Squamous Cell Cancer

The goal of this Phase 1 clinical trial is to evaluate the safety and feasibility of nivolumab-IRDye800CW (nivo800) as a molecular imaging agent in adults with biopsy-confirmed or presumed head and neck squamous cell carcinoma (HNSCC) who are scheduled to undergo standard-of-care surgical resection. The main questions it aims to answer are: * Is nivolumab-IRDye800CW (nivo800) safe when administered before surgery, as measured by the occurrence of clinically significant Grade ≥2 adverse events that are possibly, probably, or definitely related to the study drug? * What is the extent of pathological response at each dose level, including residual viable tumor, fibrosis, necrosis, and tumor-infiltrating lymphocyte characteristics? Participants will: * Receive two intravenous infusions during the preoperative period, approximately 2-3 weeks before surgery and again 1-2 days before surgery. * Undergo standard-of-care surgical resection with collection of tumor and lymph node specimens for pathological and imaging studies.

The goal of this study is determine the safety and tolerability of orally taken probiotic (R-5780) in patients currently on a PD-1 Pathway Checkpoint Inhibitor (checkpoint protein on immune cells called T cells) with Solid Tumors.