While Photofrin PDT is approved oncological therapy for multiple indications, its wider use is hindered by prolonged skin photosensitivity lasting several weeks. The aim of this study is to investigate intratumoral Photofrin administration as a way to decrease skin photosensitivity compared to the standard IV injection protocol. Tumor necrosis after PDT was assessed with immunohistochemical staining and Photofrin distributions by fluorescence microscopy.
Laser model: ML7710
Wavelength: 630 nm
Power: 400 mW/cm2
Fluence: 100 J/cm2
Drug light interval:
0.25 h (for intratumoral)
or 48 h (for IV)
Intratumoral drug administration
|Route of administration||Photofrin dose (mg/kg)||Average tumor necrosis (mm)||Average skin photosensitivity|
|Intratumoral (n=14)||0.5||6.8 ± 1.3||Little to no|
|1||7.8 ± 1.4|
|2||5.8 ± 1.6|
|Intravenous (n=9)||2||5.5 ± 2.1||Evident reddening & swelling|
Anti-tumor efficacy was similar between intratumoral and IV administration, however smaller doses of Photofrin were required to achieve comparable efficacy in case of intratumoral administration. Also significantly shorter drug-light interval with intratumoral administration can be convenient in the clinical setting, compared to 40-50 h interval required with IV administration to allow drug clearance from the normal tissues. Intratumoral administration also led to more localized drug distribution with minimal skin photosensitivity. In case of IV injection, redness and swelling of the paws and ears was observed as well as increased skin fluorescence at the tumor site and remote sites relating to systemic distribution of the photosensitizer.
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Photofrin® photodynamic therapy with intratumor photosensitizer injection provides similar tumor response while reducing systemic skin photosensitivity: Pilot murine study
Timothy M. Baran PhD
Lasers Surg Med., 2018, 50 (5)
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