Discovery of an Oral, Rule of 5 Compliant, Interleukin 17A Protein-Protein Interaction Modulator for the Potential Treatment of Psoriasis and Other Inflammatory Diseases.

Interleukin 17A (IL-17A) is an interleukin cytokine whose dysregulation is implicated in autoimmune disorders such as psoriasis, and monoclonal antibodies against the IL-17A pathway are now well-established and very effective treatments. This article outlines the work that led to the identification of 23 as an oral, small-molecule protein-protein interaction modulator (PPIm) clinical development candidate. Protein crystallography provided knowledge of the key binding interactions between small-molecule ligands and the IL-17A dimer, and this helped in the multiparameter optimization toward identifying an orally bioavailable, Rule of 5 compliant PPIm of IL-17A. Overlap of early ligands led to a series of benzhydrylglycine-containing compounds that allowed the identification of dimethylpyrazole as a key substituent that gave PPIm with oral bioavailability. Exploration of the amino acid portion of the structure then led to dicyclopropylalanine as a group that gave potent and metabolically stable compounds, including the development candidate 23.

Characterization of a novel non-steroidal glucocorticoid receptor agonist optimized for topical treatment.

Glucocorticoids (GCs) are commonly used topical treatments for skin diseases but are associated with both local and systemic side effects. In this study, we describe a selective non-steroidal glucocorticoid receptor (GR) agonist for topical use, LEO 134310, which is rapidly deactivated in the blood resulting in low systemic exposure and a higher therapeutic index in the TPA-induced skin inflammation mouse model compared with betamethasone valerate (BMV) and clobetasol propionate (CP). Selectivity of LEO 134310 for GR was confirmed within a panel of nuclear receptors, including the mineralocorticoid receptor (MR), which has been associated with induction of skin atrophy. Topical treatment with LEO 134310 in minipigs did not result in any significant reduction in epidermal thickness in contrast to significant epidermal thinning induced by treatment with BMV and CP. Thus, the profile of LEO 134310 may potentially provide an effective and safer treatment option for skin diseases compared with currently used glucocorticoids.

Macrolide Inspired Macrocycles as Modulators of the IL-17A/IL-17RA Interaction.

Interleukin 17 (IL-17) cytokines promote inflammatory pathophysiology in many autoimmune diseases, including psoriasis, multiple sclerosis, rheumatoid arthritis, and inflammatory bowel disease. Such broad involvement of IL-17 in various autoimmune diseases makes it an ideal target for drug discovery. Psoriasis is a chronic inflammatory disease characterized by numerous defective components of the immune system. Significantly higher levels of IL-17A have been noticed in lesions of psoriatic patients, if compared to non-lesion parts. Therefore, this paper is focused on the macrolide inspired macrocycles as potential IL-17A/IL-17RA modulators and covers the molecular design, synthesis, and in vitro profiling. Macrocycles are designed to diversify and enrich chemical space through different ring sizes and a variety of three-dimensional shapes. Inhibitors in the nM range were identified in both target-based and phenotypic assays. In vitro ADME as well as in vivo PK properties are reported.

Topical 'dual-soft' glucocorticoid receptor agonist for dermatology.

Steroidal glucocorticoids (GR agonists) have been widely used for the topical treatment of skin disorders, including atopic dermatitis. They are a very effective therapy, but they are associated with both unwanted local effects in the skin (skin thinning/atrophy) and systemic side effects. These effects can limit the long-term utility of potent steroids. Here we report on a topically delivered non-steroidal GR agonist, that has the potential to deliver high efficacy in the skin, but due to rapid metabolism in the blood & liver ("dual-soft") it should have greater systemic safety than existing treatments. In addition, compared to less selective steroidal GR agonists, the new non-steroidal Selective Glucocorticoid Agonists (SEGRAs) have the potential to avoid the skin atrophy observed with existing topical steroids. Due to its potential for reduced skin atrophy and low systemic exposure, LEO 134310 (17) may be suitable for long term topical treatment of skin diseases such as atopic dermatitis and psoriasis.

Ingenol Disoxate: A Novel 4-Isoxazolecarboxylate Ester of Ingenol with Improved Properties for Treatment of Actinic Keratosis and Other Non-Melanoma Skin Cancers.

