GlaxoSmithKline and Amicus Therapeutics have suffered a setback on the news that their Fabry disease drug migalastat has failed in a late-stage study.

The partners have announced six-month results from the first Phase III study of migalastat monotherapy in people with Fabry disease. In the 67-patient study, 13 out of 32 people (41%) in the migalastat treatment group demonstrated a 50% or greater reduction in kidney interstitial capillary GL-3 (ie fat deposits) versus 9/32 (28%) for those on placebo.

Amicus said that this difference "did not achieve statistical significance.   according to the pre-specified primary endpoint analysis". However, a secondary analysis, assessing the percentage change in kidney interstitial capillary GL-3 from baseline to month six, showed a median reduction of 41% in the migalastat group versus 6% for placebo. To date, no drug-related serious adverse events have been observed.

John Crowley, Amicus chief executive, noted that the firms anticipate twelve-month results from this study in the first half of 2013. "Once we have [that] data, we intend to meet with the Food and Drug Administration to discuss a US approval pathway," he added, saying "we continue to believe that migalastat may become an important treatment option as an oral monotherapy drug for men and women with Fabry disease who have amenable mutations".

Marc Dunoyer, head of GSK rare diseases, noted that "while these six-month data are encouraging, there is additional work to be done". He added that in addition, a second Phase III Fabry monotherapy study "will add to the totality of our data and give us a more complete picture of the clinical effect of migalastat".

That 18-month study is comparing migalastat to standard-of-care infused therapy using enzyme replacement therapies for Fabry's, namely Sanofi's Fabrazyme (agalsidase beta) and Shire's Replagal (agalsidase alfa). The 60-patient trial is fully recruited and due to report in 2014.

Amicus investors fear the worst for migalastat and its shares sank over 50%.

GSK pays $150 million to settle generic Flonase case

Meantime, GSK has reached a $150 million preliminary settlement with US wholesalers who claimed the company improperly delayed generic entry to the market of its nasal anti-allergy spray Flonase (fluticasone).

The Daily Telegraph reports that the settlement was reached with, among others, AmerisourceBergen, Cardinal Health and McKesson, who maintained that GSK had abused the Citizen's Petition process to maintain a monopoly. The preliminary settlement was approved by the US District Court for the Eastern District of Pennsylvania.

The newspaper quotes a GSK spokesman as saying that the firm "has reached an amicable resolution with the plaintiffs to bring these matters to a close". The firm adds that the parties agree the settlement "is not an admission or evidence of any violation of any statute or law, or of any liability or wrongdoing by GSK".

The spokesman concluded by saying that "we have entered the settlement to remove the protracted disruption, expense and uncertainty of continuing litigation".