History of UV Lamps, Types, and Their Applications.

The use of ultraviolet (UV) light, for the treatment of skin conditions, dates back to the early 1900s. It is well known that sunlight can be of therapeutic value, but it can also lead to deleterious effects such as burning and carcinogenesis. Extensive research has expanded our understanding of UV radiation and its effects in human systems and has led to the development of man-made UV sources that are more precise, safer, and more effective for the treatment of wide variety of dermatologic conditions.

A Retrospective 30 Years After Discovery of the Enhanced Permeability and Retention Effect of Solid Tumors: Next-Generation Chemotherapeutics and Photodynamic Therapy--Problems, Solutions, and Prospects.

Solid tumor has unique vascular architecture, excessive production of vascular mediators, and extravasation of macromolecules from blood vessels into the tumor tissue interstitium. These features comprise the phenomenon named the EPR effect of solid tumors, described in 1986. Our investigations on the EPR revealed that many mediators, such as bradykinin, NO, and prostaglandins, are involved in the EPR effect, which is now believed to be the most important element for cancer-selective drug delivery. However, tumors in vivo manifest great diversity, and some demonstrate a poor EPR effect, for example, because of impaired vascular flow involving thrombosis, with poor drug delivery and therapeutic failure. Another important element of this effect is that it operates in metastatic cancers. Because few drugs are currently effective against metastases, the EPR effect offers a great advantage in nanomedicine therapy. The EPR effect can also be augmented two to three times via nitroglycerin, ACE inhibitors, and angiotensin II-induced hypertension. The delivery of nanomedicines to tumors can thereby be enhanced. In traditional PDT, most PSs had low MW and little tumor-selective accumulation. Our hydroxypropylmetacrylamide-polymer-conjugated-PS, zinc protoporphyrin (apparent MW >50 kDa) showed tumor-selective accumulation, as revealed by fluorescent imaging of autochthonous cancers. After one i.v. injection of polymeric PS followed by two or three xenon light irradiation/treatments, most tumors regressed. Thus, nanoprobes with the EPR effect seem to have remarkable effects. Enhancing the EPR effect by using vascular modulators will aid innovations in PDT for greater tumor-targeted drug delivery.

More Adventures in Photodynamic Therapy.

Photodynamic therapy is a procedure that can provide a selective eradication of neoplastic disease if sufficient drug, light, and oxygen are available. As this description suggests, it involves the photosensitization of malignant tissues to irradiation with photons in the visible range. While not suitable for tumors at unknown loci, it can be of use for eradication of cancer at surgical margins and therapy at sites where substantial surgery might otherwise be involved. Drug development has been delayed by several factors including the reluctance of major pharmaceutical firms in the United States to invest in this technology along with some unwise approaches in the past.

History of phototherapy in dermatology.

Over many centuries, treatment with sunlight or "heliotherapy" was used in the treatment of skin diseases. More than 3500 years ago, ancient Egyptian and Indian healers used the ingestion of plant extracts or seeds in addition to sunlight for treating "leucoderma". Modern phototherapy began with Nobel Prize winner Niels Finsen who developed a "chemical rays" lamp with which he treated patients with skin tuberculosis. However, it took several decades until phototherapy was introduced anew into the dermatological armamentarium. It was the development of photochemotherapy (PUVA) in 1974 that marked the beginning of a huge upsurge in photodermatology. The subsequent development of high intensity UV sources with defined spectra facilitated an optimized therapy for psoriasis and led to an expansion of indications for photo(chemo)therapy also in combination with topical and systemic agents. The introduction of extracorporeal photopheresis in 1987 for cutaneous T-cell lymphoma and of topical photodynamic therapy widely expanded the therapeutic possibilities in dermato-oncology.

Indocyanine green angiography-guided photodynamic therapy for treatment of chronic central serous chorioretinopathy: a pilot study. 2003.

