The effect of dosing strategies on the therapeutic efficacy of artesunate-amodiaquine for uncomplicated malaria: a meta-analysis of individual patient data

Post-kala-azar dermal leishmaniasis (PKDL) drug efficacy study landscape: A systematic scoping review of clinical trials and observational studies to assess the feasibility of establishing an individual participant-level data (IPD) platform

BACKGROUND

Post-kala-azar dermal leishmaniasis (PKDL) is a dermatosis which can occur after successful treatment of visceral leishmaniasis (VL) and is a public health problem in VL endemic areas. We conducted a systematic scoping review to assess the characteristics of published PKDL clinical studies, understand the scope of research and explore the feasibility and value of developing a PKDL individual patient data (IPD) platform.

METHODS

A systematic review of published literature was conducted to identify PKDL clinical studies by searching the following databases: PubMed, Scopus, Ovid Embase, Web of Science Core Collection, WHO Global Index Medicus, PASCAL, Clinicaltrials.gov, Ovid Global Health, Cochrane Database and CENTRAL, and the WHO International Clinical Trials Registry Platform. Only prospective studies in humans with PKDL diagnosis, treatment, and follow-up measurements between January 1973 and March 2023 were included. Extracted data includes variables on patient characteristics, treatment regimens, diagnostic methods, geographical locations, efficacy endpoints, adverse events and statistical methodology.

RESULTS

A total of 3,418 records were screened, of which 56 unique studies (n = 2,486 patients) were included in this review. Out of the 56 studies, 36 (64.3%) were from India (1983-2022), 12 (21.4%) from Sudan (1992-2021), 6 (10.7%) were from Bangladesh (1991-2019), and 2 (3.6%) from Nepal (2001-2007). Five (8.9%) studies were published between 1981-1990 (n = 193 patients), 10 (17.9%) between 1991-2000 (n = 230 patients), 10 (17.9%) between 2001-2010 (n = 198 patients), and 31 (55.4%) from 2011 onwards (n = 1,865 patients). Eight (14.3%) were randomised clinical trials, and 48 (85.7%) were non-randomised studies. The median post-treatment follow-up duration was 365 days (range: 90-540 days) in 8 RCTs and 360 days (range: 28-2,373 days) in 48 non-randomised studies. Disease diagnosis was based on clinical criterion in 3 (5.4%) studies, a mixture of clinical and parasitological methods in 47 (83.9%) and was unclear in 6 (10.7%) studies. Major drugs used for treatment were miltefosine (n = 636 patients), liposomal amphotericin B (L-AmB) (n = 508 patients), and antinomy regimens (n = 454 patients). Ten other drug regimens were tested in 270 patients with less than 60 patients per regimen.

CONCLUSIONS

Our review identified studies with very limited sample size for the three major drugs (miltefosine, L-AmB, and pentavalent antimony), while the number of patients combined across studies suggest that the IPD platform would be valuable. With the support of relevant stakeholders, the global PKDL community and sufficient financing, a PKDL IPD platform can be realised. This will allow for exploration of different aspects of treatment safety and efficacy, which can potentially guide future healthcare decisions and clinical practices.

Does acute malnutrition in young children increase the risk of treatment failure following artemisinin-based combination therapy? A WWARN individual patient data meta-analysis

BACKGROUND

The geographical, demographic, and socioeconomic distributions of malaria and malnutrition largely overlap. It remains unknown whether malnutrition affects the efficacy of WHO-recommended artemisinin-based combination therapies (ACTs). A previous systematic review was inconclusive as data were sparse and heterogeneous, indicating that other methodological approaches, such as individual patient data meta-analysis, should be considered. The objective of this study was to conduct such a meta-analysis to assess the effect of malnutrition (wasting and stunting) on treatment outcomes in children younger than 5 years treated with an ACT for uncomplicated falciparum malaria.

METHODS

We conducted a meta-analysis of individual patient data from studies identified through a systematic review of literature published between 1980 and 2018 in PubMed, Global Health, and Cochrane Libraries (PROSPERO CRD42017056934) and inspection of the WorldWide Antimalarial Resistance Network (WWARN) repository for ACT efficacy studies, including children younger than 5 years with uncomplicated falciparum malaria. The association of either acute (wasting) or chronic (stunting) malnutrition with day 42 PCR-adjusted risk of recrudescence (ie, return of the same infection) or reinfection after therapy was investigated using Cox regression, and with day 2 parasite positivity using logistic regression.

FINDINGS

Data were included from all 36 studies targeted, 31 from Africa. Of 11 301 eligible children in 75 study sites, 11·5% were wasted (weight-for-height Z score [WHZ] <-2), and 31·8% were stunted (height-for-age Z score [HAZ] <-2). Decrease in WHZ was associated with increased risk of day 2 positivity (adjusted odds ratio 1·12, 95% CI 1·05-1·18 per unit; p=0·0002), treatment failure (adjusted hazard ratio [AHR] 1·14, 95% CI 1·02-1·26, p=0·016), and reinfection after therapy (AHR 1·09, 1·04-1·13, p=0·0003). Children with milder wasting (WHZ -2 to -1) also had a higher risk of recrudescence (AHR 1·85, 1·29-2·65, p=0·0008 vs WHZ ≥0). Stunting was not associated with reduced ACT efficacy.

INTERPRETATION

Children younger than 5 years with acute malnutrition and presenting with uncomplicated falciparum malaria were at higher risk of delayed parasite clearance, ACT treatment failure, and reinfections. Stunting was more prevalent, but not associated with changes in ACT efficacy. Acute malnutrition is known to impact medicine absorption and metabolism. Further study to inform dose optimisation of ACTs in wasted children is urgently needed.

FUNDING

Bill & Melinda Gates Foundation.

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

Characterisation of populations at risk of sub-optimal dosing of artemisinin-based combination therapy in Africa

Selection of resistant malaria strains occurs when parasites are exposed to inadequate antimalarial drug concentrations. The proportion of uncomplicated falciparum malaria patients at risk of being sub-optimally dosed with the current World Health Organization (WHO) recommended artemisinin-based combination therapies (ACTs) is unknown. This study aims to estimate this proportion and the excess number of treatment failures (recrudescences) associated with sub-optimal dosing in Sub-Saharan Africa. Sub-populations at risk of sub-optimal dosing include wasted children <5 years of age, patients with hyperparasitaemia, pregnant women, people living with HIV, and overweight adults. Country-level data on population structure were extracted from openly accessible data sources. Pooled adjusted Hazard Ratios for PCR-confirmed recrudescence were estimated for each risk group from published meta-analyses using fixed-effect meta-analysis. In 2020, of the estimated 153.1 million uncomplicated P. falciparum malaria patients in Africa, the largest risk groups were the hyperparasitaemic patients (13.2 million, 8.6% of uncomplicated malaria cases) and overweight adults (10.3 million, 6.7% of uncomplicated cases). The estimated excess total number of treatment failures ranged from 0.338 million for a 98% baseline ACT efficacy to 1.352 million for a 92% baseline ACT efficacy. Our study shows that an estimated nearly 1 in 4 people with uncomplicated confirmed P. falciparum malaria in Africa are at risk of receiving a sub-optimal antimalarial drug dosing. This increases the risk of antimalarial drug resistance and poses a serious threat to malaria control and elimination efforts. Changes in antimalarial dosing or treatment duration of current antimalarials may be needed and new antimalarials development should ensure sufficient drug concentration levels in these sub-populations that carry a high malaria burden.

In Vitro and In Vivo Antimalarial Activities and Toxicological Assessment of Pogostemon Cablin (Blanco) Benth

The aim of this study was to investigate the antimalarial activities and toxicity of Pogostemon cablin extracts. In vitro activities against the chloroquine-resistant Plasmodium falciparum K1 strain were assessed by using the Plasmodium lactate dehydrogenase enzyme (pLDH) assay, while in vivo activity against the Plasmodium berghei ANKA strain in mice was investigated using a 4-day suppressive test. The in vitro and in vivo toxicity were determined in Vero cells and mice, respectively. The ethanolic extract possessed antimalarial activity with an IC₅₀ of 24.49 ± 0.01 µg/ml, whereas the aqueous extract showed an IC₅₀ of 549.30 ± 0.07 µg/ml. Cytotoxic analyses of the ethanolic and aqueous extracts revealed a nontoxic effect on Vero cells at a concentration of 80 µg/ml. Based on a preliminary study of in vitro antimalarial activity, the ethanolic extract was chosen as a potential agent for further in vivo antimalarial activity analysis in mice. The ethanolic extract, which showed no toxic effect on mice at a dose of 2000 mg/kg body weight, significantly suppressed parasitemia in mice by 38.41%, 45.12% and 89.00% at doses of 200, 400 and 600 mg/kg body weight, respectively. In conclusion, this study shows that the ethanolic P. cablin extract possesses in vitro and in vivo antimalarial activity without toxic effects.

