P. Knowlesi Trial of Artesunate-mefloquine Versus Chloroquine (ACT KNOW)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT01708876
Recruitment Status : Completed
First Posted : October 17, 2012
Last Update Posted : April 9, 2015
Ministry of Health, Malaysia
Information provided by (Responsible Party):
Menzies School of Health Research

Brief Summary:

Preliminary studies have supported the background efficacy of local standard anti-malarial medications in the treatment of uncomplicated knowlesi malaria, however this has not been tested systematically and there are no current WHO treatment guidelines for this infection. There are both health cost benefits to a more rapidly acting agent, and due to difficulties with microscopic identification there may be more effective treatment for all malaria species if an aligned treatment guideline could be supported. In addition, no therapeutic efficacy monitoring of current first line anti-malarials used for the treatment of P. vivax malaria have been conducted in Malaysia.

The investigators aim to test whether the fixed combination of artesunate-mefloquine is superior to chloroquine in order to define the optimal treatment for both uncomplicated P. knowlesi and P. vivax infection in both adults and children in this region.

Condition or disease Intervention/treatment Phase
Uncomplicated Plasmodium Knowlesi Malaria Drug: Artesunate-mefloquine Drug: Chloroquine Drug: Primaquine Phase 3

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Detailed Description:

1.1 Background

Naturally acquired infections with Plasmodium knowlesi, the fifth human malaria, are growing [1]. Since 2004 increasing numbers of cases have been reported from residents and returned travelers predominantly from Malaysia and other countries in South-East Asia including Thailand, Vietnam, Myanmar, Singapore, Indonesia and the Philippines [2-8]. Cases coincide with the geographic distribution of its natural simian hosts (long-tailed and pig-tailed macaques) and Anopheles leucosphyrus group mosquito vector [9, 10], with potential human-to-human transmission unknown. Eastern Malaysia appears to be the epicentre, with around 1400 PCR-confirmed P. knowlesi human mono-infections reported in 2009, comprising 41% of 2,189 total malaria cases in Sarawak [11] and 343 cases from selected samples sent to Sabah's State Reference Laboratory [12]. P. knowlesi is also now the most common cause of malaria in different contrasting regions, including 70% of malaria admissions in the heavily forested area of Kapit in Sarawak [1, 13], 63% of samples from the interior division of Sabah [14], and in 87% of malaria admissions in the deforested coastal area of Kudat in Sabah, where it is also the major cause of malaria in children [15].

Despite the increase in reported incidence, difficulties with microscopic diagnosis and a lack of PCR based epidemiological surveillance studies throughout South-East Asia mean the true disease burden is underestimated. P. knowlesi is microscopically misidentified as P . falciparum and P. malariae due to morphological similarities in the early trophozoite, and late trophozoite and schizont life stages respectively, with studies showing up to 80% of P. malariae [16-19] and 7-12% of P. falciparum [1, 16] in this region are actually P. knowlesi when definitively evaluated with PCR. Current rapid diagnostic tests (RDT) for malaria can distinguish falciparum Current rapid diagnostic tests (RDT) for malaria can distinguish falciparum from other Plasmodium species with a sensitivity of up to 99% at parasite counts > 1,000/ μL [20], but a knowlesi specific antigen has not been developed and current antibody panels are unable to differentiate between P. knowlesi and other mixed Plasmodium spp. infections [21]. Misdiagnosis has concerning treatment implications, as unlike P. malariae, knowlesi malaria has a rapid 24-hour replication rate and can cause hyperparasitaemia, severe complications and fatal outcomes [13, 17, 18], while the inadvertent use of chloroquine for widely chloroquine-resistant P. falciparum may also have fatal consequences.

1.2 Treatment

Initial observational and retrospective studies have suggested both chloroquine and artemisinin combination therapy (ACT) are effective therapy for uncomplicated P. knowlesi infection [15, 16, 22, 23]. Justification for treatment selection for this trial is based on this literature review. Case reports predominantly from returned travelers to South-East Asia also document uncomplicated knowlesi malaria responding well to conventional anti-malarials such as chloroquine, mefloquine, atovaquone with proguanil, doxycycline and quinine [4, 24- 31], supporting its zoonotic and drug naïve origin. However to date there have been no prospective randomised trials to compare chloroquine and ACT as the anti-malarials currently used for uncomplicated P. knowlesi infection in Malaysia, and there are no current recommendations on how to treat P. knowlesi infection in the WHO 2010 malaria treatment guidelines. As ACTs are already being used for treating P. falciparum and are recommended for the increasingly chloroquine-resistant P. vivax found in the surrounding countries in South East Asia [32], the potential benefit of a unified treatment policy to facilitate prompt and effective treatment of all Plasmodium species needs evidence of ACT as the optimal treatment for P. knowlesi infection also.

