Special Issue "Signaling Pathways and Immune Checkpoint Regulation in Cancer"

A special issue of Cancers (ISSN 2072-6694).

Deadline for manuscript submissions: closed (31 March 2019).

Special Issue Editor

Prof. Dr. Georgios Rassidakis
E-Mail Website
Guest Editor
Department of Oncology - Pathology, Karolinska Institutet, & Department of Pathology and Cytology, Karolinska University Hospital, Stockholm, Sweden
Interests: ALK signalling; Immune checkpoint regulation; mTOR sigalling; AP-1 transcription factors; p53 pathway; Mechanisms of lymphomagenesis; Mechanisms of drug resistance; T-cell lymphomas

Special Issue Information

Dear colleagues,

Intensive research over the last decades has uncovered the dynamic interactions between cancer cells and host immune cells, namely T-lymphocytes, NK cells, dendritic cells and histiocytes. The immune checkpoint plays a crucial role in the immune response against tumor cells, and therefore, better understanding of the underlying mechanisms led to the development of novel immunotherapeutic approaches in cancer. The basic concept of immunotherapy is that the target molecule is on the immune cell and not on the tumor cell, and therefore the same strategy would work on many different cancer cell types with different phenotype and genetic backgrounds. Immune checkpoint therapy initially focused on CTLA-4 with promising results. More recently, the PD-1 (programmed death-1) and its ligand (PD-L1) have been targeted with anti-PD-1 and anti-PD-L1 antibodies, which are currently being tested in clinical trials in a variety of cancers with clinical success. In certain tumor types, immunotherapy efficiency has been associated with PD-L1 protein levels. PD-L1 expression can be regulated at the genetic (e.g. PD-L1 gene amplification), transcriptional and post-translational level, however, the exact mechanisms may be cell type-specific and they are still under investigation. Transcription factors, known to regulate PD-L1 gene expression, commonly operate as targets of known oncogenic signaling pathways, thus providing the biologic rationale for combination treatment strategies such as immunotherapy with targeted therapy.

This Special Issue focuses on the mechanisms of immune checkpoint regulation by oncogenic signaling pathways that may represent novel therapeutic targets, as well as the role of the tumor microenvironment. In addition, immunotherapy-related studies including PD-1/PD-L1 antibodies and CART-T cell therapy are most welcome for publication consideration in this issue.

Prof. Dr. Georgios Rassidakis
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Cancers is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • signaling pathways
  • immune checkpoint regulation
  • CTLA-4
  • PD-L1
  • CART-T cell therapy
  • immunotherapy
  • targeted therapy
  • transcription factors

Published Papers (12 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Jump to: Review

Open AccessArticle
Dissecting the Prognostic Significance and Functional Role of Progranulin in Chronic Lymphocytic Leukemia
Cancers 2019, 11(6), 822; https://0-doi-org.brum.beds.ac.uk/10.3390/cancers11060822 - 13 Jun 2019
Cited by 1 | Viewed by 1667
Abstract
Chronic lymphocytic leukemia (CLL) is known for its strong dependency on the tumor microenvironment. We found progranulin (GRN), a protein that has been linked to inflammation and cancer, to be upregulated in the serum of CLL patients compared to healthy controls, and increased [...] Read more.
Chronic lymphocytic leukemia (CLL) is known for its strong dependency on the tumor microenvironment. We found progranulin (GRN), a protein that has been linked to inflammation and cancer, to be upregulated in the serum of CLL patients compared to healthy controls, and increased GRN levels to be associated with an increased hazard for disease progression and death. This raised the question of whether GRN is a functional driver of CLL. We observed that recombinant GRN did not directly affect viability, activation, or proliferation of primary CLL cells in vitro. However, GRN secretion was induced in co-cultures of CLL cells with stromal cells that enhanced CLL cell survival. Gene expression profiling and protein analyses revealed that primary mesenchymal stromal cells (MSCs) in co-culture with CLL cells acquire a cancer-associated fibroblast-like phenotype. Despite its upregulation in the co-cultures, GRN treatment of MSCs did not mimic this effect. To test the relevance of GRN for CLL in vivo, we made use of the Eμ-TCL1 CLL mouse model. As we detected strong GRN expression in myeloid cells, we performed adoptive transfer of Eμ-TCL1 leukemia cells to bone marrow chimeric Grn−/− mice that lack GRN in hematopoietic cells. Thereby, we observed that CLL-like disease developed comparable in Grn−/− chimeras and respective control mice. In conclusion, serum GRN is found to be strongly upregulated in CLL, which indicates potential use as a prognostic marker, but there is no evidence that elevated GRN functionally drives the disease. Full article
(This article belongs to the Special Issue Signaling Pathways and Immune Checkpoint Regulation in Cancer)
Show Figures

