Sotatercept for Rebalancing BMP/TGF- Beta/Activin Signaling in PAH

Sotatercept for rebalancing BMP/TGF- beta/activin signaling in PAH

Paul B. Yu, M.D., Ph.D. Associate Professor of Medicine, Harvard Medical School Physician, Division of Cardiovascular Medicine Brigham and Women’s Hospital Boston, MA Heritable PAH syndromes implicate the BMP9/sBMPR2/ALK1 signaling axis in pulmonary vascular disease Graf et al., BMPRII BMPR2 HPAH TGF TGF BMP BMP Nat Comm 2018 activin ALK1 ACVRL1 HHT2-HPAH BMPRII ALK4 ALK1 ENG ENG HHT1-HPAH TGFBRII ALK5 ALK2 Endoglin ACTRIIA SMAD4 SMAD4 JP-HT ALK7 ALK3 SMAD9 SMAD9 HPAH II I I II BMP9 GDF2 HHT5-HPAH * P P P P P P SMAD2/3 SMAD P P 1/5/9 KCNK3 KCNK3 HPAH P P SMAD2/3 SMAD KCNA5 KCNA5 HPAH 1/5/9 EIF2AK4 EIF2AK4 PVOD/PCH SMAD 4 CAV1 CAV1 HPAH P P SMAD KLF2 KLF2 HPAH SMAD2/3 Nucleus 1/5/9 SMAD4 SMAD4 AQP1 AQP1 HPAH CAGA BRE SOX17 SOX17 HPAH myogenic and vascular homeostasis TBX4 TBX4 HPAH fibrogenic differentiation Is PAH regulated by imbalanced BMP/TGF signaling? BMP2 BMP4 BMP6 BMP7 BMP12 BMP9 BMP10 GDF8 GDF11 activin A activin B activin AC TGFβ1 TGFβ3 TGFβ2

ALK4/5/7 inhibitors SD-208 BMP BMP (Zaiman et al, AJRCCM 2008) IN-1233 BMP9 (Long et al., Circ 2009) Long L et al. SB525334 Nat Med 2015 (Thomas et al., AJP 2009) Lai-Ming Yung, PhD TGFBRII-Fc Yung LM et al, AJRCCM 2016 SMAD 1/5/9 SMAD 2/3 vascular homeostasis myogenic and fibrogenic differentiation What is the contribution of activin/GDF signaling? BMP2 BMP4 BMP6 BMP7 BMP12 BMP9 BMP10 GDF8 GDF11 activin A activin B activin AC TGFβ1 TGFβ3 TGFβ2

ALK4/5/7 inhibitors SD-208 (Zaiman et al, AJRCCM 2008) IN-1233 (Long et al., Circ 2009) SB525334 (Thomas et al., AJP 2009) ALK1-Fc Ivana ACTRIIA-Fc TGFBRII-Fc Nikolic et al. Nikolic, (ACE-011/Sotatercept) Yung LM et al, AJRCCM 2016 MD AJRCCM 2018 SMAD 1/5/9 SMAD 2/3 vascular homeostasis myogenic and fibrogenic differentiation ACTRIIA-Fc attenuates PH progression in SU-Hx rats

ACTRIIA-Fc (1, 3, 10 mg/kg 2x/weekly) Right heart catheterization Non -muscularized SU-Hx (3 weeks) Nx (3 weeks) Fulton’s Index Partially muscularized PV Histology Sprague Completely Muscularized 100 60 Dawley Rat 18.5 31.9 31.2 0.5 42.3 p=0.02 11.8 69.3** 40 0.4 p=0.05 18.8 22.4 50 0.3 27.5 RVSP (mmHg) RVSP 20 0.2 68.0 47.9 45.2 RV/(LV+S) 29.3** 0.1 28.8

(8) (7) (7) (8) (8) (7) (7) (8) Percent of Total Vessels 0 0.0 0 SU-Hx 1 3 10 SU-Hx 1 3 10 SU-Hx 1 3 10

ActRII-Fc (mg/kg twice weekly) ActRII-Fc (mg/kg twice weekly) RAP-011 ACTRIIA(mg/kg twice-Fc weekly) one-way ANOVA dose trend p = 0.03 one-way ANOVA dose trend p = 0.05 (mg/kg twice weekly)

*one-way ANOVA trend p = 0.05 ACTRIIA-Fc attenuates PV remodeling in SU-Hx rats 100

