A Phase 4 interventional study of Tafenoquine prophylaxis in Prophylaxis, sponsored by Naval Medical Research Center. Status unknown at 1 site in Vietnam. Open to participants aged 18 Years to 55 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2022-04-11.
Sponsored by Naval Medical Research Center · Phase 4, Interventional, and Prevention
In 2018, the U.S. Food and Drug Administration (FDA) and the Australian Therapeutic Goods Administration (TGA) approved tafenoquine for malaria prevention. The approved tafenoquine prophylactic regimen is 600 mg loading dose (200 mg daily for 3 days) prior to travel and a weekly 200 mg maintenance dose commencing 7 days after the last loading dose. This weekly tafenoquine regimen is more convenient with potentially improved compliance than daily doxycycline or atovaquone proguanil (Malarone), the other recommended prophylactic agents by the U.S. Centers for Disease Control and Prevention (CDC) for the prevention of malaria infections.
Current assumptions are that a systemic minimum inhibitory concentration (MIC) of tafenoquine in plasma is 80 ng/mL in nonimmune individuals is required to prevent symptomatic breakthroughs of malaria infections. Because of tafenoquine's lengthy blood elimination half-life of 2-3 weeks, a monthly regimen of 600 mg and 800 mg of tafenoquine in individuals weighing 60 kg and 80 kg, respectively, have pharmacokinetic (PK) profiles (i.e., drug concentration versus time curves) of achieving MIC values of at least 80 ng/mL in the majority of healthy individuals. The aim of this study is to determine whether the safety and tolerability profiles in healthy participants taking monthly doses of 600 mg or 800 mg tafenoquine are comparable in the same participants taking weekly 200 mg tafenoquine.
Study Hypothesis: The study hypothesis is that the frequency of tafenoquine-related safety (e.g. blood chemistries) and adverse events (AEs) in healthy participants who take a higher dose (600 mg and 800 mg) of tafenoquine monthly would be comparable to the frequency of treatment related safety and AEs in the same individuals who take weekly tafenoquine (200 mg).
This is an open-label study to evaluate the safety, tolerability and PK of tafenoquine after weekly and two monthly doses of tafenoquine in healthy participants. The study will be conducted in three parts with 200 participants invited to participate in the study.
The 200 healthy participants will be divided into two cohorts (A and B) of 100 participants to fully cover the three tafenoquine regimens (i.e. weekly, low monthly and high monthly) in obtaining study information (e.g. AEs) and biospecimens for monitoring the safety, tolerability and PK of tafenoquine.
Tafenoquine: Arakoda™ tablets (each containing 100 mg of tafenoquine base) are dark pink, capsule shaped, debossed with "TQ100" on one side and plain on the other. Arakoda™ tablets are supplied in blister packs. Each blister pack contains 8 tablets. Monthly tafenoquine will be administered as 100 mg oral tafenoquine tablets (Arakoda™) identical to those marketed for weekly prophylaxis.
Objectives: Primary Objective: In a dose escalating study in the same healthy participants compare the frequency of treatment-related safety and adverse events (AEs) after weekly 200 mg tafenoquine and two monthly (600 mg and 800 mg) tafenoquine regimens.
Secondary Objectives:
Study Population: Two hundred healthy participants are planned to be enrolled in this study for Parts 1 to 3. It is planned to recruit 200 participants from 108 Military Central Hospital.
The healthy participants will be judged to be in good health based on medical history, physical examination, blood chemistries, urinalysis, serology, normal electrocardiogram (ECG), glucose-6-phosphate dehydrogenase (G6PD) normal, and free of infectious diseases, psychiatric concerns, allergies and other medical conditions that the Investigator deems may compromise the potential participant's safety and wellbeing.
Naval Medical Research Center is the lead sponsor of 2 studies on the registry; none are open to participants now.
Counted across the registry records on this site, refreshed daily.
Vital signs at screening and throughout the study (measured after five minutes in the supine position) within the following ranges:
A female participant of childbearing potential is eligible to enter the study if she is non-pregnant, non-lactating, has a negative pregnancy test at the screening visit and agrees to comply with one of the following contraceptive procedures during the study and for a period of 90 days after the last dose of tafenoquine.
Male participants who have, or may have, female sexual partner(s) during the course of the study must agree to one of the following acceptable double methods of contraception:
Exclusion Criteria:
Resting vital signs (measured after 5 minutes) at screening outside of the following ranges:
Cardiac/QT risk:
Participants will receive the standard 200 mg tafenoquine dose (200 mg daily for 3 days) followed by 200 mg weekly for two weeks to check for tolerability and adverse effects.
Drug: Tafenoquine prophylaxis
The same participants from Part 1 will be administered a monthly dose of tafenoquine (600 mg total, given as 300 mg split over 2 days) for two consecutive months. This monthly dose of 600 mg tafenoquine is designated the "low" monthly tafenoquine dose.
