Burnaby-based company halts clinical trials of Ebola drug
Hopes of a treatment being developed in the near future now rest on antibody cocktail created in Winnipeg
TORONTO — A clinical trial of what was once thought to be one of the brightest hopes for an Ebola drug has been halted after an interim assessment concluded there was no sign the experimental product was offering overall benefit.
Tekmira Pharmaceuticals announced Friday that the Phase 2 trial of its TKM-Ebola drug had been stopped in Sierra Leone. The announcement leaves the drug in limbo.
Tekmira offered no comment on whether it plans to continue to develop the Ebola drug and a sister compound designed to fight infection with Marburg fever, a disease similar to Ebola. The Burnaby-based company did not respond to a request for an interview.
Asked by email if the drug should be shelved as an Ebola therapeutic, principal investigator Dr. Peter Horby replied: “It is too soon to say, really.”
A scientist who has researched the drug in non-human primates expressed concern about the development, worrying the decision might scupper a drug he believes shows a lot of promise.
“Knowing the mechanism of how the drug works, looking at all the non-human primate data we have, it’s hard for me to believe that the drug would not be beneficial if used under the right circumstance,” said Tom Geisbert, an Ebola virus expert at the University of Texas Medical Branch in Galveston. Geisbert does not have a financial interest in the drug.
He noted an improved version of the drug he and others tested in primates late last year showed greater success than the version that was being used in the trial in Sierra Leone.
Geisbert said if TKM-Ebola is shelved, the hopes for Ebola treatment will rest almost entirely on one drug, ZMapp — the antibody cocktail created at Canada’s National Microbiology Laboratory in Winnipeg based on antibodies created there and at the U.S. Army Medical Research Institute of Infectious Diseases in Frederick, Md.
“I can tell you (from) all the monkey studies that we do, you’ve got ZMapp and this one. And there’s a gigantic gap between those two drugs in monkeys and everything else. ... You’re dropping off a cliff to the next thing down,” Geisbert said.
Clinical trials are designed with built-in triggers which, if reached, require the research team to pause and re- evaluate. This trial reached one and the conclusion was “continuing enrolment was not likely to demonstrate an overall therapeutic benefit,” the Tekmira press release said.
It is not clear how many patients had been enrolled in the trial by the time it was stopped. It was originally designed to test the drug on 100 Ebola patients.
Testing was unusual. Instead of randomly assigning people to either get the drug or standard treatment, Patients who were given the drug were compared with previous Ebola patients.