Selective immmunotherapy through extracorporeal photochemotherapy: yesterday, today, and tomorrow

X-Ray Psoralen Activated Cancer Therapy (X-PACT)

This work investigates X-PACT (X-ray Psoralen Activated Cancer Therapy): a new approach for the treatment of solid cancer. X-PACT utilizes psoralen, a potent anti-cancer therapeutic with current application to proliferative disease and extracorporeal photopheresis (ECP) of cutaneous T Cell Lymphoma. An immunogenic role for light-activated psoralen has been reported, contributing to long-term clinical responses. Psoralen therapies have to-date been limited to superficial or extracorporeal scenarios due to the requirement for psoralen activation by UVA light, which has limited penetration in tissue. X-PACT solves this challenge by activating psoralen with UV light emitted from novel non-tethered phosphors (co-incubated with psoralen) that absorb x-rays and re-radiate (phosphoresce) at UV wavelengths. The efficacy of X-PACT was evaluated in both in-vitro and in-vivo settings. In-vitro studies utilized breast (4T1), glioma (CT2A) and sarcoma (KP-B) cell lines. Cells were exposed to X-PACT treatments where the concentrations of drug (psoralen and phosphor) and radiation parameters (energy, dose, and dose rate) were varied. Efficacy was evaluated primarily using flow cell cytometry in combination with complimentary assays, and the in-vivo mouse study. In an in-vitro study, we show that X-PACT induces significant tumor cell apoptosis and cytotoxicity, unlike psoralen or phosphor alone (p<0.0001). We also show that apoptosis increases as doses of phosphor, psoralen, or radiation increase. Finally, in an in-vivo pilot study of BALBc mice with syngeneic 4T1 tumors, we show that the rate of tumor growth is slower with X-PACT than with saline or AMT + X-ray (p<0.0001). Overall these studies demonstrate a potential therapeutic effect for X-PACT, and provide a foundation and rationale for future studies. In summary, X-PACT represents a novel treatment approach in which well-tolerated low doses of x-ray radiation are delivered to a specific tumor site to generate UVA light which in-turn unleashes both short- and potentially long-term antitumor activity of photo-active therapeutics like psoralen.

Characterization of the DNA copy-number genome in the blood of cutaneous T-cell lymphoma patients

Cutaneous T-cell lymphoma (CTCL) is a heterogeneous non-Hodgkin's lymphoma that may variably involve the skin, lymph nodes, and peripheral blood. Malignant burden ranges from cutaneous patches and plaques with little evidence of blood involvement to erythroderma often in association with frank leukemia, as in Sézary syndrome. Toward a better understanding of the pathogenesis of this CD4+ T-cell malignancy, we conducted a high-resolution genomic analysis combining DNA (23 samples) and mRNA (12 samples) data of peripheral blood isolates from CTCL patients across a spectrum of stages. Strikingly, even patients with limited involvement, e.g., normal CD4 counts, contained significant copy-number alterations. Defining genomic characteristics of CTCL blood involvement included gains on 8q and 17q, and deletions on 17p and chromosome 10. A consensus analysis of 108 leukemic CTCL samples demonstrated global similarities among patients with varied blood involvement, narrowing 38 of 62 loci. Toward an annotated framework for in vitro testing, we also characterized genomic alterations in five CTCL cell lines (HH, HUT78, PNO, SeAx, and Sez4), revealing intact core features of leukemic CTCL. Together, these studies produce the most comprehensive view of the leukemic CTCL genome to date, with implications for pathogenesis, molecular classification, and potential future therapeutic developments.

Experimental extracorporeal photopheresis therapy significantly delays the development of diabetes in non-obese diabetic mice