Figure 1

Open AccessArticle
Expression of PD-1 and PD-L1 in Extramammary Paget Disease: Implications for Immune-Targeted Therapy
Cancers 2019, 11(6), 754; https://0-doi-org.brum.beds.ac.uk/10.3390/cancers11060754 - 29 May 2019
Cited by 9 | Viewed by 1679
Abstract
Extramammary Paget disease (EMPD) is a locally aggressive cutaneous malignancy that usually arises in anogenital or axillary skin. Immune checkpoint inhibitors targeting programmed cell death receptor (PD-1) and/or its ligand (PD-L1) are approved for the treatment of several types of cancer, and response [...] Read more.
Extramammary Paget disease (EMPD) is a locally aggressive cutaneous malignancy that usually arises in anogenital or axillary skin. Immune checkpoint inhibitors targeting programmed cell death receptor (PD-1) and/or its ligand (PD-L1) are approved for the treatment of several types of cancer, and response to these generally correlates with increased PD-L1 expression by tumor cells. The expression of PD-L1 and composition and density of the tumor-associated immune infiltrate in EMPD have been little studied. To determine whether EMPD might be amenable to immune checkpoint blockade, we analyzed the expression of PD-1 and PD-L1 and the composition and density of the tumor-associated immune infiltrate in EMPD and evaluated associations between biomarker expression and clinicopathologic parameters. Twenty-one EMPD tumors were evaluated for tumor cell PD-L1 expression and for relative expression and distribution of CD3, CD8, PD-1, and PD-L1 in the tumor-associated immune infiltrate by using a combination of visual and image analysis (Aperio ImageScope). In addition, PD-L1 expression was assessed in 10 cases of mammary Paget disease (MPD). In EMPD cases, PD-L1 was expressed by tumor cells (3/21; 14%) and the tumor-associated immune infiltrate (15/21; 71%), and PD-1 was expressed by the tumor-associated immune infiltrate in all cases analyzed (18/18). However, PD-L1 expression by EMPD tumor cells did not correlate with the density of CD3-, CD8-, or PD-1-positive cells in the tumor-associated immune infiltrate or other clinicopathologic parameters. Furthermore, the density of CD3, CD8, PD-1, and PD-L1 in the tumor-associated immune infiltrate did not correlate with any clinicopathologic parameters evaluated with the exception that CD3 positive values were significantly higher in patients who were still alive (median, 1310 cells/mm2; range, 543–2115;) than in those who died (median, 611 cells/mm2; range, 481–908; p = 0.049). In all MPD cases, PD-L1 was absent in tumor cells but present in the tumor-associated immune infiltrate, and PD-L1 expression in lymphocytes was lower in patients with HER2/neu-positive than in those with HER2/neu-negative disease (p = 0.07). Our findings raise the possibility of therapeutic targeting of the PD-1/PD-L1 axis in EMPD. Full article
(This article belongs to the Special Issue Signaling Pathways and Immune Checkpoint Regulation in Cancer)
Show Figures

