A systematic review of phase II trials exploring anti-PD-1/PD-L1 combinations in patients with solid tumors

PD-1: A critical player and target for immune normalization

Immune system imbalances contribute to the pathogenesis of several different diseases, and immunotherapy shows great therapeutic efficacy against tumours and infectious diseases with immune-mediated derivations. In recent years, molecules targeting the programmed cell death protein 1 (PD-1) immune checkpoint have attracted much attention, and related signalling pathways have been studied clearly. At present, several inhibitors and antibodies targeting PD-1 have been utilized as anti-tumour therapies. However, increasing evidence indicates that PD-1 blockade also has different degrees of adverse side effects, and these new explorations into the therapeutic safety of PD-1 inhibitors contribute to the emerging concept that immune normalization, rather than immune enhancement, is the ultimate goal of disease treatment. In this review, we summarize recent advancements in PD-1 research with regard to immune normalization and targeted therapy.

The relationship between autophagy and PD-L1 and their role in antitumor therapy

Immune checkpoint blockade therapy is an important advance in cancer treatment, and the representative drugs (PD-1/PD-L1 antibodies) have greatly improved clinical outcomes in various human cancers. However, since many patients still experience primary resistance, they do not respond to anti-PD1/PD-L1 therapy, and some responders also develop acquired resistance after an initial response. Therefore, combined therapy with anti-PD-1/PD-L1 immunotherapy may result in better efficacy than monotherapy. In tumorigenesis and tumor development processes, the mutual regulation of autophagy and tumor immune escape is an intrinsic factor of malignant tumor progression. Understanding the correlation between the tumor autophagy pathway and tumor immune escape may help identify new clinical cancer treatment strategies. Since both autophagy and immune escape of tumor cells occur in a relatively complex microenvironmental network, autophagy affects the immune-mediated killing of tumor cells and immune escape. Therefore, comprehensive treatment targeting autophagy and immune escape to achieve “immune normalization” may be an important direction for future research and development. The PD-1/PD-L1 pathway is essential in tumor immunotherapy. High expression of PD-L1 in different tumors is closely related to poor survival rates, prognoses, and treatment effects. Therefore, exploring the mechanism of PD-L1 expression is crucial to improve the efficacy of tumor immunotherapy. Here, we summarize the mechanism and mutual relationship between autophagy and PD-L1 in antitumor therapy, which may help enhance current antitumor immunotherapy approaches.

Resveratrol analog, triacetylresveratrol, a potential immunomodulator of lung adenocarcinoma immunotherapy combination therapies

Introduction

Resveratrol, an activator for longevity regulatory genes-sirtuin family (SIRTs) and Sirtuin 2 (SIRT2) is an important factor of SIRTs which demonstrated biological function in cancers, but the underlying mechanism is unrevealed.

Methods

We investigated the mRNA and protein levels of SIRT2 in a variety of cancers and the potential role for clinical prognosis, as well as analysed the association between the gene and immune infiltration in various cancers. And an analysis of two types of lung cancer was conducted to construct a systematic prognostic landscape. Finally, putative binding site of the triacetylresveratrol bound to SIRT2 was built from homology modeling.

Results and discussion

We concluded that higher mRNA and protein levels of SIRT2 affected prognosis in various types of cancers, especially in LUAD cohorts. In addition, SIRT2 is linked with a better overall survival (OS) in LUAD patients. Further research suggested a possible explanation for this phenotype might be that SIRT2 mRNA levels are positively correlated with infiltrating status of multiple immunocytes in LU-AD but not LUSC, i.e. SIRT2 expression may contribute to the recruitment of CD8+T cell, CD4+ T cell, T cell CD4+ memory resting, Tregs, T cell NK and positively correlated to the expression of PD-1, also excluding neutrophil, T cell CD8+ naïve and B cell plasma cells in LUAD. We found that triacetyl-resveratrol demonstrated the most potent agonist efficiency to SIRT2 and the EC 50 as low as 142.79 nM. As a result, SIRT2 appears to be a promising novel biomarker for prognosis prediction in patients with LUAD and triacetylresveratrol might be a potential immunomodulator of LUAD to anti-PD-1 based immunotherapy combination therapies.

Recent Trends in Diagnostic Biomarkers of Tumor Microenvironment

The tumor microenvironment (TME) play critical roles in tumor survival, progression, and metastasis and can be considered potential targets for molecular imaging of cancer. The targeting agents for imaging of TME components (e.g., fibroblasts, mesenchymal stromal cells, immune cells, extracellular matrix, blood vessels) provide a promising strategy to target these biomarkers for the early diagnosis of cancers. Moreover, various cancer types have similar tumor immune microenvironment (TIME) features that targeting those biomarkers and offer clinically translatable molecular imaging of cancers. In this review, we categorize and summarize the components in TME which have been targeted for molecular imaging. Moreover, this review updated the recent progress in targeted imaging of TIME biological molecules by various modalities for the early detection of cancer.

Analysis of the Role and Mechanism of ZEB1 in Regulating Cervical Carcinoma Progression via Modulating PD-1/PD-L1 Checkpoint

Background

Cervical carcinoma (CC) is a common and highly malignant tumor in women. The involvement of zinc finger E-box binding homeobox 1 (ZEB1) in many kinds of tumors has been well-documented; however, its role and mechanism in CC remain to be clarified.

Objective

This study investigated the mechanism of ZEB1 in modulating the growth and metastasis of CC cells.

Methods

The expression of ZEB1 in CC tissues and adjacent normal counterparts was determined by reverse transcription-polymerase chain reaction (RT-PCR). The correlation between ZEB1 and patient clinicopathological indexes was analyzed. In vitro, gain and loss functions of ZEB1 were performed in C-33A and HeLa cell lines. The proliferation, migration, and invasion of CC cells were detected by Cell Counting Kit-8 (CCK-8) assay and transwell assay, respectively. The expression levels of apoptosis-related proteins such as BCL2-associated X (Bax), B-cell lymphoma-2 (Bcl2), and Caspase-3, as well as epithelial-mesenchymal transition (EMT)-associated proteins including E-cadherin, Vimentin, and Snail, were measured by Western blotting. In addition, the targeting relationship between ZEB1 and programmed death 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) was predicted by bioinformatics and further verified by dual-luciferase reporter assay.

Results

ZEB1 was significantly up-regulated in CC tissues compared with normal counterparts. ZEB1 overexpression promoted the migration, proliferation, and invasion of CC cells and inhibited apoptosis, while knocking down ZEB1 contributed to the opposite effects. In addition, experiments on related mechanisms confirmed that ZEB1 targeted the 3'EUTR terminal of PD-1/PD-L1 and negatively regulated its expression. And an interaction between ZEB1 and PD-1/PD-L1 was identified.

Conclusion

ZEB1 can promote the proliferation and metastasis of CC cells via modulating the PD-1/PD-L1 checkpoint.