Overcoming resistance to PD-1/PD-L1 inhibitors in esophageal cancer

Current landscape of immunotherapy in esophageal cancer: a literature review

Background and Objective

Esophageal cancer has witnessed a significant shift in its epidemiology within the United States. Adenocarcinoma of the esophagus is now the fastest-growing solid malignancy, surpassing esophageal squamous cell carcinoma (ESCC) in frequency. There has been a concentrated effort to establish new therapies for dealing with this malignancy including immunotherapy in conjunction with surgery and radiotherapy. Our objective is to provide a comprehensive review of the current therapeutic strategies for esophageal cancer, with a particular focus on the emerging role of immunotherapy in combination with surgery and radiotherapy, and its impact on treatment outcomes.

Methods

A thorough search was done using keywords of "esophageal cancer", "immunotherapy in esophageal cancer", and "immunotherapy" in PubMed, MEDLINE, and Google Scholar databases. All studies that were identified in this search were analyzed for relevance and content.

Key Content and Findings

A total of 1,555 studies were identified which were checked for relevance and content. Fifteen articles were reviewed which focused on esophageal cancer and the immunotherapy directed towards this condition. This review article summarizes the most recent and available evidence on immunotherapy directed towards the treatment of esophageal cancer.

Conclusions

Esophageal cancer treatment is undergoing a paradigm shift with the advent of immunotherapy, particularly programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) inhibitors. These therapies hold promise for both second-line and first-line settings, with evolving biomarkers guiding treatment decisions. Combination strategies and personalized approaches are actively investigated to overcome resistance mechanisms and enhance treatment outcomes in this challenging cancer type.

Current status of research on the mechanisms of tumor-associated macrophages in esophageal cancer progression

Esophageal carcinoma (EC) is one of the most common tumors in China and seriously affects patient survival and quality of life. In recent years, increasing studies have shown that the tumor microenvironment is crucial in promoting tumor progression and metastasis. Tumor-associated macrophages (TAM) are key components of the tumor immune microenvironment and promote both tumor growth and antitumor immunity. Much evidence suggests that TAMs are closely associated with esophageal tumors. However, understanding of the clinical value and mechanism of action of TAM in esophageal cancer remains limited. Therefore, we reviewed the status of research on the role and mechanism of action of TAM in EC progression and summarized its potential clinical application value to provide a theoretical basis for the clinical treatment of EC.

GPCRs: emerging targets for novel T cell immune checkpoint therapy

Although immune checkpoint blockade (ICB) has become the mainstay of treatment for advanced solid organ malignancies, success in revitalizing the host anticancer immune response remains limited. G-protein coupled receptors (GPCRs) are a broad family of cell-surface proteins that have been regarded as main players in regulating the immune system, namely by mediating the activity of T lymphocytes. Among the most novel immunoregulatory GPCRs include GPR171, lysophosphatidic acid receptors (LPARs), GPR68, cannabinoid receptor 2 (CB2), and prostaglandin E receptors, many of which have shown promise in mediating antitumor response via activation of cytotoxic T cells, inhibiting immunosuppressive lymphocytes, and facilitating immune cell infiltration within the tumor microenvironment across multiple types of cancers. This paper reviews our current understanding of some of the most novel GPCRs-their expression patterns, evolving roles within the immune system and cancer, potential therapeutic applications, and perspective for future investigation.

Shedding Light on the Role of Exosomal PD-L1 (ExoPD-L1) in Cancer Progression: an Update

Exosomes are the primary category of extracellular vesicles (EVs), which are lipid-bilayer vesicles with biological activity spontaneously secreted from either normal or tansformed cells. They serve a crucial role for intercellular communication and affect extracellular environment and the immune system. Tumor-derived exosomes (TEXs) enclose high levels of immunosuppressive proteins, including programmed death-ligand 1 (PD-L1). PD-L1 and its receptor PD-1 act as crucial immune checkpoint molecules, thus facilitating tumor advancement by inhibiting immune responses. PDL-1 is abundantly present on tumor cells and interacts with PD-1 on activated T cells, resulting in T cell suppression and allowing immune evasion of cancer cells. Various FDA-approved monoclonal antibodies inhibiting the PD-1/PD-L1 interaction are commonly used to treat a diverse range of tumors. Although the achieved results are significant, some individuals have a poor reaction to PD-1/PD-L1 blocking. PD-L1-enriched TEXs may mimic the impact of cell-surface PD-L1, consequently potentiating tumor resistance to PD1/PD-L1 based therapy. In light of this, a strong correlation between circulating exosomal PD-L1 levels and response rate to anti-PD-1/PD-L1 antibody treatment has been evinced. This article inspects the function of exosomal PDL-1 in developing resistance to anti-PD-1/PD-L1 therapy for opening new avenues for overcoming tumor resistance to such modalities and development of more favored combination therapy.

