U.S.

Risks Cited On Cancer Drug

By CBSNews.com staff CBSNews.com staff

May 5, 2000 / 8:55 AM EDT / CBS

When Herceptin hit the market in 1998, it was hailed as a breakthrough drug for advanced breast cancer patients. In combination with chemotherapy, it has successfully prolonged thousands of lives like Amy Applebaum's.

"As far as I'm concerned, Herceptin is a miracle drug," Applebaum said.

But drug benefits always come with risks, and Friday there is a new warning from the makers of Herceptin. Pharmaceutical maker Genentech Inc. has warned doctors that Herceptin is linked to 15 deaths and 47 other adverse reactions in patients.

In a letter to doctors, the company said the adverse effects included allergic shock and extreme respiratory distress, reports CBS News Medical Correspondent Elizabeth Kaledin.

"We sent the letter to oncologists to heighten their awareness and educate them about infrequent adverse events that can occur in certain patients," Genentech spokesman Neil Cohen said.

An estimated 23,000 patients have been treated with Herceptin.

Severe reactions to Herceptin had not occurred in clinical trials before the drug gained Food and Drug Administration approval in 1998, Cohen said.

But sometimes reactions can't be foreseen in trials, he said.

"A lot of times you might see some safety issues once the drug gets put into a larger patient population," Cohen said.

"The incidence of severe side effects is .06 of all patients treated, so it's a very rare event," said Dr. Larry Norton of Memorial Sloane-Kettering Cancer Center.

Cohen said he didn't know when the company first heard of the deaths and reactions, but analysis had confirmed the link to Herceptin.

In nine of the 15 deaths, symptoms arose within 24 hours of the time Herceptin was administered, according to the letter.

Genentech is working with the FDA to have the drug's label amended to reflect the new risks, Cohen said.

Herceptin is used to treat breast cancer patients that have too many copies of the HER2 gene. A healthy version of this gene produces a protein that signals cells to grow and multiply normally. But in women with too much HER2, the breast cells reproduce out of control and spread throughout the body. Herceptin, an antibody, blocks excess HER2, shrinking and eliminating tumors.