Editor's note: This story was updated on Nov. 4, 2014, with information about an inhaled vaccine in development as well as new research on an interferon drug.
Oct. 3, 2014-- As the number of Ebola cases continues to grow, people around the world are eager for a treatment or vaccine that could trump the deadly infection.
But only one of the three drugs that have been used to treat people with Ebola, TKM-Ebola, has even begun testing in humans -- although that’s on hold because of safety concerns. Meanwhile, a trial in healthy volunteers of a fourth drug, which has not yet been given to Ebola patients, found that the volunteers had few side effects, and they were okay after taking it.
Of the promising vaccines on the horizon, two are being tested for safely in volunteers.
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“Today we know the best way to prevent the spread of Ebola infection is through public health measures, including good infection-control practices, isolation, contact tracing, quarantine, and provision of personal protective equipment,” says Anthony Fauci, MD. He's the director of the National Institute of Allergy and Infectious Diseases (NIAID). “However, a vaccine will ultimately be an important tool in the prevention effort.”
Here is a roundup of some of the Ebola treatments and vaccines in the research pipeline:
NIAID/GSK investigational Ebola vaccine: The first safety tests of this vaccine, developed by scientists at the NIAID and GlaxoSmithKline, began in September in healthy volunteers at the NIH Clinical Center in Bethesda, MD, and in Great Britain. GSK says it will have 15,000 doses available in December, when field testing in Liberia is expected to begin, Peter Jahrling, PhD, chief scientist at the NIAID Integrated Research Facility, said at an Ebola forum on Oct. 14 at the Johns Hopkins Bloomberg School of Public Health.
Two variations of the vaccine will be tested. Both use a chimp cold virus to deliver segments of the Ebola gene into the volunteers’ cells. The cells take the segment and produce an Ebola marker on its surface. A volunteer’s immune system sees the marker and attacks. One version of the vaccine uses genetic segments from Zaire Ebola, the virus species causing the current outbreak, and Sudan Ebola. The other version uses only Zaire Ebola genetic material. The vaccines cannot cause Ebola.
VSV-EBOV vaccine: The FDA in September gave NewLink Genetics Corp. permission to begin the first clinical trials to test the company’s Ebola vaccine, which was developed by Canada’s Public Health Agency. In a statement Oct. 22, the NIH said human testing was underway at its clinical center in Bethesda, MD, where adults get two doses. The Walter Reed Army Institute of Research in Silver Spring, MD, is testing the vaccine as a single dose, according to the NIH.
The vaccine uses a weakened animal virus to deliver Ebola proteins to the person, triggering an immune response. The vaccine can't cause a person to become infected with Ebola, the NIH said.
NewLink spokesman Brian Wiley said Oct. 2 that other trials will open soon around the globe.
Profectus BioSciences vaccine: The Office of the Assistant Secretary for Preparedness and Response, part of the Department of Health and Human Services, will provide about $5.8 million, as well as expertise and technical assistance, to further develop the vaccine created by the Baltimore company.
The vaccine uses a weakened version of a virus called vesicular stomatitis virus, or VSV, that does not make people sick. A molecule from the surface of the Ebola virus is inserted into the weakened VSV. After the vaccine is injected, the VSV carries the Ebola molecule to cells, which then begin to pump it out, triggering an immune response. A single dose of the Profectus BioSciences vaccine has been shown to protect macaque monkeys against Ebola and Marburg viruses, both of which cause hemorrhagic fever.
Inhaled vaccine: Researchers at the University of Texas at Austin’s College of Pharmacy have found an inhaled Ebola vaccine works well in monkeys. Their findings were published Nov. 1 and were being presented at the annual meeting of the American Association of Pharmaceutical Sciences.
The survival rate in Ebola-infected monkeys was 100% 150 days after they received the inhaled vaccine, researchers said.
The next step is testing the inhaled vaccine in people, according to a university news release.
BCX4430: This antiviral drug is effective against more than 20 viruses, including Ebola. It was developed by BioCryst Pharmaceuticals, Inc., a company in Research Triangle Park, N.C. Under a 5-year contract awarded in September 2013 -- before the current Ebola outbreak -- the NIAID will provide up to $26.3 million to BioCryst to speed the development of BCX4430 for the treatment of Ebola, with the first safety trials expected to begin later this year or early next year, according to the NIH. In animal trials, the drug was 100% effective against Marburg, but it was somewhat less effective against Ebola, Jahrling said.
TKM-Ebola: This drug stops the Ebola virus from multiplying. So far, the only people who have received it are people infected with the Ebola virus, along with people who participated in a trial that was put on hold after 6 months.
In a Sept. 22 statement , Mark Murray, PhD, president and CEO of Tekmira Pharmaceuticals in Vancouver, said “several” Ebola patients had received his company’s drug under emergency protocols set up with the FDA and Health Canada. But, Murray said, that “does not constitute controlled clinical trials.”
An early-stage safety trial of TKM-Ebola began in January in healthy volunteers, but Tekmira announced in early July that the FDA had put the trial on hold until safety concerns were resolved. On Aug. 7, though, Tekmira said the FDA had changed the full hold placed on its Ebola drug to a “partial hold.” That action enabled the use of TKM-Ebola, shown to be 100% effective in treating Ebola-infected monkeys, to treat people infected with Ebola. Jahrling said he expects the safety trial will resume with a lower dose of the drug.
