Genetic testing changes breast cancer focus

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Cindy Tomaszewski, 34, of Martinez, receives a Herceptin treatment at Georgia Health Sciences University Cancer Center.  EMILY ROSE BENNETT/STAFF
EMILY ROSE BENNETT/STAFF
Cindy Tomaszewski, 34, of Martinez, receives a Herceptin treatment at Georgia Health Sciences University Cancer Center.

In the near future, Dr. Olivier Rixe said, we might stop talking about breast cancer altogether.

As genetic sequencing of tumors becomes more routine and therapies are targeted at specific molecular traits in the tumor, the location of the primary tumor becomes less important, said Rixe, the director of the experimental therapeutics program at Georgia Health Scien­ces University’s Cancer Center.

“This is a new paradigm,” he said. “You do a better molecular classification, identify the target and then you can really deliver the drug you need to give to your patients based on the classification.”

That is already bearing fruit in an “explosion” of breast cancer drugs that have been recently approved or are in the pipeline, Rixe said. Two in particular approved in the past year, and another that looks promising, give breast cancer patients better options, said Dr. Thomas Samuel, a co-leader of multidisciplinary breast cancer program at the cancer center.

Two appear to target the HER2 marker but one, called everolimus, is aimed at breast cancers without HER2 but that are estrogen-positive and whose disease has spread, Samuel said. Many times those patients are receiving hormonal treatments that the cancer develops resistance against.

Everolimus inhibits a cellular pathway important in estrogen-driven cell proliferation.

“When you add everolimus, it sort of re-creates that hormone sensitivity and allows the patient to have another option before they have to go on to some more toxic chemotherapy,” Samuel said. “The approval of everolimus I think is just a sign that we are now entering sort of a different phase of treatment for metastatic breast cancer treatment.”

The HER2 marker is specifically targeted by a widely used drug called Herceptin or trastuzumab. The two new drugs, the recently approved pertuzumab and T-DM1, which is still in clinical trials, target that marker in different ways. Pertuzumab targets a different portion of HER2 than Her­cep­tin. T-DM1 uses Her­ceptin to target the HER2 marker but includes a toxic agent to deliver an additional blow to the cancer cell.

“You increase the efficacy of that compound,” Samuel said.

That could be important to patients such as Cindy Tomaszewski down the road. The 34-year-old mother of three’s breast cancer had already spread to her liver and bone by the time she was diagnosed. She is keeping it in check with regular doses of Herceptin at GHSU, but the new drugs could give her more or better options.

“That is exciting to me,” she said. “Herceptin isn’t that bad so if there is something better, that would be great.”

Unfortunately, Tomas­zewski said she had been told she will need to get the drug every three weeks indefinitely, which she is not thrilled about.

“But if it keeps the cancer from coming back or growing any larger, then I’m willing to do it,” she said.

Having the other options, with fewer side effect than less-targeted drugs, gives oncologists the chance to just keep the cancer in check, Samuel said.

“I think we may end up with that situation where it is a chronic disease, the same way with HIV or any of the other major illnesses,” he said. “What we’ve done is not so much get rid of it but control it to a point where it doesn’t necessarily affect the patient’s ability to live a normal life.”

GHSU can sequence a tumor in 24 hours for about $1,000, which it is doing with some patients, Rixe said.

“But soon we’ll be able to sequence all comers coming to the front door,” he said. “This will impact research and standard of care immediately.”

While she is excited about the new therapies, that is not where Tomaszewski is placing her faith in her future.

“It is encouraging that they can specifically gear my treatment for the specific type of cancer that I have,” she said. “But, honestly, my hope comes from my faith in the Lord and knowing that my days were numbered before I was born and he knew exactly how my life would go and that he knows the number of hairs on my head and loves me. That’s where my faith comes from.”


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