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Immune Checkpoints as a Target for Colorectal Cancer Treatment.

ABSTRACT: Anti-tumor immunity is a new line of research for the treatment of patients with solid tumors. In this field, negative regulators of the immune system called immune checkpoints play a key role in limiting antitumor immunologic responses. For this reason, immune checkpoint-inhibiting agents, such as those directed against cytotoxic T-lymphocyte antigen 4 (CTLA-4) and programmed death-1 receptor (PD1) and its ligand PD-L1, have been developed as antitumor drugs, producing interesting results in preclinical and clinical studies. We present an updated review of the biological background and clinical development of immune checkpoint inhibitors in colorectal cancer (CRC). Early trial results on PD1 and PD-L1 blockade appear promising, especially in CRC patients with microsatellite instability (MSI). Clinical trials are ongoing to confirm these preliminary results, evaluate combination strategies and identify biomarkers to predict which patients are most likely to benefit from, or show resistance to, the effects of checkpoint inhibition.

SUBMITTER: Passardi A

PROVIDER: S-EPMC5486145 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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Immune Checkpoints as a Target for Colorectal Cancer Treatment.

Passardi Alessandro A Canale Matteo M Valgiusti Martina M Ulivi Paola P

International journal of molecular sciences 20170621 6

Anti-tumor immunity is a new line of research for the treatment of patients with solid tumors. In this field, negative regulators of the immune system called immune checkpoints play a key role in limiting antitumor immunologic responses. For this reason, immune checkpoint-inhibiting agents, such as those directed against cytotoxic T-lymphocyte antigen 4 (CTLA-4) and programmed death-1 receptor (PD1) and its ligand PD-L1, have been developed as antitumor drugs, producing interesting results in pr ...[more]

PMID: 28635639

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Project description:BackgroundIncreasing evidence supporting the role of immune checkpoint blockade in cancer management has been bolstered by recent reports demonstrating significant and durable clinical responses across multiple tumour types, including metastatic urothelial carcinoma (mUC). The majority of these results are achieved via blockade of the programmed death (PD) axis, which like CTLA-4 blockade permits T-cell activation and immune-mediated anti-tumour activity- essentially harnessing the patient's own immune system to mount an anti-neoplastic response. However, while clinical responses can be striking, our understanding of the biology of immune checkpoint blockade is only beginning to shed light on how to maximize and even improve patient outcomes with immune checkpoint blockade, especially in UC.MethodsWe performed a literature review for immune checkpoint blockade with a focus on rationale for checkpoint therapy and outcomes in UC. We also highlight the advances made in other tumour types, with a focus on the recent 2015 meeting of the American Society for Clinical Oncology.ResultsIn heavily pre-treated UC, trials are suggesting objective response rates above 30% . These impressive results are seen across multiple different tumour types, especially those with high burden of DNA level mutations. Identification of prognostic biomarkers is currently under investigation, in order to improve patient selection. Interestingly, response to PD-1 directed therapy is seen even in patients with no evidence of PD-1 positivity on immunohistochemistry. This has led to the development of enhanced biomarkers including assessing DNA mutation rates and immune gene signatures, to improve patient selection.ConclusionsImmune checkpoint blockade is an exciting cancer treatment modality which is demonstrating impressive clinical results across multiple tumour types. For UC, anti-PD directed therapy represents a much needed treatment in the metastatic, post chemotherapy context. Potential for these agents to have clinical utility in non-metastatic UC is still to be assessed.

