Targeting the IGF-Axis Potentiates Immunotherapy for Pancreatic Ductal Adenocarcinoma Liver Metastases by Altering the Immunosuppressive Microenvironment

T cell exhaustion in human cancers

T cell exhaustion refers to a progressive state in which T cells become functionally impaired due to sustained antigenic stimulation, which is characterized by increased expression of immune inhibitory receptors, but weakened effector functions, reduced self-renewal capacity, altered epigenetics, transcriptional programme and metabolism. T cell exhaustion is one of the major causes leading to immune escape of cancer, creating an environment that supports tumor development and metastatic spread. In addition, T cell exhaustion plays a pivotal role to the efficacy of current immunotherapies for cancer. This review aims to provide a comprehensive view of roles of T cell exhaustion in cancer development and progression. We summerized the regulatory mechanisms that involved in T cell exhaustion, including transcription factors, epigenetic and metabolic reprogramming events, and various microenvironmental factors such as cytokines, microorganisms, and tumor autocrine substances. The paper also discussed the challenges posed by T cell exhaustion to cancer immunotherapies, including immune checkpoint blockade (ICB) therapies and chimeric antigen receptor T cell (CAR-T) therapy, highlightsing the obstacles encountered in ICB therapies and CAR-T therapies due to T cell exhaustion. Finally, the article provides an overview of current therapeutic options aimed to reversing or alleviating T cell exhaustion in ICB and CAR-T therapies. These therapeutic approaches seek to overcome T cell exhaustion and enhance the effectiveness of immunotherapies in treating tumors.

Inhibition of insulin-like growth factors increases production of CXCL9/10 by macrophages and fibroblasts and facilitates CD8+ cytotoxic T cell recruitment to pancreatic tumours

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy with an urgent unmet clinical need for new therapies. Using a combination of in vitro assays and in vivo preclinical models we demonstrate that therapeutic inhibition of the IGF signalling axis promotes the accumulation of CD8+ cytotoxic T cells within the tumour microenvironment of PDAC tumours. Mechanistically, we show that IGF blockade promotes macrophage and fibroblast production of the chemokines CXCL9 and CXCL10 to facilitate CD8+ T cell recruitment and trafficking towards the PDAC tumour. Exploring this pathway further, we show that IGF inhibition leads to increased STAT1 transcriptional activity, correlating with a downregulation of the AKT/STAT3 signalling axis, in turn promoting Cxcl9 and Cxcl10 gene transcription. Using patient derived tumour explants, we also demonstrate that our findings translate into the human setting. PDAC tumours are frequently described as "immunologically cold", therefore bolstering CD8+ T cell recruitment to PDAC tumours through IGF inhibition may serve to improve the efficacy of immune checkpoint inhibitors which rely on the presence of CD8+ T cells in tumours.

Extracellular Interactors of the IGF System: Impact on Cancer Hallmarks and Therapeutic Approaches

Dysregulation of the insulin-like growth factor (IGF) system determines the onset of various pathological conditions, including cancer. Accordingly, therapeutic strategies have been developed to block this system in tumor cells, but the results of clinical trials have been disappointing. After decades of research in the field, it is safe to say that one of the major reasons underlying the poor efficacy of anti-IGF-targeting agents is derived from an underestimation of the molecular complexity of this axis. Genetic, transcriptional, post-transcriptional and functional interactors interfere with the activity of canonical components of this axis, supporting the need for combinatorial approaches to effectively block this system. In addition, cancer cells interface with a multiplicity of factors from the extracellular compartment, which strongly affect cell destiny. In this review, we will cover novel extracellular mechanisms contributing to IGF system dysregulation and the implications of such dangerous liaisons for cancer hallmarks and responses to known and new anti-IGF drugs. A deeper understanding of both the intracellular and extracellular microenvironments might provide new impetus to better decipher the complexity of the IGF axis in cancer and provide new clues for designing novel therapeutic approaches.

Biomarkers for predicting tumor response to PD-1 inhibitors in patients with advanced pancreatic cancer

Pancreatic cancer is among the most lethal malignant neoplasms, and few patients with pancreatic cancer benefit from immunotherapy. We retrospectively analyzed advanced pancreatic cancer patients who received PD-1 inhibitor-based combination therapies during 2019-2021 in our institution. The clinical characteristics and peripheral blood inflammatory markers (neutrophil-to-lymphocyte ratio [NLR], platelet-to-lymphocyte ratio [PLR], lymphocyte-to-monocyte ratio [LMR], and lactate dehydrogenase [LDH]) were collected at baseline. Chi-squared and Fisher's exact tests were used to evaluate relationships between the above parameters and tumor response. Cox regression analyses were employed to assess the effects of baseline factors on patients' survival and immune-related adverse events (irAEs). Overall, 67 patients who received at least two cycles of PD-1 inhibitor were considered evaluable. A lower NLR was independent predictor for objective response rate (38.1% vs. 15.2%, P = .037) and disease control rate (81.0% vs. 52.2%, P = .032). In our study population, patients with lower LDH had superior progression-free survival (PFS) and overall survival(OS) (mPFS, 5.4 vs. 2.8 months, P < .001; mOS, 13.3 vs. 3.6 months, P < .001). Liver metastasis was verified to be a negative prognostic factor for PFS (2.4 vs. 7.8 months, P < .001) and OS (5.7 vs. 18.0 months, P < .001). The most common irAEs were hypothyroidism (13.4%) and rash (10.5%). Our study demonstrated that the pretreatment inflammatory markers were independent predictors for tumor response, and the baseline LDH level and liver metastasis were potential prognostic markers of survival in patients with pancreatic cancer treated with PD-1 inhibitors.

