The 2014 – 2016 Ebola outbreak was the largest in history. It began with a few cases in Guinea, but quickly spread to Liberia and Sierra Leone, with some limited cases occurring in other countries. The outbreak grew so serious that the World Health Organization (WHO) declared it a public health emergency of international concern1. However, even with international assistance, the disease was hard to combat. Preventing the spread of Ebola virus disease was difficult due to the lack of vaccines and the ease of transmission of the virus2. Treating it was no easier. At the start of the outbreak, there were no approved treatments for Ebola virus disease3. As the crisis continued, some treatments were developed, but they still needed to be tested for safety and efficacy.
One of the most promising drugs that was developed is called ZMapp. ZMapp is made up of three monoclonal antibodies. These antibodies are produced by putting antibody genes into tobacco plants. When the drug is given to a patient, the antibodies in ZMapp bind to the virus and neutralize it – that is, they prevent the virus from affecting human cells4.
ZMapp was first tested in monkeys, where it was shown to be safe and effective. After that, the drug was tested in a randomized, controlled trial in human patients with Ebola virus disease. In the trial, the patients were separated into two groups – one group received only standard care, while the other group received both standard care and ZMapp5. If more patients survived in the group that received ZMapp, it would show that the drug was more effective than just receiving standard care.
In the group that received only standard care, 37% of the patients died, while just 22% of the patients died in the group that received standard care and ZMapp. This result suggests that there is a benefit to receiving ZMapp; however, it has not been proven that ZMapp is effective. The drug did not reach the statistical threshold that proves its effectiveness. Moreover, only a small number of patients were used in the trial. Because of these two points, the results can only be viewed as suggestive, not conclusive5.
The trial also suggests that ZMapp is safe. ZMapp is delivered directly into the patient’s bloodstream in three separate infusions. Side effects of ZMapp were most common with the first infusion, but decreased with each subsequent infusion. The most common side effects were fever and hypotension. Only one serious side effect throughout the course of the trial was thought to be caused by the infusion of ZMapp5.
Though the results of the trial are not conclusive, they do suggest that ZMapp is both safe and provides a benefit to patients who receive it. When the next outbreak of Ebola virus disease occurs, perhaps ZMapp could help to save lives.
You can read the original research article this post is based off for free here.
1: Ebola (Ebola virus disease): 2014 Ebola outbreak in West Africa [Internet]. 2016. Atlanta (GA): Centers for Disease Control and Prevention; [cited 2016 Oct 23]. Available from https://www.cdc.gov/vhf/ebola/outbreaks/2014-west-africa/
2: Ebola (Ebola virus disease): Prevention [Internet]. 2015. Atlanta (GA): Centers for Disease Control and Prevention; [cited 2016 Oct 23]. Available from https://www.cdc.gov/vhf/ebola/prevention/index.html
3: Ebola (Ebola virus disease): Treatment [Internet]. 2015. Atlanta (GA): Centers for Disease Control and Prevention; [cited 2016 Oct 23]. Available from https://www.cdc.gov/vhf/ebola/treatment/index.html
4: ZMapp FAQ [Internet]. 2015. San Diego (CA): Mapp Biopharmaceutical; [cited 2016 Oct 23]. Available from http://mappbio.com/zmapp-faq/
5: Davey Jr RT, Dodd L, Proschan MA, Neaton J, Neuhaus Nordwall J, Koopmeiners JS, Beigel J, Tierney J, Clifford Lane H, Fauci AS, et al. 2016. A randomized, controlled trial of ZMapp for Ebola virus infection. New Engl J Med. 375:1448-56.