Genentech Says Its Breast Cancer Drug Can Increase Risk of Heart Problems

The FDA and Genentech, Inc. have warned healthcare professionals by means of an August 2005 "Dear Doctor" letter of study data linking Herceptin (trastuzumab) therapy to a significantly increased risk of cardiotoxicity.  This news was broadcast by an alert sent on August 31, 2005 from MedWatch, the FDA’s safety information and adverse event reporting system.

Herceptin is indicated for use alone in chemotherapy-experienced patients, and with paclitaxel in chemotherapy-naive patients, for the treatment of HER-2–positive metastatic breast cancer.

According to the Dear Doctor letter from Genentech, a preliminary analysis of the recent study data suggests that Herceptin can significantly increase the risk of heart problems.  The increase is "significant" compared with patients who received only chemotherapy.

In more detail, the study of 2,043 breast cancer patients found a higher incidence of damage to the heart in the 1,019 patients taking Herceptin. Such damage can lead to heart failure and, in some cases, death.  The August 2005 Dear Doctor letter from Genentech says:

A statistically significant increase in the 3-year cumulative incidence of . . . congestive heart failure and cardiac death was observed in patients who received the Herceptin-containing regimen, [amounting to 4.1 percent, compared with chemotherapy alone, which was put at 0.8 percent].

The Dear Doctor letter says that Herceptin’s label already includes information about possible heart failure and heart ventricle problems. This recent study was intended to quantify the risk, according to the Genentech letter.

Genentech stated in their August 2005 letter to doctors and other healthcare professionals that their analysis of the study results, which were first presented at a conference in May 2005, is ongoing.

(Posted by: Tom Lamb)