Efficacy and safety of fixed dose combination of arterolane maleate and piperaquine phosphate dispersible tablets in paediatric patients with acute uncomplicated Plasmodium falciparum malaria: a phase II, multicentric, open-label study

This phase II, multicentric, open-label study of 42 days’ duration was carried out between July 2010 to November 2012 at six sites across India and Africa. The patients were recruited from three hospitals each in India (Ispat General Hospital, Rourkela, Orissa; Tata Main Hospital, Jamshedpur, Jharkhand; and, Mahadevi Birla Hospital and Research Centre, Ranchi, Jharkhand) and Africa (General Hospital of Ayame, Ivory Coast; North Abobo General Hospital, Ivory Coast; and, Ruhuha Health Centre, Bugesera District, Rwanda).

Children of either gender aged between 6 months and 12 years who presented with clinical symptoms of malaria were screened for study eligibility after assent was obtained from the patient (where possible) or informed consent from parents/guardians. Children with microscopically confirmed acute uncomplicated falciparum malaria, with parasite density ranging from 1000 to 100,000 asexual parasites/μL (both inclusive) and an axillary temperature ≥37.5 °C or history of fever in the past 24 h, were included in the study. Additional inclusion criteria were minimum body weight of 5 kg; ability to take drugs under study by the oral route, absence of severe malnutrition (defined as a child whose weight-for-height is below −3 standard deviation or less than 70 % of the median of the NCHS/WHO normalized reference values or who had symmetrical oedema involving at least the feet, minimum haemoglobin level ≥8 g/dL; and, willingness and ability to comply with the study protocol for the duration of the study; residence within a reasonable distance of the investigational site so that attendance of all study visits and follow-up by medical staff were logistically feasible.

Exclusion criteria included mixed Plasmodium infection; severe malaria; presence of general danger signs of severe malaria among children <5 years old (as per WHO); infants with a history of hyperbilirubinaemia during the neonatal period; pregnant and lactating females (between the age of 8 and 12 years); ongoing prophylaxis with drugs having anti-malarial activity, such as cotrimoxazole, for the prevention of Pneumocystis carinii pneumonia in children born to HIV + women; any anti-malarial treatment during 1 month prior to screening; use of concomitant medications that could induce haemolysis or haemolytic anaemia from the WHO list of essential drugs; known allergy to artesunate, artemether, artemisinin-derived products, piperaquine phosphate or any other related drug; and, participation in any investigational drug study during 30 days prior to screening. Patients with electrocardiogram (ECG) abnormalities with clinical significance or relevance that required urgent management were excluded from the study. These abnormalities included QTc interval >450 ms at screening and cardiac conduction disorders, with the exception of right bundle branch block. Patients with known significant renal or hepatic impairment indicated by the following laboratory evaluations at screening: serum creatinine >1.5 × upper limit of normal (ULN), aspartate transaminase >2.5 × ULN, alanine transaminase >2.5 × ULN and serum bilirubin >3 mg/dL; patients who have had a splenectomy; known history of HIV infection or other immunosuppressive disorders; evidence of clinically significant cardiovascular, pulmonary, metabolic, gastrointestinal, neurological, or endocrine diseases, malignancy, or other abnormalities; history of epilepsy/convulsions; evidence of gastrointestinal dysfunction that could alter absorption or motility (e.g., diarrhoea defined as >3 episodes of watery stools in the previous 24 h or patients who have had three episodes of vomiting within 24 h prior to screening); any other underlying disease that could compromise the diagnosis and the evaluation of the response to the study medication (including clinical symptoms of immunosuppression, tuberculosis, bacterial infection, cardiac or pulmonary disease) were also excluded from the study.

The study was conducted as per the study protocol that was reviewed and approved by the Institutional Ethics Committees/Institutional Review Boards of the participating study sites and regulatory authorities. This clinical study was conducted in accordance with the Good Clinical Practice, applicable regulatory requirements, and Declaration of Helsinki. Written informed consent was obtained from all parents/guardians of the patients. Assent was acquired from children wherever it was applicable. This study is registered with Clinical Trial Registry India (CTRI/2009/091/000531).

Patients were administered FDC of arterolane maleate 37.5 mg and piperaquine phosphate 187.5 mg dispersible tablets as single daily doses for three consecutive days based on their age (age group I, 6 months to <2 years: one tablet; age group II, 2 to <6 years: two tablets; and, age group III, 6 to ≤12 years: 3 tablets) by the qualified staff under supervision. Each tablet was dissolved in 10 mL of drinking water with continuous swirling. The study medication was administered irrespective of meals. If a patient vomited or regurgitated (for small children) within 1 h of receiving any dose of investigational product on any of the dosing days, the patient was administered a second full dose (repeat dose). If the patient vomited again within 30 min of receiving the repeat dose, the patient was withdrawn from the study and given rescue treatment. Re-dosing in case of vomiting was allowed only once during the study.

Initial screening was offered to patients who presented with fever or history of fever and eligible patients were hospitalized for a treatment period of 3 days (day 0, 1 and 2: day 0 being the first day of study medication dosing). Patients were discharged on day 3 and follow-up assessments were done on weekly intervals up to day 42.

