Idenix Pharmaceuticals: Building a Leading Antiviral Franchise Jean-Pierre Sommadossi Chairman and Chief Executive Officer Spring 2006
Safe Harbor This presentation includes forward-looking statements about Idenix and its business, including without limitation, statements regarding drug discovery, research and clinical development, regulatory approval processes and commercialization activities. These forward-looking statements are subject to risks and uncertainties that may cause actual events or results to differ materially from our current expectations. These risks and uncertainties are detailed in our filings with the Securities and Exchange Commission. All forward-looking statements speak only as of the date of this presentation and, except as required by law, we undertake no obligation to update such statements. 2 2
Idenix Building a Leading Antiviral Franchise Mission Products Alliance Global Structure Financial Position Founded in 1998 to discover, develop and commercialize innovative antiviral drugs addressing unmet medical needs in large and growing markets 3 clinical stage drug candidates Novartis global alliance enhances commercial and financial position More than 230 employees at 3 locations in U.S. and Europe Strong balance sheet 3 3
Idenix/Novartis Strategic Alliance Landmark Biotech/Pharma Deal 4 Consummated in May 2003, equity purchase and license agreement Novartis licensed: HBV drug program in May 2003 Valopicitabine (NM283) in March 2006 For licensed programs: Novartis reimburses 100% of development costs on goforward basis from point of license License fees and milestone payments Co-promote and profit split in US and 5 major EU countries First right of refusal to Idenix pipeline Novartis holds 56% of Idenix Maintained equity position through follow-on offering - $81M Standstill until May 2008 2 of 9 board seats 4
Novartis Licensing Terms Hepatitis B Licensed May 2003 $110 million in potential licensing fees and regulatory milestone payments - Upfront licensing payment of $75 million - Upfront to $35 million in regulatory milestones Sales milestones Co-promotion and profit split in U.S. and 5 major EU countries for all licensed products In ROW, payments to Idenix based on product sales Hepatitis C Licensed March 2006 $550 in potential license fees and regulatory milestone payments $25 million milestone received June 2004 Up to $70 million in license fees ($25M paid in March 2006, remainder due upon initiation of phase III trials in US) Up to $455 million in regulatory milestones Sales milestones Co-promotion and profit split in U.S. and 5 major EU countries for all licensed products In ROW, payments to Idenix based on product sales 5 5
Building a Leading Antiviral Franchise NDA Filed for Lead Drug Candidate Indication Program Preclinical Phase Ib/IIa Phase IIb Phase III NDA HBV Telbivudine (LdT) Valtorcitabine (val-ldc) Valopicitabine HCV (NM283) NV-08 HIV NV-05 90% of antiviral nucleosides with successful Phase I/II results have led to NDA approval 1 6 Source: 1 International Antiviral News Vol.7, No.7 and Vol.8 No.1 (01/00) 6
Telbivudine Phase III GLOBE Study Largest Pivotal Hepatitis B Clinical Trial Two-year international phase III head-to-head trial vs. lamivudine Ongoing and fully enrolled with 1,367 patients in intent-to-treat population One-year results completed and being used for worldwide marketing applications Superior to lamivudine on all key virologic endpoints Achieved primary and secondary endpoints US NDA filed by Idenix in 2005 Marketing applications by Novartis submitted in the European Union (EU) and key Asian markets in 1Q2006 7 7
Telbivudine vs Lamivudine in Chinese HBV Patients Significantly Greater Antiviral and Clinical Efficacy vs. Lamivudine Pooled data includes both e-positive and e-negative patients Efficacy at week 52 Number of patients HBV DNA (mean log 10 ) HBV DNA non-detectable by PCR (%) Therapeutic response (%) ALT normalization (%) HBeAg loss (%) HBeAg seroconversion (%) Resistance (%) Telbivudine 167-6.22 HBV DNA <5 log 10 copies/ml with HBeAg loss or ALT normalization HBeAg-positive patients only 70 87 89 31 25 4.5 Lamivudine 165-5.40 43 64 76 20 18 10.1 P value <0.001 <0.001 <0.001 0.003 0.047 8 Hou, J-L. et. al. 2006 HEPA Poster 180 8