Figure 1

Open AccessArticle
PD1/PD-L1 Expression in Blastic Plasmacytoid Dendritic Cell Neoplasm
Cancers 2019, 11(5), 695; https://0-doi-org.brum.beds.ac.uk/10.3390/cancers11050695 - 19 May 2019
Cited by 4 | Viewed by 1805
Abstract
Patients with blastic plasmacytoid dendritic cell neoplasm (BPDCN) have poor outcomes despite intensive chemotherapy, underscoring the need for novel therapeutic approaches. The expression status of PD1/PD-L1 in BPDCN remains unknown. We evaluated PD1/PD-L1 by immunohistochemistry and RNAseq expression profiling in a cohort of [...] Read more.
Patients with blastic plasmacytoid dendritic cell neoplasm (BPDCN) have poor outcomes despite intensive chemotherapy, underscoring the need for novel therapeutic approaches. The expression status of PD1/PD-L1 in BPDCN remains unknown. We evaluated PD1/PD-L1 by immunohistochemistry and RNAseq expression profiling in a cohort of BPDCN patients. The study group included 28 patients with a median age of 66.8 years (range, 22.8–86.7), 22 men and 6 women. PD-L1 expression was detected by immunohistochemistry in 10/21 (47.6%) cases. PD-L1 expression had a median H-score of 157. The H-score was ≥60 in 7 patients. PD-L1 protein levels (H-score) were proportional to normalized PD-L1 mRNA transcript levels (CD274 mRNA). In addition, high-level PD-L1 expression correlated with higher numbers of PD1-positive cells within BPDCN tumors. There was no correlation between clinicopathologic characteristics and PD-L1 expression status. Similarly, there was no significant difference in overall survival between patients with PD-L1-positive and PD-L1-negative BPDCN (median 12 vs. 23 month, respectively; p = 0.743). In conclusion, PD-L1 expression by tumor cells is detectable in a sizeable subset of patients with BPDCN, suggesting that exploration of the effectiveness of therapeutic inhibition of the PD1/PD-L1 axis in patients with refractory or progressive BPDCN is warranted. Full article
(This article belongs to the Special Issue Signaling Pathways and Immune Checkpoint Regulation in Cancer)
Show Figures

Figure 1

Open AccessArticle
Immunophenotype of T Cells Expressing Programmed Death-1 and Cytotoxic T Cell Antigen-4 in Early Lung Cancer: Local vs. Systemic Immune Response
Cancers 2019, 11(4), 567; https://0-doi-org.brum.beds.ac.uk/10.3390/cancers11040567 - 21 Apr 2019
Cited by 7 | Viewed by 1481
Abstract
The overexpression of programmed death-1 (PD-1) and cytotoxic T cell antigen 4 (CTLA-4) receptors on T cells are among the major mechanisms of tumor immunoevasion. However, the expression pattern of these receptors on T cell subpopulations of a different activation status and at [...] Read more.
The overexpression of programmed death-1 (PD-1) and cytotoxic T cell antigen 4 (CTLA-4) receptors on T cells are among the major mechanisms of tumor immunoevasion. However, the expression pattern of these receptors on T cell subpopulations of a different activation status and at different sites is poorly characterized. Thus, we analyzed the expression of PD-1 and CTLA-4 on the naïve, activated, memory, and activated memory T cells. Bronchoalveolar lavage fluid (BALF) from the lung affected by lung cancer (clBALF), the opposite ‘healthy’ lung (hlBALF), and peripheral blood (PB) samples were collected from 32 patients. The cells were analyzed by multiparameter flow cytometry. The proportion of memory, activated, and activated memory CD8+ cells with the expression of PD-1 and CTLA-4 were elevated in the clBALF when compared to the hlBALF (insignificantly), but these proportions were significantly higher in the BALF when compared with the PB. The proportions of PD-1+ and CTLA-4+ T cells were elevated in the squamous cell carcinoma when compared to the adenocarcinoma patients. Also, the expression of PD-1 and CTLA-4 on T cells from the BALF was significantly higher than from PB. We report for the first time the differential expression of checkpoint molecules on CD4+ and CD8+ lymphocytes at a different stage of activation in the local environment of lung cancer. Moreover, the circulating T cells have a distinct expression of these receptors, which suggests their poor utility as biomarkers for immunotherapy. Full article
(This article belongs to the Special Issue Signaling Pathways and Immune Checkpoint Regulation in Cancer)
Show Figures

