FMT in Triple Negative Breast Cancer Guided by ctDNA

Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer, usually treated with chemotherapy and an immune checkpoint blockade (ICB) in the pre-operative or neoadjuvant phase. However, about 35% of tumors do not respond fully to this therapy, and patient prognosis is poor. Recent exciting data from our group and others suggest that the alteration of the gut microbiome via fecal microbiota transplantation (FMT) markedly affects the response to ICB in melanoma1-3. The investigators propose to test the safety and feasibility of altering the gut microbiome in the context of neoadjuvant therapy (NAT) for TNBC. This pilot study will assess the safety of FMT given with neoadjuvant chemo-immunotherapy and will determine the feasibility of conducting a future randomized clinical trial to test whether FMT improves the effectiveness of neoadjuvant chemotherapy and ICB in patients with TNBC.

This study will be divided into two phases. In Phase I (observational phase), the investigators propose to test the feasibility of collecting stool and plasma samples in TNBC patients treated with neoadjuvant therapy (NAT) without FMT treatment. In Phase II (interventional phase), patients will undergo the sample collection procedures as in Phase I, but in addition, the investigators will assess the safety and feasibility of FMT treatment in combination with NAT.