Photosensitizing efficacy of MTHPC-PDT compared to Photofrin-PDT in the RIF1 mouse tumour and normal skin
✍ Scribed by Ingrid P. J. van Geel; Hugo Oppelaar; Yvonne G. Oussoren; Martin A. Der Van Valk; Fiona A. Stewart
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- French
- Weight
- 727 KB
- Volume
- 60
- Category
- Article
- ISSN
- 0020-7136
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✦ Synopsis
Abstract
The new photosensitizer, meso‐tetrahydroxyphenylchlorin (mTPHC) was compared with Photofrin in the murine RIF1 tumour and in normal mouse skin. A range of mTHPC or Photofrin doses were given at intervals of 1 hr to 7 days before illumination. mTHPC‐PDT resulted in much higher tumour phototoxicity with longer regrowth delays and more cures. The RIFI tumour could be effectively treated with 30 J cm^−1^ (interstitial illumination) at 1 day after mTHPC, whereas 4 to 13 times higher light doses were required with Photofrin for an equivalent anti‐tumour effect. High doses of mTHPC also caused more skin phototoxicity (superficial illumination) than Photofrin for the 1‐day illumination interval. Evaluating both tumour and normal skin photosensitization, the largest therapeutic gain factor (TGF) for mTHPC‐PDT was achieved with a low drug dose (0.15 mg kg^−1^) at 1 day before illumination (TGF = 5.6, relative to Photofrin PDT). The duration of cutaneous photosensitivity for mTHPC was shorter than for Photofrin. The light dose required to produce a desquamation response in 50% of the animals increased more than 20‐fold over the period 1 to 7 days after high doses of mTHPC, whereas this light dose only increased by a factor of 2 from 1 to 7 days after Photofrin. The large therapeutic gains seen for mTHPC‐mediated PDT compared to Photofrin, plus the rapid fading of skin photosensitization, suggest that mTHPC is a potent photosensitizer suitable for clinical testing. © 1995 Wiley‐Liss, Inc.