Breast Cancer: Exciting Advancements in Immunotherapy and Targeted Therapies

Every day, physician-researchers in Miami and around the world are increasing our understanding of breast cancer – what causes it, how it can be treated and what can be done to prevent it. They’re driving remarkable advances in breast cancer treatment and giving patients diagnosed with the disease more reason for hope.

Naomi Dempsey, M.D., and Ana Cristina Sandoval Leon, M.D., breast medical oncologists at Baptist Health Miami Cancer Institute, spoke recently about how breast cancer care is rapidly evolving from a “one size fits all” approach to one that uses targeted therapies. Such therapies are directed to the precise genetic makeup of a tumor’s cells and jumpstart the patient’s immune system to kill those cells.

Destroying cancer cells from the inside

Targeted drug therapy uses medicines that target proteins on breast cancer cells that help them grow, spread, and live longer. They work to destroy cancer cells or slow down their growth and have side effects different from chemotherapy.

Naomi Dempsey, M.D.,, breast medical oncologist at Baptist Health Miami Cancer Institute

Like chemotherapy, these drugs enter the bloodstream and reach almost all areas of the body, which makes them useful against cancers that have spread to distant parts of the body. Targeted drugs sometimes work even when chemotherapy drugs do not and can help increase the efficacy of other types of treatment.

Some targeted therapy drugs – monoclonal antibodies, for example – work in more than one way to control cancer cells and may also be considered immunotherapy because they help boost the immune system.

One specific type of targeted therapy is called immunotherapy, an exciting new advance in cancer care that is helping patients with many types of cancer. “Immunotherapy helps the immune system recognize the cancer as foreign and attack it. It works particularly well with chemotherapy because chemotherapy is killing the cancer and showing it to the immune system. Immunotherapy gives that immune system a boost,” says Dr. Dempsey, who sees patients at Miami Cancer Institute in Plantation.

"In patients with breast cancer, immunotherapy is currently only approved in patients with stage 2-3 (early-stage) triple-negative breast cancer and also for those with stage 4 metastatic triple negative breast cancer that is positive for a marker called PD-L1,” she says.

Ana Cristina Sandoval Leon, M.D., breast medical oncologist at Baptist Health Miami Cancer Institute

The main concern with immunotherapy is that it can activate the immune system too much, says Dr. Sandoval Leon. As a result, “patients can have different sorts of autoimmune problems and it can happen in any organ or system. So you can have rashes, inflammation of the heart, inflammation of the lungs, inflammation of the colon, among other side effects,” she says.

The main concern with immunotherapy is that it can activate the immune system too much, says Dr. Sandoval Leon. As a result, “patients can have different sorts of autoimmune problems and it can happen in any organ or system. So you can have rashes, inflammation of the heart, inflammation of the lungs, and inflammation of the colon, among other side effects,” she says.

Harnessing the combined power of different drugs

Depending on the patient and their cancer type and stage, immunotherapy is often used in conjunction with chemotherapy for even better outcomes. According to Dr. Sandoval Leon, who sees patients at Miami Cancer Institute in Miami, several other types of targeted therapy drugs can be used to treat breast cancer.

“We have monoclonal antibodies such as trastuzumab and pertuzumab that are being used to treat the HER 2 protein found on cancer cells in patients with HER 2 positive breast cancer,” Dr. Sandoval Leon explains. “We also have a rapidly emerging class of therapeutic agents known as antibody-drug conjugates, or ADCs, that combine the precision of a monoclonal antibody with a cytotoxin or type of chemotherapy. These have proven to be highly successful in treating multiple different types of breast cancer.”

There are more than a 100 new ADCs in clinical trials encompassing a wide variety of tumor types, according to Dr. Sandoval Leon. Trastuzumab deruxtecan, or T-DXd, is used for patients with HER2-positive or HER2-low breast cancer, she says, and is consistently performing better than conventional chemotherapy.  “We also have another ADC, sacituzumab govitecan, that we can use to treat hormone positive and triple negative metastatic breast cancer,” she adds.

Advancing science and improving outcomes

Clinical research is helping advance science and improve outcomes in patients with breast cancer, and both Dr. Dempsey and Dr. Sandoval Leon emphasize the value of these studies.

“Patients at Miami Cancer Institute have the opportunity of participating in a number of different clinical trials, and that’s extremely important because that is how we move the field forward,” says Dr. Sandoval Leon.

Dr. Dempsey echoes her colleague’s sentiments. “I encourage patients to keep an open mind regarding any clinical trials that they would be a good candidate for. There are a lot of benefits to being open to clinical trials. They give women access to potentially better therapies that are not yet widely available anywhere else,” she points out. “Plus, they’re not only helping themselves but also other cancer patients in the future.”

Dr. Dempsey says breast cancer treatment is entering an “exciting new era” of personalized medicine in which every patient gets the exact amount of treatment required in order to maximize efficacy and minimize toxicity.

“We don’t want to over-treat anybody and we don’t want to under-treat anybody, so we're really trying to understand your specific cancer,” Dr. Dempsey says. “What is its extent? Has it spread? If so, where, and what is feeding it? Then we can cut off those food sources, and that's where targeted therapy can be really useful.”