This is a Clinical Study to Assess Whether the Combination of SJ733 and Tafenoquine Will be a Safe and Rapidly Acting Anti-malarial for the Radical Cure of P. Vivax Malaria (SJ733-2002)

A Phase 2B Trial of the Combination of SJ733 and Tafenoquine for Radical Cure of P. Vivax Malaria in Comparison to Chloroquine-Tafenoquine

The goal of this Phase 2b study is to examine the safety and efficacy of the combination of SJ733, an investigational agent, and tafenoquine for the radical cure of uncomplicated P. vivax malaria monoinfection in adult participants and determine the contributions of SJ733 to the effect. SJ733 will be administered in a 1-, 2-, or 3-day treatment schedule in combination with a single dose of tafenoquine.

Study Overview

• Status: Not yet recruiting
• Conditions: Malaria; Malaria Vivax; Radical Cure
• Intervention / Treatment: Drug: SJ733/TQ placebo; Drug: CQ/TQ Placebo; Drug: CQ/TQ; Drug: SJ733 (3-day)/TQ; Drug: SJ733 (2-day ) /TQ; Drug: SJ733(1-day)/TQ

Detailed Description

SJ733-2002 study is a blinded, randomized, placebo- and active comparator-controlled study to examine the safety and efficacy of combining 1, 2, or 3 sequential daily doses of SJ733 with a single dose of TQ given on Day 1 for the radical cure of uncomplicated P. vivax malaria. This study will also establish the role of SJ733 in driving blood stage and liver stage parasite killing and any pharmacological interactions with Tafenoquine (TQ). Hence, this study includes placebo controlled SJ733 and Chloroquine (CQ) monotherapy arms. The six arms in this study will be run simultaneously and participants randomized with a 1:1:1:1:1:1 ratio until all arms are filled. All participants will be monitored for 180 days, with parasitemia endpoints measured on Days 7, 14, 21, 28, 35, 42, 60, 120, and 180 to provide maximum comparability to historical studies. At all times during these studies any participants that develop symptomatic disease or detectable parasitemia will be rescued with local standard-of-care (according to national guidelines). Any participant who does not relapse during the study will be treated following the last day of the study with the same rescue therapy.

• Study Type: Interventional
• Enrollment (Estimated): 104
• Phase: Phase 2

Contacts and Locations

• Study Contact: Name: Rodney K Guy, PhD; Phone Number: 901- 481-7251; Email: rguy@umn.edu
• Study Contact Backup: Name: Gaurav Shoeran, PhD; Email: gshoeran@umn.edu

Study Locations

• Peru
  • Loreto
    • Iquitos, Loreto, Peru
      • Asociación Civil Selva Amazónica (ACSA)
      • Contact: Ana Rimachi; Phone Number: +51 65 236277; Email: arimachi@acsaperu.org

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Body weight between 45 kg and 90 kg inclusive.
• Presence of mono-infection of P. vivax confirmed by: Fever, as defined by axillary temperature ≥ 37.5°C or oral/rectal/tympanic temperature ≥ 38°C, or history of fever in the previous 24 hours (history of fever must be documented) and, Microscopically confirmed parasite infection: 1,000 to 40,000 asexual parasite count/µL blood
• Written informed consent provided by participant, in accordance with local practice. If the participant is unable to write, witnessed consent is permitted according to local ethical considerations.
• Ability to swallow oral medication.
• Ability and willingness to participate and to comply with the study requirements.
• Agreement to hospitalization for at least 72 hours and/or until malarial parasites are not detected by microscopy on 2 consecutive occasions.
• Agreement to come back to the hospital on Days 4, 7, 14, 21, 28, 35, 42, 60, 120, and 180.

