[Advances of PD-1/PD-L1 signaling pathway in immune escape and treatment for non-small cell lung cancer]

The promising immune checkpoint LAG-3 in cancer immunotherapy: from basic research to clinical application

LAG-3, a type of immune checkpoint receptor protein belonging to the immunoglobulin superfamily, is confirmed to be expressed on activated immune cells, mainly including activated T cells. LAG-3 can negatively regulate the function of T cells, exerting important effects on maintaining the homeostasis of the immune system under normal physiological conditions and promoting tumor cells immune escape in the tumor microenvironment. Given its important biological roles, LAG-3 has been regarded as a promising target for cancer immunotherapy. To date, many LAG-3 inhibitors have been reported, which can be divided into monoclonal antibody, double antibody, and small molecule drug, some of which have entered the clinical research stage. LAG-3 inhibitors can negatively regulate and suppress T cell proliferation and activation through combination with MHC II ligand. Besides, LAG-3 inhibitors can also affect T cell function via binding to Galectin-3 and LSECtin. In addition, LAG-3 inhibitors can prevent the FGL1-LAG-3 interaction, thereby enhancing the human body’s antitumor immune effect. In this review, we will describe the function of LAG-3 and summarize the latest LAG-3 inhibitors in the clinic for cancer therapy.

PD-L1 Expression Level Displays a Positive Correlation with Immune Response in Pancreatic Cancer

The expression of PD-L1 could be a novel biomarker which predicts that patients are more likely to respond to immunotherapy. Our study investigated the relationship among clinicopathological characteristics, prognosis, PD-L1 expression levels, and FOXP3⁺ Treg infiltration. In addition, the relationship among clinicopathological characteristics, prognosis, PD-L1 expression levels, and FOXP3⁺ Treg infiltration was explored. Furthermore, the relationship between PD-L1 expression and FOXP3⁺ Treg infiltration was examined. We found that 41.3% of pancreatic cancer patients had PD-L1-positive staining; both PD-L1 expression levels and FOXP3⁺ Treg infiltration were significantly associated with depth of invasion, lymph node metastasis, distant metastasis, and pTNM. In addition, PD-L1 expression and FOXP3⁺ Treg infiltration also could be prognostic biomarkers for pancreatic cancer.

The effect of PD-L1/PD-1 immunotherapy in the treatment of squamous non-small-cell lung cancer: a meta-analysis of randomized controlled clinical trials

Background

This meta-analysis evaluated the efficacy of PD-L1/PD-1 immunotherapy compared with chemotherapy in IIIB or IV or recurrent squamous non-small cell lung cancer (NSCLC) patients.

Methods

We performed a literature search on the PubMed, EMBASE, Web of Science, and Cochrane databases, in addition to the abstracts from major conference proceedings of the European Society for Medical Oncology (ESMO), the American Society of Clinical Oncology (ASCO), and the World Conference on Lung Cancer (WCLC) from 2004 to May 2019. Randomized controlled trials that compared PD-L1/PD-1 immunotherapy with chemotherapy in IIIB or IV or recurrent squamous NSCLC were included. The endpoints were overall survival (OS), progression-free survival (PFS), objective response rate (ORR), disease control rate (DCR), 1-y OS rate, and 1-y PFS rate.

Results

A total of 3,213 IIIB or IV or recurrent squamous NSCLC patients from 12 trials of high quality were included in this meta-analysis, among whom 1,677 were in the PD-L1/PD-1 immunotherapy group and 1,536 were in the chemotherapy group. The results indicated that compared with chemotherapy, immunotherapy significantly prolonged OS (HR =0.75; 95% CI, 0.68-0.83; P<0.001) and PFS (HR =0.66; 95% CI, 0.60-0.73; P<0.001) in patients with advanced squamous NSCLC. The pooled model showed that ORR, DCR, and 1-y PFS rate were also significantly higher with immunotherapy compared with chemotherapy (ORR: RR =1.43; 95% CI, 1.11-1.83; P=0.005; DCR: RR =1.14; 95% CI, 1.05-1.24; P=0.003; 1-y PFS rate: RR =2.30; 95% CI, 1.69-3.13; P<0.001). The 1-y OS rate tended to be higher in the immunotherapy group, but there was no significant difference compared with chemotherapy (RR =1.28; 95% CI, 0.95-1.72; P=0.104).

