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Background: Most patients with esophageal and esophago-gastric junction cancers present with locally advanced or advanced disease. Dysphagia is the predominant symptom in 80-96% of patients and 42-46% experience significant weight loss due to luminal obstruction caused by the tumor. Esophageal stenting permits rapid relief of dysphagia, but is associated with pain, bleeding, migration, and food-impaction and has no impact on overall survival. Photodynamic therapy with porfimer sodium is approved in the USA for palliation of obstructing esophageal cancer but is rarely used due to prolonged skin photosensitivity. A new form of PDT using a Bacteriochlorophyll derivative (WST11) has rapid clearance, resulting in reduced skin photosensitivity and has gained interest because of animal studies suggesting that tumor destruction is associated with immune effects that can be augmented with selective immunosuppressants and checkpoint inhibitors.
Methodology: We initiated a Phase 1 study to determine the maximally tolerated laser light fluence rate (mW/cm) of light exposure for VTP treatment of obstructing esophagogastric cancer using a fixed drug dose of WST11. This is a preliminary assessment of results.
Results: Eight patients have been treated thus far, 3 at a fluence rate of 150 mW/cm, 3 at 200 mW/cm and 2 at 250 mW/cm. There have been no dose limiting toxicities thus far and only 3 serious adverse events consisting of 2 patients with tumor associated bleeding requiring blood transfusions, and one patient with chest pain and nausea requiring hospitalization and medical therapy for 24 hours.
Visible signs of tumor necrosis have been observed at each fluence rate, with objective improvement in dysphagia in one patient at 150 mW/cm, 2 patients at 200 mW/cm and 1 of 2 patients treated at 250 mW/cm.
Conclusion: Although it is still early in the study, luminal therapy with WST11 VTP seems to be safe and may provide partial tumor destruction with short-term relief of dysphagia in patients with obstructing esophago-gastric cancer.
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