Response of Photofrin®-sensitised mesothelioma xenografts to photodynamic therapy with 514 nm light

Foster, Thomas H.; Sl, Gibson; Raubertas, R. F.

doi:10.1038/bjc.1996.184

Cited by 16 publications

(9 citation statements)

References 13 publications

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“…This corresponds to a value of 0.77 ± 0.1 μ M s −1 mW −1 cm 2 at 630 nm, which is the typical wavelength used for clinical Photofrin‐PDT. This calculation was based on the fact that Photofrin extinction is approximately three times greater at 514 nm than it is at 630 nm (25,26). Through the reanalysis of the data we also obtained new values of 12.1 ± 3.4 μ M and 56.5 ± 8.6 M −1 for the parameters, k p / k ot and k os / k os [ A ], respectively.…”

Section: Resultsmentioning

confidence: 99%

Photophysical Parameters, Photosensitizer Retention and Tissue Optical Properties Completely Account for the Higher Photodynamic Efficacy of meso‐Tetra‐Hydroxyphenyl‐Chlorin vs Photofrin^¶

Mitra

Foster

2005

Photochem & Photobiology

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Meso‐tetra‐hydroxyphenyl‐chlorin (mTHPC) is one of the most potent photosensitizers currently available for clinical photodynamic therapy (PDT). However the reason or reasons for its high photodynamic efficacy remain(s) unresolved. To investigate the PDT efficacy of mTHPC vs Photofrin we use the knowledge of photophysical parameters extracted from the analysis of oxygen electrode measurements in spheroids to compute and compare their respective singlet oxygen (1O2 dose depositions. The electrode measurements indirectly report the bleaching kinetics of mTHPC and indicate that its photobleaching mechanism is consistent with 1O2‐mediated reactions. mTHPC's photodegradation via1O2 reactions is confirmed by a more direct evaluation of the spatially resolved fluorescence in confocal sections of intact spheroids during irradiation. The PDT efficacy comparisons establish that mTHPC's enhanced potency may be accounted for completely on the basis of its ability to sequester tightly in cells and its photophysical properties, in particular its higher extinction coefficient at a redshifted wavelength. We extend the efficacy comparison to include the influence of hemoglobin absorption of PDT treatment light and show that incorporating the influence of wavelength‐dependent light attenuation in tissue further contributes to significantly higher efficacy for mTHPC‐ vs Photofrin‐PDT.

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Section: Resultsmentioning

confidence: 99%

Photophysical Parameters, Photosensitizer Retention and Tissue Optical Properties Completely Account for the Higher Photodynamic Efficacy of meso‐Tetra‐Hydroxyphenyl‐Chlorin vs Photofrin^¶

Mitra

Foster

2005

Photochem & Photobiology

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“…to avoid wall perforation in PDT of hollow organs, such as bronchi, esophagus and large bowel). Support for this idea was obtained from dual‐wavelength PDT measurements (25–27). Some of these seem to bear out the assumption that depth of tumor eradication is correlated with depth of light penetration, δ(λ), but others do not.…”

Section: Discussionmentioning

confidence: 99%

Wavelength-dependent Properties of Photodynamic Therapy Using Hypericin in vitro and in an Animal Model¶

Blank

Kostenich²,

Lavie

et al. 2007

Photochemistry and Photobiology

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Wavelength effects in photodynamic therapy (PDT) with hypericin (HY) were examined in a C26 colon carcinoma model both in vitro and in vivo. Irradiation of HY‐sensitized cells in vitro with either 550 or 590 nm caused the loss of cell viability in a drug‐ and light‐dose–dependent manner. The calculated ratio of HY‐based PDT (HY‐PDT) efficiencies at these two wavelengths was found to correlate with the numerical ratio of absorbed photons at each wavelength. In vivo irradiation of C26‐derived tumors, 6 h after intraperitoneal administration of HY (5 mg/kg), caused extensive vascular damage and tumor necrosis. The depth of tumor necrosis (d) was more pronounced at 590 than at 550 nm and increased when the light dose was raised from 60 to 120 J/cm2. The maximal depths of tumor necrosis (at 120 J/cm2) were 7.5 ± 1.5 mm at 550 nm and 9.9 ± 0.8 mm at 590 nm. Both values are rather high in view of the limited penetration of green‐yellow light into the tissue. Moreover, the depth ratio, d590/d550= 1.3 (P < 0.001), is smaller than expected considering the 2.2‐fold lower HY absorbance and the 1.7‐fold lower tissue penetration of radiation at 550 than at 590 nm. This finding indicates that in vivo the depth at which HY‐PDT elicits tumor necrosis is not only determined by photophysical considerations (light penetration, number of absorbed photons) but is also influenced significantly by other mechanisms such as vascular effects. Therefore, despite the relatively short‐wavelength peaks of absorption, our observations suggest that HY is an effective photodynamic agent that can be useful in the treatment of tumors with depths in the range of 1 cm.

