For the first time, a drug that targets a protein that drives breast cancer growth has been shown to work against tumors with very low protein levels.
It’s not a cure. But this latest advance in targeted cancer therapy could open up new treatment options for thousands of advanced breast cancer patients.
Up until now, breast cancer has been categorized as either HER2 positive – the cancer cells have more protein than normal – or HER2 negative. Doctors reporting the progress on Sunday said “HER2-low” will become a new category for treating breast cancer.
About half of late-stage breast cancer patients who were previously classified as HER2-negative may actually be HER2-low and eligible for the drug.
The drug is Enhertu, an antibody-chemotherapy combination given by IV. It finds and blocks the HER2 protein on cancer cells while simultaneously unloading a powerful cancer-killing chemical into those cells. It belongs to a relatively new class of drugs called antibody-drug conjugates.
The drug was already approved for HER2-positive breast cancer, and in April the Food and Drug Administration gave it Breakthrough Designation for this new patient population.
In the new study, the drug increased the time patients lived without the cancer getting worse and improved survival compared to patients receiving standard chemotherapy.
The study compared Enhertu to standard chemotherapy in about 500 patients with HER2-low breast cancer that had spread or could not be treated with surgery. The drug stopped the cancer from progressing for about 10 months, compared with about 5 1/2 months in the group receiving regular treatment. The drug improved survival by about six months (from 17.5 months to 23.9 months).
“It’s a practice-changing study,” said Dr. Sylvia Adams, who directs breast cancer care at NYU Langone Health and enrolled several patients in the study. “It addresses a major unmet need for patients with metastatic breast cancer.”
Now it will be important to define the HER2 gray area to ensure the right patients are getting the treatment and then monitor them closely, experts said.
The drug, which costs about $14,000 a month, can have serious complications. Three patients in the study died from a lung disease, which is a known hazard of the drug. Doctors must ensure patients report breathing problems promptly so the drug can be stopped and patients treated with steroids.
The findings were presented Sunday at the American Society of Clinical Oncology annual meeting in Chicago and published by the New England Journal of Medicine. Funding for the study came from Tokyo-based Daiichi Sankyo and UK-based AstraZeneca, who co-developed the drug.
Patients take the drug until they can no longer tolerate it.
“Many people, including many patients, will never have heard of HER2-low breast cancer before,” said the study’s lead author, Dr. Shanu Modi of Memorial Sloan Kettering Cancer Center in New York.
“Finally, we have a HER2-targeted drug that, for the first time, can target this low level of HER2 expression,” Modi said. “This drug actually helps define HER2-low breast cancer. It makes it a targeted population for the first time.”
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https://www.local10.com/health/2022/06/05/researchers-breast-cancer-drug-could-help-more-patients/ Breast cancer drug could help more patients