Therapeutic efficacy of artemether-lumefantrine for the treatment of uncomplicated falciparum malaria in northwest Benin

Therapeutic efficacy of artemether-lumefantrine, artesunate-amodiaquine and dihydroartemisinin-piperaquine in the treatment of uncomplicated Plasmodium falciparum malaria in Sub-Saharan Africa: A systematic review and meta-analysis

Background

Sub-Saharan Africa has the highest burden of malaria in the world. Artemisinin-based combination therapies (ACTs) have been the cornerstone in the efforts to reduce the global burden of malaria. In the effort to facilitate early detection of resistance for artemisinin derivatives and partner drugs, WHO recommends monitoring of ACT’s efficacy in the malaria endemic countries. The present systematic meta-analysis study summarises the evidence of therapeutic efficacy of the commonly used artemisinin-based combinations for the treatment of uncomplicated P. falciparum malaria in Sub-Saharan Africa after more than a decade since the introduction of the drugs.

Methods

Fifty two studies carried out from 2010 to 2020 on the efficacy of artemether-lumefantrine or dihydro-artemisinin piperaquine or artesunate amodiaquine in patients with uncomplicated P. falciparum malaria in Sub-Saharan Africa were searched for using the Google Scholar, Cochrane Central Register of controlled trials (CENTRAL), PubMed, Medline, LILACS, and EMBASE online data bases. Data was extracted by two independent reviewers. Random analysis effect was performed in STATA 13. Heterogeneity was established using I² statistics.

Results

Based on per protocol analysis, unadjusted cure rates in malaria infected patients treated with artemether-lumefantrine (ALU), artesunate-amodiaquine (ASAQ) and dihydroartemisinin-piperaquine (DHP) were 89%, 94% and 91% respectively. However, the cure rates after PCR correction were 98% for ALU, 99% for ASAQ and 99% for DHP.

Conclusion

The present meta-analysis reports the overall high malaria treatment success for artemether-lumefantrine, artesunate-amodiaquine and dihydroartemisinin-piperaquine above the WHO threshold value in Sub-Saharan Africa.

Human leukocyte antigen (HLA)-F and -G gene polymorphisms and haplotypes are associated with malaria susceptibility in the Beninese Toffin children

BACKGROUND

Little attention has been devoted to the role of the immunoregulatory HLA-E/-F/-G genes in malaria. We evaluated the entire HLA-E/-F/-G variability in Beninese children highly exposed to Plasmodium falciparum (P.f.) malaria.

METHODS

154 unrelated children were followed-up for six months and evaluated for the presence and number of malaria episodes. HLA-E/-F/-G genes were genotyped using massively parallel sequencing. Anti P.f. antibodies were evaluated using ELISA.

RESULTS

Children carrying the G allele at HLA-F (-1499,rs183540921) showed increased P.f. asymptomatic/symptomatic ratio, suggesting that these children experienced more asymptomatic P.f. episodes than symptomatic one. Children carrying HLA-G-UTR-03 haplotype exhibited increased risk for symptomatic P.f. episodes and showed lower IgG2 response against P.f. GLURP-R2 when compared to the non-carriers. No associations were observed for the HLA-E gene.

CONCLUSION

HLA-F associations may be related to the differential expression profiles of the encoded immunomodulatory molecules, and the regulatory sites at the HLA-G 3'UTR may be associated to posttranscriptional regulation of HLA-G and to host humoral response against P.f.

Therapeutic Efficacy of Artemether-Lumefantrine (Coartem®) for the Treatment of Uncomplicated Falciparum Malaria in Africa: A Systematic Review

Background

Africa still bears the largest burden of malaria as the majority of infections in the continent are caused by P. falciparum. Artemether-lumefantrine (AL, Coartem®) is the most widely used artemisinin-based combination therapy (ACT), for treating uncomplicated falciparum malaria globally. However, the development of resistance to antimalarial drugs is a major challenge for malaria control. In this review, the efficacy of AL for the treatment of uncomplicated falciparum malaria in Africa was evaluated.

