Extracorporeal photopheresis--a new approach for the treatment of cutaneous T cell lymphomas

A deep dive into UV-based phototherapy: Mechanisms of action and emerging molecular targets in inflammation and cancer

UV-based phototherapy (including psoralen plus UVA (PUVA), UVB and UVA1) has a long, successful history in the management of numerous cutaneous disorders. Photoresponsive diseases are etiologically diverse, but most involve disturbances in local (and occasionally systemic) inflammatory cells and/or abnormalities in keratinocytes that trigger inflammation. UV-based phototherapy works by regulating the inflammatory component and inducing apoptosis of pathogenic cells. This results in a fascinating and complex network of simultaneous events-immediate transcriptional changes in keratinocytes, immune cells, and pigment cells; the emergence of apoptotic bodies; and the trafficking of antigen-presenting cells in skin-that quickly transform the microenvironment of UV-exposed skin. Molecular elements in this system of UV recognition and response include chromophores, metabolic byproducts, innate immune receptors, neurotransmitters and mediators such as chemokines and cytokines, antimicrobial peptides, and platelet activating factor (PAF) and PAF-like molecules that simultaneously shape the immunomodulatory effects of UV and their interplay with the microbiota of the skin and beyond. Phototherapy's key effects-proapoptotic, immunomodulatory, antipruritic, antifibrotic, propigmentary, and pro-prebiotic-promote clinical improvement in various skin diseases such as psoriasis, atopic dermatitis (AD), graft-versus-host disease (GvHD), vitiligo, scleroderma, and cutaneous T-cell lymphoma (CTCL) as well as prevention of polymorphic light eruption (PLE). As understanding of phototherapy improves, new therapies (UV- and non-UV-based) are being developed that will modify regulatory T-cells (Treg), interact with (resident) memory T-cells and /or utilize agonists and antagonists as well as antibodies targeting soluble molecules such as cytokines and chemokines, transcription factors, and a variety of membrane-associated receptors.

Review of extracorporeal photopheresis in early-stage (IA, IB, and IIA) cutaneous T-cell lymphoma

BACKGROUND

Extracorporeal photopheresis (ECP) has been used for nearly 20 years for the treatment of cutaneous T-cell lymphoma (CTCL). A substantial body of literature reports that this form of photoimmunotherapy improves or stabilizes the course of disease in a subset of patients across all stages. However, current clinical approach usually reserves ECP for patients who do not respond to other treatments or for patients with late-stage disease or Sézary syndrome (SS).

METHODS

A comprehensive Pubmed/Medline literature search was performed to identify studies reporting the use and efficacy of ECP in early stage (IA, IB, and IIA) CTCL. Information regarding prognostic factors and survival of early-stage patients treated with ECP was also obtained and summarized.

RESULTS

The heterogenous nature of the reports and lack of any prospective randomized trials made evaluation of response to treatment difficult. However, the current literature contains at least 124 early-stage patients treated with ECP or ECP plus adjuvant therapy from 1987-2007 in 16 different reports. Response rates of treatment for this patient population with ECP and ECP plus adjuvant therapy varied from 33-88%.

CONCLUSIONS

Given the very low side effect profile of ECP compared with other therapies and its demonstrated efficacy, this treatment modality is possibly beneficial for patients with earlier stages of CTCL. Randomized prospective studies are needed to establish the role of ECP in this disease subset.

[Standard and experimental therapy of cutaneous T-cell lymphoma]

Cutaneous T-cell lymphoma represent a heterogeneous group of diseases characterized by skin invasion of monoclonal T-lymphocytes. These cutaneous T-cell lymphomas are divided into 3 groups based on clinical, histological and immunohistological characteristics: Indolent with a survival time of over 10 years, aggressive with a survival time less than 10 years and provisional (EORTC classification). Standard treatments such as PUVA, total skin electron beam, methotrexate, polychemotherapy regimens, retinoids and photopheresis have been used for years. Bexarotene is a newly registered drug. To achieve better response rates, several new drugs are being evaluated in clinical trails, including imiquimod, denileukon-diftitox, liposomal doxorubicin, adeno-interferon-gamma and various combination approaches.

A sensitive gas chromatography-mass spectrometry assay reveals increased levels of monohydroxyeicosatetraenoic acid isomers in human plasma after extracorporeal photoimmunotherapy and under in vitro ultraviolet A exposure

Extracorporeal photoimmunotherapy (photopheresis) is a highly effective therapy in the treatment of various disorders. Although extracorporeal photoimmunotherapy has been successfully used for more than 10 y, its mechanism of action is still unclear. The formation of reactive oxygen species have been implicated in extracorporeal photoimmunotherapy, but malonyl dialdehyde as a marker of systemic lipid peroxidation did not increase significantly during treatment. To investigate further the involvement of reactive oxygen species in extracorporeal photoimmunotherapy, we have introduced a highly sensitive negative ion gas chromatography-mass spectrometry based method for quantitating oxygenated arachidonic acid isomers (hydroxyeicosatetraenoic acids) in plasma samples of patients treated with extracorporeal photoimmunotherapy. In the plasma of healthy volunteers pmole amounts of 2-, 3-, 5-, 8-12-, and 15-hydroxyeicosatetraenoic acid were detected and we observed a dose-dependent augmentation in these metabolites when the blood was irradiated with increasing doses of ultraviolet A in the presence of the photosensitizer 8-methoxypsoralen. Analysis of plasma samples obtained from patients before and after extracorporeal photoimmunotherapy revealed a characteristic increase in total hydroxyeicosatetraenoic acid levels, particularly of 5-hydroxyeicosatetraenoic acid which contributed 80% to the sum of all hydroxyeicosatetraenoic acid isomers. Chiral phase high-performance liquid chromatography indicated almost equal amounts of 5S- and 5R-hydroxyeicosatetraenoic acid suggesting that the majority of lipid peroxidation products are formed via nonenzymatic oxidation reactions.