Introducing yttrium-90 radioembolization to atezolizumab and bevacizumab regimen for intermediate and advanced stage hepatocellular carcinoma: A preliminary report of safety and effectiveness

e16231 Background: The IMbrave150 Phase III trial demonstrated superiority of atezolizumab and bevacizumab (Atezo/Bev) over sorafenib in unresectable hepatocellular carcinoma (HCC). Combined radiotherapy and immune checkpoint inhibitors have been shown to induce synergistic effects in treatment of HCC and other solid tumors. Barcelona Clinic Liver Cancer 2022 updated guidelines recommend consideration of transarterial radioembolization (TARE) for early stage and very early stage HCC. The present study sims to evaluate the safety and effectiveness of combining TARE and the Atezo/Bev regimen for intermediate and advanced stage HCC. Methods: Retrospective review at a single institution was performed between May 2021 and December 2022. Patients who received TARE using yttrium-90 (Y90) with concomitant or sequential Atezo/Bev systemic treatment were included. The following outcomes were retrieved: overall survival (OS), radiologic tumor response, progression-free survival, technical adverse events related to TARE, and toxicity based on the National Cancer Institute–Common Terminology Criteria for Adverse Events version 5.0. Results: Ten consecutive patients (9 male, 1 female) with unresectable HCC received TARE and Atezo/Bev were included. A total 21 of doses of Y90 were administered with a median target dose of 156 Gy. Tumor control was achieved in all target lesions (100%) based on modified Response Evaluation Criteria in Solid Tumors criteria. Overall disease progression occurred in 4 patients after TARE with a 6- month PFS of 80% (95%CI: 40.9-95.6%) and 12-month PFS of 53.3% (17.3%-79.8%). Two patients died during follow-up, with 6-month and 12-month OS rates of 88.9% (95%CI: 43.3-98.4%) and 76.2% (95%CI: 33.2-93.5%), respectively. One patient developed grade 3 transaminitis and hypoglobulinemia. Atezo/Bev was switched to Lenvatinib in one patient due to myositis. Bevacizumab was held in one patient due to suspected transient ischemic attack. Conclusions: This small patient cohort demonstrated preliminary safety and effectiveness of TARE in combination with Atezo/Bev in treating intermediate and advanced stage HCC. Further prospective and comparative studies with large sample sizes are warranted.