Telbivudine vs. Adefovir Phase IIIb Clinical Trial Superior to Adefovir on Primary Efficacy Endpoint: Results at Week 24 HBeAg-positive patients N HBV DNA decrease from baseline (mean log 10 )* HBV DNA <5 log 10 (%) HBV DNA PCR-neg (%) ALT normalized (%) HBeAg loss (%) Telbivudine 44-6.37 95 38.6 61.4 16 Adefovir 89-5.11 58 12.4 62.9 10 * Primary efficacy endpoint percent of patients with HBV DNA level <5 log 10 (AASLD & APASL guideline) COBAS PCR assay limit <300 copies/ml Color designates p<0.01 9 Chan. et. al. 2006 EASL Abstract 9
Telbivudine To Treat Hepatitis B Comprehensive Product Profile Upon Launch Trial Design Status Patients with decompensated cirrhosis (liver failure) Phase III Telbivudine vs. Adefovir Phase IIIb Lamivudine Switch Phase IIIb Lamivudine-resistant patients Phase IIIb 240 patients Two-year study 120 HBeAg-positive patients One-year study 240 HBeAg+ and HBeAg- patients who have received 3-12 months of lamivudine, randomized to continue lamivudine or switch to telbivudine. One-year study 60-120 patients Telbivudine plus adefovir vs. adefovir alone One-year study Over 130 patients enrolled, trial ongoing Full enrolled, ongoing Fully enrolled, ongoing Planned 10 10
11 The US Rx Market for HBV Nucleosides Has Nearly Tripled in the Last 3 Years HBV Weekly Rx Trend 6,000 5,000 2004 growth = 32.7% 4,000 2003 growth = 38.4% 3,000 2,000 1,000 0 Source: IMS Weekly Oral Nucleoside Rx Data through December, 2005. 11 TRx 2005 growth = 30.4% Dec-05 Oct-05 Aug-05 Jun-05 Apr-05 Feb-05 Dec-04 Oct-04 Aug-04 Jun-04 Apr-04 Feb-04 Dec-03 Oct-03 Aug-03 Jun-03 Apr-03 Feb-03 Dec-02 Oct-02 Aug-02
Hepatitis C Current Development Landscape NM283 is Most Advanced Specifically Targeting HCV Replication Candidate Name Target/Type Company Status Nucleoside Polymerase Inhibitors Valopicitabine (NM283) Nucleoside analog R-1626 Nucleoside analog Non-nucleoside Polymerase Inhibitors JTK-003 Non-nucleoside HCV-796 Non-nucleoside Protease Inhibitors VX-950 Protease inhibitor SCH-503034 Protease inhibitor GS-9132/ACH-806 Protease inhibitor Idenix Roche Japan Tobacco/Akros Wyeth/Viropharma Vertex Schering-Plough Gilead/Achillion Phase IIb Phase I Phase I/II Phase Ib Phase II Phase II Phase I HCV therapy should evolve to a combination of oral, small molecules the best from each class of drugs 12 Source: Company Research 12
Chronic HCV Market Innovation Drives More Patients to Be Treated 1000 900 Global HCV Market Sustained Viral Response Rate Pegylated Interferon + RBV SVR: 54% 60% Global Sales ($MM) 800 700 600 500 400 300 200 Interferon 24 Weeks SVR: 12% Interferon 48 Weeks SVR: 20% Interferon + RBV SVR: 41% 50% 40% 30% 20% 10% Sustained Viral Response Rate 100 0 0% Q1 1994 Q1 1995 Q1 1996 Q1 1997 Q1 1998 Q1 1999 Q1 2000 Q1 2001 Q1 2002 Q1 2003 Q1 2004 Q1 2005 S ources: Schering-Plough Quarterly Reports, Hoffman La Roche Quarterly Reports, InterMune Quarterly Reports Credit Suisse First Boston: Hepatitis C Market-Competition Intensifies, March 2003 13 13
Valopicitabine (NM283) Clinical Development Potential First-to-Market Direct HCV Antiviral Drug Treatment-refractory Patients Phase IIb trial - ongoing 190 HCV genotype 1, treatmentrefractory patients enrolled Up to 72 weeks of treatment Due to higher proportion of gastrointestinal side effects at the 800 mg/day dosing level, 800 mg/day dose arms reduced to 400 mg/day 93% of patients from original 178 ITT population will have complete data per previous protocol Treatment-naïve Patients Phase IIb trial - ongoing 174 HCV genotype 1, treatmentnaïve patients enrolled 48-weeks of treatment Due to higher proportion of gastrointestinal side effects at the 800 mg/day dosing level, 800 mg/day dose arms reduced to 200 mg/day or 400 mg/day 88% of patients from original 173 ITT population will have complete data per previous protocol Valopicitabine is an investigational compound for the treatment of hepatitis C that is currently being evaluated in ongoing clinical trials. The most commonly occurring adverse events are gastrointestinal side effects. For most of the patients experiencing gastrointestinal side effects, the side effects (nausea, vomiting, and occasionally diarrhea) are generally mild to moderate, transient, and resolve while remaining on treatment. However, recent data indicate that at the 800 mg/day dosing level, while most patients still report only mild side effects, a higher proportion report moderate or severe intensity to the gastrointestinal side effects compared to observations at the 200 to 400 mg/day dosing level, and may result in treatment discontinuation. 14 14