Figure 1

Review

Jump to: Research

Open AccessReview
LAG3: The Biological Processes That Motivate Targeting This Immune Checkpoint Molecule in Human Cancer
Cancers 2019, 11(8), 1213; https://0-doi-org.brum.beds.ac.uk/10.3390/cancers11081213 - 20 Aug 2019
Cited by 23 | Viewed by 2229
Abstract
The programmed cell death 1 (PD-1) pathway is an important regulator of immune responses in peripheral tissues, including abnormal situations such as the tumor microenvironment. This pathway is currently the principal target for immunotherapeutic compounds designed to block immune checkpoint pathways, with these [...] Read more.
The programmed cell death 1 (PD-1) pathway is an important regulator of immune responses in peripheral tissues, including abnormal situations such as the tumor microenvironment. This pathway is currently the principal target for immunotherapeutic compounds designed to block immune checkpoint pathways, with these drugs improving clinical outcomes in a number of solid and hematological tumors. Medical oncology is experiencing an immune revolution that has scientists and clinicians looking at alternative, non-redundant inhibitory pathways also involved in regulating immune responses in cancer. A variety of targets have emerged for combinatorial approaches in immune checkpoint blockade. The main purpose of this narrative review is to summarize the biological role of lymphocyte activation gene 3 (LAG3), an emerging targetable inhibitory immune checkpoint molecule. We briefly discuss its role in infection, autoimmune disease and cancer, with a more detailed analysis of current data on LAG3 expression in breast cancer. Current clinical trials testing soluble LAG3 immunoglobulin and LAG3 antagonists are also presented in this work. Full article
(This article belongs to the Special Issue Signaling Pathways and Immune Checkpoint Regulation in Cancer)
Show Figures

Figure 1

Open AccessReview
Immunotherapy in Hodgkin Lymphoma: Present Status and Future Strategies
Cancers 2019, 11(8), 1071; https://0-doi-org.brum.beds.ac.uk/10.3390/cancers11081071 - 29 Jul 2019
Cited by 12 | Viewed by 2064
Abstract
Although classical Hodgkin lymphoma (cHL) is usually curable, 20–30% of the patients experience treatment failure and most of them are typically treated with salvage chemotherapy and autologous stem cell transplantation (autoSCT). However, 45–55% of that subset further relapse or progress despite intensive treatment. [...] Read more.
Although classical Hodgkin lymphoma (cHL) is usually curable, 20–30% of the patients experience treatment failure and most of them are typically treated with salvage chemotherapy and autologous stem cell transplantation (autoSCT). However, 45–55% of that subset further relapse or progress despite intensive treatment. At the advanced stage of the disease course, recently developed immunotherapeutic approaches have provided very promising results with prolonged remissions or disease stabilization in many patients. Brentuximab vedotin (BV) has been approved for patients with relapsed/refractory cHL (rr-cHL) who have failed autoSCT, as a consolidation after autoSCT in high-risk patients, as well as for patients who are ineligible for autoSCT or multiagent chemotherapy who have failed ≥ two treatment lines. However, except of the consolidation setting, 90–95% of the patients will progress and require further treatment. In this clinical setting, immune checkpoint inhibitors (CPIs) have produced impressive results. Both nivolumab and pembrolizumab have been approved for rr-cHL after autoSCT and BV failure, while pembrolizumab has also been licensed for transplant ineligible patients after BV failure. Other CPIs, sintilimab and tislelizumab, have been successfully tested in China, albeit in less heavily pretreated populations. Recent data suggest that the efficacy of CPIs may be augmented by hypomethylating agents, such as decitabine. As a result of their success in heavily pretreated disease, BV and CPIs are moving to earlier lines of treatment. BV was recently licensed by the FDA for the first-line treatment of stage III/IV Hodgkin lymphoma (HL) in combination with AVD (only stage IV according to the European Medicines Agency (EMA)). CPIs are currently being evaluated in combination with AVD in phase II trials of first-line treatment. The impact of BV and CPIs was also investigated in the setting of second-line salvage therapy. Finally, combinations of targeted therapies are under evaluation. Based on these exciting results, it appears reasonable to predict that an improvement in survival and a potential increase in the cure rates of cHL will soon become evident. Full article
(This article belongs to the Special Issue Signaling Pathways and Immune Checkpoint Regulation in Cancer)
Open AccessReview
Strategies to Augment Natural Killer (NK) Cell Activity against Solid Tumors
Cancers 2019, 11(7), 1040; https://0-doi-org.brum.beds.ac.uk/10.3390/cancers11071040 - 23 Jul 2019
Cited by 19 | Viewed by 3450
Abstract
The immune system plays a crucial role to prevent local growth and dissemination of cancer. Therapies based on activating the immune system can result in beneficial responses in patients with metastatic disease. Treatment with antibodies targeting the immunological checkpoint axis PD-1 / PD-L1 [...] Read more.
The immune system plays a crucial role to prevent local growth and dissemination of cancer. Therapies based on activating the immune system can result in beneficial responses in patients with metastatic disease. Treatment with antibodies targeting the immunological checkpoint axis PD-1 / PD-L1 can result in the induction of anti-tumor T cell activation leading to meaningful long-lasting clinical responses. Still, many patients acquire resistance or develop dose-limiting toxicities to these therapies. Analysis of tumors from patients who progress on anti-PD-1 treatment reveal defective interferon-signaling and antigen presentation, resulting in immune escape from T cell-mediated attack. Natural killer (NK) cells are innate lymphocytes that can kill tumor cells without prior sensitization to antigens and can be activated to kill tumor cells that have an impaired antigen processing and presentation machinery. Thus, NK cells may serve as useful effectors against tumor cells that have become resistant to classical immune checkpoint therapy. Various approaches to activate NK cells are being increasingly explored in clinical trials against cancer. While clinical benefit has been demonstrated in patients with acute myeloid leukemia receiving haploidentical NK cells, responses in patients with solid tumors are so far less encouraging. Several hurdles need to be overcome to provide meaningful clinical responses in patients with solid tumors. Here we review the recent developments to augment NK cell responses against solid tumors with regards to cytokine therapy, adoptive infusion of NK cells, NK cell engagers, and NK cell immune checkpoints. Full article
(This article belongs to the Special Issue Signaling Pathways and Immune Checkpoint Regulation in Cancer)
Show Figures

