Research Progress on Immune Checkpoint Inhibitors in Treatment of Hepatocellular Carcinoma / 肿瘤防治研究

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death, and most patients with HCC are diagnosed at an advanced stage. Before 2017, tyrosine kinase inhibitors were the main drugs for the treatment of advanced hepatocellular carcinoma. With the emergence of immune checkpoint inhibitors (ICIs), immunotherapy has gradually brought new hope to such patients. At present, the combination of ICIs and other systemic or local treatments has become a potential strategy for the treatment of advanced hepatocellular carcinoma, and some of these combinations have been included in large-scale clinical trials. The main challenges of immunotherapy for advanced hepatocellular carcinoma include the exploration of predictive biomarkers, management of immune-related adverse events, and exploration of effective combination regimens. This article provides the latest research progress on the single or combined use of ICIs and other immunotherapy for hepatocellular carcinoma and discusses the limitations of current research and clinical application and the future development direction.

Virus-free and live-cell visualizing SARS-CoV-2 cell entry for studies of neutralizing antibodies and compound inhibitors

The ongoing COVID-19 pandemic, caused by SARS-CoV-2 infection, has resulted in hundreds of thousands of deaths. Cellular entry of SARS-CoV-2, which is mediated by the viral spike protein and host ACE2 receptor, is an essential target for the development of vaccines, therapeutic antibodies, and drugs. Using a mammalian cell expression system, we generated a recombinant fluorescent protein (Gamillus)-fused SARS-CoV-2 spike trimer (STG) to probe the viral entry process. In ACE2-expressing cells, we found that the STG probe has excellent performance in the live-cell visualization of receptor binding, cellular uptake, and intracellular trafficking of SARS-CoV-2 under virus-free conditions. The new system allows quantitative analyses of the inhibition potentials and detailed influence of COVID-19-convalescent human plasmas, neutralizing antibodies and compounds, providing a versatile tool for high-throughput screening and phenotypic characterization of SARS-CoV-2 entry inhibitors. This approach may also be adapted to develop a viral entry visualization system for other viruses.

Robust neutralization assay based on SARS-CoV-2 S-bearing vesicular stomatitis virus (VSV) pseudovirus and ACE2-overexpressed BHK21 cells

The global pandemic of Coronavirus disease 2019 (COVID-19) is a disaster for human society. A convenient and reliable in vitro neutralization assay is very important for the development of neutralizing antibodies, vaccines and other inhibitors. In this study, G protein-deficient vesicular stomatitis virus (VSVdG) bearing full-length and truncated spike (S) protein of SARS-CoV-2 were evaluated. The virus packaging efficiency of VSV-SARS-CoV-2-Sdel18 (S with C-terminal 18 amino acid truncation) is much higher than VSV-SARS-CoV-2-S. A neutralization assay for antibody screening and serum neutralizing titer quantification was established based on VSV-SARS-CoV-2-Sdel18 pseudovirus and human angiotensin-converting enzyme 2 (ACE2) overexpressed BHK21 cell (BHK21-hACE2). The experimental results can be obtained by automatically counting EGFP positive cell number at 12 hours after infection, making the assay convenient and high-throughput. The serum neutralizing titer of COVID-19 convalescent patients measured by VSV-SARS-CoV-2-Sdel18 pseudovirus assay has a good correlation with live SARS-CoV-2 assay. Seven neutralizing monoclonal antibodies targeting receptor binding domain (RBD) of SARS-CoV-2-S were obtained. This efficient and reliable pseudovirus assay model could facilitate the development of new drugs and vaccines.

Single-domain antibody - advances in research and application / 生物工程学报

Conventional IgG is composed of heavy and light chains. The light chain has one variable region (VL) and one constant region (CL) domain, whereas the heavy chain has one variable region (VH) and three constant region domains (CH1, CH2 and CH3). Single domain antibody (sdAb) is a kind of antibody that is composed of a variable domain of heavy chain and devoid of the light chain completely. Due to its small size, it is also called as nanobody. Although the sdAb has a simple structure, it can exhibit a comparable even better antigen-binding affinity than conventional antibody. Compared with conventional antibody, the small size, high stability and simplicity in recombinant expression are representative advantages of sdAb. In recent years, scientists are becoming increasingly interested in the roles of sdAb in fundamental biomedical research and clinical application. In this review, we summarized the structural features, physicochemical properties, screening strategies and recent advances in application of sdAb.