Metastatic breast cancer, also known as stage 4 breast cancer, is cancer that originally began in the breast before progressing to other parts of the body; nearly 30% of women diagnosed with early-stage breast cancer will see their disease metastasize and spread to other organs like the liver and, in some cases, the brain, according to the Breast Cancer Research Foundation.
Any tumor biology of breast cancer can produce metastatic disease, but the more aggressive types—or “triple negative” breast cancer, meaning breast cancer that lacks estrogen—tend to produce more metastatic disease than other tumor types.
While there is currently no cure for metastatic breast cancer, there are treatments, and recent advances in research can offer hope and even prolong life for those living with the cancer.
Research presented last month at the European Society for Medical Oncology Congress (ESMO) 2024 provided a deeper look into what these advances are and just how soon patients could begin using new therapeutics.
Here’s a deeper look into four promising treatment options.
T-DXd proves active against HER2-positive, advanced metastatic breast cancer with or without brain metastases
About half of patients with HER2-positive metastatic brain cancer go on to develop brain metastases. HER2-positive breast cancer is a breast cancer that tests positive for a protein called human epidermal growth factor receptor 2 (HER2). This protein promotes the growth of cancer cells.
In August 2022, the FDA approved trastuzumab deruxtecan (T-DXd), a drug used to treat various types of cancer that overexpress the HER2 protein.
The drug works by delivering a chemotherapy drug directly to cancer cells in hopes of stopping them from spreading and ultimately killing the cancer cells. Up until this point, the drug was primarily being used for treatment of breast cancer, stomach cancer, advanced lung cancer and advanced colorectal cancer.
But a recent study from researchers in Germany found that using the drug to help treat women with HER2-positive metastatic breast cancer, irrespective of the presence of brain metastase, showed substantial and promising results—so much so, doctors can now prescribe this to their patients.
“While many oncologists may have already been using T-DXd to treat their patients with brain metastases based on retrospective data, it is wonderful to see confirmatory phase 3 clinical trial data supporting this practice,” Dr. Jenna V. Canzoniero, of the Johns Hopkins Sidney Kimmel Cancer Center in Baltimore, said at ESMO 2024.
Research suggest majority of metastatic breast cancer express some degree of HER2 and may be considered for treatment
For metastatic breast cancer patients who have never received chemotherapy, the use of T-DXd was found to be a safe introduction therapy for treatment, according to data from a new trial. Prior results from this trial showed that T-DXd significantly improved outcomes when compared to physician’s choice of chemotherapy.
Researchers measure this in what they call PFS or progression-free survival.
It’s a measurement of how long a patient with cancer lives without the disease getting worse, during and after treatment. It’s a common endpoint in clinical trials for cancer drugs and is used to evaluate how well a new treatment works.
In this case, the trial results suggested that the wide majority of metastatic breast cancer patients tested expressed some degree of HER2 and may be considered for treatment with T-DXd.
Research finds chemo-free regimen for HR+/HER2+ disease may be effective treatment option
While chemotherapy is a common treatment for breast cancer patients, new research found that a chemotherapy-free regimen combining dual HER2-targeted therapy including endocrine therapy, particularly with the addition of KISQALI® (ribociclib), may be an effective treatment option for patients with HER2+ and HR+ metastatic breast cancer.
Ribociclib is a daily oral tablet (or two) that is a targeted therapy called a CDK4/6 inhibitor that shuts down certain processes that cancer cells need to divide.
“This study, along with the PATRICIA subgroup analysis reported at ASCO 2024, support a paradigm shift toward considering endocrine-based, rather than chemotherapy-based, treatment regimens for ER/PR-positive, HER2-positive breast cancer,” Canzoniero said ESMO 2024.
Paclitaxel plus atezolizumab shows promise in metastatic TNBC
For breast cancer patients who cannot undergo surgery to remove the tumor or the breast, medications like chemotherapy or oral tablets are commonly prescribed as the first line of treatment. But to better understand what combination of specific medications and/or chemotherapy work best depending on the specific type of breast cancer, researchers led a trial to learn more.
What they found was the combination of atezolizumab and paclitaxel resulted in significantly longer progression-free survival than the combination of atezolizumab and carboplatin–cyclophosphamide.
So, what does that mean?
Atezolizumab, an injection, and paclitaxel, a form of chemotherapy, when used together was found to work best at treating most forms of breast cancer, when compared to using atezolizumab and another injection.
Most importantly, researchers found that the combination “showed promise in improving survival outcomes for patients with TNBC.” TNBC is triple negative breast cancer, one of the most difficult breast cancers to treat because it’s aggressive and resistant to hormonal therapy and HER2-targeted treatments.