In our previous study, we discovered that an immunotoxin (IT) composed of an anti-ROBO1 antibody linked to saporin, when administered in conjunction with the photosensitizer (PS) disulfonated aluminum phthalocyanine (AlPcS2a) and exposed to light at a wavelength of 680 nm, potentiates cytotoxicity in head and neck squamous cell carcinoma (HNSCC) cells. This evidence concerns the gene ROBO1 and head and neck squamous cell carcinoma.