Conceived and designed the experiments: SD PLK AP BG SW PW. Performed the experiments: ZP REU SOA FE EUE SO SB AS RG. Analyzed the data: ZP REU SOA FE EUE SO SB AS SD AP LK RG BG SW PW. Wrote the paper: ZP AP LK. Critically reviewed the paper: REU SOA FE EUE SO SB AS SD PLK RG BG SW PW. Approved the final version of the paper: ZP REU SOA FE EUE SO SB AS SD PLK AP LK RG BG SW PW.
The authors declare no conflict of interest other than P L Kirby, A Pamba and L Kellam who are employed by GlaxoSmithKline PLC and S Duparc who was employed by GlaxoSmithKline PLC at the time of the study and is now employed by the Medicines for Malaria Venture as stated in the affiliations.
Chlorproguanil−dapsone−artesunate (CDA) was developed as an affordable, simple, fixed-dose artemisinin-based combination therapy for use in Africa. This trial was a randomized parallel-group, double-blind, double-dummy study to compare CDA and artemether−lumefantrine (AL) efficacy in uncomplicated
The trial was conducted at medical centers at 11 sites in five African countries between June 2006 and August 2007. 1372 patients (≥1 to <15 years old, median age 3 years) with acute uncomplicated
Although parasitologically effective at Day 28, the hemolytic potential of CDA in G6PD-deficient patients makes it unsuitable for use in a public health setting in Africa.
ClinicalTrials.gov NCT00344006
Malaria is clearly an insupportable burden upon sub-Saharan Africa. Approximately 210−300 million clinical malaria episodes and over 1 million deaths occur in this region annually
Artemisinin-based combination therapy (ACT) is clinically effective, and may reduce malaria transmission and the potential for the development and spread of resistance
Chlorproguanil−dapsone−artesunate (CDA) was developed as an affordable, fixed-dose ACT for use in Africa. Once-daily dosing over three days and good activity of the chlorproguanil–dapsone (CPG−DDS) component suggested a promising combination
Artemether−lumefantrine (AL) is the current gold standard ACT. The six-dose regimen is highly effective and represents a challenging comparator for any new agent
The protocol for this trial and supporting CONSORT checklist are available as supporting information; see
This study was conducted in accordance with Good Clinical Practices, applicable regulatory requirements, and the Declaration of Helsinki. Approval was obtained from each participating center's ethics committee or institutional review board and the WHO Special Programme for Research and Training in Tropical Medicine. An Independent Data Monitoring Committee (IDMC) was convened and planned to conduct two interim safety analyses. The IDMC appointed an independent end-point reviewer (blinded to treatment assignment).
Male and female patients (≥1–<15 years old) who met the following criteria were eligible for enrolment: acute uncomplicated
Subjects were excluded if they had: severe/complicated
At screening, a full medical history was obtained and a clinical examination undertaken. Eligible patients were randomized (2∶1) to receive CDA (GlaxoSmithKline, Greenford, UK) 2/2.5/4 mg/kg/day once daily for three days, administered according to predefined dosing charts, or six-dose AL (Novartis Pharma AG, Basel, Switzerland). One 20/120 mg AL tablet was given for patients weighing 5–15 kg, two for 15–<25 kg, three for 25–<35 kg and four for ≥35 kg, taken at study start (Day 0), 8 h later and then twice daily for two days. AL was dosed with milk. Matching placebos were administered to maintain blinding. Administration of therapy was directly observed and if vomiting occurred within 30 mins of dosing, the patient was re-dosed. If vomiting occurred again, the patient was treated with rescue medication (as per local clinical practice guidelines) and followed until Day 42.
Patients remained hospitalized until Day 3, returning for follow-up visits on Days 7, 14, 28 and 42. Field workers visited patients at home on Days 4, 5 and 6 to ensure they remained well. Clinical evaluation and temperature recording was performed before first dose, during therapy and at all clinic follow-up visits. Subjects failing therapy at any time during the study received rescue medication immediately and were followed until Day 42 or resolution.
Venous blood samples (2 mL) were obtained for hematology assessments at screening and on Days 1, 2, 3, 7, 14, 28 and 42 and for standard clinical chemistry tests at pre-dose, on Days 3 and 42, and on Days 14 and 28 if previous assessment values were abnormal.
