Mapracorat

Mapracorat is a nonsteroidal Selective Glucocorticoid Receptor Agonist (SEGRA) that is presumed to have a better therapeutic index compared to classical glucocorticoids.

To compare the efficacy and safety of mapracorat with classical glucocorticoids used for the treatment of allergic skin diseases in dogs.

Six laboratory beagles.

The effect of mapracorat on lipopolysaccharide‐induced TNFα secretion from canine peripheral blood derived mononuclear cells (PBMC) was tested. In vivo, mapracorat was compared to triamcinolone acetonide using a skin inflammation model. Skin fold thickness was determined after daily administration of mapracorat and triamcinolone acetonide over 14 days.

Mapracorat concentration dependently inhibited TNFα secretion from activated canine PBMC with a half maximal inhibitory concentration (IC50) value of approximately 0.2 nmol/L. Intradermal injection of compound 48/80 (50 μg in 50 μL saline) resulted in a clear wheal and flare reaction over the 60 min observation period. Topical pre‐treatment with mapracorat (0.1%) and triamcinolone acetonide (0.015%) led to significant reduction in the wheal and flare responses compared to vehicle (acetone) treated areas. However, once daily topical administration of triamcinolone acetonide significantly reduced skin fold thickness from day 8 to 14, whereas no such reduction was observed for mapracorat.

These results demonstrate that mapracorat has comparable anti‐inflammatory efficacy to classical steroidal glucocorticoids under these experimental settings and maintenance of skin fold thickness indicates a better safety profile compared to triamcinolone acetonide at equipotent concentrations. This profile further suggests that SEGRAs show promise in the management of inflammatory and pruritic skin diseases in dogs.

Background/Aims: Psoriasis plaque tests (PPTs) are important tools in the early phases of antipsoriatic drug development. Two distinct PPT design variants (open vs. occluded drug application) are commonly used, but no previous work has aimed to directly compare and contrast their performance. Methods: We compared the antipsoriatic efficacy of mapracorat 0.1% ointment and reference drugs reported in 2 separate studies, representing open and occluded PPT designs. The drug effect size was measured by sonography (mean change in echo-poor band thickness), chromametry, and standardized clinical assessment. Results: Antipsoriatic effects were detectable for the study drugs in both occluded and open PPTs. Differences between the potency of antipsoriatic drugs and vehicle were observable. The total antipsoriatic effect size appeared to be higher in the occluded PPT than the open PPT, despite the shorter treatment duration (2 vs. 4 weeks). Effect dynamics over time revealed greater differences between some study drugs in the open PPT compared to the occluded PPT. Conclusion: Taking the higher technical challenges for the open PPT into account, we recommend the occluded PPT as a standard screening setting in early drug development. In special cases, considering certain drug aspects or study objectives that would require procedural adaptations, an open PPT could be the better-suited design. Finally, both PPT models show clear advantages: classification as phase I studies, small number of psoriatic subjects, relatively short study duration, excellent discrimination between compounds and concentrations, parallel measurement of treatment response, and go/no go decisions very early in clinical development.