Malaysian Ministry of Health guidelines currently recommend chloroquine and primaquine as first line treatment for the erythrocytic and hypnozoite life stages of uncomplicated P. vivax malaria respectively. While resistance to chloroquine has previously been documented in Sabah [35] and Peninsular Malaysia [36-38], the unstable transmission dynamics and recent reduction in P. vivax incidence due to public health measures mean the current risk of chloroquine-resistant P.vivax transmission is likely to be low. Despite this, due to increasing resistance in surrounding countries including Indonesia, Thailand, Vietnam, and PNG [39], transient populations of migrant workers, and recent concerns of the failing efficacy of hypnozoite eradication by primaquine [40], the need for ongoing therapeutic efficacy monitoring is recommended [41].

1.3 Artesunate-mefloquine

Artesunate-mefloquine (AS-MQ) is a common and widely available ACT, and along with artemether-lumefantrine (A-L) is one of only 2 first line WHO recommended options for the treatment of uncomplicated P. falciparum infection which are registered in Malaysia and produced according to international good manufacturing practice (GMP) standards. ACTs are the current mainstay of malaria elimination efforts [33], with a mechanism of action resulting both in a rapid reduction in parasite mass and resolution of clinical features, while the long acting component eliminates residual parasites and delays the development of de novo resistance [34, 35]. Safety and tolerability of all ACTs are dependent on their partner drug [36], and while gastro-intestinal and self-limiting neuro-psychiatric adverse events have been reported with mefloquine, multiple safety and efficacy trials have recommended its use in both adults and children for uncomplicated falciparum malaria [37-40]. Due to concerns over the safety of mefloquine in the first trimester of pregnancy [41], and its use in patients with pre-existing psychiatric disorders or those who have previously had cerebral malaria, it is currently not advised for these groups [36].

The only reported use of ACT for knowlesi malaria is from our retrospective study at a tertiary referral hospital in Sabah, where a small sample size of 8 out of 34 patients with PCR- confirmed uncomplicated P. knowlesi infection were treated with oral artemether- lumefantrine. Median microscopic parasite clearance time was 1 day (range 0-3), which was significantly faster than those receiving chloroquine (median 2.5 days, range 1-3, p = 0.01) [23]. There are no published reports of other ACTs used in the treatment of P. knowlesi infection, although currently both AS-MQ and A-L are being used in Sabah for uncomplicated P. knowlesi and P. falciparum malaria, including in children >5kg, as recommended by local guidelines.

Mefloquine as a single agent has also been used in the successful treatment of a Swedish traveller returning from Sarawak, Malaysia with PCR confirmed uncomplicated P. knowlesi infection in 2009 [24]. The long half life of mefloquine of around 14 days also means when used as the partner drug in an ACT for uncomplicated malaria caused by other Plasmodium species such as P. vivax, there is a significant reduction compared to A-L in the day 42 treatment failure rate [42].

1.4 Chloroquine

Chloroquine with primaquine was initially suggested to have favourable treatment outcomes for uncomplicated P. knowlesi human infections after a retrospective review of patients from Kapit Hospital in Sarawak in 2004 [16]. Following this a single prospective observational study conducted at the same site between 2006-7 administered chloroquine as a total base dose of 25mg/kg and primaquine as a gametocidal agent to 73 patients with uncomplicated PCR-confirmed P. knowlesi malaria, with results showing median fever clearance of 26 hours, mean times to 50% and 90% microscopic parasite clearance of 3.1 and 10.3 hours respectively, and a median PCR adjusted clearance time of 3 days. None of the 60 patients who completed the 28-day follow up demonstrated any evidence of resistance, re-infection or recrudescence [22].

Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 250 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: Artesunate-mefloquine vs Chloroquine in Patients With Acute Uncomplicated P. Knowlesi and P. Vivax Malaria: a Randomized Open Label Trial in Sabah, Malaysia
Study Start Date : October 2012
Actual Primary Completion Date : December 2014
Actual Study Completion Date : December 2014

Arm Intervention/treatment
Active Comparator: Artesunate-mefloquine
3 doses artesunate-mefloquine - daily over 3 days (dosage according to bodyweight - 4mg/kg and 8.3mg/kg respectively).
Drug: Artesunate-mefloquine
Other Names:
  • Artequin 600/1500
  • Artequin 300/750
  • Artequin Paed granules 50/125

Drug: Primaquine
Given to P. vivax patients only. Delayed administration at day 28; 0.5mg/kg for children or 45mg for adults; normal G6PD activity (once daily administration for 14 days); moderate G6PD deficiency (once weekly for 8 weeks); severe G6PD deficiency (contraindicated / not given).

