Clinical and In Vitro Resistance of Plasmodium falciparum to Artesunate-Amodiaquine in Cambodia

Melissa Mairet-Khedim; Rithea Leang; Camille Marmai; Nimol Khim; Saorin Kim; Sopheakvatey Ke; Chhayleang Kauy; Nimol Kloeung; Rotha Eam; Sophy Chy; Brigitte Izac; Denis Mey Bouth; Maria Dorina Bustos; Pascal Ringwald; Frederic Ariey; Benoit Witkowski

doi:10.1093/cid/ciaa628

Clinical and In Vitro Resistance of Plasmodium falciparum to Artesunate-Amodiaquine in Cambodia

Clin Infect Dis. 2021 Aug 2;73(3):406-413. doi: 10.1093/cid/ciaa628.

Authors

Melissa Mairet-Khedim^{1

2

3}, Rithea Leang⁴, Camille Marmai^{5

6}, Nimol Khim^{1

2}, Saorin Kim^{1

2}, Sopheakvatey Ke^{1

2}, Chhayleang Kauy^{1

2}, Nimol Kloeung^{1

2}, Rotha Eam^{1

2}, Sophy Chy^{1

2}, Brigitte Izac^{5

6}, Denis Mey Bouth⁷, Maria Dorina Bustos⁸, Pascal Ringwald⁹, Frederic Ariey^{5

6}, Benoit Witkowski^{1

2}

Affiliations

¹ Malaria Molecular Epidemiology Unit, Institut Pasteur in Cambodia, Phnom Penh, Cambodia.
² Malaria Translational Research Unit, Institut Pasteur, Paris, France.
³ Center for Pathophysiology Toulouse-Purpan (CPTP), INSERM, CNRS, University of Toulouse, Toulouse, France.
⁴ National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia.
⁵ INSERM 1016, Institut Cochin, Université of Paris, Paris, France.
⁶ Service de Parasitologie-Mycologie, Hôpital Cochin, Paris, France.
⁷ World Health Organization, Phnom Penh, Cambodia.
⁸ World Health Organization, Bangkok, Thailand.
⁹ World Health Organization, Geneva, Switzerland.

Abstract

Background: Artesunate-amodiaquine is a potential therapy for uncomplicated malaria in Cambodia.

Methods: Between September 2016 and January 2017, artesunate-amodiaquine efficacy and safety were evaluated in a prospective, open-label, single-arm observational study at health centers in Mondulkiri, Pursat, and Siem Reap Provinces, Cambodia. Adults and children with microscopically confirmed Plasmodium falciparum malaria received oral artesunate-amodiaquine once daily for 3 days plus single-dose primaquine, with follow-up on days 7, 14, 21, and 28. The primary outcome was day-28 polymerase chain reaction (PCR)-adjusted adequate clinical and parasitological response (ACPR). An amodiaquine parasite survival assay (AQSA) was developed and applied to whole genome sequencing results to evaluate potential amodiaquine resistance molecular markers.

Results: In 63 patients, day-28 PCR-adjusted ACPR was 81.0% (95% confidence interval [CI], 68.9-88.7). Day 3 parasite positivity rate was 44.4% (28/63; 95% CI, 31.9-57.5). All 63 isolates had the K13(C580Y) marker for artemisinin resistance; 79.4% (50/63) had Pfpm2 amplification. The AQSA resistance phenotype (≥45% parasite survival) was expressed in 36.5% (23/63) of isolates and was significantly associated with treatment failure (P = .0020). Pfmdr1 mutant haplotypes were N86/184F/D1246, and Pfcrt was CVIET or CVIDT at positions 72-76. Additional Pfcrt mutations were not associated with amodiaquine resistance, but the G353V mutant allele was associated with ACPR compared to Pfmdr1 haplotypes harboring F1068L or S784L/R945P mutations (P = .030 and P = .0004, respectively).

Conclusions: For uncomplicated falciparum malaria in Cambodia, artesunate-amodiaquine had inadequate efficacy owing to amodiaquine-resistant P. falciparum. Amodiaquine resistance was not associated with previously identified molecular markers.

Keywords: Plasmodium falciparum; Cambodia; artemisinin; artesunate-amodiaquine; drug resistance.

Publication types

Research Support, Non-U.S. Gov't
Comment

MeSH terms

Adult
Amodiaquine / pharmacology
Amodiaquine / therapeutic use
Antimalarials* / pharmacology
Antimalarials* / therapeutic use
Artemisinins* / pharmacology
Artemisinins* / therapeutic use
Artesunate / therapeutic use
Asia
Cambodia
Child
Humans
Malaria* / drug therapy
Malaria, Falciparum* / drug therapy
Plasmodium falciparum / genetics
Prospective Studies

Substances

Antimalarials
Artemisinins
Amodiaquine
Artesunate