1. The Discovery and Clinical Evaluation of the Cyclophilin Inhibitor SCY-635 in HCV Infected Subjects Michael Peel1, Richard Harris1, Zhuhui Huang2, Sam Hopkins1, Keqiang Li1, Thomas E. Richardson1, Bernard Scorneaux1, Andrew Scribner1, Steve Wring1.1SCYNEXIS INC. and 2Southern Research Institute. HCV2009.
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2. Non-immunosuppressive Cyclosporins Hepatitis-C
Cyclosporin A (IC50)
CypA 10 ng/mL
CypB 12 ng/mL
HCV EC50 ~ 0.3 uM
IL-2 inh ug/mL
NIM-811 (IC50)
CypA 10 ng/mL
CypB 25 ng/mL
HCV EC uM
IL-2 inh. >10 ug/mL
Debio-025 (IC50)
CypA 14 ng/mL
CypB 10 ng/mL
HCV EC uM
IL-2 inh. 2.5 ug/mL
Watanabe (2004); Bartenschlager (2006); Tang (2008)
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3. Designing non-immunosuppressive Cyclosporins
Cyclosporin:Cyclophilin A complex
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4. 4-(g-OH-Leu) Analogs have HCV Activity and Decreased Immunosuppressive Potential
CypA 14 ng/mL
CypB 20 ng/mL
HCV EC50 ~ 0.35 uM
IL-2 inh ug/mL
CypA/B 11/30 ng/mL
HCV EC50 ~ 0.1 uM
IL-2 inh ug/mL
CypA/B 8/5 ng/mL
HCV EC50 ~ 0.07 uM
IL-2 inh. 0.1 ug/mL
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5. Non-immunosuppressive 4-(g-OH-Leu)-3-Sar-Thioethers with Potent HCV Activity
SCY-635
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6. SCY-635 Inhibits Cyclophilin A PPIase Catalytic Activity
Cyclosporin A
Ki = 1.84 ± 0.33 nM
Ki = 2.64 ± 0.56 nM
Cyclophilin:Protease coupled assay using N-Suc-Ala-Ala-Pro-Phe-p-nitroanilide.
G. Fischer, Max-Planck
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7. SCY-635 Binds to the Cyclophilin Active Site
Key residues required for PPiase activity are blocked by ligand
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8. Effect of Serum on Anti-Viral Activity in the Replicon Assay
SCY-635 is ca. 77% protein bound (cf. >99% for CsA)
Human serum added to subgenomic replicon system. EC50s determined at 0%
10%, 20%, 40% are 0.08 uM, 0.09 uM, 0.11 uM and 0.12 uM respectively.
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9. Synthesis of Cyclosporin Derivatives
Biotransformation of Cyclosporin
Chemical modification of Cyclosporins
X = H or OH
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10. SCY-635 Profile
SCY-635
Potent inhibitor of HCV RNA replication in con 1b derived replicons; EC50 = 0.1 uM (subgenomic); EC50 = 0.17 uM (full length)
Additive or synergistic activity with IFNa, ribavirin, protease, polymerase. (Data to be presented at AASLD 2009, S. Hopkins)
No inhibition (IC50 >10 uM) of Cyp450 3A4, 2D6, 2C9, 2C19.
No induction of Cyps in primary human hepatocytes.
Weak interaction with Pgp transporter (cf. CsA)
Low intrinsic clearance rates in microsomal preparations.
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11. SCY-635 Profile Orally bioavailable in multiple animal species.
Rat: Cl = 110 mL/h/kg; t0.5 = 24 h; F = 22%.
Monkey: Cl = 45 mL/h/kg; t0.5 = 32 h; F = 13%.
Improved oral exposure compared to CsA, Debio-025 from simple vehicle.
Mouse blood concentrations: Oral delivery (8 mpk) of CsA, Debio-025 and SCY-635
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12. Clinical Studies
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13. Clinical Proof of Principle Study Design
15-day randomized, double blind assessment of safety, pharmacokinetics, and effect of treatment on plasma viremia.
Entry criteria
Proof of Principle Study was conducted in two parts:
Subjects remained in the CRU on Study Days 1, 2, 3, 4, and 14 for intensive PK and viral load sampling.
Adults aged 18 to 65
No co-infections
Genotype 1 infection
Plasma viral > 100,000 IU/mL
Enrollment in Cohort 6 restricted to treatment naïve subjects
Cohorts 1-3
(9 active: 3 placebo)
Cohorts 4-6
(6 active: 1 placebo)
Cohort 1: 30 mg q.d.
Cohort 4: 100 mg t.i.d.
Cohort 2:100 mg q.d.
Cohort 5: 200 mg t.i.d.
Cohort 3: 300 mg q.d.
Cohort 6: 300 mg t.i.d.
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14. Safety Summary No deaths or serious adverse events occurred.
No subjects discontinued treatment.
One Grade 4 laboratory event (elevated triglycerides following consumption of a high fat meal); resolved without interrupting treatment.
One subject missed one dose of study medication due to transient nausea on Day 3.
All other treatment-related adverse events resolved without interruption of study medication.
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15. SCY-635-104: Mean and Median HCV RNA Profiles for Cohort 6 vs
SCY : Mean and Median HCV RNA Profiles for Cohort 6 vs. Pooled Placebo
Change in HCV RNA for subjects treated with SCY-635 was significant (p<0.05) from Study Days 2 through 15 (Student’s t-test; one-tailed, unequal variance)
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16. Summary
Thioether derivatives of [4-hydroxy-Leu]4-cyclosporin A have potent activity in the HCV replicon assay and have low immunosuppressive potential.
SCY-635 is a potent inhibitor of the enzymatic activity of Cyclophilin A.
The potency of SCY-635 in the replicon system is unaffected by the addition of added serum.
SCY-635 achieved a mean 2.3 Log(10) reduction of plasma viral RNA when delivered to treatment naïve HCV patients at a dose of 300 mg t.i.d.
No clinical or laboratory evidence of dose limiting toxicities was observed.
SCY-635 is a new cyclophilin inhibitor that has robust anti-HCV activity as a single agent and further, dose escalating, clinical studies are planned.
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17. Contributors Chemistry Clinical Biochemistry SCYNEXIS DMPK
Keqiang Li
Andrew Scribner
Biochemistry
Richard Harris
Bernard Scorneaux
Mari Vogel
Sarah Moser
DMPK
Steve Wring
Ryan Randolph
Craig Smittley
Clinical
Sam Hopkins (CSO)
Pam Rusnak
Betty DeMassimo
SCYNEXIS
Yves Ribeill (CEO)
Collaborators
Zhuhui Huang (SRI)
Gunther Fischer (Max-Planck)
Hengming Ke (UNC)
Doug Heuman, M.D. (Maguire MC)
Edith Gavis, R.N. (Maguire MC)
Jay Lalezari (Quest)
Eileen Glutzer, R.N. (Quest)
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