Further optimization of an initial DP2 receptor antagonist clinical candidate NVP-QAV680 led to the discovery of a follow-up molecule 2-(2-methyl-1-(4-(methylsulfonyl)-2-(trifluoromethyl)benzyl)-1H-pyrrolo[2,3-b]pyridin-3-yl)acetic acid (compound 11, NVP-QAW039, fevipiprant), which exhibits improved potency on human eosinophils and Th2 cells, together with a longer receptor residence time, and is currently in clinical trials for severe asthma.

Herein we describe the optimization of a series of PDE4 inhibitors, with special focus on solubility and pharamcokinetics, to clinical compound 2, 4-(8-(3-fluorophenyl)-1,7-naphthyridin-6-yl)transcyclohexanecarboxylic acid. Although compound 2 produces emesis in humans when given as a single dose, its exemplary pharmacokinetic properties enabled a novel dosing regime comprising multiple escalating doses and the resultant achievement of high plasma drug levels without associated nausea or emesis.

The optimisation of two series of 4-hydroxybenzothiazolone derived β2-adrenoceptor agonists, bearing α-substituted cyclopentyl and β-phenethyl amino-substituents, as inhaled long-acting bronchodilators is described. Analogues were selected for synthesis using a lipophilicity based hypothesis to achieve the targeted rapid onset of action in combination with a long duration of action. The profiling of the two series led to identification of the α-substituted cyclopentyl analogue 2 as the optimal compound with a comparable profile to the inhaled once-daily long-acting β2-adrenoceptor agonist indacaterol. On the basis of these data 2 was promoted as the backup development candidate to indacaterol from the Novartis LABA project.

Optimization of a 7-azaindole-3-acetic acid CRTh2 receptor antagonist chemotype derived from high throughput screening furnished a highly selective compound NVP-QAV680 with low nM functional potency for inhibition of CRTh2 driven human eosinophil and Th2 lymphocyte activation in vitro. The molecule exhibited good oral bioavailability in the rat, combined with efficacy in rodent CRTh2-dependent mechanistic and allergic disease models and was suitable for clinical development.

The solubility-driven optimization of a series of 1,7-napthyridine phosphodiesterase-4 inhibitors is described. Directed structural changes resulted in increased aqueous solubility, enabling superior pharmacokinetic properties with retention of PDE4 inhibition. A range of potent and orally bioavailable compounds with good in vivo efficacy in animal models of inflammation and reduced emetic potential compared to previously described drugs were synthesized. Compound 2d was taken forward as a clinical candidate for the treatment of COPD.

The synthesis and SAR of 5-heterocycle-substituted aminothiazole adenosine receptor antagonists is described. Several compounds show high affinity and selectivity for the A2B and A3 receptors. One compound (5f) shows good ADME properties in the rat and as such may be an important new compound in testing the current hypotheses proposing a therapeutic role for a dual A2B/A3 antagonist in allergic diseases.