells

Mature Osteoblasts

MesenchymalStem Cells

Sclerostin

X X

BoneOsteocyte

X XNew Bone

Ott SM. J Clin Endocrinol Metab. 2005;90:6741-6743. Semenov MV, et al. J Biol Chem. 2006;281:38276-38284. Semënov M, et al. J Biol Chem. 2005;280:26770-26775. Li X, et al. J Biol Chem. 2005;280:19883-19887.

Targeted Deletion of the SOST Gene in Mice Results in Increased Bone Formation and Strength

Li X et al J Bone Miner Res 2008, 23 (6): 860- 869

Inhibition of Sclerostin by Monoclonal Antibody

MesenchymalStem Cell

OsteoprogenitorCell

WITHOUT Sclerostin Antibody WITH Sclerostin Antibody

MesenchymalStem cell

OsteoprogenitorCell

Bone

Pre-Osteoblast

Osteocyte

Scl-MAb

Sclerostin

Osteocyte

Pre-Osteoblast

Sclerostin Antibody Treatment in Aged OVX Rats(A Model of Post menopausal Osteoporosis)

• Six-month-old female Sprague-Dawley rats were either sham-operated or OVX and left untreated for 13 months.• OVX rats injected sc with PBS (n=12) or a murine• OVX rats injected sc with PBS (n=12) or a murineanti-sclerostin mAb (n=12) at 25 mg/kg, twice a week for 5 weeks. Sham-operated rats received PBS.• DXA BMD, µCT, histomorphometry and strength testing

Scl-Ab Treatment Increases areal BMD in Aged OVX Rats

Data represent mean ± SE for 11–12 rats/group.

*p < 0.05, **p < 0.01, and ***p < 0.001 vs. OVX + vehicle. ^p < 0.05 and ^^p < 0.01 vs. Sham + vehicle.

Li X. et al, J Bone Miner Res 2009, 24(4): 578- 588

Scl-Ab Treatment in OVX Rats3-D µCT Images of the Distal Femur

Li X. et al, J Bone Miner Res 2009, 24(4): 578- 588

Scl-Ab Treatment Restores Tb BMD and BV/TB Back to Sham Levels in OVX Rats

Data represent mean ± SE for 11–12 rats/group.

***p < 0.001 vs. OVX + vehicle.

Li X. et al, J Bone Miner Res 2009, 24(4): 578- 588

Scl-Ab Treatment Increases Tb BV/TV and Bone Formation as Assessed by Histomorphometry

Data represent mean ± SE for 8 rats/group.

*p < 0.05 and ***p < 0.001 vs. OVX + vehicle. ^^p < 0.01 and ^^^p < 0.001 vs. Sham + vehicle.

Li X. et al, J Bone Miner Res 2009, 24(4): 578- 588

Scl-Ab Treatment Increases Bone Strength in Aged OVX Rats

COMPRESSION TESTING FOUR-POINT BENDING TEST

Data represent mean ± SE for 12 rats/group.

LUMBAR VERTEBRAE FEMORAL MIDSHAFT

**p < 0.01 and ***p < 0.001vs. OVX + vehicle.^^p < 0.01 and ^^^p < 0.001vs. Sham + vehicle.

Li X. et al, J Bone Miner Res 2009, 24(4): 578- 588

Osteoclast Surface is Decreased in Scl-Ab-Treated OVX Rats

Data are expressed as the mean ± SE for n = 9–12/group.* p < 0.01, ‡ p < 0.001, and ¶ p < 0.05, compared with vehicle-treated OVXGroup. † p < 0.05 and § p < 0.001 compared with sham control group.

Li X. et al, J Bone Miner Res 2009, 24(4): 578- 588

Scl-Ab Treatment Increases Periosteal and Endocortical Bone Formation in OVX Rats

Data represent mean ± SE for 9–12 rats/group.***p < 0.001 vs. OVX + vehicle; ^^^p < 0.001 vs. Sham + vehicle.

