Phase Ib/II trial to evaluate the safety and efficacy of atezolizumab and bevacizumab as adjuvant therapy following carbon-ion radiotherapy in hepatocellular carcinoma (VANGUARD): study protocol

Introduction The establishment of an effective strategy for recurrence prevention following curative treatment for hepatocellular carcinoma (HCC), including radiotherapy, remains a critical unmet clinical need. Despite favourable local control and safety profiles, recurrence after particle therapy remains a major challenge, highlighting the need for effective adjuvant strategies to improve long-term outcomes.

The present phase Ib/II trial is designed to evaluate the safety and efficacy of atezolizumab plus bevacizumab (Atezo+Bev) administered after carbon-ion radiotherapy (C-ion RT) in patients with unresectable non-metastatic large HCC. This study aims to explore the potential of this multimodal approach as a novel adjuvant strategy to improve outcomes in patients at high risk of recurrence.

Methods and analysis This is a phase Ib/II, single-arm clinical trial designed to evaluate the safety and efficacy of adjuvant Atezo+Bev following C-ion RT in patients with HCC. Eligible patients will be enrolled in the first registration phase.

C-ion RT (60 Gy) will be administered over four consecutive treatment days ideally within one calendar week.