Methods

Articles published between January 2015 and July 2019 were systematically searched using comprehensive search strings from PubMed/Medline, SCOPUS, and grey literature from Google Scholar. Interventional studies that followed patients for at least 28 days were included. Two reviewers independently assessed study eligibility, extracted data, and assessed risk of bias. All the included articles were measured to be good quality. While computing the efficacy of AL, polymerase chain reaction (PCR)–corrected cure rate (adequate clinical and parasitological response, ACPR) at day 28 was considered as the main endpoint. Meta-analysis was computed using STATA v 15 to calculate the pooled ACPR.

Results

In this review, 39 articles that reported the treatment outcome of 8,320 patients were included. After 28 days of follow-up, the pooled PCR uncorrected and corrected APCR was at 87% (95% CI: 85-90%) and 97.0% (95% CI: 96-98%), respectively. Moreover, the proportion of early treatment failure (ETF) was almost 0%, while most of the included articles reported <8% late treatment failures. The reinfection and recrudescence rate was less than 10% and 2.6%, respectively, within 28 days. We noted rapid fever and parasite clearance in which greater than 93% and 94% patients were parasite and fever free at day three following AL treatment.

Conclusions

This review discovered that despite more than a decade since its introduction, Coartem® remains effective and thus could continue to be the drug of choice for the treatment of uncomplicated falciparum malaria for all age groups in Africa. However, the risk of new emerging resistance for this combination warrants regular monitoring of its efficacy across the continent.

Therapeutic Efficacy of Artemether-Lumefantrine for Uncomplicated Falciparum Malaria in Northern Zambia

Artemether-lumefantrine (AL) is a first-line agent for uncomplicated malaria caused by Plasmodium falciparum. The WHO recommends periodic therapeutic efficacy studies of antimalarial drugs for the detection of malaria parasite drug resistance and to inform national malaria treatment policies. We conducted a therapeutic efficacy study of AL in a high malaria transmission region of northern Zambia from December 2014 to July 2015. One hundred children of ages 6 to 59 months presenting to a rural health clinic with uncomplicated falciparum malaria were admitted for treatment with AL (standard 6-dose regimen) and followed weekly for 5 weeks. Parasite counts were taken every 6 hours during treatment to assess parasite clearance. Recurrent episodes during follow-up (n = 14) were genotyped to distinguish recrudescence from reinfection and to identify drug resistance single nucleotide polymorphisms (SNPs) and multidrug resistance protein 1 (mdr1) copy number variation. Day 7 lumefantrine concentrations were measured for correspondence with posttreatment reinfection. All children who completed the parasite clearance portion of the study (n = 94) were microscopy-negative by 72 hours. The median parasite elimination half-life was 2.7 hours (interquartile range: 2.1-3.3). Genotype-corrected therapeutic efficacy was 98.8% (95% CI: 97.6-100). Purported artemisinin and lumefantrine drug resistance SNPs in atp6, 3D7_1451200, and mdr1 were detected but did not correlate with parasite recurrence, nor did day 7 lumefantrine concentrations. In summary, AL was highly effective for the treatment of uncomplicated falciparum malaria in northern Zambia during the study period. The high incidence of recurrent parasitemia was consistent with reinfection due to high, perennial malaria transmission.

Surveillance of the Efficacy of Artemisinin-Piperaquine in the Treatment of Uncomplicated Plasmodium falciparum Malaria Among Children Under 5 Years of Age in Est-Mono District, Togo, in 2017

BACKGROUND

Malaria is a major public health concern in Togo. The Est-Mono district of Togo has a population of 150,000. Accordingly, the Guangzhou University of Chinese Medicine, China and the Ministry of Health and Social Security, Togo launched a nationwide Mass Drug Administration Project with artemisinin-piperaquine (AP) in Est-Mono. Before launching this project, the sensitivity test of AP was conducted in a general clinic in Elawagnon, Togo. With this background, we evaluated the efficacy and safety of AP for the treatment of uncomplicated falciparum malaria in children under the age of 5 years.