Li X. et al, J Bone Miner Res 2009, 24(4): 578- 588

Sclerostin Antibody Treatment in Aged OVX Rats(A Model of Post menopausal Osteoporosis)

• Short-term administration of a sclerostin-neutraliz ing antibody resulted in marked increases in bone formation, bone mass and bone strength.• Bone volume was increased in both the trabecularand cortical bone compartments.and cortical bone compartments.• Bone formation was increased on the periosteal and endocortical surfaces.• Osteoclast surface was decreased, suggesting an absence of the coupling between osteoblasts and osteoclasts.

Sclerostin Antibody Treatment in Aged Male Rats(A Model of Male Osteoporosis)

• Sixteen-month-old, gonad-intact male Sprague-Dawley rats were injected subcutaneously with vehicle or Scl-Ab at 5 or 25 mg/kg twice per week for 5 weeks (9–10/group).

• DXA BMD, µCT, histomorphometry and strength testing

Scl-Ab Treatment Increases areal BMD in Aged Male Rats

LUMBAR VERTEBRAE 1-5 FEMUR-TIBIA

Data represent mean ± SEM for 7 to 10 rats/group.

a p< .05 versus vehicle. b p< .05 versus 5 mg/kg group.

Li X. et al, J Bone Miner Res 2010, 25(12): 2647- 2656

Scl-Ab Treatment in Aged Male Rats3-D µCT Images of the Lumbar Vertebral Body, Distal

Femur and Femoral Neck

Greater trabecular thickness and trabecular bone volume at all three sites in rats treated with Scl-AbGreater cortical thickness in L5 with Scl-Ab treatment.

Li X. et al, J Bone Miner Res 2010, 25(12): 2647- 2656

Scl-Ab Treatment Increases Both Trabecular and Cortical Bone Formation in Aged Male Rats

Fluorescent micrographs of (A ) sections from the trabecular region of the proximal tibial metaphysisand (B) cortical bone sections from the tibiofibula junction

Greater mineralizing surface at both the endocortic al and periosteal surfaces in Scl-Ab-treated rats

Li X. et al, J Bone Miner Res 2010, 25(12): 2647- 2656

Scl-Ab Treatment Increases Bone Strength in Aged Male Rats

Data are presented as mean ± SEM

a p<.05 versus vehicle.b p<.05 versus 5 mg/kg.

Li X. et al, J Bone Miner Res 2010, 25(12): 2647- 2656

Sclerostin Ab Treatment in Aged Male Rats(A Model of Male Osteoporosis)

• Short-term inhibition of sclerostin using a neutralizing antibody in aged male rats increased b one formation, bone mass and bone strength.• Bone formation was increased in the trabecular, endocortical and periosteal compartments.endocortical and periosteal compartments.• Short-term sclerostin inhibition increasedbone strength at the femoral neck, a principal site ofosteoporotic fracture in humans.• The increase in bone formation was not associated with increases in serum CTX-1 or in osteoclast surfa ce.

Bone Anabolic Effects of Scl-Ab are not Blunted by Pre- or Co-treatment with ALN in

OVX RatsExperimental DesignGroups (n=10) First 6 weeks Second 6 weeks

Sham-vehicle Vehicle N/A

OVX-vehicle Vehicle N/A

OVX-ALN ALN N/AOVX-ALN ALN N/A

Sham-vehicle/vehicle Vehicle Vehicle

OVX-vehicle/vehicle Vehicle Vehicle

OVX-vehicle/Scl Ab Vehicle Scl-Ab

OVX-ALN/Scl Ab ALN Scl-Ab

OVX-ALN/Scl Ab + ALN ALN Scl-Ab + ALN

Sprague Dawley rats were sham operated or OVX and left untreated for 3.5 monthsALN: 28 mg/kg, twice weekly.Scl-Ab: 25 mg/kg, once weekly

Li X. et al, Endocrinology 2011,152 (9): 3312-3322

Areal BMD Changes Induced by Scl-AbTreatment in OVX Rats Pre- or Co-treated with

ALN

Data are expressed as the mean ± SEM

a, P < 0.05 compared with the age-matched sham group;b, P < 0.05 compared with the age-matched OVX vehicle group;c, P < 0.05 compared with the OVX-Vehicle/Scl-Ab group.