Asexual parasite and gametocyte counts were performed at screening, at pre-dose, every 8 h during the in-patient stay until discharge on Day 3 and at follow-up visits on Days 7, 14, 28 and 42. At each time point, two thick and one thin film were prepared and parasite densities determined by examination of a thick blood slide (10 µL thumb prick), according to WHO methods
A pre-dose blood sample (10 µL) was collected onto pre-printed filter paper for G6PD genotype analysis at two laboratories (Shoklo Malaria Research Unit, Mae Sot, Thailand and Kenya Medical Research Institute, Nairobi, Kenya). Following DNA extraction, fragment amplification using PCR primers for loci 376 A→G, 202 G→A, 542 G→T, 680 G→T and 968 T→C allowed recognition of the wildtype (G6PD B) and the common African mutations G6PD A and A–
The objective of this trial was to compare CDA and AL efficacy in uncomplicated
The primary efficacy endpoint was parasitological cure rate (PCR-corrected) at Day 28, defined as eradication of initial malaria infection by Day 7 plus aparasitemia through to Day 28. Parasitological cure was also evaluated at Days 14 and 42 as a secondary outcome.
PCR-corrected parasitological cure was the standard method for assessing antimalarial efficacy at the time that the study was designed. However, publication of the WHO 2003 guidelines for evaluating antimalarials led to the protocol being amended to include adequate clinical and parasitological response (ACPR) as a secondary outcome
Other secondary outcomes included: asexual parasite and gametocyte counts; mean parasite clearance time (time at which asexual parasites became undetectable and remained so for ≥48 h); and mean fever clearance time (time at which temperature normalized and remained so for ≥48 h).
Adverse events were defined as any unfavorable and unintended sign (including an abnormal laboratory test result), symptom, or disease (new or exacerbated) temporally associated with the use of a medicinal product. Adverse events were recorded at all clinic visits and coded using MedDRA (Version 10.1). Serious adverse events were defined as: death or life-threatening illness; resulting in hospitalization or prolongation of hospitalization; significantly disabling/incapacitating; congenital anomaly; hemoglobin decrease ≥40% versus baseline; hemoglobin <50 g/L; blood transfusion; methemoglobin ≥20% or ≥10 to <20% with associated clinical symptoms; or any other event considered significant by the investigator.
A composite ‘hemoglobin safety’ endpoint was defined prospectively as: hemoglobin decrease of ≥40 g/L or ≥40% versus baseline or hemoglobin <50 g/L or blood transfusion.
The study was designed with ≥90% power to test the hypothesis that CDA was non-inferior to AL for the primary outcome measure. Assuming efficacy of 93% for CDA and 95% for AL, 650 and 325 evaluable patients, respectively, were required using a one-sided hypothesis test at a 2.5% significance level and a 7% non-inferiority margin. Allowing for 30% loss, target recruitment was 930∶465 patients CDA:AL. No multiplicity was associated with this single primary comparison.
GlaxoSmithKline generated the randomization schedule comprising blocks of six patients by center.
Randomization was done at the study site by a telephone call to the automated Registration and Medical Ordering System (RAMOS). An individual patient's code could be accessed by an investigator via RAMOS in an emergency.
Investigators, technicians performing microbiological assessments and patients were blinded to study treatments.
The intent to treat (ITT) population included all randomized patients who received at least one dose of study medication. The PP population was a sub-set of the ITT population including patients who did not violate the protocol in a way that might impact the efficacy analysis.
The primary analysis was performed on the Day 28 PP population. The difference in PCR-adjusted parasitological cure rates and the 95% confidence interval (CI) was calculated using the normal approximation to the binomial distribution. A similar analysis was performed for the ITT population and for ITT observed cases (i.e. excluding missing data). For the PP population, a logistic regression model was fitted to estimate treatment effect adjusted for country, age (<5 years, 5–<15 years), and baseline parasitemia (categorized by ≤33%, >33–<67%, and ≥67% quantile). Descriptive statistics were provided for secondary endpoints (PP and ITT populations) and safety outcomes (ITT population).