• A female participant meets eligibility in this study if she is non-pregnant, non-lactating and if she is of: non-childbearing potential defined as: post-menopausal (12 months of spontaneous amenorrhea or <6 months of spontaneous amenorrhea with serum FSH >40 mIU/mL), pre-menopausal and has had a hysterectomy, a bilateral oophorectomy (removal of the ovaries), or a bilateral tubal ligation with medical report verification, negative pregnancy test or, child-bearing potential, with a negative pregnancy test at screening, and agrees to comply with one of the following during the treatment stage of the study and for a period of 75 days after stopping study treatment:

  i. Use of oral, implantable, or injectable hormonal contraceptive, either combined or progestogen alone, used in conjunction with barrier method (condom or diaphragm).

ii. Use of an intrauterine device with a documented failure rate of <1% per year.

iii. Double barrier method consisting of condom and diaphragm. iv. Male partner who is sterile prior to the female participant's entry into the study and is the sole sexual partner for that female.

v. Complete abstinence from intercourse throughout the study and for a period of 75 days after stopping study treatment.

• A male participant meets eligibility in this study if he meets one of the following conditions:

  1. is sterile prior to participating in the study.
  2. agrees to the use of a contraceptive method (such as a condom) through the administration of study treatment and for a period of 75 days after stopping study treatment.
  3. agrees to complete abstinence from intercourse throughout the study and for a period of 75 days after stopping study treatment.

Exclusion Criteria:

• Signs and symptoms of severe/complicated malaria according to the World Health Organization Criteria 2010.
• Mixed Plasmodium infection or Plasmodium mono-infection with any Plasmodium species other than P. vivax.
• Severe vomiting, defined as more than three times in the 24 hours prior to the planned first dose of drug, or severe diarrhea defined as 3 or more watery stools per day.
• Severe malnutrition (defined as the weight-for-height being below -3 standard deviation or less than 70% of median of the NCHS/WHO normalized reference values).
• The presence of a significant medical or psychiatric condition, or any other serious or chronic clinical condition requiring hospitalization, or any other condition that in the opinion of the investigator precludes participation in the study.
• Female participants must not be lactating or pregnant as demonstrated by a negative serum point-of-care pregnancy test pre-dose (the result of the pre-dose assessment must be confirmed negative prior to dosing).
• Employment under the direct supervision of the investigators or study staff.

• Clinically significant alterations to hematologic or clinical chemistry parameters that in the opinion of the investigator precludes participation in the study, including:

  1. AST/ALT > 3 x upper limit of normal range (ULN) and total bilirubin is normal.
  2. AST/ALT > 2 x ULN and total bilirubin is >1 and <2 x ULN and conjugated bilirubin is > 2x ULN.
  3. Serum creatinine levels > 2 x ULN
  4. Uncorrected electrolyte abnormalities [> 3x ULN or LLN]

  i. Potassium[hypokalemia] ii. Magnesium [hypomagnesemia] e. Hb level < 9 g/dL f. Platelet level < 50,000/mm3

• Clinically significant alterations to cardiac function

  1. Unstable angina with elevated serum cardiac biomarkers, ECG changes, etc.; those with NSTE-ACS, NSTEMI, STEMI, or definite acute coronary syndrome.
  2. Congestive heart failure
  3. Recent history of Myocardial Infarction
  4. QT prolongation (>450 milliseconds (ms) in men and 460 ms in women)
• Participation in a clinical study of another small investigational molecule within 30 days or investigational biologic within 90 days prior to study enrollment or planning to begin such participation during the study.

• Received any antimalarial treatment (alone or in combination) in the past containing:

  1. Tafenoquine within the previous 4 months
  2. Piperaquine, mefloquine, naphthoquine or sulphadoxine / pyrimethamine within the previous 5 months
  3. Amodiaquine or chloroquine within the previous 5 months
  4. Any artemisinin (artesunate, artemether, arteether or dihydroartemisinin), quinine, halofantrine, lumefantrine and any other anti-malarial treatment or antibiotics with antimalarial activity (including cotrimoxazole, tetracyclines, quinolones and fluoroquinolones, and azithromycin) within the past 3 months.
• Known history of hypersensitivity, allergic, or adverse reactions to SJ733, tafenoquine or other 8-aminoquinolines, or chloroquine or other 4-aminoquinolines.
• Current use of prohibited concomitant medications (Appendix III)
• Known neuropsychiatric disorders.
• G6PD deficiency <70% normal enzyme activity.
• Prohibited use of metoclopramide, antibiotics including fluoroquinolones
• Positive HIV and/or Hepatitis B, C test results

Study Plan

How is the study designed?

