Treatment of Malignant Melanoma by High-Peak-Power 1064 nm Irradiation Followed by Photodynamic Therapy

Impact of near-infrared radiation in dermatology

Sunlight that reaches the human skin contains solar energy composed of 6.8% ultraviolet (UV), 38.9% visible light and 54.3% infrared radiation. In addition to natural near-infrared (NIR), human skin is increasingly exposed to artificial NIR from medical devices and electrical appliances. Thus, we are exposed to tremendous amounts of NIR. Many studies have proven the effects of UV exposure on human skin and skin cancers but have not investigated well the effects of NIR exposure. Furthermore, many of the previous NIR studies have used NIR resources without a water filter or a contact cooling. With these resources, a substantial amount of NIR energy is absorbed in the superficial layers and only limited NIR energy can be delivered to deeper tissues. Thus, they could not sufficiently evaluate the effects of incident solar NIR. In order to simulate solar NIR that reaches the skin, a water filter is essential because solar NIR is filtered by atmospheric water. In reality, NIR increases the surface temperature and induces thermal effects so a contact cooling is needed to pursue the properties of NIR. I clarify that NIR can penetrate the skin and non-thermally affect the subcutaneous tissues, including muscle and bone marrow, using a NIR resource with a water filter and a cooling system. I would like to emphasize the biological effects of NIR which have both merits and demerits. Appropriate NIR irradiation induces dermal heating thermally and non-thermally induces collagen and elastin stimulation, which results in skin tightening. NIR also induces non-thermal DNA damage of mitotic cells, which may have the potential application for treating cancer. However, as continuous NIR exposure may induce photoaging and potentially photocarcinogenesis, we should consider the effect of, not only UV, but also NIR and the necessity for protection against solar NIR. Here, this paper introduces the new aspects of the biological effects of NIR radiation.

Photodynamic therapy against achromic M6 melanocytes: phototoxicity of lipophilic axially substituted aluminum phthalocyanines and hexadecahalogenated zinc phthalocyanines

Lipophilic and axially substituted tri-n-hexylsiloxy aluminum phthalocyanine and cholesteryloxy diphenylsiloxy aluminum phthalocyanine were synthesized and assayed in PDT against M6 melanocytes. In the conditions used (λ > 480 nm , 10 mW cm-2, egg-yolk lecithin or cremophor EL formulation) they both exhibited a higher photodynamic effect than chloroaluminum phthalocyanine. They displayed 2% to 3.5% cell viability at 10-5M dose for 20 min irradiation. Hexadecafluoro zinc phthalocyanine was synthesized to increase the lipophilicity of zinc phthalocyanine, hexadecachloro zinc phthalocyanine was also included because it would theoretically enhance the phototoxicity. In all the delivery systems used, their photodynamic effect against M6 melanocytes was lower in comparison with zinc phthalocyanine and axially substituted aluminum phthalocyanines. A 2 h irradiation treatment with 3 × 10-6 M hexadecafluoro zinc phthalocyanine and 10-5 M hexadecachloro zinc phthalocyanine led to 60% and 15% cell viability respectively. In all cases, the cell killing effect was light-and dose-dependent and was higher in cremophor EL micelles than in the egg-yolk lecithin formulation.

Non-thermal cytocidal effect of infrared irradiation on cultured cancer cells using specialized device

