The αvβ6 integrin plays a key role in the activation of transforming growth factor-β (TGFβ), a pro-fibrotic mediator that is pivotal to the development of idiopathic pulmonary fibrosis (IPF). We identified a selective small molecule αvβ6 RGD-mimetic, GSK3008348, and profiled it in a range of disease relevant pre-clinical systems. To understand the relationship between target engagement and inhibition of fibrosis, we measured pharmacodynamic and disease-related end points. Here, we report, GSK3008348 binds to αvβ6 with high affinity in human IPF lung and reduces downstream pro-fibrotic TGFβ signaling to normal levels. In human lung epithelial cells, GSK3008348 induces rapid internalization and lysosomal degradation of the αvβ6 integrin. In the murine bleomycin-induced lung fibrosis model, GSK3008348 engages αvβ6, induces prolonged inhibition of TGFβ signaling and reduces lung collagen deposition and serum C3M, a marker of IPF disease progression. These studies highlight the potential of inhaled GSK3008348 as an anti-fibrotic therapy.

BackgroundThe CC-chemokine receptor 4 (CCR4) is thought potentially to play a critical role in asthma pathogenesis due to its ability to recruit type 2 T-helper lymphocytes to the inflamed airways. Therefore, CCR4 provides an excellent target for anti-inflammatory therapy.MethodsThe safety, tolerability, pharmacokinetics and pharmacodynamics of the CCR4 antagonist GSK2239633, N-(3-((3-(5-chlorothiophene-2-sulfonamido)-4-methoxy-1H-indazol-1-yl)methyl)benzyl)-2-hydroxy-2-methylpropanamide, were examined in healthy males. Two studies were performed: 1) an open-label, study in which six subjects received a single intravenous infusion of [14C]-GSK2239633 100 μg (10 kBq) (NCT01086462), and 2) a randomised, double-blind, placebo-controlled, cross-over, ascending dose study in which 24 subjects received single oral doses of GSK2239633 150–1500 mg (NCT01371812).ResultsFollowing intravenous dosing, plasma GSK2239633 displayed rapid, bi-phasic distribution and slow terminal elimination (t½: 13.5 hours), suggesting that GSK2239633 was a low to moderate clearance drug. Following oral dosing, blood levels of GSK2239633 reached Cmax rapidly (median tmax: 1.0–1.5 hours). Estimated GSK2239633 bioavailability was low with a maximum value determined of only 16%. Food increased GSK2239633 systemic exposure (as assessed by AUC and Cmax). Increases in AUC and Cmax were less than dose proportional. Adverse events were reported by three subjects (50%) following intravenous administration, and by 19 subjects (79%) following oral administration; most (46/47; 98%) events were mild/moderate in intensity. GSK2239633 1500 mg inhibited thymus- and activation-regulated chemokine-induced (TARC) actin polymerisation reaching a mean CCR4 occupancy of 74%.ConclusionIn conclusion, GSK2239633 was well-tolerated and capable of inhibiting TARC from activating the CCR4 receptor.

A series of indazole arylsulfonamides were synthesized and examined as human CCR4 antagonists. Methoxy- or hydroxyl-containing groups were the more potent indazole C4 substituents. Only small groups were tolerated at C5, C6, or C7, with the C6 analogues being preferred. The most potent N3-substituent was 5-chlorothiophene-2-sulfonamide. N1 meta-substituted benzyl groups possessing an α-amino-3-[(methylamino)acyl]-group were the most potent N1-substituents. Strongly basic amino groups had low oral absorption in vivo. Less basic analogues, such as morpholines, had good oral absorption; however, they also had high clearance. The most potent compound with high absorption in two species was analogue 6 (GSK2239633A), which was selected for further development. Aryl sulfonamide antagonists bind to CCR4 at an intracellular allosteric site denoted site II. X-ray diffraction studies on two indazole sulfonamide fragments suggested the presence of an important intramolecular interaction in the active conformation.

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