The Chagas disease study landscape: A systematic review of clinical and observational antiparasitic treatment studies to assess the potential for establishing an individual participant-level data platform

Background

Chagas disease (CD), caused by the parasite Trypanosoma cruzi, affects ~6–7 million people worldwide. Significant limitations still exist in our understanding of CD. Harnessing individual participant data (IPD) from studies could support more in-depth analyses to address the many outstanding research questions. This systematic review aims to describe the characteristics and treatment practices of clinical studies in CD and assess the breadth and availability of research data for the potential establishment of a data-sharing platform.

Methodology/Principal findings

This review includes prospective CD clinical studies published after 1997 with patients receiving a trypanocidal treatment. The following electronic databases and clinical trial registry platforms were searched: Cochrane Library, PubMed, Embase, LILACS, Scielo, Clintrials.gov, and WHO ICTRP.

Of the 11,966 unique citations screened, 109 (0.9%) studies (31 observational and 78 interventional) representing 23,116 patients were included. Diagnosis for patient enrolment required 1 positive test result in 5 (4.6%) studies (2 used molecular method, 1 used molecular and serology, 2 used serology and parasitological methods), 2 in 60 (55.0%), 3 in 14 (12.8%) and 4 or more in 4 (3.7%) studies. A description of treatment regimen was available for 19,199 (83.1%) patients, of whom 14,605 (76.1%) received an active treatment and 4,594 (23.9%) were assigned to a placebo/no-treatment. Of the 14,605 patients who received an active treatment, benznidazole was administered in 12,467 (85.4%), nifurtimox in 825 (5.6%), itraconazole in 284 (1.9%), allopurinol in 251 (1.7%) and other drugs in 286 (1.9%). Assessment of efficacy varied largely and was based primarily on biological outcome; parasitological efficacy relied on serology in 67/85 (78.8%) studies, molecular methods in 52/85 (61.2%), parasitological in 34/85 (40.0%), microscopy in 3/85 (3.5%) and immunohistochemistry in 1/85 (1.2%). The median time at which parasitological assessment was carried out was 79 days [interquartile range (IQR): 30–180] for the first assessment, 180 days [IQR: 60–500] for second, and 270 days [IQR: 18–545] for the third assessment.

Conclusions/Significance

This review demonstrates the heterogeneity of clinical practice in CD treatment and in the conduct of clinical studies. The sheer volume of potential IPD identified demonstrates the potential for development of an IPD platform for CD and that such efforts would enable in-depth analyses to optimise the limited pharmacopoeia of CD and inform prospective data collection.

Chagas disease, also known as American trypanosomiasis, is a neglected tropical disease transmitted by triatomine insects, first identified in 1909. Chagas disease affects approximately 6–7 million people globally and is highly prevalent in Latin America where most cases are reported. However, there is increasing evidence that Chagas disease is now an important public health issue outside the “classical” endemic countries due to population migration. Our understanding of Chagas disease, including its pathologies and factors relating to progression, remains to date limited, and is also challenged by lack of diagnosis and highly effective treatment. This systematic review aims to describe studies with Chagas patients receiving antiparasitic treatment. Databases were searched for relevant studies published after 1997, and the results of these searches were screened.

Although a large volume of studies was identified in the review, heterogeneity was observed in study design, diagnostic methods, outcome assessment, and treatment regimens. While this aspect will be a limitation in pooling individual patient data, the volume of data available should allow sufficient comparison to form the basis of guidelines for future studies. The results of this review demonstrate that development of a Chagas disease data platform for clinical research would enable optimisation of existing data to strengthen evidence for the treatment and diagnosis of Chagas disease.

Increased Sensitivity of Plasmodium falciparum to Artesunate/Amodiaquine Despite 14 Years as First-Line Malaria Treatment, Zanzibar

Artemisinin-based combination therapies (ACTs) are first-line treatments for uncomplicated Plasmodium falciparum malaria. ACT resistance is spreading in Asia but not yet in Africa. Reduced effects of ACT partner drugs have been reported but with little information regarding widely used artesunate/amodiaquine (ASAQ). We studied its efficacy in Zanzibar after 14 years as first-line treatment directly by an in vivo, single-armed trial and indirectly by prevalences of different genotypes in the P. falciparum chloroquine-resistance transporter, multidrug-resistance 1, and Kelch 13 propeller domain genes. In vivo efficacy was higher during 2017 (100%; 95% CI 97.4%-100%) than during 2002-2005 (94.7%; 95% CI 91.9%-96.7%) (p = 0.003). Molecular findings showed no artemisinin resistance-associated genotypes and major increases in genotypes associated with high sensitivity/efficacy for amodiaquine than before ASAQ was introduced. Thus, the efficacy of ASAQ is maintained and appears to be increased after long-term use in contrast to what is observed for other ACTs used in Africa.

Malaria epidemiology and anti-malarial drug efficacy in Guinea: a review of clinical and molecular studies

Malaria is one of the leading causes of mortality and morbidity in Guinea. The entire country is considered at risk of the disease. Transmission occurs all year round with peaks occurring from July through October with Plasmodium falciparum as the primary parasite species. Chloroquine (CQ) was the first-line drug against uncomplicated P. falciparum in Guinea until 2005, prior to the adoption of artemisinin-based combination therapy (ACT). In this review, data on therapeutic efficacy of CQ and artemisinin-based combinations reported in published literature is summarized. Against CQ, a failure rate of 27% (12/44) was reported in a study in 1992; a median failure rate of 15.6% [range: 7.7–28.3; 8 studies] was observed during 1996–2001, and 81% (17/21) of the patients failed to clear parasitaemia in a study conducted in 2007. For artemisinin-based combinations, three published studies were identified (1495 patients; 2004–2016); all three studies demonstrated day 28 polymerase chain reaction corrected efficacy > 95%. One study characterized kelch-13 mutations (389 tested; samples collected in 2016) with no evidence of mutations currently known to be associated with artemisinin resistance. The impact of the ongoing COVID-19 pandemic and widespread usage of counterfeit medicines are immediate challenges to malaria control activities in Guinea.

Pharmacokinetic profile of amodiaquine and its active metabolite desethylamodiaquine in Ghanaian patients with uncomplicated falciparum malaria

Background

Accurate measurement of anti-malarial drug concentrations in therapeutic efficacy studies is essential to distinguish between inadequate drug exposure and anti-malarial drug resistance, and to inform optimal anti-malarial dosing in key target population groups.

Methods

A sensitive and selective LC–MS/MS method was developed and validated for the simultaneous determination of amodiaquine and its active metabolite, desethylamodiaquine, and used to describe their pharmacokinetic parameters in Ghanaian patients with uncomplicated falciparum malaria treated with the fixed-dose combination, artesunate-amodiaquine.

Results

The day-28 genotype-adjusted adequate clinical and parasitological response rate in 308 patients studied was > 97% by both intention-to-treat and per-protocol analysis. After excluding 64 patients with quantifiable amodiaquine concentrations pre-treatment and 17 with too few quantifiable concentrations, the pharmacokinetic analysis included 227 patients (9 infants, 127 aged 1–4 years, 91 aged ≥ 5 years). Increased median day-3 amodiaquine concentrations were associated with a lower risk of treatment failure [HR 0.87 (95% CI 0.78–0.98), p = 0.021]. Amodiaquine exposure (median AUC_0-∞) was significantly higher in infants (4201 ng h/mL) and children aged 1–5 years (1994 ng h/mL) compared to older children and adults (875 ng h/mL, p = 0.001), even though infants received a lower mg/kg amodiaquine dose (median 25.3 versus 33.8 mg/kg in older patients). Desethylamodiaquine AUC_0-∞ was not significantly associated with age. No significant safety concerns were identified.

