Breast Cancer Awareness Month: How Immunotherapy Personalizes Treatment for This Common Cancer

Breast cancer is the second most common cancer among U.S. Women. When Breast Cancer Awareness Month was established in 1985, breast cancer was initially resistant to immunotherapy, considered “cold” and unresponsive. Nearly 40 years later, recent advances and clinical trials in immunotherapy are offering new hope, showing potential for better outcomes in breast cancer patients once considered untreatable with these methods.

Immunotherapy changed my life. It saved my life when I had no other options.”

Karen Peterson, CRI ImmunoAdvocate and breast cancer survivor

Advocating with Energy and Grace

Thanks to scientific breakthroughs, the five-year survival rate for breast cancer patients has reached 89 percent, and it rises to an incredible 99 percent when the cancer is caught early. This progress has transformed the lives of countless survivors, including Karen Peterson, a CRI ImmunoAdvocate. Karen now dedicates her time to supporting others, sharing her own treatment journey to inspire hope and strength in current patients facing similar challenges. It’s stories like hers that remind CRI just how powerful donor support is in driving life-saving advances.

“I’ve got a second chance to really take care of this body that I’ve worked so hard to keep and stay alive,” Peterson said in conversation with CRI. “I take the responsibility of being an ImmunoAdvocate very seriously.”

Immunotherapy was not her first-line treatment. When Peterson’s cancer returned and spread two years after she was treated with chemotherapy and surgery, she enrolled in a clinical trial. Peterson was eager for treatment and became the first triple-negative breast cancer (TNBC) patient in her immunotherapy trial.  Eight weeks later, a CT scan showed that her cancer had shrunk by nearly three-quarters of its original size. TNBC is the most aggressive form of breast cancer, with a higher risk of relapse and metastasis. Unlike other types of breast cancer, TNBC doesn’t rely on hormone signals for its rapid growth, making patients ineligible for hormone therapy. As a result, TNBC patients often face more intensive treatments, combining chemotherapy, radiotherapy, and surgery.

“Standard care didn’t work for me, but everybody’s cancer journey is different,” the Harlem, NY resident explained. She stressed that dealing with cancer involves nuance, and there is no standard rule book. “I feel the renewed energy of patients and caregivers who I speak to about my journey and what it was like to be in a clinical trial. Any emotions, any reactions that you are having are all normal. Give yourself grace and space.”

The Challenges and Opportunities of the Current Breast Cancer IO Landscape

For over 40 years, the Cancer Research Institute (CRI) has been at the forefront of breast cancer immunotherapy, driving innovation and hope. In the 2023-24 fiscal year alone, CRI invested over $4 million in the fight against this devastating disease. CRI-funded scientists are leading groundbreaking research, from tackling TNBC to developing a lactate-responsive drug delivery system that targets cancer metabolism. Their relentless dedication is transforming patient care and bringing us closer to life-saving therapies, offering renewed hope for a future without cancer.

Giulia Furesi, PhD, a CRI Postdoctoral Fellow at Washington University School of Medicine, is researching how a protein in the tumor environment called Osterix impacts the immune system’s ability to fight breast cancer. She explains that breast cancer is difficult to treat because it’s not a one-size-fits-all disease—it’s made up of many different types.

“One significant development has been the growing use of immune checkpoint inhibitors, particularly for TNBC,” she said. Checkpoint inhibitors are an immunotherapy that takes the ‘brakes’ off the immune system, allowing the treatment to target and attack cancer cells. “These inhibitors, which have succeeded in other cancers, are now offering hope for patients with TNBC.”

What’s Next on the Horizon

Sarah Sammons, MD, associate director of the Metastatic Breast Cancer Program at the Dana-Farber Cancer Institute, spoke in detail at CRI’s 2023 Annual Patient Summit about challenges and progress regarding breast cancer immunotherapy. Dr. Sammons noted that immunotherapy has made remarkable progress in the past decade and is now a first-line treatment for some breast cancer subtypes, including TNBC.

“Pembrolizumab (commonly known by its brand name, Keytruda®) with five months of chemotherapy before surgery for stage 2 and 3 TNBC has improved cure rates and has improved the pathological complete response,” she said during the patient summit. A pathological complete response means there are no traces of cancer in tissue examined after treatment. “These patients have a 93 to 94 percent chance of being cured of their cancer.”

Dr. Sammons stressed that clinical trials are crucial for discovering new treatments, as they are the pathway for approving drugs for all types of cancer. Currently, there are promising late-stage clinical trials for breast cancer patients, regardless of whether their tumors are PD-L1 positive or negative. PD-L1 is a protein on the surface of tumors that helps them avoid being targeted by the immune system.

Alongside TNBC, immunotherapy can also be effective in treating other breast cancers, as Dr. Sammons explains. “I’m very hopeful that patients with fast-growing hormone receptor-positive breast cancer may have an opportunity to get immunotherapy in the future. This is on the horizon.” Hormone receptors are proteins located on breast cancer cells, and they can latch on to estrogen or progesterone signals, promoting cancer cell growth. Eligible patients with tumors expressing these hormone receptors can be treated by using hormone antagonist drugs. With advancements in immunotherapy these patients will have more options of treatment available for them.

Thanks to the tireless research of scientists like Drs. Furesi and Sammons, and the dedicated advocacy of passionate breast cancer survivors like Karen Peterson, we are closer to creating a world immune to cancer.