Notably, the comparableaffinity of ponatinib (KD=7.9 nM) andPDA (KD=5.7 nM) for FGFR1 is a result ofthe outstandingly long lifetime of the ponatinib–FGFR1 complex: thedissociation rate constant for ponatinib (koff=1.9×10−4 s−1,corresponding to a half-life (t1/2) for the complex of∼61 min) is ∼50 × slower than that for PDA(koff=9.2 ×10−3 s−1;t1/2=1.3 min). The gene discussed is FGFR1; the disease is Patent ductus arteriosus.