Immune checkpoint inhibitors in non-small-cell lung cancer: current status and future directions

The Prognostic Significance of PD1 and PDL1 Gene Expression in Lung Cancer: A Meta-Analysis

Background

Immune checkpoint blockade therapy represents an extraordinary advance in lung cancer treatment. It is important to determine the expression of immune checkpoint genes, such as programmed cell death 1 (PD1) and programmed cell death-ligand 1 (PDL1), to develop immunotherapeutic strategies. The aim of this study was to explore the association between PD1 and PDL1 gene expression and prognoses and outcomes in lung cancer.

Methods

This meta-analysis analyzed 1,251 patients from eight different microarray gene expression datasets and were evaluated for their prognostic implications and verified using another independent research.

Results

The mean expression levels of PDL1 in adenocarcinoma (AD) and squamous cell carcinoma (SC) were significantly higher in patients who died than in patients who did not. There was a trend toward incremental increases in PD1 and PDL1 expression significantly decreasing the risk of relapse and death among AD patients (HR = 0.69; 95% CI = 0.53 ~ 0.91; HR = 0.68; 95% CI = 0.54 ~ 0.84, respectively) and SC patients (HR = 0.53; 95% CI = 0.32 ~ 0.89; HR = 0.78; 95% CI = 0.57 ~ 1.00 respectively), as early-stage patients in this study were more likely to have high expression of both PD1 and PDL1 than late-stage patients (P-trend < 0.05). In contrast, late-stage SC patients expressing one or more of the genes at a high level had a significantly elevated risk of relapse (HR = 1.51; 95% CI = 1.07 ~ 2.11) and death (HR = 1.41; 95% CI = 1.08 ~ 1.84). This result was consistent with the validation data set.

Conclusion

These findings indicate that high expression of PD1 and PDL1 is associated with superior outcome in early-stage lung cancer but an adverse outcome in late-stage lung cancer. The expression levels of PD1 and PDL1 individually or jointly are potential prognostic factors for predicting patient outcomes in lung cancer.

Primary and Acquired Resistance to Immunotherapy in Lung Cancer: Unveiling the Mechanisms Underlying of Immune Checkpoint Blockade Therapy

After several decades without maintained responses or long-term survival of patients with lung cancer, novel therapies have emerged as a hopeful milestone in this research field. The appearance of immunotherapy, especially immune checkpoint inhibitors, has improved both the overall survival and quality of life of patients, many of whom are diagnosed late when classical treatments are ineffective. Despite these unprecedented results, a high percentage of patients do not respond initially to treatment or relapse after a period of response. This is due to resistance mechanisms, which require understanding in order to prevent them and develop strategies to overcome them and increase the number of patients who can benefit from immunotherapy. This review highlights the current knowledge of the mechanisms and their involvement in resistance to immunotherapy in lung cancer, such as aberrations in tumor neoantigen burden, effector T-cell infiltration in the tumor microenvironment (TME), epigenetic modulation, the transcriptional signature, signaling pathways, T-cell exhaustion, and the microbiome. Further research dissecting intratumor and host heterogeneity is necessary to provide answers regarding the immunotherapy response and develop more effective treatments for lung cancer.

Biomarkers for precision immunotherapy in the metastatic setting: hope or reality?

Precision immunotherapy is a crucial approach to improve the efficacy of anti-cancer treatments, particularly in the metastatic setting. In this respect, accurate patient selection takes advantage of the multidimensional integration of patients' clinical information and tumour-specific biomarkers status. Among these biomarkers, programmed death-ligand 1, tumour-infiltrating lymphocytes, microsatellite instability, mismatch repair and tumour mutational burden have been widely investigated. However, novel tumour-specific biomarkers and testing methods will further improve patients' outcomes. Here, we discuss the currently available strategies for the implementation of a precision immunotherapy approach in the clinical management of metastatic solid tumours and highlight future perspectives.

