| Drug Class | Developer | Compound | Stage |
| HCV NS3 serine protease inhibitors | Boehringer Ingelheim | BILN 2061 | Completed phase I; planned phase II on hold pending investigation of toxicities in animals |
| Vertex | VX-950 | Phase I to begin in 2004 |
| Schering-Plough | SCH7 | Phase I |
| HCV NS5B RNA-dependent RNA polymerase inhibitors | Idenix | NM283 | Phase II in combination with pegylated interferon to begin in 2004 |
| Japan Tobacco | JTK-003 | Phase II |
| Japan Tobacco | JTK-109 | Phase I |
| Rigel | R803 | Phase I/II |
| Roche | R1479 | Phase I |
| ViroPharma | HCV-086 | Phase I |
| Imino sugar derivatives | Micrologix | MBI-2353 (celgosivir) | Phase II to begin in 2004 |
| United Theraputics | UT231B | Phase II |
| Monoclonal antibodies | XTL | HepeX-C | Phase II |
| Antisense oligonucleotides | Isis | ISIS-14803 | Phase I/II in combination with pegylated interferon and ribavirin |
| Interferon variants and alternates | InterMune | Infergen (interferon alfacon-1; consensus interferon) | Phase III study in combination with ribavirin initiated in 2004 |
| InterMune | pegylated Infergen | Phase I conducted in 2003, further development on hold for financial reasons |
| Human Genome Sciences | Albuferon-alpha | Phase II dose-ranging study underway |
| BioMedicines | omega interferon | Phase II underway |
| InterMune | interferon gamma-1b (Actimmune) | Phase II study in combination with Infergen initiated in 2004 |
| Next-generation ribavirin | Valeant | Viramidine (ribavirin prodrug) | Phase III studies in combination with pegylated interferon |
| Vertex | Merimepodib (Vertex 497, an IMPDH inhibitor) | Phase IIb study in combination with pegylated interferon and ribavirin to begin in 20004 |
| Other immunomodulators, broad antivirals, and non-specific therapies | SciClone | Zadaxin (thymosin alfa-1; thymlfasin) | Two phase III studies in combination with pegylated interferon; another phase III study in combination with pegylated interferon and ribavirin to begin in 2004 |
| Maxim | Ceplene (histamine dihydrochloride) | Phase II study with pegylated interferon and ribavirin; phase Ia study of oral formulation completed |
| Anadys | isatoribine (ANA 245, a TLR7 agonist) | Phase I; ANA 971 (an oral prodrug of isatoribine) entered phased I in 2004 |
| Coley | Actilon (CPG 10101, a TLR9 agonist) | Phase I/II underway; phase II to begin in 2004 |
| Kemin Pharma | KPE02003002 | Phase II |
| Idun | IDN-6556 (apoptosis inhibitor) | Phase II planned |
| Vaccines | Innogenetics | therapeutic vaccine | Phase II |
| Intercell | therapeutic vaccine | Phase II |
| Chiron | therapeutic vaccine | Phase I |
| Chiron | preventative vaccine | Phase I |
Overview of the Drug Development Process