Remote-site Allosteric Control of DFG Dynamics Enables Rational Design of the First Reversible Macrocyclic FGFR2 Inhibitors

FGFR alterations drive multiple cancers. While approved pan-FGFR inhibitors show clinical benefit, their use is limited by FGFR1/4-related toxicity and acquired resistance. We discovered that the selective FGFR2 inhibition described for the covalent inhibitor lirafugratinib is achieved through remote-site allosteric regulation of non-conserved residues FGFR1 V607 and FGFR2 L610, which differentially modulate the conformation of the FGFR1 and FGFR2 DFG motifs influencing covalent warhead accessibility. Guided by this insight, we designed the first reversible macrocyclic FGFR2 selective inhibitor 11c. It exhibits strong selectivity over FGFR1/3/4 (11-, 4.5-and 28.7-fold), potently inhibits FGFR2-driven tumor cells (IC50 = 2.5-15 nM), overcomes FGFR2 gatekeeper and molecular-brake mutations, and shows favorable oral pharmacokinetics and in vivo efficacy without inducing diarrhea or hyperphosphatemia. This work provides a promising macrocyclic lead for FGFR2-driven cancers.