The "positive" step follows last month's announcement by the UK company that the New Drug Application (NDA) for Flutiform (fluticasone/formoterol) would be delayed in the US after the FDA "unexpectedly" queried one particular undisclosed design aspect of the clinical trial programme.
The FDA has since confirmed SkyePharma will need to undergo an additional clinical study and provide additional efficacy data.
The FDA and SkyePharma have agreed on an approach for this additional clinical work but details will not be officially finalised until the end of October.
"We're viewing it as positive. We have a defined way forward. It's not too onerous," SkyePharma chief operating officer Dr Ken Cunningham told in-PharmaTechnologist.com.
While the majority of the FDA request remained undisclosed, Cunningham said the company would embark on a 12-week, SE1-based study, which is a new indication or a significant modification of an existing indication, including removal of a major limitation to use, such as second line status. The number of patients would be around the 300 mark, he said.
"This is additional data. It is not based on the results [to date], but looking at the programme, [the FDA] was wanting to look at it from this angle as well. This is not based on concerns of the existing data," Cunningham said.
The company would also have to submit additional Chemistry, Manufacturing and Controls (CMC) data to support the study, he said.
The requirement for new data will set the NDA submission back to the second half of 2008.
SkyePharma was to submit the NDA in the first quarter of next year.
The company anticipates the cost of the additional work to be in the order of £3m (€4.4m) to £5m (€7.4m).
The additional US workload would not affect the Europe submission of Flutiform, which is expected to be at the end of next year, Cunningham said.
Flutiform is a fixed dose combination of a long-acting bronchodilator (formoterol) with the inhaled steroid fluticasone, supplied in the company's proprietary non-CFC metered dose aerosol inhaler equipped with a dose counter.
In May 2006, SkyePharma licensed Flutiform to Kos Pharmaceuticals to market in the US, with an option on the Canadian market. However, six months later US pharma Abbott Laboratories announced its intentions to acquire Kos for $3.7bn, and became the new marketing partner for SkyePharma's Flutiform.
Despite estimated development costs approaching $60m, the company have high hopes for the product as it is poised to enter a large market with relatively limited competition. The only two approved combination drugs are GlaxoSmithKline's Advair/Seretide (salmeterol and fluticasone) and AstraZeneca's Symbicort (budesonide and formoterol), both of which are blockbusters.
The US market for asthma drugs exceeded $10bn (€7.8bn) in 2005 and the fastest-growing segment of this market is fixed combination treatments.
SkyePharma believed Flutiform had the potential to be a $1bn-a-year blockbuster.