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. 2023 Jun 4;13(9):2012–2031. doi: 10.1158/2159-8290.CD-23-0475

Figure 1.

Figure 1. RLY-4008 is a potent and selective irreversible inhibitor of FGFR2. A, Sequence alignment of the kinase domains of FGFR1–4 indicates a high degree of similarity among paralogs. RLY-4008 binding site residues are boxed; residues shown in pink identify amino acid differences between FGFR2 and paralogs within this region. Numbering refers to the FGFR2 IIIc isoform. B, Chemical structure of RLY-4008, N-(4-(4-amino-5-(3-fluoro-4-((4-methylpyrimidin-2-yl)oxy)phenyl)-7-methyl-7H-pyrrolo[2,3-d]pyrimidin-6-yl)phenyl)methacrylamide. C, Crystal structure of RLY-4008 in complex with FGFR2 (PDB: 8STG). Protein is shown in green, and inhibitor carbons are shown in magenta. The Cys491 sulfur is shown in gold and as a covalent adduct with RLY-4008. D and E, Rate of covalent labeling of FGFR2 (red) and FGFR1 (blue) by RLY-4008 (D) and futibatinib (E) as measured by intact mass over time. Triplicate biological replicates are reported. F, RLY-4008 concentration-dependent modification rate against FGFR2 (red) and FGFR1 (blue). RLY-4008 against FGFR2: kinact = 6.45 × 10−2 per second; KI = 1.87 μmol/L; kinact/KI = 3.45 × 10−2 per second/(μmol/L). RLY-4008 against FGFR1: kinact = 2.33 × 10−3 per second; KI = 6.14 μmol/L; kinact/KI = 3.79 × 10−4 per second/(μmol/L). G, Fold change in biochemical IC50 values of the indicated inhibitors between FGFR2 and FGFR1, FGFR3, and FGFR4. Average fold change of three independent experiments each containing two biological replicates is reported. Error bars indicate SD. H, TREEspot depicting selectivity of RLY-4008 screened against 468 kinases via KINOMEscan (DiscoverX, Eurofins). At the test concentration of 500 nmol/L, three kinases showed greater than 75% inhibition: FGFR2 (94.1%), MEK5 (92.4%), and MKNK2 (89%). Image generated using TREEspot Software Tool and reprinted with permission from KINOMEscan, a division of DiscoveRx Corporation, ©DiscoverX Corporation 2010.

RLY-4008 is a potent and selective irreversible inhibitor of FGFR2. A, Sequence alignment of the kinase domains of FGFR1–4 indicates a high degree of similarity among paralogs. RLY-4008 binding site residues are boxed; residues shown in pink identify amino acid differences between FGFR2 and paralogs within this region. Numbering refers to the FGFR2 IIIc isoform. B, Chemical structure of RLY-4008, N-(4-(4-amino-5-(3-fluoro-4-((4-methylpyrimidin-2-yl)oxy)phenyl)-7-methyl-7H-pyrrolo[2,3-d]pyrimidin-6-yl)phenyl)methacrylamide. C, Crystal structure of RLY-4008 in complex with FGFR2 (PDB: 8STG). Protein is shown in green, and inhibitor carbons are shown in magenta. The Cys491 sulfur is shown in gold and as a covalent adduct with RLY-4008. D and E, Rate of covalent labeling of FGFR2 (red) and FGFR1 (blue) by RLY-4008 (D) and futibatinib (E) as measured by intact mass over time. Triplicate biological replicates are reported. F, RLY-4008 concentration-dependent modification rate against FGFR2 (red) and FGFR1 (blue). RLY-4008 against FGFR2: kinact = 6.45 × 10−2 per second; KI = 1.87 μmol/L; kinact/KI = 3.45 × 10−2 per second/(μmol/L). RLY-4008 against FGFR1: kinact = 2.33 × 10−3 per second; KI = 6.14 μmol/L; kinact/KI = 3.79 × 10−4 per second/(μmol/L). G, Fold change in biochemical IC50 values of the indicated inhibitors between FGFR2 and FGFR1, FGFR3, and FGFR4. Average fold change of three independent experiments each containing two biological replicates is reported. Error bars indicate SD. H, TREEspot depicting selectivity of RLY-4008 screened against 468 kinases via KINOMEscan (DiscoverX, Eurofins). At the test concentration of 500 nmol/L, three kinases showed greater than 75% inhibition: FGFR2 (94.1%), MEK5 (92.4%), and MKNK2 (89%). Image generated using TREEspot Software Tool and reprinted with permission from KINOMEscan, a division of DiscoveRx Corporation, ©DiscoverX Corporation 2010.