For patients who were failures owing to new infections (determined using PCR), both PP and ITT analyses deemed these subjects to be successes at that time point. However, at subsequent time points, the PP analyses considered these patients as missing and the ITT analysis assumed that they were failures.
Patients with missing data at the relevant time point were excluded from PP analyses of efficacy data (PCR-adjusted parasitological cure and ACPR). In the ITT analyses, treatment failure was imputed for missing data. For example, a patient with no Day 28 parasite count would be excluded from the primary endpoint and ACPR PP analyses but included as a treatment failure in the supporting ITT analyses. If a patient was missing a parasite assessment before Day 28, this would not affect assessment of Day 28 parasitological cure, whereas for ACPR, treatment failure could not be assessed and the patient would be excluded from the PP analysis with an imputation of failure in the corresponding ITT analysis.
Comparisons of CDA and AL for the hemoglobin safety composite endpoint and changes in hemoglobin versus baseline were analyzed by the following G6PD genotype categories: G6PD normal, G6PD heterozygous females, and G6PD deficient (hemizygous A− males and homozygous A−/A− females). Logistic regression modeling was used to quantify the impact of G6PD genotype, weight, age, baseline hemoglobin, baseline parasitemia, and treatment on hemoglobin safety endpoints.
Participant flow is shown in
The trial was conducted between June 2006 and August 2007 at health centers in Bobo-Dioulasso, Burkina Faso; Kintampo, Ghana; Eldoret, Kilifi and Pingilikani, Kenya; Ibadan, Enugu, Jos and Calabar, Nigeria; and Bagamoyo and Kiwangwa, Tanzania.
Baseline characteristics were similar between treatment groups; all patients were of Black African ethnicity (
Characteristic | CDA (N = 914) | AL (N = 458) |
Male sex, n (%) | 457 (50) | 245 (53) |
Mean age, years (SD) [range] | 4.2 (3.0) |
4.0 (2.9) |
Number aged 1 to <5 years, n (%) | 586 (64) | 300 (66) |
Number aged 5 to <15 years, n (%) | 328 (36) | 158 (35) |
Mean weight, kg (SD) [range] | 16.2 (7.1) [8–62] | 16.0 (6.8) [8–59] |
Geometric mean parasitemia (µL−1) (range) | 23378 (0–389415) |
22383 (185–705600) |
Mean hemoglobin, g/L (SD) [range] | 100 (15) [58–145] |
100 (15) [47–158] |
Three patients in the CDA group had parasites identified at screening, were enrolled, randomized and treated, though later examination revealed that the parasites were
At some sites, screening hemoglobin level was determined using a rapid test (Haemacue, Downfield, UK), with subsequent checking using a coulter counter. Twelve subjects in the CDA group and five in the AL group had haemacue tests of ≥70 g/L with subsequent coulter counter hemoglobin values of <70 g/L. Coulter counter values are reported here.
Category | Genotype |
CDA | AL | Total |
Missing, n (%) | 69 (15) | 30 (12) | 99 (14) | |
Genotype, n (%) | 388 (85) | 215 (88) | 603 (86) | |
A | 85 (22) | 46 (21) | 131 (22) | |
B | 239 (62) | 139 (65) | 378 (63) | |
A− | 64 (16) | 30 (14) | 94 (16) | |
Missing, n (%) | 45 (10) | 27 (13) | 72 (11) | |
Genotype, n (%) | 412 (90) | 186 (87) | 598 (89) | |
A/A | 16 (4) | 13 (7) | 29 (5) | |
A/B | 101 (25) | 32 (17) | 133 (22) | |
B/B | 156 (38) | 92 (49) | 248 (41) | |
A/A− | 41 (10) | 13 (7) | 54 (9) | |
B/A− | 82 (20) | 30 (16) | 112 (19) | |
A−/A− | 16 (4) | 6 (3) | 22 (4) |
Percentages exclude missing data.
Day 14, there were 787/914 (86%) evaluable patients in the CDA group and 393/458 (86%) in the AL group and at Day 42 661/914 (72%) and 332/458 (72%), respectively.