Conclusions

Efficacy of artesunate-amodiaquine at currently recommended dosage regimens was high across all age groups. Reassuringly, amodiaquine and desethylamodiaquine exposure was not reduced in underweight-for-age young children or those with high parasitaemia, two of the most vulnerable target populations. A larger pharmacokinetic study with close monitoring of safety, including full blood counts and liver function tests, is needed to confirm the higher amodiaquine exposure in infants, understand any safety implications and assess whether dose optimization in this vulnerable, understudied population is needed.

Treatment and prevention of malaria in children

Malaria disproportionately affects children younger than 5 years. Falciparum malaria is responsible for more than 200 000 child deaths per year in Africa and vivax malaria is well documented as a cause of severe anaemia and excess mortality in children in Asia and Oceania. For the treatment of malaria in children, paediatric dosing recommendations for several agents, including parenteral artesunate and dihydroartemisinin-piperaquine, have belatedly been shown to be suboptimal. Worsening antimalarial resistance in Plasmodium falciparum in the Greater Mekong Subregion threatens to undermine global efforts to control malaria. Triple antimalarial combination therapies are being evaluated to try to impede this threat. The RTS,S/AS01 vaccine gives partial protection against falciparum malaria and is being evaluated in large, pilot studies in Ghana, Malawi, and Kenya as a complementary tool to other preventive measures. Seasonal malaria chemoprevention in west Africa has resulted in declines in malaria incidence and deaths and there is interest in scaling up efforts by expanding the age range of eligible recipients. Preventing relapse in Plasmodium vivax infection with primaquine is challenging because treating children who have G6PD deficiency with primaquine can cause acute haemolytic anaemia. The safety of escalating dose regimens for primaquine is being studied to mitigate this risk.

The WorldWide Antimalarial Resistance Network Clinical Trials Publication Library: A Live, Open-Access Database of Plasmodium Treatment Efficacy Trials

Parasite resistance to antimalarial drugs poses a serious threat to malaria control. The WorldWide Antimalarial Resistance Network (WWARN) aims to provide a collaborative platform to support the global malaria research effort. Here, we describe the “WWARN clinical trials publication library,” an open-access, up-to-date resource to streamline the synthesis of antimalarial safety and efficacy data. A series of iteratively refined database searches were conducted to identify prospective clinical trials assessing antimalarial drug efficacy with at least 28 days of follow-up. Of approximately 45,000 articles screened, 1,221 trials published between 1946 and 2018 were identified, representing 2,339 treatment arms and 323,819 patients. In trials from endemic locations, 75.7% (787/1,040) recruited patients with Plasmodium falciparum, 17.0% (177/1,040) Plasmodium vivax, 6.9% (72/1,040) both, and 0.4% (4/1,040) other Plasmodium species; 57.2% (585/1,022) of trials included under-fives and 5.3% (55/1,036) included pregnant women. In Africa, there has been a marked increase in both P. falciparum and P. vivax studies over the last two decades. The WHO-recommended artemisinin-based combination therapies alone or with a gametocidal drug were assessed in 39.5% (705/1,783) of P. falciparum treatment arms and 10.5% (45/429) of P. vivax arms, increasing to 78.0% (266/341) and 22.9% (27/118), respectively, in the last five years. The library is a comprehensive, open-access tool that can be used by the malaria community to explore the collective knowledge on antimalarial efficacy (available at https://www.wwarn.org/tools-resources/literature-reviews/wwarn-clinical-trials-publication-library). It is the first of its kind in the field of global infectious diseases, and lessons learnt in its creation can be adapted to other infectious diseases.

The duration of chemoprophylaxis against malaria after treatment with artesunate-amodiaquine and artemether-lumefantrine and the effects of pfmdr1 86Y and pfcrt 76T: a meta-analysis of individual patient data

BACKGROUND

The majority of Plasmodium falciparum malaria cases in Africa are treated with the artemisinin combination therapies artemether-lumefantrine (AL) and artesunate-amodiaquine (AS-AQ), with amodiaquine being also widely used as part of seasonal malaria chemoprevention programs combined with sulfadoxine-pyrimethamine. While artemisinin derivatives have a short half-life, lumefantrine and amodiaquine may give rise to differing durations of post-treatment prophylaxis, an important additional benefit to patients in higher transmission areas.

METHODS

We analyzed individual patient data from 8 clinical trials of AL versus AS-AQ in 12 sites in Africa (n = 4214 individuals). The time to PCR-confirmed reinfection after treatment was used to estimate the duration of post-treatment protection, accounting for variation in transmission intensity between settings using hidden semi-Markov models. Accelerated failure-time models were used to identify potential effects of covariates on the time to reinfection. The estimated duration of chemoprophylaxis was then used in a mathematical model of malaria transmission to determine the potential public health impact of each drug when used for first-line treatment.

RESULTS

We estimated a mean duration of post-treatment protection of 13.0 days (95% CI 10.7-15.7) for AL and 15.2 days (95% CI 12.8-18.4) for AS-AQ overall. However, the duration varied significantly between trial sites, from 8.7-18.6 days for AL and 10.2-18.7 days for AS-AQ. Significant predictors of time to reinfection in multivariable models were transmission intensity, age, drug, and parasite genotype. Where wild type pfmdr1 and pfcrt parasite genotypes predominated (<=20% 86Y and 76T mutants, respectively), AS-AQ provided ~ 2-fold longer protection than AL. Conversely, at a higher prevalence of 86Y and 76T mutant parasites (> 80%), AL provided up to 1.5-fold longer protection than AS-AQ. Our simulations found that these differences in the duration of protection could alter population-level clinical incidence of malaria by up to 14% in under-5-year-old children when the drugs were used as first-line treatments in areas with high, seasonal transmission.

CONCLUSION

Choosing a first-line treatment which provides optimal post-treatment prophylaxis given the local prevalence of resistance-associated markers could make a significant contribution to reducing malaria morbidity.

Dealing with indeterminate outcomes in antimalarial drug efficacy trials: a comparison between complete case analysis, multiple imputation and inverse probability weighting

BACKGROUND

Antimalarial clinical efficacy studies for uncomplicated Plasmodium falciparum malaria frequently encounter situations in which molecular genotyping is unable to discriminate between parasitic recurrence, either new infection or recrudescence. The current WHO guideline recommends excluding these individuals with indeterminate outcomes in a complete case (CC) analysis. Data from the four artemisinin-based combination (4ABC) trial was used to compare the performance of multiple imputation (MI) and inverse probability weighting (IPW) against the standard CC analysis for dealing with indeterminate recurrences.

METHODS

3369 study participants from the multicentre study (4ABC trial) with molecularly defined parasitic recurrence treated with three artemisinin-based combination therapies were used to represent a complete dataset. A set proportion of recurrent infections (10, 30 and 45%) were reclassified as missing using two mechanisms: a completely random selection (mechanism 1); missingness weakly dependent (mechanism 2a) and strongly dependent (mechanism 2b) on treatment and transmission intensity. The performance of MI, IPW and CC approaches in estimating the Kaplan-Meier (K-M) probability of parasitic recrudescence at day 28 was then compared. In addition, the maximum likelihood estimate of the cured proportion was presented for further comparison (analytical solution). Performance measures (bias, relative bias, standard error and coverage) were reported as an average from 1000 simulation runs.

RESULTS

The CC analyses resulted in absolute underestimation of K-M probability of day 28 recrudescence by up to 1.7% and were associated with reduced precision and poor coverage across all the scenarios studied. Both MI and IPW method performed better (greater consistency and greater efficiency) compared to CC analysis. In the absence of censoring, the analytical solution provided the most consistent and accurate estimate of cured proportion compared to the CC analyses.

CONCLUSIONS

The widely used CC approach underestimates antimalarial failure; IPW and MI procedures provided efficient and consistent estimates and should be considered when reporting the results of antimalarial clinical trials, especially in areas of high transmission, where the proportion of indeterminate outcomes could be large. The analytical solution estimating the cured proportion could provide an alternative approach, in scenarios with minimal censoring due to loss to follow-up or new infections.

