ZMapp seems to be working against Ebola Virus

There was some good news last week on the fight against Ebola Virus Disease (EVD). Two American patients who were flown from Liberia to Emory University Hospital were released yesterday. Both patients had received treatment from a new experimental drug named ZMapp while in Africa. According to an account from Dr. Sanjay Gupta from CNN, the drug had a miraculous effect on at least one of the two; I was initially a bit more cautious in my interpretation.

ZMapp is a cocktail of three monoclonal antibodies that are targeted against Ebola virus (EV) proteins. Injecting these antibodies into the blood is like giving the patient an "antiserum"; the antibodies can bind to the virus, preventing it from infecting cells and facilitating its destruction by immune cells.

Happily as reported in The New York Times, the two Americans have made a complete recovery; no virus has been detected in their blood, and so there is no longer any danger to themselves or others:

"Dr. Ribner said that there was no virus in their blood and that they no longer had any symptoms. “We are confident they pose no public health threat,” he said. Virus has been found in the semen of men who recovered from Ebola as long as three months after recovery. But the disease has never been proven to have been transmitted through sex. The C.D.C. suggests that men who have recovered use condoms temporarily, and Dr. Brantly was informed of the C.D.C.’s recommendation, Dr. Ribner said."

Why hasn't ZMapp been given to African patients? The problem is ZMapp is in extremely short supply. It is an experimental drug that has not been officially (i.e. FDA) approved, and is currently being manufactured by a novel process (grown in tobacco leaves).

The manufacturer of ZMapp, Mapp Pharmaceuticals, has scraped together 12 more doses of the drug and sent it to Liberia. In more good news, some of these doses have been given to three more patients and at least two have shown improvement (LATimes):

"In a statement, the international health agency said that doctors working in Liberia told them a doctor and nurse have shown “marked improvement” after receiving the experimental treatment ZMapp."

Because the drug has not been administered under the carefully controlled conditions of a clinical trial (i.e comparing ZMapp patients to control patients who receive a placebo), one cannot be certain about the extent of the medical effect of ZMapp. The "cures" could be due in part to a placebo effect, or from the fact that patients who have received ZMapp have received better overall care. On the other hand, given the very high fatality rate of EVD (estimated to be around 70%), the fact that a significant fraction of the patients who have received ZMapp have improved and even fully recovered is very encouraging.

There are other anti-Ebola drugs being developed that will be sent to Africa, and clinical trials of a promising Ebola virus vaccine are being expedited. Optimistically, I predict that this latest large outbreak of Ebola virus will be the last.

Figure 1. Former Ebola patient Dr. Kent Brantly was released from Emory University Hospital this week fully recovered from Ebola Virus Disease (NYTimes photo).