Alpha fetoprotein (AFP) response and efficacy outcomes in the phase III CELESTIAL trial of cabozantinib (C) versus placebo (P) in advanced hepatocellular carcinoma (HCC).

423Background: AFP response, defined as a decrease in serum levels of the tumor marker AFP after therapy, may be associated with improved survival of patients (pts) with HCC treated with locoregional or systemic therapy, and high baseline AFP levels may be associated with poor prognosis. In the phase III CELESTIAL trial (NCT01908426), C, an inhibitor of MET, VEGFR, and AXL, significantly improved overall survival (OS) and progression-free survival (PFS) versus P in pts with previously treated advanced HCC. Here we evaluate clinical outcomes with C in CELESTIAL based on AFP response or progression on treatment. Methods: 707 pts were randomized 2:1 to receive C (60 mg daily) or P. Eligible patients had a pathologic diagnosis of HCC, Child-Pugh score A, and ECOG PS ≤ 1. Pts received prior sorafenib and ≤ 2 lines of prior systemic therapy for HCC. Serum AFP levels were measured centrally at baseline and every 8 weeks thereafter. Outcomes were evaluated for pts with baseline AFP ≥ 20 ng/mL based on AFP respons...