Feasibility of Near-infrared Photoimmunotherapy Combined With Immune Checkpoint Inhibitor Therapy in Unresectable Head and Neck Cancer

Background/Aim: Near-infrared photoimmunotherapy (NIR-PIT) is a recently developed cancer treatment modality that selectively kills cancer cells and may induce a therapeutic host immune response. The aim of this study was to determine the feasibility of combining NIR-PIT with immune checkpoint inhibitor (ICI) therapy for unresectable recurrent head and neck cancer. Patients and Methods: Five patients underwent NIR-PIT at Ryukyu University Hospital between January 2022 and April 2024. These patients had unresectable recurrent head and neck squamous cell carcinoma. Among these five patients, four received a combination NIR-PIT and pembrolizumab administration. Results: A total of seven lesions in the oropharynx and oral cavity were targeted. One patient was treated for three different target lesions. The best observed response (BOR) rate was 100%, with three complete responses and four partial responses. The most common treatment-related adverse event was Grade 1 or 2 local pain lasting one to two days postoperatively, which occurred in all patients. Grade 3 adverse events occurred in three cases (42.9%), including pneumonia, pharynx-cutaneous fistula, and trismus. Three patients received ICI therapy following NIR-PIT, achieving a 60% BOR rate. No immune-related adverse events were noted, and the aforementioned Grade 3 adverse events did not worsen during ICI therapy. At a median follow-up of 376 days (range=157-845 days), four target lesions showed no recurrence, while three had recurred. All five patients were alive, including three with no evidence of disease. Conclusion: The combination of NIR-PIT and ICI therapy for unresectable recurrent head and neck cancer was feasible.