Progress towards Ebola treatment
have taken an important step towards a possible treatment strategy
for the Ebola virus.
Haemorrhagic fever from the Ebola virus is fatal in up to 80 per cent of cases in humans. The virus is thought to cause excessive blood coagulation and thrombosis leading to organ dysfunction. Inhibition of the blood coagulation pathway could therefore be a potential therapeutic approach for Ebola treatment.
An outbreak in the Republic of Congo in November has already claimed around 30 lives and another case in 2002 killed more than 100. There is currently no treatment for the disease apart from supportive care, trying to keep patients alive long enough for the infection to run its course.
In the latest study, Thomas Geisbert and colleagues from the US Army Medical Research Institute of Infectious Diseases and colleagues injected 12 rhesus macaques with the virus to induce Ebola haemorrhagic fever. Nine of the macaques received an inhibitor of the blood coagulation pathway developed by US company Corvas, called recombinant nematode anticoagulant protein c2 (rNAPc2), while three macaques received the Ebola virus only.
Treatment with rNAPc2 prolonged survival time and resulted in a 33 per cent survival rate; this contrasted with macaques in the control group, of whom all except one died during the study period (since the study was completed the remaining control animal has also died).
The surviving macaques in the treatment group were in good health nine months after the study. In addition, survival was longer (12 days) for treated macaques who died compared with untreated macaques in the control group (eight days). The results are published in The Lancet (December 13).
Geisbert commented that the study provides the first evidence of a possible treatment for not only Ebola, but also other viral haemorrhagic fevers.
"Our results have great clinical implications, since our treatment approach of Ebola haemorrhagic fever targets the disease process rather than replication of the infectious agent," he said.
Importantly, rNAPc2 has already been shown to have a suitable pharmacokinetic and safety profile in humans. Corvas, which was recently acquired by fellow US firm Dendreon, has already taken rNAPc2 into Phase II clinical trials in patients with acute coronary syndrome, including unstable angina and a mild form (non-ST segment elevation) of myocardial infarction.