Physical examination, vital signs, body temperature, and clinical assessment were done at screening, on therapy and at all follow-up visits. Body temperature was recorded at 6 h intervals (or adjusted to the closest possible 6 h interval to make the schedule consistent with routine care) following the first dose of study medication until temperature normalized and remained normal for 24 h, and at every visit thereafter. A 12-lead electrocardiograph was performed on screening day 0, 1, 2, and on any unscheduled day if patient reported with fever and at follow up visits if ECG was abnormal.

Laboratory evaluations (haematology, biochemistry and urinalysis) were performed during study and at follow-up visits. Clinically significant laboratory abnormalities on any visit were repeated during the next follow-up visit or earlier, if clinically indicated. Adverse events were reported for the time of study medication administration and at all follow-up visits.

Thick/thin blood smears were collected at the time of screening, pre-dose at day 0 and at 6 h intervals (or adjusted to the closest possible 6 h interval to make the schedule consistent with routine care) following first dose of administration until two consecutive negative smears were recorded, thereafter at day 3 and follow-up visits.

Filter paper samples for molecular marker studies [polymerase chain reaction (PCR) genotyping] were collected on screening and in the event of re-appearance of parasites, confirmed by microscopy, or on any other day if a patient returned with fever. PCR analysis was done at a central laboratory.

Venous blood samples were collected from each enrolled patient for pharmacokinetic analysis of arterolane maleate and piperaquine phosphate. The compounds were measured by LC–MS/MS methods validated as per US FDA Guidance for Industry: bioanalytical method validation, May 2001 [12]. An analysis was performed in compliance with Good Laboratory Practice regulations.

The study was conducted according to WHO guidelines [13]. The primary efficacy outcome was proportion of patients with PCR-corrected adequate clinical and parasitological response (ACPR) on day 28. PCR-corrected ACPR was defined as patients who had clearance of parasitaemia, irrespective of axillary temperature, without previously meeting any of the criteria of early treatment failure (ETF) or late clinical failure (LCF) or late parasitological failure (LPF). Secondary efficacy outcomes included parasite clearance time (PCT), defined as time in hours from the initiation of therapy until the first of two successive negative smears are obtained; fever clearance time (FCT) defined as the time from first dosing until temperature normalizes (<37.5 °C) and remains normal for 24 h, and at every follow up visit thereafter; proportion of patients with PCR-uncorrected ACPR on day 28; proportion of patients with PCR-corrected and PCR-uncorrected ACPR on day 42 and the number of gametocytes count. Safety endpoints were adverse events or clinically significant changes in laboratory parameters, physical examination, ECG or vital signs.

To have 100 evaluable patients in this study, 120 patients were planned to be enrolled, assuming an expected treatment failure rate of 4 % (supported by another in-house phase II study, cure rate of ~96 %), a 5 % level of significance and a precision of ±4 % [10]. This was done to ensure that the 95 % (exact binomial) confidence interval of cure rate would be between 90 and 99 %, well within the expected range. Additional 20 % patients were accounted for the dropouts during the study. However, while conducting the study in India, dropout rate of ~30 % was experienced on account of vomiting. Therefore, enrolment of additional patients was allowed at these sites to ensure availability of adequate evaluable data. Accordingly, a total of 141 patients were enrolled in the study.

The primary efficacy analysis was based on per-protocol population (PCR-corrected ACPR at day 28). The per-protocol population included all patients who completed a full course of study medication with a known efficacy endpoint and who did not violate the protocol in a way that might affect the efficacy analysis, i.e., the use of prohibited concomitant medication, the presence of significant disease or co-morbid illness, or major protocol violation. Intent-to-treat (ITT) and survival analyses were considered supportive. All the secondary endpoint (ACPR uncorrected at day 28, ACPR uncorrected/corrected at day 42, PCT, and FCT) analyses were done on ITT population, which included all patients who received at least one dose of study medication.

The proportion of patients having PCR-corrected ACPR at day 28 was estimated using 95 % exact (Clopper-Pearson) binomial confidence interval. The proportion of patients with PCR-uncorrected ACPR on day 28 and PCR-uncorrected ACPR at day 42 were analyzed similar to the primary endpoint. Time-to-event parameters (PCT and FCT) were assessed using survival analysis (Kaplan–Meier method). Patients with early withdrawal or those in whom parasite was not cleared or had fever at 72 h were censored at day 7 (168 h), i.e., next follow-up visit. These patients were considered failures in ITT analysis. Gametocyte counts at different visits were summarized using descriptive statistics, along with proportion of patients with zero gametocyte. Demographic and other baseline characteristics were summarized descriptively using mean, standard deviation, range, and count (%).

The safety population was defined as all patients who received any amount of study medication and had at least one assessment after dosing. The safety analyses included incidences of adverse events, summary statistics of laboratory data and ECG findings. All the analyses were performed using SAS software version 9.1.3 (SAS Institute, Cary, NC, USA) at 5 % two-sided level.