Currently, therapeutic combinations of immune checkpoint inhibitors (ICIs) with anti-angiogenic agents have shown promising outcomes and have the potential to establish a new standard of care. The efficacy and safety of the first-line combination of envafolimab (an ICI) and lenvatinib (an anti-tumor angiogenesis drug) for the treatment of patients with inoperable hepatocellular carcinoma (HCC) have not been demonstrated. Unresectable HCC patients with an Eastern Cooperative Oncology Group (ECOG) physical status score ≤ 1 and a Child-Pugh score ≤ 7 who had not received systemic therapy were included in this single-arm, exploratory, multicentre phase II clinical study. All patients were required to meet the criteria of being at least 18 years of age, having no history of other malignancies, and existing at least one measurable lesion. The patients were treated with envafolimab (150 mg, QW, subcutaneous) in combination with lenvatinib (12 mg for patients weighing over 60 kg, 8 mg for patients weighing under 60 kg). The co-primary endpoint of the study was overall survival (OS), while surrogate endpoints included progression-free survival (PFS), objective response rate (ORR), disease control rate (DCR), and safety. Between March 2022 and April 2023, 36 patients were enrolled, 30 of whom were treated with envafolimab plus lenvatinib. At data cutoff, the median follow-up duration was 20 months (95% CI 18.9-21.1). Among the 30 assessable patients (patients treated according to the trial protocol), the median overall survival (mOS) and median progression-free survival (mPFS) for the therapy comprising envafolimab alongside lenvatinib were 18.5 months (95% CI 13.2-23.8) and 9.4 months (95% CI 1.6-15.6), respectively. The ORR and the DCR (evaluated according to mRECIST criteria) reached 40% and 80%, respectively. In terms of safety, 23 patients (76.7%) experienced at least one treatment-related adverse event (TRAE), of which the most common was elevated aspartate aminotransferase (AST, 23.3%). Furthermore, grade 3 and higher TRAEs occurred in 30%. This study demonstrates that envafolimab in combination with lenvatinib exhibits favourable anti-cancer activity and a manageable safety profile for the first-line treatment of patients with unresectable HCC.© 2024. The Author(s).