title: pfmdr1 amplification is related to increased Plasmodium falciparum in vitro sensitivity to the bisquinoline piperaquine.
abstract: The 4-aminoquinoline bisquinoline piperaquine is an important partner drug in one of the presently recommended artemisinin combination therapies. Recent clinical trials have confirmed its high efficacy in combination with dihydroartemisinin. Resistance to piperaquine alone has, however, been documented. Amplification in copy number of the Plasmodium falciparum multidrug resistance locus on chromosome 5, containing the pfmdr1 gene, has been shown to confer resistance to structurally unrelated antimalarials. Through the determination of the 50% inhibitory concentrations (IC(50)s) and IC(90)s for piperaquine and chloroquine in a set of 46 adapted P. falciparum cultures originating from the Thai-Burmese border, we have characterized the regions around the pfmdr1 gene and identified a significant association between the presence of pfmdr1 duplications and enhanced sensitivity to piperaquine (P = 0.005 for IC(50) and P = 0.002 for IC(90)) and chloroquine, reaching statistical significance at IC(90)s (P = 0.026). These results substantiate the potential importance of pfmdr1 copy number amplifications in the efficacy of the combination therapy piperaquine-dihydroartemisinin. It supports the rational use of 4-aminoquinolines and artemisinin-based compounds, as they independently select for mutually incompatible combinations of mutations.
authors.affiliation: Malaria Research Lab, Department of Medicine, Karolinska Institutet, Stockholm, Sweden. maria.isabel.veiga@gmail.com
authors.forename: M I
authors.initials: MI
authors.lastname: Veiga
authors.forename: P E
authors.initials: PE
authors.lastname: Ferreira
authors.forename: M
authors.initials: M
authors.lastname: Malmberg
authors.forename: L
authors.initials: L
authors.lastname: Jörnhagen
authors.forename: A
authors.initials: A
authors.lastname: Björkman
authors.forename: F
authors.initials: F
authors.lastname: Nosten
authors.forename: J P
authors.initials: JP
authors.lastname: Gil
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000962:Antimalarials / Q000494:pharmacology*; D002738:Chloroquine / Q000494:pharmacology; D018628:Gene Dosage; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D011804:Quinolines / Q000494:pharmacology*; D010879:Piperazines
chemical_list: D018528:ATP-Binding Cassette Transporters; D000962:Antimalarials; D002738:Chloroquine; D015800:Protozoan Proteins; D011804:Quinolines; C059987:mdr gene protein, Plasmodium; C034759:piperaquine; D010879:Piperazines