Comparative Arimidex Data From ASCO

Results of a comparative study of Zeneca's third-generation aromatase inhibitor Arimidex (ZD 1033) and megestrol acetate suggest that the two drugs are equally effective, but that megestrol was not as well tolerated. The study was presented at the American Society of Clinical Oncology held in Los Angeles, USA, last week.

The trial involved 378 patients with advanced breast cancer who had failed prior antiestrogen treatment, and were randomly assigned to one of two doses of Arimidex (1mg or 10mg by mouth once daily) or Megestrol at a dose of 40mg four times daily. There were no statistically significant differences between the two drugs in all of the efficacy endpoints, including time to progression, time to treatment failure, and survival. However, more patients had weight gain and thromboembolic disease reported as adverse events on megestrol.

The regulatory package for Arimidex is currently being reviewed by the UK Medicines Control Agency, following its submission in March. Submissions for major European markets and the USA are expected to be completed by the end of the second quarter of this year, said Zeneca.