Photodynamic therapy (PDT) mediated with vascular acting photosensitizer pd-bacteriopheophorbide (Tookad), is investigated as an alternative modality for the total ablation of prostate cancer. Invivo normal canine prostate is used as the animal model. Interstitial PDT was performed by irradiating the surgically exposed prostates with a diode laser (763 nm, 150 mW/cm) to activate the i.v. infused photosensitizer drug. The effects of two-session PDT were evaluated. The prostate and its adjacent tissues were harvested and subjected to histopathological examination. At one-week, post second-session PDT, the animals recovered well with little or no urethral complications. Prostatic urethra and prostate adjacent tissues (bladder and underlying colon) were well preserved. Two-session PDT or one single session PDT induced a similar extent of damage. PDT induced prostate lesions were characterized by marked hemorrhagic necrosis. Maximum lesion size of over 3 cm in dimension could be achieved with a single 1-cm interstitial treatment, suggesting the therapy is very effective in ablating prostatic tissue. Pharmacokinetic studies show that the photosensitizer is cleared rapidly from the circulation. In conclusion, the novel photosensitizer Tookad mediated PDT may provide an effective alternative to treat prostate cancer.
In this study, photodynamic therapy (PDT) mediated with a novel, second generation photosensitizer Tookad (palladium-bacteriopheophorbide, WST09, STEBA Biotech, France), is investigated as an alternative modality in the treatment of prostate cancer. In vivo normal canine prostate and spontaneous advanced prostate cancer are used as the animal model. PDT was performed by irradiating the surgically exposed prostates with a diode laser (763 nm, 150 mW/cm) to activate the i.v. infused photosensitizer. The effects of drug concentration, drug-light interval, and light fluence rate on the PDT efficacy were studied. The prostates and adjacent tissues (bladder and underlying colon) were harvested and subjected to histopathological examination. During the one-week to 3-month period post PDT treatment, the dogs recovered well with little or no urethral complications. Prostatic urethra and prostate adjacent tissues (bladder and underlying colon) were well preserved. Light irradiation delivered during drug infusion or within 15 min post drug infusion induced the similar extend of damages. PDT induced prostate lesions in both normal and cancerous prostate were characterized by marked hemorrhagic necrosis and atrophy. Maximum lesion size of over 3 cm in dimension could be achieved with a single 1-cm interstitial treatment, suggesting the therapy is very effective in ablating cancerous prostatic tissue. In conclusion, the second generation photosensitizer Tookad mediated PDT may provide an effective alternative to treat prostate cancer.
Photodynamic therapy (PDT) utilizes optical energy to activate a pre-administered photosensitizer drug to achieve a localized tumor control. In the presented study, PDT mediated with a second-generation photosensitizer, WST09 (TOOKAD, Steba Biotech, The Netherlands), is investigated as an alternative therapy in the treatment of prostate cancer. In vivo canine prostate is used as the animal model. PDT was performed by irradiating the surgically exposed prostates both superficially and interstitially with a diode laser (763 nm) to activate the intra-operatively i.v. infused photosensitizer. During light irradiation, tissue optical properties, and temperature were monitored. During the one-week to 3-month period post PDT treatment, the dogs recovered well with little or no complications. The prostates were harvested and subjected to histopathological evaluations. Maximum lesion size of over 3 cm in dimension could be achieved with a single treatment, suggesting the therapy is extremely effective in destroying prostatic tissue. Although we found there was loss of epithelial lining in prostatic urethra, there was no evidence it had caused urinary tract side effects as reported in those studies utilizing transurethral irradiation. In conclusion, we found second generation photosensitizer WST09 mediated PDT may provide an excellent alternative to treat prostate cancer.
MSH receptors are one of the possible targets to specifically attack melanoma cells by photodynamically active agents bound to melanotropic hormones. To attack effectively metastatic melanoma the presence of the hormone receptor has to be proven in metastases. Radioactive labeling of melanotropic hormones allows us to check for the presence of intact receptors. We tried to develop a non-radioactive immunological method as a first step to work out therapeutic strategies to attach photodynamically active porphyrins to the surface of melanoma cells.
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