Equitable data sharing: challenges and suggestions for ways forward

Data sharing is increasingly mandated by health research funders and publishers. In the context of data collected in low-resource settings, concerns have been raised regarding inequitable opportunities to engage in secondary use of data between researchers in well-resourced and resource-limited settings. In this context, we present three case studies and their issues related to equity: the multicountry Antenatal Corticosteroid Trial, health research in the Dominican Repulic and the WorldWide Antimalarial Resistance Network. These case studies were discussed at the 2018 Global Forum for Bioethics in Research in South Africa, focussing on the theme “The ethics of data sharing and biobanking in health research”. The case studies provide concrete examples of real challenges such as lack of prior consent for data sharing, potential for misinterpretation of data by secondary users and limited capacity of researchers in low-resource settings to conduct secondary analyses. We conclude by suggesting ways forward. We stress the importance of capacity building and investments in data management and data science skills, and in data sharing platforms supporting poverty-related disease research. In addition, we recommend that there should be incentives to promote data sharing and that research groups and institutions establish their own data sharing policies  tailored to their context, data and community while persuing harmonization with existing policies as much as possible. We also think that international guidelines on authorship criteria should be revisited. For new studies, researchers should obtain consent for sharing of participants’ data with secondary users. Lastly we recommend that community and stakeholder engagement be conducted to improve the consent process and identify what might be sensitive data to mitigate any potential harms to data subjects and their communities.

Strength in Numbers: The WWARN Case Study of Purpose-Driven Data Sharing

Data are the basis for all scientific output. The sharing of data supporting that output is an important aspect of scientific communication, and is increasingly required by funders and publishers. Yet, academic advancement seldom recognizes or rewards data sharing. This article argues that although mandating data sharing will increase the amount of data available, this will not necessarily enable or encourage the secondary analyses needed to achieve its purported public good. We, therefore, need to build models that maximize the efficiency of processes for data collation and curation, and genuinely reward those engaged in data sharing and reuse. The WorldWide Antimalarial Resistance Network has 10 years of experience as a data platform, and its study group approach provides an example of how some of the challenges in equitable and impactful data-sharing and secondary use can be addressed, with a focus on the priorities of researchers in resource-limited settings.

Safety and tolerability of artesunate-amodiaquine, artemether-lumefantrine and quinine plus clindamycin in the treatment of uncomplicated Plasmodium falciparum malaria in Kinshasa, the Democratic Republic of the Congo

INTRODUCTION

Artemisinin-based combination therapy is currently the best option for the treatment of uncomplicated malaria. Quinine is recommended as a rescue treatment. Safety information during repeated treatment with the same drug is scarce. We report safety data from the Quinact randomized clinical trial (RCT) that was designed to assess efficacy and safety of artesunate-amodiaquine (ASAQ), artemether-lumefantrine (AL) and quinine+clindamycin (QnC).

METHODOLOGY

Males and females aged 12 to 59 months with uncomplicated malaria were treated with ASAQ and followed up during 42 days (preRCT). Clinical failures were randomized to one of the 3 treatments and followed up for 28 days (RCT). Subsequent failures were repeatedly treated with ASAQ several times as needed (postRCT1, postRCT2 and so on) until a 28-days follow up period without parasitaemia.

RESULTS

Eight hundred and sixty-five, 242 and 64 patients were recruited respectively in preRCT, RCT and postRCTs. In preRCT, 433 (50.0%) patients experienced at least one drug-related adverse event (AE). The most reported AEs were anorexia (22.9%), asthenia (19.4%), and abnormal behavior (14.6%). Twenty-nine AEs (3.5%) were reported to be severe. In RCT, at least one drug-related AE was reported in 54.7%, 21.5% and 40.0% of patient randomized respectively to ASAQ, AL and QnC (p<0.001). During postRCT1 (n = 64), postRCT 2 (n = 17) and postRCT3 (n = 7), respectively 32.8%, 35.3% and 71.4% of patients experienced at least one drug-related AE. Three serious adverse events occurred but not judged related to study medication.

CONCLUSION

The proportion of AEs did not increase over the treatment courses with ASAQ. However, continuous monitoring is important.

The effect of dose on the antimalarial efficacy of artesunate-mefloquine against Plasmodium falciparum malaria: a protocol for systematic review and individual patient data (IPD) meta-analysis

INTRODUCTION

Antimalarial posology based on weight bands leaves patients at the margins vulnerable to receiving either lower or higher weight-adjusted (mg/kg) dosages. This article aims to describe the protocol for systematic review and individual patient meta-analysis (MA) for a study of the distribution of artesunate and mefloquine dosage administered in patients with uncomplicated Plasmodium falciparum malaria treated with an artesunate-mefloquine (AS-MQ) regimen. Relationship between mg/kg dose and therapeutic outcomes will be assessed through a one-stage individual participant data (IPD) MA.

METHODS AND ANALYSIS

Therapeutic efficacy studies with the AS-MQ regimen will be identified by searching the following databases: PUBMED, EMBASE and Web of Science. The corresponding authors of the relevant studies will be requested to share the IPD for the purpose of this MA to a secured repository. All available studies will be standardised using a common data management protocol and pooled into a single database. The relationship between mg/kg dosage and treatment failures will be assessed using a Cox regression model with study sites considered as a shared frailty term. Safety parameters will be explored where available.

ETHICS AND DISSEMINATION

This IPD MA met the criteria for waiver of ethical review as defined by the Oxford Tropical Research Ethics Committee as the research consisted of secondary analysis of existing anonymous data. The results of this analysis will be disseminated at conferences, WorldWide Antimalarial Resistance Network website and any peer-reviewed publication arising will be made open source.

PROSPERO REGISTRATION NUMBER

CRD42018103776.

Evaluating antimalarial efficacy in single-armed and comparative drug trials using competing risk survival analysis: a simulation study

BACKGROUND

Antimalarial efficacy studies in patients with uncomplicated Plasmodium falciparum are confounded by a new infection (a competing risk event) since this event can potentially preclude a recrudescent event (primary endpoint of interest). The current WHO guidelines recommend censoring competing risk events when deriving antimalarial efficacy. We investigated the impact of considering a new infection as a competing risk event on the estimation of antimalarial efficacy in single-armed and comparative drug trials using two simulation studies.

METHODS

The first simulation study explored differences in the estimates of treatment failure for areas of varying transmission intensities using the complement of the Kaplan-Meier (K-M) estimate and the Cumulative Incidence Function (CIF). The second simulation study extended this to a comparative drug efficacy trial for comparing the K-M curves using the log-rank test, and Gray's k-sample test for comparing the equality of CIFs.

RESULTS

The complement of the K-M approach produced larger estimates of cumulative treatment failure compared to the CIF method; the magnitude of which was correlated with the observed proportion of new infection and recrudescence. When the drug efficacy was 90%, the absolute overestimation in failure was 0.3% in areas of low transmission rising to 3.1% in the high transmission settings. In a scenario which is most likely to be observed in a comparative trial of antimalarials, where a new drug regimen is associated with an increased (or decreased) rate of recrudescences and new infections compared to an existing drug, the log-rank test was found to be more powerful to detect treatment differences compared to the Gray's k-sample test.

CONCLUSIONS

The CIF approach should be considered for deriving estimates of antimalarial efficacy, in high transmission areas or for failing drugs. For comparative studies of antimalarial treatments, researchers need to select the statistical test that is best suited to whether the rate or cumulative risk of recrudescence is the outcome of interest, and consider the potential differing prophylactic periods of the antimalarials being compared.