Parasitological cure (PCR-corrected) at Day 28 in the PP population was 94.1% for CDA and 97.4% for AL (treatment difference −3.3%, 95%CI −5.6, −0.9;
Parasitological cure, n (%) at: | PP population | ITT population | ||
CDA (N = 796) |
AL (N = 400) |
CDA (N = 914) |
AL (N = 458) |
|
PCR corrected | 758/787 (96.3) | 376/393 (95.7) | 834 (91.2) | 415 (90.6) |
Treatment difference (95%CI) | 0.6 (−1.8, 3.0) | 0.6 (−2.6, 3.9) | ||
PCR corrected | 703/747 (94.1) | 369/379 (97.4) | 758 (82.9) | 391 (85.4) |
Treatment difference (95%CI) | −3.3 (−5.6, −0.9) | −2.4 (−6.5, 1.6) | ||
PCR corrected | 591/661 (89.4) | 311/332 (93.7) | 647 (70.8) | 336 (73.4) |
Treatment difference (95%CI) | −4.3 (−7.8, −0·7) | −2.6 (−7.6, 2.4) |
In the PP analysis, patients with missing data were excluded and patients with new infections (determined by PCR) were considered successes at the first time point that this outcome was recorded, but were excluded thereafter.
At Day 14, nine patients were non-evaluable in the CDA group: two earlier new infections (0.25%), three without PCR at Day 14, and four for ‘other’ reasons. In the AL group, seven patients were non-evaluable: one earlier new infection (0.25%), five without PCR at Day 14, and one ‘other’.
At Day 28, 49 patients were non-evaluable in the CDA group: 26 earlier new infections (3.3%), ten without PCR at Day 28, and 13 ‘other’. In the AL group, 21 patients were non-evaluable: ten earlier new infections (2.5%), seven without PCR at Day 28, and four ‘other’.
At Day 42, 135 patients were non-evaluable in the CDA group: 109 earlier new infections (13.7%), ten without PCR at Day 42, and 16 ‘other’. In the AL group, 68 patients were non-evaluable: 56 earlier new infections (14.0%), five without PCR at Day 42, and seven ‘other’.
In the ITT analysis, patients with missing data were treated as failures. Patients with new infections (determined by PCR) were considered successes at the first time point that this outcome was recorded and as failures thereafter.
Non-inferiority was maintained in the ITT analysis (
For parasitological secondary endpoints (
This study was not powered to compare treatments for individual countries. Per-country Day 28 cure rates (PP population) were as follows: Ghana/Burkina Faso, CDA 95.7% (110/115), AL 98.3% (58/59), treatment difference −2.7%, 95%CI −7.6, 2.3; Kenya, CDA 95.5% (150/157), AL 97.5% (77/79), treatment difference −1.9%, 95%CI −6.7, 2.8; Nigeria, CDA 94.1% (272/289), AL 98.0% (148/151), treatment difference −3.9%, 95%CI −7.4, −0.4); Tanzania, CDA 91.9% (171/186), AL 95.6% (86/90), treatment difference −3.6%, 95%CI −9.4, 2.2.
ACPR at Day 28 in the PP population was 79% for CDA and 83% for AL; ACPRp was 93% and 94%, respectively (
Treatment response, n/N (%) at: | PP population | ITT population | ||
CDA (N = 796) |
AL (N = 400) |
CDA (N = 914) | AL (N = 458) | |
Early treatment failure |
8/760 (1) | 6/381 (2) | 65 (7) | 37 (8) |
Late clinical failure | 41 (5) | 16 (4) | 40 (4) | 17 (4) |
Late parasitological failure | 112 (14) | 44 (11) | 122 (13) | 49 (11) |
ACPR | 604/765 (79) | 315/381 (83) | 687 (75) | 355 (78) |
ACPRp |
708/765 (93) | 360/381 (94) | 791 (87) | 403 (88) |
Late clinical failure | 69 (9) | 28 (7) | 66 (7) | 28 (6) |
Late parasitological failure | 167 (21) | 75 (19) | 179 (20) | 82 (18) |
ACPR | 527/771 (68) | 275/384 (72) | 604 (66) | 311 (68) |
ACPRp |
697/771 (90) | 358/384 (93) | 774 (85) | 398 (87) |
For the PP population, patients with missing data or indeterminate results were excluded − the denominator shows the number of evaluable patients. For the ITT population, patients with missing or indeterminate PCR results were treated as failures. For ACPRp, in the PP and ITT analysis, patients with new infections were considered successes at that time point. However, at subsequent time points, the PP analyses considered these patients as missing and the ITT analysis assumed that they were failures.
