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Localization and treatment of transformed tissues using the photodynamic sensitizer 2‐[1‐hexyloxyethyl]‐2‐devinyl pyropheophorbide‐a
Author(s) -
Furukawa Kinya,
Yamamoto Hideki,
Crean David H.,
Kato Harubumi,
Mang Thomas S.
Publication year - 1996
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/(sici)1096-9101(1996)18:2<157::aid-lsm5>3.0.co;2-r
Subject(s) - photosensitizer , cheek pouch , photodynamic therapy , carcinogen , chemistry , hamster , cheek , fluorescence , pathology , cancer research , malignant transformation , medicine , photochemistry , surgery , biochemistry , physics , organic chemistry , quantum mechanics
Background and Objective Photofrin is the photosensitizer currently used in most clinical trials examining the efficacy of photodynamic therapy (PDT) for the treatment and/or palliation of neoplasia. Although this drug has been shown to be efficacious in many of these trials, it possesses less than ideal qualities for use in a systematically administered photosensitizer. A new photosensitizer, 2‐[1‐hexyloxyethyl]‐2‐devinyl pyropheophorbide‐a (HPPH), was developed for PDT. HPPH possesses more rapid clearance from skin and greater cytotoxicity per drug dose than Photofrin. The aims of this study were to: (1) examine the uptake and retention of HPPH in tissues undergoing malignant transformation using laser‐induced fluorescence, and (2) evaluate the efficacy of HPPH and 665 nm light in treating carcinogen‐induced tumors of the hamster buccal cheek pouch. Study Design/Materials and Methods The model of tissue transformation was the carcinogen (9,10‐dimethyl‐1,2‐benzanthracene)‐induced premalignant and malignant lesions of the hamster buccal cheek pouch. Following induction of the specific transformation stages, hamsters were injected intraperitoneally with 0.5 mg/kg HPPH. Subsequently, the buccal mucosa was examined for fluorescence at various times up to 72 hours after photosensitizer injection. Results Uptake studies of HPPH showed highest fluorescence levels in tissues 48 hours after HPPH injection. Fluorescence levels of tissues increased significantly as follows. Normal < dysplasia < papillomas < squamous cell carcinomas. Carcinogen‐induced tumors in 14 hamsters were treated with surface illuminations of red light (665 nm) via fiber optics coupled to an argon‐ion pumped dye laser 48 hours after intraperitoneal injection with either 0.5 or 1.0 mg/kg HPPH. Complete necrosis of tumor tissues 7 days following PDT was observed in 57% (4/7) with 0.5 mg/kg and 86% (6/7) with 1.0 mg/kg HPPH. Conclusions It appears that HPPH may be a promising photosensitizer for the detection and photodynamic treatment of transformed tissues. © 1996 Wiley‐Liss, Inc.