In our previous studies, we demonstrated that infusion of apoptotic cells significantly prevented type 1 diabetes (T1D) in non-obese diabetic (NOD) mice. Extracorporeal photopheresis (ECP) is an apoptotic cell-based therapy used clinically for immune-mediated disorders. In this study, we examined the effect that intravenous delivery of apoptotic cells (ECP-treated) has in the prevention of T1D in NOD mice. We discovered that five weekly injections of ECP-treated NOD spleen cells, beginning at 8 weeks of age, significantly delayed diabetes onset. Furthermore, cell dose studies demonstrated that low dose ECP-treated spleen cells (2x10(5) cells/injection/mouse) had similar protective effects as compared to high dose (5x10(6) cells/injection). In contrast to ECP-treated cells alone, ECP-treated cells combined with beta cell antigens appeared to improve the protective effect as shown by the marked reduction in insulitis in the islets. Delivery of ECP-treated spleen cells or ECP-treated spleen cells plus beta cell antigen increased Foxp3(+) Tregs, and beta cell antigen-specific T cell proliferation was significantly suppressed in vivo in these two groups. In addition, we found that ECP-treated cells did not induce global immunosuppression or autoimmunity against nuclear antigens. In conclusion, ECP-treated cells provide a safe and effective approach in T1D prevention, suggesting that clinical ECP has great potential for managing human T1D.

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.

Management of refractory early-stage cutaneous T-cell lymphoma

Cutaneous T-cell lymphoma (CTCL) is a heterogeneous group of non-Hodgkin's lymphomas that manifest primarily in the skin. Mycosis fungoides is recognized as the most common type of CTCL. Patients with early-stage CTCL usually have a benign and chronic disease course. However, although there is a wide array of therapeutic options for early-stage CTCL, not all patients respond to these individual therapies, resulting in refractory cutaneous disease over time. Refractory early-stage CTCL poses an important therapeutic challenge, as one of the principal treatment goals is to keep the disease confined to the skin, thereby preventing disease progression. Much of the focus of current research has been on the evaluation of already available skin-directed therapies and biologic response modifiers and combination regimens thereof, such as the combination of psoralen and UVA (PUVA) with interferon-alpha or retinoids. Recent novel developments include oral bexarotene, a retinoid X receptor-selective retinoid that has activity in all stages of CTCL and has been shown to be effective in patients with refractory early-stage disease as well as advanced-stage disease. Likewise, the topical gel formulation of bexarotene has proved to be an important therapeutic option in patients with refractory or relapsed lesions. Oral bexarotene and topical bexarotene have been approved by the US FDA for the treatment of refractory CTCL. Systemic chemotherapy is typically reserved for advanced-stage CTCL and is usually not recommended for early-stage, skin-limited disease. However, recent exploratory studies indicate that low-dose methotrexate may represent an overall well tolerated therapy in a subset of patients with refractory early-stage CTCL, as may pegylated liposomal doxorubicin, which is currently being investigated in this specific clinical setting. Another recently FDA-approved therapy is the interleukin-2 fusion toxin denileukin diftitox, which is now well established to play a role in the treatment of refractory CTCL, including early-stage extensive plaque disease. The value of other agents, such as topical tazarotene, topical methotrexate, and topical imiquimod, and of novel immunomodulatory approaches including monoclonal antibodies, still needs to be assessed for refractory early-stage CTCL.

Mycosis fungoides and the Sézary syndrome

PURPOSE OF REVIEW

Mycosis fungoides and the Sézary syndrome represent a heterogeneous group of good-to-intermediate-risk non-Hodgkin lymphomas that have recently been identified as distinct histopathologic and clinical entities by the World Health Organization and European Organization for Research on the Treatment of Cancer lymphoma classification systems. Significant progress has been made in identifying and categorizing patients based on clinical prognostic factors, but there is little information regarding the etiology, molecular biology, and molecular genetics of these diseases. This review outlines recent advances in clinical diagnosis and prognosis as well as novel therapeutic approaches.

RECENT FINDINGS

A number of reports have further defined clinical prognostic subgroups among early-stage patients and those with circulating Sézary cells. The recent availability and demonstrated efficacy of the oral RXR retinoid, bexarotene, has altered the treatment paradigm of early-stage patients who would not otherwise be exposed to systemic therapies. Novel targeted agents and receptor-directed therapies, including the fusion toxin, denileukin diftitox, histone deacetylase inhibitors, and novel nucleoside analog therapies, have demonstrated promising activity and are undergoing further clinical evaluation. The evolution of immunotherapy has been augmented by studies demonstrating the efficacy of peptide-loaded dendritic cells as well as the use of photopheresis to generate an anti-idiotype cytotoxic T-cell response.

SUMMARY

This review will enumerate the most recent findings with respect to clinical staging, prognosis, and treatment of patients with mycosis fungoides and the Sézary syndrome. Novel treatment options will be reviewed and treatment paradigms will be outlined.