Early treatment failure is the same for Day 42.
ACPRp is ACPR corrected using PCR genotyping for reinfection. Reinfection rate = ACPRp − ACPR.
Asexual parasite counts decreased rapidly in both treatment groups; by 16 h post first treatment dose, parasite counts had declined by 99% in both groups. Mean (SD) parasite clearance time was 23.5 (11.0) h (N = 909) for CDA and 26.2 (11.5) h (N = 456) for AL (ITT population). For patients with baseline fever, mean fever clearance time (SD) was: 28.7 (23.3) h (N = 538) and 26.6 (22.2) h (N = 250) (ITT population).
Gametocytes were present at baseline in 25/912 (3%) patients in the CDA group and in 10/458 (2%) in the AL group (ITT population). The proportion of gametoyctemic patients decreased throughout the study similarly in both treatment groups. For both the PP and ITT population analyses, the geometric means ranged between 1.0 and 1.1 parasites/µL throughout the study in both treatment groups. The median gametocyte counts were 0 prior to dosing and at each time point following dosing for both treatment groups.
A subject was considered compliant with study treatment if they received the treatment to which they were randomized as well as the correct dose for their body weight on all three dosing days. Compliance with study medication was 94% for both treatment groups.
The proportion of treatment-emergent adverse events due to any cause was similar between the treatment groups: 476/914 (52%) in the CDA group and 220/458 (48%) in the AL group. The majority of adverse events were mild to moderate in intensity (96% for CDA, 98% for AL). Adverse events reported by investigators as probably or possibly drug-related occurred in 184 (20%) patients in the CDA group and 86 (19%) in the AL group (
Preferred term, n (%) | CDA (N = 914) | AL (N = 458) |
Reticulocyte count decreased | 79 (9) | 44 (10) |
Anemia | 24 (3) | 9 (2) |
Hemoglobin decreased | 24 (3) | 7 (2) |
Vomiting | 14 (2) | 4 (<1) |
Thrombocytopenia | 15 (2) | 3 (<1) |
Patients with at least one drug-related adverse event | 184 (20) | 86 (19) |
Serious adverse events were reported for 63/914 (7%) patients in the CDA and 15/458 (3%) patients in the AL group. In the CDA group, serious adverse events most likely related to oxidative hemolysis occurred in 46/914 (5%) of patients versus 3/458 (<1%) in the AL group. In G6PD-deficient patients receiving CDA, 26/80 (33%) had such events (six cases of hemoglobin decreased, seven hematuria/hemoglobinuria [these were not always differentiated], two hemolysis, two hemolytic anemia and one blood methemoglobin) compared with 10/597 (2%) for G6PD normal (seven anemia, two hemoglobin decreased, one intravascular hemolysis) and 5/123 (4%) for female heterozygotes (two anemia, three hemoglobin decreased). In the AL group, malaria was the most common serious adverse event (7/458 [2%]). All serious adverse events in the AL group were in G6PD-normal patients, except one case of malaria in a heterozygous female.
Overall in the ITT population, mean hemoglobin concentrations decreased versus baseline from Day 1 for both treatment groups (
Day 0 are screening (baseline) values.
The proportion of patients with a decrease in hemoglobin concentration versus baseline of ≥20 g/L was 305/914 (33%) with CDA and 112/458 (24%) with AL. By G6PD genotype, this endpoint occurred in 173/597 (29%) normal, 45/123 (37%) heterozygote and 45/80 (56%) deficient patients in the CDA group and in 77/322 (24%), 9/43 (21%) and 12/36 (33%), respectively in the AL group.
Occurrences of the hemoglobin safety endpoint in G6PD-deficient patients were 35% (28/80) with CDA versus 0% with AL (
G6PD genotype, n/N (%) | CDA | AL |
Normal | 18/597 (3) | 5/322 (2) |
Female heterozygous | 7/123 (6) | 1/43 (2) |
G6PD deficient |
28/80 (35) | 0/36 |
Missing | 11/114 (10) | 3/57 (5) |
64/914 (7) | 9/458 (2) |
Deficient is male hemizygous G6PD A− and female homozygous G6PD A–/A−.