Molecular and metabolic regulation of immunosuppression in metastatic pancreatic ductal adenocarcinoma

Immunosuppression is a hallmark of pancreatic ductal adenocarcinoma (PDAC), contributing to early metastasis and poor patient survival. Compared to the localized tumors, current standard-of-care therapies have failed to improve the survival of patients with metastatic PDAC, that necessecitates exploration of novel therapeutic approaches. While immunotherapies such as immune checkpoint blockade (ICB) and therapeutic vaccines have emerged as promising treatment modalities in certain cancers, limited responses have been achieved in PDAC. Therefore, specific mechanisms regulating the poor response to immunotherapy must be explored. The immunosuppressive microenvironment driven by oncogenic mutations, tumor secretome, non-coding RNAs, and tumor microbiome persists throughout PDAC progression, allowing neoplastic cells to grow locally and metastasize distantly. The metastatic cells escaping the host immune surveillance are unique in molecular, immunological, and metabolic characteristics. Following chemokine and exosomal guidance, these cells metastasize to the organ-specific pre-metastatic niches (PMNs) constituted by local resident cells, stromal fibroblasts, and suppressive immune cells, such as the metastasis-associated macrophages, neutrophils, and myeloid-derived suppressor cells. The metastatic immune microenvironment differs from primary tumors in stromal and immune cell composition, functionality, and metabolism. Thus far, multiple molecular and metabolic pathways, distinct from primary tumors, have been identified that dampen immune effector functions, confounding the immunotherapy response in metastatic PDAC. This review describes major immunoregulatory pathways that contribute to the metastatic progression and limit immunotherapy outcomes in PDAC. Overall, we highlight the therapeutic vulnerabilities attributable to immunosuppressive factors and discuss whether targeting these molecular and immunological "hot spots" could improve the outcomes of PDAC immunotherapies.

IGF2: A Role in Metastasis and Tumor Evasion from Immune Surveillance?

Insulin-like growth factor 2 (IGF2) is upregulated in both childhood and adult malignancies. Its overexpression is associated with resistance to chemotherapy and worse prognosis. However, our understanding of its physiological and pathological role is lagging behind what we know about IGF1. Dysregulation of the expression and function of IGF2 receptors, insulin receptor isoform A (IR-A), insulin growth factor receptor 1 (IGF1R), and their downstream signaling effectors drive cancer initiation and progression. The involvement of IGF2 in carcinogenesis depends on its ability to link high energy intake, increase cell proliferation, and suppress apoptosis to cancer risk, and this is likely the key mechanism bridging insulin resistance to cancer. New aspects are emerging regarding the role of IGF2 in promoting cancer metastasis by promoting evasion from immune destruction. This review provides a perspective on IGF2 and an update on recent research findings. Specifically, we focus on studies providing compelling evidence that IGF2 is not only a major factor in primary tumor development, but it also plays a crucial role in cancer spread, immune evasion, and resistance to therapies. Further studies are needed in order to find new therapeutic approaches to target IGF2 action.

Research Progress on the Microenvironment and Immunotherapy of Advanced Non-Small Cell Lung Cancer With Liver Metastases

Lung cancer is a malignant tumor with the highest morbidity and mortality, and more than 75% of patients are diagnosed at an advanced stage. Liver metastases occur in 20% of non-small cell lung cancer patients, and their prognosis are poor. In recent years, immune checkpoint inhibitor monotherapy and combination therapy have made breakthrough progress in advanced Non-small cell lung cancer (NSCLC) patients. However, compared with the overall population, the liver metastases population was an independent prognostic factor for poor immunotherapy response. Whether and how immunotherapy can work in NSCLC patients with liver metastases is a major and unresolved challenge. Although more and more data have been disclosed, the research progress of NSCLC liver metastasis is still limited. How liver metastasis modulates systemic antitumor immunity and the drug resistance mechanisms of the liver immune microenvironment have not been elucidated. We systematically focused on non-small cell lung cancer patients with liver metastases, reviewed and summarized their pathophysiological mechanisms, immune microenvironment characteristics, and optimization of immunotherapy strategies.