Efficacy and Safety of PD-1/PD-L1 Inhibitors in Advanced Hepatocellular Carcinoma: A Systematic Review and Meta-analysis

INTRODUCTION

Programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) inhibitors have been increasingly employed for the treatment of various cancers in clinical practice. This study aimed to systematically evaluate the efficacy and safety of PD-1/PD-L1 inhibitors for advanced hepatocellular carcinoma (HCC).

METHODS

PubMed, EMBASE, Cochrane library, Web of Science, and Abstracts of American Society of Clinical Oncology proceedings databases were searched. Objective response rate (ORR), disease control rate (DCR), median progression-free survival (PFS), median overall survival (OS), and incidence of adverse events (AEs) and drug withdrawal were pooled. Odds ratio (OR) and hazard ratio (HR) were calculated to analyze the difference in the ORR, DCR, PFS, and OS between groups.

RESULTS

Among the 14,902 initially identified papers, 98 studies regarding use of PD-1/PD-L1 inhibitors in advanced HCC were included. Based on different criteria of response in solid tumors, the pooled ORR, DCR, and median PFS was 16-36%, 54-74%, and 4.5-6.8 months, respectively. The pooled median OS was 11.9 months. Compared to multitarget tyrosine kinase inhibitors (TKIs), PD-1/PD-L1 inhibitors monotherapy significantly increased ORR (OR 2.73, P < 0.00001) and OS (HR 0.97, P = 0.05), and PD-1/PD-L1 inhibitors combined with TKIs significantly increased ORR (OR 3.17, P < 0.00001), DCR (OR 2.44, P < 0.00001), PFS (HR 0.58, P < 0.00001), and OS (HR 0.58, P < 0.00001). The pooled incidence of all-grade AEs, grade ≥ 3 AEs, and drug withdrawal was 71%, 25%, and 7%, respectively.

CONCLUSION

On the basis of the present systematic review and meta-analysis, PD-1/PD-L1 inhibitors should be the preferred treatment choice for advanced HCC owing to their higher antitumor effect and improved outcomes.

Recent Advances and Future Prospects in Immune Checkpoint (ICI)-Based Combination Therapy for Advanced HCC

Advanced, unresectable hepatocellular carcinoma has a dismal outcome. Multiple immune checkpoint inhibitors (ICIs) targeting the programmed-cell death 1 pathway (PD-1/L1) have been approved for the treatment of advanced HCC. However, outcomes remain undesirable and unpredictable on a patient-to-patient basis. The combination of anti-PD-1/L1 with alternative agents, chiefly cytotoxic T-lymphocyte antigen-4 (CTLA-4) ICIs or agents targeting other oncogenic pathways such as the vascular endothelial growth factor (VEGF) pathway and the c-MET pathway, has, in addition to the benefit of directly targeting alterative oncogenic pathways, in vitro evidence of synergism through altering the genomic and function signatures of T cells and expression of immune checkpoints. Several trials have been completed or are underway evaluating such combinations. Finally, studies utilizing transcriptomics and organoids are underway to establish biomarkers to predict ICI response. This review aims to discuss the biological rationale and clinical advances in ICI-based combinations in HCCs, as well as the progress and prospects of the search for the aforementioned biomarkers in ICI treatment of HCC.