A Phase 2a, Single-dose, Open-label Study to Evaluate Diagnostic Performance and Safety of Pegsitacianine, an Intraoperative Fluorescence Imaging Agent for the Detection of Cancer, in Patients With Unknown Primary Head and Neck Cancer (ILLUMINATE STUDY)

This is a non-randomized, open-label, single-center, safety and imaging feasibility study of Pegsitacianine, an intraoperative fluorescence imaging agent. The main purpose of this study is to investigate whether Pegsitacianine can be used to image head and neck cancers as well as unknown primary cancer of the head and neck 6-300 hours post dose in patients undergoing routine surgery for biopsy, evaluation, detection or removal of their primary cancer. The study consists of two Parts. * Part 1 will be performed in a single dose of 1 mg/kg given such that Pegsitacianine fluorescence can be used to image primary tumors in patients with HNSCC undergoing routine surgery at 6-300 hours, and if needed at an alternate imaging schedule post dose. * Part 2 will be performed in a single dose of 1 mg/kg given such that Pegsitacianine fluorescence can be used to image primary tumors in patients with unknown primary cancer of the head and neck (UPC) at 6-300 hours, and if needed at an alternate imaging schedule post dose.