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Logarithmic Scale

LLOQ

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PPI-461 was well tolerated, clinical and laboratory safety monitoring did not indicate any pattern of clinical adverse events or abnormalities in the tested dosing range of 20-200 mg, with a treatment duration of up to five days

Substantial dose-related systemic exposures were consistently obtained in subjects dosed with PPI-461

Cmax plasma levels achieved quickly in all subjects (1-4 hr), and a consistently long PPI-461 half-life (ca 8-10 hr) resulted in C24 hrlevels exceeding replicon EC50 levels (all genotypes) in all subjects dosed with ≥50 mg

Steady-state concentrations reached within 2 days in 5-day repeat-dose cohort (200 mg QD)

Dosing with a high-fat meal resulted in a 43% reduction in AUC0-24 hr levels in subjects treated with 50 mg PPI-461, C24hr levels were minimally changed

Results support ongoing evaluation of PPI-461 in HCV patients with QD dosing

Safety and Pharmacokinetics of PPI-461, a Potent New HCV NS5A Inhibitor with Pan-Genotype Activity

Purpose: HCV-related mortality is increasing. Most new direct-acting HCV antivirals are optimized for activity vs. HCV genotype-1, comprising <50% of infections globally. PPI-461 is a novel HCV NS5A inhibitor with potent activity vs. all 7 HCV genotypes, g1-7 (R Colonno, EASL 2010). The 50% inhibitory concentrations (EC50s) for PPI-461 are 0.21 nM and 0.01 nM for HCV g1a and g1b, and 0.1 to 9.3 nM for g2a-7a. Here we report the first human trial of PPI-461. Methods: This Phase 1 trial was a randomized, double-blind study of safety and pharmacokinetics (PK) for 5 PPI-461 dosing regimens in healthy volunteers: single doses of 20,50,100 and 200 mg; and a multi-dose regimen, 200 mg QD x 5 days. The dose regimens were tested in sequential groups of 8 subjects (total = 40). In each group subjects were randomized in a 6:2 ratio to blinded treatment with PPI-461 or matching placebo, with 7 day follow-up. The PPI-461 bioanalytic assay had a plasma limit of detection of 10 ng/mL. Results: All PPI-461 dosing regimens were well-tolerated. There were no adverse events (AEs) attributed by the investigator to PPI-461. Non-attributed AEs in the 30 PPI-461 recipients were mild headache (2), moderate backache (1), mild nausea (1), and 2 common colds. AEs in 10 placebo recipients were headache (2) and transient hearing impairment (1). There were no patterns of change or significant abnormalities for any of the safety-related laboratory parameters (hematologic values, serum chemistries, urinalyses and ECGs). PK analyses indicate that systemic uptake of PPI-461 was rapid, with maximal plasma levels (Cmax) reached in 1-4 hr. With single doses of PPI-461 measures of systemic exposure, e.g. Cmax and plasma concentration areas-under-the-curve (AUCs), were dose-proportional. For each group mean Cmax levels far exceeded viral EC50s for HCV g1-7. For the 50 mg or higher dose groups, mean Cmaxlevels exceeded EC50s for HCV g1-7 by 108 to 368,820-fold, depending on HCV genotype and dose, with potentially effective levels in all subjects. A long half-life (ca 8-10 hr across groups) resulted in substantial PPI-461 plasma concentrations 24 hr post-dose (C24 hr). For 50 mg and higher doses, mean C24 hr levels exceeded EC50s for HCV g1-7 by 12 to 65,220-fold, depending on dose and genotype. With the 5-day regimen (200 mg QD)steady-state PK was achieved in 2 days. Conclusions: In this first trial PPI-461 was well-tolerated with all dose regimens. The PK of PPI-461 and its anti-HCV activity in vitro predict a potential for potent pan-genotypic HCV inhibition with low once-daily doses (50-200 mg), facilitating co-formulation with other HCV antivirals in future combination therapies for hepatitis C.

Introduction

Single-Dose PK ResultsImproved Potency and Lead

Multiple-Dose PK Results (200 mg x 5)Phase 1a Trial (Volunteers) Summary

Safety Profile: All Adverse Events

LB-1261st Annual Mtg of the American Association for the Study of the Liver Diseases, Boston, MA, USA

Steady State (Cmin) achieved following second dose No evidence of accumulation after third dose

Abstract Study Design and Population

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In fasted subjects, Cmax values ranged from a low of 158 ng/mL (213 nM) following a 20 mg dose to a maximum of 4,538 ng/mL (6,144 nM) following a 200 mg dose

Effect of High Fat Meal

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Cohort PPI-461Dose Oral Regimen Randomization

(PPI-461:Placebo)

A 20 mg Single dose 6:2

B 50 mg Single dose 6:2B (Fed)* 50 mg Single dose 6:2

C 100 mg Single dose 6:2

D 200 mg Single dose 6:2

E 200 mg Once daily for 5 days 6:2*Received second 50 mg dose after standardized high-fat meal

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Consistent oral bioavailability and substantial 24 hr systemic exposures observed

Maximal plasma concentrations (Cmax) achieved quickly (1-4 hr), were dose-dependent and exceeded the EC50s of all HCV genotypes by orders of magnitude

Plasma levels at 24 hr (C24 hr) post-dosing substantially exceeded replicon EC50 levels for all HCV genotypes

Linear Scale

Parameter (unit) Treatment Subjects* Mean (SD) Min / Median / Max

Age (years)

PPI-461 30 32.6 (9.6) 20.2 / 30.2 / 61.1Placebo 10 33.8 (9.2) 23.8 / 30.6 / 50.4

Weight (kg)

