Influence of Fractionation and Fluence Rate in Photodynamic Therapy with Photofrin or mTHPC

Geel, I. P. J. van; Oppelaar, Hugo; Marijnissen, Johannes P. A.; Stewart, F. A.

doi:10.2307/3579279

Cited by 72 publications

(37 citation statements)

References 16 publications

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“…In This is in agreement with a number of in vivo and in vitro studies [12][13][14][15][16][17][18][19][20][21].…”

Section: Autofluorescencesupporting

confidence: 92%

In Vitro Studies of Photosensitizer fluorescence changes on singlet oxygen mediated photobleaching

Atif

2013

J. Phys.: Conf. Ser.

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Abstract:The effects of photosensitizer concentration on the singlet oxygen mediated photobleaching have been investigated in keratinocytes. Cells having different photosensitizers concentration were identified on the basis of the fluorescence signal amplitude and their fluorescence decay then studied to see if there was a correlation with concentration. The experimental results shows that the photobleaching was more rapid at the higher concentration as compared to lower concentration which mean that singlet oxygen plays a vital role in the rapid m-tetrahydroxyphenylchlorin (mTHPC) induced fluorescence photobleaching causing the sensitizer to degrade.

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“…In This is in agreement with a number of in vivo and in vitro studies [12][13][14][15][16][17][18][19][20][21].…”

Section: Autofluorescencesupporting

confidence: 92%

In Vitro Studies of Photosensitizer fluorescence changes on singlet oxygen mediated photobleaching

Atif

2013

J. Phys.: Conf. Ser.

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“…Hua et al (1995) achieved a significantly increased tumour (transplanted rat mammary adenocarcinoma) doubling time using ALA when the light dose was modulated in a 30 s on/off protocol. Using mTHPC or Photofrin, van Geel et al (1996) found that only certain fractionation schedules were effective in limiting regrowth of a RIF-1 tumour model: for mTHPC, discontinuous irradiation with the 30 s on/off protocol proved effective at a fluence rate of 100 mW cm-2. The most likely mechanism is that the dark intervals are permitting reoxygenation of the partly treated tissue.…”

Section: Discussionmentioning

confidence: 99%

Photodynamic therapy of a transplanted pancreatic cancer model using meta-tetrahydroxyphenylchlorin (mTHPC)

MIkvy

Messman²,

MacRobert³

et al. 1997

Br J Cancer

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Summary Pancreatic cancer is difficult to treat, even for tumours localized to the pancreas. Photodynamic therapy (PDT) is a non-thermal technique for producing localized tissue necrosis with light after prior administration of a photosensitizing drug and it could have a role in the local treatment of these cancers. We studied PDT in a transplanted cancer in the hamster pancreas using the photosensitizer mTHPC (metatetrahydroxyphenylchlorin). Fluorescence microscopy showed maximum levels of mTHPC in normal pancreas 2-4 days after sensitization and in tumour at 4-5 days. For PDT, animals were given 0.1 or 0.3 mg kg-' mTHPC and the tumour was treated at laparotomy 2 or 4 days later with red light (50 J at 650 nm, continuous or fractionated) delivered via a single fibre touching the tumour surface. The maximum zone of tumour necrosis (seen 3 days after PDT) was 8.7 mm in diameter with continuous irradiation, increasing to 12.4 mm with light fractionation (four equal fractions with 3 min between fractions). The main complication was sealed duodenal perforation, seen in 3 of 16 animals, probably due to inadequate shielding of the duodenum from the light. The duodenal problems seen in hamsters are unlikely to cause trouble in the much thicker human duodenum. PDT tumour necrosis in this animal model has now been shown with a range of photosensitizers, but mTHPC is attractive as it is likely to produce the largest volumes of necrosis around each treatment point with short light exposure times. This technique could have a role in the treatment of localized cancers of the pancreas in patients unsuitable for surgery and can now be considered for preliminary clinical trials.

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“…The evidence to date suggests if oxygen levels can be maintained and/or increased prior to, during or after PDT [5] then the efficacy of PDT might be improved. A number of direct and indirect methods have been investigated to improve tissue oxygenation and potentially allow reoxygenation of the tumor including; hyperthermia [11], normobaric oxygen (NBO), oxygen multistep therapy, hyperbaric oxygen (HBO) [12], perfluorocarbons [13], light dose fractionation [14,15] and lowering of the light fluence rate [16].…”

Section: Introductionmentioning

confidence: 99%

Effect of an oxygen pressure injection (OPI) device on the oxygen saturation of patients during dermatological methyl aminolevulinate photodynamic therapy

et al. 2012

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Methyl aminolevulinate photodynamic therapy (MAL-PDT) (a topical treatment used for a number of pre-cancerous skin conditions) utilizes the combined interaction of a photosensitizer (protoporphyrin IX (PpIX)), light of the appropriate wavelength and molecular oxygen to produce singlet oxygen and other reactive oxygen species which induce cell death. During treatment localized oxygen depletion occurs and is thought to contribute to decreased efficacy.The aim of this study was to investigate whether an oxygen pressure injection (OPI) device had an effect on localized oxygen saturation levels and/or PpIX fluorescence of skin lesions during MAL-PDT. This study employed an OPI device to apply oxygen under pressure to the skin lesions of patients undergoing standard MAL-PDT. Optical reflectance spectrometry and fluorescence imaging were used to non-invasively monitor the localized oxygen saturation and PpIX fluorescence of the treatment area respectively. No significant changes in oxygen saturation were observed when these data were combined for the group with OPI and compared to the group that received standard MAL-PDT without OPI. Additionally no significant difference in PpIX photobleaching or clinical outcome at three months between the groups of patients was observed although the group that received standard MAL-PDT demonstrated a significant increase (p<0.05) in PpIX fluorescence initially and both groups produced a significant decrease (p<0.05) after light irradiation. In conclusion, with this sample size this OPI device was not found to be an effective method with which to improve tissue oxygenation during MAL-PDT. Further investigation is therefore required to find a more effective method of MAL-PDT enhancement.3

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Influence of Fractionation and Fluence Rate in Photodynamic Therapy with Photofrin or mTHPC

Cited by 72 publications

References 16 publications

In Vitro Studies of Photosensitizer fluorescence changes on singlet oxygen mediated photobleaching

In Vitro Studies of Photosensitizer fluorescence changes on singlet oxygen mediated photobleaching

Photodynamic therapy of a transplanted pancreatic cancer model using meta-tetrahydroxyphenylchlorin (mTHPC)

Effect of an oxygen pressure injection (OPI) device on the oxygen saturation of patients during dermatological methyl aminolevulinate photodynamic therapy

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