METHODS

Children aged 6-59 months with uncomplicated falciparum malaria were enrolled in this study. The selected patients were treated with a combination regime of artemisinin-piperaquine. The patients were followed up for 28 days, during which signs of the following were observed for: the duration for fever clearance, parasitemia density, gametophyte generation, cure rate, hemoglobin level, and merozoite surface protein-2 (msp-2) polymorphism. The primary end point was a 28-day cure rate and polymerase chain reaction (PCR)-corrected reinfection and recrudescence. This research followed the standardized World Health Organization (WHO) protocol for the assessment of the efficacy of antimalarial drugs.

RESULTS

A total of 91 children with uncomplicated falciparum malaria were enrolled in this study. Adequate clinical and parasitological responses (ACPRs) before and after PCR-correction were 66 (73%) and 90 (99%), respectively. The average hemoglobin level in the patient increased by 0.05 g/dl per day (p < 0.0001) after the treatment. The gametophyte generation did not decline at the beginning of the treatment; however, after 14 days, it declined (day 21: p < 0.05; day 28: p < 0.01). In the msp-2 polymorphism study of 24 children treated for parasite infection, one case of msp-2 with 3D7 haplotype and FC27 haplotype was noted, indicating its recrudescence, with a frequency of 4%. The remaining 23 cases could have been of reinfection, with a frequency of 96%. No serious adverse reactions occurred, and AP was well-tolerated by all patients.

CONCLUSION

Artemisinin-piperaquine was found to be an effective combination for treating uncomplicated falciparum malaria in children aged <5 years in Togo, and the drugs were well-tolerated. In Togo, Plasmodium falciparum remains sensitive to artemisinin-piperaquine, necessitating its trial in this region.

CLINICAL TRIAL REGISTRATION

Trial registration: ECGPHCM No. B2017-054-01; MHSST AVIS N° 0001/2016/CBRS du 07 janvier 2016. Registered 17 March 2014, http://www.chinadrugtrials.org.cn/eap/main.

Ex vivo efficacy of selective chalcone derivatives on reference strains and field isolates of Plasmodium falciparum

The extension of Plasmodium falciparum resistance to existing antimalarial drugs is worrying. Faced with this problem, the search for new and effective molecules is necessary. In this context, six chalcone derivatives (B1, B11, B14, B17, SCA02 and SCA03) were tested on field isolates and then reference strains to evaluate their antiplasmodial activity by using the Rieckmann semi-microtest, recommended by WHO, for in vitro and ex vivo activity tests. Compounds B14 and B17 exhibited promising antiplasmodial activities (IC_50s: 14.41-16.40 μM) regardless of the type of isolate. Compounds B1, B11, SCA02 and SCA03 showed a moderate inhibition of field isolates (IC_50S: 25.63-48.29 μM) and very good activity against reference strains (IC50s: 3.82-10.03 μM). Therefore, more structural modulations should improve their efficiency and make these molecules very good candidates for future effective antimalarial drugs.

Improving Methods for Analyzing Antimalarial Drug Efficacy Trials: Molecular Correction Based on Length-Polymorphic Markers msp-1, msp-2, and glurp

Drug efficacy trials monitor the continued efficacy of front-line drugs against falciparum malaria. Overestimating efficacy results in a country retaining a failing drug as first-line treatment with associated increases in morbidity and mortality, while underestimating drug effectiveness leads to removal of an effective treatment with substantial practical and economic implications.

Drug efficacy trials monitor the continued efficacy of front-line drugs against falciparum malaria. Overestimating efficacy results in a country retaining a failing drug as first-line treatment with associated increases in morbidity and mortality, while underestimating drug effectiveness leads to removal of an effective treatment with substantial practical and economic implications. Trials are challenging: they require long durations of follow-up to detect drug failures, and patients are frequently reinfected during that period. Molecular correction based on parasite genotypes distinguishes reinfections from drug failures to ensure the accuracy of failure rate estimates. Several molecular correction “algorithms” have been proposed, but which is most accurate and/or robust remains unknown. We used pharmacological modeling to simulate parasite dynamics and genetic signals that occur in patients enrolled in malaria drug clinical trials. We compared estimates of treatment failure obtained from a selection of proposed molecular correction algorithms against the known “true” failure rate in the model. Our findings are as follows. (i) Molecular correction is essential to avoid substantial overestimates of drug failure rates. (ii) The current WHO-recommended algorithm consistently underestimates the true failure rate. (iii) Newly proposed algorithms produce more accurate failure rate estimates; the most accurate algorithm depends on the choice of drug, trial follow-up length, and transmission intensity. (iv) Long durations of patient follow-up may be counterproductive; large numbers of new infections accumulate and may be misclassified, overestimating drug failure rate. (v) Our model was highly consistent with existing in vivo data. The current WHO-recommended method for molecular correction and analysis of clinical trials should be reevaluated and updated.