As infrared penetrates the skin, thermal effects of infrared irradiation on cancer cells have been investigated in the field of hyperthermia. We evaluated non-thermal effects of infrared irradiation using a specialized device (1100-18000 nm with filtering of wavelengths between 1400 and 1500 nm and contact cooling) on cancer cells. In in vitro study, five kinds of cultured cancer cell lines (MCF7 breast cancer, HeLa uterine cervical cancer, NUGC-4 gastric cancer, B16F0 melanoma, and MDA-MB435 melanoma) were irradiated using the infrared device, and then the cell proliferation activity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. Proliferation of all the cancer cell lines was significantly suppressed by infrared irradiation. Total infrared output appeared to be correlated with cell survival. Increased temperature during infrared irradiation appeared not to play a role in cell survival. The maximum temperature elevation in the wells after each shot in the 20 and 40 J/cm(2) culture was 3.8 degrees C and 6.9 degrees C, respectively. In addition, we have shown that infrared irradiation significantly inhibited the tumor growth of MCF7 breast cancer transplanted in severe combined immunodeficiency mice and MDA-MB435 melanoma transplanted in nude mice in vivo. Significant differences between control and irradiated groups were observed in tumor volume and frequencies of TUNEL-positive and Ki-67-positive cells. These results indicate that infrared, independent of thermal energy, can induce cell killing of cancer cells. As this infrared irradiation schedule reduces discomfort and side effects, reaches the deep subcutaneous tissues, and facilitates repeated irradiations, it may have potential as an application for treating various forms of cancer.

5-aminolaevulinic acid photodynamic therapy in a transgenic mouse model of skin melanoma

Photodynamic therapy (PDT) is widely used to treat preneoplastic skin lesions and non-melanoma skin tumours. Studies analyzing the effects of PDT on malignant melanoma have yielded conflicting results. On the one hand, melanoma cell lines in culture as well as cell lines transplanted into experimental animals were sensitive to PDT. On the other hand, spontaneous melanomas of human patients responded poorly to most PDT regimens tested so far. Here, we analyzed effects of 5-aminolaevulinic acid (5-ALA)-based PDT on melanoma cell lines and on experimental melanomas. To mimic the clinical situation as closely as possible, metallothionein-I/ret (MT-ret) mice, a transgenic model of skin melanoma development, were used. Optimal doses of 5-ALA as well as energy doses and power densities were determined in vitro using a cell line (Mel25) established by us from a melanoma of an MT-ret transgenic mouse as well as commercially available human and mouse melanoma cell lines. Treatment with light irradiation alone had no effect. In combination with 5-ALA, however, this illumination readily induced the death of all mouse and human melanoma cell lines examined. Still, 5-ALA PDT caused only minor focal regressive changes including haemorrhages and fibrosis of MT-ret melanomas in vivo and did not significantly delay tumour growth. These results show that, even though MT-ret melanoma cells are vulnerable to 5-ALA PDT in vitro, malignant MT-ret melanomas in vivo are quite resistant to this type of therapy at doses which are highly effective in vitro.

Photothermal sensitisation as a novel therapeutic approach for tumours: studies at the cellular and animal level

Irradiation of B78H1 murine amelanotic melanoma cells with 850 nm light emitted from a Ti:sapphire laser, operated in a pulsed mode at high fluence rates and in the presence of Ni(II)-octabutoxy-naphthalocyanine (NiNc), promoted a photothermally sensitised process leading to fast and irreversible cell death. This resulted in the ejection of a consistent mass of cytoplasmic material from the irradiated cells that was detected by scanning electron microscopy. The extensive chemical and mechanical damage was probably caused by the photoinduced generation of an acoustic shock wave. The efficiency of the photoprocess was modulated by intracellular concentration of NiNc and maximally by the formation of aggregated naphthalocyanine clusters in specific subcellular areas. Very similar results were obtained upon irradiation of NiNc-loaded C32 human amelanotic melanoma cells and transformed murine HT-1080 and HaCaT fibroblasts. From these results, photothermal sensitisation appears to be a general phenomenon and preliminary studies with mice bearing subcutaneously transplanted amelanotic melanomas, irradiated with 850 nm light 24 h after intravenous injection of NiNc, suggest that this approach has potential for the therapy of some types of skin tumours.

Treatment of murine cutaneous melanoma with near infrared light

Treatment of cutaneous melanoma (M-3 and B16-F10 implanted in mice) with rapidly-scanned, tightly-focused near infrared light elicits selective destruction of tumor tissue. A single laser treatment yielded complete eradication in >90% of B16-F10 tumors with thicknesses of approximately 3 mm; amelanotic M-3 tumors proved less responsive (ca 25% clearance rate). In addition to local tumor destruction, laser treatment of B16-F10 tumors in immunocompetent mice stimulated enhanced cytokine levels (interleukin-2 and interleukin-10) within treated tumor tissues and rejection of tumor cells upon a subsequent challenge dose. Such an antitumor immune response may lead to improved outcomes at both the treatment site and at sites of distant metastasis.

