Preliminary results of Phase 3 clinical trial, which is still underway, on RTS,S, an experimental malaria vaccine, showed that it reduces malaria risk in babies aged 5 to 17 months by half. The results have been published in NEJM (New England Journal of Medicine. Malaria kills nearly 800,000 people annually, the majority of whom are children under five years of age in sub-Saharan Africa.

The authors write that the vaccine provides significant protection against clinical and severe malaria, while at the same time its tolerability and safety profile is acceptable.

The interim trial results were presented today at the Malaria Forum, which is being hosted by the Bill and Melinda Gates Foundation, Seattle, Washington.

The human study took place in seven different sub-Saharan African countries at 11 sites. It demonstrated that three doses of RTS,S lowered a child’s risk of developing clinical malaria by 56% and severe malaria by 47%.

These data were gathered from monitoring the first 6,000 children over a twelve month period after being vaccinated. The children were aged from 5 to 17 months.

Clinical malaria commonly leads to chills and high fevers. A common complication of clinical malaria is severe malaria, which can have serious effects on the patient’s brain, kidney and blood – severe malaria is life-threatening.

The researchers announced that the initial Phase 3 results are in line with those from the results in Phase 2 trials.

This experimental vaccine can provide further protection, on top of the widespread coverage of insecticide-treated bed nets and current malaria medications.

A number of infants aged between 6 and 12 weeks are being vaccinated as part of this ongoing trial. Results are expected before the end of 2012. The final results of the trial will provide a better understanding of RTS,S for infants, for clinical as well as severe malaria.

Scientists have carried out an analysis of severe malaria episodes so far in all the 15,460 children in the trial – aged from 6 weeks to 17 months. The researchers wrote that “This analysis showed 35% efficacy over a follow-up period ranging between 0 and 22 months (average 11.5 months). ”

The RTS,S vaccine is still an experimental drug. By the end of 2014 there should be data on its efficacy 30 months after the administration of the third dose. Then international public health organizations, regulatory bodies and national public health services will have evidence they can use to evaluate the vaccine’s potential benefits.

22% of those receiving a control vaccine experienced a serious adverse event (SAE), compared to 18% of those given RTS,S. The rates of seizures and meningitis were higher in the malaria group. The researchers believe the cases of meningitis were not related to the vaccine, while seizures were linked to fever. More details regarding adverse events will be published over the next three years.

A principal trial investigator, Tsiri Agbenyega, who is also Chair of the Clinical Trials Partnership Committee, said:

“The publication of the first results in children aged 5 to 17 months marks an important milestone in the development of RTS,S. These results confirm findings from previous Phase II studies and support ongoing efforts to advance the development of this malaria vaccine candidate. Having worked in malaria research for more than 25 years, I can attest to how difficult making progress against this disease has been.

Sadly, many have resigned themselves to malaria being a fact of life in Africa. This need not be the case. Renewed interest in malaria by the international community, and scientific evidence such as that we are reporting today, should bring new hope that malaria can be controlled.”

CEO of GlaxoSmithkline, makers and co-developers of the experimental vaccine, Andrew Witty, CEO, GSK, said:

“These data bring us to the cusp of having the world’s first malaria vaccine, which has the potential to significantly improve the outlook for children living in malaria endemic regions across Africa. The addition of a malaria vaccine to existing control interventions such as bed nets and insecticide spraying could potentially help prevent millions of cases of this debilitating disease. It could also reduce the burden on hospital services, freeing up much needed beds to treat other patients who often live in remote villages, with little or no access to healthcare.

Today’s results are a testament to the dedication and tenacity of many scientists, led at GSK by Jean Stéphenne and his vaccine team, including Joe Cohen, the co-inventor of RTS,S, in partnership with many others from across the world. Development is however only half the task, but GSK remains committed to further research into malaria and most importantly, to ensuring that this vaccine will reach those who need it.”

President and CEO of PATH Christopher Elias, said:

“This trial represents a powerful example of the high-quality science that is moving us toward controlling and someday potentially eliminating malaria. The results made public today are encouraging and certainly something to feel good about, but let’s also remember the human dimension. The PATH Malaria Vaccine Initiative’s mission is to deliver a vaccine to the children of Africa so that instead of carrying near lifeless babies to crowded pediatric wards, mothers will carry their infants past noisy school playgrounds to bustling immunization clinics.

Today, we are an important step closer to realizing that vision, and we look forward to continuing our drive, together with our partners, to bring this vaccine home to the children of Africa.”

Co-chair of the Bill & Melinda Gates Foundation Bill Gates, said:

“A vaccine is the simplest, most cost-effective way to save lives. These results demonstrate the power of working with partners to create a malaria vaccine that has the potential to protect millions of children from this devastating disease.”

RTS,S is a joint venture between GSK and the PATH MVI (Malaria Vaccine Initiative), alongside top research centers in Africa. The Clinical Trials Partnership Committee has representatives from all the partners. The vaccine’s clinical development was funded by the Bill & Melinda Gates Foundation. European, North American and African scientists continue working on the development of RTS,S.

If or when the vaccine is approved by regulatory agencies and certified by WHO (World Health Organization), it will be administered to African children. This vaccine, when added to the already impressive array of measure to combat malaria, including anti-malarial medications and bed nets, will represent an important step forward toward sustained malaria control.

In a communiqué today, the GAVI Alliance wrote:

“These promising results demonstrate the power of product development public-private partnerships to tackle global challenges. GAVI commends the efforts of its partners, the Malaria Vaccine Initiative at PATH and GlaxoSmithKline and the dedication of the entire malaria community including the 11 African research centers currently conducting the trial. “

The US CDC (Centers for Disease Control and Prevention) today wrote:

“The Centers for Disease Control and Prevention welcomes the announcement today that results from the clinical trial in Africa of a malaria vaccine candidate show it prevented about half of malaria cases, including the most severe, in young children.”

Written by Christian Nordqvist