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New Drugs for Protozoan Parasites. Wesley C. Van Voorhis, MD PhD Professor of Medicine University of Washington. New Drugs for Protozoan Parasites. The problem What we are doing What you can do. Malaria African Sleeping Sickness. Leishmaniasis Chagas’ Disease.
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New Drugs for Protozoan Parasites Wesley C. Van Voorhis, MD PhD Professor of Medicine University of Washington
New Drugs for Protozoan Parasites • The problem • What we are doing • What you can do
Malaria African Sleeping Sickness Leishmaniasis Chagas’ Disease New Drugs for Protozoan Parasites
Malaria WHO/TDR
African Sleeping Sickness(African Trypanosomiasis)Trypanosoma bruceigambiense infection
Leishmaniasis Cutaneous Leishmaniasis Visceral Leishmaniasis
Chagas’ Disease Acute infection: Romaña’s sign Chagasic Megacolon (Barium enema) Chagasic Megacardia Trypanosoma cruzi
New Drugs Needed • Effective vaccines unavailable • Drugs often toxic • Resistance mounting
U of WA Protozoan Drug Discovery • X-Ray Crystallography • Wim Hol Group • Chemistry • Mike Gelb Group • Parasitology • Wes Van Voorhis and Fred Buckner Groups
Protein Farnesyltransferase Inhibitors (FTI) • Anti-cancer drug development • >30 drug companies investigating • FTI toxic to protozoans • “Piggy-back” approach
Protein Farnesylation Protein Farnesyl- transferase
T. brucei + FTI Farnesyl-O-NH-PA ester
BMS-214662 FTI T. brucei ED50 200 nM
BMS FTI vs. T.brucei rhod. in mice Mice infected on day 0, dosed at 600 mg/kg/day by oral gavage days 0-7
FTI • Promising results with T. brucei • 30 nM inhibitor of Malaria growth • Investigating T. cruzi and Leishmania
Now, the Hard Part • Pharmacokinetics • Toxicity • Large animal trials • Phase I, II, III trials
New Paradigm for Drug Development • Non-profit Drug Company • Private/Govt. Funded • 100s of Scientists • Chemistry • Pharmacokinetics • Toxicology • Phase I, II, III
What Can You Do? • Develop New Drugs for Parasites • Lab investigation • Field trials • Policy development • Get Drugs to Developing Countries • Personal involvement • MSF • Policy development
Malaria • 300-500 million cases/yr • 2 million deaths/yr • mostly < 5 y.o. children • Transmitted by Anopheles mosquitoes • Drug resistance widespread • Vaccines problematic
African Trypanosomiasis • At risk: 60 million people, 36 countries • 300,000 - 500,000 infected • T. brucei • transmitted by tse tse fly • Toxic drug therapy • Resistance to drugs widespread • Little hope for vaccines • antigenic variation
Leishmaniasis • At risk: 350 million people, 88 countries • 12 million people infected • Annual Incidence: 2 million • Transmitted by sandflies • Drugs toxic • Drug resistance mounting • Vaccines not available Leishmania in a macrophage Sandfly
Chagas’ Disease • American trypanosomiasis • Trypanosoma cruzi • Transmitted by reduviid bugs • Drugs toxic • Resistance documented • Vaccine not available