FIIN-3 is an irreversible inhibitor of FGFR with an IC 50 of 13.1, 21, 31.4, and 35.3 nM for FGFR1 , FGFR2 , FGFR3 and FGFR4 , respectively. In Vitro FIIN-3 potently inhibits both WT FGFRs (EC 50 in the 1- to 41-nM range) and the gatekeeper mutant of FGFR2 (EC 50 of 64 nM). FIIN-3 also strongly inhibits EGFR, with an EC 50 of 43 nM. FIIN-3 shows good potency against gatekeeper mutant V564F; FIIN-3 also is potent against the gatekeeper-plus-1 mutant E565K; FIIN-3 also displays antiproliferative activity (with an EC 50 of 135 nM) against Ba/F3 cells transformed by the EGFR vIII fusion protein, which has a WT EGFR kinase domain. FIIN-3 shows even better activity against EGFR mutant L858R (EC 50 of 17 nM) and moderate activity, displaying an EC 50 of 231 nM, against the EGFR mutant L858R/T790M mutant. In WT FGFR2 Ba/F3 cells, FIIN-3 completely inhibits the FGFR2 autophosphorylation on Tyr656/657 at concentrations as low as 3 nM. In FGFR2 V564M Ba/F3 cells, FIIN-3 is capable of inhibiting the FGFR2 mutant V564M autophosphorylation with partial inhibition at 100 nM and complete inhibition observed at 300 nM. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid IC50& Target:FGFR1 13.1 nM (IC 50 ) FGFR2 21 nM (IC 50 ) FGFR3 31.4 nM (IC 50 ) FGFR4 35.3 nM (IC 50 )