High therapeutic efficacy of artemether-lumefantrine and dihydroartemisinin-piperaquine for the treatment of uncomplicated falciparum malaria in Somalia

Background

Artemether–lumefantrine (AL) and dihydroartemisinin–piperaquine (DHA/PPQ) are the recommended first- and second-line treatments, respectively, for uncomplicated falciparum malaria in Somalia. The studies reported here were conducted to assess the efficacy of these artemisinin-based combinations and the mutations in Plasmodium falciparum K13-propeller (Pfk13) domain and amplification in Pfplasmepsin 2 (Pfpm2) gene in Somalia.

Methods

One-arm prospective studies were conducted to assess the clinical and parasitological responses to DHA/PPQ and AL at two sites in 2016 and 2017, respectively, using the standard WHO protocol. The patterns of molecular markers associated with artemisinin and PPQ resistance were investigated for the first time in Somalia.

Results

A total of 339 patients were enrolled with 139 for AL and 200 for DHA/PPQ. With AL, no parasite recurrence was observed among patients treated at either site, corresponding to 100% clinical and parasitological responses. For DHA–PPQ, an adequate clinical and parasitological response rate > 97% was observed. All study patients on both treatments at both sites were parasite-free on day 3. Of the 138 samples with interpretable results for the polymorphism in Pfk13, only one (0.7%), from Bosaso, contained a non-synonymous mutation (R622I), which is not one of the known markers of artemisinin resistance. No Pfpm2 amplification was observed among the 135 samples with interpretable results.

Conclusions

AL and DHA/PPQ were highly effective in the treatment of uncomplicated falciparum malaria, and there was no evidence of resistance to artemisinin or PPQ. These two combinations are thus relevant in the chemotherapeutic strategy for malaria control in Somalia.

Trial registration ACTRN12616001005448 (Jowhar DP study), ACTRN12616000553471 (Bosaso DP study), ACTRN12617001055392 (AL study in Bosaso and Jowhar)

Efficacy of artemisinin-based combination therapies and prevalence of molecular markers associated with artemisinin, piperaquine and sulfadoxine-pyrimethamine resistance in Sierra Leone

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The evaluated artemisinin combination therapies were highly efficacious for the treatment of uncomplicated malaria.

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Pfk13 mutations and Pfplasmepsin2 multiple copies, associated with artemisinin and piperaquine resistance, respectively, were absent.

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The very low prevalence of the quintuple mutant detected supports the introduction of intermittent preventive treatment for infants with SP.

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The efficacy and molecular markers of the recommended artemisinins and partners drugs should be monitored continuously.

Currently, the national malaria control programme (NMCP) of Sierra Leone recommends artesunate–amodiaquine (ASAQ) and artemether–lumefantrine (AL) as first- and second-line treatment for uncomplicated malaria, respectively, and artesunate + sulfadoxine–pyrimethamine (SP) for intermittent preventive treatment during pregnancy and for infants. In 2016, the NMCP conducted a study to assess the clinical and parasitological responses of children under five years to ASAQ, AL and dihydroartemisinin–piperaquine (DHA/PPQ) according to the WHO protocol. Day-0 samples were tested for mutations in the Kelch 13 gene (pfk13) and dihydrofolate reductase/dihydropteroate synthase (pfdhfr/pfdhps) genes associated with artemisinin and SP resistance, respectively, and amplification in the pfplasmepsin2 gene for piperaquine resistance. A total of 295 (ASAQ = 128, AL = 64 and DHA/PPQ = 103) eligible children were enrolled at three sites. PCR-corrected 100% adequate clinical and parasitological response and no parasitaemia on day-3 were observed for all patients in each treatment group. Of the 278 samples with interpretable molecular data, only 2.2% carried non-synonymous pfk13 mutants (A578S, I646T), which are not associated with artemisinin resistance. None of the 103 day-0 samples from the DAH/PPQ group had pfplasmepsin2 gene amplification, confirming the absence of piperaquine resistance. The prevalence of the triple pfdhfr mutant (N51I/C59R/S108N) was close to or reached fixation (97.4–100%). For combined pfdhfr/pfdhps mutation, 55–71% carried the quadruple (N51I/C59R/S108N+A437G) mutant and about 10% the quintuple mutant N51I/C59R/S108N+A437G/K540E. Our findings confirm that ASAQ, AL and DHA/PPQ were highly effective for the treatment of uncomplicated malaria in the study areas, and neither pfk13 validated mutations nor pfplasmepsin2 multiple copies were found. The very low prevalence of the quintuple mutant in this study supports the NMCP’s decision to introduce intermittent preventive treatment for infants with SP in the districts with high malaria transmission.

