The Assessing Radical Cure Treatment In routine Care Study (ARCTIC)


ARCTIC (Assessing Radical Cure Treatment In routine Care) was an operational feasibility study looking at the real-world use of point-of-care, Glucose-6-Phosphate Dehydrogenase (G6PD) testing and appropriate radical cure treatment with tafenoquine (TQ) or primaquine (PQ) within the public health system in Thailand. It was the first feasibility study using single-dose TQ in routine care in the Asia-Pacific region, and was conducted in the Mae Hong Son and Yala provinces of Thailand, which have high rates of P. vivax malaria. 

The study was completed in two phases. The first phase was conducted in 5 hospitals from September to December 2022. An Independent Study Oversight Committee then reviewed interim results and recommended that the study continue to phase 2, which then ran between January and August 2023. Phase 2 continued in the original 5 hospitals and expanded to include 4 malaria clinics as well. 

The study was sponsored by the Division of Vector-Borne Diseases (DVBD) within the Thai Ministry of Public Health (MoPH). Medicines for Malaria Venture provided technical support and funding.    

Why study tafenoquine use in routine settings?

As a single-dose relapse prevention treatment, tafenoquine is able to overcome compliance challenges associated with 14-day primaquine - the current standard of care. This represents a significant advance for elimination efforts, as more people may be able to be effectively treated. 

Like primaquine, tafenoquine can cause haemolysis in individuals who are G6PD deficient, so testing individuals to ascertain their G6PD status prior to treatment is important for patient safety. Ahead of introducing the new treatment, the DVBD wanted to be confident that healthworkers would be able to accurately perform the test and provide the appropriate treatment with either PQ or TQ based on G6PD enzymatic activity. G6PD testing was carried out for all patients, and treatment was determined based on the patients G6PD activity.  


Expedited Policy Adoption

In May 2023, based on a review of the data from the first 120 patients enrolled in the ARCTIC study, the National Communicable Diseases Committee under the Communicable Disease Act & National Malaria Treatment Drug Committee approved the use of TQ for radical cure of P. vivax patients from 16 years of age.  

The Committee also passed a resolution to begin rolling out TQ in hospitals in 6 high-burden provinces on the Myanmar-Thai border to control an ongoing P. vivax outbreak. This includes Mae Hong Son, Tak, Kanchanaburi, Ratchaburi, Petchaburi, and Prachuap Khiri Khan provinces. Thailand’s efforts to implement G6PD testing and TQ for routine care for P. vivax are paving the way for other countries to follow suit.

The ARCTIC study: optimizing P. vivax radical cure in Thailand

Key Findings and Conclusions

Key Findings: 

  • No cases of acute hemolytic anemia were recorded among study participants. 
  • High follow-up rates for TQ: 100% at Day 5 and 92% at Day 14. 
  • All patients were treated with appropriate P. vivax radical cure (TQ / PQ) in line with G6PD activity. 
  • TQ (and PQ) were correctly used in 100% of cases based on G6PD activity. 

Study Experience: 

  • Initial concerns about implementing G6PD testing and TQ were alleviated after experience in the field. 
  • Health workers expressed increased confidence and competency with the tools after learning by doing.  
  • It is critical to ensure health worker competency and to ensure training for new staff is conducted.  
  • Good communication is important to ensure staff feel comfortable with the new tools. Informal chats on ‘Line app’, real-time support and guidance from experienced staff were important enablers. 
  • Patient awareness about the need for G6PD testing and signs/symptoms of P. vivax malaria and hemolysis increased throughout the study. 
  • Implementation in malaria clinics is less complicated than in hospitals because of fewer staff and simpler systems, but there is still a need to ensure competency for quality control of G6PD testing.