Andre J Marozsan Progenics Pharmaceuticals, Inc.

1. CCR5 Monoclonal Antibody PRO 140 Inhibited HIV-1 Resistant to Maraviroc, a Small Molecule CCR5 Antagonist Andre J Marozsan Progenics Pharmaceuticals, Inc.

2. PRO 140 Background • Humanized CCR5 monoclonal antibody • Broadly and potently inhibits CCR5-mediated HIV-1 entry in vitro • Distinct class of CCR5 inhibitor • Binds extracellular domains vs. transmembrane pocket • Inhibits HIV without blocking the natural activity of CCR5 in vitro • Inhibits HIV via competitive vs. allosteric mechanism • Synergistic with small-molecule CCR5 antagonists • Potential for improved tolerability without drug-drug or drug-food interactions • Potential for infrequent dosing

3. PRO 140 Background (2) • Potent, rapid, prolonged, dose-dependent antiviral activity in HIV-infected individuals • 1.8 log10 mean reduction in HIV RNA following single 5 mg/kg IV dose • >1.0 log10 mean reduction in HIV RNA for 2-3 weeks post-treatment • Individual reductions up to 2.5 log10 • Generally well tolerated • Designated FDA Fast Track drug candidate

4. History of Case C Primary Isolates Conner et al. 1997.J. Exp. Med. 185:621-628. • Subtype B isolate • Patient switched to X4 phenotype • Used as parental virus for AD101, vicriviroc and maraviroc escape studies

5. Generation of Resistance: Methods Culture for generation of resistance: • Infect pooled donor PBMC with CC1.85 virus and culture in the presence and absence of maraviroc. • Begin escape cultures with drug concentration at the IC90. • Passage cultures each week and monitor p24 production. • Double inhibitor concentrations if p24 levels are stable in the culture. • Cultures are considered resistant when viral replication is stable at the highest concentration of drug for two weeks. • Collect viral supernatants after 48 hours of drug-free growth. Generation of HIV-1 envelope clones and testing: • Viral supernatants were analyzed at Monogram Biosciences (South San Francisco, CA) using TrofileTM and PhenosenseTM Entry assays, as well as sequencing of the viral swarm. • Clonal analysis is in progress.

6. Generation of Maraviroc- Resistant Virus Escape culture Isolated at Week 31 Passage controls isolated at Weeks 27 and 36

7. Tropism Analysis Passage Control Virus was R5-tropic at week 27

8. Maraviroc Resistance PhenosenseTM Entry Assay Results CC1.85 CC1.85 Passage Control wk 27 CC1.85 MVC Escape

9. PRO 140 Sensitivity PhenosenseTM Entry Assay Results CC1.85 CC1.85 Passage Control wk 27 CC1.85 MVC Escape

10. Case C 1.85 Sequences V1/V2 - a two amino acid deletion at positions 188-189 was observed in the maraviroc escape virus and in the passage control virus. This deletion was observed in prior Case C escape cultures and was associated with increased CD4 dependence (Pugach et al. Virology. 321:8-22. 2004). V3 Region 300 ^^^ CTRPNNNTRKSIHIGPGRAFYATGDIIGDIRQAHC ......Y......M.....W............... ..................T..S...V......... ..................T..S...V......... R5 CC1.85 Parental Isolate DM CC1.85 Passage Control R5 CC1.85 MVC Escape R5 CC1.85 MVC Escape(Pfizer*) *Westby et al. 2007. J. Virol. 81:2359-2371

11. Summary of Viral Characteristics

12. Summary • A virus resistant to maraviroc was generated in PBMC culture over 31 weeks of passage. • The maraviroc escape virus remained R5; however, the passage control virus became R5X4. • The maraviroc escape virus displayed similar phenotype and sequence to one generated by Pfizer. • For Case C 1/85, maraviroc resistance did not confer cross-resistance to PRO 140.

13. Acknowledgments • Progenics Pharmaceuticals, Inc. • Tom Ketas • William Olson, Ph.D. • Paul Maddon, M.D., Ph.D. • Monogram Biosciences, Inc. • Wei Huang, Ph.D. • Jonathan Toma, Ph.D. • Jeannette Whitcomb, Ph.D. • Chris Petropoulos, Ph.D. This study was supported by Public Health Service award AI066329 from the National Institute of Allergy and Infectious Diseases