Supplementary Material for: Phase 2 Study of the PD-1 Inhibitor Serplulimab Plus the Bevacizumab Biosimilar HLX04 in Patients with Previously Treated Advanced Hepatocellular Carcinoma

Introduction: Current treatments for patients with previously treated advanced hepatocellular carcinoma (HCC) provide modest survival benefits. We evaluated the safety and antitumor activity of serplulimab, an anti-PD-1 antibody, plus the bevacizumab biosimilar HLX04 in this patient population. Methods: In this open-label, multicenter, phase 2 study in China, patients with advanced HCC who failed prior systemic therapy received serplulimab 3 mg/kg plus HLX04 5 mg/kg (group A) or 10 mg/kg (group B) intravenously every 2 weeks. The primary endpoint was safety. Results: As of April 8, 2021, 20 and 21 patients were enrolled into group A and B, and they had received a median of 7 and 11 treatment cycles, respectively. Grade ≥3 treatment-emergent adverse events were reported by 14 (70.0%) patients in group A and 12 (57.1%) in group B. Most immune-related adverse events were grade ≤3. The objective response rate was 30.0% (95% confidence interval (CI), 11.9–54.3) in group A and 14.3% (95% CI, 3.0–36.3) in group B. Median duration of response was not reached (95% CI, 3.3–not evaluable (NE)) in group A and was 9.0 months (95% CI, 7.9–NE) in group B. Median progression-free survival was 2.2 months (95% CI, 1.4–5.5) and 4.1 months (95% CI, 1.5–NE), and median overall survival was 11.6 months (95% CI, 6.4–NE) and 14.3 months (95% CI, 8.2–NE) in group A and B, respectively. Conclusion: Serplulimab plus HLX04 showed a manageable safety profile and antitumor activity in patients with previously treated advanced HCC.