Discovery of a selective and biologically active low-molecular weight antagonist of human interleukin-1β

Human interleukin-1β (hIL-1β) is a pro-inflammatory cytokine involved in many diseases. While hIL-1β directed antibodies have shown clinical benefit, an orally available low-molecular weight antagonist is still elusive, limiting the applications of hIL-1β-directed therapies. Here we describe the discovery of a low-molecular weight hIL-1β antagonist that blocks the interaction with the IL-1R1 receptor. Starting from a low-affinity fragment-based screening hit, it’s receptor based optimization resulted in a compound (S)-2 that binds and antagonizes hIL-1β with single-digit micromolar activity in biophysical, biochemical, and cellular assays. X-ray analysis reveals an allosteric mode of action that involves a hitherto unknown binding site in hIL-1β encompassing two loops involved in IL-1R1/hIL-1β interactions. We show that residues of this binding site are part of a conformationally excited state of the mature cytokine. The compound antagonizes hIL-1β function in cells, including primary human fibroblasts, representing the relevance of this discovery for future development of hIL-1β directed therapeutics.

Ulrich Hommel, Konstanze Hurth, Jean-Michel Rondeau, Anna Vulpetti, Daniela Ostermeier, Andreas Boettcher, Jacob Peter Bräy, Michael Hediger, Sylvie Lehmann, Elke Koch, Anke Blechschmidt, Rina Yamamoto, Valentina Tundo Dottorello, Sandra Haenni-Holzinger, Christian Kaiser, Philipp Lehr, Andreas Lingel, Luca Muredu, Christian Schleberger, Jutta Blank, Paul Ramage, Felix Freuler, Joerg Eder, Frédéric Bornancin