BACKGROUND: Most patients with central serous chorioretinopathy (CSC) have spontaneous resolution of exudative macular detachments and a good visual prognosis. Patients with CSC have a primary choroidal hyperpermeability problem evident as multifocal areas of hyperpermeability during indocyanine green (ICG) angiography. A small percentage of patients develop chronic or progressive disease with widespread decompensation of the retinal pigment epithelium and severe vision loss. There is no known treatment for this variant of the disorder. PURPOSE: To study ICG-guided photodynamic therapy (PDT) with verteporfin as a potential treatment for patients with chronic CSC. METHODS: Twenty eyes of 15 patients were studied with fluorescein angiography, optical coherence tomography, and ICG angiography to diagnose the maculopathy, monitor the detachments, and localize the choroidal hyperpermeability of the disorder. PDT with ICG guidance was applied to areas of choroidal hyperpermeability, and the patients were observed to determine the anatomic and functional outcomes. RESULTS: Photodynamic therapy guided by ICG was associated with complete resolution of exudative macular detachments in 12 patients and incomplete resolution in the remaining eight eyes. The vision improved in six eyes and remained unchanged in 14 eyes during a mean follow-up of 6.8 months. Six weeks after treatment, the mean visual acuity improved by 0.55 lines, an amount that was marginally significant. There was a significant inverse correlation between the baseline visual acuity and the amount of improvement in acuity at 6 weeks. No patient had any treatment-related side effects. CONCLUSIONS: Indocyanine green angiography-guided PDT with verteporfin seems to aid in the resolution of exudative detachments in patients with chronic CSC. This treatment was associated with a rapid reduction in subretinal fluid and improvement in visual acuity. Although the follow-up time and number of patients in this pilot study were limited, the encouraging results and lack of complications suggest that further study is indicated.

Treatment of polypoidal choroidal vasculopathy with photodynamic therapy. 2002.

PURPOSE: To study the effects of photodynamic therapy using verteporfin in the treatment of patients with subfoveal polypoidal choroidal vasculopathy (PCV). METHODS: A retrospective chart review of 16 consecutive patients with subfoveal PCV treated with photodynamic therapy using verteporfin was performed. RESULTS: The mean age of the patients involved was 70.5 years. The mean follow-up time was 12 months. The visual acuity improved in 9 (56.3 %), remained the same in 5 (31.3 %), and decreased in 2 (12.5 %). The mean change in visual acuity was an improvement of 2.38 lines, a difference that was highly significant (P = 0.004). The change in visual acuity was negatively correlated with increasing age. The final visual acuity was positively correlated with initial acuity and negatively correlated with age. These results were confirmed by multiple linear regression. No patient had any lasting complication from the treatment. CONCLUSIONS: Subfoveal PCV has no proven method of treatment. Although the follow-up time and the number of patients in this pilot study were limited, the encouraging results and lack of complications suggest that further study is indicated.

Forging Forward in Photodynamic Therapy.

In 1978, a Cancer Research article by Dougherty and colleagues reported the first large-scale clinical trial of photodynamic therapy (PDT) for treatment of 113 cutaneous or subcutaneous lesions associated with ten different kinds of malignancies. In classic applications, PDT depends on excitation of a tissue-localized photosensitizer with wavelengths of visible light to damage malignant or otherwise diseased tissues. Thus, in this landmark article, photosensitizer (hematoporphyrin derivative) dose, drug-light interval, and fractionation scheme were evaluated for their therapeutic efficacy and normal tissue damage. From their observations came early evidence of the mechanisms of PDT's antitumor action, and in the decades since this work, our knowledge of these mechanisms has grown to build an understanding of the multifaceted nature of PDT. These facets are comprised of multiple cell death pathways, together with antivascular and immune stimulatory actions that constitute a PDT reaction. Mechanism-informed PDT protocols support the contribution of PDT to multimodality treatment approaches. Moreover, guided by an understanding of its mechanisms, PDT can be applied to clinical needs in fields beyond oncology. Undoubtedly, there still remains more to learn; new modes of cell death continue to be elucidated with relevance to PDT, and factors that drive PDT innate and adaptive immune responses are not yet fully understood. As research continues to forge a path forward for PDT in the clinic, direction is provided by anchoring new applications in mechanistically grounded protocol design, as was first exemplified in the landmark work conducted by Dougherty and colleagues. See related article by Dougherty and colleagues, Cancer Res 1978;38:2628-35.

DNA damage, repair and the improvement of cancer therapy - A tribute to the life and research of Barbara Tudek.

