Abstract
BACKGROUND: Photoimmunotherapy (PIT) using cetuximab-sarotalocan sodium (CS) is a novel therapy for unresectable or locally recurrent head and neck squamous cell carcinoma (HNSCC). CS is a conjugate of cetuximab (monoclonal antibody targeting epidermal growth factor receptor [EGFR]) and IR700 (light-activatable dye). Intravenously administered CS binds to cancer cells expressing EGFR. Upon exposure to a 690 nm wavelength laser, the conjugated IR700 is photoactivated and induces a photochemical reaction that damages the tumor cells. While CS-PIT showed a favorable safety profile in an HNSCC clinical trial with no cases of drug-induced interstitial lung disease (DIILD), cetuximab is known to cause DIILD, especially in patients with pre-existing interstitial lung disease (ILD). CASE PRESENTATION: A 79-year-old man with recurrent HNSCC after surgery and adjuvant chemoradiotherapy received CS-PIT. Pre-treatment high-resolution chest computed tomography (HRCT) revealed mild ILD in the lower lobes of both lungs. Two months after CS-PIT, he developed severe DIILD with hypoxia. He received two cycles of intravenous methylprednisolone (1 g/day, 3 days/cycle) followed by oral prednisolone at 1 mg/kg/day, which was gradually tapered. After the high-dose corticosteroid therapy, the DIILD improved. CONCLUSION: We report the first case of DIILD caused by CS-PIT. Because cetuximab is a component of CS, CS-PIT has the potential to induce DIILD. Risk assessments and monitoring for DIILD are recommended for patients receiving CS-PIT.