Antimalarial drug resistance in Africa is an urgent threat to the fight against malaria. To treat malaria, WHO recommends six artemisinin-based combination therapies (ACTs) that combine artemisinin-based compounds with a partner drug. Artemisinin partial resistance has been confirmed for the first time in Africa, specifically in Eritrea, Rwanda, and Uganda, though experts believe that the problem is likely more widespread. Artemisinin partial resistance increases the risk of de novo emergence of partner drug resistance, and importantly, the spread of parasites less sensitive to the partner drugs, which can result in clinical treatment failures. Given the heavy reliance on ACTs in Africa where most cases occur, and the risk resistance poses on our ability to deliver quality case management in the future, the threat of drug resistance must be addressed urgently. The seriousness of this threat has led global partners to mobilize rapidly before resistance leads to major setbacks.
New non-artemisinin-based treatments will not be available before 2026, and the most promising candidate (ganaplacide-lumefantrine) shares a partner drug with artemether-lumefantrine (AL), the most widely used ACT. Until this new drug is available, preserving the efficacy of lumefantrine is therefore a top priority. While ACTs continue to be the mainstay treatment for malaria, short-term resistance mitigation strategies focus on scaling-up and supporting the optimal use of quality ACTs alongside other efforts to mitigate resistance.
Even though multiple quality ACT options are available, the current ACT market is not optimally structured to limit drug pressure and overreliance on a single ACT is potentially driving resistance in Africa. Most African countries rely on AL as their first line treatment, and 30 African countries use AL exclusively. This is despite several countries including other ACTs in their treatment guidelines as possible first line options. As a result, AL’s share of donor-funded ACT procurements is over 80%. With such heavy reliance on AL, artemisinin partial resistance could instigate an emergency and trigger the rapid spread of lumefantrine resistance, causing a rise of cases and deaths, and potentially derailing the most advanced pipeline candidate.
Quickly diversifying ACT markets in countries to reduce drug pressure is a key approach recommended by WHO in their recently published strategy to respond to antimalarial drug resistance in Africa[1]. In the strategy, WHO also calls for research to close evidence gaps on innovative approaches (e.g., multiple first line ACTs) to better use current tools as well as research on how these approaches might address drivers of resistance. Diversifying ACT markets can be achieved through interventions that address supply barriers, create demand for ACTs with limited uptake, and generate evidence on strategies like multiple first-line treatments (MFTs) to mitigate resistance.
Newer ACTs, in particular artesunate-pyronadine (ASPY), offers opportunities to diversify the ACT market. ASPY became available in 2019, but despite having the advantage of once daily dosing, its uptake is low primarily due to its high price (three to four times the AL price), dosing by specific weight bands, and initial but now resolved safety concerns. ASPY’s price is driven by low volumes/poor demand, lack of competition, and high costs of the pyronadine active pharmaceutical ingredient (API). Dihydroartemisinin-piperaquine (DP) also has a reduced pill burden, and its market share has recently grown, however there is only one quality-assured supplier of the child-friendly formulation and prices are also three times that of AL. While it is susceptible to resistance due to the long half-life of piperaquine, close monitoring can ensure early detection and follow-on action.
Supply-side market shaping work is needed to improve the affordability of ASPY and increase suppliers/production capacity. Malaria partners are currently developing market interventions such as a volume guarantee and scoping the need for a co-payment that offsets higher prices. Other interventions being explored by partners include reducing the pyronadine API cost. Generating demand for ASPY is needed to grow the market and decrease prices. This includes early adoption support as well as testing new delivery approaches to close key evidence gaps. This would be complementary to other planned or potential efforts including a volume guarantee, pooled procurement, a co-payment, supporting new ASPY suppliers to enter the market, and technical assistance to countries to develop national policies and MFT treatment strategies.
[1] WHO launched the Strategy to respond to antimalarial drug resistance in Africa on the 18 November 2022 during World Antimicrobial Awareness Week (https://www.who.int/publications/i/item/9789240060265). The strategy proposes that countries, regional bodies and global partners address the threat through four pillars. In Pillar II WHO recommends quickly diversifying ACT markets in countries to reduce drug pressure.