High efficacy of artemether-lumefantrine and dihydroartemisinin-piperaquine for the treatment of uncomplicated falciparum malaria in Muheza and Kigoma Districts, Tanzania

BACKGROUND

Artemether-lumefantrine (AL) is the recommended first-line artemisinin-based combination therapy (ACT) for the treatment of uncomplicated falciparum malaria in most of the malaria-endemic countries, including Tanzania. Recently, dihydroartemisinin-piperaquine (DP) has been recommended as the alternative anti-malarial to ensure effective case management in Tanzania. This study assessed the parasite clearance rate and efficacy of AL and DP among patients aged 6 months to 10 years with uncomplicated falciparum malaria in two sites with different malaria transmission intensity.

METHODS

This was an open-label, randomized trial that was conducted at two sites of Muheza Designated District Hospital and Ujiji Health Centre in Tanga and Kigoma regions, respectively. Patients meeting inclusion criteria were enrolled, treated with either AL or DP and followed up for 28 (extended to 42) and 42 (63) days for AL and DP, respectively. Parasite clearance time was monitored in the first 72 h post treatment and the clearance rate constant and half-life were calculated using an established parasite clearance estimator. The primary outcome was parasitological cure on days 28 and 42 for AL and DP, respectively, while secondary outcome was extended parasitological cure on days 42 and 63 for AL and DP, respectively.

RESULTS

Of the 509 children enrolled (192 at Muheza and 317 at Ujiji), there was no early treatment failure and PCR uncorrected cure rates on day 28 in the AL group were 77.2 and 71.2% at Muheza and Ujiji, respectively. In the DP arm, the PCR uncorrected cure rate on day 42 was 73.6% at Muheza and 72.5% at Ujiji. With extended follow-up (to day 42 for AL and 63 for DP) cure rates were lower at Ujiji compared to Muheza (AL: 60.2 and 46.1%, p = 0.063; DP: 57.6 and 40.3% in Muheza and Ujiji, respectively, p = 0.021). The PCR corrected cure rate ranged from 94.6 to 100% for all the treatment groups at both sites. Parasite clearance rate constant was similar in the two groups and at both sites (< 0.28/h); the slope half-life was < 3.0 h and all but only one patient cleared parasites by 72 h.

CONCLUSION

These findings confirm high efficacy of the first- and the newly recommended alternative ACT for treatments for uncomplicated falciparum malaria in Tanzania. The high parasite clearance rate suggests absence of suspected artemisinin resistance, defined as delayed parasite clearance. Trial registration This trial is registered at ClinicalTrials.gov under registration number NCT02590627.

