Triple-negative breast cancer (TNBC) is one of the most aggressive subtypes of breast cancer. Companies, research institutions, and nonprofits frequently collaborate on clinical trials for people with TNBC with the goal of improving breast cancer treatment.
Read more about how clinical trials work, what new types of treatment are currently being tested for TNBC, and the potential benefits and risks of joining a study.
TNBC grows quickly and lacks hormone receptors — estrogen receptors, progesterone receptors, and HER2 receptors — making it more difficult to target and treat than other types of breast cancer. TNBC also has a high rate of recurrence (relapse), compared to other types of breast cancer.
When you visit an oncologist after being diagnosed with TNBC, your doctor will prescribe certain medications approved by the U.S. Food and Drug Administration (FDA). These medicines have proven effectiveness in treating others through rounds of testing. Doctors follow specific dosing regimens that have shown the highest chances of successful outcomes.
For people with TNBC, doctors prescribe a regimen that may involve chemotherapy, radiation therapy, and/or an immunotherapy drug. They may also prescribe combination therapy, such as chemotherapy with immunotherapy, which may be called chemoimmunotherapy. Even though these drugs help many people, some types of cancer keep growing despite treatment.
Doctors, scientists, and people with TNBC are all eager to find drugs that work better. The good news for people with TNBC is that there are many clinical trials aimed at improving treatment. To get access to a drug that doesn’t yet have FDA approval, you need to be enrolled in a clinical trial.
If doctors want to find better treatment options, they need to test how well the new drugs work, the combinations and dosages that work best, and whether they work better in some people than others. To test these new drugs, doctors and scientists encourage people with breast cancer to enroll in clinical trials. These volunteers are usually randomly divided into two groups.
One group will receive currently approved medications, like chemotherapy or immunotherapies that are the standard treatment for TNBC, plus a new medication being tested. This group is the experimental group. The other group receives the standard, approved medications plus a placebo — a sugar pill or inactive substance. This is the control group. In clinical trials for cancer, all participants at least receive the current standard treatment regimen. You must be informed if there’s a chance you may receive a placebo.
Doctors then follow these individuals for a period of time, which may range from weeks to months or even years, to see if the new medicine improves their outcomes.
There are two major categories of clinical trials for TNBC. Some are testing immune-based therapies. Other trials are testing additional drugs that target specific genetic mutations (changes) in cancer cells.
Cancer cells suppress (weaken) a person’s immune system so they can divide and spread without hindrance. Some cancer drugs work by activating the immune system to identify and attack cancer cells. These types of drugs are called immunotherapy. Immunotherapy drugs work well in TNBC because they don’t rely on the hormone or protein targets present in other subtypes of breast cancer.
For example, pembrolizumab is an immunotherapy drug. It’s an antibody, or immune protein that can identify another protein and block it.
Pembrolizumab identifies and blocks a protein called programmed death-1 (PD-1) in immune cells called T cells. When PD-1 binds to cancer cells, it suppresses the immune system response. By blocking PD-1, pembrolizumab keeps T cells activated so they can kill the cancer cells.
Pembrolizumab, which has been referred to as a breakthrough treatment for TNBC, was approved after it helped people with TNBC live longer compared to chemotherapy drugs. Metastatic cancer means that the cancer has spread from its original location to other parts of the body. People with early-stage and metastatic triple-negative breast cancer can receive pembrolizumab with chemotherapy before surgery.
There are clinical trials to test new immune-based therapies, including new ways to combine immunotherapies with chemotherapy. One large clinical trial called I-SPY2 tested pembrolizumab and is currently testing new drugs such as cemiplimab and many drug combinations.
Atezolizumab is another immunotherapy drug that might work better than current treatments in some people with TNBC. This drug is also being tested in clinical trials in people with both early-stage and more advanced and metastatic TNBC.
Not all people with TNBC are eligible to receive immunotherapy, and not all people will benefit from immunotherapy. If you don’t meet the criteria for those clinical trials, there are other options.
There are trials for medicines that work by targeting a specific genetic mutation in cancer cells. For example, some people with TNBC have a mutation in the BRCA1 or BRCA2 genes. BRCA mutations are only one example of mutations found in breast cancer cells, but there are many others.
Depending on your prognosis (outlook), your doctor might recommend genetic testing of your cancer cells — particularly if you're older than 60 and have TNBC.
Several clinical trials are testing drugs in people with TNBC to see if a new therapy regimen works better than chemotherapy alone in people with a certain genetic mutation. One potential immune-based therapy called durvalumab targets the BRCA1 mutation. Durvalumab is being tested in combination with olaparib (Lynparza). Olaparib is in a group of oral drugs called PARP inhibitors, which are designed to target specific aspects of cancer.
Everyone’s cancer is different, so there are many possible combinations of drugs that might work best. Clinical trials are essential to discover the best combinations.
If you’re interested in joining a clinical trial, the first step is talking to your doctor and cancer care team. They’ll help you check whether you’re eligible to participate in any ongoing or upcoming clinical trials. Apart from your doctor or hospital, cancer organizations like the American Cancer Society keep a list of clinical trials you may be eligible for. Several online databases, like ClinicalTrials.gov, list many ongoing and planned clinical trials for TNBC.
All drugs have potential side effects, even those sold over the counter, and there are risks to using a drug that’s still being tested. However, a new treatment might be more effective for you than previous medicines. You can withdraw from a clinical trial at any time.
There’s no guarantee that being part of a clinical trial will cure your disease, but it might be an opportunity to receive cutting-edge treatment. Your breast cancer specialist knows the details of your condition best, and they can help you decide whether the potential benefits of participating in a clinical trial outweigh the potential risks.
If you decide to join a clinical trial, your participation can help advance breast cancer research, bringing better treatment options to more people in the future. Additionally, by participating, you gain access to cutting-edge therapies and personalized care.
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