INTRODUCTION: Ingenol mebutate gel (Picato®, LEO Pharma A/S) is approved for the field treatment of actinic keratosis and is characterized by high sustained clearance of actinic lesions. The inherent propensity of ingenol mebutate towards chemical rearrangement necessitates refrigeration of the final product. We sought to identify novel ingenol derivatives with enhanced chemical stability and similar or improved in vitro potency and in vivo efficacy. METHODS: A number of ingenol esters were synthesized with full regiocontrol from ingenol. Chemical stability was determined in aqueous buffer at physiological pH and hydroalcoholic gel at lower pH. Acute cytotoxicity was determined in HeLa or HSC-5 cells. Keratinocyte proliferation, viability and caspase 3/7 activation was measured in primary epidermal keratinocytes. Relative gene expression levels were determined by real-time quantitative PCR. Evaluation of in vivo tumor ablating potential was performed in the murine B16 melanoma mouse model and in the UV-induced skin carcinogenesis model in hairless SKH-1 mice following topical treatment for two consecutive days with test compounds formulated at 0.1% in a hydroalcoholic gel. RESULTS: This work resulted in the identification of ingenol disoxate (LEO 43204) displaying increased stability in a clinically relevant formulation and in aqueous buffer with minimal pH-dependent acyl migration degradation. Ingenol disoxate exhibited a significantly higher cytotoxic potency relative to ingenol mebutate. Likewise, cell growth arrest in normal human keratinocyte was more potently induced by ingenol disoxate, which was accompanied by protein kinase C dependent transcription of markers of keratinocyte differentiation. Most notably, ingenol disoxate possessed a superior antitumor effect in a B16 mouse melanoma model and significantly increased median survival time relative to ingenol mebutate. A significant effect on tumor ablation was also observed in a murine model of ultraviolet irradiation-induced skin carcinogenesis. CONCLUSION: These data illustrate that the favorable in vitro and in vivo pharmacological properties driving ingenol mebutate efficacy are either preserved or improved in ingenol disoxate. In combination with improved chemical stability to potentially facilitate storage of the final product at ambient temperatures, these features support further development of ingenol disoxate as a convenient and efficacious treatment modality of non-melanoma skin cancers. FUNDING: LEO Pharma A/S.

Phosphodiesterases in the rat ovary: effect of cAMP in primordial follicles.

Phosphodiesterases (PDEs) are important regulators of the intracellular cAMP concentration, which is a central second messenger that affects a multitude of intracellular functions. In the ovaries, cAMP exerts diverse functions, including regulation of ovulation and it has been suggested that augmented cAMP levels stimulate primordial follicle growth. The present study examined the gene expression, enzyme activity and immunolocalization of the different cAMP hydrolysing PDEs families in the rat ovary. Further, the effect of PDE4 inhibition on primordial follicle activation in cultured neonatal rat ovaries was also evaluated. We found varied expression of all eight families in the ovary with Pde7b and Pde8a having the highest expression each accounting for more than 20% of the total PDE mRNA. PDE4 accounted for 15-26% of the total PDE activity. Immunoreactive PDE11A was found in the oocytes and PDE2A in the corpora lutea. Incubating neonatal rat ovaries with PDE4 inhibitors did not increase primordial follicle activation or change the expression of the developing follicle markers Gdf9, Amh, Inha, the proliferation marker Mki67 or the primordial follicle marker Tmeff2. In addition, the cAMP analogue 8-bromo-cAMP did not increase AKT1 or FOXO3A phosphorylation associated with follicle activation or increase the expression of Kitlg known to be associated with follicle differentiation but did increase the Tmeff2, Mki67 and Inha expression in a dose-dependent manner. In conclusion, this study shows that both Pde7b and Pde8a are highly expressed in the rodent ovary and that PDE4 inhibition does not cause an increase in primordial follicle activation.

Synthesis, biological evaluation and SAR of 3-benzoates of ingenol for treatment of actinic keratosis and non-melanoma skin cancer.

Ingenol 3-benzoates were investigated with respect to chemical stability, pro-inflammatory effects, cell death induction and PKCδ activation. A correlation between structure, chemical stability and biological activity was found and compared to ingenol mebutate (ingenol 3-angelate) used for field treatment of actinic keratosis. We also provided further support for involvement of PKCδ for induction of oxidative burst and cytokine release. Molecular modeling and dynamics calculations corroborated the essential interactions between key compounds and C1 domain of PKCδ.

Syntheses, biological evaluation and SAR of ingenol mebutate analogues for treatment of actinic keratosis and non-melanoma skin cancer.

Ingenol mebutate is the active ingredient in Picato® a new drug for the treatment of actinic keratosis. A number of derivatives related to ingenol mebutate were prepared by chemical synthesis from ingenol with the purpose of investigating the SAR and potency in assays relating to pro-inflammatory effects (induction of PMN oxidative burst and keratinocyte cytokine release), the potential of cell death induction, as well as the chemical stability. By modifications of the ingenol scaffold several prerequisites for activity were identified. The chemical stability of the compounds could be linked to an acyl migration mechanism. We were able to find analogues of ingenol mebutate with comparable in vitro properties. Some key features for potent and more stable ingenol derivatives have been identified.

