Benefits of combination therapy with immune checkpoint inhibitors and predictive role of tumour mutation burden in hepatocellular carcinoma: A systematic review and meta-analysis

OBJECTIVES: To investigate the clinical benefits of combination therapy with immune checkpoint inhibitors (ICIs) and best combination regimen for people with advanced hepatocellular carcinoma (HCC) and to explore the predictive performance of tumour mutation burden (TMB). METHODS: We conducted a systematic literature search to identify clinical trials. Meta-analysis and subgroup analyses were performed to estimate the benefits of combination regimens with PD-1/PD-L1 inhibitors for patients with advanced HCC and compare the effectiveness of PD-1/PD-L1 inhibitors and sorafenib as first-line therapy. Individualized analysis and Kaplan-Meier were used to assess the prognostic value of TMB. RESULTS: A total of 29 studies with 5396 patients were included. ICIs' combination therapy had higher ORR (26 % vs 15 %) and DCR (73 % vs 55 %), longer PFS (5.5 vs 3.1 months) and OS (15.9 vs 12.6 months) compared to monotherapy. Anti-PD-1/PD-L1 agents provided improved ORR, DCR, PFS and OS compared to sorafenib. The overall ORs of ORR and DCR in subgroup analysis were 3.49 (95 % CI 2.36-5.17, p < 0.01) and 1.60 (95 % CI 1.15-2.21, p < 0.01). The overall HRs of PFS and OS were 0.68 (95 % CI 0.48-0.96, p = 0.03) and 0.73 (95 % CI 0.62-0.85, p < 0.01). PD-1/PD-L1 inhibitors plus anti-VEGF agents had an advantage in DCR (0.80 vs 0.48, meta-regression = - 0.32, P < 0.001), but an equal ORR (0.29 vs 0.26) compared to dual immune checkpoint inhibitors. The total OS in Dua-ICIs were 16.5 months (95 % CI 14.2-18.7), yet not reached in the major studies of ICI plus anti-VEGF regimen. In individualized analysis, the 1-year OS was superior for patients who had high-TMB (>10, mutations/Mb) than moderate-TMB (1-10, mutations/Mb; 28 % vs 15 %, P = 0.025). CONCLUSION: Immune checkpoint inhibitors' combination therapy improved clinical outcomes in the management of advanced hepatocellular carcinoma. However, the overall objective response rate still did not exceed 30%. PD-1/PD-L1 inhibitors plus anti-angiogenic agents and dual immunotherapy provided significantly increased survival over sorafenib, which also pose new challenges for future research, and more appropriate and guided control regimens are required. Also, TMB may be a promising prognostic biomarker for immunotherapy in HCC. However, the validation of prospective and large sample studies is needed.