Li X. et al, Endocrinology 2011,152 (9): 3312-3322

Bone Formation Rate in OVX Rats Pre- or Co-treated with ALN

BFR/BS a t Trabecular Bone of 3rd Lumbar Vertebral Body

Data represent mean ± SEM for 10 rats per groupa, P < 0.05 compared with the respective sham control group;b, P < 0.05 compared with the respective OVX control group.

Li X. et al, Endocrinology 2011,152 (9): 3312-3322

Bone Strength in OVX Rats Pre- or Co-treated with ALN

Bone strength parameters for the 5th Lumbar Vertebral body

Data represent mean ± SEMa, P 0.05 compared with the respective sham control group;b, P 0.05 compared with the respective OVX control group.

Li X. et al, Endocrinology 2011,152 (9): 3312-3322

Bone Anabolic Effects of Scl-Ab are not Blunted by Pre- or Co-treatment with ALN in

OVX Rats

• Weekly treatment with a Scl-Ab resulted insimilar increases in bone formation, bone mass, and bone strength in OVX rats with or without ALN pretreatment.ALN pretreatment.

• Cotreatment of Scl-Ab with ALN demonstratedequivalent efficacy as Scl-Ab alone in OVX rats pretreated with ALN.

Phase I Study of AMG 785, a SclerostinHumanized Monoclonal Antibody

• Phase I, randomized, double-blind, placebo-controll ed, ascending, single-dose study.

• Seventy two healthy subjects received AMG 785 or pl acebo (3:1) subcutaneously (0.1, 0.3, 1, 3, 5, or 10 mg/kg), or IV (1 or 5 mg/kg).

• Subjects were followed for up to 85 days

• Primary objectives: safety and tolerability

• Secondary objectives: pharmacokinetics, bone turnov er markers, and BMD

Phase I Study of AMG 785Adverse Events

Padhi D. et al, J Bone Miner Res 2011, 26 (1): 19-26

Phase I Study of AMG 785Pharmacokinetics

Serum concentration-time profiles of AMG 785.Profiles shown are following a single subcutaneous (s.c.) doseData are mean and SD

Padhi D. et al, J Bone Miner Res 2011, 26 (1): 19-26

Phase I Study of AMG 785Bone Turnover Markers

Mean percent change from baseline on markers of bone turnoverfollowing a single subcutaneous dose of placebo or AMG 785.

P1NP= N-terminal propeptide of type 1 procollagen sCTx= serum C-telopeptide

Padhi D. et al, J Bone Miner Res 2011, 26 (1): 19-26

Phase I Study of AMG 785Bone Mineral Density

Mean percent change from baseline in lumbar spine or total hip BMDfollowing a single subcutaneous dose of placebo or AMG 785

Data are mean and SE.a, p<.05; b p<.01.

Padhi D. et al, J Bone Miner Res 2011, 26 (1): 19-26

Phase I Study of AMG 785

• In this first-in-human clinical study AMG 785 was generally well tolerated.• AMG 785 increased the bone-formation marker P1NP, but not he bone-resorption marker sCTx.• These effects were associated with potentially • These effects were associated with potentially clinically relevant increases in lumbar spine and total hip BMD.• The results support clinical investigation of AMG 785 in human conditions that could benefitfrom an increase in bone formation such as osteoporosis.

Summary I

• Inhibition of sclerostin increases bone formation, mass and strength in animal models of osteoporosis.• These affects are not blunted by pre- or co-treatment with ALN.• A single dose of a sclerostin -neutralizing • A single dose of a sclerostin -neutralizing monoclonal antibody increased bone formation and BMD in humans.• The increase in bone formation is not coupled with an increase in bone resorption, resulting in a larger anabolic window.

Summary II

• Treatments based on inhibition of sclerostin may be a powerful way to restore skeletal bone strength in our patients.

• However, the long -term safety of sclerostin• However, the long -term safety of sclerostininhibition in humans has not been studied.

• At this time, an early phase 2 clinical trial has been completed and at least two large phase 3 studies in postmenopausal women with osteoporosis are about to start.