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