Study: Immunotherapy shows promise in triple-negative breast cancer

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THIS INFORMATION HAS BEEN UPDATED on 04/06/19: Based on published research studies, the FDA approved atezolizumab (Tecentriq) used in combination with the chemotherapy drug nab–paclitaxel (Abraxane) for women with locally advanced or metastatic triple-negative breast cancer that cannot be treated surgically and whose tumors are positive for a protein called PD-L1. The FDA also approved a companion diagnostic test called the VENTANA PD-L1 Assay, to identify patients with triple-negative breast cancer who are candidates for this treatment.

Patients diagnosed with triple-negative breast cancer (TNBC) do not have many treatment options. Immunotherapy, a new type of cancer treatment, pushes the body’s natural defense or immune system to fight cancer. A new immunotherapy drug, atezolizumab (Tecentriq) may improve survival for patients with metastatic TNBC. (07/11/17)  


This study is about:

Atezolizumab (Tecentriq) is a type of cancer treatment known as immunotherapy. These drugs help the body's immune system detect and attack cancer cells. Compared to other types of breast cancers, TNBC appears more sensitive to drugs such as atezolizumab. In this study, researchers used it to treat patients with metastatic TNBC. There were two distinct groups looked at in the study: 

  • patients who received atezolizumab as a "first-line treatment" (meaning they had not received any previous treatment for their metastatic breast cancer)
  • patients who received atezolizumab as a "second-line" or later treatment (meaning they received atezolizumab after their cancer recurred or progressed after one or more previous treatments for their metastatic disease)

Why is this study important?

TNBC generally affects a younger population, is more aggressive and thus has a poor prognosis.  Patients with TNBC have few treatment options. This study offers hope that targeted immunotherapies like atezolizumab will improve survival for women with TNBC.

Study findings: 

The researchers found that patients who responded to atezolizumab survived longer than those who did not respond. Additionally, more patients who received the drug as a first-line treatment responded than those receiving it as a second or third treatment.

  • 10% of patients (15 of 112) responded to atezolizumab.
  • All patients who responded to the drug were still alive at 2 years.
  • Non-responders survived about 9 months.
  • 26% of patients receiving atezolizumab as their first treatment had an overall response compared to 11% of those receiving it as a second or third treatment had a similar response.

The researchers compared the tumors of patients who responded to treatment and those who did not, to try to find "markers" that could predict response to atezolizumab. Tumors with greater amounts of a protein called “programmed cell death ligand 1 (PD-L1)” or greater amounts of lymphocytes (a type of white blood cell) responded better than tumors that lacked these markers.

What does this mean for me?

If you are diagnosed with advanced triple-negative breast cancer and analysis shows that your tumor has certain markers, atezolizumab or a drug like it could be an option for your treatment. This and other similar immunotherapy drugs are being studied in clinical trials for TNBC, as well as for patients with BRCA mutations. Atezolizumab is not yet FDA approved for TNBC although it has been approved for other cancers. Immunotherapy agents are also being studied in combination with other drugs to see if they can increase the number of TNBC patients who respond to this type of therapy. 

Questions to ask your health care provider:

  • Might I benefit from participation in clinical trials using drugs like atezolizumab?
  • Are there other investigational medications that might benefit me?


Study background:

The immune system can tell the difference between normal and abnormal cells in the body. When functioning properly, the immune system can find and destroy abnormal cells such as cancer while leaving normal cells alone. Some cancers learn how to escape the immune system by producing a protein called PD-L1 (Programmed Death Ligand 1) that can trick immune system into thinking the cancer cells are normal, causing the immune system to leave the cancer cells alone.

Atezolizumab is an antibody that stops the protein PD-L1 from binding to the immune cells. By blocking these interactions, atezolizumab restores the body’s natural immune response to a tumor. This drug has received accelerated FDA approval for patients with advanced or metastatic bladder cancer who cannot receive standard chemotherapy. Atezolizumab is also approved for treatment of non-small cell lung cancer in cases where the disease has progressed during or after chemotherapy. 

Because TNBC has more PD-L1 protein than other types of breast cancers, researchers theorize that immunotherapies like atezolizumab may be used to treat some patients with TNBC

Researchers of this study wanted to know:

Researchers wanted to see if atezolizumab could increase survival for patients with triple-negative breast cancer.

Population(s) looked at in the study:

Peter Schmid, MD, PhD from the Barts Cancer Institute, Queen Mary University in London presented this at the Annual American Association for Cancer Research (AACR) Meeting April 1-5th.

This study initially included only patients with TNBC and PD-L1 protein on 5% or more of their tumor cells. It was later opened to all patients with TNBC regardless of PD-L1 protein amounts. Patients received atezoluzimab every 3 weeks for 1 year. Patients were offered the option to continue treatment until they no longer benefited from the drug. 

Study findings: 

  1. 19 patients received atezolizumab as first-line treatment, while 93 had received at least two lines of prior therapy.  For these 112 patients the response rate was
    • 26% for patients receiving atezolizumab as their first-line treatment.
    • 11% for those receiving it as a second or third-line treatment.
    • 17% in patients whose PD-L1 levels were at or above 5%, and 8% in individuals with PD-L1 levels below 5%.
  2. For responders both one- and two-year survival rates was 100%.
  3. For non-responders one- and two-year survival rates were 33% and 11% respectively.
  4. For patients who received atezolizumab as a first-line treatment one- and two-year survival rates were 63% and 47% respectively.
  5. For patients who were previously treated overall one- and two-year survival rates were 37% and 18% respectively.
  6. One-year overall survival for patients with high PD-L1 was 45% versus 37% for those with low or no PD-L1.


This was an early (phase 1) study. This means all patients received the study agent, so no "control group" (a group that represents the standard of care treatment) was used for comparison. The authors explained that the survival comparisons were based only on past control groups rather than a head-to-head comparison. Additionally, the study was funded by the drug manufacturer, which is common for studies looking at new therapies.


In this study, patients with metastatic triple-negative breast cancer who responded to atezolizumab as treatment lived significantly longer than those who did not show response to the medication. The drug is not yet approved for use in breast cancer outside of a clinical trial. Current trials are evaluating the drug compared to standard of care for patients with metastatic TNBC.

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Posted 07/11/17


American Association for Cancer Research 2017 Annual Meeting Proceedings 

AACR Press Release: Triple-negative Breast Cancer Patients Who Responded to Immunotherapy Had Long-term Survival Benefit


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