Figure 1

Open AccessReview
AP-1 Transcription Factors as Regulators of Immune Responses in Cancer
Cancers 2019, 11(7), 1037; https://0-doi-org.brum.beds.ac.uk/10.3390/cancers11071037 - 23 Jul 2019
Cited by 28 | Viewed by 2128
Abstract
Immune check point blockade therapy has revolutionized the standard of cancer treatment and is credited with producing remarkable tumor remissions and increase in overall survival. This unprecedented clinical success however is feasible for a limited number of cancer patients due to resistance occurring [...] Read more.
Immune check point blockade therapy has revolutionized the standard of cancer treatment and is credited with producing remarkable tumor remissions and increase in overall survival. This unprecedented clinical success however is feasible for a limited number of cancer patients due to resistance occurring before or during a course of immunotherapy, which is often associated with activation of oncogenic signaling pathways, co-inhibitory checkpoints upregulation or expansion of immunosuppressive regulatory T-cells (Tregs) in the tumor microenviroment (TME). Targeted therapy aiming to inactivate a signaling pathway such as the Mitogen Activated Protein Kinases (MAPKs) has recently received a lot of attention due to emerging data from preclinical studies indicating synergy with immune checkpoint blockade therapy. The dimeric transcription factor complex Activator Protein-1 (AP-1) is a group of proteins involved in a wide array of cell processes and a critical regulator of nuclear gene expression during T-cell activation. It is also one of the downstream targets of the MAPK signaling cascade. In this review, we will attempt to unravel the roles of AP-1 in the regulation of anti-tumor immune responses, with a focus on the regulation of immune checkpoints and Tregs, seeking to extract useful insights for more efficacious immunotherapy. Full article
(This article belongs to the Special Issue Signaling Pathways and Immune Checkpoint Regulation in Cancer)
Show Figures

