ASCO herceptin trial updates for primary BC

[Hopeful]

Thanks for posting, Christine. I am a little confused about the ending of the article, which reads:

"Interestingly, Perez also found that estrogen-receptor-positive tumors experienced a 15 percent improvement, even though many physicians had believed these tumors did not respond well to Herceptin.

'That's going to be news to a lot of people,' Perez said."

I wasn't aware that there was a question about the efficacy of Herceptin in Her2+/ER+ patients, and don't know what the "15% improvement" refers to.
Does anyone know?

Hopeful

[RobinP]

People that are her2 positive and hormonal positive have a lower rate of relapse in the first few years after diagnosis than her2+ that are hormonal negative. Therefore, the benefit for the hormonal positives may be less as their risk of relapse is less, perhaps somewhere around 15%, if the article quote is correct.

[Hopeful]

Robin,

I have not seen anywhere that the relative benefits of Herceptin were 52% for hormone neg, and only 15% for hormone pos. All the quotes state a relative 50% benefit across the board. That is why the 15% does not make sense to me. Could it be 15% absolute benefit? That seems to correlate better with the math (i.e., 85% vs 70%).

Hopeful

[RobinP]

I'm trying to present this lower response in the best light possible. Yes, according to the article link in this post, hormonal positives that were her2+ repsonded less to Herceptin than hormona negatives, probably due to the cancer having another pathway via the hormones to proliferate. I do think the 15% figure that the article gave was less than I would have suspected. Therefore, I would want to check this number before I bought into it. Also, remember that maybe hormonal positives repsond less to H. but hormonal positives do relapse less than hormonal negatives .

[Lani]

Herceptin both presented at evening symposia at San Antonio 2006 that the improvement in recurrence rates for her2+ bc by the addition of herceptin to chemotherapy were the same, whether the her2+ bc was ER+ or ER- according to the data as evaluated to that date.

I read the last sentence as saying there was some benefit found for her2-ER+ bc--which might be because some of these metastasize after becoming antihormonal resistant as her2+ bc. Perhaps the herceptin prevented that or treated that.

Am just speculating...this was my take on it...

[Lani]

ie, that the her2 testing was inaccurate, thus some her2-ER+ patients were found to benefit from herceptin...it seems her2 testing is plagued by both false negatives and false positives:


But one of the slides Perez screened at the annual meeting of the American Society of Clinical Oncology showed that some patients who were classified as HER2-negative got the same benefit as those who tested positive. Perez's data contained too few patients to be statistically significant, but another researcher was scheduled to present similar findings Tuesday in a bigger set of patients.

That caused a buzz among the cancer doctors gathered at McCormick Place, many of whom said the finding raised serious questions about their ability to offer patients the best possible treatment.

Dr. Kathy Albain, director of breast research at Loyola University Health System in Maywood, predicted the data would cause "mass confusion," adding, "It will give me pause to remeasure someone who is initially HER2-negative."

Perez also suggested it might make sense to retest anyone whose first test was negative, just in case it's a false result. "I'm worried about excluding patients who might benefit," she said.

Drug expensive, risky

But Dr. Dennis Slamon of UCLA, who is largely credited with developing Herceptin, noted that false-positive results are also problematic, because the drug costs about $3,000 a month and has sometimes-serious side-effects, including a heightened risk of heart failure.

Dr. Michael Press, a pathologist at the University of Southern California, said as many as one-third of positive antibody tests "could be false-positives."

Slamon called for a high-level task force to figure out how to reduce errors in testing for HER2. As a first step, he said, any negative tumor samples of women who got Herceptin in the clinical trials should be retested by independent, "blinded" pathologists to make sure they're true negatives.

Slamon said there have always been "technical challenges" to determining whether a patient is positive or negative for HER2. One study found that when five pathologists looked at the same slides, they disagreed on the diagnosis in half the cases. "This will bring it to a head," he said, "and that's a good thing."

Early errors found

Shortly after Herceptin was approved by the FDA in 1998, studies began showing that the lab tests to determine if breast-cancer patients should get the drug often yielded false results.

At first it was believed most of the bad results occurred when less-experienced, community laboratories processed the samples or used non-standard test kits. So researchers insisted the tests be performed in a central lab that has processed at least 100 HER2 tests a month for six months.

But Perez said Monday that some of the women who responded to Herceptin in her trial had received negative test results from the central pathology lab that was entrusted with overseeing all the samples.


http://m.trb.com/b/ss/tribglobal/1/...&hp=N&[AQE]