Design Details

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

Number of Arms

6

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Arm1 - SJ733 600 mg for 3 days and Tafenoquine Placebo; SJ733 (600 mg) once a day for 3 consecutive days combined with tafenoquine placebo on the first day	Drug: SJ733/TQ placebo; SJ733 combined with Tafenoquine Placebo; Other Names: SJ733; Tafenoquine Placebo
Experimental: Arm 2- Chloroquine and Tafenoquine Placebo; Chloroquine (600 mg) for 2 consecutive days then Chloroquine (300 mg) for 1 day, combined with tafenoquine placebo on the first day	Drug: CQ/TQ Placebo; Chloroquine combined with Tafenoquine Placebo; Other Names: Chloroquine; Tafenoquine Placebo
Active Comparator: Arm 3 - Chloroquine and Tafenoquine; Chloroquine (600 mg) for 2 consecutive days then Chloroquine (300 mg) for 1 day, combined with tafenoquine (300 mg) once on the first day	Drug: CQ/TQ; Chloroquine combined with Tafenoquine; Other Names: Chloroquine; Tafenoquine
Experimental: Arm 4a -SJ733 for three days and Tafenoquine; SJ733 (600 mg) once a day for 3 consecutive days combined with tafenoquine (300 mg) once on the first day	Drug: SJ733 (3-day)/TQ; SJ733 (3-day schedule) combined with Tafenoquine; Other Names: SJ733; Tafenoquine
Experimental: Arm 4b - SJ733 for 2 days and Tafenoquine; SJ733 (600 mg) once a day for 2 consecutive days, followed by SJ733 placebo for 1 day, combined with tafenoquine (300 mg) once on the first day	Drug: SJ733 (2-day ) /TQ; SJ733 (2-day schedule) combined with Tafenoquine; Other Names: SJ733; Tafenoquine
Experimental: Arm 4c - SJ733 for one day and Tafenoquine; SJ733 (600 mg) once, followed by SJ733 placebo for 2 days, combined with tafenoquine (300 mg) once on the first day	Drug: SJ733(1-day)/TQ; SJ733 (1 day schedule) combined with Tafenoquine; Other Names: SJ733; Tafenoquine

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Parasitological Recurrence Free survival (RFS)	Recurrence free survival (RFS), defined as non-relapses of P. vivax at 180 days given parasitemia clearance at 14 days.	14 - 180 days for each arm
Clinical Recurrence Free Survival	Absence of malaria-related clinical signs or symptoms over 180 days following confirmed parasitemia clearance at Day 14.	14 to 180 days for each arm
Percentage of patients with treatment related adverse events	Incidence, severity, drug-relatedness, and seriousness of adverse events	1 to 180 days for each arm
Percent of patients with clinically significant abnormal vital signs	Number of and seriousness of with clinically significant abnormal vital signs including changes from baseline	1 to 180 days for each arm
Percent of patients with a decrease in hemoglobin (HB) > 2 g/dL from baseline to an absolute value of <7 g/dL	Proportion of participants with a decrease in hemoglobin (Hb): > 2 g/dL from baseline to an absolute value of < 7 g/dL	1 to 180 days for each arm
Percent of patients with an Absolute Neutrophil Count < 1000/μL after baseline	Proportion of participants with an absolute neutrophil count < 1,000/μL after baseline	1 to 180 days for each arm
Percent of patients with significant changes in ECG findings	Proportion of participants with significant changes in ECG findings, including heart rate, ECG intervals (PR, QTcB, QTcF), conduction changes or abnormalities	1 to 180 days for each arm
Percent of patients with clinically significant increases in venous methemoglobin levels	Proportion of participants with clinically significant increases in venous methemoglobin levels	1 to 180 days for each arm

