AstraZeneca drug extends prostate cancer survival
By Michael Kahn and Ben Hirschler
BARCELONA/LONDON, Sept 25 (Reuters) - Patients with advanced prostate cancer given AstraZeneca's (AZN.L) experimental pill ZD4054 live around seven months longer than those on placebo, according to results of a clinical trial presented on Tuesday.
But the drug failed to show an improvement in progression-free survival, a measure of how long patients survive before their condition worsens.
AstraZeneca said in July that ZD4054 demonstrated overall survival benefits and was being moved into final Phase III studies. The scale of the improvement was revealed at the European Cancer Conference in Barcelona.
The Anglo-Swedish firm hopes the new medicine, which could be filed for approval in 2009, will revive its fortunes in the fast-growing cancer treatment market.
Men with advanced prostate cancer are normally given hormonal therapies, which can be highly effective. But in most cases resistance develops -- leaving Sanofi-Aventis's (SASY.PA) chemotherapy drug Taxotere, which improves survival by around 2.4 months, as the only option.
Nick James, professor of clinical oncology at the Institute for Cancer Studies in Birmingham, England, said the Phase II trial results with the new once-daily pill were "promising".
In the study of 312 pain-free or mildly symptomatic patients with metastatic hormone-resistant prostate cancer (HRPC), the median survival time for those on 10 milligrams of ZD4054 was 24.5 months, against 17.3 months for placebo.
Those given a 15 mg dose of the drug lived 23.5 months.
However, the study failed to show a statistically significant difference in progression-free survival (PFS), which had been its primary endpoint.
"It is usual to use PFS as an endpoint in Phase II studies, however it can be difficult to measure accurately in patients with metastatic HRPC. Overall survival is an unambiguous endpoint and clearly an important outcome for patients," James said.
Industry analysts said ZD4054 could be a blockbuster, with potential annual sales above $1 billion, if it proved successful in final Phase III and regulators were convinced of its benefits.
The field is littered with prostate cancer drugs that have not won approval, including a similar product called Xinlay from Abbott Laboratories (ABT.N), which was rejected by U.S. regulators in 2005 after it failed to delay disease progression.
ZD4054 works by blocking the action of a cell protein called endothelin A, which is believed to play a key role in prostate tumour growth.