Main Strategies for the Identification of Neoantigens

Genetic instability of tumors leads to the appearance of numerous tumor-specific somatic mutations that could potentially result in the production of mutated peptides that are presented on the cell surface by the MHC molecules. Peptides of this kind are commonly called neoantigens. Their presence on the cell surface specifically distinguishes tumors from healthy tissues. This feature makes neoantigens a promising target for immunotherapy. The rapid evolution of high-throughput genomics and proteomics makes it possible to implement these techniques in clinical practice. In particular, they provide useful tools for the investigation of neoantigens. The most valuable genomic approach to this problem is whole-exome sequencing coupled with RNA-seq. High-throughput mass-spectrometry is another option for direct identification of MHC-bound peptides, which is capable of revealing the entire MHC-bound peptidome. Finally, structure-based predictions could significantly improve the understanding of physicochemical and structural features that affect the immunogenicity of peptides. The development of pipelines combining such tools could improve the accuracy of the peptide selection process and decrease the required time. Here we present a review of the main existing approaches to investigating the neoantigens and suggest a possible ideal pipeline that takes into account all modern trends in the context of neoantigen discovery.

Non-small cell lung carcinomas with a minor sarcomatoid component and pleomorphic carcinomas are associated with high expression of programmed death ligand 1

Pleomorphic carcinomas are known to be highly programmed death ligand 1 (PD-L1) positive non-small cell lung cancer (NSCLC) types. However, the level of PD-L1 expression in lung carcinomas with a minor sarcomatoid component, comprising less than 10 % of the tumor mass, has not been determined yet. We hypothesized that NSCLC with a minor sarcomatoid component is more closely related to pleomorphic carcinomas in terms of PD-L1 expression than to NSCLC types without sarcomatoid features. The surgical resections from 690 lung carcinoma patients were retrospectively analyzed for the presence of PD-L1 by means of immunohistochemistry using the 22C3 PharmDx assay. The tumor proportion score system was applied to quantify the level of PD-L1 expression. Membranous staining present in ≥ 1 % of tumor cells was chosen as the cut-off to define a positive result for PD-L1 expression. Tumors were allocated into one of four subgroups: "adenocarcinoma", "squamous cell carcinoma", "pleomorphic carcinoma", or "NSCLC with a minor sarcomatoid component". PD-L1 expression in pleomorphic carcinomas (26/32, 81.3 %) and in the subgroup of NSCLC with a minor sarcomatoid component (35/46, 76.1 %) was identified in a comparable proportion of cases. Pleomorphic carcinomas were significantly more often PD-L1 positive than adenocarcinomas (p < 0.001) or squamous cell carcinomas (p = 0.0015). Accordingly, the proportion of PD-L1 expressing NSCLC with a minor sarcomatoid component was significantly higher than that of the adenocarcinoma (p < 0.001) or squamous cell carcinoma (p = 0.002) subgroup. In summary, we identified a presumable new subgroup of highly PD-L1 positive neoplasms within the NSCLC spectrum that is related to pleomorphic carcinomas in terms of PD-L1 expression. Further investigation regarding genetic relation and mechanism of PD-L1 expression in these two NSCLC categories is recommended.

Nab-paclitaxel in combination with Bevacizumab in patients with non-squamous non-small cell lung cancer after failure of at least one prior systemic regimen

Background: Most patients with non-small cell lung cancer (NSCLC) experience disease progression after first-line treatment. The efficacy and safety of the nab-paclitaxel (nab-PTX) and bevacizumab combination as the second or further line of treatment in patients with advanced NSCLC have not been reported yet. Objective: To evaluate the efficacy and safety of the nab-PTX and bevacizumab combination in patients with advanced non-squamous (NSQ) NSCLC after failure of at least one prior systemic regimen. Methods: Patients with advanced (stage IV) NSQ NSCLC who received the nab-PTX and bevacizumab combination as the second or further line treatment between February 2012 and December 2018 at the Cancer Hospital of the Chinese Academy of Medical Sciences (Beijing, China) were included in this retrospective study. The main outcomes included the objective response rate (ORR), progression-free survival (PFS), overall survival (OS), and safety. Results: Thirty-four patients received 1-27 cycles (median, four cycles) of treatment; 67.6% (23/34) patients had undergone at least two lines of previous treatment. The ORR and disease control rates were 26.5% (9/34) and 82.4% (28/34), respectively. The median PFS and OS were 6.0 (95% CI=2.9-7.2) and 11.0 (95% CI=7.8-18.7) months, respectively. The multivariable analyses indicated that the combined use of other drugs and pleural metastasis were respectively associated with better PFS (hazard ratio=0.354, 95% CI=0.134-0.935, P=0.036) and OS (hazard ratio=0.540, 95% CI=0.118-0.980, P=0.046). The most frequent grade 3-4 adverse events (AEs) were neutropenia 20.6% (7/34), leukopenia 8.8% (3/34), and anemia 5.9% (2/34). No grade 5 AE occurred. Conclusion: Combined nab-PTX and bevacizumab might be an effective treatment regimen for patients with advanced NSQ NSCLC after failure of at least one prior systemic regimen, but studies have to validate those findings.

