An interventional study of Tafenoquine (TQ) and Chloroquine (CQ) in Uncomplicated P. Vivax Mono-infection, sponsored by Walter Reed Army Institute of Research (WRAIR). Not yet recruiting at 1 site in Thailand. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-04-16.
Sponsored by Walter Reed Army Institute of Research (WRAIR) · Not applicable, Interventional, and Treatment
This study is to conduct a clinical trial of tafenoquine combinations to compare the rates of therapeutic efficacy of dihydroartemisinin-piperaquine or artemether-lumefantrine with tafenoquine to chloroquine plus tafenoquine in preventing recurrence of Plasmodium vivax over a 6-month period in adult subjects with uncomplicated P. vivax infection living in Thailand.
Background: There are several anti-malarials to kill P. vivax in the bloodstream and resolve the illness; however, the hallmark of P. vivax is its dormant liver-stage parasite (hypnozoite), which can reactivate months to years after the initial treatment, resulting in relapses of clinical disease. There are only two drugs that can clear hypnozoites, both of the 8-aminoquinoline (8-AQ) class: primaquine (PQ) and tafenoquine (TQ). The anti-hypnozoite mechanism(s) of action of these drugs are not entirely clear but presumably act by reactive oxygen species generated by redox cycling of the metabolites of PQ or TQ. In late 2020, a clinical trial in Indonesia (nicknamed INSPECTOR), testing TQ plus the blood stage drug, dihydroartemisinin-piperaquine (DHA-PPQ), reported 79% of participants experienced TQ drug failure which continued to have P. vivax relapses. This rate of relapse was almost the same as those participants who received no TQ (only DHA-PPQ). The dramatically lower efficacy was unexpected, the mechanisms behind these failures, unknown, and with TQ being one of the only two available medications to fully treat P. vivax infections, underscores the need to investigate the causes and find potential solutions. The best method to evaluate drug efficacy and the mechanisms underlying treatment failures is through a clinical trial. A Congressionally Directed Medical Research Program (CDMRP)-funded Clinical Trial Award project will conduct a clinical trial of tafenoquine in adults infected with P. vivax living in Thailand and fits the CDMRP Strategic Goal to develop and test more effective and shorter treatment regimens, including those that address treatment resistance. This study is supported by the U.S. DoD.
Study objective: The primary objective is to compare the rates of therapeutic efficacy of dihydroartemisinin-piperaquine or artemether-lumefantrine with tafenoquine to chloroquine plus tafenoquine in preventing recurrence of Plasmodium vivax over a 6-month period in adult subjects with uncomplicated P. vivax infection.
Study design: This clinical study designs a four arm, randomized, open-label clinical efficacy trial of adults with acute, uncomplicated mono-infection with P. vivax. At enrollment, participants will be randomized with ration 1:1:1:1.
All study participants with P. vivax infection meeting inclusion/exclusion criteria will be enrolled, treated monitored for recurrence over 6 months to determine the rate of efficacy of the four groups. After 7 days inpatient, all participants will have outpatient clinic follow-up visits at Day 14, 21, 28, 60, 90, 120, 150 and 180. Arm 4 schedule will be different a bit depend on blood and urine collection schedule.
Study population: Adult subjects, aged 18 years or older, male or non-pregnant/non-lactating female who agreed not to be pregnant, who are diagnosed with uncomplicated P. vivax mono-infection.
Number of subjects: Up to 300 volunteers will be screened to meet the goal enrollment is 200 participants (50 in each arm) to meet the primary objective and endpoint of efficacy at 180 days.
Study location: Clinical study activities will take place in Tha Song Yang district, Tak province, in western Thailand, along the Thai-Myanmar border. Another site, Sop Moei District, Mae Hong Son province, may be added if enrollment is deemed insufficient to meet target goal of 200 enrolled cases within the sponsor's specified timeline.
Timeline: The clinical study itself is expected to run for approximately 5 years to enroll and complete study procedures for all subjects. Sample and data analysis would still be conducted after clinical study closure.
123 studies on the registry are indexed under Malaria, Vivax; 19 are open to participants now.
This study's planned enrollment of 300 is above the median of 150 across 103 interventional studies indexed under Malaria, Vivax.
Browse Malaria, Vivax studies →Walter Reed Army Institute of Research (WRAIR) is the lead sponsor of 20 studies on the registry; 5 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Participants who meet all of the following criteria may participate in the study:
Exclusion Criteria:
Participants meeting any of the following criteria will be excluded from this study:
Acute or chronic, , pulmonary, cardiovascular, hepatic, neurologic, or renal functional abnormality, as determined by history, physical examination, and laboratory evaluation; specific tests for this criteria, and in the definition of severe malaria, include:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECG (electrocardiogram)
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
QT and QTc
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Bilirubin
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
TQ 300 mg once + Chloroquine (CQ), weight-based dosing for 3 days course
Drug: Tafenoquine (TQ) · Drug: Chloroquine (CQ)
TQ 300 mg once + Dihydroartemisinin-piperaquine (DHA-PPQ), weight-based dosing for 3 days course
Drug: Tafenoquine (TQ) · Drug: Dihydroartemisinin-piperaquine (DHA-PPQ)
TQ 300 mg once + Artemether-Lumefantrine (AL), weight-based dosing twice daily for the 3-day course
Drug: Tafenoquine (TQ) · Drug: Artemether-lumefantrine (AL)
DHA-PPQ weight-based dosing for the 3-day course, then pause the treatment for one day and tafenoquine 300 mg once on the 4th day.
Drug: Tafenoquine (TQ) · Drug: Dihydroartemisinin-piperaquine (DHA-PPQ)
Tafenoquine 150 mg
Also known as: KRINTAFEL
Chloroquine 150 mg base
Drug pages: Artenimol · Piperaquine
It is 40 mg DHA/320 mg PPQ
Also known as: Eurartesim
It is 20 mg of artemether and 120 mg lumefantrine
Also known as: Coartem
Estimate the rate of recurrence in all participants with uncomplicated P. vivax mono-infection in the 6 months following treatment with chloroquine, CQ, artemether-lumefantrine, AL, or dihydroartemisinin-piperaquine, DHA-PPQ, paired with tafenoquine, TQ
After discharge from hospital, outpatient follow-up visits will be scheduled at Day 14, 18 (Arm 4), 21, 25 (Arm 4), 28, 32 (Arm 4), 60, 90, 120, 150 and 180 to monitor for P. vivax recurrences.
Time frame: From enrollment to 6 months follow up
Plan to share: No — IPD data sets will not be shared as it's confidentiality of participants
No publications or documents are linked to this record.
Start is estimated for May 2026; primary completion for Oct 2028, 29 months later.
Of 14 interventional studies with no phase under Malaria, Vivax, half reached primary completion within 26 months of starting (the median), counting those still running; a quarter within 16 and three quarters within 56. This study's planned 29 months is above that.
How these figures are worked out, and which studies are left out of them.
This study is not yet recruiting, as verified in Mar 2026. You cannot join it, but the record below documents what was studied.
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Studies of the drugs tested here: Chloroquine · Artenimol · Piperaquine
Walter Reed Army Institute of Research (WRAIR)