May 2017 Ask the Expert: Immunotherapy
Immunotherapy, also called biologic therapy or biotherapy, uses the body’s own defenses to fight cancer. Immunotherapy medicines are in the early stages of testing in breast cancer. They are an exciting area of research that could have an impact on treatment in the future.
In May, Living Beyond Breast Cancer expert Sara M. Tolaney, MD, MPH answered your questions about immunotherapy and breast cancer. She addressed issues like how immunotherapy works, what types of breast cancer it may help treat, how to find and be part of an immunotherapy trial, and more.
Remember: we cannot provide diagnoses, medical consultations or specific treatment recommendations. This service is designed for educational and informational purposes only. The information is general in nature. For specific healthcare questions or concerns, consult your healthcare provider because treatment varies with individual circumstances. The content is not intended in any way to substitute for professional counseling or medical advice.
Immunotherapy is really a type of biologic therapy. There are other biologic therapies that are not immunotherapy agents.
There are currently no FDA-approved immunotherapy agents for breast cancer. There has been much work studying immunotherapeutic agents in breast cancer, with the majority of the initial focus being on triple-negative breast cancer (TNBC). Initial studies were done with pembrolizumab (an antibody against PD1) and atezolizumab (an antibody against PDL1). There are several other immunotherapies that are being investigated, including other PD1 antibodies (nivolumab, PDR001) and PDL1 antibodies (avelumab), agents targeting CTLA-4 (such as ipilimumab), and more novel agents that are focused on trying to stimulate the immune system.
The immune system’s job is to protect the body against developing cancer, but cancers try to evade the immune system by turning on various blockers. One of these blockers is PDL1. This puts the brakes on the immune system, and doesn’t allow it to effectively kill tumor cells. In order to overcome this, treatments were developed, such as antibodies against PDL1, that take the breaks off the immune system, and allow it to kill cancer cells.
There are not any known things that you could do to help stimulate your immune system to more effectively fight cancer outside of the immunotherapy agents that are currently being studied in breast cancer.
Generally, most immunotherapy agents are well tolerated, with the most common side effects being some fatigue, achiness, and sometimes fevers. There however can be rare and serious side effects. These can occur when the immune system starts thinking normal parts of your body are “foreign” and stimulates an immune reaction against it — in a similar way that patients can have autoimmune diseases. When the immune system does this, patients can have significant side effects — such as inflammation of the lungs, colon, thyroid, etc. These types of toxicities often require putting treatment with the immunotherapy on hold and treating with steroids to try to quiet the immune reaction and allow things to heal.
We generally don’t recommend doing anything to raise your white blood cell count if it is within the normal range. We don’t have data to suggest that a higher white blood cell count will help fight off the cancer.
It can be challenging to navigate clinical trial opportunities. If you look online at clinicaltrials.gov you can search for clinical trials that are specific to your subtype of cancer. It can still be hard to know for sure if you are eligible for these trials. We would be happy to see you at our institution [Dana-Farber Cancer Institute, in Boston] if you’d like to seek further consultation about opportunities — we do have immunotherapy trials open here for ER+, HER2+ and triple-negative breast cancer.
(Editor's note: For help finding trials you may be eligible for, check out LBBC's Metastatic Trial Search.)
Unfortunately, if you have an active autoimmune disorder requiring therapy, many immunotherapy trials will exclude you due to concerns about making your autoimmune syndrome worse. But there are a few ongoing studies looking at the safety of using these agents in patients with active autoimmune problems so we can learn more about the risks.
Cancer vaccines are designed to activate the immune system and direct it toward specific elements of the cancer. The vaccines are really trying to trigger an immune response against the tumor. There are some vaccines that are currently being studied in breast cancer, and are in clinical trials.
We are still learning more about which patients with breast cancer are likely to benefit from immunotherapy. Some of the original studies selected patients with breast cancer for immunotherapy by looking to see if their tumor had PDL1 expression. There is some data to suggest that response to immunotherapy agents by themselves may be higher in patients with PDL1+ tumors, but this doesn’t seem to be true when chemotherapy is administered with immunotherapy, as PDL1-positivity didn’t seem to be able to predict which patients would benefit. There are lots of biomarkers that are being explored to help us better select patients for therapy with immunotherapy, but we don’t have any answers at this time.
The FDA approved pembrolizumab (Keytruda) for patients with cancer (regardless of what body part the cancer is in) with metastatic microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) solid tumors that have progressed following prior therapy. (Normally our bodies are able to correct errors that occur when DNA is making copies of itself, but if tumors have the abnormalities mentioned above, they collect errors within them.)
This is very exciting as it is the first time the FDA has approved a treatment not based on where the tumor is in the body. Most of the data for this comes from testing pembrolizumab in patients with MSI-H colorectal cancers, so we don’t have much data on doing this in breast cancer. Additionally, the incidence of MSI-H or dMMR breast cancer is probably fairly low and we don’t have data yet on response to immunotherapy in breast cancer patients with MSI-H or dMMR tumors.
(Editor's note: Check out this article for more info on the FDA approval.)