Impact of performance status on non-small-cell lung cancer patients with a PD-L1 tumour proportion score ≥50% treated with front-line pembrolizumab

Objectives: We retrospectively analysed patients with advanced non-small-cell lung cancer (NSCLC) harbouring high PD-L1 expression (>50%) and treated with front-line pembrolizumab, comparing outcomes of patients with an Eastern Cooperative Oncology Group (ECOG) performance status (PS) 2 to those with PS 0-1.Methods: Data were collected by 16 participating centres. All patients with NSCLC and high PD-L1, treated with first-line pembrolizumab were included. We collected medical data from patient files, pathology and laboratory reports. Patient characteristics, comorbidities, PS, and tumour characteristics were reported. Overall survival (OS), progression-free survival (PFS) and response rate (RR) were calculated.Results: 302 patients were included, 246 with PS 0-1, 56 with PS 2. RR was 72% among patients with PS 0-1 compared to 45% with PS2 (odds ratio (OR) 0.31 (95% CI: 0.17-0.57), p < .001). Median PFS was 2.6 months (95% CI: 1.9-5.1) among patients with PS2 and 11.3 months (95% CI: 8.5-14.4) among those with PS 0-1. Median OS was 7.8 months (95% CI: 2.5-10.7) in the PS2 group, not reached in the PS 0-1 group. PS 2 remained predictive of poor outcomes in multivariate analysis.Conclusion: PS 2 is a strong independent predictor of poor response and survival in NSCLC patients with high PD-L1, treated with front-line pembrolizumab. Prospective randomised trials comparing immunotherapy to chemotherapy in this population would be welcome.

Induction of cytoprotective autophagy by morusin via AMP-activated protein kinase activation in human non-small cell lung cancer cells

BACKGROUND/OBJECTIVES

Morusin, a marker component of Morus alba L., possesses anti-cancer activity. The objective of this study was to determine autophagy-inducing effect of morusin in non-small cell lung cancer (NSCLC) cells and investigate the underlying mechanism.

SUBJECTS/METHODS

Autophagy induction and the expression of autophagy-related proteins were analyzed by LC3 immunofluorescence and western blot, respectively. The role of autophagy and AMP-activated protein kinase (AMPK) was determined by treating NSCLC cells with bafilomycin A1, an autophagy inhibitor, and compound C, an AMPK inhibitor. Cytotoxicity and apoptosis induction were determined by MTT assay, trypan blue exclusion assay, annexin V-propidium iodide (PI) double staining assay, and cell cycle analysis.

RESULTS

Morusin increased the formation of LC3 puncta in the cytoplasm and upregulated the expression of autophagy-related 5 (Atg5), Atg12, beclin-1, and LC3II in NSCLC cells, demonstrating that morusin could induce autophagy. Treatment with bafilomycin A1 markedly reduced cell viability but increased proportions of sub-G1 phase cells and annexin V-positive cells in H460 cells. These results indicate that morusin can trigger autophagy in NSCLC cells as a defense mechanism against morusin-induced apoptosis. Furthermore, we found that AMPK and its downstream acetyl-CoA carboxylase (ACC) were phosphorylated, while mammalian target of rapamycin (mTOR) and its downstream p70S6 kinase (p70S6K) were dephosphorylated by morusin. Morusin-induced apoptosis was significantly increased by treatment with compound C in H460 cells. These results suggest that morusin-induced AMPK activation could protect NSCLC cells from apoptosis probably by inducing autophagy.

CONCLUSIONS

Our findings suggest that combination treatment with morusin and autophagy inhibitor or AMPK inhibitor might enhance the clinical efficacy of morusin for NSCLC.

