HPD photoradiation therapy for cancer at Kingston and Hamilton

In vitro and in vivo effects of photodynamic therapy on murine malignant melanoma

BACKGROUND

The role of photodynamic therapy (PDT) in the treatment of malignant melanoma is not well defined, nor is it known whether the dark melanoma cells absorb the light used in PDT.

METHODS

IN VITRO STUDIES

2 x 10(5) B16 murine melanoma cells were incubated with aluminum phthalocyanine (AlpcS4, 2.5 mg/kg) and were then subjected to photoradiation (50, 100 or 200 J/cm2). Viability was then assessed. In vivo studies:

HISTOLOGY

C57/B1 mice received 2 x 10(5) B16 cells subcutaneously and were randomized into study (PDT) and three control groups. AlpcS4 2.5 mg/kg was injected intraperitoneally and the mice were exposed to light (100 J/cm2). After 24 hours they were sacrificed and underwent autopsies. Survival: 40 mice were randomized into PDT (40 J/cm2) and control groups and were monitored for 50 days. Tumor growth: 40 mice were randomized into one control and three treatment groups (PDT on day 3, 6, or 12 after injection with B16 cells), and were monitored for 50 days. Temperature: Tumor temperatures before and at the end of PDT were recorded.

RESULTS

IN VITRO STUDIES

PDT caused a decrease in cell viability to 15.5 +/- 0.7%, 11.5 +/- 2.1%, and 1.5 +/- 0.7% (at 50, 100, and 200 J/cm2, respectively; P < .001). A significant reduction in thymidine incorporation was noted at all energy levels. In vivo studies:

HISTOLOGY

PDT caused massive tumor necrosis. Survival: PDT prolonged the survival of mice (41 +/- 13.4 days) compared to controls (15.8 +/- 3.8 days, P < .001). Tumor growth: 31 days after injection with B16 cells, the tumor size was 2.6 +/- 0.3 cm in the control group and 1.6 +/- 0.2, 0.9 +/- 0.3, and 1.0 +/- 0.4 cm in the PDT groups (days 3, 6 and 12, respectively; P < .01). Temperature: PDT increased skin temperature to 42.8 degrees C +/- 1.3 degrees C, 45.3 degrees C +/- 3.5 degrees C, and 51.7 degrees C +/- 2.7 degrees C at 40, 60, and 100 J/cm2, respectively (P < .01).

CONCLUSIONS

Photodynamic therapy was found to have significant effects in experimental melanoma in mice. The role of PDT in human melanoma remains to be studied.

5-Aminolevulinic acid-based photodynamic therapy. Clinical research and future challenges

BACKGROUND

Photodynamic therapy (PDT) for cancer patients has developed into an important new clinical treatment modality in the past 25-years. PDT involves administration of a tumor-localizing photosensitizer or photosensitizer prodrug (5-aminolevulinic acid [ALA], a precursor in the heme biosynthetic pathway) and the subsequent activation of the photosensitizer by light. Although several photosensitizers other than ALA-derived protoprophyrin IX (PpIX) have been used in clinical PDT, ALA-based PDT has been the most active area of clinical PDT research during the past 5 years. Studies have shown that a higher accumulation of ALA-derived PpIX in rapidly proliferating cells may provide a biologic rationale for clinical use of ALA-based PDT and diagnosis. However, no review updating the clinical data has appeared so far.

METHODS

A review of recently published data on clinical ALA-based PDT and diagnosis was conducted.

RESULTS

Several individual studies in which patients with primary nonmelanoma cutaneous tumors received topical ALA-based PDT have reported promising results, including outstanding cosmetic results. However, the modality with present protocols does not in general, appear to be superior to conventional therapies with respect to initial complete response rates and long term recurrence rates, particularly in the treatment of nodular skin tumors. Topical ALA-PDT does have the following advantages over conventional treatments: it is noninvasive; it produces excellent cosmetic results; it is well tolerated by patients; it can be used to treat multiple superficial lesions in short treatment sessions; it can be applied to patients who refuse surgery or have pacemakers and bleeding tendency; it can be used to treat lesions in specific locations, such as the oral mucosa or the genital area; it can be used as a palliative treatment; and it can be applied repeatedly without cumulative toxicity. Topical ALA-PDT also has potential as a treatment for nonneoplastic skin diseases. Systemic administration of ALA does not seem to be severely toxic, but the advantage of using this approach for PDT of superficial lesions of internal hollow organs is still uncertain. The ALA-derived porphyrin fluorescence technique would be useful in the diagnosis of superficial lesions of internal hollow organs.

CONCLUSIONS

Promising results of ALA-based clinical PDT and diagnosis have been obtained. The modality has advantages over conventional treatments. However, some improvements need to be made, such as optimization of parameters of ALA-based PDT and diagnosis; increased tumor selectivity of ALA-derived PpIX; better understanding of light distribution in tissue: improvement of light dosimetry procedure; and development of simpler, cheaper, and more efficient light delivery systems.

Clinical applications of photodynamic therapy

This is a review of photodynamic therapy, which is a classic binary system involving the use of a photosensitizer and light of very specific wavelength, consistent with the absorption characteristics of that sensitizer. As a binary system, its effects are almost entirely limited to tumour cells, but the major drawback is its limited penetration because it utilizes physical light within the visible spectrum. For Photofrin II, which is the only approved sensitizer for clinical use in this country, the effects are limited to approximately 0.5 cm or less, depending on the tissue and the amount of blood, etc. Newer sensitizers offer more penetration and the opportunity to repeat treatments, because the newer sensitizers do not have the very long (up to 10 weeks) period of enhanced skin sensitivity to sunlight. A summary of the results of photodynamic therapy by individual sites is included. The use of newer sensitizers, which represent much purer substances than Photofrin II, should give an opportunity for repeated treatments, which should eventually make this form of treatment far more important than it has been up to now.