Valopicitabine Phase IIb Treatment-Naïve Trial Interim Results at Week 12 Demonstrate Convergence of Activity Serum HCV RNA 1 0-1 A B C D E No. of Patients Wk 12 Peg-IFN @D8 + NM283 400-800 mg @D29 30 NM283 200 mg @D1 + Peg-IFN @D8 31 NM283 400-800 mg @D1 + Peg-IFN @D8 31 NM283 800 mg @D1 + Peg-IFN @D8 30 NM283 800 mg @D1 + Peg-IFN @D1 31 (Mean Log 10 Change from Baseline) -2-3 -4-5 0 2 4 6 8 10 12 Weeks B 3.93 log E 3.99 log A 4.27 log C 4.32 log D 4.46 log 15 15
Evidence for Antiviral Synergy: NM283 + pegifn Predicted and Observed Viral Load Reductions, Week 4 200 mg valopicitabine 800 mg valopicitabine peg-ifnα initiated 0 0 Change from Baseline in HCV RNA log10-1 -2-3 -4 NM283 Mono (001) Peg-IFN Mono (006) 283+Peg-IFN (Hyp. Add.) 283+Peg-IFN (Obs 006) Change from Baseline in HCV RNA log10-1 -2-3 -4 Predicted Observed 0 5 10 15 20 25 30 0 5 10 15 20 25 30 Study Day Study Day 16 16
Valopicitabine Phase IIb Treatment-Naïve Trial Convergence of Activity Demonstrated at Weeks 12 and 16 Interim Results Week 12 Results Partial Week 16 Results Group Reduction from Baseline (mean log 10 IU/mL) EVR Rate PCR Negative (20 copies) PCR Negative (600 copies) Reduction from Baseline (mean log 10 IU/mL) PCR Negative (20 copies) PCR Negative (600 copies) A -4.27 87% 60% 70% 4.47 61% 83% B -3.93 87% 45% 71% 4.24 62% 73% C -4.32 94% 48% 77% 4.47 60% 76% D -4.46 90% 67% 77% 4.73 72% 80% E -3.99 81% 52% 65% 4.17 50% 67% Pooled C, D & E -4.26 88% 56% 73% 4.46 61% 74% 17 17
Valopicitabine Phase IIb Study in Treatment- Naïve Patients: Safety Summary GI side effects common with initial dosing, usually mild-moderate; lessen within 1-2 weeks in 70-80% of affected patients, typically manageable with continued treatment 32 of 173 (18%) patients discontinued by Week 12 24 (14%) for adverse events, mostly for GI side effects only 2 patients in 200 mg cohort discontinued 9 SAEs reported through April 1, 2006 3 attributed to NM283 or NM283+pegIFN: dehydration with renal insufficiency and pancreatitis; hyponatremia/hypokalemia; and dehydration with acute gastroenteritis 2 occurred in 800 mg/day arms; 1 in 200 mg/day arm 6 non-attributable: eye infection, flu with dehydration, CHF/diabetes, chest pain, numbness in arm/confusion, burn All patients recovered Grade 3/4 lab abnormalities Most were attributable to peg-ifnα ( WBC, ANC, platelets) 9 patients with Grade 3/4 AST and 2 patients with Grade 3/4 lipase elevation, all in 800 mg treatment groups 18 18
Valopicitabine: Development Plan Within next six months, Idenix will continue to gain additional safety and efficacy data: Ongoing phase IIb clinical trials Valopicitabine/ribavirin drug-drug interaction study to begin in 2Q06 Potential additional dose-ranging data Data from these trials will provide meaningful safety and efficacy data and will further define optimal dosing regimen and phase III development plan Evaluate additional populations: HCV/HIV coinfected patients 19 19
Cash Flow 2005 / 2006 Summary ($ in millions) 9/30/05 Cash Balance, incl. marketable sec. $114.9 4Q 05 Cash Flow Net Proceeds from Follow-On Offering ($18.6) $145.9 12/31/05 Cash Balance, incl. marketable sec. $242.2 1Q 06 Cash Flow Valopicitabine license fee ($22.3) $25.0 3/31/06 Cash Balance, incl. marketable sec. $244.8 Strong Cash Position 20 20
2006 Milestones Expected to Drive Value 21 Telbivudine Global regulatory filings by Novartis 1Q Data from phase IIIb studies Telbivudine vs. adefovir 1H Lamivudine switch 2H 2-year GLOBE study data 2H Anticipated approval US NDA 2H Valopicitabine (NM283) In-licensing decision by Novartis 1Q Phase IIb in treatment-refractory population 24-week data Spring Phase IIb in treatment-naïve population 12-week data Spring 24-week data Fall Initiate ribavirin drug-drug interaction study 1H Pre-clinical File IND for HIV drug candidate 2H 21
Idenix Pharmaceuticals: Building a Leading Antiviral Franchise Investor Contact: Amy Sullivan Executive Director, Corp. Comm. 617-995-9838 investor@idenix.com www.idenix.com