Recent advances and mechanisms of action of PD-L1 degraders as potential therapeutic agents.

PD-L1 is an important immune checkpoint protein that can bind to T cells' PD-1 receptor, thereby promoting immune escape from tumors. In recent years, many researchers have developed strategies to degrade PD-L1 to improve the effect of immunotherapy. The study of degrading PD-L1 provides new opportunities for immunotherapy. Here, we mainly summarize and review the current active molecules and mechanisms that mediate the degradation of immature and mature PD-L1 during the post-translational modification stages, involving PD-L1 phosphorylation, glycosylation, palmitoylation, ubiquitination, and the autophagy-lysosomal process. This review expects that by degrading PD-L1 protein, we will not only gain a better understanding of oncogenic mechanisms involving tumor PD-L1 protein but also provide a new way to improve immunotherapy.

Design, Synthesis, and Antitumor Activity Evaluation of 2-Arylmethoxy-4-(2,2'-dihalogen-substituted biphenyl-3-ylmethoxy) Benzylamine Derivatives as Potent PD-1/PD-L1 Inhibitors.

Novel 2-arylmethoxy-4-(2,2'-dihalogen-substituted biphenyl-3-ylmethoxy) benzylamine derivatives were designed, synthesized, and evaluated in vitro and in vivo against cancers as PD-1/PD-L1 inhibitors. Through the computer-aided structural optimization and the homogeneous time-resolved fluorescence (HTRF) assay, compound A56 was found to most strongly block the PD-1/PD-L1 interaction with an IC50 value of 2.4 ± 0.8 nM and showed the most potent activity. 1H NMR titration results indicated that A56 can tightly bind to the PD-L1 protein with KD < 1 µM. The X-ray diffraction data for the cocrystal structure of the A56/PD-L1 complex (3.5 Å) deciphered a novel binding mode in detail, which can account for its most potent inhibitory activity. Cell-based assays further demonstrated the strong ability of A56 as an hPD-1/hPD-L1 blocker. Especially in an hPD-L1 MC38 humanized mouse model, A56 significantly inhibited tumor growth without obvious toxicity, with a TGI rate of 55.20% (50 mg/kg, i.g.). In conclusion, A56 is a promising clinical candidate worthy of further development.

PD-L1 dimerisation induced by biphenyl derivatives mediates anti-breast cancer activity via the non-immune PD-L1-AKT-mTOR/Bcl2 pathway.

Recent studies on biphenyl-containing compounds, a type of PD-1/PD-L1 blocker which binds to PD-L1 and induces dimerisation, have focussed on its immune function. Herein, 10 novel biphenyl derivatives were designed and synthesised. The results of the CCK-8 showed that compounds have different anti-tumour activities for tumour cells in the absence of T cells. Particularly, 12j-4 can significantly induce the apoptosis of MDA-MB-231 cells (IC50 = 2.68 ± 0.27 µM). In further studies, 12j-4 has been shown to prevent the phosphorylation of AKT by binding to cytoplasmic PD-L1, which induces apoptosis in MDA-MB-231 cells through non-immune pathways. The inhibition of AKT phosphorylation restores the activity of GSK-3ß, ultimately resulting in the degradation of PD-L1. Besides, in vivo study indicated that 12j-4 repressed tumour growth in nude mice. As these biphenyls exert their anti-tumour effects mainly through non-immune pathways, they are worthy of further study as PD-L1 inhibitors.

Repurposing and discovery of transmembrane serine protease 2 (TMPRSS2) inhibitors as prophylactic therapies for new coronavirus disease 2019 (COVID-19).

The global pandemic of COVID-19 disease is caused by the pathogenic factor called SARS-CoV-2. Meanwhile, a series of vaccines and small-molecule drugs, including the mRNA vaccines and Paxlovid®, have been approved, but their efficacy is decreased significantly due to the constant emergence of mutant viral strains. The R&D of host-directed therapeutics has great potential to overcome such limitations and provide new prevention and therapy options for patients with COVID-19 or high-risk group for SARS-CoV-2 infections. Transmembrane serine protease 2 (TMPRSS2) is belonging to a protein family with highly conserved serine protease domain whose crucial role in viral entry is to activate the spike protein of viruses to induce the fusion between host cells and viruses. In this review, we sketch the critical position of TMPRSS2 in the SARS-CoV-2 viral entry and summarize the advanced research and development of TMPRSS2 inhibitors, including repurposed drugs, as a new way to fight COVID-19.

