- Results: Dose dependent antitumoral activity was observed in both animals models. FGFR inhibition resulted in dynamic modulation of circulating FGF23 levels, as well as inhibition of FGFR downstream signaling in tumor tissue. Frequency of administration impacted on efficacy and potential toxicity. The PKPD relationship was explored. Conclusions: Debio 1347 administration resulted in a dose-dependent reduction in tumor growth in both animal models, displaying either a FGFR fusion or amplification. These results suggest that Debio 1347 will provide therapeutic opportunities for patients who have FGFR genetic alterations.