60 SU-Hx 1 mg/kg p=0.05 40

20 (8) (7) (7) (8) % Fully Muscularized Vessels 0 SU-Hx 1 3 10

ActRIIa-Fc (mg/kg twice weekly) one-way ANOVA trend p = 0.05

Pai-1 4 * 3 mg/kg 10 mg/kg 3

mRNA level 1

(Compared to control) 0 vWF

SU-Hx SMA Control 50 µm DAPI SU-Hx + 1mg/kg SU-Hx + 10 mg/kg 7 ACTRIIA-Fc inhibits Activin/GDF8/11-SMAD2/3 signaling and myogenic/fibrogenic differentiation of hPASMC

HPASMC

Control TGFβ1 GDF8 GDF11 Activin A BMP4 8×107 2.5×108 ACTRIIA-Fc - + - + - + - + - + - + **** 8 7 2.0×10 6×10 ** ** p-SMAD1 8 p-SMAD3 1.5×10 *** **** 4×107 1.0×108 Total SMAD1 7 2×10 7 SMA level (RLU) 5.0×10 α Calponin level (RLU) GAPDH 0 0.0 1 1 β β GDF8 Act AAct B GDF8 Act AAct B ControlTGF GDF11 ControlTGF GDF11 Comparison of ACTRIIA-Fc to approved therapies in PH models

Monocrotaline - Prevention SUGEN-Hypoxia - Prevention SUGEN-Hypoxia – Therapeutic

% % Reduction % % Reduction % % Reduction Reduction in RVH Reduction in RVH Reduction in RVH Agent in mPAP RV/(LV+S) Agent in mPAP RV/(LV+S) Agent in RVSP RV/(LV+S)

1 3 5 Bosentan 21 30 Macitentan 36 31 Sildenafil1 10 19

Sildenafil4 24 18 Sildenafil4 22 10 Riociguat1 10 20

5 5 Beraprost NP2 25 28 Beraprost NP2 27 32 Tadalafil + 28 28 Macitentan2 ACTIIA-Fc4 56 47 ACTRIIA-Fc4 51 54 ACTRIIA-Fc3 33 30

1. Clozel etal Exp. Biol and Med (2006) 231: 967-973; Bosentan 300 mg/kg/d 1. Lang et al. PLoS One. 2012;7(8):e43433 2. Akagi et al J Cardiovasc Pharmacol 2016; 67; 290-298; Beraprost NP 150 μg/kg Sildenafil 50 mg/kg/d; Riociguat 10 mg/kg/d 3. Shinohara et al Am J Physiol Lung Cell Mol Physiol 2015; Macitentan 30 mg/kg/d 2 Boucherat et al. Sci Rep. 2017 Jul 3;7(1):4546 4. RAP-011 and Sildenafil (60 mg/kg/d) were tested in same study at CorDynamics Tadalafil 10 mg/kg/d; Macitentan 30 mg/kg/d 5. Right ventricular systolic pressure 3. Current study; 10 mg/kg twice weekly Summary

1. ACTRIIA-Fc (Sotatercept) is a Phase 2 asset tested in nearly 400 patients across 13 trials with excellent tolerability for muscle wasting and anemia 2. ACTRIIA-Fc is a potential mechanism-targeted, non-vasodilator PAH therapy with potent anti-remodeling effects. 3. ACTRIIA-Fc inhibits signaling of activins/GDFs and may augment BMP9; multiple mechanisms of action and cellular targets being considered. 4. PULSAR, a phase 2 study in PAH began enrolling June 2018. Mueller TD FEBS Letters 2012 Mueller TD FEBS Letters 2012 Acknowledgements Yu laboratory – BWH Lai-Ming Yung, PhD Peiran Yang, PhD Ivana Nikolic, MD Geoff Bocobo, BS Lai-Ming Ivana Brian Po-Sheng Megan Zachary Geoff Teresa Po-Sheng Chen, MD Yung, PhD Nikolic, Peiran Chen, MD McNeil, BS Augur, BS Bocobo, Dinter, Zachary Augur, BS MD Yang, PhD BS BS Teresa Dinter, BS Funding Megan McNeil, BS NHLBI R01-HL131910 Luca Troncone, PhD NHLBI R42-HL132742 Acceleron Pharma Boston Biomedical Ravindra Kumar, Ph.D Innovation Center R. Scott Pearsall, Ph.D Fondation Leducq Gang Li, Ph.D. Gilead PAH Scholar Sachindra Joshi, Ph.D. Acceleron Pharma Dianne S. Sako, B.S.