Heterogeneity of programmed death‐ligand expression in a case of Merkel cell carcinoma exhibiting complete regression after multiple metastases

Tumor immune microenvironment of cutaneous angiosarcoma with cancer testis antigens and the formation of tertiary lymphoid structures

Cutaneous angiosarcoma (CAS) is a highly malignant tumor with few effective treatments. Although the indication for immune checkpoint inhibitors such as anti-PD-1 antibodies is expected to expand, there are many unknowns regarding the tumor immune microenvironment in CAS, which is generally considered an immunologically “cold” tumor. Our previous study demonstrated that tertiary lymphoid structures (TLSs) were associated with a favorable prognosis in CAS. However, we still don’t know what the difference is between cases of TLS-rich and TLS-poor. Furthermore, the number of TLSs can vary significantly between lesions in the same case, for example, between primary and recurrence. To analyze the changes in the tumor immune microenvironment in CAS in more detail, we performed comprehensive RNA sequencing using a Next-generation sequencer (NGS). Sixty-two samples from 31 cases of CAS treated at Nagoya City University were collected. NGS and gene set enrichment analysis (GSEA) were performed on 15 samples among them. Immunohistochemistry and prognostic analysis by Kaplan-Meier method were performed on all 62 samples. NGS results showed that NY-ESO-1 (CTAG1B) was significantly upregulated in the TLS-positive cases. Immune checkpoint molecules including programmed death-1 (PD-1) and programmed death-ligand 1 (PD-L1) were upregulated in TLS-negative or TLS-low cases and seemed to associate with the suppression of TLS formation. In a comparison of primary and recurrent lesions, other cancer-testis antigens (CTAs) including XAGE-1B were significantly upregulated in recurrent lesions. The number of infiltrating CD8-positive cells and TLSs showed no significant trend between primary and recurrent lesions. However, the PD-L1 expression of tumor cells was significantly lower in recurrent than in primary lesions. Chemokines correlated with NY-ESO-1 expression were CCL21 and CXCL8, and only CCL21 correlated with the number of TLS. There was no chemokine associated with XAGE-1. NY-ESO-1 and XAGE-1 are detectable by immunohistochemistry. Although each cannot be a prognostic marker by itself, they can be a helpful marker in combination with the number of TLSs. CTAs play an essential role in forming the tumor immune microenvironment in CAS. These findings are evidence that CAS is an immunologically “hot” tumor and provides us with potential therapeutic targets and encourages the expansion of immunotherapy indications.

Differences in the immune microenvironment between improved and non-improved cases of vitiligo after halo nevus excision

BACKGROUND

Halo nevus, also called Sutton's nevus, is a nevus cell nevus surrounded by vitiligo thought to be caused by a T-cell mediated immune response to the nevus antigen. The immune microenvironment is mysterious, however, as vitiligo often does not improve even when the nevus cells are removed.

OBJECTIVES

To analyze the clinical course and immune microenvironment of patients with halo nevus who had undergone nevus excision.

METHODS

We collected 54 halo nevus patients and performed multivariate analysis and immunohistochemical analysis, including multiplexed immune cell phenotyping and spatial single-cell analyses using the PhenoCycler® assay.

RESULTS

Multivariate analysis revealed that only the presence or absence of vitiligo vulgaris at the time of consultation was associated with improvement in the surrounding vitiligo following excision. Expression of programmed death-ligand 1 in nevus cells was significantly higher in non-improved cases compared with improved cases. The PhenoCycler® assay revealed that CD107a-positive and CD21-positive cells were more prevalent in improved cases than in non-improved cases. In the improved cases, active cell-cell interactions, centered on CD21-positive cells, were observed, whereas in the non-improved cases, cell-cell interactions were sparse. Instead, a dense infiltration of CD8-positive cells and CD3 and CD4-positive cells was observed in non-improved cases.

CONCLUSION

Elucidation of the immune microenvironment of halo nevus is also relevant to melanoma-associated vitiligo and will contribute to our understanding of tumor immunity.