Programmed death ligand 1 protein expression, histological tumour differentiation and intratumoural heterogeneity in pulmonary adenocarcinoma

Intratumoural heterogeneity of pulmonary adenocarcinoma challenges the accurate interpretation of programmed death ligand 1 (PD-L1) immunohistochemistry, which is the only validated predictive marker for successful anti-PD-1/PD-L1 immunotherapy. The aim of this study was to determine whether PD-L1 expression is related to adenocarcinoma histological differentiation in a retrospective analysis of tumour biopsies with intratumoural histological heterogeneity. Adenocarcinomas with high intratumoural heterogeneity were categorised as 'mixed adenocarcinomas'. PD-L1 expression was determined immunohistochemically using tumour proportion scores (TPS). In 'mixed adenocarcinomas' PD-L1 scores were assessed across tumour areas with specific histological patterns. Comparisons were performed between histologically distinct differentiated tumours and/or histological areas. Poorly differentiated adenocarcinomas, represented by predominantly solid or micropapillary histological patterns, showed significantly higher expression of PD-L1 than other subtypes (p<0.001). Differentiation of intra-adenocarcinoma components was inversely correlated with PD-L1 expression: there were more PD-L1 positive cells in poorly differentiated areas than less differentiated (p<0.001), or than well differentiated areas (p<0.001), and in less differentiated more than well differentiated areas (p=0.001). In conclusion, PD-L1 expression is associated with poorly differentiated morphology in adenocarcinomas with intratumoural histological heterogeneity. Consequently, a TPS approach may not account for the contribution of more aggressive tumour components with higher levels of PD-L1 expression in within the tumour. Performing spectral analyses of PD-L1 expression across tumours is likely to be more accurate.

Fluoropyrimidine Modulation of the Anti-Tumor Immune Response-Prospects for Improved Colorectal Cancer Treatment

Chemotherapy modulates the anti-tumor immune response and outcomes depend on the balance of favorable and unfavorable effects of drugs on anti-tumor immunity. 5-Florouracil (5-FU) is widely used in adjuvant chemotherapy regimens to treat colorectal cancer (CRC) and provides a survival benefit. However, survival remains poor for CRC patients with advanced and metastatic disease and immune checkpoint blockade therapy benefits only a sub-set of CRC patients. Here we discuss the effects of 5-FU-based chemotherapy regimens to the anti-tumor immune response. We consider how different aspects of 5-FU's multi-factorial mechanism differentially affect malignant and immune cell populations. We summarize recent studies with polymeric fluoropyrimidines (e.g., F10, CF10) that enhance DNA-directed effects and discuss how such approaches may be used to enhance the anti-tumor immune response and improve outcomes.

Protein kinase C-iota-mediated glycolysis promotes non-small-cell lung cancer progression

Purpose

To determine whether protein kinase C-iota (PKC-iota) is associated with glucose metabolism in non-small-cell lung cancer (NSCLC) and whether its regulatory effect on metabolic and biological changes observed in NSCLC can be mediated by glucose transporter 1 (GLUT1).

Patients and methods

Forty-five NSCLC patients underwent combined ¹⁸F-fludeoxyglucose (¹⁸F-FDG) positron emission tomography and computed tomography (PET/CT) before surgery, and another eighty-one NSCLC patients were followed-up for 1–91 months after tumor resection. The rate of glucose metabolism in NSCLC was quantified by measuring the maximum standardized uptake value (SUVmax) by ¹⁸F-FDG PET/CT. PKC-iota and GLUT1 in NSCLC were detected by immunostaining. In vitro, PKC-iota was knocked down, whereas GLUT1 was silenced with or without PKC-iota overexpression to identify the role of PKC-iota in glycolysis. Spearman’s rank correlation coefficient was used in the correlation analysis. Kaplan-Meier analysis was used to assess survival duration.

Results

There was a positive relationship between PKC-iota expression and SUVmax in NSCLC (r=0.649, P<0.001). PKC-iota expression also showed a positive relationship with GLUT1 in NSCLC tissues (r=0.686, P<0.001). Patients whose NSCLC tissues highly co-expressed PKC-iota and GLUT1 had worse prognosis compared with patients without high co-expression of PKC-iota and GLUT1. In vitro, PKC-iota silencing significantly decreased the expression of GLUT1 and inhibited glucose uptake and glycolysis; c-Myc silencing restrained PKC-iota-mediated GLUT1 elevation; GLUT1 knockdown remarkably suppressed PKC-iota-mediated glycolysis and cell growth.

Conclusion

In NSCLC, the rate of glucose metabolism was positively correlated with PKC-iota expression. PKC-iota increased glucose accumulation and glycolysis by upregulating c-Myc/GLUT1 signaling and is thus involved in tumor progression.