FDA relaxes restrictions on Ebola drug

A block on clinical testing of a drug for Ebola developed by Tekmira Pharmaceuticals has been downgraded in the face of the ongoing outbreak of the disease.

With the World Health Organization (WHO) now declaring the spread of Ebola in West Africa an international health emergency following the deaths of 930 people, it seems the US Food and Drug Administration (FDA) is considering limited access to Tekmira’s TKM-Ebola as a precaution.

Last month, the agency placed a clinical hold on TKM-Ebola – an RNA interference (RNAi) or gene silencing drug which was in a phase I trial – and asked for more data from Tekmira on the drug’s safety profile. Now, it has downgraded the block to a partial clinical hold which could allow it to be used in people infected with the virus.

The news comes as the WHO has itself convened a meeting next week to examine the medical ethics of using untested drugs and vaccines in the context of a public health crisis, after two health workers were given the an experimental antibody cocktail in development at US company Mapp Biopharmaceuticals.

Latest reports suggest the passive immunity provided by the ZMapp drug may be having an effect, with the two victims showing some signs of recovery.

Tekmira said in a statement yesterday that the FDA has “verbally confirmed” the reduced restrictions on TKM-Ebola, adding that the company was poised “to assist with any responsible use” of the drug.

“The foresight shown by the FDA removes one potential roadblock to doing so,” said Mark Murray, the Vancouver-based company’s chief executive and president.

The FDA placed TKM-Ebola under clinical hold in order to look more closely at the mechanism behind cytokine release observed at higher doses of the drug, and also to request a change to the protocol of the Phase I trial “designed to ensure the safety of healthy volunteer subjects.”

The drug is being developed under a $140 million contract with the US Department of Defense and showed 100 per cent protection from an otherwise lethal dose of Ebola in primate studies.

The FDA’s decision on TKM-Ebola raises the prospect of other early-stage therapies for the virus being used in people infected during the current outbreak. These include Sarepta Therapeutics’ AVI-7537, another RNAi treatment in volunteer trials, as well as MediVector’s favipiravir which is being developed for influenza but could also be beneficial against Ebola.

The US National Institutes of Health (NIH) has also suggested it will accelerate human trials of a vaccine against Ebola to September amid concerns about the spread of the disease.

Ebola is spread by close contact and can take between two and 21 days to incubate. It causes high fever, bleeding and central nervous system damage and has a fatality rate of up to 90 per cent. Fruit bats are considered to be the virus’ natural host.

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