This clinical trial is focused on patients with early-stage triple-negative breast cancer who have shown a strong response to initial treatments. The study is examining the use of a medication called pembrolizumab, which is given as a solution through an intravenous infusion. Pembrolizumab is a type of treatment that helps the immune system fight cancer cells. The trial aims to determine if simply observing patients after surgery is as effective as continuing treatment with pembrolizumab for six months in preventing the cancer from coming back.

Participants in the study will have already received standard chemotherapy and pembrolizumab before surgery and achieved a complete response, meaning no signs of cancer were found in the breast or lymph nodes. The study will compare two groups: one group will continue to receive pembrolizumab after surgery, while the other group will be closely monitored without further treatment. The goal is to see if both approaches offer similar protection against the cancer returning.

The trial will also look at the safety and side effects of pembrolizumab, as well as the overall quality of life of the participants. This includes monitoring for any new symptoms or health issues that may arise during the study. The study is expected to continue for several years to gather enough information to make a clear comparison between the two approaches. Participants will be regularly checked to ensure their health and well-being throughout the study period.