Global Spread of Mutant PfCRT and Its Pleiotropic Impact on Plasmodium falciparum Multidrug Resistance and Fitness

The global spread of Plasmodium falciparum chloroquine resistance transporter (PfCRT) variant haplotypes earlier caused the widespread loss of chloroquine (CQ) efficacy. In Asia, novel PfCRT mutations that emerged on the Dd2 allelic background have recently been implicated in high-level resistance to piperaquine, and N326S and I356T have been associated with genetic backgrounds in which resistance emerged to artemisinin derivatives. By analyzing large-scale genome sequencing data, we report that the predominant Asian CQ-resistant Dd2 haplotype is undetectable in Africa. Instead, the GB4 and previously unexplored Cam783 haplotypes predominate, along with wild-type, drug-sensitive PfCRT that has reemerged as the major haplotype. To interrogate how these alleles impact drug susceptibility, we generated pfcrt-modified isogenic parasite lines spanning the mutational interval between GB4 and Dd2, which includes Cam783 and involves amino acid substitutions at residues 326 and 356. Relative to Dd2, the GB4 and Cam783 alleles were observed to mediate lower degrees of resistance to CQ and the first-line drug amodiaquine, while resulting in higher growth rates. These findings suggest that differences in growth rates, a surrogate of parasite fitness, influence selection in the context of African infections that are frequently characterized by high transmission rates, mixed infections, increased immunity, and less recourse to treatment. We also observe that the Asian Dd2 allele affords partial protection against piperaquine yet does not directly impact artemisinin efficacy. Our results can help inform the regional recommendations of antimalarials, whose activity is influenced by and, in certain cases, enhanced against select PfCRT variant haplotypes.IMPORTANCE Our study defines the allelic distribution of pfcrt, an important mediator of multidrug resistance in Plasmodium falciparum, in Africa and Asia. We leveraged whole-genome sequence analysis and gene editing to demonstrate how current drug combinations can select different allelic variants of this gene and shape region-specific parasite population structures. We document the ability of PfCRT mutations to modulate parasite susceptibility to current antimalarials in dissimilar, pfcrt allele-specific ways. This study underscores the importance of actively monitoring pfcrt genotypes to identify emerging patterns of multidrug resistance and help guide region-specific treatment options.

Population Pharmacokinetics of the Antimalarial Amodiaquine: a Pooled Analysis To Optimize Dosing

Amodiaquine plus artesunate is the recommended antimalarial treatment in many countries where malaria is endemic. However, pediatric doses are largely based on a linear extrapolation from adult doses.

Amodiaquine plus artesunate is the recommended antimalarial treatment in many countries where malaria is endemic. However, pediatric doses are largely based on a linear extrapolation from adult doses. We pooled data from previously published studies on the pharmacokinetics of amodiaquine, to optimize the dose across all age groups. Adults and children with uncomplicated malaria received daily weight-based doses of amodiaquine or artesunate-amodiaquine over 3 days. Plasma concentration-time profiles for both the parent drug and the metabolite were characterized using nonlinear mixed-effects modeling. Amodiaquine pharmacokinetics were adequately described by a two-compartment disposition model, with first-order elimination leading to the formation of desethylamodiaquine, which was best described by a three-compartment disposition model. Body size and age were the main covariates affecting amodiaquine clearance. After adjusting for the effect of weight, clearance rates for amodiaquine and desethylamodiaquine reached 50% of adult maturation at 2.8 months (95% confidence interval [CI], 1.5 to 3.7 months) and 3.9 months (95% CI, 2.6 to 5.3 months) after birth, assuming that the baby was born at term. Bioavailability was 22.4% (95% CI, 15.6 to 31.9%) lower at the start of treatment than during convalescence, which suggests a malaria disease effect. Neither the drug formulation nor the hemoglobin concentration had an effect on any pharmacokinetic parameters. Results from simulations showed that current manufacturer dosing recommendations resulted in low desethylamodiaquine exposure in patients weighing 8 kg, 15 to 17 kg, 33 to 35 kg, and >62 kg compared to that in a typical 50-kg patient. We propose possible optimized dosing regimens to achieve similar drug exposures among all age groups, which require further validation.

Pharmacokinetics and Safety Profile of Artesunate-Amodiaquine Coadministered with Antiretroviral Therapy in Malaria-Uninfected HIV-Positive Malawian Adults

There are limited data on the pharmacokinetic and safety profiles of artesunate-amodiaquine in human immnunodeficiency virus-infected (HIV⁺) individuals receiving antiretroviral therapy. In a two-step intensive sampling pharmacokinetic trial, we compared the area under the concentration-time curve from 0 to 28 days (AUC_0–28) of an active metabolite of amodiaquine, desethylamodiaquine, and treatment-emergent adverse events between antiretroviral therapy-naive HIV⁺ adults and those taking nevirapine and ritonavir-boosted lopinavir-based antiretroviral therapy. In step 1, malaria-uninfected adults (n = 6/arm) received half the standard adult treatment regimen of artesunate-amodiaquine. In step 2, another cohort (n = 25/arm) received the full regimen. In step 1, there were no safety signals or significant differences in desethylamodiaquine AUC_0–28 among participants in the ritonavir-boosted lopinavir, nevirapine, and antiretroviral therapy-naive arms. In step 2, compared with those in the antiretroviral therapy-naive arm, participants in the ritonavir-boosted lopinavir arm had 51% lower desethylamodiaquine AUC_0–28, with the following geometric means (95% confidence intervals [CIs]): 23,822 (17,458 to 32,506) versus 48,617 (40,787 to 57,950) ng · h/ml (P < 0.001). No significant differences in AUC_0–28 were observed between nevirapine and antiretroviral therapy-naive arms. Treatment-emergent transaminitis was higher in the nevirapine (20% [5/25]) than the antiretroviral therapy-naive (0.0% [0/25]) arm (risk difference, 20% [95% CI, 4.3 to 35.7]; P = 0.018). The ritonavir-boosted lopinavir antiretroviral regimen was associated with reduced desethylamodiaquine exposure, which may compromise artesunate-amodiaquine's efficacy. Coadministration of nevirapine and artesunate-amodiaquine may be associated with hepatoxicity.

Malaria

Following unsuccessful eradication attempts there was a resurgence of malaria towards the end of the 20th century. Renewed control efforts using a range of improved tools, such as long-lasting insecticide-treated bednets and artemisinin-based combination therapies, have more than halved the global burden of disease, but it remains high with 445 000 deaths and more than 200 million cases in 2016. Pitfalls in individual patient management are delayed diagnosis and overzealous fluid resuscitation in severe malaria. Even in the absence of drug resistance, parasite recurrence can occur, owing to high parasite densities, low host immunity, or suboptimal drug concentrations. Malaria elimination is firmly back as a mainstream policy but resistance to the artemisinin derivatives, their partner drugs, and insecticides present major challenges. Vaccine development continues on several fronts but none of the candidates developed to date have been shown to provide long-lasting benefits at a population level. Increased resources and unprecedented levels of regional cooperation and societal commitment will be needed if further substantial inroads into the malaria burden are to be made.

Tools for surveillance of anti-malarial drug resistance: an assessment of the current landscape

To limit the spread and impact of anti-malarial drug resistance and react accordingly, surveillance systems able to detect and track in real-time its emergence and spread need to be strengthened or in some places established. Currently, surveillance of anti-malarial drug resistance is done by any of three approaches: (1) in vivo studies to assess the efficacy of drugs in patients; (2) in vitro/ex vivo studies to evaluate parasite susceptibility to the drugs; and/or (3) molecular assays to detect validated gene mutations and/or gene copy number changes that are associated with drug resistance. These methods are complementary, as they evaluate different aspects of resistance; however, standardization of methods, especially for in vitro/ex vivo and molecular techniques, is lacking. The World Health Organization has developed a standard protocol for evaluating the efficacy of anti-malarial drugs, which is used by National Malaria Control Programmes to conduct their therapeutic efficacy studies. Regional networks, such as the East African Network for Monitoring Antimalarial Treatment and the Amazon Network for the Surveillance of Antimalarial Drug Resistance, have been set up to strengthen regional capacities for monitoring anti-malarial drug resistance. The Worldwide Antimalarial Resistance Network has been established to collate and provide global spatial and temporal trends information on the efficacy of anti-malarial drugs and resistance. While exchange of information across endemic countries is essential for monitoring anti-malarial resistance, sustainable funding for the surveillance and networking activities remains challenging. The technology landscape for molecular assays is progressing quite rapidly, and easy-to-use and affordable new techniques are becoming available. They also offer the advantage of high throughput analysis from a simple blood spots obtained from a finger prick. New technologies combined with the strengthening of national reference laboratories in malaria-endemic countries through standardized protocols and training plus the availability of a proficiency testing programme, would contribute to the improvement and sustainability of anti-malarial resistance surveillance networks worldwide.