Ingenol mebutate: induced cell death patterns in normal and cancer epithelial cells.

We investigated the proposed necrotic mechanism of ingenol mebutate, a natural compound with anti-cancer properties in human keratinocytes, the human squamous cell carcinoma cell line HSC-5, and HeLa cervix carcinoma cells. Topical application of a clinical dose of ingenol mebutate 0.05% (1.15 mM) gel to human reconstituted full-thickness skin equivalents strongly reduced epidermal, but not dermal viability. Ingenol mebutate showed cytotoxic potency between 200-300 M on normal and cancer cells. When keratinocytes were induced to differentiate, they became significantly less sensitive to ingenol mebutate and half-maximal induction of cell death required more than 300 M ingenol mebutate. Cytotoxic concentrations of ingenol mebutate caused rupture of the mitochondrial network within minutes paralleled by cytosolic calcium release in all cells. Subsequently, plasma membrane integrity was lost as seen by propidium uptake into the cells. This was in sharp contrast to lysis of cells with low concentrations of the detergent Triton X-100 that permeabilized the plasma membrane within minutes without affecting organelle morphology. Buffering of intracellular calcium and inhibition of the mitochondrial permeability transition pore reduced the cytotoxic effect of ingenol mebutate in cancer cells, but not in normal keratinocytes. However, these inhibitors could not prevent cell death subsequent to prolonged incubation. Our findings reveal that ingenol mebutate does not mediate cytotoxicity by a simple lytic, necrotic mechanism, but activates distinct processes involving multiple cell organelles in a cell-type and differentiation-dependent manner. These data improve our understanding of ingenol mebutate-target cell interactions and offer new insights relevant to the removal of aberrant cells in human skin.

Strontium is a biased agonist of the calcium-sensing receptor in rat medullary thyroid carcinoma 6-23 cells.

The calcium-sensing receptor (CaSR)-specific allosteric modulator cinacalcet has revolutionized the treatment of secondary hyperparathyroidism in patients with chronic kidney disease. However, its application is limited to patients with end-stage renal disease because of hypocalcemic side effects presumably caused by CaSR-mediated calcitonin secretion from thyroid parafollicular C-cells. These hypocalcemic side effects might be dampened by compounds that bias the signaling of CaSR, causing similar therapeutic effects as cinacalcet without stimulating calcitonin secretion. Because biased signaling of CaSR is poorly understood, the objective of the present study was to investigate biased signaling of CaSR by using rat medullary thyroid carcinoma 6-23 cells as a model of thyroid parafollicular C-cells. By doing concentration-response experiments we focused on the ability of two well known CaSR agonists, calcium and strontium, to activate six different signaling entities: G(q/11) signaling, G(i/o) signaling, G(s) signaling, extracellular signal-regulated kinases 1 and 2 (ERK1/2) signaling, intracellular calcium ([Ca(2+)](i)) mobilization, and calcitonin secretion. The experiments showed that strontium biases CaSR signaling toward ERK1/2 signaling and possibly another pathway independent of G(q/11) signaling and [Ca(2+)](i) mobilization. It is noteworthy that the potency of strontium-stimulated calcitonin secretion was elevated compared with calcium. Combining these results with experiments investigating signaling pathway components involved in calcitonin secretion, we found that the enhanced potency of strontium-mediated calcitonin secretion was caused by a different signaling pattern than that produced by calcium. Together, our results suggest that calcitonin secretion can be affected by CaSR-stimulated signaling bias, which may be used to develop novel drugs for the treatment of secondary hyperparathyroidism.

ZP2307, a novel, cyclic PTH(1-17) analog that augments bone mass in ovariectomized rats.