Figure 1

Open AccessReview
Targeting the Immune Microenvironment in Lymphomas of B-Cell Origin: From Biology to Clinical Application
Cancers 2019, 11(7), 915; https://0-doi-org.brum.beds.ac.uk/10.3390/cancers11070915 - 29 Jun 2019
Cited by 12 | Viewed by 1703
Abstract
In lymphomas of B-cell origin, cancer cells orchestrate an inflammatory microenvironment of immune and stromal cells that sustain the tumor cell survival and growth, known as a tumor microenvironment (TME). The features of the TME differ between the different lymphoma types, ranging from [...] Read more.
In lymphomas of B-cell origin, cancer cells orchestrate an inflammatory microenvironment of immune and stromal cells that sustain the tumor cell survival and growth, known as a tumor microenvironment (TME). The features of the TME differ between the different lymphoma types, ranging from extremely inflammatory, such as in Hodgkin lymphoma, to anergic, leading to immune deficiency and susceptibility to infections, such as in chronic lymphocytic leukemia. Understanding the characteristic features of the TME as well as the interactions between cancer and TME cells has given insight into the pathogenesis of most lymphomas and contributed to identify novel therapeutic targets. Here, we summarize the preclinical data that contributed to clarifying the role of the immune cells in the TME of different types of lymphomas of B-cell origin, and explain how the understanding of the biological background has led to new clinical applications. Moreover, we provide an overview of the clinical results of trials that assessed the safety and efficacy of drugs directly targeting TME immune cells in lymphoma patients. Full article
(This article belongs to the Special Issue Signaling Pathways and Immune Checkpoint Regulation in Cancer)
Show Figures

Figure 1

Open AccessReview
Beyond PD-1/PD-L1 Inhibition: What the Future Holds for Breast Cancer Immunotherapy
Cancers 2019, 11(5), 628; https://0-doi-org.brum.beds.ac.uk/10.3390/cancers11050628 - 05 May 2019
Cited by 20 | Viewed by 3269
Abstract
Cancer immunotherapy has altered the management of human malignancies, improving outcomes in an expanding list of diseases. Breast cancer - presumably due to its perceived low immunogenicity - is a late addition to this list. Furthermore, most of the focus has been on [...] Read more.
Cancer immunotherapy has altered the management of human malignancies, improving outcomes in an expanding list of diseases. Breast cancer - presumably due to its perceived low immunogenicity - is a late addition to this list. Furthermore, most of the focus has been on the triple negative subtype because of its higher tumor mutational load and lymphocyte-enriched stroma, although emerging data show promise on the other breast cancer subtypes as well. To this point the clinical use of immunotherapy is limited to the inhibition of two immune checkpoints, Programmed Cell Death Protein 1 (PD-1) and Cytotoxic T-lymphocyte-associated Protein 4 (CTLA-4). Consistent with the complexity of the regulation of the tumor – host interactions and their lack of reliance on a single regulatory pathway, combinatory approaches have shown improved efficacy albeit at the cost of increased toxicity. Beyond those two checkpoints though, a large number of co-stimulatory or co-inhibitory molecules play major roles on tumor evasion from immunosurveillance. These molecules likely represent future targets of immunotherapy provided that the promise shown in early data is translated into improved patient survival in randomized trials. The biological role, prognostic and predictive implications regarding breast cancer and early clinical efforts on exploiting these immune-related therapeutic targets are herein reviewed. Full article
(This article belongs to the Special Issue Signaling Pathways and Immune Checkpoint Regulation in Cancer)
Show Figures

