1. Microbiology and Infectious Disease
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A randomized feasibility trial comparing four antimalarial drug regimens to induce Plasmodium falciparum gametocytemia in the controlled human malaria infection model

  1. Isaie J Reuling
  2. Lisanne A van de Schans
  3. Luc E Coffeng
  4. Kjerstin Lanke
  5. Lisette Meerstein-Kessel
  6. Wouter Graumans
  7. Geert-Jan van Gemert
  8. Karina Teelen
  9. Rianne Siebelink-Stoter
  10. Marga van de Vegte-Bolmer
  11. Quirijn de Mast
  12. André J van der Ven
  13. Karen Ivinson
  14. Cornelus C Hermsen
  15. Sake de Vlas
  16. John Bradley
  17. Katharine A Collins
  18. Christian F Ockenhouse
  19. James McCarthy
  20. Robert W Sauerwein
  21. Teun Bousema  Is a corresponding author
  1. Radboud university medical center, Netherlands
  2. Erasmus MC, University Medical Center Rotterdam, Netherlands
  3. Radboud University Medical Center, Netherlands
  4. PATH Malaria Vaccine Initiative, United States
  5. London School of Hygiene and Tropical Medicine, United Kingdom
  6. QIMR Berghofer, Australia
Research Article
Cite as: eLife 2018;7:e31549 doi: 10.7554/eLife.31549
6 figures, 4 tables, 1 data set and 8 additional files


Trial profile.

ECG = electrocardiography, BMI = body mass index, AST = aspartate aminotransferase, ALP = alkaline phosphatase

Figure 2 with 1 supplement
Asexual parasitemia and gametocytemia.

Black line represents 18S qPCR asexual parasitemia. Black dotted-line represents 18S qPCR after treatment 1. Red line represents Pfs25 qRT-PCR gametocytemia.

Figure 2—figure supplement 1
Asexual parasitemia and gametocytemia per study participant.

Black line represents 18S qPCR asexual parasitemia. Black dotted-line represents 18S qPCR after treatment 1. Red line represents Pfs25 qRT-PCR gametocytemia. Grey lines represent individual PCR curves of other participants of the same group.

Gametocyte kinetics between study arms.

(A) Percentage gametocyte carriers between study arms (B) Estimated mean area under the curve for concentration of gametocytes per arm (Bayesian framework). The shaded area of each density curve represents the middle 95% percentiles (i.e. 2.5th to 97.5th percentiles) of the estimated mean AUC for a study arm; the density curve itself spans the middle 99% percentiles of the posterior; the posterior mean is indicated by the vertical solid line within each density plot. (C) Association of area under the curves of asexual parasitemia and gametocytemia. The different plotting shapes are the individual participants per group. (D) Thin- and thick- blood smears of concentrated gametocytes after magnetic cell sorting of blood samples from two individuals from LD-PIP/SP arm.

Figure 4 with 2 supplements
Total female and male gametocyte density of all participants.

Dots represent individual gametocyte data. Circles and squares represent mean and error (SEM) of gametocytes per timepoint.

Figure 4—figure supplement 1
Female and male gametocytes per study arm.
Figure 4—figure supplement 2
Female and male gametocyte clearance dynamics per participant included in analysis.

Curves are log gametocytes/mL. Recoded days are the days of gametocyte observations from 12 days after the last detection of asexual parasites until the end of study.

Figure 5 with 2 supplements
Standard curves of qRT-PCR and qPCR.

Standard curves (Mean, SD) obtained using 10-fold dilutions of cultured gametocytes. The highest concentration was enumerated by two independent expert microscopists. The mean and standard deviation of 54, 28, 72 replicates of the standard curve during the study was determined for the Pfs 25-, PfMGET, and 18S target genes, respectively. For PfMGET, six points starting from 106 pure male gametocytes/mL were measured. 101 was positive in 6/28 replicates (black dot).

Figure 5—figure supplement 1
Standard curves of Pfs25 qRT-PCR – low-density trendlines.

Standard curves (Mean, SD) obtained using serial dilutions of cultured gametocytes including low-density trendlines to determine the limit of detection (LOD) and limit of quantification (LOQ) of the Pfs25 qRT-PCR.

Figure 5—figure supplement 2
Correlation of duplo Pfs25 qRT-PCR measurements in all study samples.