Systematic review of clinical trials assessing the therapeutic efficacy of visceral leishmaniasis treatments: A first step to assess the feasibility of establishing an individual patient data sharing platform

Background

There are an estimated 200,000 to 400,000 cases of visceral leishmaniasis (VL) annually. A variety of factors are taken into account when considering the best therapeutic options to cure a patient and reduce the risk of resistance, including geographical area, malnourishment and HIV coinfection. Pooled analyses combine data from many studies to answer specific scientific questions that cannot be answered with individual studies alone. However, the heterogeneity of study design, data collection, and analysis often makes direct comparison difficult. Individual Participant Data (IPD) files can be standardised and analysed, allowing detailed analysis of this merged larger pool, but only a small fraction of systematic reviews and meta-analyses currently employ pooled analysis of IPD. We conducted a systematic literature review to identify published studies and studies reported in clinical trial registries to assess the feasibility of developing a VL data sharing platform to facilitate an IPD-based analysis of clinical trial data. Studies conducted between 1983 to 2015 that reported treatment outcome were eligible.

Principal findings

From the 2,271 documents screened, 145 published VL clinical trials were identified, with data from 26,986 patients. Methodologies varied for diagnosis and treatment outcomes, but overall the volume of data potentially available on different drugs and dose regimens identified hundreds or possibly thousands of patients per arm suitable for IPD pooled meta-analyses.

Conclusions

A VL data sharing platform would provide an opportunity to maximise scientific use of available data to enable assessment of treatment efficacy, contribute to evidence-based clinical management and guide optimal prospective data collection.

Visceral leishmaniasis (VL) is a vector borne infectious disease caused by protozoan parasites transmitted by sand flies. The disease affects both immunocompetent and immunocompromised patients, predominantly occurring in remote regions in specific areas of Africa, Asia and South America. There are an estimated 200,000 to 400,000 cases each year, resulting in 20,000 to 40,000 deaths. Few therapeutic options are available, and these are typically expensive, not adapted for field use and cause life-threatening side effects. Treatment of the disease is further complicated by apparent variation in drug efficacy in patients from different regions. A comprehensive understanding of treatment outcomes is essential to ensure more effective treatment and control of VL. This systematic review was undertaken to determine whether sufficient relevant data are available to warrant creation of a data sharing platform for harmonisation and comparison of VL clinical trials. We identified 145 published VL clinical trials, which together have enrolled 26,986 patients. There was sufficient consistency in the trial methods to support pooling of these individual patient data. The findings of this review suggest that a VL data sharing platform would enable meaningful meta-analysis of VL treatment trials, which could inform treatment allocation, further drug development, and guide improved disease control.

Modelling the therapeutic dose range of single low dose primaquine to reduce malaria transmission through age-based dosing

BACKGROUND

Low-dose primaquine is a key candidate for use in malaria transmission reduction and elimination campaigns such as mass drug administration (MDA). Uncertainty about the therapeutic dose range (TDR) required for general and paediatric populations challenge the implementation of the World Health Organisation's recommendation to add 0.25 mg/kg to current standard antimalarial treatment in such settings. Modelling work shows that for low-dose primaquine to have an impact, high efficacy and extensive population coverage are needed. In practice, age-based dose regimens, often used in MDA, could lead to safety concerns and a different effectiveness profile. We aimed to define TDRs for primaquine and to assess dosing accuracy of age-based dose regimens.

METHODS

Optimised regional age-based dosing regimens for low-dose primaquine were developed in steps. First, we identified potential TDR options based on suggested published efficacy and safety thresholds (i.e. 0.1-0.4, 0.125-0.375, 0.15-0.35 mg/kg). We then used our previously defined weight-for-age growth references and age-based dose optimisation tool to model predicted regimen accuracies for Africa, Asia and Latin America based on low-dose primaquine tablets (3.75 mg and 7.5 mg) currently under development by Sanofi while employing the identified dose range options and pre-specified regimen characteristics.

RESULTS

Dose regimens employing TDRs of 0.1-0.4 and 0.125-0.375 mg/kg had the highest average predicted dose accuracies in all regions with the widest dose range of 0.1-0.4 mg/kg resulting in ≥99% dose accuracy in all three regions. The narrower 0.15-0.35 mg/kg range was on average predicted to correctly dose 91.4% of the population in Africa, 93.2% in Asia and 92.6% in Latin America. This range would prescribe ≥20% of 3-year-olds doses below 0.15 mg/kg and ≥20% of 11-year-olds doses above 0.35 mg/kg. Widening the TDR from 0.15-0.35 to 0.1-0.4 mg/kg increased the dose accuracy by ≥20% in Africa, ≥15% in Asia and ≥10% in Latin America.

CONCLUSION

Optimised age-based dose regimens derived from wider TDRs are predicted to attain the dose accuracies required for effective MDA in malaria transmission reduction and elimination settings. We highlight the need for a clearly defined TDR and for safety and efficacy trials to focus on doses compatible with age-based dosing often employed in such settings.

Efficacy of artemether-lumefantrine, artesunate-amodiaquine, and dihydroartemisinin-piperaquine for treatment of uncomplicated Plasmodium falciparum malaria in Angola, 2015

BACKGROUND

Recent anti-malarial resistance monitoring in Angola has shown efficacy of artemether-lumefantrine (AL) in certain sites approaching the key 90% lower limit of efficacy recommended for artemisinin-based combination therapy. In addition, a controversial case of malaria unresponsive to artemisinins was reported in a patient infected in Lunda Sul Province in 2013.

METHODS

During January-June 2015, investigators monitored the clinical and parasitological response of children with uncomplicated Plasmodium falciparum infection treated with AL, artesunate-amodiaquine (ASAQ), or dihydroartemisinin-piperaquine (DP). The study comprised two treatment arms in each of three provinces: Benguela (AL, ASAQ), Zaire (AL, DP), and Lunda Sul (ASAQ, DP). Samples from treatment failures were analysed for molecular markers of resistance for artemisinin (K13) and lumefantrine (pfmdr1).

RESULTS

A total of 467 children reached a study endpoint. Fifty-four treatment failures were observed: four early treatment failures, 40 re-infections and ten recrudescences. Excluding re-infections, the 28-day microsatellite-corrected efficacy was 96.3% (95% CI 91-100) for AL in Benguela, 99.9% (95-100) for ASAQ in Benguela, 88.1% (81-95) for AL in Zaire, and 100% for ASAQ in Lunda Sul. For DP, the 42-day corrected efficacy was 98.8% (96-100) in Zaire and 100% in Lunda Sul. All treatment failures were wild type for K13, but all AL treatment failures had pfmdr1 haplotypes associated with decreased lumefantrine susceptibility.

CONCLUSIONS

No evidence was found to corroborate the specific allegation of artemisinin resistance in Lunda Sul. The efficacy below 90% of AL in Zaire matches findings from 2013 from the same site. Further monitoring, particularly including measurement of lumefantrine blood levels, is recommended.

Population Pharmacokinetic Properties of Piperaquine in Falciparum Malaria: An Individual Participant Data Meta-Analysis

BACKGROUND

Artemisinin-based combination therapies (ACTs) are the mainstay of the current treatment of uncomplicated Plasmodium falciparum malaria, but ACT resistance is spreading across Southeast Asia. Dihydroartemisinin-piperaquine is one of the five ACTs currently recommended by the World Health Organization. Previous studies suggest that young children (<5 y) with malaria are under-dosed. This study utilised a population-based pharmacokinetic approach to optimise the antimalarial treatment regimen for piperaquine.

METHODS AND FINDINGS

Published pharmacokinetic studies on piperaquine were identified through a systematic literature review of articles published between 1 January 1960 and 15 February 2013. Individual plasma piperaquine concentration-time data from 11 clinical studies (8,776 samples from 728 individuals) in adults and children with uncomplicated malaria and healthy volunteers were collated and standardised by the WorldWide Antimalarial Resistance Network. Data were pooled and analysed using nonlinear mixed-effects modelling. Piperaquine pharmacokinetics were described successfully by a three-compartment disposition model with flexible absorption. Body weight influenced clearance and volume parameters significantly, resulting in lower piperaquine exposures in small children (<25 kg) compared to larger children and adults (≥25 kg) after administration of the manufacturers' currently recommended dose regimens. Simulated median (interquartile range) day 7 plasma concentration was 29.4 (19.3-44.3) ng/ml in small children compared to 38.1 (25.8-56.3) ng/ml in larger children and adults, with the recommended dose regimen. The final model identified a mean (95% confidence interval) increase of 23.7% (15.8%-32.5%) in piperaquine bioavailability between each piperaquine dose occasion. The model also described an enzyme maturation function in very young children, resulting in 50% maturation at 0.575 (0.413-0.711) y of age. An evidence-based optimised dose regimen was constructed that would provide piperaquine exposures across all ages comparable to the exposure currently seen in a typical adult with standard treatment, without exceeding the concentration range observed with the manufacturers' recommended regimen. Limited data were available in infants and pregnant women with malaria as well as in healthy individuals.

