We evaluated the antitumor activity of an FGFRi and an MTKI in a collection of seventeen BC patient-derived xenografts (PDXs) harboring amplification in FGFR1/2/3/4 and in ten patients receiving either an FGFRi/MTKI....High FGFR1-4 mRNA levels but not copy number alteration (CNA) associated with FGFRi response.