Discovery of Ligands for the TNFR1 Extracellular Domain Using Fragment-Based Drug Discovery

Tumor necrosis factor receptor 1 (TNFR1) plays a major role in immunoregulation. It is involved in inflammatory and autoimmune diseases like rheumatoid arthritis, psoriasis, Alzheimer's disease, and multiple sclerosis. However, few small-molecule inhibitors of TNFR1 have been reported, even though they constitute a good alternative to already existing antibody therapies targeting the TNF pathway. Here, we report the discovery of a new class of molecules for the extracellular domain of TNFR1 using a fragment-based approach through primary screening by NMR spectroscopy, followed by orthogonal validation by surface plasmon resonance (SPR) and X-ray crystallography. Guided by these results, we have synthesized 46 analogs with micromolar potency showing up to ∼10-fold improved affinity toward TNFR1 compared to the fragment hits. These results can provide a structural basis for the discovery of novel TNFR1 inhibitors in the future.