Long-Term Safety Study of Tafenoquine

March 30, 2026 updated by: 60 Degrees Pharmaceuticals LLC

Single Site, Randomized, Double Blind, Placebo-Controlled Study to Assess the Long-Term Safety of Tafenoquine

This randomized, double-blind, placebo controlled study will involve 600 healthy (Glucose-6-Phosphate Dehydrogenase [G6PD] normal) volunteers. Participants who meet the eligibility criteria will be randomized (ratio 1:1) to receive a loading dose of either tafenoquine 200 mg (2 x 100 mg tablets) or placebo daily for three consecutive days, followed by study treatment (tafenoquine 200 mg or placebo) once per week for 51 weeks, with safety follow-up visits at Weeks 4, 12, 24, and 52. All participants will return to the clinic at Week 64 for an end of study visit. If the participant has an ongoing AE at the Week 64 visit will continue to be assessed for up to 3 more times at approximately 12-week intervals or until resolution or stabilization of the AE whichever is earlier.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
600

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Australia
    • Western Australia
      • Nedlands, Western Australia, Australia, 6009
        • Linear Clinical Research
  • United States
    • Colorado
      • Colorado Springs, Colorado, United States, 80909
        • Retina Consultants of Southern Colorado
    • Texas
      • McAllen, Texas, United States, 78503
        • Valley Retina Institute

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years to 55 years (Adult)

Accepts Healthy Volunteers

Yes

Description

Main Inclusion Criteria:

  1. Completion of the written informed consent process (signed).
  2. Male or female age 18 to 55 years inclusive, in good health as assessed by the Investigator.
  3. Normal G6PD enzyme activity levels as defined by the parameters of the specific G6PD test employed at the local laboratory.
  4. Negative HBsAg and HCV, HIV-1, HIV-2 antibody screen at the screening visit.
  5. Negative serum pregnancy test.
  6. Use acceptable method of birth control.
  7. Hematology, biochemistry and urinalysis results at screening that are within the local laboratory reference range or, if outside the range, not clinically significant as judged by the Investigator in accordance with approved clinically acceptable laboratory ranges, documented prior to study start.
  8. Willing and able to comply with all scheduled visits, treatment plan, laboratory tests, and other study procedures.

Main Exclusion Criteria:

  1. History of allergy or intolerance to tafenoquine, primaquine or any excipients.
  2. History of thalassemia or current or past history of methemoglobinemia or methemoglobin >2% at screening.
  3. History of eye disease or surgery
  4. Having previously received hydroxychloroquine for skin conditions or rheumatological diseases, chloroquine for malaria, tamoxifen, amiodarone or other drugs that may affect the optic nerve/retina/cornea within 30 days or 5 half-lives (whichever is longer) of study start. There are no travel restrictions, but the choice of concurrent anti-malarial must be atovaquone-proguanil if the participant chooses to take a registered antimalarial drug while travelling.
  5. Any current diagnosis of Axis I psychiatric disorders

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Active Comparator: Tafenoquine 200 mg (2 x 100 mg tablets)
Tafenoquine 200 mg (2 x 100 mg tablets) daily for three consecutive days, followed by study treatment (tafenoquine 200 mg or placebo) once per week for 51 weeks
Drug: Tafenoquine
Tafenoquine 200mg
Placebo Comparator: Placebo
Placebo daily for three consecutive days, followed by study treatment (tafenoquine 200 mg or placebo) once per week for 51 weeks
Other: Placebo
Placebo

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Serious Ophthalmic Safety Event
Time Frame: After 12 months of exposure to study drug
Number of Participants with One or More protocol-defined serious ophthalmic safety event (SOSE) assessed by retinal changes from baseline using SD-OCT and qFAF. SOSE is assessed by significant retinal changes from baseline using SD-OCT and qFAF.
After 12 months of exposure to study drug

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Number of Participants With Mean Change From Baseline in Key SD OCT Parameters
Time Frame: After 12 months of exposure to study drug

Mean change from baseline in key SD OCT parameters including central subfield thickness, total macular volume, and parafoveal (inner ring of Early Treatment Diabetic Retinopathy Study, and retinal thickness.

Clinically significant change from baseline for central subfield thickness [change from baseline of at least 40 µm (15% change)].

Clinically significant change from baseline for total macular volume [change of > 10% (0.86 mm3) from baseline].

Clinically significant change from baseline for parafoveal (inner ring) retinal thickness [change from baseline of at least 10 µm].