Fourteen blood transfusions were performed for a significant decrease in hemoglobin, all in the CDA group: 12 in G6PD-deficient patients, one in a heterozygous female, and one in a G6PD-normal patient. One subject in the CDA group received a transfusion for treatment of sickle cell crisis (G6PD status unknown). A further subject in the CDA group (hemizygous male) was hospitalized on Day 6 requiring a blood transfusion (hemoglobin 38 g/L), though blood was not available. This patient subsequently recovered under close observation and supportive treatment with hematinics.
Three deaths occurred during the study: two in the CDA and one in the AL group; none were attributed to study treatment by the investigator. In the CDA group, a 2-year-old female had severe malaria and severe herbal intoxication at Day 23 and 24 and died on Day 24; a 4-year-old male with sickle cell anemia with crisis and severe sepsis was inadvertently recruited into the study, withdrawn on Day 1 and transfused and died on Day 2. In the AL group, a 1-year-old male had severe pyrexia at Day 26 and died on Day 29. There were three other withdrawals because of adverse events, two with CDA (vomiting and febrile convulsion) and one with AL (hematuria), all of which resolved.
For the primary endpoint of this trial, parasitological cure at Day 28 (PP population), CDA was highly efficacious (94%). CDA was non-inferior to AL, but AL was simultaneously superior to CDA. An adjusted logistic regression analysis (PP population) also showed AL superiority. Non-inferiority of CDA to AL for the primary efficacy endpoint was not maintained at Day 42. These results confirm the high efficacy of AL in Africa
It was notable that there was no difference in reinfection rates between the two treatment groups. A recent comparison of CDA and AL also found no difference in reinfection rates
Although this study was designed primarily to assess efficacy, the most clinically important findings relate to safety, specifically G6PD-related hemolysis in the CDA group. The 2∶1 CDA:AL randomization schedule was chosen to provide adequate data for a meaningful analysis of CDA safety. Also, we defined a composite hemoglobin safety endpoint based on laboratory data for hemoglobin declines of clinical concern and blood transfusion events. Overall, the main risk factors associated with the composite endpoint were G6PD deficiency versus G6PD normal (OR 16.3, 95%CI 8.6, 31.2) and CDA treatment versus AL (OR 5.1, 95%CI 2.1, 12.4). In G6PD-deficient patients (hemizygous males and homozygous females), 35% met the composite endpoint criteria with CDA versus none with AL. Of particular concern was that 12/15 patients requiring blood transfusion were G6PD-deficient, and all in the CDA group.
This study was not powered to detect a difference in hematological safety in G6PD-deficient patients between treatment groups. However, subjects meeting the composite hemoglobin safety endpoint would clearly require hospital-based interventions. These are often difficult to access for the majority of malaria patients in sub-Saharan Africa. Based on the composite endpoint data, CDA has an unacceptable risk:benefit profile versus AL for the treatment of malaria in G6PD-deficient patients. Consequently, this population should not be exposed to CDA.
The prevalence of G6PD deficiency in this study was 16% hemizygous males and 4% homozygous females; a substantial sub-population. The lowest prevalence of G6PD deficiency was 7.7% in Ibadan, though this is considerably lower than previous estimates, generally in excess of 20%
G6PD phenotyping and genotyping are not generally available in Africa. Even if G6PD-deficient patients could be excluded, post-hoc regression analysis found that in G6PD-normal patients, the risk of a ≥20 g/L hemoglobin decrease versus baseline was slightly increased with CDA versus AL (OR 1.4, 95%CI 1.01, 1.96). The clinical relevance of this small difference is debatable, but further undermines CDA utility, given the availability of alternative agents. CDA was developed for use in Africa as a safe, affordable, effective and simple antimalarial. As these conditions cannot be met, the Joint Development Team decided to terminate CDA development and withdraw CPG−DDS licenses.