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Area Under the Plasma Concentration Time Curve (AUC)	AUC of SJ733, its primary metabolite, SJ506, and tafenoquine	180 days
Maximum Plasma Concentration (Cmax)	Cmax of SJ733, its primary metabolite, SJ506, and tafenoquine	180 days
Number of participants with signs and symptoms of uncomplicated P. vivax malaria infection	Proportion of participants with symptoms or physical examination signs related to uncomplicated P. vivax malaria (e.g., headache, nausea, fatigue, fever auxiliary temperature, >/= 37.5 C, chills/shivering/rigors, prostration, conjunctival jaundice, and respiratory distress)	180 days for each arm
Parasite clearance Time	Parasite Clearance Kinetics in participants with P. vivax malaria infection as measured by Microscopy	72 hours for each arm

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Correlation between microscopy and PCR measures of parasite clearance kinetics / efficacy	Effect of the proposed three-day therapy on PCR adjusted parasitological outcomes, complementing microscopy-based assessments, in participants with P. vivax malaria	180 days for each arm

Collaborators and Investigators

• Sponsor: R. Kiplin Guy
• Collaborators: University of Minnesota; Congressionally Directed Medical Research Programs; Global Health Innovative Technology Fund
• Investigators: Principal Investigator: Alejandro L Cuentas,, MD, PhD, Asociación Civil Selva Amazónica (ACSA), Iquitos, Loreto - Perú; Study Director: Rodney K Guy, PhD, University of Minnesota

Publications and helpful links

General Publications

• Gaur AH, McCarthy JS, Panetta JC, Dallas RH, Woodford J, Tang L, Smith AM, Stewart TB, Branum KC, Freeman BB 3rd, Patel ND, John E, Chalon S, Ost S, Heine RN, Richardson JL, Christensen R, Flynn PM, Van Gessel Y, Mitasev B, Mohrle JJ, Gusovsky F, Bebrevska L, Guy RK. Safety, tolerability, pharmacokinetics, and antimalarial efficacy of a novel Plasmodium falciparum ATP4 inhibitor SJ733: a first-in-human and induced blood-stage malaria phase 1a/b trial. Lancet Infect Dis. 2020 Aug;20(8):964-975. doi: 10.1016/S1473-3099(19)30611-5. Epub 2020 Apr 8.
• uy, R. K. 2023. "NCT04709692: Efficacy of SJ733 in Adults With Uncomplicated Plasmodium Falciparum or Vivax Malaria." In. https://clinicaltrials.gov/ct2/show/NCT04709692?term=SJ733&draw=2&rank=2.
• Gaur AH, Panetta JC, Smith AM, Dallas RH, Freeman BB 3rd, Stewart TB, Tang L, John E, Branum KC, Patel ND, Ost S, Heine RN, Richardson JL, Hammill JT, Bebrevska L, Gusovsky F, Maki N, Yanagi T, Flynn PM, McCarthy JS, Chalon S, Guy RK. Combining SJ733, an oral ATP4 inhibitor of Plasmodium falciparum, with the pharmacokinetic enhancer cobicistat: An innovative approach in antimalarial drug development. EBioMedicine. 2022 Jun;80:104065. doi: 10.1016/j.ebiom.2022.104065. Epub 2022 May 19.

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): November 20, 2028
• Study Completion (Estimated): November 20, 2028

Study Registration Dates

• First Submitted: February 18, 2026
• First Submitted That Met QC Criteria: February 18, 2026
• First Posted (Actual): February 24, 2026

Study Record Updates

• Last Update Posted (Actual): May 28, 2026
• Last Update Submitted That Met QC Criteria: May 22, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: SJ733; SJ733 with Tafenoquine
• Additional Relevant MeSH Terms: Vector Borne Diseases; Mosquito-Borne Diseases; Infections; Protozoan Infections; Parasitic Diseases; Malaria; Malaria, Vivax; Heterocyclic Compounds; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Quinolines; Aminoquinolines; Chloroquine; tafenoquine; SJ733
• Other Study ID Numbers: 108683; PR241297 (Other Grant/Funding Number: Department of Defense); G2022-218 (Other Grant/Funding Number: Global Health Innovation Technology Fund)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No