Developing a single-exposure cure to stop the relapse
Tafenoquine is in phase III development with GSK. The aim is to investigate its potential as a single-exposure medicine to prevent the relapse of P. vivax malaria, with the current intention of submitting a new drug application to the US FDA1 in 2017. If successful, it would be the first new medicine for relapsing malaria to progress to regulatory approval in over 60 years. Tafenoquine would be used alongside a blood-stage medicine, which together would cure the current malaria infection and prevent a future relapse.
Tafenoquine is an 8-aminoquinoline from the same chemical family as the current standard of care, primaquine. This class of drugs is associated with haemolytic side-effects in patients deficient in the enzyme glucose-6-phosphate dehydrogenase (G6PD). To ensure tafenoquine is well tolerated by patients, they will need to be tested for G6PD deficiency before treatment – as they should be today before taking primaquine.
GSK is working with PATH to accelerate the development of a G6PD point-of-care test.
Penny Grewal Daumerie, MMV’s Director, Access and Delivery, and MMV access lead for tafenoquine, explains the excitement around the potential new medicine and the plan to ensure patient access if approved.
1. What is exciting about tafenoquine, for you and the malaria community?
As a single-exposure cure, tafenoquine could potentially overcome the compliance issue of a 7- or 14-day course and revolutionize the treatment landscape for relapsing malaria. It would provide countries with an effective tool to tackle the P. vivax hypnozoite reservoir, thereby reducing transmission and the overall disease burden. This would pave the way for elimination. As patients will be screened for G6PD deficiency before receiving tafenoquine, health-care providers will have greater confidence in treating their patients.
It is a privilege to work with GSK on an access strategy for a medicine that we hope will meet a real unmet need.
2. What’s involved in the process of ensuring patient access to tafenoquine?
Tafenoquine is a fairly complex proposition as it entails the adoption and roll-out of two products – a G6PD test and the medicine itself. That makes access planning all the more challenging!
Before we could develop an access strategy for tafenoquine we needed a whole range of information including P. vivax epidemiology, how the disease is managed, why countries do or do not implement a radical cure, G6PD prevalence, views on testing, supply chain issues etc. To get this information, we conducted market and desk research, and held consultative meetings with experts, policy-makers, malaria control programme managers and other stakeholders. This provides the basis for the joint access and delivery strategy being developed by MMV, GSK, PATH and the Bill & Melinda Gates Foundation to help ensure timely access to a safe and effective radical cure.
Richard Rankin, Global Marketing Director, Infectious Diseases, GSK, explains the key challenges that must be overcome to support optimal use of tafenoquine in malaria-endemic countries, if approved.
1. What are the specific challenges involved in ensuring patient access for tafenoquine?
One of the biggest challenges is managing the possibility of haemolysis in patients that are G6PD deficient. Before tafenoquine administration, patients will need their G6PD levels tested to ensure tafenoquine is used safely and effectively. Right now no suitable quantitative G6PD tests are available for reliable use in the field. GSK is collaborating with PATH and diagnostic developers and a prototype device is already being tested in the laboratory. One of the biggest challenges in terms of implementation will be to ensure the medicines and tests are available together.
2. How is the team working to overcome these challenges?
By working in partnership. We are collaborating with MMV, PATH and the Gates Foundation to co-create a patient access plan. This includes thinking through how tafenoquine and a G6PD-deficiency test could be introduced in close consultation with malaria-control programme managers, experts and WHO.
I think one of the biggest achievements in terms of access planning for tafenoquine has been obtaining the input of several partners at an early stage to develop a comprehensive plan. We believe this plan will support the success of the programme.
3. What are the next steps to ensure patient access should tafenoquine receive stringent approval?
Once tafenoquine and a point-of-care test have been approved for use, we will continue to work in partnership and solicit greater involvement from the malaria community. GSK and MMV are developing this medicine to meet the needs of populations afflicted by P. vivax malaria. Our objective is to have tafenoquine widely available and affordable in malaria-endemic countries. That’s what is driving us. GSK intends to provide the medicine at an affordable price to enable wide patient access in these countries.
It’s absolutely critical that once we have filed an application for tafenoquine for regulatory approval, we work more closely with affected countries to see how we can support their implementation efforts. For this to succeed, it needs to be driven by the national malaria-control programme managers. 4. What has it been like to work with MMV on access planning for tafenoquine? We really value the contribution that MMV makes in terms of partnership and contacts with policy-makers at both the global and regional level. The knowledge, expertise and links MMV has with the wider malaria community are unique.
1. United States Food and Drug Administration
Penny Grewal Daumerie, MMV’s Director, Access and Delivery & Richard Rankin, Global Marketing Director, Infectious Diseases, GSK