Anti-PD-L1 envafolimab combined with anti-VEGF suvemcitug in pretreated solid tumors and hepatocellular carcinoma: an open-label phase II study with safety run-in stage.

Background: Immune checkpoint inhibitors (ICIs) combined with anti-vascular endothelial growth factor (VEGF) have been the standard first-line treatment of hepatocellular carcinoma (HCC). However, the efficacy of this combination in post-line treatment is still unknown. This study aimed to evaluate the efficacy and safety of the combination of anti-PD-L1 envafolimab and novel humanized anti-VEGF suvemcitug as second-line treatment for patients with HCC.

Methods: This open-label, prospective phase II clinical study (NCT05148195) comprised safety run-in stage and dose expansion stage of HCC cohort. Eligible patients were aged ≥ 18 years and had undergone at least a prior line of treatment. Patients received fixed-dose envafolimab and suvemcitug until termination of disease progression, unacceptable toxicities, or withdrawal. The primary endpoint of safety run-in stage was recommended dose (RD), and dose expansion stage was objective response rate (ORR).

Results: As of August 10, 2023, no dose-limiting toxicity was observed in six patients in the safety-run-in stage, and 2 mg/kg dose every 3 weeks was declared the RD of suvemcitug. Among 20 patients with HCC, the median age was 54.5 (range, 42-70) years. Of these patients, 20 (100.0%) received ≥ one prior line treatment, with 20 (100%) received tyrosine kinase inhibitor (TKI) treatment and 8 (40.0%) received prior ICI treatment. The ORR was 10.0% (95% confidence interval (CI), 1.2-31.7), DCR was 65.0% (95% CI, 40.8-84.6), and DoR was not reached (NR). With a median follow-up of 13.9 months, the median progression-free survival (PFS) and median overall survival (OS) were 4.3 months (95% CI, 1.4-8.1) and 10.7 months (95% CI, 6.0-not evaluable [NE]), respectively. Treatment-related adverse events (TRAEs) of grade ≥ 3 occurred in 40% patients, with proteinuria (20.0%, 4/20) being the most frequent. The ORR of no lung metastasis, prior first-line treatment and IO naïve treatment subgroup was 16.7%.

Conclusions: The combination of envafolimab and suvemcitug showed a tolerable safety profile and promising antitumor activity in HCC patients who failed later-line treatment.