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Phase 2 Study of Aminolevulinic Acid Photodynamic Therapy Initiated in Barrett's Esophagus
Independent investigator studies have reported that orally administered ALA followed by red laser light selectively treats the epithelial (lining) layer of the esophagus, making it effective in ablating HGD without causing strictures (circumferential scarring) or prolonged skin photosensitivity. In DUSA's earlier small clinical trial on the removal of HGD in BE using Levulan PDT, patients received 60 mg/kg Levulan orally, followed 4 to 6 hours later by 200 J/cm2 of red laser light delivered through a clear balloon catheter. Of the 5 (of 6) patients that have been followed for a median of 12 months after the last Levulan PDT treatment (with an average of 2 treatments per patient), complete ablation of HGD was seen in all of them (100%), with no strictures reported.
In the new pilot Phase II clinical trial, at least 8 patients with HGD will receive 60 mg/kg Levulan orally, followed 4 to 6 hours later by 150 J/cm2 of 635 nm of red laser light delivered using DUSA's proprietary new endoscopic sheath device. The DUSA sheath device was designed in order to allow direct visualization of the target area for optimal placement of the light-carrying fiber optic. The design is also meant to deliver light evenly and circumferentially, all with only a single insertion of the endoscope. This compares with current methods of light delivery involving balloon catheterization which require multiple endoscope insertions and imprecise light placement.
Barrett's esophagus is an acquired condition affecting up to 700,000 patients in the United States, in which the normal esophageal lining is replaced by an abnormal lining that can then become dysplastic. Patients with confirmed high-grade dysplasia (HGD) often undergo major surgery to remove the affected portion of the esophagus. An alternative medical treatment for these patients using PDT was recently approved by the FDA. The approved drug, porfimer sodium (Photofrin®, Axcan Pharmaceuticals), was effective in Phase III clinical trials, but was associated with skin photosensitivity for up to 4 to 6 weeks, and strictures resulting in the need for repeated esophageal dilatation in 38% of the patients.
Stuart L. Marcus, MD, Ph.D., DUSA's CSO and CMO, stated "Published independent studies and DUSA's earlier small study have suggested a significant and prolonged effect of ALA PDT on dysplasia within BE. DUSA's new study will gather pilot treatment data using Levulan and DUSA's proprietary new endoscopic light delivery system, which we believe could lead to a simple, safe and effective treatment for this dangerous condition."
Source: Dusa Pharmaceuticals