Human trials speed up delivery of malaria vaccines

Imagine volunteering to be infected with a disease that kills nearly 600,000 people a year. That is what Celeste Farmer, a psychology student at the University of Queensland in Australia, agreed to do in order to help researchers develop drugs to treat malaria.

"I'm healthy, but there are plenty of people out there who are not," she says. "It is important for people to donate their bodies like this to help others."

Ms Farmer is one of 230 volunteers who have taken part in trials using the "challenge model", in which healthy human subjects are infected with low doses of malaria to test the efficacy of new drug treatments.

Advocates say the trials, undertaken by the QIMR Berghofer Medical Research Institute and other global institutes, are speeding up the delivery of new anti-malaria drugs, saving pharmaceutical companies millions of dollars in R&D costs and providing hope for the development of more effective vaccines.

"While many new drugs and vaccines are being developed, it is difficult to determine which are the best to take to areas where malaria is a life-threatening disease," says James McCarthy, a professor at QIMR. "Malaria is becoming more resistant to existing treatments, which makes the speedy development of new drugs vital. These trials are helping to achieve this," he says.

The World Health Organisation reports that there were about 198m cases in 2013, mostly in Africa, Asia and South America which led to an estimated 584,000 deaths.

Under QIMR's challenge model, participants in the trials are injected with a sample of malaria that is much less than the amount that reaches the blood when a human catches the disease from a mosquito bite.

Volunteers are closely monitored using tests that measure the DNA of malaria parasites in the blood. This enables researchers to treat the volunteers before they become ill. They can administer trial drugs to monitor their effectiveness at tackling the disease and capture valuable information that can help develop treatments.

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"This method reduces costs, increases the speed of drug testing and provides a valid path to develop new malaria drugs," says Prof McCarthy. "By using this method, we have [ruled out] three trial drugs at an earlier stage than would normally be possible. The data we collect also enable us to guide the dosage applied in larger field studies."

None of the participants in the trials, which have continued for several years, have become ill, say the researchers - a positive outcome which they attribute to intensive monitoring and the timely deployment of proven drugs to kill the malaria parasites in the blood before they become a risk.

"I did have a headache at one stage but that may just have been the hospital environment," says Ms Farmer. "I had complete trust in the medical people."

The challenge-model research has attracted support from Medicines for Malaria Venture (MMV), a Switzerland-based non-profit agency. A big international donor will shortly be announced by the institute.

Tim Wells, chief scientific officer at MMV, says: "QIMR learns lots about the basic immunology of malaria - it's a valuable resource, and . . . James's [Prof McCarthy's] team has learnt a lot about how the human body deals with low levels of infection."

MMV and pharmaceutical company partners provide the new drug compounds, which are tested by QIMR. It now has three molecules moving into full clinical development - and MMV picked the dose to be applied for two of the drugs based on data provided by the QIMR team.

"It saved us a year at least, which is important knowing that we urgently need new treatments," says Mr Wells. "We know really early on in a project if it works. That gives us the confidence to move quickly into the big clinical studies in Africa, which are expensive and also complicated."

The "silver bullet" for researchers is the development of a 90-100 per cent effective vaccine for malaria. The current vaccine in phase III trials is expected to be only 30-50 per cent protective. Groups working on vaccines are making progress and the data provided by the challenge model are building knowledge on how one should work.

"Too often people prefer to fund big "pivotal" clinical trials based on not enough science," says Mr Wells. "But what is important is that we understand the human biology of the vaccines before we start doing big clinical trials."

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