Tertiary Lymphoid Structures and Chemokine Landscape in Virus-Positive and Virus-Negative Merkel Cell Carcinoma

Tertiary lymphoid structures (TLSs) are used as biomarkers in many cancers for predicting the prognosis and assessing the response to immunotherapy. In Merkel cell carcinoma (MCC), TLSs have only been examined in MCPyV-positive cases. Here, we examined the prognostic value of the presence or absence of TLSs in 61 patients with MCC, including MCPyV-positive and MCPyV-negative cases. TLS-positive samples had a significantly better prognosis than TLS-negative samples. MCPyV-positive samples had a good prognosis with or without TLSs, and MCPyV-negative/TLS-positive samples had a similarly good prognosis as MCPyV-positive samples. Only MCPyV-negative/TLS-negative samples had a significantly poor prognosis. All cases with spontaneous regression were MCPyV-positive/TLS-positive. We also performed a comprehensive analysis of the chemokines associated with TLS formation using next-generation sequencing (NGS). The RNA sequencing results revealed 5 chemokine genes, CCL5, CCR2, CCR7, CXCL9, and CXCL13, with significantly high expression in TLS-positive samples compared with TLS-negative samples in both MCPyV-positive and MCPyV-negative samples. Only 2 chemokine genes, CXCL10 and CX3CR1, had significantly different expression levels in the presence or absence of MCPyV infection in TLS-negative samples. Patients with high CXCL13 or CCL5 expression have a significantly better prognosis than those with low expression. In conclusion, the presence of TLSs can be a potential prognostic marker even in cohorts that include MCPyV-negative cases. Chemokine profiles may help us understand the tumor microenvironment in patients with MCPyV-positive or MCPyV-negative MCC and may be a useful prognostic marker in their own right.

Immune activity in Merkel cell carcinoma

Merkel cell carcinoma (MCC) is widely known as a highly malignant skin cancer. The pathogenesis of MCC, however, remains mysterious due to the extremely small number of cases and its prevalence in the elderly. Despite its high‐grade malignancy, spontaneous regression occurs with some frequency. The immune activity of the tumor underlies this peculiar behavior. In recent years, immune checkpoint blockade therapies, including the anti‐programmed death ligand 1 antibody, have provided successful results. These therapies, however, are ineffective in approximately half the patients with advanced MCC and few treatments are available for those patients. In this review, we summarize the increasing body of evidence relating to the immune activity of MCC and immunological biomarkers. The interesting and sometimes peculiar behavior of MCC, such as their spontaneous regression, is largely due to their high immunosensitivity. Understanding the tumor immunokinetics of MCC should provide critical insight for understanding cancer immunotherapy. Here, we introduce a new classification for MCC according to its immune activity. Combined application of programmed death ligand 1 (a prognostic factor and predictor of the efficacy of immune checkpoint inhibitors in various cancers) with glucose‐6‐phosphate dehydrogenase (a new promising biomarker for MCC) may enable classification of MCC based on its immune status. Whether the new classification can be used to predict the efficacy of immune checkpoint blockade therapies remains to be evaluated in future studies, but the classification may facilitate future treatment selection.

Glucose-6-phosphate dehydrogenase correlates with tumor immune activity and programmed death ligand-1 expression in Merkel cell carcinoma

Background

Merkel cell carcinoma (MCC) is a rare and highly malignant skin cancer. Some cases have a good prognosis and spontaneous regression can occur. Reported prognostic markers, such as Merkel cell polyoma virus infection or programmed death ligand-1 (PD-L1) expression, remain insufficient for precisely estimating the vastly different patient outcomes. We performed RNA sequencing to evaluate the immune response and comprehensively estimate prognostic values of immunogenic factors in patients with MCC.

Methods

We collected 90 specimens from 71 patients and 53 blood serum samples from 21 patients with MCC at 10 facilities. The mRNA was extracted from formalin-fixed paraffin-embedded tissues. Next-generation sequencing, immunohistochemical staining and blood serum tests were performed.

Results

Next-generation sequencing results classified MCC samples into two types: the ‘immune active type’ was associated with better clinical outcomes than the ‘cell division type’. Expression of the glucose-6-phosphate dehydrogenase (G6PD) gene was highly significantly upregulated in the ‘cell division type’. Among 395 genes, G6PD expression correlated with the presence of lymph node or distant metastases during the disease course and significantly negatively correlated with PD-L1 expression. Immunohistochemical staining of G6PD also correlated with disease-specific survival and exhibited less heterogeneity compared with PD-L1 expression. G6PD activity could be measured by a blood serum test. The detection values significantly increased as the cancer stage progressed and significantly decreased after treatment.

Conclusions

G6PD expression was an immunohistochemically and serum-detectable prognostic marker that negatively correlated with immune activity and PD-L1 levels, and could be used to predict the immunotherapy response.