To determine the safety, preliminary efficacy, pharmacokinetics, and immunogenicity of a single cycle of RM-1929 photoimmunotherapy, an anti-EGFR antibody cetuximab conjugated with a light-activatable dye (IRDye®700DX), in Japanese patients with recurrent head and neck squamous cell carcinoma (rHNSCC). Here, EGFR is linked to head and neck squamous cell carcinoma.