A Pennsylvania state court judge has declared a mistrial in a case involving

Wyeth

(WYE)

, overturning last week's jury verdict that the company's drug Prempro caused a woman's breast cancer.

Wyeth asked for the mistrial after a jury said on Oct. 4 that the company should pay the woman

$1.5 million in compensatory damages. The jury had been scheduled to consider punitive damages when the mistrial was declared by Judge Norman Ackerman of the Philadelphia Court of Common Pleas.

Wyeth is facing

about 5,000 personal injury suits alleging that the hormone replacement drugs Prempro and Premarin raised the risk of breast cancer, ovarian cancer, stroke or heart attack.

The Pennsylvania case was the second to go to trial. Wyeth won the first trial last month in a federal court in Arkansas.

Wyeth said its request for a mistrial wasn't opposed by the Pennsylvania plaintiff, but the company didn't say why it had sought a mistrial or whether the judge explained his reason for granting the request.

By midafternoon Wednesday, Wyeth's stock was off 21 cents, or 0.4%, at $51.44.