CONCLUSIONS

The derived population pharmacokinetic model was used to develop a revised dose regimen of dihydroartemisinin-piperaquine that is expected to provide equivalent piperaquine exposures safely in all patients, including in small children with malaria. Use of this dose regimen is expected to prolong the useful therapeutic life of dihydroartemisinin-piperaquine by increasing cure rates and thereby slowing resistance development. This work was part of the evidence that informed the World Health Organization technical guidelines development group in the development of the recently published treatment guidelines (2015).

Efficacy of artemether-lumefantrine in relation to drug exposure in children with and without severe acute malnutrition: an open comparative intervention study in Mali and Niger

BACKGROUND

Severe acute malnutrition (SAM) affects almost all organs and has been associated with reduced intestinal absorption of medicines. However, very limited information is available on the pharmacokinetic properties of antimalarial drugs in this vulnerable population. We assessed artemether-lumefantrine (AL) clinical efficacy in children with SAM compared to those without.

METHODS

Children under 5 years of age with uncomplicated P. falciparum malaria were enrolled between November 2013 and January 2015 in Mali and Niger, one third with uncomplicated SAM and two thirds without. AL was administered under direct observation with a fat intake consisting of ready-to-use therapeutic food (RUTF - Plumpy'Nut®) in SAM children, twice daily during 3 days. Children were followed for 42 days, with PCR-corrected adequate clinical and parasitological response (ACPR) at day 28 as the primary outcome. Lumefantrine concentrations were assessed in a subset of participants at different time points, including systematic measurements on day 7.

RESULTS

A total of 399 children (360 in Mali and 39 in Niger) were enrolled. Children with SAM were younger than their non-SAM counterparts (mean 17 vs. 28 months, P < 0.0001). PCR-corrected ACPR was 100 % (95 % CI, 96.8-100 %) in SAM at both day 28 and 42, versus 98.8 % (96.4-99.7 %) at day 28 and 98.3 % (95.6-99.4 %) at day 42 in non-SAM (P = 0.236 and 0.168, respectively). Compared to younger children, children older than 21 months experienced more reinfections and SAM was associated with a greater risk of reinfection until day 28 (adjusted hazard ratio = 2.10 (1.04-4.22), P = 0.038). Day 7 lumefantrine concentrations were significantly lower in SAM than non-SAM (median 251 vs. 365 ng/mL, P = 0.049).

CONCLUSIONS

This study shows comparable therapeutic efficacy of AL in children without SAM and in those with SAM when given in combination with RUTF, but a higher risk of reinfection in older children suffering from SAM. This could be associated with poorer exposure to the antimalarials as documented by a lower lumefantrine concentration on day 7.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01958905 , registration date: October 7, 2013.

Fixed-Dose Artesunate-Amodiaquine Combination vs Chloroquine for Treatment of Uncomplicated Blood Stage P. vivax Infection in the Brazilian Amazon: An Open-Label Randomized, Controlled Trial

In the Brazilian Amazon, the artesunate–amodiaquine combination was more effective in preventing Plasmodium vivax recurrence. With a favorable safety profile, this antimalarial treatment proved to be a good first-line alternative. Chloroquine resistance is probably underestimated in the area.

Background.

Despite increasing evidence of the development of Plasmodium vivax chloroquine (CQ) resistance, there have been no trials comparing its efficacy with that of artemisinin-based combination therapies (ACTs) in Latin America.

Methods.

This randomized controlled trial compared the antischizontocidal efficacy and safety of a 3-day supervised treatment of the fixed-dose combination artesunate-amodiaquine Winthrop^® (ASAQ) versus CQ for treatment of uncomplicated P. vivax infection in Manaus, Brazil. Patients were followed for 42 days. Primary endpoints were adequate clinical and parasitological responses (ACPR) rates at day 28. Genotype-adjustment was performed.

Results.

From 2012 to 2013, 380 patients were enrolled. In the per-protocol (PP) analysis, adjusted-ACPR was achieved in 100% (165/165) and 93.6% (161/172) of patients in the ASAQ and CQ arm (difference 6.4%, 95% CI 2.7%; 10.1%) at day 28 and in 97.4% (151/155) and 77.7% (129/166), respectively (difference 19.7%, 95% CI 12.9%; 26.5%), at day 42. Apart from ITT D28 assessment, superiority of ASAQ on ACPR was demonstrated. ASAQ presented faster clearance of parasitaemia and fever. Based on CQ blood level measurements, CQ resistance prevalence was estimated at 11.5% (95% CI: 7.5-17.3) up to day 42. At least one emergent adverse event (AE) was recorded for 79/190 (41x6%) in the ASAQ group and for 85/190 (44x7%) in the CQ group. Both treatments had similar safety profiles.

Conclusions.

ASAQ exhibited high efficacy against CQ resistant P. vivax and is an adequate alternative in the study area. Studies with an efficacious comparator, longer follow-up and genotype-adjustment can improve CQR characterization.

Clinical Trials Registration. NCT01378286.

The clinical impact of artemisinin resistance in Southeast Asia and the potential for future spread

Artemisinins are the most rapidly acting of currently available antimalarial drugs. Artesunate has become the treatment of choice for severe malaria, and artemisinin-based combination therapies (ACTs) are the foundation of modern falciparum malaria treatment globally. Their safety and tolerability profile is excellent. Unfortunately, Plasmodium falciparum infections with mutations in the ‘K13’ gene, with reduced ring-stage susceptibility to artemisinins, and slow parasite clearance in patients treated with ACTs, are now widespread in Southeast Asia. We review clinical efficacy data from the region (2000–2015) that provides strong evidence that the loss of first-line ACTs in western Cambodia, first artesunate-mefloquine and then DHA-piperaquine, can be attributed primarily to K13 mutated parasites. The ring-stage activity of artemisinins is therefore critical for the sustained efficacy of ACTs; once it is lost, rapid selection of partner drug resistance and ACT failure are inevitable consequences. Consensus methods for monitoring artemisinin resistance are now available. Despite increased investment in regional control activities, ACTs are failing across an expanding area of the Greater Mekong subregion. Although multiple K13 mutations have arisen independently, successful multidrug-resistant parasite genotypes are taking over and threaten to spread to India and Africa. Stronger containment efforts and new approaches to sustaining long-term efficacy of antimalarial regimens are needed to prevent a global malaria emergency.

Artemisinin resistance in Plasmodium falciparum malaria is causing failure of artemisinin-based combination therapies across an expanding area of Southeast Asia, undermining control and elimination efforts. The potential global consequences can only be avoided by new approaches that ensure sustained efficacy for antimalarial regimens in malaria affected populations.

Uncomplicated Clinical Malaria Features, the Efficacy of Artesunate-Amodiaquine and Their Relation with Multiplicity of Infection in the Democratic Republic of Congo

Background

In the Democratic Republic of Congo, artesunate-amodiaquine (ASAQ) is the first-line medication recommended for uncomplicated malaria treatment. We conducted a study in Kinshasa to describe the clinical features of the disease and assess the efficacy of ASAQ and its impact on the multiplicity of infection in children with uncomplicated malaria.

Methods

Children aged 12 to 59 months with uncomplicated P. falciparum malaria were treated with ASAQ and followed up passively for 42 days. To distinguish new infections from recrudescent parasites, samples were genotyped using a stepwise strategy with three molecular markers (GLURP, MSP2 and MSP1). We then assessed PCR-corrected and -uncorrected day-42 cure rates and multiplicity of infection (MOI).

