Tumor-associated macrophages affect the treatment of lung cancer

The role of the tumour microenvironment in lung cancer and its therapeutic implications

Lung cancer is the leading cause of cancer-related deaths globally, with tumour growth, invasion, and treatment response heavily influenced by the tumour microenvironment (TME). The TME promotes tumour progression by creating an immunosuppressive environment that hampers the body's antitumour immune response, primarily through the Nuclear Factor Kappa B (NF-κB) and Signal Transducer and Activator of Transcription 3 (STAT3) pathways. These pathways contribute to chronic inflammation, immune evasion, and angiogenesis. Targeting the TME and its signalling pathways has shown potential to enhance treatment efficacy. STAT3, a key transcription factor in lung cancer, drives tumour growth and immune suppression via the mTOR and JAK pathways. Inhibiting these pathways can block STAT3 and slow cancer progression. Promising results have been observed with mTOR inhibitors like CC-115 and Vistusertib, especially when combined with immune checkpoint inhibitors, and with JAK inhibitors such as Ruxolitinib, AZD4205, and Filgotinib. These strategies represent a promising direction for lung cancer therapy. This review explores the intricate relationship between the TME and lung cancer, focussing on novel therapeutic approaches that target immune cells, signalling molecules, and fibroblasts within the TME to improve patient outcomes.

Primary and Acquired Resistance to Immunotherapy with Checkpoint Inhibitors in NSCLC: From Bedside to Bench and Back

Immunotherapy with checkpoint inhibitors has become the cornerstone of systemic treatment for non-oncogene addicted non-small-cell lung cancer. Despite its pivotal role, a significant proportion of patients-approximately 70-85%-either exhibit primary resistance to PD-1 blockade or develop acquired resistance following an initial benefit, even in combination with chemotherapy and/or anti-CTLA-4 agents. The phenomenon of primary and acquired resistance to immunotherapy represents a critical clinical challenge, largely based on our incomplete understanding of the mechanisms of action of immunotherapy, and the resulting lack of accurate predictive biomarkers. Here, we review the definitions and explore the proposed mechanisms of primary and acquired resistance, including those related to the tumor microenvironment, systemic factors, and intrinsic tumor characteristics. We also discuss translational data on adaptive changes within tumor cells and the immune infiltrate following exposure to checkpoint inhibitors. Lastly, we offer a comprehensive overview of current and emerging therapeutic strategies designed to prevent primary resistance and counteract acquired resistance.

Hypoxia studies in non‑small cell lung cancer: Pathogenesis and clinical implications (Review)

Non‑small cell lung cancer (NSCLC) is one of the most prevalent and lethal types of cancers worldwide and its high incidence and mortality rates pose a significant public health challenge. Despite significant advances in targeted therapy and immunotherapy, the overall prognosis of patients with NSCLC remains poor. Hypoxia is a critical driving factor in tumor progression, influencing the biological behavior of tumor cells through complex molecular mechanisms. The present review systematically examined the role of the hypoxic microenvironment in NSCLC, demonstrating its crucial role in promoting tumor cell growth, invasion and metastasis. Additionally, it has been previously reported that the hypoxic microenvironment enhances tumor cell resistance by activating hypoxia‑inducible factor and regulating exosome secretion. The hypoxic microenvironment also enables tumor cells to adapt to low oxygen and nutrient‑deficient conditions by enhancing metabolic reprogramming, such as through upregulating glycolysis. Further studies have shown that the hypoxic microenvironment facilitates immune escape by modulating tumor‑associated immune cells and suppressing the antitumor response of the immune system. Moreover, the hypoxic microenvironment increases tumor resistance to radiotherapy, chemotherapy and other types of targeted therapy through various pathways, significantly reducing the therapeutic efficacy of these treatments. Therefore, it could be suggested that early detection of cellular hypoxia and targeted therapy based on hypoxia may offer new therapeutic approaches for patients with NSCLC. The present review not only deepened the current understanding of the mechanisms of action and role of the hypoxic microenvironment in NSCLC but also provided a solid theoretical basis for the future development of precision treatments for patients with NSCLC.

Targeting HLA-E in Lung Cancer: The Therapeutic Potential of IRF5-Engineered M1-Macrophage-Derived Exosomes

Immunotherapy is a pivotal approach in the treatment of lung cancer. Although HLA-E is a potential target for tumor immunotherapy, its role in lung cancer remains unclear. Previous studies have identified the transcription factor IRF5 as a characteristic gene of M1-like macrophages, highlighting its crucial role in promoting antitumor immune responses. In this study, we developed an engineered M1-like macrophage exosomes expressing IRF5 (IRF5 M1-exos) and demonstrated their ability to inhibit proliferation, migration, and invasion of lung cancer cells. Moreover, our experiments using a nude mouse model revealed that IRF5 M1-exos exerted potent therapeutic effects by effectively suppressing tumor growth. Notably, the mechanism by which IRF5 exerts its antitumor function through HLA-E regulation in lung cancer has not been fully elucidated. Here, we identified HLA-E as a downstream target gene of IRF5 and demonstrated that the overexpression of HLA-E can counteract the tumor-promoting effects induced by si-IRF5 M1-exos. These results suggest that M1 macrophage-derived exosomes, enriched with the transcription factor IRF5, exhibit potent antitumor activity by up-regulating HLA-E in lung cancer cells. Therefore, IRF5 M1-exos represent an attractive therapeutic strategy for lung cancer.

A detailed insight into macrophages' role in shaping lung carcinogenesis

Despite significant advancements in cancer treatment in recent decades, the high mortality rate associated with lung cancer remains a significant concern. The development and proper execution of new targeted therapies needs more deep knowledge regarding the lung cancer associated tumour microenvironment. One of the key component of that tumour microenvironment is the lung resident macrophages. Although in normal physiological condition the lung resident macrophages are believed to maintain lung homeostasis, but they may also initiate a vicious inflammatory response in abnormal conditions which is linked to lung cancer development. Depending on the activation pathway, the lung resident macrophages are either of M1 or M2 sub-type. The M1 and M2 sub-types differ significantly in various prospectuses, from phenotypic markers to metabolic pathways. In addition to this generalized classification, the recent advancement of the multiomics technology is able to identify some other sub-types of lung resident macrophages. Researchers have also observed that these different sub-types can manipulate the pathogenesis of lung carcinogenesis in a context dependent manner and can either promote or inhibit the development of lung carcinogenesis upon receiving proper activation. As proper knowledge about the role played by the lung resident macrophages' in shaping the lung carcinogenesis is limited, so the main purpose of this review is to bring all the available information under the same roof. We also elaborated the different mechanisms involved in maintenance of the plasticity of M1/M2 sub-type, as this plasticity can be a good target for lung cancer treatment.