Drug Combo Improved Survival For Women With Triple-Negative Breast Cancer

Woman in hospital gown undergoes a mammogram.
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  • A new study finds that a drug combination may help treat triple-negative breast cancer.
  • This type of cancer can be very difficult to treat with traditional treatments.
  • The study found a monoclonal antibody medication in combination with chemotherapy may help improve survival rates for people with this type of cancer.

Researchers may have identified a new effective treatment regimen for patients with metastatic triple-negative breast cancer (TNBC). 

A new clinical trial found that atezolizumab, a monoclonal antibody medication, combined with carboplatin, a chemotherapy drug, may significantly improve survival in people with TNBC. 

Atezolizumab is an anti-programmed death-ligand 1 (PD-L1) monoclonal antibody medication that stimulates the immune system to attack cancer cells.

While past clinical trials have shown that atezolizumab combined with certain chemotherapy drugs did not improve survival outcomes in people with metastatic TNBC, that was not the case in the most recent study.

Experts say there’s a need to identify new treatment options since some people with TNBC don’t respond well to available treatments.

“The combination of atezolizumab with carboplatin shows a significant improvement in both progression-free survival and overall survival in metastatic TNBC patients, regardless of PD-L1 status. This suggests a potential shift in the therapeutic approach for this patient group,” said Dr. Wael Harb, a board-certified hematologist and medical oncologist at MemorialCare Cancer Institute at Orange Coast and Saddleback Medical Centers in Orange County, CA.

The findings were published in JAMA Oncology Thursday.

Better treatment for triple-negative breast cancer

The researchers recruited 106 people with metastatic TNBC. 

The participants were randomized to receive either intravenous carboplatin alone or intravenous carboplatin with atezolizumab (1200) mg every three weeks. 

The trial was conducted at six medical centers between August 2017 and June 2021.

The team found that the combination of carboplatin and atezolizumab improved progress-free survival, or the amount of time before the cancer progresses, from a median of 2.2 to 4.1 months. 

The combination treatment increased overall survival from a median of 8.6 months to 12.6 months.

“The combination of immunotherapy (atezolizumab) and carboplatin improved the amount of time before disease progressed as well as patient’s overall survival when compared to carboplatin alone,” said Dr. Brittney Zimmerman, a breast medical oncologist at Northwell Health Cancer Institute in Huntington and Riverhead, NY.

Those with high tumor-infiltrating lymphocytes, a high mutation burden, obesity, and uncontrolled blood glucose levels experienced the greatest benefits.

“The study’s findings could modify the current treatment paradigm, offering a new effective combination for a broader range of patients, irrespective of PD-L1 status,” says Harb.

How drug combo is key for cancer treatment

Typically, patients with TNBC are treated with chemotherapy and in some cases, immunotherapy as well. 

Some patients, however, don’t respond to immunotherapy. 

This may be due to various factors, including low mutation burden or lack of PD-L1 expression, according to Harb. 

“However, in this trial, the improvement in outcomes was not related to PD-L1 status. Patients with a high number of mutations within their tumor had improved outcomes in this study,” says Zimmerman. 

Recent data has suggested that immunotherapy when combined with chemotherapy, can improve outcomes, says Zimmerman. 

But in recent trials, combining atezolizumab with other chemotherapy drugs didn’t boost survival. However, a different type of chemotherapy drug may help explain why survival was extended in this trial.

Atezolizumab improves the immune system’s ability to fight cancer cells, explains Harb, while carboplatin, a chemotherapy drug, damages the DNA of cancer cells. 

“However, carboplatin works by a different mechanism, which might enhance the activity of immunotherapy such as atezolizumab,” Harb said. “Their combined use likely offers a synergistic effect, boosting the overall efficacy of the treatment.”

Future studies will need to explore the benefits of combining atezolizumab with carboplatin and identify which patients will experience the greatest benefits.

“Immunotherapy is an exciting class of medications in the field of medical oncology,” says Zimmerman. 

The bottom line:

Researchers may have identified a new effective treatment regimen for patients with metastatic triple-negative breast cancer (TNBC). A clinical trial found that atezolizumab, a monoclonal antibody medication, combined with carboplatin, a chemotherapy drug, may significantly improve survival. 

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