Kevin McCoy

USA TODAY

Shares of Tekmira Pharmaceuticals soared Friday after the Canada-based firm said the U.S. Food and Drug Administration had allowed potential use of the company's experimental Ebola drug to treat those infected with the deadly virus.

The stock closed up more than 45% at $20.70 on a day when the World Health Organization said the Ebola outbreak that's spreading across West Africa is a "public health emergency of international concern."

The FDA gave verbal approval to change the status on the drug, known as TKM-Ebola Investigational New Drug Application, from a full clinical hold to a partial clinical hold. The action may allow the medicine to be used to treat the growing tally of those stricken by the Ebola virus.

"We are pleased that the FDA has considered the risk-reward of TKM-Ebola for infected patients. We have been closely watching the Ebola virus outbreak and its consequences, and we are willing to assist with any responsible use of TKM-Ebola. The foresight shown by the FDA removes one potential roadblock to doing so," said Dr. Mark Murray, CEO of Tekmira Pharmaceuticals.

"This current outbreak underscores the critical need for effective therapeutic agents to treat the Ebola virus," added Murray."We recognize the heightened urgency of this situation, and are carefully evaluating options for use of our investigational drug within accepted clinical and regulatory protocols."

The outbreak, the largest and longest in history, has killed 961 people and sickened 1,779 others, new data issued by WHO showed Friday. It's on track to sicken more than all of the previous Ebola outbreaks combined.

Located in Vancouver, Tekmira focuses its research on RNA interference, a technique that has the potential to take advantage of the body's natural processes to turn off genes. The company says the process may help "treat serious human diseases that often rely on the production of certain proteins at the genetic level."

In May 2010, results of pre-clinical studies that showed the Tekmira medication's ability to protect non-human primates from the disease were published in the medical publication The Lancet. The studies were done in collaboration with infectious disease researchers from Boston University and the United States Army Medical Research Institute for Infectious Diseases, Tekmira said.

The study results showed the medication targeted the Ebola virus to treat previously infected non-human primates, with 100% protection from an otherwise lethal dosage, the company said.

Tekmira started a Phase I clinical trial on human patients in January. The trial, the normal first step in the FDA approval process, is designed to test the safety, tolerability and effectiveness of newly developed medications.

In March, the FDA approved fast-track designation of the Tekmira research. That designation is designed to speed drug development, expedite the regulatory agency's review and get new therapies to patients more quickly.