Photodynamic therapy for the treatment of squamous cell carcinoma using benzoporphyrin derivative

BACKGROUND

Photodynamic therapy (PDT) involves laser light excitation of a tumor-localizing photosensitizer to destroy neoplasms. Benzoporphyrin derivative (BPD) is a new photosensitizer with several favorable characteristics.

OBJECTIVE

Studies were designed to: 1) assess the efficacy of BPD-mediated PDT in treating in vivo squamous cell carcinomas (SCC); 2) obtain dosimetry data for BPD and laser parameters; and 3) establish clinical and histologic correlates of BPD-induced tumor regression.

METHODS

Human SCC was implanted into nude mice. One group received BPD followed by laser light of 150 J/cm2 from an argon-pumped dye laser at 690 nm. Three control groups included laser energy alone, BPD alone, and no treatment.

RESULTS

At day 21 posttreatment only PDT-treated tumors showed a statistically significant decrease in tumor volume and complete cure rate. Clinical resolution (scar) correlated perfectly with histologic resolution (scar).

CONCLUSION

Human SCC in a nude mouse model responds to BPD-mediated PDT.

Superficial photodynamic therapy with topical 5-aminolaevulinic acid for superficial primary and secondary skin cancer

Between January 1991 and December 1992 a phase I trial of superficial photodynamic therapy (PDT) using topical application of 5-aminolaevulinic acid (ALA) was undertaken to treat Bowen's disease, superficial basal cell carcinomas (BCCs) and metastatic skin secondaries from breast (adenocarcinoma) or pinna (squamous cell carcinoma). Promising results were obtained with 36 areas of Bowen's disease, with a complete response rate of 89% at a median follow-up of 18 months. The treatment of BCCs was less successful, with 50% complete responses in 16 lesions at a median follow-up of 17 months. Metastatic nodules responded poorly. The treatment was well tolerated and discomfort during light irradiation could be reduced by prior application of 'Emla' cream. Lesions wept for 1-2 weeks following treatment and healed over a period of approximately 2 months. For large areas of Bowen's disease, particularly in anatomically difficult areas and in elderly patients, PDT using ALA may constitute a single simple alternative outpatient treatment to existing therapies. Further work is required to improve the results with BCCs.

Photodynamic therapy for early squamous cell cancer of the upper aerodigestive tract

Photodynamic therapy (PDT) is a treatment modality that results in selective destruction of malignant cells by combining a photosensitizing agent (hematoporphyrin derivative), which is taken up by the cells, and a laser light. This therapeutic modality has been effectively used in managing cancers of the skin, bronchi and bladder. In the head and neck area, however, its use has been confined to the palliation of advanced lesions which have proved refractory to conventional therapy. While this is unquestionably a valid role, its true value, therapeutically, may be in the management of early cancers arising in the upper aerodigestive tract. At the University of Cincinnati, PDT has been used on a variety of such early cancers where, for a variety of reasons, conventional therapy was not possible. A preliminary experience with this modality in managing lesions of the larynx, oral cavity and oropharynx has demonstrated that this is a viable alternative.

The nude mouse xenograft system: a model for photodetection and photodynamic therapy in head and neck squamous cell carcinoma

Mechanisms for hematoporphyrin derivative (HPD) localization in malignant tissue and in photodynamic therapy (PDT) have not been established. The authors' experience with human cancer xenografts in nude mice as a tumor system for the experimental study of these mechanisms is described. Human mucosal head and neck squamous cell carcinoma was successfully transplanted to nude mice in 29 per cent of trials and serially passed through multiple generations in three tumor lines. Time required for progressive growth averaged 13.9 days, and 300 mm3 tumors were obtained in four weeks. Take rates per passage varied, in part because of infection, and exponential growth rates varied among the three lines. However, within a single line exponential growth rates were similar. Average growth constants for the period of exponential growth were 0.14, 0.13, and 0.09 for the three lines. Fluorescent microscopy of excised xenografts revealed HPD fluorescence principally in connective tissue cells. Minimal fluorescence was seen in malignant epithelial cells. Spectrophotometric measures of HPD uptake in homogenized tissue showed highest values in liver. Tumor HPD levels were higher than those for either skin or muscle. The authors conclude that this tumor system can be used effectively to study HPD and PDT in head and neck cancer.

Photodynamic therapy of gynecologic neoplasms after presensitization with hematoporphyrin derivative

Five patients with various gynecologic neoplasms were treated with photodynamic therapy using 630-nm light delivered from an argon dye laser system following the intravenous injection of hematoporphyrin derivative (HpD). A patient with multifocal squamous cell cancer of the vagina had no evidence of disease 15 months after her first photodynamic therapy treatment. Autopsy nine months after the first treatment of another patient with multifocal invasive cancer of the vagina and parametrium showed no evidence of tumor on the surface of the vagina. Eight months after treatment of an 8 X 12 cm area of Bowen's disease of the vulva and thigh, there was no evidence of disease. Vaginal bleeding from breast cancer metastatic to the endometrium was controlled by one treatment until the patient expired five months later from her disease. Adenocarcinoma metastatic to the vaginal cuff showed partial response when vaginectomy was performed five weeks after photodynamic therapy.