Tests for HER2 therapies not so good

 

As Yogi Berra prophetically declared, “Prediction is hard, particularly about the future.”

Just because a theory sounds great does not mean that it will actually work so well.  Maybe, eventually targeted therapy will become very effective but for now it should be advertised as it really is.

from the New York Times

Dr. Linda Griffith was at a conference in Singapore in early January when she felt a lump in her breast. She assumed it was nothing — a cyst. And anyway, she had no time for it. She was returning on a Sunday night and the next Tuesday morning was leaving for a conference in Florida.

But she had a mammogramultrasound and biopsy within hours of getting off the plane. The news was not good: she had cancer.

Then the complications began. Dr. Griffith, director of the Center for Gynepathology Research at M.I.T., had a test to see whether her tumor had extra copies of a protein, HER2. If it did, it would respond to a drug, Herceptin, which blocks the protein and stymies the tumor’s growth.

Drugs aimed at disabling proteins that spur cancer are, many oncologists say, the future of cancer therapies. Only a few are available now but almost every new drug under study is designed to disable cancer-fueling proteins.

But these so-called targeted therapies are only as good as tests to find their protein targets. And while most patients do not yet know it, those tests can be surprisingly unreliable.

Acknowledging the problem, cancer specialists on Monday announced new testing guidelines for one protein target, but as new targets are identified, the problem continues to grow.

The test on Dr. Griffith’s tumor was negative. Or was it? One small area of her tumor stained chocolate brown, indicating lots of HER2. The rest was a cream color, indicating no extra HER2 protein.

Yet her treatment hinged on this result. A HER2 positive tumor has a bad prognosis. Herceptin can make that prognosis good, reducing the chances that the cancer will come back by 50 percent and reducing a woman’s risk of dying by 40 percent.

But Herceptin, costing $42,000 a year wholesale, causes flulike symptoms and also has a rare, serious side effect, severe heart damage that can even be fatal.

 

Cancer Fight – Unclear Tests for New Drug – NYTimes.com.

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