e11548 Background: Photodynamic therapy (PDT) has been used for the treatment of many malignancies. This binary therapy involves the administration of a photosensitizer followed by exposure to light. Treatment toxicity has historically limited the use of PDT. Our study aimed to assess whether a novel approach, termed continuous low irradiance photodynamic therapy (CLIPT), would result in enhanced efficacy with reduced toxicity. Preclinical data suggest decreased toxicity and increased cell death by apoptosis with CLIPT. Methods: Breast cancer patients with chest wall progression were eligible for our study. No systemic anti-cancer therapy within 30 days and no radiation to the target site within 60 days of enrollment was allowed. All patients received porfirmer sodium intravenous 0.8mg/kg at time 0 and returned at time 48 hours for light exposure. A wavelength of 630nm was delivered continuously over 24 hours by a Diomed laser via a flexible light patch. An area of uninvolved normal skin was used as a control. Post-treatment biopsy was performed to assess for apoptosis by TUNEL assay. Results: Eight breast cancer patients were enrolled in our study. The initial dose of light was 100J/cm2 and was given to subjects 1 and 2 but resulted in partial-thickness ulceration of the epidermis. Subjects 3-8 received light at 50J/cm2 and experienced erythema at the intervention site, with no ulceration observed. All patients reported mild pain at the treatment site and 6 required short-term narcotic analgesia. Five of the 8 patients showed evidence of response, and no patients had progression of treated lesions. Four of 7 biopsy specimens showed evidence of apoptosis on TUNEL assay. Conclusions: CLIPT may prove to be a valuable option for treatment of breast cancer chest wall recurrence. The dose-limiting toxicity was skin ulceration and the maximum tolerated dose (MTD) was determined to be 50J/cm2/24h. A 50% response rate was seen in patients treated at the MTD, with apoptosis seen on post-treatment biopsy specimens. Further investigation of CLIPT as a therapeutic modality is warranted.
INTRAOPERATIVE PHOTODYNAMIC THERAPY IN GASTRIC CANCER PATIENTS