All duplo- estimation data points of the study participants as measured by Pfs25 qRT PCR. All samples with ≥5 parasites/mL were duplo positive (190/190, 100%), and showed a correlation coefficient R2 of 0.94. Variation of samples < 5 parasites/mL was considerably larger and positivity could not be reliably estimated with 35/75 (47%) of samples that were positive in at least one qRT-PCR being single positives (R2 of 0.46).

Figure 6 with 1 supplement
Adverse events.

(A) Adverse events per study arm (B) Total no. of adverse events and time course.

Figure 6—figure supplement 1
Liver function test derangements.

ALT = alanine aminotransferase, AST = aspartate aminotransferase, γGT = gamma glutamyl transferase, ALP = alkaline phosphatase, T1 = Treatment 1, T2 = Treatment 2.



Table 1
Baseline characteristics of the participants included in analysis.
No. subjectsn = 4n = 4n = 4n = 4
Treatment 1 (T1)Sulfadoxine-pyrimethamine 500 mg/25 mgSulfadoxine-pyrimethamine 500 mg/25 mgPiperaquine 480 mgPiperaquine 480 mg
Treatment 2 (T2)Sulfadoxine-pyrimethamine 1000 mg/50 mgPiperaquine 960 mgPiperaquine 960 mgSulfadoxine-pyrimethamine 1000 mg/50 mg
Malen (%)2 (50%)0 (0%)1 (25%)1 (25%)
Femalen (%)2 (50%)4 (100%)3 (75%)3 (75%)
AgeMean (range)24.5 (21–29)24 (21–28)21.5 (20–24)22.5 (20–27)
BMI (kg/m2)Mean (range)21 (18–23)22 (19–25)24.5 (21–27)26.5 (24–29)
Table 2
Treatment and parasitological data per study group.
Time to T1 (days)Median (range)13 (9.3–12.8)10.8
Time between T1-T2 (days)Median (range)9.1
10 (9.2–10.2)4.7 (2–10.7)2.5
Area under the curve (AUC)*Median (range)
 Asexual6490 (1120–16337)13280 (2773–43777)14347 (5408–24898)12747 (4572–82973)
 Sexual280 (27–3640)271 (64–848)784 (316–1274)6624 (1515–10244)
Peak parasite density (Pf/mL)Median (range)6467 (1050–20261)16376 (2590–50210)11603 (2408–21565)8491 (3976–63113)
Peak gametocyte density (gct/mL)Median (range)38 (11–368)30 (13–101)83 (46–99)627 (199–1285)
Day of gametocyte detection after infection (days)Mean (SD)18.3 (1.0)18.5 (1.0)17.3 (1.5)19.4 (1.3)
Time to gametocyte detection relative to first asexual parasites (days)Mean (SD)10.5 (1.3)11.5 (1.0)10.1 (1.3)10.1 (1.2)
Proportion of days gametocyte positive (%)Mean (SD)27.4 (6.7)35.9 (7.6)51.4 (7.9)48.3 (8.1)
Duration gametocytemia§ (days)Median (range)7.5 (1–24)6 (2–14)17 (12–25)24.5 (17–25)
  1. *The area under the curve (AUC) represents the total parasite exposure over time (asexual- or sexual parasite load).

    Time to gametocyte detection is calculated as the day of the detection of gametocytes (≥5 gct/mL) minus the day of first peak asexual parsitaemia.

  2. The proportion of gametocyte positive days is calculated as all days with ≥5 gct/mL by Pfs25-qRT-PCR divided by all days where Pfs25 qRT-PCR was performed.

    §Maximum number of consecutive days of Pfs25 qRT-PCR measured gametocytemia ≥5 gct/mL.

