A drug that targets a protein that causes breast cancer growth was first shown to be effective against tumors with low levels of this protein.
However, it is not a cure. This latest breakthrough in targeted cancer therapy could offer new treatment options to thousands of patients suffering from advanced breast cancer.
Breast cancers were previously classified as either HER2-positive (those cells that have higher levels of protein than normal) or HER2-negative. According to doctors, the breakthrough Sunday will allow “HER2-low” to be a new category that can guide breast cancer treatment.
Half of late-stage breast cancer patients who were previously HER2-negative might actually be HER2-low, and therefore eligible for the drug.
The drug is Enhertu, an antibody-chemotherapy combo given by IV. It blocks the HER2 protein in cancer cells and unloads a powerful, cancer-killing chemical within those cells. It is part of a new class of drugs known as antibody-drug combinations.
The drug had been approved for HER2-positive breast carcinoma, and the Food and Drug Administration gave it breakthrough status in April.
The new study found that the drug extended the life expectancy of patients without causing cancer progression and increased survival rates compared to patients who received standard chemotherapy.
Enhertu was compared to standard chemotherapy in approximately 500 women with HER2-low breast carcinoma that had not spread or could not have surgery. Enhertu stopped the progression of the disease for approximately 10 months, compared to about 5 1/2 months in patients who received regular care. The drug increased survival by six months (from 17.5 to 23.9 months).
“It’s an important study,” stated Dr. Sylvia Adams who directs the NYU Langone Health breast cancer care and enrolled many patients in the research. It addresses a significant unmet need in patients with metastatic breast cancer.
Experts said it is now important to identify the HER2 gray zone to ensure the right patients get the treatment. They also need to be closely monitored, they added.
The drug can cause severe side effects and costs around $14,000 per month. The drug’s known hazards caused three deaths in the study. To ensure that the drug is stopped and patients are treated with steroids, doctors must immediately notify patients of any breathing problems.
These findings were presented Sunday at the American Society of Clinical Oncology’s annual meeting in Chicago. They were also published by New England Journal of Medicine. The study was funded by Tokyo-based Daiichi Sankyo, and U.K.-based AstraZeneca.
Patients are prescribed the drug until they become unable to tolerate it.
“A lot people, including many patients, won’t have heard about HER2-low breast carcinoma before,” Dr. Shanu Modi, of Memorial SloanKettering Cancer Centre in New York, said.
Modi stated that Modi finally found a HER2-targeted medication that could target low levels of HER2 expression. Modi said that the drug helps define HER2-low breast carcinoma. This drug makes it possible to target a specific population for the first-time.