Daily injections of human parathyroid hormone (1-34), hPTH(1-34), provide a highly effective treatment option for severe osteoporosis. However, PTH analogs shorter than 28 amino acids do not retain any bone augmenting potential. Here, we present ZP2307 ([Ac5c¹, Aib³, Leu8, Gln¹°, Har¹¹, Ala¹², Trp¹4, Asp¹7]PTH(1-17)-NH2), a novel, chemically modified and cyclized hPTH(1-17) analog, that augments bone mass in ovariectomized, osteopenic rats. Subcutaneous administration of this structurally constrained, K¹³-D¹7 side-chain-to-side-chain cyclized peptide reversed bone loss and increased bone mineral density (BMD) up to or above baseline levels in rat long bones and vertebrae. Highly significant effects of ZP2307 were achieved at doses of 40-320 nmol/kg. Micro-CT and histomorphometric analyses showed that ZP2307 improved quantitative and qualitative parameters of bone structure. Biomechanical testing of rat femora confirmed that ZP2307 dramatically increased bone strength. Over a broad maximally effective dose range (40-160 nmol/kg) ZP2307 did not increase serum concentrations of ionized free calcium above normal levels. Only at the highest dose (320 nmol/kg) ZP2307 induced hypercalcemic calcium levels in the ovariectomized rats. To our knowledge ZP2307 is the smallest PTH peptide analog known to exert augmentation of bone. Our findings suggest that ZP2307 has the potential to effectively augment bone mass over a broad dose range without a concomitant increase in the serum concentration of ionized free calcium above the normal range.

Amylin(1-8) is devoid of anabolic activity in bone.

Amylin(1-8), a cyclic peptide consisting of the eight N-terminal amino acids of the 37-amino acid peptide amylin, has been shown to induce proliferation of primary osteoblasts and to induce bone formation in healthy male mice, whereas no data on efficacy in bone disease-related models have been reported. Therefore, we evaluated any effects of amylin(1-8) in ovariectomized rats with established osteopenia, a model for postmenopausal osteoporosis. At doses up to 100 nmol/kg/day, a dose highly effective in healthy mice, amylin(1-8) was unable to increase bone mineral density in ovariectomized rats during an 8-week treatment period. Histomorphometric analysis of the tibia indicated that amylin(1-8) did not change bone histomorphometric parameters. In an attempt to verify any potential biological effects of amylin(1-8), we investigated the efficacy of this peptide in various in vitro assays. Experiments designed to confirm previously published results on the proliferative effects of amylin(1-8) on primary osteoblasts failed to show any response. Amylin(1-8) was able to partially displace (125)I-rat amylin(1-37) from amylin receptors composed of the calcitonin receptor and RAMP1, indicating specific interaction of the peptide with the amylin binding site. However, in vitro efficacy assays with amylin(1-8) in calcitonin receptor-RAMP-positive HEK293T and MCF7 cells failed to reveal any agonist activity of amylin(1-8), whereas amylin(1-37) showed the expected agonist activity. In conclusion, our results indicate that amylin(1-8) does not show agonist activity on amylin receptors, does not affect osteoblast proliferation, and is devoid of anabolic activity in bone.

Increasing gap junctional coupling: a tool for dissecting the role of gap junctions.

Much of our current knowledge about the physiological and pathophysiological role of gap junctions is based on experiments where coupling has been reduced by either chemical agents or genetic modification. This has brought evidence that gap junctions are important in many physiological processes. In a number of cases, gap junctions have been implicated in the initiation and progress of disease, and experimental uncoupling has been used to investigate the exact role of coupling. The inverse approach, i.e., to increase coupling, has become possible in recent years and represents a new way of testing the role of gap junctions. The aim of this review is to summarize the current knowledge obtained with agents that selectively increase gap junctional intercellular coupling. Two approaches will be reviewed: increasing coupling by the use of antiarrhythmic peptide and its synthetic analogs and by interfering with the gating of gap junctional channels.

Identification of ischemia-regulated phosphorylation sites in connexin43: A possible target for the antiarrhythmic peptide analogue rotigaptide (ZP123).

Previous studies suggest that dephosphorylation of connexin43 (Cx43) is related to uncoupling of gap junction communication, which plays an important role in the genesis of ischemia-induced ventricular tachycardia. We studied changes in Cx43 phosphorylation during global ischemia in the absence and presence of the antiarrhythmic peptide analogue rotigaptide (formerly known as ZP123). Phosphorylation analysis was performed on Cx43 purified from isolated perfused rat hearts using matrix-assisted laser desorption/ionization mass spectrometry and liquid chromatography electrospray ionization tandem mass spectrometry. Thirteen different serine phosphorylation sites were identified in Cx43 during non-ischemic conditions, three of which had not previously been described. Within the first 7 min of ischemia, Ser306 became fully dephosphorylated whereas Ser330 became phosphorylated. Between 15 and 30 min of ischemia, the critical time interval where gap junction uncoupling occurs, Ser297 and Ser368 also became fully dephosphorylated. During the same time period, all untreated hearts developed asystole. Treatment with rotigaptide significantly increased the time to ischemia-induced asystole and suppressed dephosphorylation of Ser297 and Ser368 at 30 min of ischemia. Our results suggest that phosphorylation of Ser297 and Ser368 may be involved in functional gating of Cx43 during ischemia and may be possible downstream targets for rotigaptide signaling.