Polymorphisms in the K13 Gene in Plasmodium falciparum from Different Malaria Transmission Areas of Kenya

The development of artemisinin (ART)-resistant parasites in Southeast Asia (SEA) threatens malaria control globally. Mutations in the Kelch 13 (K13)-propeller domain have been useful in identifying ART resistance in SEA. ART combination therapy (ACT) remains highly efficacious in the treatment of uncomplicated malaria in Sub-Saharan Africa (SSA). However, it is crucial that the efficacy of ACT is closely monitored. Toward this effort, this study profiled the prevalence of K13 nonsynonymous mutations in different malaria ecological zones of Kenya and in different time periods, before (pre) and after (post) the introduction of ACT as the first-line treatment of malaria. Nineteen nonsynonymous mutations were present in the pre-ACT samples (N = 64) compared with 22 in the post-ACT samples (N = 251). Eight of these mutations were present in both pre- and post-ACT parasites. Interestingly, seven of the shared single-nucleotide polymorphisms were at higher frequencies in the pre-ACT than the post-ACT parasites. The A578S mutation reported in SSA and the V568G mutation reported in SEA were found in both pre- and post-ACT parasites, with their frequencies declining post-ACT. D584Y and R539K mutations were found only in post-ACT parasites; changes in these codons have also been reported in SEA with different amino acids. The N585K mutation described for the first time in this study was present only in post-ACT parasites, and it was the most prevalent mutation at a frequency of 5.2%. This study showed the type, prevalence, and frequency of K13 mutations that varied based on the malaria ecological zones and also between the pre- and post-ACT time periods.

Lack of artemisinin resistance in Plasmodium falciparum in northwest Benin after 10 years of use of artemisinin-based combination therapy

AIM

In Benin, artemisinin-based combination therapy (ACT) has been recommended as the first-line treatment for uncomplicated Plasmodium falciparum malaria since 2004. The emergence in Southeast Asia of parasites that are resistant to artemisinins poses a serious threat to global control of this disease. The presence of artemisinin resistance genotypes in parasite populations in Benin is currently unknown. The present study investigated the prevalence of relevant K13-propeller gene polymorphisms in parasite isolates from the north-western region of Benin.

METHOD

Plasmodium falciparum isolates were collected from children with a confirmed diagnosis of malaria aged 6 months to 5 years in two towns, Cobly and Djougou, in the north-western part of Benin. The study was conducted during the rainy season from July to November 2014 in local health facilities. The K13-propeller gene was amplified in parasite isolates using nested PCR and subsequently sequenced.

RESULTS

A total of 108 children were recruited into the study. The efficiency of amplification reactions was 72% (78/108). The propeller domain of the K13 gene was successfully sequenced in 78 P. falciparum isolates; all of them were wild type with no polymorphisms detectable.

CONCLUSION

The absence of mutations in the K13 gene indicates that P. falciparum parasite populations in the study area are still fully susceptible to artemisinins.

Therapeutic efficacy trial of artemisinin-based combination therapy for the treatment of uncomplicated malaria and investigation of mutations in k13 propeller domain in Togo, 2012-2013

BACKGROUND

Since 2005, the Togo National Malaria Control Programme has recommended two different formulations of artemisinin-based combination therapy (ACT), artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL), for the treatment of uncomplicated malaria. Regular efficacy monitoring of these two combinations is conducted every 2 or 3 years. This paper reports the latest efficacy assessment results and the investigation of mutations in the k13 propeller domain.

METHODS

The study was conducted in 2012-2013 on three sentinel sites of Togo (Lomé, Sokodé and Niamtougou). Children aged 6-59 months, who were symptomatically infected with Plasmodium falciparum, were treated with either AL (Coartem(®), Novartis Pharma, Switzerland) or ASAQ (Co-Arsucam(®), Sanofi Aventis, France). The WHO standard protocol for anti-malarial treatment evaluation was used. The primary end-point was 28-day adequate clinical and parasitological response (ACPR), corrected to exclude reinfection using polymerase-chain reaction (PCR) genotyping.

RESULTS

A total of 523 children were included in the study. PCR-corrected ACPR was 96.3-100 % for ASAQ and 97-100 % for AL across the three study sites. Adverse events were negligible: 0-4.8 % across all sites, for both artemisinin-based combinations. Upon investigation of mutations in the k13 propeller domain, only 9 (1.8 %) mutations were reported, three in each site. All mutant parasites were cleared before day 3. All day 3 positive patients were infected with k13 wild type parasites.

CONCLUSIONS

The efficacy of AL and ASAQ remains high in Togo, and both drugs are well tolerated. ASAQ and AL would be recommended for the treatment of uncomplicated malaria in Togo.