Active Comparator: Chloroquine
4 doses chloroquine over 3 days - total dose 25mg/kg. 10mg/kg at 0 hours, 5mg/kg at 6-8, 24, 48 hours.
Drug: Chloroquine
Other Name: Chloroquine; 1 tablet = 155mg base

Drug: Primaquine
Given to P. vivax patients only. Delayed administration at day 28; 0.5mg/kg for children or 45mg for adults; normal G6PD activity (once daily administration for 14 days); moderate G6PD deficiency (once weekly for 8 weeks); severe G6PD deficiency (contraindicated / not given).

Primary Outcome Measures :
  1. Parasite clearance [ Time Frame: 24 hours ]
    The primary endpoint is the therapeutic efficacy of artesunate-mefloquine versus chloroquine, as defined by the assessment of microscopic P. knowlesi and P. vivax parasite clearance 24 hours after initiation of treatment.

Secondary Outcome Measures :
  1. Rates of recurrent infection / treatment failure at day 42. [ Time Frame: 42 days ]
  2. Occurrence of anaemia at day 28 when using AS-MQ vs. CQ. [ Time Frame: 28 days ]
  3. P. knowlesi and P. vivax gametocyte carriage throughout follow up when using AS-MQ vs. CQ. [ Time Frame: 42 days ]
  4. Frequency of complications throughout follow up when using AS-MQ vs. CQ. [ Time Frame: 42 days ]
  5. Utility of malaria rapid diagnostic tests in diagnosis of P. knowlesi infection. [ Time Frame: 1 day ]
  6. Rates of P. knowlesi and P. vivax recurrence in a 1 year follow up period. [ Time Frame: 1 year ]

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Ages Eligible for Study:   1 Year and older   (Child, Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Male and female patients at least 1 year of age and weighing more than 10kg
  • Microscopic diagnosis of Plasmodium species infection
  • Negative P. falciparum malaria rapid diagnostic test (histidine rich protein 2)
  • Fever (temperature 37.5°C) or history of fever in the last 48 hours
  • Able to participate in the trial and comply with the clinical trial protocol
  • Written informed consent to participate in trial; thumbprint is required for illiterate patients, and written consent from parents/guardian for children below age of consent

Exclusion Criteria:

  • Clinical or laboratory criteria for severe malaria, including warning signs, requiring parenteral treatment according to modified WHO criteria (see Appendix 4)
  • Parasitaemia > 20,000 /μL (P. knowlesi)
  • Inability to tolerate oral treatment
  • Concomitant infection with any other malaria species
  • Pregnancy or lactation
  • Unable or unwilling to use contraception during study period
  • Known hypersensitivity or allergy to artemisinin derivatives
  • Serious underlying disease (cardiac, renal or hepatic)
  • Received anti-malarials in last 2 months
  • Previous psychiatric illness or epilepsy
  • Previous episode of cerebral malaria

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT01708876

Kota Marudu District Hospital
Kota Marudu, Sabah, Malaysia, 89108
Kudat District Hospital
Kudat, Sabah, Malaysia, 89057
Pitas District Hospital
Pitas, Sabah, Malaysia
Sponsors and Collaborators
Menzies School of Health Research
Ministry of Health, Malaysia
Study Director: Jayaram Menon, MBBS Sabah Ministry of Health
Study Director: D Prabhakaran, MBBS Sabah Ministry of Health
Study Director: Matthew J Grigg, MBBS Menzies School of Health Research
Study Director: Tsin Yeo, MBBS Menzies School of Health Research
Study Director: Lorenz von Seidlein, MBBS Menzies School of Health Research
Study Director: Nicholas M Anstey, MBBS Menzies School of Health Research
Study Director: Ric Price, MBBS Menzies School of Health Research

Publications of Results:
Other Publications:

Publications automatically indexed to this study by Identifier (NCT Number):
Responsible Party: Menzies School of Health Research Identifier: NCT01708876     History of Changes
Other Study ID Numbers: NMRR-12-89-11005
First Posted: October 17, 2012    Key Record Dates
Last Update Posted: April 9, 2015
Last Verified: April 2015

Keywords provided by Menzies School of Health Research:

Additional relevant MeSH terms:
Protozoan Infections
Parasitic Diseases
Chloroquine diphosphate
Antiprotozoal Agents
Antiparasitic Agents
Anti-Infective Agents
Antirheumatic Agents
Anti-Inflammatory Agents, Non-Steroidal
Analgesics, Non-Narcotic
Sensory System Agents
Peripheral Nervous System Agents
Physiological Effects of Drugs
Anti-Inflammatory Agents
Antinematodal Agents