Phase 2
N=600
Long-Term Safety Study of Tafenoquine
Healthy Volunteers
Bottom Line
View on ClinicalTrials.gov: NCT03320174 ↗Enrolled (actual)
600
Serious AEs
6.7%
Results posted
Apr 2026
Primary outcome: Primary: Serious Ophthalmic Safety Event — 45; 48 Participants
Study Design & Population
- Study type
- Interventional
- Phase
- Phase 2
- Interventions
- Tafenoquine (Drug); Placebo (Other)
- Age
- Adult · 18+ yrs
- Sex
- All
- Sponsor
- 60 Degrees Pharmaceuticals LLC
- Primary completion
- Jul 2021
Outcome Measures
| Outcome | Result | p-value |
|---|---|---|
| PRIMARY Serious Ophthalmic Safety Event |
45; 48 | — |
| SECONDARY Number of Participants With Mean Change From Baseline in Key SD OCT Parameters |
1; 0; 3; 0; 12; 14 | 0.49 |
| SECONDARY Number of Participants With Ellipsoid or Interdigitating Zone Disruption |
11; 13; 15; 19 | 0.84 |
| SECONDARY Number of Participants With Mean Change From Baseline in Best Corrected Visual Acuity |
0; 2 | — |
| SECONDARY Number of Participants With Corneal Deposits From Slit Lamp Examination of the Corneal Epithelium |
176; 47 | — |
| SECONDARY Number of Participants With New Abnormalities Compared With Baseline Observed With Color Retinal Digital Photography |
114; 16 | — |
| SECONDARY Number of Participants With New Abnormalities Compared With Baseline Observed With Microperimetry |
15; 14 | 0.85 |
| SECONDARY 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) |
2; 0 | — |
| SECONDARY Proportion of Participants Who Develop a Color Deficiency Using the Farnsworth-Munsell 100 (FM-100) Hue Test |
2; 3 | — |
| SECONDARY Number of Participants Who Develop a Loss of 0.12 or Greater Logarithm of Contrast Sensitivity (logCS) on the Mars Letter Contrast Sensitivity Test |
32; 40 | 0.38 |
| SECONDARY 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 |
61; 64 | 0.76 |
| SECONDARY Number of Participants With an AE of Dizziness or Vertigo and Severity as Assessed by the Dizziness Handicap Inventory |
20; 32 | 0.083 |
Summary
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.
Eligibility Criteria
Main Inclusion Criteria:
- Completion of the written informed consent process (signed).
- Male or female age 18 to 55 years inclusive, in good health as assessed by the Investigator.
- Normal G6PD enzyme activity levels as defined by the parameters of the specific G6PD test employed at the local laboratory.
- Negative HBsAg and HCV, HIV-1, HIV-2 antibody screen at the screening visit.
- Negative serum pregnancy test.
- Use acceptable method of birth control.
- 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.
- Willing and able to comply with all scheduled visits, treatment plan, laboratory tests, and other study procedures.
Main Exclusion Criteria:
- History of allergy or intolerance to tafenoquine, primaquine or any excipients.
- History of thalassemia or current or past history of methemoglobinemia or methemoglobin >2% at screening.
- History of eye disease or surgery
- 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.
- Any current diagnosis of Axis I psychiatric disorders
Data sourced from ClinicalTrials.gov (NCT03320174). Outcome figures and adverse-event rates are extracted automatically from the registry's posted results and are provided for clinician reference, not as a substitute for the primary publication.