Safety and clinical activity of 1L atezolizumab + bevacizumab in a phase Ib study in hepatocellular carcinoma (HCC).

Abstract

4074Background: Advanced HCC is a lethal cancer with a high unmet medical need. Single-agent immunotherapy with PD-L1/PD-1 blockade or treatment (Tx) with anti-angiogenic bevacizumab (bev; anti-VEGF) has shown modest activity in HCC. We hypothesized that the combination of atezolizumab (atezo; anti–PD-L1) + bev results in a greater clinical benefit due to the additional immunomodulatory effects of bev (increased DC maturation, enhanced T-cell infiltration, reduced MDSCs and Tregs in tumors), which create a more favorable tumor microenvironment that potentiates the efficacy of atezo. Methods: Patients (pts) with unresectable or metastatic HCC who were naive to systemic Tx were enrolled in a Phase Ib study cohort (NCT02715531). Pts received atezo (1200 mg) + bev (15 mg/kg) IV every 3 weeks until loss of clinical benefit or unacceptable toxicity. The primary objective was to assess the safety and tolerability of the combination. Secondary efficacy endpoints included ORR, PFS, DOR and time to progression (TTP...