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  • Writer's pictureSurviving Breast Cancer

Immunotherapy Response Monitoring in Patients with Breast Cancer

What is Immunotherapy?

Immunotherapy is a type of cancer treatment that seeks to harness the power of the body’s immune system to fight cancer. It works by stimulating or “training” the body’s own natural defense system to recognize and attack cancer cells, essentially giving it the ability to seek out and eliminate tumor cells on its own. Immunotherapy has recently been used in the treatment of metastatic breast cancer (MBC). Examples of breast cancer immunotherapy include monoclonal antibodies, checkpoint inhibitors, cytokine therapy, and adoptive cell therapies.

Monoclonal antibodies are proteins produced in the laboratory that are designed to recognize specific targets on or within cancer cells. They then attach to these targets and either mark the cancer cells for destruction by other parts of the immune system, or directly block signals used by the cancer cells to survive and grow.

Checkpoint inhibitors are drugs that target proteins on T-cells (a type of white blood cell) which prevent them from recognizing and attacking cancer cells. By blocking these proteins, checkpoint inhibitors can help enhance an immune response against breast cancer.

Cytokine therapy is a type of treatment that uses naturally occurring substances in the body called cytokines. Cytokines can be injected into the body to help stimulate an immune response against breast cancer cells and promote tumor regression.

Adoptive cell therapies involve taking T-cells from a patient, modifying them in the laboratory to make them recognize and attach to cancer cells, then infusing them back into the patient. Adoptive cell therapies can help boost an immune response against breast cancer cells and may be useful for treating metastatic disease.

Immunotherapy has emerged as a promising treatment option for many types of cancer, including metastatic breast cancer. However, not all patients respond to immunotherapy, and it can be difficult to monitor the response in those who do receive treatment.

How to know if your treatment is working?

One way to monitor response to immunotherapy in metastatic breast cancer is through imaging studies such as computed tomography (CT) scans or magnetic resonance imaging (MRI). These imaging studies can provide information on tumor size and whether the tumor is shrinking, stable, or growing. However, changes in tumor size may not always be a reliable indicator of response to immunotherapy, as some patients may experience immune-related adverse events that can cause inflammation and swelling around the tumor, leading to an increase in tumor size even if the tumor is responding to treatment.

Another way to monitor response to immunotherapy is through biomarker analysis. Biomarkers are molecular or genetic signatures that can be measured in blood or tissue samples. In the context of immunotherapy, biomarkers such as tumor mutational burden (TMB), programmed death-ligand 1 (PD-L1) expression, and immune cell infiltration can be used to predict response to immunotherapy and monitor response over time.

TMB is a measure of the number of mutations present in a tumor, and tumors with high TMB are more likely to respond to immunotherapy. PD-L1 expression is a marker of immune evasion, and tumors that express high levels of PD-L1 may be more responsive to immunotherapy. Immune cell infiltration, as measured by the density of T cells or other immune cells within the tumor, can also be used to predict response to immunotherapy.

In addition to imaging and biomarker analysis, clinical assessment of symptoms and quality of life can also be used to monitor response to immunotherapy in metastatic breast cancer patients. Patients who are responding to immunotherapy may experience improvements in symptoms such as pain, fatigue, and difficulty breathing, as well as improvements in overall quality of life.

Overall, monitoring response to immunotherapy in the metastatic breast cancer setting requires a multifaceted approach that incorporates imaging studies, biomarker analysis, and clinical assessment of symptoms and quality of life. By using a combination of these methods, clinicians can more accurately assess response to treatment and tailor treatment strategies to individual patients.

What is Signatera?

Recently, a new technology called Signatera has been developed to look for circulating tumor DNA (ctDNA) in the blood of breast cancer patients. CtDNA is a form of genetic material that is shed from cancer cells into the bloodstream and can be used to monitor response to immunotherapy. Signatera uses next-generation sequencing technology to look for mutations in ctDNA that are unique to that patient’s tumor. This technology can be used to detect the presence of ctDNA and track changes in ctDNA over time, which can provide valuable information on response to immunotherapy. Signatera is an exciting new tool that has the potential to revolutionize the way we monitor response to immunotherapy in breast cancer patients. By providing a more accurate assessment of patient response, Signatera could improve clinical outcomes and lead to better treatment decisions for breast cancer patients receiving immunotherapy.

How does Signatera Work?

Signatera is a molecular test that uses ctDNA to monitor response to cancer therapy and detect residual disease in MBC patients undergoing immunotherapy. This technology allows for real-time tracking of the tumor’s genetic signature, allowing clinicians to make decisions about treatment more quickly and accurately than ever before. Signatera can also be used to measure minimal residual disease (MRD), which can predict recurrence or metastasis in MBC patients receiving immunotherapy. By monitoring ctDNA levels, Signatera has the potential to increase accuracy in treatment evaluation, improve patient outcomes and reduce healthcare costs associated with ineffective treatments.


Overall, breast cancer immunotherapy offers an exciting new approach to treating this disease and there are many different treatments available. We also understand that the uncertainty of a breast cancer diagnosis and anxiety of wanting to know if your treatment plan is working is real. Talk to your healthcare provider about which options might be right for you.

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