PPI-461 30 80.6 (11.1) 61.9 / 78.2 / 106Placebo 10 84.8 (9.4) 71.0 / 85.5 / 103

BMI (kg/m2)

PPI-461 30 25.6 (3.0) 20.0 / 25.5 / 31.3Placebo 10 26.5 (2.1) 23.2 / 27.2 / 29.0

Cohort(Dose)

Cmax (ng/mL) T½ (hr) AUC24 hr (hr*ng/mL)

Mean Range Mean Range Mean RangeA

(20 mg) 342 158-598 7.9 4.7-9.2 2,227 908-3,657

B(50 mg) 749 443-986 10.3 6.3-15.1 7,186 3,222-9,778

B – Fed(50 mg) 317 113-513 9.4 6.7-10.9 4,240 1,396-6,804

C(100 mg) 1,336 907-2,064 7.6 5.4-9.0 13,782 8,312-21,454

D(200 mg) 2,732 2,152-3,990 9.9 7.9-14.4 33,649 27,904-40,384

E – Day 0(200 mg) 2,531 1,642-3,362 7.0 4.7-8.1 22,204 12,071-30,691

E – Day 4 (200 mg) 2,878 1,784-4,538 7.9 5.9-9.5 29,797 14,432-47,064

PK Parameters for Cohorts A-E

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Administration of 50 mg of PPI-461 within 30 min after a high-fat meal resulted in a 43% mean decrease in AUC0-24 hr values, but minimal change in the C24 hr levels

Cmax and C24 hr with fed dose still exceeded EC50 of all HCV genotypes

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Active 20 mg Backache Moderate No Resolved

Active 50 mg Common Cold Mild No Resolved Pre & post

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Headache Mild No Resolved Same subject as ‘cold’

Active 100 mg Nausea Mild No Resolved

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Active 200 mg(5 Days) Headache Mild No Resolved Several in

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Headache Mild Possibly Resolved Both in same subject

Dose 1 Dose 2 Dose 3 Dose 4 Dose 5

Objectives

HCV-related severe morbidity and mortality projected to increase 2 to 4-fold Potential treatment advances offered by current HCV PIs focused on HCV genotype-1

infection, comprising less than half of patients globally PPI-461 is a highly potent & selective NS5A inhibitor with pan-genotypic HCV activity

in replicon assays (EC50s of 0.2 nM [1a], 0.01 nM [1b], 0.1 - 9.3 nM [2a-7a]) Combination studies in HCV replicon cell assays showed additive to synergistic

activity with other classes of HCV inhibitors, with no evidence for antagonism No cross-resistance between PPI-461 and other classes of HCV inhibitors PPI-461 was well-tolerated in a battery of preclinical toxicology studies

Safety and tolerability of four single oral doses (20, 50, 100, and 200 mg) of PPI-461 taken after an overnight fast

Pharmacokinetics (PK) of PPI-461 after each single dose Preliminary food effect sub-study: Compare PK profile for fasted vs. fed doses Safety/tolerability and PK for highest well-tolerated dose administered once daily for

5 days

Subjects were healthy volunteers ages 18-65 with a BMI of 18-32 kg/m2 and able to give informed consent

Both males and females were eligible (females of non-child bearing capacity only), however, no eligible female subjects were identified for this study

Five sequential study cohorts (8 subjects/cohort, total study subjects = 40) Cohorts A-D received single oral dose of PPI-461 (20, 50, 100 or 200 mg) or placebo,

and cohort E received 5 days of consecutive dosing at the highest tested dose (200 mg), after an overnight fast

Eight subjects/cohort were randomized to active PPI-461 or placebo (6:2 ratio) Double-blind: subjects and clinical site personnel blinded to randomized treatment Study advancement to each higher dosing level contingent on satisfactory safety

observations for previous cohort(s) Preliminary food effect sub-study: 50 mg dose administered in same subjects, once

after overnight fast and again after washout and high fat meal Dosage form: Powder in a capsule

Assessments Safety-related observations included vital signs, physical exams, clinical adverse

events (AEs), serial ECGs, and safety-related laboratory assessments: complete blood counts with leukocyte differentials, full clinical chemistry panels, coagulation (PT & aPTT) and urinalyses

Intensive plasma sampling for PK after each single-dose exposure (cohorts A-D) Intensive plasma sampling for PK after 1st and last (5th) doses, for cohort E; pre-dose

‘trough’ PK sampling prior to 2nd, 3rd, 4th, and 5th doses Study conducted with applicable approvals from the U.K. MHRA and the local Ethics

Committee

All subjects completed the study satisfactorily, no premature discontinuations All dosing regimens were well-tolerated

− No serious or severe AEs, no pattern of adverse events of any type− No persistent or clinically significant abnormalities in safety-related laboratory parameters

or ECGs No AEs attributed to PPI-461 by investigator, 2 attributed to placebo All adverse events resolved spontaneously

Nathaniel Brown1, Pamela Vig1, Eric Ruby1, Anna Muchnik1, Elana Pottorff1, Steven Knox2, Salvatore Febbraro3, Bill Wargin4, Tine Molvadgaard5, Andrew Jones3, Leping Li1 & Richard Colonno1

1Presidio Pharmaceuticals, San Francisco, CA, USA, 2Smerud Medical Research International, Oslo, Norway, 3Simbec Research Ltd, Merthyr Tydfil, UK, 4PK-PM Associates, Chapel Hill, NC, USA, 5Smerud Medical Research Denmark, Brondby, Denmark.

*All subjects were male

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Steady-StateAchieved

Demographics & Baseline Clinical Features