IMbrave150: Exploratory efficacy and safety results of hepatocellular carcinoma (HCC) patients (pts) with main trunk and/or contralateral portal vein invasion (Vp4) treated with atezolizumab (atezo) + bevacizumab (bev) versus sorafenib (sor) in a global Ph III study.

Abstract

4073 Background: Atezo + bev has been approved in >60 countries for pts with unresectable HCC who have not received prior systemic therapy, based on IMbrave150 (NCT03434379; Finn RS NEJM 2020). Due to their poor prognosis and the hemodynamic changes from increased portal vein pressure, pts with main portal vein tumor thrombus are often excluded from pivotal HCC trials. Here, we report exploratory efficacy and safety results of pts with Vp4 (presence of a tumor thrombus in the main trunk and/or contralateral portal vein) using updated IMbrave150 data (Finn RS ASCO GI 2021). Methods: Pts were randomized 2:1 to atezo 1200 mg IV q3w + bev 15 mg/kg IV q3w or sor 400 mg bid until unacceptable toxicity or loss of clinical benefit per investigator. IMbrave150 enrolled 501 systemic treatment (tx)–naive unresectable HCC pts, ≥1 measurable untreated lesion (RECIST 1.1), Child-Pugh class A liver function and ECOG PS 0/1, including 73 (15%) Vp4 pts. This post hoc exploratory analysis was conducted with a median follow-up of 15.6 mo in ITT pts. Results: Of the Vp4 pts, 48 received atezo + bev and 25 received sor. Median OS (mOS) was 7.6 vs 5.5 mo (HR, 0.62; 95% CI: 0.34, 1.11) and median PFS (mPFS) per independent review facility (IRF)–assessed RECIST 1.1 was 5.4 vs 2.8 mo (HR, 0.62; 95% CI: 0.35, 1.09) with atezo + bev and sor, respectively. ORR per IRF RECIST 1.1 was 23% (11/47) with atezo + bev (2 [4%] pts had CR) vs 13% (3/23) with sor (1 [4%] pt had CR). All-grade variceal bleeding was higher with atezo + bev in Vp4 (13.6%) vs rest of ITT pts (2.5%). See table for further efficacy and safety data. Conclusions: The benefits of atezo + bev over sor in Vp4 pts are consistent with those in ITT pts across all efficacy endpoints, despite the expected disease-intrinsic increase in variceal bleeding in Vp4 vs rest of ITT pts. The overall positive benefit-risk profile supports the use of atezo + bev in pts with Vp4. Clinical trial information: NCT03434379. [Table: see text]