Sintilimab combined with bevacizumab biosimilar as a conversion therapy in potentially resectable intermediate-stage hepatocellular carcinoma (HCC): Updated results of a phase II trial.

e16220 Background: The combination of Sintilimab (a PD-1 antibody) and bevacizumab (bev) biosimilar improved progression-free survival and overall survival in unresectable or advanced HCC as compared with sorafenib in ORIENT-32 study and was approved as first-line treatment for unresectable HCC in China. We assessed the efficacy and safety of the combination therapy as conversion therapy for potentially resectable intermediate-stage HCC. Methods: Treatment-naïve patients (pts) with potentially resectable intermediate stage (BCLC stage B) HCC were enrolled in this phase II trial (NCT04843943). Eligible pts received sintilimab (200 mg, IV, D1) and bev (15 mg/kg, IV, D1) per 3 weeks. Tumor response and resectability were assessed every 6 weeks per RECIST v1.1. Pts with evaluations of partial response (PR) or at least two consecutive stable disease (SD) and eligible for R0 resection were referred for hepatectomy, then continued with sintilimab/bev for at most 12 months. Primary endpoints were event-free survival (EFS) (time from study enrollment to tumor progression, disease recurrence after surgery, or death from any cause) and treatment safety. Secondary endpoints included R0 resection rate, pathologic response, objective response rate (ORR), and disease control rate (DCR). Results: At data cutoff on Feb 7, 2023, 30 pts with BCLC-B stage HCC were enrolled. Of them, 25 pts (83.3%) were up-to-7 criteria out. The median follow-up time was 15.3 months (interquartile range [IQR] 13.8-17.6). ORR and DCR were 26.7% and 90.0% (8 PR and 19 SD). 17 pts (56.7%) met the pre-designated criteria for hepatectomy and received liver resection, including 7 pts were evaluated as PR and 10 as SD before surgery. The median time from initiation of sintilimab/bev to liver resection was 4.3 months (IQR 2.3-5.6). No postoperative mortality was observed. 2 pts had a pathological complete response. Median EFS was 13.8 months (95%CI, 10.3-17.3), and the 6-month and 12-month EFS rates were 76% and 60%, respectively. 3 pts died, and OS data was not mature. Most treatment-related AEs (TRAE) were grade 1-2, and grade 3/4 TRAEs occurred in 7 pts (23.3%). 9 serious adverse events occurred, and 3 of them were treatment associated. Conclusions: For pts with potentially resectable intermediate-stage HCC, sintilimab/bev in combination with liver resection was safe and may improve long-term survival. Clinical trial information: NCT04843943 .