BioCryst surges on hopes for intravenous anti-viral

With news of the flu pandemic never far from the headlines investors have been quick to jump on companies that might benefit from demand for their products. Today, the attention fell on BioCryst, following the release of positive phase III data on the company’s antiviral peramivir, announced by Japanese partner Shionogi.

Shares in the company leapt 43% to $6.02 in early trade, an 18-month high. The excitement is not only down to the pandemic potential, but also because of the drug’s rocky clinical progress so far. With cases of swine flu on the rise, only two approved antivirals on the market and very little in the R&D cupboard other than peramivir, this first confirmatory pivotal data is great news on many levels (Flu antivirals in demand but few options in pipeline, January 12, 2009).

An intramuscular version of peramivir was scrapped only two months ago after BioCryst consistently failed to generate positive phase II data. Further work will focus on the intravenous formulation, which Shionogi licensed a couple of years ago for the Japanese and Taiwanese markets. As such, this positive data generated by the Japanese group gives hope that peramivir does actually work.

BioCryst has been remarkably unsuccessful in running positive trials, none of its phase II studies in either formulations met primary endpoints, although signs of anti-viral activity were evident. Shionogi meanwhile has managed to generate positive phase II and now phase III data, using the intravenous formulation. Although this evidence probably cannot be used for any US filing, it is certainly encouraging progress.

Strategic stockpiles

Despite the lack of clinical progress in the US, BioCryst is trying hard to get the drug involved with strategic stockpiling efforts. It has submitted IV peramivir for pre-emergency use authorisation (EUA) review, which grants one-year approval without need for further development, although the FDA can rescind this authorisation at any time.

The company is also preparing an inventory sufficient to treat 1,000 patients for the US Centers for Disease Control and Prevention strategic stockpile, although the government has not actually asked for delivery yet or settled on a price. Whether this happens is determined by the EUA.

The company is already discussing phase III trials with the FDA. This will be in a hospital setting and is likely to include a comparator arm. Although BioCryst has not managed to establish non-inferiority over Tamiflu, Shionogi has at least managed this. The largest of the phase III studies reported today was conducted during the 2008-2009 flu season, using two different doses of IV peramivir given once-daily against oral Tamiflu twice daily. It enrolled 1,099 patients, in Japan, Korea and Taiwan, and both doses of peramivir demonstrated non-inferiority.

If BioCryst can replicate these results, it would stand a good chance of winning approval in the end. Further cash will be required to get there, but this is likely to come from the US government.

At the beginning of 2007, the US Department of Health and Human Services (DHHS) awarded BioCryst $103m under a four year contract to develop peramivir. BioCryst ended the first quarter with $54m, enough to last out to 2010, but probably not enough to complete the drug's development. The outcome of talks with both the FDA and HHS are keenly awaited.

Important differentiation

Like Roche’s Tamiflu and GlaxoSmithKline’s Relenza, peramivir is a neuraminidase inhibitor. It is differentiated on administration, the other drugs are an oral pill and an inhaled drug, respectively. Although this would appear to be less convenient, BioCryst’s angle is that the drug could be useful in an elderly or very sick population, who might struggle to swallow or inhale the other drugs.

In normal conditions this argument might seem weak, but in the midst of a flu pandemic it will fall on receptive ears in governments around the world keen to stockpile medicines to protect their populations.

Cases of swine flu continue to rise in many countries including the UK, surprising many experts who had expected prevalence to drop off over the summer. If the virus does become more dangerous and more severe cases start occurring, an intravenous antiviral could certainly see high demand.

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