Multicenter Phase 2 Trial of Second-Line Regorafenib in Patients with Unresectable Hepatocellular Carcinoma after Progression on Atezolizumab plus Bevacizumab

<bold>Introduction:</bold> Atezolizumab-bevacizumab (Atezo-Bev) has become the standard first-line treatment for patients with unresectable hepatocellular carcinoma (uHCC). However, data on subsequent treatment after Atezo-Bev failure are lacking. We aimed to investigate the efficacy and safety of regorafenib for uHCC progression after first-line Atezo-Bev. <bold>Methods:</bold> This investigator-initiated, single-arm, phase 2 trial involved two academic centers in Korea. Eligibility criteria included a diagnosis of HCC, prior treatment with at least 2 cycles of Atezo-Bev, and Child-Pugh A liver function. Eligible patients received regorafenib 160 mg once daily for 3 weeks of every 4-week cycle (i.e., 3 weeks on, 1 week off) until progressive disease or intolerable toxicity. The primary endpoint was progression-free survival (PFS). Secondary endpoints included objective response rate, disease control rate according to RECIST v1.1, overall survival (OS), and treatment-related adverse events. <bold>Results:</bold> Forty patients were enrolled from December 2021 through May 2023. The median follow-up duration was 10.1 months (95% confidence interval [CI]: 8.3-12.0). The median PFS was 3.5 months (95% CI: 3.0-3.9). The median OS was 10.5 months (95% CI: 7.1-13.8), and the 6-month OS rate was 65.0%. The objective response rate and disease control rate were 10.0% and 82.5%, respectively. The most common grade 3-4 treatment-related adverse event was thrombocytopenia (5.0%). When stratified according to time to progression on prior Atezo-Bev (first quartile [<2.3 months] vs. second to fourth quartiles [>= 2.3 months]), patients with longer time to progression on prior Atezo-Bev had better OS (15.0 vs. 3.6 months, p < 0.001), objective response rate (13.3% vs. 0%, p = 0.009), and a tendency toward better PFS with regorafenib (3.8 vs. 2.5 months; p = 0.054). <bold>Conclusion:</bold> Second-line regorafenib was effective for treating uHCC progression after first-line Atezo-Bev. The efficacy and safety outcomes from our study were consistent with those observed in the pivotal phase 3 RESORCE trial, which included sorafenib-tolerant/-progressed patients.