In the Phase 3 KEYNOTE-522 clinical trial, researchers found that pembrolizumab was effective in treating patients with triple-negative breast cancer (TNBC). According to Medical XPress, researchers wanted to determine whether immunotherapy, in conjunction with chemotherapy, benefited patients prior to surgical tumor resection. There was a particular focus on those with early-stage TNBC, which is considered Stage 2-3. Ultimately, the research highlighted how adding pembrolizumab to chemotherapy significantly reduced the risk of TNBC recurrence.

If you’d like to learn more, you can take a look at the findings published in the New England Journal of Medicine. 

About the Research into TNBC

Altogether, 1,174 participants enrolled within the KEYNOTE-522 trial. During the trial, patients either received pembrolizumab and chemotherapy, or a placebo and chemotherapy. This continued following surgeries. 

The National Cancer Institute (NCI) defines pembrolizumab as: 

A humanized monoclonal immunoglobulin (Ig) G4 antibody directed against human cell surface receptor PD-1 (programmed death-1 or programmed cell death-1). Upon administration, pembrolizumab binds to PD-1, an inhibitory signaling receptor expressed on the surface of activated T cells, and blocks the binding to and activation of PD-1 by its ligands, which results in the activation of T-cell-mediated immune responses against tumor cells.

In short, pembrolizumab binds to PD-1, which makes it easier to identify and destroy cancerous cells. Pembrolizumab is currently approved to treat a variety of cancers, including cervical cancer, cutaneous squamous cell carcinoma (cSCC), melanoma, renal cell carcinoma (RCC), and more. 

Within this trial, researchers found that pembrolizumab reduced the risk of TNBC recurrence by 37%, and also reduced the risk of developing a secondary breast cancer by 39%. This is particularly important as TNBC is notoriously difficult to treat. Therefore, pembrolizumab offers a way to help improve patient outcomes and overall survival. 

Understanding Breast Cancer

As the name suggests, breast cancer forms in the breast tissue. While an estimated 10% of breast cancer diagnoses result from BRCA gene mutations, the remainder of causes are unknown. Risk factors include being female, being older in age, having a family history of breast cancer, being obese, having early menstruation or late menopause, alcohol use, never having been pregnant, or having children at an older age. While breast cancer is the second most common cancer in women, it can affect people across the gender spectrum. 

Triple-negative breast cancer (TNBC) is often aggressive, recurrent, and difficult-to-treat. BreastCancer.org explains that TNBC is HER2-negative, estrogen receptor-negative, and progesterone-receptor negative. This causes TNBC to not respond to typical treatments. TNBC is more common in women younger than 40, women with BRCA1 mutations, and Black women. 

Symptoms associated with TNBC include:

• Nipple or breast pain
• Inverted nipples
• Breast inflammation
• A lump or mass felt in the breast
• Swollen lymph nodes
• A change in the breast’s size, shape, or appearance
• Nipple discharge
• Skin dimpling
• Peeling, scaling, crusting, flaking, reddened, or pitted breast skin