Identification of orally bioavailable small-molecule inhibitors of hematopoietic prostaglandin D2 synthase using X-ray fragment based drug discovery

Using X-ray crystallographic screening, fragments 4 and 6 were identified as inhibitors of hematopoietic prostaglandin D2 synthase (H-PGDS). Both fragments induced a small protein movement in the X-ray crystal structure relative to the apo structure, where the highly polar nature of the ligand complemented the induced protein conformation. The manuscript describes the fragment optimisation of 4 and 6 followed by fragment growth to lead molecule 10. This showed favourable physicochemical properties and evidence of oral activity in blocking PGD2 generation in vivo.