A decrease in FGFR3 mutations with BGJ398 treatment appeared to correlate with a longer time on study and a greater percentage decrease in tumor size from baseline...An analysis of clinical outcome limited to patients with documented activating mutations in FGFR3 (S249C, R248C, Y375C and Y373C) yields a confirmed response rate of 28.6% (16 of 56 patients); including unconfirmed responses, the response rate rises further to 42.9% (24 of 56 patients).