The news could not come at a worse time for the beleaguered company, which has already weathered storms concerning recent disappointments, with Exanta (ximelagatran) failing to gain US approval and Crestor(rosuvastatin) under renewed criticism over its safety profile.
The decision was made after consultation with the European Medicines Agency (EMEA). Astrazeneca agreed that its Iressa Survival Evaluation in Lung cancer (ISEL) survival results would not support European approval.
While improvements in tumour shrinkage (response rate) and time to treatment failure were observed, the results were not statistically significant in survival benefit. However, the ISEL trial did show that certain subgroups (patients with Oriental origin and patients who never smoked) did see survival benefits with Iressa.
Hopes of submitting a new European Marketing Authorisation Application (MAA) were not completely abandoned as Astrazeneca stated that they were considering a new application in the future, after evaluation of the full ISEL.
Research published in the New England Journal of Medicine found responses to Iressa were restricted to patients with specific somatic 'gain of function' mutations in EGFR. Additional studies targeting Iressa at specific demographic groups could offer AstraZeneca an opportunity to salvage some of this drug's commercial potential.
As well as discussions over Iressa's future with the US Food and Drug Administration (FDA) talks were continuing with the Ministry of Health, Labour and Welfare (MHLW) in Japan and all other Regulatory Authorities concerned over the latest clinical data.
Tarceva (erlotinib) produced by Genentech, OSI and Roche is Iressa's closest competitor and is now in a very dominant market position. Both drugs are small molecule, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors. In a marked contrast to Iressa its latest clinical trials showed an improvement in survival of refractory patients, from 4.7 months to 6.7 months.
AstraZeneca is hoping to limit the impact of these disappointing trial results, with chief executive Tom McKillop commenting that Iressa accounted for less than 5 per cent of company profits. However, Iressa, already launched in Japan and the US, represented one of its top growth drivers, with global sales of $113 million (€85 million) in the third quarter of 2004 alone. According to Datamonitor, global Iressa sales would grow to $916 million by 2010.