Project description:Immune checkpoint inhibitors (ICIs) have become a promising area of research for cancer treatment. In addition to the well-known ICIs targeting PD-1/PD-L1, HLA-G/ILT-2/-4 is relatively new immune checkpoint that has been evaluated in early clinical trials in patients with advanced solid tumors. In this study, the expression of HLA-G (n=157), ILT-2/4 (n=82), and PD-L1 (n=70) in epithelial cell adhesion molecule (EpCAM)-positive colorectal cancer (CRC) cells was analyzed by multicolor flow cytometry, and the prognostic significance of these molecules was evaluated. In EpCAM+ CRC cells, the median percentages of HLA-G, ILT-2, ILT-4, and PD-L1 were 14.90%, 67.70%, 8.55% and 80.30%, respectively. In addition, a positive correlation was observed between them (all p<0.001). Higher levels of these immune checkpoint proteins are associated with lymph node metastasis. In addition to the AJCC stage (p=0.001), Kaplan-Meier survival analysis showed that higher levels of HLA-G (p=0.041), ILT-2 (p=0.060), ILT-4 (p<0.001), PD-L1 (p=0.012), HLA-GILT4 (p<0.001) and ILT-2ILT-4 (p<0.001) were significantly associated with shorter survival of CRC patients. When CRC patients were stratified by early and advanced AJCC stages, HLA-G levels were only related to the survival among CRC patients with early disease stage (p=0.024), while ILT-4 levels were significant for both CRC patients with early (p=0.001) and advanced (p=0.020) disease stages. Multivariate cox regression analysis revealed that advanced AJCC stage (HR=2.435; p=0.005) and higher ILT-4 levels (HR=2.198; p=0.063) were independent risk factors for poor outcomes in patients with CRC. In summary, among the immune checkpoints, HLA-G/ILT-2/4 and PD-L1, ILT-4 is the most significant prognostic indicator of CRC. This finding indicated that a combination of immunotherapy strategies, such as ILT-4 blockade, could improve the clinical outcomes in patients with cancer. Moreover, multicolor flow cytometry can be employed as a reliable and efficient, alternative to immunohistochemistry, for evaluating the immune checkpoint proteins expressed in tumor lesions.

Project description:BackgroundMicrosatellite unstable colorectal cancers (MSI+ CRCs) expressing PD-L1, respond to anti-PD-1 or anti-PD-L1 checkpoint blockade, whereas microsatellite-stable tumors do not respond the same. Our aim was to examine how the immune landscape relates to different aspects of the CRC's biology, including neoepitope burden.MethodsWe used TCGA data to stratify patients based on a cytolytic T-cell activity expression index and correlated immune cytolytic activity (CYT) with mutational, structural, and neoepitope features of each tumor sample. The expression of several immune checkpoints was verified in an independent cohort of 72 CRC patients, relative to their MSI status, using immunohistochemistry and RT-qPCR.ResultsCRC exhibits a range of intertumoral cytolytic T-cell activity, with lower cytolytic levels in the tumor, compared to the normal tissue. We separated CRC patients into CYT-high and CYT-low subgroups. High cytolytic activity correlated with increased mutational load in colon tumors, the count of MHC-I/-II classically defined and alternatively defined neoepitopes, high microsatellite instability and deregulated expression of several inhibitory immune checkpoints (VISTA, TIGIT, PD-1, IDO1, CTLA-4, and PD-L1, among others). Many immune checkpoint molecules (IDO1, LAG3, TIGIT, VISTA, PD-1, PD-L1 and CTLA-4) expressed significantly higher in MSI+ CRCs compared to MSS tumors. The expression of Treg markers was also significantly higher in CYT-high tumors. Both individual and simultaneous high levels of CTLA-4 and PD-L1 had a positive effect on the patients' overall survival. On the reverse, simultaneous low expression of both genes led to a significant shift towards negative effect. Assessed globally, CYT-low CRCs contained more recurrent somatic copy number alterations. PD-L1 protein was absent in most samples in the independent cohort and stained lowly in 33% of MSI CRCs. PD-L1+ CRCs stained moderately for CD8 and weakly for FOXP3. CYT-high colon tumors had higher TIL load, whereas CYT-high rectum tumors had higher TAN load compared to their CYT-low counterparts.ConclusionsOverall, we highlight the link between different genetic events and the immune microenvironment in CRC, taking into consideration the status of microsatellite instability. Our data provide further evidence that MSI+ and CYT-high tumors are better candidates for combinatorial checkpoint inhibition.

Dataset Information

Immune Checkpoints as a Target for Colorectal Cancer Treatment.

Publications

Immune Checkpoints as a Target for Colorectal Cancer Treatment.

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