Table 3
List of adverse events possibly or probably related to the trial.
Number of subjectsNumber of subjectsNumber of episodesMean duration in days (SD)Number of subjectsNumber of episodesMean duration in days (SD)Number of subjectsNumber of episodesMean duration in days (SD)Number of subjectsNumber of episodesMean duration in days (SD)
Fatigue, Malaise164103.6 (4.5)4152.0 (3.0)4102.9 (1.1)466.8 (8.1)
Headache153121.0 (1.5)4251.2 (1.2)4171.3 (1.2)4211.6 (1.4))
Fever15490.4 (0.4)4100.3 (0.4)3110.4 (0.3)4130.7 (0.4)
Nausea144120.6 (0.8)4151.1 (1.6)381.2 (1.5)3100.7 (1.0)
Chills14341.7 (1.0))351.7 (2.0)4101.2 (1.3)460.9 (1.1)
Myalgia11353.2 (3.3)392.1 (1.9)351.2 (1.0)232.2 (2.6)
Abdominal pain10250.3 (0.2)330.6 (0.9)281.1 (1.3)331.6 (2.4)
Pruritis6230.6 (0.8)223.3 (0.5)120.3 (0.4)113.6
Athralgia5112.2241.5 (1.8)0--225.1 (3.6)
Diarrhoea5110.8110.1221.7 (2.1)114
Diziness3110.10--250.5 (0.7)0--
Reflux20--222.9 (1.8)0--0--
Aspecific chest pain1120.0 (0.0)0--0--0--
Mouth ulcera11110.00--0--0--
Grade 3 adverse events
Headache80--220.3 (0.2)220.6 (0.1)441.1 (1.3)
Chills6110.9221.7 (2.0)220.3 (0.3)112.2
Nausea5110.1230.3 (0.6)110.7110
Fever40--0--250.5 (0.4)250.7 (0.5)
Fatigue, malaise40--340.8 (0.4)1120--
Abdominal pain1110.50--0--0--
Table 4
Laboratory abnormalities per study arm.
N (% of total) of grade 1N (% of total) of grade 2N (% of total) of grade 3N (% of total) of grade 1N (% of total) of grade 2N (% of total) of grade 3N (% of total) of grade 1N (% of total) of grade 2N (% of total) of grade 3N (% of total) of grade 1N (% of total) of grade 2N (% of total) of grade 3
Any lab. abnormality15 (14)7 (7)2 (2)13 (12)10 (93 (3)16 (15)9 (8)2 (2)13 (12)8 (8)8 (8)
Decreased hemoglobin0001 (14)2 (29)01 (14)1 (14)01 (14)1 (14)0
Decreased WBC1 (8)3 (23)01 (8)2 (15)01 (8)2 (15)01 (8)2 (15)0
Decreased neutrophils3 (23)1 (8)02 (15)003 (23)1 (8)03 (23)00
Decreased lymphocytes3 (20)1 (7)01 (7)3 (20)03 (20)1 (7)01 (7)2 (13)0
Decreased platelets3 (25)002 (17)004 (33)001 (8)2 (17)0
Elevated ALT2 (13)1 (6)1 (6)2 (13)02 (13)1 (6)2 (13)1 (6)004 (25)
Elevated AST1 (7)1 (7)1 (7)2 (13)1 (7)1 (7)1 (7)2 (13)1 (7)004 (27)
Elevated yGT1 (11)001 (11)1 (11)02 (22)003 (33)1 (11)0
Elevated ALP00001 (33)00002 (67)00
Elevated total bilirubin1 (50)000000001*(50)00
Elevated creatinine0001 (100)00000000
Elevated BUN000000000000
  1. Number of subjects with the highest grade reported for a laboratory abnormality. Grading based on WHO toxicity grading scale. No grade four abnormalities were reported. Lymphocytes (109/l) were graded based on grade 1: 0.9–0.6; grade 2: 0.3–0.5; grade 3:<0.3.

    Liver function tests were graded based on grade 1: 1.1.–2.5X ULN, grade 2: 2.6–5.0x ULN, grade 3:>5.0X ULN. WBC, white blood count; ALT, alanine aminotransferase; AST, aspartate aminotransferase; yGT, glutamyl transpeptidase; ALP, alkaline phosphatase;

  2. See Figure 6—figure supplement 1 for a detailed overview of liver function test abnormalities.

    BUN, blood urea nitrogen. T1, treatment 1; T2, treatment 2.*Subject showed elevated total bilirubin at baseline.

Data availability

The following data sets were generated
  1. 1

Additional files

Source code 1

R codes used for Bayesian statistical analysis.

Source code 2

SAS code used for estimation of gametocyte half-life for gametocytes.

Supplementary file 1

Individual data of the participants included in analysis.

Supplementary file 2

Selected P. falciparum gene targets and primers of qRT PCR assays.

Supplementary file 3

Quality parameters of qRT PCR and qPCR.

The table shows for each target: limit of detection (LOD; defined as lowest pathogen concentration with reproducible detection); limit of quantification (LOQ; defined as lowest pathogen concentration where the CV was <5%), slope, efficiency (E), and the coefficient of correlation of combined trendlines (R2).

Supplementary file 4

Clinical trial protocol.

Reporting Standards 1

CONSORT extension for Pilot and Feasibility Trials Checklist.

Transparent reporting form

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