Drug: Tafenoquine prophylaxis
The same participants from Parts 1 and 2 will be administered a monthly dose of tafenoquine (800 mg total, given as 400 mg split over 2 days) for two consecutive months. This monthly dose of 800 mg tafenoquine is designated the high monthly tafenoquine dose
Drug: Tafenoquine prophylaxis
The study will be conducted in three parts with 200 participants invited to participate in the study. * Part 1 consist of 200 participants to be administered a loading dose of 600 mg tafenoquine (200 mg daily for 3 days) followed by 200 mg weekly for two weeks. * Part 2: The same participants from Part 1 will be administered a monthly dose of tafenoquine (600 mg total, given as 300 mg split over 2 days) for two consecutive months. This monthly dose of 600 mg tafenoquine is designated the "low" monthly tafenoquine dose. * Part 3: The same participants from Parts 1 and 2 will be administered a monthly dose of tafenoquine (800 mg total, given as 400 mg split over 2 days) for two consecutive months. This monthly dose of 800 mg tafenoquine is designated the high monthly tafenoquine dose.
Also known as: TQ
Tafenoquine dose escalating study to compare the frequency of treatment-related safety and adverse events and minimum inhibitory concentration of the medication after weekly 200 mg tafenoquine and two monthly (600 mg and 800 mg) tafenoquine regimens.
In a dose escalating study in the same healthy participants compare the frequency of treatment-related safety and adverse events (AEs) after weekly 200 mg tafenoquine and two monthly (600 mg and 800 mg) tafenoquine regimens and to determine whether the safety and tolerability profiles in healthy participants taking monthly doses of 600 mg or 800 mg tafenoquine are comparable in the same participants taking weekly 200 mg tafenoquine.
Time frame: six months
Characterize the PK profiles of tafenoquine
A drug-free venous blood sample will be obtained from each participant at D0. PK blood sampling will be done to cover the absorption phase (Cabs, 1 to 4 hours after dosing), maximum concentration (Cmax, 22 to 24 hours after dosing), mid weekly or monthly concentration (Cmid) after dosing and the minimum concentration (Cmin) before the next dose of tafenoquine. PK parameters for each tafenoquine regimen will be calculated using a nonlinear mixed-effects modeling approach. The population PK model will evaluate the impact of clinically appropriate covariates, such as body weight, BMI, age and dose. Median (95% CI) Cmax and Cmin values of tafenoquine will also be estimated for the participants for each tafenoquine regimen.
Time frame: six months
Characterize the pharmacokinetic/pharmacodynamic (PK/PD) relationship
All collected PK samples will be analyzed using nonlinear mixed-effects modelling to describe the concentration-time profile of tafenoquine, and the association between drug exposure and potential adverse reactions. Different absorption and disposition models will be assessed to develop the structural PK model. Clinical covariates will be evaluated with a traditional forward addition/backward elimination approach, with particular focus on the influence of dose, body weight, BMI, and age. The PK model will be summarized by population mean estimates for structural model parameters, as well as estimated precision and between-patient variability in the same parameters. Secondary PK parameters, such as maximum and minimum tafenoquine concentrations, will be derived for each dosing regimen in order to evaluate the prospect of reaching effective concentrations for participants within each of the three tafenoquine regimens.
Time frame: six months
Determine the association of tafenoquine and its metabolite 5,6, orthoquinone in red blood cells
Because of the limited data on the association of tafenoquine in blood cells, venous blood and plasma samples will be measured in this study. Blood and plasma concentrations of tafenoquine and its metabolite, 5,6-orthoquinone will be quantified by liquid chromatography mass spectrometry (LCMS) in the selected reaction monitoring mode using heated electrospray ionization in positive ion mode. Blood and plasma samples (50 μL) will be precipitated with 200 μL of acetonitrile containing the internal standard. After centrifugation at 20,817 x g for 5 minutes at 4°C, an aliquot (10 μL) of the supernatant will be injected onto the analytical column. orthoquinone in red blood cells, the site of action of the drug's blood schizontocidal activity.
Time frame: six months
Determine the ex vivo antimalarial activity of tafenoquine in participants' plasma samples
Thirty participants will be invited to provide four additional 8 ml blood samples for assessing the ex vivo antimalarial activity of tafenoquine (TQ) and its metabolites. A blood sample will be collected before the 1st TQ dose to determine if their plasma can support the in vitro growth of P. falciparum isolates. After the collection of the pre-dose TQ blood sample, Cohort A participants will then provide additional blood samples after the 1st weekly 200 mg TQ dose and 1st monthly (600 mg and 800 mg) TQ doses. For Cohort B participants they will provide additional blood samples after the 2nd weekly 200 mg TQ dose and 2nd monthly (600 mg and 800 mg) TQ doses. Comparison of the inhibitory dilution of plasma samples on weekly and monthly TQ administration will be made to see which results in a 50% inhibition of uptake of \[3H\]-hypoxanthine (surrogate for parasite growth) compared to drugfree plasma samples (controls) against P. falciparum strains with different levels of drug.
Time frame: six months
Plan to share: No — All participants at the screening visit who fulfill the selection criteria and sign the ICF will be allocated a unique sequential screening study ID number by the clinical trial site. This will be a 3-digit number (starting at 001) prefixed by the letter "STQ" (i.e. STQ001, STQ002, etc. in ascending order). The letters "S" stands for screening and "TQ" for tafenoquine. A log of the screening ID numbers will be recorded in the register of data (RoD).
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