Conclusions

Our study proves that PD-L1/PD-1 immunotherapy can significantly improve OS, PFS, ORR, DCR, and 1-y PFS of metastatic squamous NSCLC patients compared with chemotherapy.

Comparison of Different Antibody Clones for Immunohistochemistry Detection of Programmed Cell Death Ligand 1 (PD-L1) on Non-Small Cell Lung Carcinoma

Programmed cell death ligand 1 (PD-L1) is a major immune checkpoint protein that mediates antitumor immune suppression and response. Preliminary data suggest that its detection using immunohistochemistry (IHC) in formalin-fixed and paraffin-embedded tissues may predict clinical response to PD-1/PD-L1 therapy. In diagnostic pathology, it is essential to count with a validated IHC that can reliably detect PD-L1-positive cases. The present study was conducted to compare and validate different PD-L1 commercial clones and identify which ones can be reliably used by surgical pathologist to detect PD-L1 expression in human cancer tissues. Eight commercial available PD-L1 clones were tested and compared with a noncommercial PD-L1 antibody clone 5H1. Western blot and IHC using cell lines and human tissues were used to validate these clones. From all PD-L1 antibodies, only the clones E1L3N, E1J2J, SP142, 28-8, 22C3, and SP263 passed the Western blot and IHC validation, providing similar pattern than the clone 5H1 and then they were tested in 259 non–small cell lung cancer cases placed in 9 tissue microarrays. Among all cases, only those with ≥2 cores were included (185 cases). Positive and significant correlation was found between the median PD-L1 H-score in tumor and stroma compartments, for all selected antibodies. Overall, 56 of 185 cases were detected as positive cases in malignant cells expressing membranous PD-L1 by all the clones. However, the clone SP263 identified more PD-L1-positive cases compared with the other clones. Our results show that clones E1L3N, E1J2J, SP142, 28-8, 22C3, and SP263 provide positive membrane staining pattern comparable with clone 5H1. These commercial clones are comparable, but a careful evaluation by the pathologist is necessary to minimize error of positive misinterpretations.

Quantitative and qualitative characterization of Two PD-L1 clones: SP263 and E1L3N

BACKGROUND

Programmed Death Ligand 1 (PD-L1) is an immune modulating protein expressed on the surface of various inflammatory cells, including T Cells, B Cells, dendritic cells, and macrophages. PD-L1 represents an important diagnostic target; expression of PD-L1 on the surface of tumor cells, or within tumor-associated immune cells, is an important predictor of likely response to targeted therapies. In this study, we describe the optimization of immunohistochemistry (IHC) assays using two PD-L1 antibodies (SP263 and E1L3N) and compare the performance of the optimized assays.

METHODS

Fully automated immunohistochemical assays were optimized for the VENTANA PD-L1 (SP263) Rabbit Monoclonal Antibody and the PD-L1 (E1L3N®) XP® Rabbit mAb using instruments and detection chemistries from Ventana Medical Systems, Inc. ("SP263 assay" and "E1L3N assay," respectively). Tissue microarrays (TMAs) containing formalin fixed paraffin embedded (FFPE) non-small cell lung cancer (NSCLC) cases were used for the optimization and comparison staining. H scores were used for membrane scoring whereas percent positivity was used for tumor-associated immune cell scoring.

RESULTS

One-hundred NSCLC TMA case cores each stained with the SP263 and E1L3N assays were evaluated by two pathologists in a blinded study. Analysis of these specimens showed that the SP263 assay was more sensitive and had a wider dynamic range than the E1L3N assay. For sensitivity, many cases were found to be negative for membrane staining with the E1L3N assay, but had measurable staining with the SP263 assay. Dynamic range was demonstrated by the SP263 assay having well-distributed H scores while the E1L3N assay had a significantly higher proportion of cases clustered in the lowest H score bins. For tumor-associated immune cell staining, the two assays identified similar amounts of cells staining in each case, but the SP263 assay gave overall darker staining.

CONCLUSION

Since PD-L1 status is important for targeted therapies, having a specific and accurate diagnostic test is crucial for identifying patients who could benefit from these treatments. Due to its staining intensity, scoring range, and pathologist preference, the SP263 IHC assay has been deemed superior to the E1L3N IHC assay. Future clinical utility remains to be determined.