Malaria is a major global health threat of which approximately 40% of the world s population is at risk. Approximately 1-2 million deaths can be attributed to malaria every year with an additional 300 million acute illnesses annually. Although several pharmacophores have been developed to combat malaria, quinolines are by far the most prevalent because they are chemically stable and relatively inexpensive to manufacture on a large scale, making them particularly useful for distribution in developing countries. Because of the widespread resistance to these agents, there is a pressing need to develop new antimalarial drugs against novel cellular targets within the P. falciparum parasite. Chloroquine (CQ) resistance is caused, in part, by its transport out of the digestive vacuole allowing the organism to live and propagate in the presence of high doses of the drug. The Plasmodium falciparum Chloroquine Resistance Transporter (PfCRT) has therefore been identified as attractive drug target for inhibition as well as to restore sensitivity to CQ-type drugs. The goal of this consortium is to focus on this enzyme and its mutant forms, since the wild-type protein is an essential gene product in its own right for parasite development, and because improved agents against the CQtransporting mutants would make dual therapy more effective in combination with other anti-malarial drugs. We will use a comprehensive and highly innovative strategy, encompassing high-throughput screening, drug design, in vitro and in vivo assays, medicinal chemistry, and pre-clinical testing of novel therapeutics to specifically target the essential protein PfCRT in the P. falciparum malaria parasite. We will be combining state-of-the-art chemistry design, malarial functional analysis, and high-resolution structure determination/design to discover new PfCRT inhibitors and determine their mechanisms of action, testing them also for drug metabolism/phamacokinetics. The synergy of the techniques and the combined experience of the investigators promises an exciting and effective drug development program designed to rapidly create, test, and refine novel antimalarial drugs to fight the world s largest killer.
Our specific aims are to (1) expand the structural space for inhibitors of PfCRT, (2) optimize antimalarial activity of new agents against wild-type and chloroquine-transporting mutants of PfCRT, and (3) conduct preclinical evaluation and optimization of our PfCRT inhibitors.

Public Health Relevance

Malaria and its drug resistance is a major health problem causing 1-2 million deaths worldwide. A major cause of chloroquine resistance is transport of the drug by the Plasmodium falciparum Chloroquine Resistance Transporter (PfCRT), which plays an essential role in the normal life cycle of the parasite. The goal of this consortium is to use a highly innovative and synergistic strategy to inhibit this enzyme thereby circumventing chloroquine resistance and also killing the parasite.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
High Priority, Short Term Project Award (R56)
Project #
1R56AI090832-01
Application #
8084905
Study Section
Special Emphasis Panel (ZAI1-LR-M (M1))
Program Officer
Rogers, Martin J
Project Start
2010-06-21
Project End
2012-05-31
Budget Start
2010-06-21
Budget End
2012-05-31
Support Year
1
Fiscal Year
2010
Total Cost
$1,023,775
Indirect Cost
Name
Scripps Research Institute
Department
Type
DUNS #
781613492
City
La Jolla
State
CA
Country
United States
Zip Code
92037
Callaghan, Paul S; Siriwardana, Amila; Hassett, Matthew R et al. (2016) Plasmodium falciparum chloroquine resistance transporter (PfCRT) isoforms PH1 and PH2 perturb vacuolar physiology. Malar J 15:186
Callaghan, Paul S; Hassett, Matthew R; Roepe, Paul D (2015) Functional Comparison of 45 Naturally Occurring Isoforms of the Plasmodium falciparum Chloroquine Resistance Transporter (PfCRT). Biochemistry 54:5083-94
Baro, Nicholas K; Callaghan, Paul S; Roepe, Paul D (2013) Function of resistance conferring Plasmodium falciparum chloroquine resistance transporter isoforms. Biochemistry 52:4242-9
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Baro, Nicholas K; Pooput, Chaya; Roepe, Paul D (2011) Analysis of chloroquine resistance transporter (CRT) isoforms and orthologues in S. cerevisiae yeast. Biochemistry 50:6701-10