Results

In total, 2,796 patients were screened and 865 enrolled in the study. Clinical features were characterized by history of fever (100%), coryza (59.9%) and weakness (59.4%). The crude and PCR-corrected efficacies of ASAQ were 55.3% (95%CI: 51.8–58.8) and 92.8% (95%CI: 91.0–94.6) respectively, as 83.6% (95%CI: 79.1–87.2) of the recurrences were new infections. Compared to monoclonal infections, polyclonal infections were more frequent at enrollment (88.1%) and in recurrences (80.1%; p = 0.005; OR: 1.8, 95%CI: 1.20–2.8). The median MOI at enrollment (MOI = 3.7; IQR: 0.7–6.7) decreased to 3 (IQR: 1–5) in the recurrent samples (p<0.001). Patients infected with a single haplotype on day 0 had no recrudescence; the risk of recrudescence increased by 28% with each additional haplotype (HR: 1.3, 95%CI: 1.24–1.44).

Conclusion

The PCR-corrected efficacy of ASAQ at day 42 was 92.8%, but crude efficacy was relatively poor due to high reinfection rates. Treatment outcomes were positively correlated with MOI. Continued monitoring of the efficacy of ACTs—ASAQ, in this case—is paramount.

Trial Registration

ClinicalTrials.gov NCT01374581

In Vivo Efficacy of Artesunate/Sulphadoxine-Pyrimethamine versus Artesunate/Amodiaquine in the Treatment of Uncomplicated P. falciparium Malaria in Children around the Slope of Mount Cameroon: A Randomized Controlled Trial

Background: The development and spread of antimalarial drug resistant parasites contributes to the global impact of the disease. In vivo efficacy assessments of treatments for Plasmodium falciparum malaria are essential for ensuring effective case management. Artemisinin-based combinations have been adopted as the first-line treatment for uncomplicated P. falciparum malaria in Cameroon since 2004. Methods: A total of 177 children aged six-months to 10 years with uncomplicated mono-infected falciparum malaria were randomized (1:1) to receive artesunate/sulphadoxine-pyrimethamine (AS/SP) or artesunate/amodiaquine (AS/AQ) pediatric tablets and followed up for 28 days according to the standard World Health Organization in vivo drug efficacy monitoring protocol. The primary and secondary endpoints were PCR uncorrected and corrected cure rates, as measured by adequate clinical and parasitological response (ACPR) on day 28. Results: The PCR corrected cure rate was high, overall (88.1%, 95% CI 83.1–93.1), 85.9% (95% CI 78.2–93.6), and 90.2% (95% CI 83.8–96.6) for AS/SP and AS/AQ, respectively. Twenty-one treatment failures were observed during follow-up, constituting one (4.6%), 14 (8.2%), and six (3.5%) early treatment failure (ETF), late clinical failure (LCF), and late parasitological failure (LPF), respectively. The drugs were well tolerated with no serious adverse events. Conclusions: Both AS/SP and AS/AQ are highly effective and well-tolerated treatments for uncomplicated P. falciparum malaria around the slope of Mount Cameroon.

Clinical determinants of early parasitological response to ACTs in African patients with uncomplicated falciparum malaria: a literature review and meta-analysis of individual patient data

BACKGROUND

Artemisinin-resistant Plasmodium falciparum has emerged in the Greater Mekong sub-region and poses a major global public health threat. Slow parasite clearance is a key clinical manifestation of reduced susceptibility to artemisinin. This study was designed to establish the baseline values for clearance in patients from Sub-Saharan African countries with uncomplicated malaria treated with artemisinin-based combination therapies (ACTs).

METHODS

A literature review in PubMed was conducted in March 2013 to identify all prospective clinical trials (uncontrolled trials, controlled trials and randomized controlled trials), including ACTs conducted in Sub-Saharan Africa, between 1960 and 2012. Individual patient data from these studies were shared with the WorldWide Antimalarial Resistance Network (WWARN) and pooled using an a priori statistical analytical plan. Factors affecting early parasitological response were investigated using logistic regression with study sites fitted as a random effect. The risk of bias in included studies was evaluated based on study design, methodology and missing data.

RESULTS

In total, 29,493 patients from 84 clinical trials were included in the analysis, treated with artemether-lumefantrine (n = 13,664), artesunate-amodiaquine (n = 11,337) and dihydroartemisinin-piperaquine (n = 4,492). The overall parasite clearance rate was rapid. The parasite positivity rate (PPR) decreased from 59.7 % (95 % CI: 54.5-64.9) on day 1 to 6.7 % (95 % CI: 4.8-8.7) on day 2 and 0.9 % (95 % CI: 0.5-1.2) on day 3. The 95th percentile of observed day 3 PPR was 5.3 %. Independent risk factors predictive of day 3 positivity were: high baseline parasitaemia (adjusted odds ratio (AOR) = 1.16 (95 % CI: 1.08-1.25); per 2-fold increase in parasite density, P <0.001); fever (>37.5 °C) (AOR = 1.50 (95 % CI: 1.06-2.13), P = 0.022); severe anaemia (AOR = 2.04 (95 % CI: 1.21-3.44), P = 0.008); areas of low/moderate transmission setting (AOR = 2.71 (95 % CI: 1.38-5.36), P = 0.004); and treatment with the loose formulation of artesunate-amodiaquine (AOR = 2.27 (95 % CI: 1.14-4.51), P = 0.020, compared to dihydroartemisinin-piperaquine).

CONCLUSIONS

The three ACTs assessed in this analysis continue to achieve rapid early parasitological clearance across the sites assessed in Sub-Saharan Africa. A threshold of 5 % day 3 parasite positivity from a minimum sample size of 50 patients provides a more sensitive benchmark in Sub-Saharan Africa compared to the current recommended threshold of 10 % to trigger further investigation of artemisinin susceptibility.

Maximizing antimalarial efficacy and the importance of dosing strategies

Artemisinin-based combination therapies (ACTs) are the cornerstone for the treatment of malaria. However, confirmed resistance to artemisinins in South-East Asia, and reports of reduced efficacy of ACTs raise major concerns for malaria treatment and control. Without new drugs to replace artemisinins, it is essential to define dosing strategies that maximize therapeutic efficacy, limit the spread of resistance, and preserve the clinical value of ACTs. It is important to determine the extent to which reduced efficacy of ACTs reflects true resistance versus sub-optimal dosing, and quantify other factors that determine treatment failure. Pooled analyses of individual patient data from multiple clinical trials, by investigators in the Worldwide Antimalarial Resistance Network, have shown high overall efficacy for three widely used ACTs, artemether-lumefantrine, artesunate-amodiaquine, and dihydroartemisinin-piperaquine. Analyses also highlight that suboptimal dosing leads to increased risk of treatment failure, especially among children. In the most recent study, an analysis of clinical trials of artesunate-amodiaquine, widely used among children in Africa, revealed a superior efficacy for fixed-dose combination tablets compared to loose non-fixed dose combinations. This highlights the benefits of fixed-dose combinations as a practical strategy for ensuring optimal antimalarial dosing and maximizing efficacy. Please see related article: http://www.biomedcentral.com/1741-7015/13/66.

Drying anti-malarial drugs in vitro tests to outsource SYBR green assays

BACKGROUND

Measurement of anti-malarial drug efficacy and resistance relies mainly on in vivo clinical trials, in vitro/ex vivo assays and molecular markers detection. The existing in vitro/ex vivo assays, in particular those that are using non-radioactive devices, need to be standardized and adapted to field conditions. SYBR Green assay offers a rapid and cheap alternative to other in vitro assays, but it requires tools not commonly available in field laboratories. Here is described a modified SYBR green I protocol to perform the parasite growth test with blood samples in endemic areas, followed later by the SYBR green fluorescence assay performed at a specialized laboratory level.

METHODS

In vitro susceptibility of Plasmodium falciparum clones HB3, 3D7, W2 and 7G8 to chloroquine (CQ), dihydroartemisinin (DHA), pyronaridine (PYD) and piperaquine (PPQ) was tested. Fresh isolates of P. falciparum from imported malaria cases were collected for ex vivo assays. The parasite suspension was added in 96-well plates predosed with anti-malarial drugs and incubated for 72 hours at 37°C, 5% CO2. SYBR green I protocol was modified to dry the plates after freeze-thawed process to mimic storage and shipping conditions. The plates were rehydrated with 200 μl of complete RPMI medium for fluorescence assay.

RESULTS

There were no significant differences in IC₅₀ values of CQ, DHA, PYD and PPQ, determined by the modified protocol, compared to standard protocol. Longer storage did not affect the IC₅₀ values.

CONCLUSION

The SYBR green I modified protocol produced reliable results and could be a suitable method for in vitro/ex vivo assays in field.