ALKBH5 promotes non-small cell lung cancer progression and susceptibility to anti-PD-L1 therapy by modulating interactions between tumor and macrophages

BACKGROUND

Understanding the mechanisms that mediate the interaction between tumor and immune cells may provide therapeutic benefit to patients with cancer. The N6-methyladenosine (m6A) demethylase, ALKBH5 (alkB homolog 5), is overexpressed in non-small cell lung cancer. However, its role in the tumor microenvironment is unknown.

METHODS

Datasets and tissue samples were used to determine the relationship between ALKBH5 expression and immunotherapy efficacy. Bioinformatic analysis, colorimetric assay to determine m6A RNA methylation, dual luciferase reporter assay, RNA/m6A-modified RNA immunoprecipitation, RNA stability assay, and RNA sequencing were used to investigate the regulatory mechanism of ALKBH5 in non-small cell lung cancer. In vitro and in vivo assays were performed to determine the contribution of ALKBH5 to the development of non-small cell lung cancer.

RESULTS

ALKBH5 was upregulated in primary non-small cell lung cancer tissues. ALKBH5 was positively correlated with programmed death-ligand 1 expression and macrophage infiltration and was associated with immunotherapy response. JAK2 was identified as a target of ALKBH5-mediated m6A modification, which activates the JAK2/p-STAT3 pathway to promote non-small cell lung cancer progression. ALKBH5 was found to recruit programmed death-ligand 1-positive tumor-associated macrophages and promote M2 macrophage polarization by inducing the secretion of CCL2 and CXCL10. ALKBH5 and tumor-associated macrophage-secreted IL-6 showed a synergistic effect to activate the JAK2/p-STAT3 pathway in cancer cells.

CONCLUSIONS

ALKBH5 promotes non-small cell lung cancer progression by regulating cancer and tumor-associated macrophage behavior through the JAK2/p-STAT3 pathway and the expression of CCL2 and CXCL10, respectively. These findings suggest that targeting ALKBH5 is a promising strategy of enhancing the anti-tumor immune response in patients with NSCLC and that identifying ALKBH5 status could facilitate prediction of clinical response to anti-PD-L1 immunotherapy.

Mechanisms of tumor immunosuppressive microenvironment formation in esophageal cancer

As a highly invasive malignancy, esophageal cancer (EC) is a global health issue, and was the eighth most prevalent cancer and the sixth leading cause of cancer-related death worldwide in 2020. Due to its highly immunogenic nature, emer-ging immunotherapy approaches, such as immune checkpoint blockade, have demonstrated promising efficacy in treating EC; however, certain limitations and challenges still exist. In addition, tumors may exhibit primary or acquired resistance to immunotherapy in the tumor immune microenvironment (TIME); thus, understanding the TIME is urgent and crucial, especially given the im-portance of an immunosuppressive microenvironment in tumor progression. The aim of this review was to better elucidate the mechanisms of the suppressive TIME, including cell infiltration, immune cell subsets, cytokines and signaling pathways in the tumor microenvironment of EC patients, as well as the downregulated expression of major histocompatibility complex molecules in tumor cells, to obtain a better understanding of the differences in EC patient responses to immunotherapeutic strategies and accurately predict the efficacy of immunotherapies. Therefore, personalized treatments could be developed to maximize the advantages of immunotherapy.

A new era in cancer treatment: harnessing ZIF-8 nanoparticles for PD-1 inhibitor delivery

This review delves into the potential of zeolitic imidazolate framework-8 (ZIF-8) nanoparticles in augmenting the efficacy of cancer immunotherapy, with a special focus on the delivery of programmed cell death receptor 1 (PD-1) inhibitors. The multifunctional nature of ZIF-8 nanoparticles as drug carriers is emphasized, with their ability to encapsulate a range of therapeutic agents, including PD-1 inhibitors, and facilitate their targeted delivery to tumor locations. By manipulating the pore size and surface characteristics of ZIF-8 nanoparticles, controlled drug release can be realized. The strategic use of ZIF-8 nanoparticles to deliver PD-1 inhibitors presents a precise and targeted modality for cancer treatment, reducing off-target impacts and enhancing therapeutic effectiveness. This combined strategy addresses the existing challenges and constraints of current immunotherapy techniques, with the ultimate goal of enhancing patient outcomes in cancer therapy.

