November 26, 2014

expert reaction to preliminary results from phase I trial of chimpanzee adenovirus vector Ebola vaccine (cAd3-EBO)

Researchers writing in the New England Journal of Medicine have discussed their finding from a phase I clinical trial using an Ebola vaccine derived from a chimpanzee adenovirus. The trial used twenty healthy adults, and the research group report no safety concerns.

Prof Adrian Hill, Director of Jenner Institute, University of Oxford, and lead investigator of a UK safety trial of the GSK/NIH Ebola vaccine said:

“These results on the safety of the chimpanzee adenovirus vaccine are very reassuring and the NIH team are to be congratulated on providing results so quickly. The immune responses reported suggest that the vaccine formulation to be used in West Africa should also be immunogenic. We will know about that vaccine soon as over 200 people have now been immunised. When we have these data in December it should be possible to decide on the most suitable dose to use and whether a booster dose will be needed in the West African efficacy trials”.

Dr Jeremy Farrar, Director of the Wellcome Trust, said:

“This work is encouraging and another significant contribution to efforts to tackle the Ebola crisis. We need a variety of public health interventions if we are to impact on this and future outbreaks, and that must include vaccines. It is why we and our international partners are supporting accelerated development of several vaccine candidates, including this one, at the same time. We had more good news this week about another of these vaccines – rVSV-EBOV – with the announcement that Merck have struck a deal to scale up production and take it through clinical trials. It’s important that this momentum is maintained and that these vaccines can move to being tested in countries affected by the epidemic as soon as possible.”

Prof Jonathan Ball, Professor of Molecular Virology, University of Nottingham, said:

“We’ve been eagerly awaiting data from the first clinical trials of the Ebola virus vaccines and initial findings look promising.

“The trial was primarily to find out if the chimpanzee adenovirus-based vaccine is safe when administered to humans and, apart from some minor adverse effects in some patients at the higher doses, the vaccine was well tolerated.

“The data also shows that this higher dose was able to elicit immune responses that were comparable to those seen in monkeys immunised with the same vaccine. Importantly these monkeys were protected, albeit short-term, from subsequent challenge with Ebolavirus.

“Data from trials being carried out in Africa will be key to see if the vaccine has a similar profile in populations most at risk from Ebolavirus.

“Of course we don’t know if the immunity seen in vaccinated people is protective, nor if the other vaccines in development will perform better. This is what phase II trials will tell us and the design and roll-out of these will be the next key issue to resolve.”

‘Chimpanzee adenovirus vector Ebola vaccine- preliminary report’ by Ledgerwood et al. published in New England Journal of Medicineon Wednesday 26th November. 

All our previous output on this subject can be seen at this weblink: http://www.sciencemediacentre.org/ebola-outbreak/

Declared interests

Prof Adrian Hill is running the UK trial for the GSK/NIH adenovirus Ebola vaccine.

Dr Jeremy Farrar is director of the Wellcome Trust, which is co-funding trials of the GSK/NIH adenovirus Ebola vaccine (cAd3-ZEBOV) and the VSV Ebola vaccine (rVSV-EBOV) in the UK and West Africa. Jeremy is also on the editorial board of NEJM.

Prof Jonathan Ball: No interests declared