Approaching the tumor microenvironment in patients with advanced hepatocellular carcinoma using needle biopsy samples.

Abstract

334 Background: Currently, combined immunotherapy of atezolizumab (anti-PD-L1 antibody) plus bevacizumab (a humanized anti-VEGF monoclonal antibody) is the standard first-line treatment in patients with advanced hepatocellular carcinoma (HCC). At the threshold of this new era, there is limited information about tumor microenvironment (TME) in advanced HCC. Several studies on TME in HCC have analyzed samples obtained via hepatic resection. In general, hepatic resection is indicated for patients with limited size and number of intrahepatic nodules, i.e., early stage HCC. In contrast, most patients who have an indication for systemic therapy have developed macroscopic vascular invasion (MVI) or/and extrahepatic metastasis, namely in advanced stage HCC. Progression from an early stage HCC to an advanced stage HCC involves a lengthy clinical course, therefore, the TME at the time of initial diagnosis may differ from that at the time of systemic therapy indication. The present study was aimed to analyze the TME by using needle biopsy samples obtained prior to initiation of systemic therapy in patients with advanced HCC. Methods: Between March 2019 and May 2020, 80 patients underwent liver tumor biopsy at the time of indication for systemic chemotherapy. HCC was confirmed via pathological examination in 70 patients and their samples were analyzed. Microsatellite instability (MSI) was evaluated using polymerase chain reaction. Programed death-ligand 1 (PD-L1) expression and the levels of tumor-infiltrating lymphocytes (TIL) were evaluated using immunohistochemical staining. PD-L1 expression was defined as per the tumor proportion score (TPS; the number of PD-L1-positive cells/total number of tumor cells) and was classified as low (TPS < 1%) or high (TPS >1%). Levels of TIL were defined as the mean number of CD8-positive lymphocytes in the tumor per 1 mm2 and classified as low or high using the median value. Results: Out of the 70 tumors, one was MSI-high and 69 were MSI-negative. The PD-L1 expression was < 1% in 50 samples, 1%–10% in 12, 11%–20% in 7, and 21%–30% in 1. The median level of TIL was 266/mm2. PD-L1highTILhighwas present in 20.0%, PD-L1lowTILlowin 38.5%, PD-L1highTILlowin 8.6%, and PD-L1lowTILhighin 32.9%. In the MSI-high tumor, PD-L1 expression was < 1% and the level of TIL was 142/mm2. High PD-L1 expression and high levels of TIL were associated with hepatitis C virus infection, high alpha-fetoprotein levels, and presence of MVI respectively. We are currently performing RNA-sequencing in order to obtain more details about TME in patients with advanced HCC. Conclusions: MSI-high advanced HCC was detected in 1.4% patients and was not necessarily associated with a “hot” immune microenvironment. PD-L1 expression and levels of TIL were associated with some clinical parameters. In the present study, we also reported the changes in the TME over time.