Topical 5-aminolaevulinic acid photodynamic therapy for the treatment of skin conditions other than non-melanoma skin cancer

Topical 5-aminolaevulinic acid (ALA) photodynamic therapy (PDT) is used increasingly for superficial non-melanoma skin cancer (NMSC) and dysplasia. However, the relative accumulation of the photosensitizer protoporphyrin IX (PpIX) in diseased tissue is not specific for neoplastic disease, and has been shown after the application of ALA to benign proliferative skin conditions such as viral warts and psoriasis. This review appraises the quality of evidence available for the use of topical ALA-PDT in the treatment of skin conditions other than NMSC. The diseases that have been studied in most detail are recalcitrant viral warts, acne, psoriasis and cutaneous T-cell lymphoma. Publications relating to the treatment of other diseases by topical PDT are restricted to small case series or case reports. The relevant literature will be discussed and the potential for topical PDT in the treatment of several skin diseases is highlighted, although more detailed studies are required to clarify the role of PDT beyond the treatment of NMSC.

Phototriggering of liposomal drug delivery systems

Over the past several years, photodynamic therapy (PDT) has been approved for the treatment of various cancers. Additional applications of photochemical processes for triggering site-specific drug delivery are in early stages of development at this time. This review focuses on the literature appearing between January 1996-June 2001 that describe new and ongoing studies of phototriggering mechanisms that may ultimately find utility in drug delivery applications.

Postirradiation hyperthermia selectively potentiates the merocyanine 540-sensitized photoinactivation of small cell lung cancer cells

Lung cancer has long been considered a disease that might benefit from the dose escalation of radio/chemotherapy afforded by a stem cell transplant. However, the clinical experience with high-dose chemotherapy and autologous bone marrow transplantation in lung cancer has been disappointing, with most trials showing little or no improvement in long-term survival. Unfortunately, lung cancer has a tendency to metastasize to the bone marrow, and lung cancer cells are known to circulate in the peripheral blood. Therefore, there is concern that autologous stem cell grafts from lung cancer patients may reinoculate recipients with live tumor cells. Photochemical purging of stem cell grafts with Merocyanine 540 (MC540) is highly effective against a wide range of leukemia and lymphoma cells and is well tolerated by normal hematopoietic stem and progenitor cells. Most solid tumor cells (including lung cancer cells), however, are only moderately sensitive or refractory to MC540-mediated photodynamic therapy (PDT). We report here that postirradiation hyperthermia (< or = 42 degrees C, 3 h) potentiates the MC540-mediated photoinactivation of both wild-type (H69) and cisplatin-resistant mutant (H69/CDDP) small cell lung cancer cells by several orders of magnitude, while only minimally enhancing the depletion of normal human granulocyte/macrophage progenitor cells. Our data suggest that postirradiation hyperthermia provides a simple and effective means of extending the utility of MC540-PDT to the purging of stem cell grafts contaminated with lung cancer and possibly other solid tumor cells.

High efficiency of benzoporphyrin derivative in the photodynamic therapy of pigmented malignant melanoma

Benzoporphyrin derivative monoacid ring A (verteporfin, BPD-MA) when intravenously injected (5.5 micromol kg(-1)) to C57/BL6 mice bearing a subcutaneously transplanted B1 melanoma gave a maximal accumulation in the tumour within 1-3 h with recoveries of 1.84-1.96 micromol kg(-1). Irradiation of BPD-MA-loaded melanoma with 690-nm light from a dye laser at 3 h and 9 h post injection induced tumour necrosis and delay of tumour growth of 28 and 14 days respectively. The response of the tumour to BPD-MA photosensitization was enhanced by pretreatment with 1064-nm light from a pulse-operated Nd:YAG laser, which caused a selective breakdown of melanosomes.