Design, synthesis and anti-tumor activity of novel benzothiophenonaphthalimide derivatives targeting mitochondrial DNA (mtDNA) G-quadruplex.

A series of new naphthalimide derivatives, benzothiophenonaphthalimides (7a-7g, 8a-8g), were designed and synthesized, of which compounds 8a-8g are hydrochloride salts of corresponding compounds 7a-7g. All compounds presented different anti-tumor activities for tumor cells tested by the CCK-8 assay. In particular, compound 7c displayed the strongest anti-tumor activity with an IC50 value of 0.59 ± 0.08 µM and the best selectivity for HepG2 cells. At the same time, it was observed that 7c could induce HepG2 cell apoptosis, hinder cancer cell migration and arrest the cell cycle at the G2/M phase. Further mechanism studies revealed that 7c selectively induced a G-rich HRCC DNA sequence in the mitochondria to form a G-quadruplex structure (G4) and stabilized it, which mediated the decrease in mitochondrial membrane potential and the production of reactive oxygen species, causing mitochondrial dysfunction. Finally, this led to proliferative inhibition and apoptosis of cancer cells and protective autophagy by promoting the expression of p-Erk1/2. The in vivo experimental results indicated that the compound 8c as a salt of 7c showed significant in vivo anti-tumor efficacy in the HepG2-xenograft mouse model with a tumor growth inhibition rate of 51.4% at a dose of 15 mg/kg. These results suggest that 7c possesses a different anti-tumor mechanism from the previous main reported mechanism of naphthalimide derivatives, which targets the nucleus. In brief, 7c has good anti-tumor activity in vitro and in vivo and may act as a leading compound in development of drugs against liver cancer.

Comparison of the effect of different degrees of passive leg raising on the internal jugular vein cross-sectional area in patients before thoracic surgery.

BACKGROUND: This study investigated the effect of different degrees of passive leg raising (PLR) on the internal jugular vein (IJV) cross-sectional area (CSA) and on the success rate of IJV cannulation in patients waiting for thoracic surgery, to analyze whether body mass index (BMI), gender, age, fasting time and preoperative rehydration have any impact on changes in the IJV CSA. METHODS: Eighty-two patients scheduled for selective thoracic surgery were enrolled in this study. Patients were randomly assigned based on a computer-generated randomization sequence into 3 groups: 0, 30, and 50 degrees (n = 32, 25, and 25 patients, respectively). The right IJV CSA in the sequence of 0-degree (supine position), 30-degree and 50-degree PLR positions was recorded in all patients using an ultrasound probe. The relationship of BMI, gender, age, fasting time and preoperative rehydration to the IJV CSA was analyzed. Then, each patient was returned to a supine position. After waiting for at least 5 min, patients were placed in a PLR position at 0, 30, or 50 degrees, and then IJV cannulation was performed without ultrasound guidance. The success rate of IJV catheterization at different PLR angles was compared. RESULTS: The average CSA of the right IJV in the supine position, 30-degree PLR position and 50-degree PLR position was 1.39 ± 0.63 cm2, 1.65 ± 0.73 cm2, and 1.68 ± 0.71 cm2, respectively. These results showed gradual increases in the IJV CSA of 18.5% (30-degree PLR) and 20.2% (50-degree PLR) when compared to that in the supine position (P = 0.045 and 0.025, respectively). However, only fasting time had a significant impact on the increase in the right IJV CSA at different PLR angles (P = 0.026). Other factors, such as BMI, gender, age and preoperative rehydration, had no significant effects. The success rates of IJV catheterization at angles of 0, 30 and 50 degrees were 84.3, 88 and 92%, respectively; however, there were no significant differences among the three groups (P = 0.674). CONCLUSIONS: PLR increases the CSA of the right IJV, especially for patients with long fasting times before thoracic surgery. The effect of the 30-degree PLR position is similar to that of the 50-degree PLR position. However, the success rate of right IJV catheterization was not enhanced in this study using landmark-guided puncture, even though the CSA of the right IJV was increased. TRIAL REGISTRATION: Clinical trial registration number: ChiCTR1800015051 . Date of registration: March 2018.