A drug once thought to be the best candidate for an Ebola treatment didn't work on patients in Sierra Leone. The manufacturer, Tekmira, has halted its human trials because the treatment is "not likely to demonstrate an overall therapeutic benefit."

The drug, TKM-Ebola, has had a bumpy ride getting to Africa for testing. After showing a 100 percent success rate treating primates infected with the virus, the drug was fast-tracked by the US Food and Drug Administration last year to quickly get it into human clinical trials. In July, the FDA stopped this expedited process because the agency wanted more information on higher doses of the drug. In August, the FDA finally gave Tekmira the go-ahead to test the drug on people already infected with the virus.

The treatment is "not likely to demonstrate an overall therapeutic benefit"

Some scientists have questioned the company’s research methods for the drug, since the study did not have a control group; all of the patients involved received the experimental drug, and no one received a placebo. Scientists have argued that this set up would make it harder to know whether or not the drug was effective.

Tekmira says it will make data from the trial available as soon as possible, once analyses are finished.