In a first-in-human study with BLU-554 in patients with HCC, the ORR was 17% in FGF19-positive patients (median duration of response: 5.3 months [95% CI: 3.7-not reached]) and 0% in FGF19-negative patients, showing a correlation between tumor response and FGF19 expression. Here, FGF19 is linked to hepatocellular carcinoma.