Figure 1

Open AccessReview
Immune Checkpoint Ligand Reverse Signaling: Looking Back to Go Forward in Cancer Therapy
Cancers 2019, 11(5), 624; https://0-doi-org.brum.beds.ac.uk/10.3390/cancers11050624 - 04 May 2019
Cited by 16 | Viewed by 2554
Abstract
The so-called immune checkpoints are pathways that regulate the timing and intensity of the immune response to avoid an excessive reaction and to protect the host from autoimmunity. Immune checkpoint inhibitors (ICIs) are designed to target the negative regulatory pathways of T cells, [...] Read more.
The so-called immune checkpoints are pathways that regulate the timing and intensity of the immune response to avoid an excessive reaction and to protect the host from autoimmunity. Immune checkpoint inhibitors (ICIs) are designed to target the negative regulatory pathways of T cells, and they have been shown to restore anti-tumor immune functions and achieve considerable clinical results. Indeed, several clinical trials have reported durable clinical response in different tumor types, such as melanoma, renal cell carcinoma (RCC) and non-small cell lung cancer (NSCLC). Nonetheless, after the initial enthusiasm, it is now evident that the majority of patients do not benefit from ICIs, due to innate or acquired tumor resistance. It is therefore mandatory to find ways to identify those patients who will respond and to find ways to induce response in those who at present do not benefit from ICIs. In this regard, the expression of programmed death ligand 1 (PD-L1) on neoplastic cells was the first, and most obvious, biomarker exploited to predict the activity of anti-programmed death 1 (PD-1) and/or anti-PD-L1 antibodies. As expected, a correlation was confirmed between the levels of PD-L1 and the efficacy of anti-PD-1 therapy in melanoma, NSCLC and RCC. However, further results from clinical trials showed that some patients display a clinical response regardless of tumor cell PD-L1 expression levels, while others do not benefit from ICI treatment despite the expression of PD-L1 on neoplastic elements. These findings strongly support the notion that other factors may be relevant for the efficacy of ICI-based treatment regimens. Furthermore, although the current dogma indicates that the PD-1/PD-L1 axis exerts its regulatory effects via the signal transduced in PD-1-expressing T cells, recent evidence suggests that a reverse signaling may also exist downstream of PD-L1 in both tumor and immune cells. The reverse signaling of PD-L1, but also of other immune checkpoints, might contribute to the pro-tumoral/immune suppressive environment associated with tumor development and progression. Clarifying this aspect could facilitate the prediction of patients’ clinical outcomes, which are so far unpredictable and result in response, resistance or even hyper-progressive disease in some cases. Full article
(This article belongs to the Special Issue Signaling Pathways and Immune Checkpoint Regulation in Cancer)
Show Figures

Figure 1

Open AccessEditor’s ChoiceReview
Immunotherapy Associated Pulmonary Toxicity: Biology Behind Clinical and Radiological Features
Cancers 2019, 11(3), 305; https://0-doi-org.brum.beds.ac.uk/10.3390/cancers11030305 - 05 Mar 2019
Cited by 26 | Viewed by 2567
Abstract
The broader use of immune checkpoint blockade in clinical routine challenges clinicians in the diagnosis and management of side effects which are caused by inflammation generated by the activation of the immune response. Nearly all organs can be affected by immune-related toxicities. However, [...] Read more.
The broader use of immune checkpoint blockade in clinical routine challenges clinicians in the diagnosis and management of side effects which are caused by inflammation generated by the activation of the immune response. Nearly all organs can be affected by immune-related toxicities. However, the most frequently reported are: fatigue, rash, pruritus, diarrhea, nausea/vomiting, arthralgia, decreased appetite and abdominal pain. Although these adverse events are usually mild, reversible and not frequent, an early diagnosis is crucial. Immune-related pulmonary toxicity was most frequently observed in trials of lung cancer and of melanoma patients treated with the combination of the anti-cytotoxic T lymphocyte antigen (CTLA)-4 and the anti-programmed cell death-1 (PD-1) antibodies. The most frequent immune-related adverse event in the lung is represented by pneumonitis due to the development of infiltrates in the interstitium and in the alveoli. Clinical symptoms and radiological patterns are the key elements to be considered for an early diagnosis, rendering the differential diagnosis crucial. Diagnosis of immune-related pneumonitis may imply the temporary or definitive suspension of immunotherapy, along with the start of immuno-suppressive treatments. The aim of this work is to summarize the biological bases, clinical and radiological findings of lung toxicity under immune checkpoint blockade, underlining the importance of multidisciplinary teams for an optimal early diagnosis of this side effect, with the aim to reach an improved patient care. Full article
(This article belongs to the Special Issue Signaling Pathways and Immune Checkpoint Regulation in Cancer)
Show Figures

Figure 1

Back to TopTop