Excluding T Cells: Is β-Catenin the Full Story?

Wnt/β-catenin inhibitor ICG-001 enhances the antitumor efficacy of radiotherapy by increasing radiation-induced DNA damage and improving tumor immune microenvironment in hepatocellular carcinoma

BACKGROUND AND PURPOSE

Radiotherapy (RT) has a promising anti-tumor effect depending on its effects on both cancer cells and tumor immune microenvironment (TIME). As one of the most common alterations in hepatocellular carcinoma (HCC), wnt/β-catenin pathway activation, has been reported to induce radioresistance and suppressive TIME. In this study, we aim to explore the effect of wnt/β-catenin inhibitor ICG-001 on radiosensitivity and RT-related TIME of HCC and the underlying mechanism.

MATERIALS AND METHODS

C57BL/6 and nude mouse tumor models were used to evaluate the efficacy of different treatments on tumor growth, recurrence and mice survival. Flow cytometry was performed to assess tumor infiltrating lymphocytes (TILs). DNA damage response (DDR) and radioresistance was investigated by colony formation assays, γ-H2AX and micronuclei measurements.

RESULTS

The addition of ICG-001 to RT exhibited better anti-tumor and survival-prolong efficacy in C57BL/6 than nude mice. TILs analysis revealed that ICG-001 plus RT boosted the infiltration and IFN-γ production of TIL CD8⁺ T cells, meanwhile reduced the number of Tregs. Moreover, mechanistic study demonstrated that ICG-001 increased the radiation-induced DDR of HCC cells by suppressing p53, thus leading to stronger activation of cGAS/STING pathway. Utilization of cGAS/STING pathway inhibitors impaired the therapeutic effect of combination therapy. Furthermore, combination therapy led to stronger immunologic memory and tumor relapse prevention.

CONCLUSIONS

Our findings showed that ICG-001 displayed both local and systematic effects by increasing radiosensitivity and improving immunity in HCC, which indicated that ICG-001 might be a potential synergetic treatment for radiotherapy and radioimmunotherapy in HCC patients.

Mechanisms of resistance to immune checkpoint inhibitors and strategies to reverse drug resistance in lung cancer

In recent years, the research of immune checkpoint inhibitors has made a great breakthrough in lung cancer treatment. Currently, a variety of immune checkpoint inhibitors have been applied into clinical practice, including antibodies targeting the programmed cell death-1, programmed cell death-ligand 1, and cytotoxic T-lymphocyte antigen 4, and so on. However, not all patients can benefit from the treatment. Abnormal antigen presentation, functional gene mutation, tumor microenvironment, and other factors can lead to primary or secondary resistance. In this paper, we reviewed the molecular mechanism of immune checkpoint inhibitor resistance and various combination strategies to overcome resistance, in order to expand the beneficial population and enable precision medicine.

Outcome-Related Signatures Identified by Whole Transcriptome Sequencing of Resectable Stage III/IV Melanoma Evaluated after Starting Hu14.18-IL2

PURPOSE

We analyzed whole transcriptome sequencing in tumors from 23 patients with stage III or IV melanoma from a pilot trial of the anti-GD2 immunocytokine, hu14.18-IL2, to identify predictive immune and/or tumor biomarkers in patients with melanoma at high risk for recurrence.

EXPERIMENTAL DESIGN

Patients were randomly assigned to receive the first of three monthly courses of hu14.18-IL2 immunotherapy either before (Group A) or after (Group B) complete surgical resection of all known diseases. Tumors were evaluated by histology and whole transcriptome sequencing.

RESULTS

Tumor-infiltrating lymphocyte (TIL) levels directly associated with relapse-free survival (RFS) and overall survival (OS) in resected tumors from Group A, where early responses to the immunotherapy agent could be assessed. TIL levels directly associated with a previously reported immune signature, which associated with RFS and OS, particularly in Group A tumors. In Group A tumors, there were decreased cell-cycling gene RNA transcripts, but increased RNA transcripts for repair and growth genes. We found that outcome (RFS and OS) was directly associated with several immune signatures and immune-related RNA transcripts and inversely associated with several tumor growth-associated transcripts, particularly in Group A tumors. Most of these associations were not seen in Group B tumors.

CONCLUSIONS

We interpret these data to signify that both immunologic and tumoral cell processes, as measured by RNA-sequencing analyses detected shortly after initiation of hu14.18-IL2 therapy, are associated with long-term survival and could potentially be used as prognostic biomarkers in tumor resection specimens obtained after initiating neoadjuvant immunotherapy.

Immune Checkpoint Inhibitors: Basics and Challenges

Cancer is one of the most deadly diseases in the modern world. The last decade has witnessed dramatic advances in cancer treatment through immunotherapy. One extremely promising means to achieve anti-cancer immunity is to block the immune checkpoint pathways - mechanisms adopted by cancer cells to disguise themselves as regular components of the human body. Many review articles have described a variety of agents that are currently under extensive clinical evaluation. However, while checkpoint blockade is universally effective against a broad spectrum of cancer types and is mostly unrestricted by the mutation status of certain genes, only a minority of patients achieve a complete response. In this review, we summarize the basic principles of immune checkpoint inhibitors in both antibody and smallmolecule forms and also discuss potential mechanisms of resistance, which may shed light on further investigation to achieve higher clinical efficacy for these inhibitors.