One of the people treated with TKM-Ebola was Rick Sacra, MD, an American doctor who became infected with Ebola while working in Liberia, according to Chris Kratochvil, MD, associate vice chancellor for clinical research at the University of Nebraska Medical Center. Sacra was hospitalized for 3 weeks at The Nebraska Medical Center, the University of Nebraska’s teaching hospital in Omaha. He was released Sept. 25 after repeated blood tests showed that he was free of the virus.
Sacra received a daily infusion of TKM-Ebola for 7 days, Kratochvil tells WebMD. “We don’t know yet what the appropriate dose is because we don’t even know yet if the medication works,” Kratochvil says. “This was really based on some animal studies.”
He said “it is really difficult to say” whether TKM-Ebola or other care that Sacra received deserves credit for his recovery. One of the benefits of giving an untested drug such as TKM-Ebola to a patient is “we can get a sense of tolerability,” Kratochvil says. “We collected data throughout the treatment process that they (Tekmira) in turn will give to the FDA.” Still, he says, “the critical thing is that we get some structured clinical trials started.”
ZMapp: Identified only this past January, ZMapp is a cocktail of three antibodies made in tobacco plants.Seven Ebola patients have been treated with ZMapp, and two of them died.
The drug has been 100% effective in experimentally infected monkeys, even after they get a fever, Jahrling said.
The first two patients treated with ZMapp were Kent Brantly, MD, and Nancy Writebol, two American medical missionaries who received the drug while hospitalized in Liberia. Brantly and Writebol were then flown to the U.S., where in August they were hospitalized at Emory University Hospital in Atlanta. Both recovered and were released.
Shortly after Brantly and Writebol were treated with ZMapp, Mapp Pharmaceuticals announced that the available supply had been exhausted. “We have complied with every request for ZMapp that had the necessary legal/regulatory authorization,” the company said in a statement Aug. 12.
On Oct. 2, a Department of Health and Human Services official told WebMD that the agency “is exploring a variety of options to expand production of ZMapp, including working with Caliber (Caliber Biotherapeutics, a Texas company) and other producers of tobacco-based pharmaceuticals.”
Jahrling said the company expects to have 12 to 20 doses -- “a drop in the bucket” -- available by December.
Brincidofovir (CMX001): On Oct. 6, the FDA OKd emergency use of this antiviral drug for people with Ebola -- specifically for a Liberian national, Thomas Eric Duncan, who was being treated at Texas Health Presbyterian Hospital in Dallas. Duncan died Oct. 8.
Ashoka Mukpo, a freelance cameraman who was infected while covering the Ebola outbreak in West Africa for NBC, also received brincidofovir while being treated at The Nebraska Medical Center. Mukpo recovered and was released from the hospital Oct. 22.
The drug works by keeping viruses from multiplying. Brincidofovir is being tested in clinical trials for effectiveness against cytomegalovirus and adenovirus, but it's been given to patients with “many other life-threatening viral infections” through an expanded access trial that began in 2012, according to drugmaker Chimerix Inc. It was created to treat smallpox in case of a bioterrorism threat or accidental release.
Test-tube experiments done at the CDC and the NIH reveal the drug showed effectiveness against Ebola, similar to that seen in testing of the drug against adenovirus and smallpox, according to the company.
Jahrling said enough brincidofovir is available for as many 3,500 courses of treatment. NIAID plans to test the drug in guinea pigs, Jahrling said.
AVI 7537: On Oct. 16, Sarepta Therapeutics, a Cambridge, MA, company, announced it had published the results of a trial that found that human volunteers were okay after taking the drug. It has not yet been given to any Ebola patients, but it has been shown to be effective in protecting 60% to 80% non-human primates when treatment started an hour after they were infected, Jahrling said. Up to 24 treatment courses could be made available soon, he said.
Repurposed approved drugs: Another treatment option would be off-label use of medications that have already been approved for other conditions. “We’re cranking through them,” Jahrling said, ticking off interferons, used to treat certain cancers, hepatitis C, multiple sclerosis, and genital warts; anti-parasitic drugs; anti-inflammatory medications; and ion channel inhibitors, the best-known of which are calcium channel blockers used to treat high blood pressure. Two anti-HIV medications, AZT and 3TC, had been suggested as possible Ebola treatments, but Jahrling said they “are off the table” because they didn’t have an anti-Ebola effect.
One interferon treatment, called Alferon, was found by researchers at the U.S. Army Medical Research Institute of Infectious Diseases to protect human cells against Ebola, drug-maker Hemispherx Biopharma said in a statement Nov. 3. The drug is approved to treat genital warts caused by human papillomavirus (HPV). But, the drug maker said, clinical trials must be done to measure the drug’s effect in humans.
Blood transfusions from Ebola survivors: Besides TKM-Ebola and intensive care, Sacra received a transfusion of Brantly’s blood, Kratochvil said. Brantly himself had received blood from a 14-year-old boy he had treated for Ebola who recovered.
Mukpo and Nina Pham, a 26-year-old nurse at Texas Health Presbyterian Hospital who became infected after treating Duncan, also received blood from Brantly. Pham also recovered and was released from the National Institutes of Health in Bethesda, MD.
The thought behind this treatment is that blood from people who recovered from Ebola contains antibodies that could help recipients fight the virus.
Last month, at a World Health Organization conference to discuss potential Ebola treatments and vaccines, experts agreed to give further research into the use of whole blood or plasma from recovered patients a top priority. This approach was first used in 1976, the year Ebola first emerged, but that patient died within days. During the 1995 Ebola outbreak in the Democratic Republic of Congo, whole blood from people who’d recovered from the disease was given to eight patients, and seven survived. The WHO also issued a guidance document about this treatment for national health authorities and blood transfusion services in affected countries.