US regulators seem to agree that a Phase III clinical trial of Shire's Firazyr show it to be safe and effective in patients with hereditary angioedema (HAE), raising hopes that the drug could make it onto the market after all.

The US Food and Drug Administration originally turned down Firazyr (icatibant) - which Shire acquired through its purchase of Jerini in 2008 - because of variations in clinical data, forcing the drugmaker to undertake an extra Phase III trial to generate more data in support of its effectiveness as a treatment for HAE. 

HAE is a rare genetic disorder characterised by recurring and sudden attacks of swelling in the skin (including hands, feet, face and genitals) or the mucous membranes (gastrointestinal tract, larynx or voicebox), which can be extremely painful and even fatal if the larynx swells up and causes suffocation.

According to previously-reported headline results from the additional Phase III trial, called FAST-3, patients with HAE given Firazyr experienced a significantly faster time to the start of symptom relief versus those taking a placebo.

In fact, the data showed that Firazyr induced a 50% reduction in a composite symptom score assessment in just two hours (median value) compared 19.8 hours for the control group, marking a highly significant difference and showing the drug's potential benefit for patients with the condition.

And now, according to documents posted on the FDA's website, the regulator agrees that the trial's results are indeed generally supportive of the drug's efficacy, which is good news given that an advisory panel is due to meet this Thursday to discuss whether it should be approved in the US or not.

Safety profile

In addition, on the safety side, the FDA's documents note that the most common adverse reactions were local injection site reactions, which occurred in nearly all patients who received Firazyr by subcutaneous injection, although these were mild and generally resolved within a few hours of treatment. 

No other major safety concerns have been identified, it said, but added that "this statement is made with the caveat that the overall safety based on relatively limited, intermittent use of icatibant". 

Firazyr is already marketed in 37 countries around the globe, and Shire will no doubt be keeping its fingers crossed that there is life for the drug in the all-important US market yet.