Clinically significant change from baseline for qFAF (change in mid-ring qFAF unit from baseline of at least 12% in both eyes at the same visit).
After 12 months of exposure to study drug
Number of Participants With Ellipsoid or Interdigitating Zone Disruption
Time Frame: After 12 months of exposure to study drug
Any ellipsoid or interdigitating zone disruption within the ETDRS grid
After 12 months of exposure to study drug
Number of Participants With Mean Change From Baseline in Best Corrected Visual Acuity
Time Frame: After 12 months of exposure to study drug
Mean change from baseline in BCVA score, the number of participants that have any clinically significant change in ETDRS BCVA (defined as ≥15 letter change [≥ 3 lines] of change in ETDRS BCVA at 4 meters).
After 12 months of exposure to study drug
Number of Participants With Corneal Deposits From Slit Lamp Examination of the Corneal Epithelium
Time Frame: After 12 months of exposure to study drug
Slit lamp examination was use to detect and grade corneal deposits (also known as vortex keratopathy or cornea verticillata) and retinal abnormalities arising from drug-induced phospholipidosis.
After 12 months of exposure to study drug
Number of Participants With New Abnormalities Compared With Baseline Observed With Color Retinal Digital Photography
Time Frame: After 12 months of exposure to study drug
Corneal deposits as determined by digital corneal photographs that are indicative of cornea verticillata also known as vortex keratopathy
After 12 months of exposure to study drug
Number of Participants With New Abnormalities Compared With Baseline Observed With Microperimetry
Time Frame: After 12 months of exposure to study drug
Microperimetry can be a useful tool for objective evaluation of macular function and progression of disease. Macular disease causes impairment of central vision, metamorphopsia, macropsia, micropsia and color vision defect. Microperimetry measures fixation stability which is associated with visual acuity.
After 12 months of exposure to study drug
Number of Participants With Any Clinically Significant Change in ETDRS BCVA (Defined as >15 Letter Change [≥ 3 Lines] of Change in ETDRS BCVA at 4 Meters)
Time Frame: After 12 months of exposure to study drug
Visual acuity was measured in a consistent way in order to detect any changes in vision as described in the Ophthalmic Reference Manual using a set of Early Treatment Diabetic Retinopathy Study (ETDRS) charts and a retro-illuminated box providing standardized illumination. Subjects are seated 4 meters from the letter chart and asked to read the letters. Letters read correctly count towards the total score. In addition, there are 5 letters in each of the 14 lines. The lines are of equal difficulty and follow a logarithmic progression of diminishing letter size related to the minimum angle of resolution. The endpoints include mean change from baseline in BCVA score, the proportion of participants that have any clinically significant change in ETDRS BCVA (defined as ≥15 letter change [≥ 3 lines] of change in ETDRS BCVA at 4 meters).
After 12 months of exposure to study drug
Proportion of Participants Who Develop a Color Deficiency Using the Farnsworth-Munsell 100 (FM-100) Hue Test
Time Frame: After 12 months of exposure to study drug
Color deficiency was assessed using the Farnsworth-Munsell 100 (FM-100) hue test
After 12 months of exposure to study drug
Number of Participants Who Develop a Loss of 0.12 or Greater Logarithm of Contrast Sensitivity (logCS) on the Mars Letter Contrast Sensitivity Test
Time Frame: After 12 months of exposure to study drug
The Mars letter contrast sensitivity test is a set of charts for testing peak visual contrast sensitivity. Subjects are asked to read to letters from left to right across the chart. The logarithm of contrast sensitivity (logCS) score is given by the log contrast sensitivity value at the lowest contrast letter just prior to two incorrectly identified letters, minus a scoring correction.
After 12 months of exposure to study drug
Number of Participants Who Develop a Psychiatric Disorder in Accordance With DSM-5 as Assessed With the Mini International Neuropsychiatric Interview (M.I.N.I.) 7.0.2 Assessment Questionnaire
Time Frame: After 12 months of exposure to study drug
Psychiatric disorders were reported as adverse events
After 12 months of exposure to study drug
Number of Participants With an AE of Dizziness or Vertigo and Severity as Assessed by the Dizziness Handicap Inventory
Time Frame: After 12 months of exposure to study drug
The period of observation for collection of AEs extended from the time of dosing (Day 1, Week 1 [Visit 2]) through the Week 64 follow-up visit. Proportion of participants with an AE of dizziness or vertigo are reported here.
After 12 months of exposure to study drug

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
60 Degrees Pharmaceuticals LLC

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
October 5, 2017

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
July 13, 2021

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
July 13, 2021

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
October 18, 2017

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 24, 2017

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
October 25, 2017

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 17, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 30, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
September 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 60PH04

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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Conditions

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