Cancer immunoediting and resistance to T cell-based immunotherapy

Anticancer immunotherapies involving the use of immune-checkpoint inhibitors or adoptive cellular transfer have emerged as new therapeutic pillars within oncology. These treatments function by overcoming or relieving tumour-induced immunosuppression, thereby enabling immune-mediated tumour clearance. While often more effective and better tolerated than traditional and targeted therapies, many patients have innate or acquired resistance to immunotherapies. Cancer immunoediting is the process whereby the immune system can both constrain and promote tumour development, which proceeds through three phases termed elimination, equilibrium and escape. Throughout these phases, tumour immunogenicity is edited, and immunosuppressive mechanisms that enable disease progression are acquired. The mechanisms of resistance to immunotherapy seem to broadly overlap with those used by cancers as they undergo immunoediting to evade detection by the immune system. In this Review, we discuss how a deeper understanding of the mechanisms underlying the cancer immunoediting process can provide insight into the development of resistance to immunotherapies and the strategies that can be used to overcome such resistance.

β-Catenin-driven adrenocortical carcinoma is characterized with immune exclusion

Aim

Adrenocortical carcinoma (ACC) is characterized by overexpressed CTNNB1, which is reported to modulate immune exclusion. Cross talk between CTNNB1 and cancer immunity in ACC remains unclear.

Materials and methods

In silico reproduction of TCGA-ACC dataset (N = 92) and external validation using tissue samples were performed (N = 16). Expression data of CTNNB1, PD-1, and PD-L1 were extracted in silico and tumor-infiltrating lymphocytes (TILs) were profiled using code provided by Tumor IMmune Estimation Resource (TIMER). In-house formalin-fixed paraffin-embedded ACC samples were processed using immunohistochemical (IHC) staining for CTNNB1, CD45, PD-1, and PD-L1.

Results

Increased CTNNB1 expression was significantly associated with worsened overall survival (OS) (P = 0.006). CD8⁺ cells were significantly associated with better OS (P = 0.02). Higher PD-L1 (P = 0.019), but not PD-1 expression (P = 0.325), was associated with better OS. CTNNB1 overexpression was significantly associated with increased tumor purity (r = 0.356, P = 0.002) and fewer TILs (r = -0.833, P = 0.029), decreased infiltrating CD8⁺ cells (P = 0.033), and increased infiltrating B cells (P = 0.026). CTNNB1 expression was negatively correlated with PD-L1 expression (r = -0.308, P = 0.006) but not with PD-1 expression (P = 0.067), which were externally validated (P = 0.032 for PD-L1 and P = 0.400 for PD-1). The Cox regression model encompassing gender, B cells, CD8⁺ cells, PD-L1, CTNNB1, and Ki-67 revealed that only Ki-67 overexpression remained significantly associated with OS (P < 0.001), while CTNNB1 showed marginal significance (P = 0.06). CTNNB1-overexpressed patients were more likely to have cortisol excess (P = 0.003).

Conclusion

ACC with CTNNB1 overexpression is associated with poor prognosis and decreased immunity. Our findings suggest that CTNNB1-targeting therapy may overcome immune exclusion in ACC.

The regulation of β-catenin activity and function in cancer: therapeutic opportunities

Wnt/β-catenin signaling is an evolutionarily conserved and versatile pathway that is known to be involved in embryonic development, tissue homeostasis and a wide variety of human diseases. Aberrant activation of this pathway gives rise to the accumulation of β-catenin in the nucleus and promotes the transcription of many oncogenes such as c-Myc and CyclinD-1. As a result, it contributes to carcinogenesis and tumor progression of several cancers, including colon cancer, hepatocellular carcinoma, pancreatic cancer, lung cancer and ovarian cancer. β-Catenin is a pivotal component of the Wnt signaling pathway and it is tightly regulated at three hierarchical levels: protein stability, subcellular localization and transcriptional activity. Uncovering the regulatory mechanisms of β-catenin will provide new insights into the pathogenesis of cancer and other diseases, as well as new therapeutic strategies against these diseases. In this review we dissect the concrete regulatory mechanisms of β-catenin from three aspects mentioned above. Then we focus on the role of β-catenin in cancer initiation, progression, dormancy, immunity and cancer stem cell maintenance. At last, we summarize the recent progress in the development of agents for the pharmacological modulation of β-catenin activity in cancer therapy.

Infiltration of CD8 T Cells and Expression of PD-1 and PD-L1 in Synovial Sarcoma

Tumors expressing programmed death ligand 1 (PD-L1) interact with the corresponding negative-signal generating immune receptor on the surface of CD8 T cells, PD-1, thereby suppressing antitumor activity. Therapeutics blocking this interaction have shown promise in various cancers by restoring functional antitumor T-cell activity. We explored the degree of PD-L1, PD-1, and CD8 expression in a retrospective analysis of 29 clinical synovial sarcoma samples. Quantitative immunohistochemistry and multiplex immunofluorescence were used to determine relative quantification of CD8⁺ and PD-1⁺ T cells and PD-L1 expression within the intratumor area and the interface between the tumor and the surrounding nontumor tissue (i.e., invasive margin), and colocalization of these factors, respectively. PD-L1, PD-1, and CD8 cell densities in the tumor-invasive margins were significantly higher in the metastatic tumors than the primary tumors (P < 0.01), and PD-L1, PD-1, and CD8 cell densities were all significantly positively correlated with one other (P < 0.0001). PD-1 cell density in the tumor-invasive margin was significantly associated with worse progression-free survival. Multiplex immunofluorescence demonstrated coexpression of PD-1 and CD8 on lymphocytes within the invasive margin, as well as relative proximity between PD-1⁺ CD8 cells and PD-L1⁺ tumor cells. Our results provide a preclinical rationale for screening of patients with synovial sarcoma for the colocalization of CD8, PD-1, and PD-L1, which may be a marker for response to PD-1 blockade therapy. Cancer Immunol Res; 5(2); 118-26. ©2016 AACR.