WWARN Study Groups: our latest findings

Artemisinin-based combination therapies (ACTs) are very effective antimalarial drugs and have contributed substantially, along with other intervention strategies such as bed nets, to the dramatic decrease in malaria related sickness and deaths over the past decade. However, artemisinin resistance has emerged in many parts of Southeast Asia, and poses a serious threat to malaria control and elimination efforts.

There are currently no suitable alternatives to the ACTs antimalarials that are widely used in Asia and Africa. Therefore, optimising how we treat patients with existing ACTs to ensure they are as efficacious as possible could help to delay the emergence or spread of resistance in regions where resistance has been or will be imminently identified.

The WWARN Network has initiated a series of pooled analyses of individual patient data to assess the risk factors associated with recurring malaria infection after treatment with the three main ACTs; artemether-lumefantrine (AL), artesunate-amodiaquine (ASAQ) and dihydroartemisinin-piperaquine (DP). Our Dose Impact Study Groups explore the impact of different dosing regimens on the clinical efficacy and the variability of the mg / kg dosing of antimalarials administered during routine hospital visits.

A very large sample size for each medication has given us improved statistical and analytical power to look more closely at sub- groups among the patients (like small children) who are especially vulnerable to failing antimalarial treatment, even when they are given as prescribed. 

The first of these pooled analyses, published in Plos Medicine, confirms that young patients treated with dihydroartemisinin-piperaquine received too low a dose and the rates at which patients were cured were significantly lower in under-dosed patients. Our second Study Group, published in Lancet Infectious Diseases, found that young malnourished children treated with artemether-lumefantrine in Africa do not respond to the treatment as well as patients who are not malnourished. Moreover, young patients in Asia, who received a low dose of AL, also had a higher risk of not being cured.

These two examples show the importance of sharing data to identify the factors that affect the efficacy of ACTs. The third dose impact pooled analyses - the ASAQ Dose Impact Study Group - is currently under review for publication later this month.  Other analyses will begin soon, including the ASMQ Artesunate-Mefloquine (ASMQ) Dose Impact Study Group.

Our research focuses on a diverse range of areas; we combine expertise from different countries and institutions to explore interesting questions that aim to improve the efficaciousness of antimalarial medicines and malaria treatment approaches.

Other Study Groups include:

• The ACT Africa Baseline Study Group is examining the early parasite response in patients treated with ACTs in Africa
• The Gametocyte Carriage Study Group is assessing the risk factors associated with gametocyte presence and gametocyte carriage duration
• The Haematology Study Group is in the first phase of analysis

“These Study Groups highlight how researchers from around the world can come together and pool their data to benefit the whole malaria research community,” says Professor Ric Price, Head of the WWARN Clinical Scientific Group.  “The power of such a collaborative research approach is already helping to support the optimisation of current antimalarial treatments, to reduce the likely spread of antimalarial drug resistance, and ultimately these results should help to save more lives.”

We actively support data sharing between members in our Network. Recently Professor Francois Nosten, from the Shoklo Malaria Research Unit in Thailand, shared data from one of his clinical trials on this website, making it accessible to anyone who would like to reanalyse the results. 

We welcome your ideas for new Study Groups, please email us with your questions info@wwarn.org. This update was written by Dr Christian Nsanzabana, WWARN Scientific Coordinator.