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“…Because oxygen depletion results from the rate of photon absorption by the photosensitizer and not irradiance per se , a subsequent higher irradiance would be an efficient means of delivering increased fluence without oxygen depletion. We are aware of only one preclinical evaluation of a stepped irradiance protocol 24.…”

Section: Discussionmentioning

confidence: 99%

A retrospective review of pain control by a two‐step irradiance schedule during topical ALA‐photodynamic therapy of non‐melanoma skin cancer

et al. 2013

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Background and Objective Photodynamic therapy (PDT) with topical δ-aminolevulinic acid (ALA) of non-melanoma skin cancers is often associated with treatment-limiting pain. A previous study on basal cell carcinomas (BCCs) at Roswell Park Cancer Institute evaluated a two-step irradiance scheme as a means of minimizing pain, preserving outcomes, and limiting treatment time. We used an initial low irradiance until 90% of the protoporphyrin IX was photobleached, followed by a high irradiance interval until the prescribed fluence was delivered. Success of this pilot investigation motivated integration of the protocol into routine practice. Here we present a retrospective review of recent clinical experience in a broad patient population. Study Design/Materials and Methods This was a retrospective review of an existing dermatology data base. Fourteen caucasion patients - 9 men and 5 women, ages 18 to 80, with a total of 51 superficial and 73 nodular BCCs, and three Bowen's disease lesions – were included. ALA was applied to each lesion for approximately 4h. Lesions received an initial irradiance of 30 - 50 mW/cm2 for 20 J/cm2, followed by 150 mW/cm2 for a total fluence of 200-300 J/cm2. Pain was assessed using a visual analog scale (VAS). Clinical outcome was determined at 6-12 months. Results Median VAS scores were 1.0 for both irradiances. Five of 127 lesions required pain control with 1% xylocaine. Pain was strongly influenced by lesion location but not by lesion type, number, or size. Complete responses were achieved in 84.1% of BCCs, which compares favorably with reported results for single ALA-PDT treatments. Two of three Bowen's disease lesions showed a complete response. Complete responses for nodular BCCs were 37%, which are also within the range of reported outcomes. Conclusions A two-step irradiance protocol in ALA-PDT effectively minimizes pain, maintains excellent clinical outcomes in superficial lesions, and adds minimal treatment time.

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Response of Photofrin®-sensitised mesothelioma xenografts to photodynamic therapy with 514 nm light

Cited by 16 publications

References 13 publications

Photophysical Parameters, Photosensitizer Retention and Tissue Optical Properties Completely Account for the Higher Photodynamic Efficacy of meso‐Tetra‐Hydroxyphenyl‐Chlorin vs Photofrin^¶

Photophysical Parameters, Photosensitizer Retention and Tissue Optical Properties Completely Account for the Higher Photodynamic Efficacy of meso‐Tetra‐Hydroxyphenyl‐Chlorin vs Photofrin^¶

Wavelength-dependent Properties of Photodynamic Therapy Using Hypericin in vitro and in an Animal Model¶

A retrospective review of pain control by a two‐step irradiance schedule during topical ALA‐photodynamic therapy of non‐melanoma skin cancer

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Response of Photofrin®-sensitised mesothelioma xenografts to photodynamic therapy with 514 nm light

Cited by 16 publications

References 13 publications

Photophysical Parameters, Photosensitizer Retention and Tissue Optical Properties Completely Account for the Higher Photodynamic Efficacy of meso‐Tetra‐Hydroxyphenyl‐Chlorin vs Photofrin¶

Photophysical Parameters, Photosensitizer Retention and Tissue Optical Properties Completely Account for the Higher Photodynamic Efficacy of meso‐Tetra‐Hydroxyphenyl‐Chlorin vs Photofrin¶

Wavelength-dependent Properties of Photodynamic Therapy Using Hypericin in vitro and in an Animal Model¶

A retrospective review of pain control by a two‐step irradiance schedule during topical ALA‐photodynamic therapy of non‐melanoma skin cancer

Contact Info

Product

Resources

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Photophysical Parameters, Photosensitizer Retention and Tissue Optical Properties Completely Account for the Higher Photodynamic Efficacy of meso‐Tetra‐Hydroxyphenyl‐Chlorin vs Photofrin^¶

Photophysical Parameters, Photosensitizer Retention and Tissue Optical Properties Completely Account for the Higher Photodynamic Efficacy of meso‐Tetra‐Hydroxyphenyl‐Chlorin vs Photofrin^¶