ABSTRACT: Real-world clinical cases of molecularly targeted agent (MTA) administration to patients with advanced hepatocellular carcinoma (HCC) with ≥50% liver occupation have been reported, but treatment outcomes have rarely been described. We have encountered several cases in which albumin-bilirubin (ALBI) scores deteriorated markedly and C-reactive protein (CRP) levels elevated in the early post-dose period. The present study therefore investigated early clinical changes in ALBI score and CRP levels after initiating MTA in advanced HCC patients with ≥50% liver occupation, focusing on antitumor response at 6 weeks.This retrospective study included 46 HCC patients with liver occupation ≥50% and 191 patients with <50%, Child-Pugh score ≤7, and Eastern Cooperative Oncology Group Performance Status scores of 0 or 1, who were treated with sorafenib or lenvatinib as first-line systemic therapy at our hospital between June 2011 and January 2020. We analyzed their medical records up to March 2020 and investigated the outcomes and changes in CRP and ALBI scores classified according to antitumor response at 6 weeks.Overall survival was significantly longer in patients with partial response (PR) + stable disease (SD) (13.7 months) than in patients with progressive disease (PD) (1.7 months, P < .001) in the ≥50% group. Patients with antitumor response of PR + SD at 6 weeks in the ≥50% group showed more marked deterioration of ALBI score at 2 weeks than those in the <50% group. These significant differences between groups had again disappeared at 4 and 6 weeks. Focusing on patients with PD at 6 weeks, ALBI score deteriorated over time in both groups. Regarding CRP, on 6-week PR + SD patients, a significant increase in CRP levels at 1 and 2 weeks was evident in the >50% group compared to the <50% group. These significant differences between groups had again disappeared at 4 and 6 weeks. In PD patients, no difference between groups in CRP elevation occurred at 1 and 2 weeks.In MTA treatment for patients with ≥50% liver occupation, to obtain an antitumor response of PR + SD, adequate management might be important considering transient deteriorated ALBI scores and elevated CRP levels.