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Breast cancer drugs show big promise, experts say

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Breast cancer patient Rachel Midgett of Houston, Texas, adjusts her headband before heading to the start line to run in the half marathon of the Las Vegas Marathon on Dec. 4, 2011. Midgett takes an experimental drug called Afinitor. AP

(CBS/AP) Breast cancer experts are tickled pink by two new medicines that could mark the biggest advances in more than a decade. The drugs significantly delay the time until women with very advanced cases get worse.

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One of the experimental drugs, Genentech's pertuzumab, targets cells that make too much of a protein called HER2 - a problem in about one out of four or five breast cancer cases. A new study of 808 women showed pertuzumab held cancer at bay for a median of 18 months when given with standard treatment - versus 12 months for others given just the usual treatment. The study included women from Europe, North and South America and Asia. Herceptin, a standard treatment for certain types of breast cancer since 1998, attacks the same target but in a different way, and the medicines complement each other.

"You don't see that very often. ... It's a spectacular result," said one study leader, Dr. Sandra Swain, medical director of Washington Hospital Center's cancer institute.

"Pertuzumab is a winner" and should win government approval, said Dr. Eric Winer of the Dana-Farber cancer center.

How do the side effects compare? The most common side effects of pertuzumab were diarrhea, rash and low white blood cell counts, which often occur with cancer treatment. Among the 402 women given pertuzumab in addition to Herceptin and chemotherapy, 69 died - compared with 96 deaths among the 406 women given Herceptin and chemo alone. The dual treatment did not cause more heart problems - an issue with other Herceptin combinations.

"We're really pleased that there were no new safety signals" and that pertuzumab is so promising, said Dr. Sandra Horning, Genentech's global development chief of cancer drugs.

The second drug, everolimus - sold as Afinitor by Novartis AG - was tested in another study of 724 women. The study showed that the drug, used in conjunction with hormone-blocking treatments, kept cancer in check for a median of 7 months in women whose disease was worsening even in the face of treatment. A comparison group that received only hormone-blocking drugs had only a 3-month delay in the progression of the disease.

Afinitor works in a novel way, seems "unusually effective" and sets a new standard of care, said Dr. Peter Ravdin, breast cancer chief at the UT Health Science Center in San Antonio, not affiliated with the study or drugmakers.

The combo of Afinitor and hormone-blocking drugs did lead to more side effects - mouth sores, anemia, shortness of breath, high blood sugar, fatigue and lung inflammation. But "the two together have a much greater effect than you would expect from either alone," said study leader Dr. Gabriel Hortobagyi, breast cancer research chief at the University of Texas MD Anderson Cancer Center in Houston. "They snip two wires that are critical" for growth signals to continue, he said.

Results were released Wednesday at the San Antonio Breast Cancer Symposium and online, published by the New England Journal of Medicine.

"These are powerful advances ... an important step forward," said Dr. Harold Burstein, a breast expert at Dana-Farber Cancer Institute in Boston who had no role in the studies.

Here comes the reality check: the drugs will probably be very expensive - up to $10,000 a month - and have so far not proved to be cures. But, even short of a cure, about 40,000 U.S. women each year have cancer that spreads beyond the breast, and treatment can make a big difference in their lives.

Take Rachel Midgett, for example. The 39-year-old Houston woman has breast cancer that spread to multiple parts of her liver, yet she ran a half-marathon in Las Vegas on Sunday. She has had three scans since starting on Afinitor nine months ago, and "every time, my liver lesions keep shrinking," she said.

"My quality of life has been wonderful. It's amazing. I have my hair. ... If you saw me you wouldn't even know I have cancer."

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