A woman who claimed that Wyeth’s hormone replacement therapy product Prempro was the cause of her breast cancer has won $1.5 million in compensatory damages in a case heard in Philadelphia, USA.

A second phase of the trial will now get underway on October 12 and will see if Wyeth is liable and required to pay those damages, according to the company, which maintains that there is no scientific basis to support the jury’s assertion that Prempro (conjugated estrogens and ) caused the plaintiff’s cancer.

If the second phase does find Wyeth liable – perhaps because it failed to give adequate warning of the risks - it could also face punitive damages in addition to the compensatory award. Jennie Nelson, aged 67, took Prempro for six years.

In the first federal Prempro trial, a jury in Little Rock, Arkansas, concluded last month that Wyeth was not negligent and had adequately warned patients and doctors of the cancer risk associated with the drug. Wyeth is facing more than 5,000 lawsuits involving its HRT products.

“Wyeth intends to show that the company acted reasonably by performing and supporting studies that examined the known and potential benefits and risks of hormone therapy and in keeping the US Food and Drug Administration, physicians and patients informed of those risks and benefits,” said Wyeth in a statement.

Analysts have suggested that Wyeth has a strong case in showing that it was not negligent, as it changed the labelling for PremPro very quickly after data emerged on the risk of breast cancer with the drug.

Wyeth's stock plunged by more than a quarter in 2002 after a major US government-led study found Prempro was associated with an increased risk of breast cancer, coronary heart disease and stroke. The study, which was due to run until 2005, was terminated at an average follow up of 5.2 years after investigators observed a 26% increase in breast cancer, a 41% rise in strokes and a 29% increase in heart attacks.

Labelling for the drug, which remains on the market, has been updated to reflect this increased risk. Prempro and other drugs in the Premarin (conjugated oestrogens) family contributed around $525 million revenues to Wyeth in the first half of 2006.