By Dennis Thompson
The new pill, which targets the genetics of influenza viruses, has shown that it can reduce fever and respiratory symptoms in lab animals, as well as reducing the overall amount of virus in their bodies, researchers report.
Preparations are underway for human trials of the "next-generation" drug, EIDD-2801, said senior researcher Richard Plemper, a professor with the Institute of Biomedical Sciences at Georgia State University.
Several antiviral drugs already are on the market for influenza, the most widely known of which is Tamiflu.
The new drug appears to have one significant advantage over them, Plemper said -- it seems to block attempts by the wily flu virus to mutate and become drug-resistant.
"Because the virus mutates rapidly, that's the problem with existing influenza medications, viral resistance emerges rapidly," Plemper said. "The virus has not found a route of escape with this drug. We did not see any mutations coming up and then taking over."
Each year, flu causes between 30,000 and 80,000 deaths in the United States, researchers said in background notes.
The flu vaccine is effective but can only directly protect against a handful of strains predicted to be the most likely to circulate in a given year. Meanwhile, existing antivirals are coming up against new flu strains that have developed resistance.
EIDD-2801 works by targeting an enzyme needed to replicate the genetics of the influenza virus, Plemper said.
The drug tricks the virus into making genetic errors as it replicates, creating essential flaws that doom its ability to spread, he said.
"The drug mutates the virus to death, forcing the virus to make so many errors that the virus cannot live any longer," Plemper explained.
Testing in ferrets -- an animal in which flu infection tracks with that of humans -- showed that the drug caused the animals' viral load to drop by more than four orders of magnitude within 24 hours of the first dose.
The duration of fever also was significantly shorter in treated ferrets, compared with infected ferrets who didn't receive the drug.
Results from animal studies may not always have the same results in humans. But further laboratory tests showed that the drug was effective in treating human cells cultured from the respiratory system, Plemper added.
"These are disease-relevant tissues," Plemper said. "These are the human cells where we want to treat the infection. This is where we want to go after the virus with the drug."
Dr. Amesh Adalja, a senior scholar with the Johns Hopkins Center for Health Security in Baltimore, said the new drug could be an "important addition" that would "increase our resilience against both seasonal and pandemic influenza." He was not involved with the study.
"Antiviral therapy can be lifesaving but is often underutilized and, in some cases, limited by resistance," Adalja said. "For example, the first class of influenza antivirals -- the adamantanes -- are virtually obsolete because of widespread antiviral resistance."
Phase 1 human safety trials of EIDD-2801 could potentially get underway as early as next spring or summer, Plemper said. That work will be conducted by the Emory University Institute for Drug Development in Atlanta.
The new study was published Oct. 23 in the journal Science Translational Medicine.