Comparison of two routes of photosensitizer administration for photodynamic therapy of bladder cancer

Abstract

Photodynamic therapy (PDT) consists in administration of a photosensitizer and subsequent irradiation of the tumor with visible light. Routinely the photosensitizer is given intravenously (i.v.). The goal of our study was to examine whether intravesical (i.b.) instillation of the photosensitizer for PDT of bladder cancer might be feasible. Therefore, the uptake of chlor-aluminum-sulfonated phthalocyanine (CASPc) in bladder, bladder tumor, skin, and muscle in a rat bladder cancer model after i.v. injection and i.b instillation was compared. The efficacy of PDT after either method of administration was also evaluated. The CASPc concentration in bladder tumor after i.v. injection was approximately 1.5-fold that after i.b. instillation. The ratio of CASPc concentration between bladder tumor and normal bladder was approximately 2:1 after administration by either route. There was no systemic absorption of CASPc after i.b. instillation; hence no systemic side effects are expected. PDT showed similar effects on bladder tumor after either method of administration, but less side effects on normal bladder wall after i.b instillation. Our results demonstrate that i.b. instillation of CASP for PDT of superficial bladder cancer seems to have advantages over i.v. injection.