Triple Negative Breast Cancer (TNBC) means the cancer does not have certain common receptors, making it harder to treat. This study looks at how a treatment called neoadjuvant chemo-immunotherapy affects the immune system and cancer in people with early-stage TNBC. Neoadjuvant treatment is therapy given before the main treatment to shrink the tumor. Pembrolizumab is a medicine used to help the immune system attack cancer cells. The study checks if this treatment makes helpful changes in the blood and cancer tissue. Researchers will see if a specific immune response, called a pro-inflammatory cytokine milieu, is created by the treatment and if it helps to remove the cancer completely.

• The study is for people with newly diagnosed Stage II-III TNBC who haven't had any treatment yet.
• You must be willing to follow all study procedures and visits.
• Participants can't be pregnant or on certain medications that might interfere with the study.