The antiarrhythmic peptide rotigaptide (ZP123) increases connexin 43 protein expression in neonatal rat ventricular cardiomyocytes.

Rotigaptide (formerly ZP123) is a novel antiarrhythmic peptide that prevents uncoupling of connexin 43 (Cx43)-mediated, gap junction communication during acute metabolic stress. Since rotigaptide's long-term effects on Cx43 are unknown, we studied its effect on Cx43 protein levels at 24 h in neonatal ventricular myocytes. As determined by Western blot analysis, rotigaptide produced a dose-dependent increase in Cx43 protein expression that reached a maximum level at 100 nM. Furthermore, 100 nM rotigaptide markedly increased Cx43 immunoreactivity and Cx43-positive gap junctions as observed in immunocytochemical studies. Cycloheximide, an inhibitor of protein synthesis, was used to investigate rotigaptide's mechanism of action. Cycloheximide (10 microg/ml) reduced Cx43 protein levels to 39% of vehicle (17 mM ethanol) whereas cotreatment of 10 microg/ml cycloheximide with 100 nM rotigaptide reduced Cx43 protein levels to 56% of vehicle. Our findings suggest that rotigaptide's effect on Cx43 expression is partly due to increased biosynthesis.

The chloride channel inhibitor NS3736 [corrected] prevents bone resorption in ovariectomized rats without changing bone formation.

UNLABELLED: Chloride channel activity is essential for osteoclast function. Consequently, inhibition of the osteoclastic chloride channel should prevent bone resorption. Accordingly, we tested a chloride channel inhibitor on bone turnover and found that it inhibits bone resorption without affecting bone formation. This study indicates that chloride channel inhibitors are highly promising for treatment of osteoporosis. INTRODUCTION: The chloride channel inhibitor, NS3736, blocked osteoclastic acidification and resorption in vitro with an IC50 value of 30 microM. When tested in the rat ovariectomy model for osteoporosis, daily treatment with 30 mg/kg orally protected bone strength and BMD by approximately 50% 6 weeks after surgery. Most interestingly, bone formation assessed by osteocalcin, mineral apposition rate, and mineralized surface index was not inhibited. MATERIALS AND METHODS: Analysis of chloride channels in human osteoclasts revealed that ClC-7 and CLIC1 were highly expressed. Furthermore, by electrophysiology, we detected a volume-activated anion channel on human osteoclasts. Screening 50 different human tissues showed a broad expression for CLIC1 and a restricted immunoreactivity for ClC-7, appearing mainly in osteoclasts, ovaries, appendix, and Purkinje cells. This highly selective distribution predicts that inhibition of ClC-7 should specifically target osteoclasts in vivo. We suggest that NS3736 is inhibiting ClC-7, leading to a bone-specific effect in vivo. RESULTS AND CONCLUSION: In conclusion, we show for the first time that chloride channel inhibitors can be used for prevention of ovariectomy-induced bone loss without impeding bone formation. We speculate that the coupling of bone resorption to bone formation is linked to the acidification of the resorption lacunae, thereby enabling compounds that directly interfere with this process to be able to positive uncouple this process resulting in a net bone gain.

Caveolae are highly immobile plasma membrane microdomains, which are not involved in constitutive endocytic trafficking.

To investigate whether caveolae are involved in constitutive endocytic trafficking, we expressed N- and C- terminally green fluorescent protein (GFP)-tagged caveolin- 1 fusion proteins in HeLa, A431, and Madin-Darby canine kidney cells. The fusion proteins were shown by immunogold labeling to be sorted correctly to caveolae. By using confocal microscopy and photobleaching techniques, it was found that although intracellular structures labeled with GFP-tagged caveolin were dynamic, GFP-labeled caveolae were very immobile. However, after incubation with methyl- beta-cyclodextrin, distinct caveolae disappeared and the mobility of GFP-tagged caveolin in the plasma membrane increased. Treatment of cells with cytochalasin D caused lateral movement and aggregation of GFP-labeled caveolae. Therefore, both cholesterol and an intact actin cytoskeleton are required for the integrity of GFP-labeled caveolae. Moreover, stimulation with okadaic acid caused increased mobility and internalization of the labeled caveolae. Although the calculated mobile fraction (for t = infinity) of intracellular, GFP-tagged caveolin- associated structures was 70-90%, GFP-labeled caveolae in unstimulated cells had a mobile fraction of <20%, a value comparable to that previously reported for E-cadherin in junctional complexes. We therefore conclude that caveolae are not involved in constitutive endocytosis but represent a highly stable plasma membrane compartment anchored by the actin cytoskeleton.