New Drug Combo Boosts Survival Against Aggressive Form of Breast Cancer

MONDAY, Sept. 20, 2021 (HealthDay News) -- New research offers good news for women with an aggressive HER2-positive breast cancer.

A targeted therapy, trastuzumab deruxtecan (T-DXd), sold as Enhertu, triples the length of time that the cancer remains in check when compared with the current gold standard, trastuzumab emtansine (T-DM1).

These drugs can be used as second-line treatments for HER2-positive breast carcinoma that continues to grow after treatment.

"It really truly blew T-DM1 out of water in terms of progression-free survival," said study co-author Dr. Sara Hurvitz, director of breast cancer clinical research at UCLA's Jonsson Comprehensive Cancer Center.

Hurvitz stated that up to 20% breast cancers are found to be HER2-positive. That means the cells have too many human epidermal Growth Factor receptor 2. This causes the cancers to attack more aggressively.

Currently, the first-line therapy for women with this type of breast cancer is HER2 antibody therapy with pertuzumab/trastuzumab plus chemotherapy. T-DM1 (sold under Kadcyla) is the recommended treatment. It includes trastuzumab plus chemotherapy.

Hurvitz stated that the study could change the paradigm.

T-DXd can be administered intravenously to block the growth of the HER2 proteins. It delivers chemotherapy in high doses directly to overexpressed HER2 cancer cells.

T-DXd manufacturer Daiichi Sankyo Inc. funded this new study.

The study involved 524 breast-cancer patients with HER2-positive status. T-DXd treatment resulted in a 72% increase in progression-free survival compared with TDM1.

T-DXd treatment resulted in 76% of the women not showing signs of disease progression after one year. Only 34% of T-DM1 women did not experience disease progression in one year.

Hurvitz explained that this drug prolongs the progression-free time, or when a patient can switch to another therapy if their existing one is not working. Patients will be happy to hear this.

T-DXd also showed tumor shrinkage in nearly 80% of the women treated, compared to 34% with TDM1. According to the study, 16% of TXDXd treated women had no sign of disease within one year. Hurvitz noted that women who had breast cancer spread to the brain seemed to be particularly well-treated by T-DXd.

These findings were presented at this weekend's annual meeting of European Society for Medical Oncology. Research presented at meetings are usually considered preliminary and not published until it has been peer-reviewed.

One of the main safety concerns with this drug is the risk of interstitial lung disease, a group of lung conditions that causes scarring of lung tissues, Hurvitz said. She said that the risk of interstitial lung diseases was very low and women with mild cases were more likely to develop it in this new study.

The study results and their implications for advanced HER2-positive women are also being welcomed by outside experts.

Dr. Charles Shapiro said that T-DXd "represents a new standard in care, which is used in place TDM-1 in advanced HER2-overexpressing Breast Cancers." Professor of Medicine, Hematology, and Medical Oncology at Mount Sinai School of Medicine and Mount Sinai Tisch Cancer Center medical breast-oncologist in New York City. The world looks brighter for breast cancer patients with high HER2 expression.

Jesus Anampa Mesias is a New York City-based medical oncologist. He said that this study could lead to changes in standard care for metastatic HER2-positive patients. "The results of this study are impressive and unprecedented [and] will definitely change how I care for women with metastatic HER2-positive breast cancer."

More information

Learn more about HER2-positive breast cancer at the American Cancer Society.

SOURCES Sara Hurvitz MD is the director of Breast Cancer Clinical Research Program at Jonsson Comprehensive Cancer Center. UCLA. Charles Shapiro MD is professor of medicine, hematology and medical oncology, Icahn School of Medicine. Jesus Anampa Mesias MD is a medical oncologist at Montefiore Einstein Cancer Center. New York City. The European Society for Medical Oncology Congress will be held Sept. 16-21st 2021.