The role of the EP receptors for prostaglandin E2 in skin and skin cancer

One of the most common features of exposure of skin to ultraviolet (UV) light is the induction of inflammation, a contributor to tumorigenesis, which is characterized by the synthesis of cytokines, growth factors and arachidonic acid metabolites, including the prostaglandins (PGs). Studies on the role of the PGs in non-melanoma skin cancer (NMSC) have shown that the cyclooxygenase-2 (COX-2) isoform of the cyclooxygenases is responsible for the majority of the pathological effects of PGE2. In mouse skin models, COX-2 deficiency significantly protects against chemical carcinogen- or UV-induced NMSC while overexpression confers endogenous tumor promoting activity. Current studies are focused on identifying which of the G protein-coupled EP receptors mediate the tumor promotion/progression activities of PGE2 and the signaling pathways involved. As reviewed here, the EP1, EP2, and EP4 receptors, but not the EP3 receptor, contribute to NMSC development, albeit through different signaling pathways and with somewhat different outcomes. The signaling pathways activated by the specific EP receptors are context specific and likely depend on the level of PGE2 synthesis, the differential levels of expression of the different EP receptors, as well as the levels of expression of other interacting receptors. Understanding the role and mechanisms of action of the EP receptors potentially offers new targets for the prevention or therapy of NMSCs

Dose study of the multikinase inhibitor, LY2457546, in patients with relapsed acute myeloid leukemia to assess safety, pharmacokinetics, and pharmacodynamics

Volker Wacheck1, Michael Lahn2, Gemma Dickinson3, Wolfgang Füreder4, Renata Meyer4, Susanne Herndlhofer4, Thorsten Füreder1, Georg Dorfner5, Sada Pillay2, Valérie André6, Timothy P Burkholder7, Jacqueline K Akunda8, Leann Flye-Blakemore9, Dirk Van Bockstaele9, Richard F Schlenk10, Wolfgang R Sperr4, Peter Valent4,111Department of Clinical Pharmacology, Medical University of Vienna, Währinger Gürtel, Vienna, Austria; 2Early Oncology Clinical Investigation, Eli Lilly and Company, Indianapolis, IN, USA; 3Department of Pharmacokinetics, Eli Lilly and Company, Erl Wood Research Centre, Windlesham, Surrey, UK; 4Department of Internal Medicine I, Division of Hematology and Hemostaseology, Medical University of Vienna, Währinger Gürtel, Vienna, Austria; 5Eli Lilly GesmbH, Medical Department, Vienna, Austria; 6Department of Statistics, Eli Lilly and Company, Erl Wood Research Centre, Surrey, UK; 7Discovery Chemistry Research and Technology, Eli Lilly and Company, Indianapolis, IN, USA; 8Nonclinical Toxicology, Eli Lilly and Company, Indianapolis, IN, USA; 9Flow Cytometry and Cell Analysis, Esoterix Clinical Trials Services, Mechelen, Belgium; 10Universitätsklinikum Ulm, Klinik für Innere Medizin III, Ulm, Germany; 11Ludwig Boltzmann Cluster Oncology, Vienna, AustriaBackground: Acute myeloid leukemia (AML) is a life-threatening malignancy with limited treatment options in chemotherapy-refractory patients. A first-in-human dose study was designed to investigate a safe and biologically effective dose range for LY2457546, a novel multikinase inhibitor, in patients with relapsed AML.Methods: In this nonrandomized, open-label, dose escalation Phase I study, LY2457546 was administered orally once a day. Safety, pharmacokinetics, changes in phosphorylation of target kinases in AML blasts, and risk of drug–drug interactions (DDI) were assessed.Results: Five patients were treated at the starting and predicted minimal biologically effective dose of 50 mg/day. The most commonly observed adverse events were febrile neutropenia, epistaxis, petechiae, and headache. The majority of adverse events (81%) were Grade 1 or 2. One patient had generalized muscle weakness (Grade 3), which was deemed to be a dose-limiting toxicity. Notably, the pharmacokinetic profile of LY2457546 showed virtually no elimination of LY2457546 within 24 hours, and thus prevented further dose escalation. No significant DDI were observed. Ex vivo flow cytometry studies showed downregulation of the phosphoproteins, pcKIT, pFLT3, and pS6, in AML blasts after LY2457546 administration. No medically relevant responses were observed in the five treated patients.Conclusion: No biologically effective dose could be established for LY2457546 in chemotherapy-resistant AML patients. Lack of drug clearance prevented safe dose escalation, and the study was terminated early. Future efforts should be made to develop derivatives with a more favorable pharmacokinetic profile.Keywords: multikinase inhibitor, pharmacokinetics, safety, acute myeloid leukemia, pharmacodynamics&nbsp

Cell death in the skin

The skin is the largest organ of the body and protects the organism against external physical, chemical and biological insults, such as wounding, ultraviolet radiation and micro-organisms. The epidermis is the upper part of the skin that is continuously renewed. The keratinocytes are the major cell type in the epidermis and undergo a specialized form of programmed cell death, called cornification, which is different from classical apoptosis. In keep with this view, several lines of evidence indicate that NF-kB is an important factor providing protection against keratinocyte apoptosis in homeostatic and inflammatory conditions. In contrast, the hair follicle is an epidermal appendage that shows cyclic apoptosis-driven involution, as part of the normal hair cycle. The different cell death programs need to be well orchestrated to maintain skin homeostasis. One of the major environmental insults to the skin is UVB radiation, causing the occurrence of apoptotic sunburn cells. Deregulation of cell death mechanisms in the skin can lead to diseases such as cancer, necrolysis and graft-versus-host disease. Here we review the apoptotic and the anti-apoptotic mechanisms in skin homeostasis and disease