Although we knew that there would be some hemolytic effect of dapsone, the magnitude of the difference in this effect between CDA and AL in G6PD-deficient patients was unexpected
In this study, comparison of the timecourse for hemoglobin decline with CDA and AL is instructive (
Dapsone had been used in malaria and leprosy for many years with no major safety concerns
In the CPG−DDS safety study by Alloueche
The position becomes even more complicated when the limited analysis of hemoglobin declines by G6PD genotype in the Alloueche
A recently published study conducted in Rwanda comparing CDA versus amodiaquine (AQ) plus SP for the treatment of uncomplicated malaria is also informative
One important question is whether the hemolysis observed here is new to CDA or would have been seen with CPG−DDS versus AL. Preliminary results from a second Phase III clinical trial of similar design indicate no major differences in hematological safety between CDA and CPG−DDS (personal communication P. Winstanley).
There were some limitations in the hematological data collected in this study. A validated methemoglobin test, suitable for clinic use, was only available towards the end of the study. Consequently, only 32 patients from two centers (Eldoret and Calabar) had screening and post-baseline methemoglobin data. Collection of reticulocyte data was not automated and there was no quality control process. On examination, reticulocyte percent and absolute data could not be interpreted and the results are not presented. G6PD phenotypic data were only available for 632/1372 (46%) patients because of logistical problems in transporting samples to a central laboratory within a narrow time window and data are not presented. The difficulties in obtaining sufficient G6PD phenotype data quickly hampered assessment of safety within the G6PD-deficient population by the IDMC during the recruitment phase. For the limited data available, concordance of a G6PD-deficient phenotype with genotype in hemizygous males was 271/313 (87%), and phenotype findings supported genotype findings with respect to both G6PD-deficiency prevalence and hemoglobin safety.
To our knowledge, this is the first randomized controlled clinical Phase III multi-centre study to include a component investigating the relationship between hematological safety and G6PD deficiency. There is no accepted in vitro test or in vivo model to determine the potential for G6PD-related hemolysis. G6PD genotyping and separate analysis of hemizygous males/homozygous females versus heterozygote females and G6PD-normal patients was necessary to show the clinical importance of the interaction between CDA and G6PD deficiency for hematological safety. Our results highlight that new antimalarials, such as AL, may have significant safety as well as efficacy benefits over older therapies, illustrating the need to conduct comprehensive Phase III trials of antimalarial combination therapies against relevant comparators, even when the components are already approved individually. It also highlights the challenges of developing therapies for populations harboring G6PD deficiency and possibly other polymorphisms.
CONSORT checklist
(0.07 MB DOC)
Trial Protocol
(0.44 MB PDF)
The authors are grateful to Professor Lucio Luzzatto for his review of the manuscript and helpful comments. Naomi Richardson of Magenta Communications Ltd developed a first draft of this paper from the approved study report and collated author contributions and was funded by GlaxoSmithKline PLC. The authors would like to thank all those who were involved in the clinical trial teams at Bobo-Dioulasso in Burkina Faso, Kintampo in Ghana, Eldoret, Kilifi and Pingilikani in Kenya, Ibadan, Enugu, Jos and Calabar in Nigeria, and Bagamoyo and Kiwangwa in Tanzania. The investigators would also like to gratefully acknowledge the children and their parents who agreed to take part in this study. Steffen Borrmann is supported by a Deutsche Forschungsgemeinschaft (DFG) Junior Group grant (SFB 544, A7).
Contributors
The study team also consisted of the following co-investigators: Dr Halidou Tinto and Dr Augustin Zeba (Bobo-Dioulasso, Burkina Faso); Ms Livesy Abokyi and Dr Kwaku Poku Asante (Kintampo, Ghana); Dr Samuel Ayaya and Dr Naftali Busakhala (Eldoret, Kenya); Mr Ken Awuondo and Mr Harald Kirr (Kilifi and Pingilikani, Kenya); Dr Grace O Gbotosho and Dr Felix O Akinbami (Ibadan, Nigeria); Dr Tagbo Oguonu and Dr Elvis Shu (Enugu, Nigeria); Dr Innocent C Omalu and Mark T Akindigh (Jos, Nigeria); Professor Martin M Meremikwu and Dr Friday A Odey (Calabar, Nigeria); Dr Vera Juma and Mr Chris Membi (Bagamoyo and Kiwangwa, Tanzania).