Characterization of molecular and immune landscape of microvascular invasion in hepatocellular carcinoma and prognostic significance.

Abstract

e16162 Background: Partial hepatectomy is potentially curative treatment in selected patients (pts) with hepatocellular carcinoma (HCC). Microvascular invasion (MVI) is one of the strongest predictors of prognosis and recurrence of HCC. In this study, we analyzed the gene mutation signature and immune factors associated with MVI, and the prognostic value. Methods: Pts who were diagnosed with HCC between Jan 2018 and Sep 2020 in Cancer Hospital of Chinese Academy of Medical Sciences were retrospectively enrolled in this study. Next-generation sequencing (NGS) was performed on tumor tissues after radical partial hepatectomy. The different immune makers (PD1, PD-L1, CD3, CD8, CD68, and CD163) of tumor-infiltrating lymphocytes (TILs) were identified with immunofluorescence-based microenvironment analysis panel (MAP). Results: In the MVI+ group (n = 39, 59.1 %), there were significantly more pts with larger tumor size, and capsules invasion by tumors. The mutation spectra revealed that 61 (92.4%) pts harbored somatic mutations and the most frequently mutated gene was telomerase reverse transcriptase (TERT), which was present in 31.8% (n = 20) HCC pts. Mutations in the promoter of TERT were found in 95.2% (20/21) pts. 90.0% (18/20) had one hotspot point mutation located 124bp upstream of the translation start site. The mutation frequency in the TERT promoter was significantly higher in the MVI+ group compared with the MVI- group (41.0% vs. 14.8%, p < 0.05). Pts with TERT promoter mutations tend to be MVI+ rather than MVI- and more HCC driver mutations were detected in MVI+ pts with TERT promoter mutations (p < 0.05). Based on MAP, we found MVI+ pts had significantly lower CD3+ TILs (p < 0.05). The multivariable analysis indicated that pts with copy number variations (CNV, hazard ratios [HR] 2.62, 95% confidence interval [CI] 1.07-6.40; p = 0.028), elevated PT/INR (HR 0.29, 95% CI 0.11-0.77; p = 0.008), and lower serum prealbumin concentration (PALB, HR 3.03, 95% CI 1.08-8.51; p = 0.027) had significantly shorter recurrence-free survival (RFS) after surgery. Similar findings were also observed for immune factors within cancer parenchyma, including CD68+ (HR 7.14, 95% CI 0.95-53.55; p = 0.025), CD163+ (HR 3.07, 95% CI 1.10-8.53; p = 0.023), CD68+/CD163- (HR 11.35, 95% CI 1.51-85.05; p = 0.003), CD68+/CD163+ (HR 3.51, 95% CI 1.4-8.79; p = 0.004), which indicated tumor-associated macrophage (TAM) infiltration was independent risk factor for RFS. Conclusions: In this study, we characterized the molecular and immune landscape of MVI in HCC patients. MVI presence highly correlated with adverse biological markers, mutations in the promoter of TERT, and higher CD3+ TILs. Some risk factors of HCC recurrence were identified, including CNV, PT/INR, CA 19-9, PALB, and TAM. Transcriptional alterations and immune tumor microenvironment change may contribute to MVI in HCC.