Foscan

Foscan is the brand name for temoporfin, a chlorin-based photosensitizing agent used in photodynamic therapy (PDT) for cancer. It is also referred to as mTHPC (meta-tetrahydroxyphenylchlorin). Temoporfin is administered intravenously and is characterized by high lipophilicity, which facilitates accumulation in tumor tissue.

Mechanism and use in PDT: When activated by red light, typically around 652 to 662 nanometers, temoporfin transfers energy to molecular oxygen to generate singlet oxygen and other reactive species. These reactive molecules cause damage to tumor cells, tumor vasculature, and can modulate local immune responses, leading to tumor destruction with localized effects.

Administration and regimen: The drug is given as an intravenous infusion, often at a dose of about 0.15 mg/kg. Light exposure is usually performed several days after administration, with a common interval of 96 hours (4 days) to allow selective tumor uptake. Light dosimetries and exact timing depend on guidelines and tumor location, but red light is standard for Foscan PDT.

Indications and applications: Foscan is indicated for the palliative treatment of advanced squamous cell carcinoma of the head and neck in adults, particularly in cases where surgery or radiotherapy are not feasible options. It is used to reduce tumor burden and symptoms in selected patients.

Safety and precautions: A major consideration with Foscan PDT is prolonged cutaneous and superficial photosensitivity, requiring avoidance of bright light exposure for several weeks after treatment (often reported as several weeks to a few months). Other adverse effects can include infusion-related reactions, nausea, fatigue, and local site reactions.

Research and status: Foscan has been studied in various PDT protocols and is approved in some regions for head and neck cancer. Its use and guidelines vary by country and clinical context.