The Intestinal Microbiome in Triple Negative Breast Cancer Treated with Immunotherapy

Inclusion Criteria:

* Age ≥18 years
* Female biological sex
* Newly diagnosed, previously untreated, histologically confirmed early triple-negative breast cancer
* Plan to initiate preoperative anti-PD-1 immunotherapy using pembrolizumab
* Overweight or obesity, defined as a body mass index \>=25 kg/m2
* Ability to provide written informed consent
* Allow the collection and storage of biospecimens and data for future use

Exclusion Criteria:

* Active autoimmune disease
* Concomitant conditions that require the use of antibiotics (e.g., chronic sinusitis)
* Digestive disease disorders (e.g., irritable bowel syndrome, Crohn's disease)
* Currently pregnant, breastfeeding, or planning to become pregnant within the next 24 weeks
* Recent (within 90 days) use of glucocorticoids for more than 10 consecutive days
* Any other cardiovascular, pulmonary, orthopedic, neurologic, psychiatric, or other condition that, in the investigator's opinion, would preclude participation or successful compliance with the protocol
* Any other situation that, in the opinion of the investigator, would negatively impact subject safety or successful compliance with the protocol