Efficacy and Safety of First-line Therapies for Advanced Unresectable Oesophageal Squamous Cell Cancer: a Systematic Review and Network Meta-analysis

AIM

To compare the clinical efficacy and safety of first-line treatments for advanced unresectable oesophageal squamous cell cancer.

MATERIALS AND METHODS

A systematic review and network meta-analysis was carried out by retrieving and retaining relevant literature from databases. The studies were randomised controlled trials comparing first-line treatments for advanced unresectable oesophageal squamous cell cancer. A Bayesian network meta-analysis was used to assess clinical outcomes.

RESULTS

Nine studies including 4499 patients receiving first-line treatments were analysed. For all populations, toripalimab plus chemotherapy tended to provide the best overall survival (hazard ratio 0.58, 95% confidence intervals 0.43-0.78) and sintilimab plus chemotherapy provided the best progression-free survival (0.56, 0.46-0.68). Nivolumab plus chemotherapy presented the best objective response rate (odds ratio 2.45, 1.78-3.42) and camrelizumab plus chemotherapy (0.47, 0.29-0.74) appeared to be the safest. Sintilimab plus chemotherapy (0.55, 0.40-0.75) and nivolumab (0.54, 0.37-0.80) plus chemotherapy had the best overall survival in programmed death ligand 1 (PD-L1) tumour proportion score <1% and ≥1% subgroups. Toripalimab plus chemotherapy (0.61, 0.40-0.93) and pembrolizumab (0.57, 0.43-0.75) were the best in overall survival in combined positive score <10 and ≥10 subgroups, respectively. Toripalimab plus chemotherapy showed the best overall survival in the Asian group; pembrolizumab presented better overall survival in the Asian population than the non-Asian group.

CONCLUSION

Most immunotherapy combined with chemotherapy showed superior clinical benefits and sintilimab plus chemotherapy, toripalimab plus chemotherapy and tislelizumab plus chemotherapy had better comprehensive clinical efficacy. PD-L1 expression detection and ethnicity differences are still of great significance and most suitable regimens varied from each subgroup.

Role of exosomes in metastasis and therapeutic resistance in esophageal cancer

Esophageal cancer (EC) has a high incidence and mortality rate and is emerging as one of the most common health problems globally. Owing to the lack of sensitive detection methods, uncontrollable rapid metastasis, and pervasive treatment resistance, EC is often diagnosed in advanced stages and is susceptible to local recurrence. Exosomes are important components of intercellular communication and the exosome-mediated crosstalk between the cancer and surrounding cells within the tumor microenvironment plays a crucial role in the metastasis, progression, and therapeutic resistance of EC. Considering the critical role of exosomes in tumor pathogenesis, this review focused on elucidating the impact of exosomes on EC metastasis and therapeutic resistance. Here, we summarized the relevant signaling pathways involved in these processes. In addition, we discussed the potential clinical applications of exosomes for the early diagnosis, prognosis, and treatment of EC.

Comprehensive Review: Unveiling the Pro-Oncogenic Roles of IL-1ß and PD-1/PD-L1 in NSCLC Development and Targeting Their Pathways for Clinical Management

In the past decade, targeted therapies for solid tumors, including non-small cell lung cancer (NSCLC), have advanced significantly, offering tailored treatment options for patients. However, individuals without targetable mutations pose a clinical challenge, as they may not respond to standard treatments like immune-checkpoint inhibitors (ICIs) and novel targeted therapies. While the mechanism of action of ICIs seems promising, the lack of a robust response limits their widespread use. Although the expression levels of programmed death ligand 1 (PD-L1) on tumor cells are used to predict ICI response, identifying new biomarkers, particularly those associated with the tumor microenvironment (TME), is crucial to address this unmet need. Recently, inflammatory cytokines such as interleukin-1 beta (IL-1β) have emerged as a key area of focus and hold significant potential implications for future clinical practice. Combinatorial approaches of IL-1β inhibitors and ICIs may provide a potential therapeutic modality for NSCLC patients without targetable mutations. Recent advancements in our understanding of the intricate relationship between inflammation and oncogenesis, particularly involving the IL-1β/PD-1/PD-L1 pathway, have shed light on their application in lung cancer development and clinical outcomes of patients. Targeting these pathways in cancers like NSCLC holds immense potential to revolutionize cancer treatment, particularly for patients lacking targetable genetic mutations. However, despite these promising prospects, there remain certain aspects of this pathway that require further investigation, particularly regarding treatment resistance. Therefore, the objective of this review is to delve into the role of IL-1β in NSCLC, its participation in inflammatory pathways, and its intricate crosstalk with the PD-1/PD-L1 pathway. Additionally, we aim to explore the potential of IL-1β as a therapeutic target for NSCLC treatment.