Professor Barbara Tudek received the Frits Sobels Award in 2019 from the European Environmental Mutagenesis and Genomics Society (EEMGS). This article presents her outstanding character and most important lines of research. The focus of her studies covered alkylative and oxidative damage to DNA bases, in particular mutagenic and carcinogenic properties of purines with an open imidazole ring and 8-oxo-7,8-dihydroguanine (8-oxoGua). They also included analysis of mutagenic properties and pathways for the repair of DNA adducts of lipid peroxidation (LPO) products arising in large quantities during inflammation. Professor Tudek did all of this in the hope of deciphering the mechanisms of DNA damage removal, in particular by the base excision repair (BER) pathway. Some lines of research aimed at discovering factors that can modulate the activity of DNA damage repair in hope to enhance existing anti-cancer therapies. The group's ongoing research aims at deciphering the resistance mechanisms of cancer cell lines acquired following prolonged exposure to photodynamic therapy (PDT) and the possibility of re-sensitizing cells to PDT in order to increase the application of this minimally invasive therapeutic method.

Biophysical aspects of photodynamic therapy.

Over the last three decades photodynamic therapy (PDT) has been developed to a useful clinical tool, a viable alternative in the treatment of cancer and other diseases. Several disciplines have contributed to this development: chemistry in the development of new photosensitizing agents, biology in the elucidation of cellular processes involved in PDT, pharmacology and physiology in identifying the mechanisms of distribution of photosensitizers in an organism, and, last but not least, physics in the development of better light sources, dosimetric concepts and construction of imaging devices, optical sensors and spectroscopic methods for determining sensitizer concentrations in different tissues. Physics and biophysics have also helped to focus on the role of pH for sensitizer accumulation, dose rate effects, oxygen depletion, temperature, and optical penetration of light of different wavelengths into various types of tissue. These are all important parameters for optimally effective PDT. The present review will give a brief, physically based, overview of PDT and then discuss some of the main biophysical aspects of this therapeutic modality.

Photodynamic therapy of cerebral glioma--a review Part I--a biological basis.

Photodynamic therapy (PDT) has been investigated extensively in the laboratory for decades, and for over 25 years in the clinical environment, establishing it as a useful adjuvant to standard treatments for many cancers. A combination of both photochemical and photobiological processes occur that lead to the eventual selective destruction of the tumour cells. It is a potentially valuable adjuvant therapy that can be used in conjunction with other conventional therapies for the treatment of cerebral glioma. PDT has undergone extensive laboratory studies and clinical trials with a variety of photosensitizers (PS) and tumour models of cerebral glioma. Many environmental and genetically based factors influence the outcome of the PDT response. The biological basis of PDT is discussed with reference to laboratory and preclinical studies.

PDT: What's Past Is Prologue.

Despite descriptions of light-mediated therapy in ancient texts and the discovery of photodynamic therapy (PDT) in the early 1900s, the landmark article in 1978 in Cancer Research by Dougherty and his colleagues at the Roswell Park Cancer Institute remains rightly viewed as the starting point for clinical PDT in modern medicine. As a large clinical series that explored many of the factors now viewed as critical determinates of PDT dose, efficacy, and toxicity, that study showed remarkable foresight, yet it also served to raise as many questions as it answered. Since its publication, PDT has been increasingly utilized in clinical practice for the treatment of both benign and malignant conditions, and many of their questions have yielded new technologies and areas of investigation, thus remaining highly relevant nearly 40 years after their initial asking. Moreover, continuing advances in our ability to measure physical properties such as absorbed light dose, photosensitizer concentration, tissue oxygen concentration, and singlet oxygen production in real-time may allow for adaptive modification of light delivery during PDT on a fine scale to optimize treatment response. Finally, combining molecularly targeted drugs and novel photosensitizers has the potential to improve further the therapeutic index and extend the spectrum of clinical PDT far beyond what was imagined when that sentinel manuscript was written. Cancer Res; 76(9); 2497-9. ©2016 AACRSee related article by Dougherty et al., Cancer Res 1978;38:2628-35Visit the Cancer Research 75(th) Anniversary timeline.

Oral methoxsalen photochemotherapy for the treatment of psoriasis: a cooperative clinical trial. 1977.

Extensive psoriasis in 1,308 patients has been treated two or three times a week with oral 8-methoxypsoralen followed by high intensity, long-wave ultraviolet light (PUVA). Excluding 169 patients still under early treatment, psoriasis cleared in 88% and failed to clear in 3%. One percent dropped out due to complications of treatment, and 8% for other reasons. The twice-a-week schedule was superior for patients with lighter skin types. Once a remission was induced, there was no difference in its maintenance when patients were treated once a week, once every other week, or once every third week. Each of these schedules was superior to no maintenance treatment. Immediate side effects of the 45,000 treatments administered in the first 18 months of this study were uncommon, temporary, and generally mild. No clinically significant changes in laboratory screening or eye examinations attributable to PUVA have been uncovered.

