Abstract
Introduction: Photodynamic therapy (PDT) is used to treat early proximal bronchial cancer during a flexible bronchoscopy. The technique relies on the excitation of a photosensitizer by an appropriate wavelength, which is delivered into the bronchus in close contact with the tumor.
Objective: To assess methylene blue (MB) as a PDT agent for the treatment of lung cancer in preclinical models.
Methods: MB induced PDT was performed on cancerous lesions obtained both in the cheek pouch model, and on NCI-H460 tumoral xenografts in nude mice. Bilateral tumors were induced in each animal. PDT was carried out on right-sided tumors after intratumoral injection of methylene blue 1% (w/v) and illumination at 630 nm at 200 J/cm (Diomed PDT 630). The left tumor was used as control (illumination alone or methylene blue alone). The tumoral volume was assessed before and 15 days after PDT.
Results: Nine carcinomas were treated in the cheek pouch model. MB-PDT produced a mean volume decrease of 85.8% (from 44.8% to 100%) (initial mean volume = 210 mm3 vs. final mean volume = 97 mm3). Histology analysis showed 4/9 complete responses.
14 xenografts were treated in mice, including 7 treated with MB-PDT, producing a 52% mean tumor volume regression (1568mm3 vs. 544mm3) compared to 7 controls in which tumor volume increased (p=0.007, Mann-Whitney test).
Conclusion: Topical methylene blue appears unexpensive and efficient as PDT agent for lung cancer treatment. Further studies are needed to assess the safety and efficacy of MB-associated PDT for the treatment of cancerous bronchial lesions in humans.
Financial support: French Ligue nationale against Cancer (Seine maritime and Eure Commitees) and ADIR, Rouen France.
- © 2013 ERS