Psoralen photobiology and photochemotherapy: 50 years of science and medicine.

In 1998 it is appropriate to commemorate the 50th anniversary of el Mofty's use of purified 8-methoxypsoralen (8-MOP) in the treatment of vitiligo (el Mofty AM. A preliminary clinical report on the treatment of leukoderma with Ammi majus linn. J R Egypt Med Assn 1948,31:651 65. el Mofty AM, el Sawalhy H, el Mofty M. Clinical study of a new preparation of 8-methoxypsoralen in photochemotherapy. Int J Dermatol 1994;8:588 92). Two young American dermatologists (Aaron Lerner and Thomas Fitzpatrick) were intrigued by the potency of this material. After Lerner determined that artificial long wavelength ultraviolet (320-400 nm, UVA) radiation was the most efficient for activating 8-MOP. the development of artificial sources enabled the efficient delivery of these photons to skin containing 8-MOP. Their initial studies for vitiligo led to further development of this therapy for the treatment of psoriasis (Parrish JA, Fitzpatrick TB, Tannenbaum L, et al. Photochemotherapy of psoriasis with oral methoxsalen and long-wave ultraviolet light. New Engl J Med 1974;291:1207-11. Honigsmann H, Fitzpatrick TB, Pathak MA, et al. Oral photochemotherapy with psoralen and UVA (PUVA): principles and practice. In: Fitzpatrick TB, Eisen AZ, Wolf K, editors. Dermatology in General Medicine. New York: McGraw-Hill, 1987:1728-54). This photochemotherapy came to be called 'PUVA' (psoralen + UVA). The position PUVA holds today as one of the most common procedures performed in dermatology can be traced to their initial curiosity and their subsequent ingenuity. Further developments in more recent years capitalized on their seminal work. The therapy met with unprecedented success from the outset, leaving little perceived need to understand underlying science. However, in recent years there has been a new found interest in the basic aspects of psoralen photobiology and molecular mechanistic events contributing to therapeutic responses as well as to the development of skin cancers in PUVA patients. These will be surveyed in this review commemorating the 50 years of modern psoralen photobiology and photomedicine.

Photodynamic therapy of age-related macular degeneration: History and principles.

We briefly review the history and principles of photodynamic therapy (PDT), especially as it is applied to choroidal neovascularization (CNV) in age-related macular degeneration (AMD). After a brief general history of PDT, we discuss the relationship between the physicochemical structure and photodynamic activity of the second-generation photosensitizers, such as those in current clinical use. We then discuss the basic photophysics of photosensitizer molecules, and describe the initial chemical reactions induced by activated sensitizers. We outline a novel method for screening photosensitizers to be used in treating CNV, as well as the complex biomolecular pathways modulated by PDT-induced oxidative stress and the vascular effects of PDT in solid tumors. The paper closes with a discussion of how all this information might be used to improve the selectivity and efficacy of clinically useful photosensitizers.

The Goeckerman treatment in psoriasis: six decades of experience at the Mayo Clinic.

The Goeckerman treatment for severe psoriasis has been used at the Mayo Clinic for six decades in a closely supervised hospital setting. It is an effective and safe method of treatment and is still the standard with which new forms of treatment must be compared.

Twenty years of experience with PDD and PDT in Poland--review.

This article is a review of laboratory and clinical research undertaken in Poland in PDD and PDT over the past 20 years. These are divided into two parallel research areas. The first is based on clinical trials where new modalities of photosensitizer synthesis, molecular mechanisms of PDT and other aspects are investigated. The second is concerned with clinical aspects of PDD and PDT in both pre-neoplastic and malignant disease. In Poland there were 2 National Congresses in 2006 and 2008 with 100 and 400 participants respectively. One of the oldest centers of Photodynamic Diagnostics and Therapy is located in Bytom. For about 10 years it has led clinical research in Poland with PDD and PDT in such medical disciplines as dermatology, gastroenterology, laryngology, pulmonology, gynecology, and orthopedics.