Extracellular signal-regulated kinase activation of self-healing Langerhans cell histiocytosis: A case report.

A 3-month-old boy developed small papules on his trunk. After the papules increased in number, the patient was diagnosed with Langerhans cell histiocytosis based on the pathological findings. He was referred to our department for further examination. Upon initial examination, the papules and nodules were scattered on his back, abdomen and lumbar region. Because he did not present with any organ involvement except the skin, he was diagnosed with single-system and skin-limited Langerhans cell histiocytosis. Skin rashes were treated with a topical steroid and started regressing 3 months after onset. All papules disappeared 6 months after onset. In this boy, the Langerhans cell histiocytosis tumor cells expressed phosphorylated extracellular signal-regulated kinases. In Langerhans cell histiocytosis, BRAF V600E and other genes are known to mutate to act as driver mutations in stem cells of the myeloid dendritic cell lineage. Consequently, extracellular signal-regulated kinases are continuously activated, which contributes to Langerhans cell histiocytosis carcinogenesis.

Spontaneous regression of malignant melanoma - is it based on the interplay between host immune system and melanoma antigens?

Malignant melanoma (MM) is the most aggressive and uneasily treatable form of skin cancer. Up to 90% of deaths because of skin tumours are estimated to be caused by this malignancy. Spontaneous regression is described as a partial or complete disappearance of cancer. It can be defined if the clinical and histological diagnosis of malignancy is verified and any therapeutic intervention potentially inducing mechanisms leading to regression has not been applied. Regression occurs more frequently in melanoma than in other types of tumours; it is reported to be six times higher than in other malignancies. Up to 50% of primary MM is reported to undergo spontaneous regression. However, spontaneous regression of the metastatic form of tumour is a rare phenomenon observed in only 0.23% of cases. The most frequently mentioned factors leading to spontaneous regression of MM are operative trauma, infection, vaccination (BCG and rabies vaccines) and immunological factors. Other well-documented circumstances associated with regression of metastatic MM include blood transfusion and various endocrine factors.

Spontaneous regression of hepatocellular carcinoma: A mini-review.

Spontaneous tumor regression is an extremely rare phenomenon in the oncology field. However, there are several case reports resulted in the regression of hepatocellular carcinoma (HCC) and the accumulation of clinical information and analyses of the mechanism can contribute to the development of a novel therapy. For this purpose, we have carefully reviewed 23 cases of spontaneously regressed HCC published in recent 5 years and our case. The information regarding the tumor size, tumor marker, treatments, etc., have been summarized. The mechanism of spontaneous regression has been discussed to date and presumed to be due to many factors, including hypoxia and immunological reactions. In this careful review of the 24 cases based on the clinical information, hypoxia, systemic inflammation, and both upon spontaneous regression were seen in 3, 8, and 4 cases, respectively among the 15 cases for which the information regarding the proposed mechanisms are available. Recent development of immunotherapeutic approaches in oncology shows promising results, therefore, accumulation of additional cases and analysis of mechanisms underlying the spontaneous regression of HCC are essential and could lead to the development of a new generation of immunotherapies including antibodies directed against immune reactions.

Therapeutic benefit of Salmonella attributed to LPS and TNF-α is exhaustible and dictated by tumor susceptibility.

The potential of bacteria-mediated tumor therapy (BMTT) is highlighted by more than a century of investigation. Attenuated Salmonella has prevailed as promising therapeutic agents. For BMTT - categorized as an immune therapy - the exact contribution of particular immune reactions to the therapeutic effect remains ambiguous. In addition, one could argue for or against the requirement of bacterial viability and tumor targeting. Herein we evaluate the isolated therapeutic efficacy of purified LPS and TNF-α, which together account for a dominant immunogenic pathway of gram negative bacteria like Salmonella. We show that therapeutic efficacy against CT26 tumors does not require bacterial viability. Analogous to viable Salmonella SL7207, tumor regression by a specific CD8+ T cell response can be induced by purified LPS or recombinant TNF-α (rTNF-α). Conversely, therapeutic effects against RenCa tumors were abrogated upon bacterial avitalization and limited using isolated adjuvants. This argues for an alternative mechanistic explanation for SL7207 against RenCa that depends on viability and persistence. Unable to boost bacterial therapies by co-injection of rTNF-α suggested therapeutic effects along this axis are exhausted by the intrinsic adjuvanticity of bacteria alone. However, the importance of TNF-α for BMTT was highlighted by its support of tumor invasion and colonization in concert with lower infective doses of Salmonella. In consideration, bacterial therapeutic effectiveness along the axis of LPS and TNF-α appears limited, and does not offer the necessary plasticity for different tumors. This emphasizes a need for recombinant strengthening and vehicular exploitation to accommodate potency, plasticity and distinctiveness in BMTT.

The microenvironment in primary cutaneous melanoma with associated spontaneous tumor regression: evaluation for T-regulatory cells and the presence of an immunosuppressive microenvironment.

Spontaneous tumor regression, regression in the absence of therapeutic intervention, can be identified histologically in over 25% of primary cutaneous melanomas at initial diagnosis. A unique subset of T lymphocytes found in areas of regression can be histologically distinguished from tumor-infiltrating T lymphocytes (TIL) found in areas of tumor progression. We call this unique subset of T lymphocytes regression-associated T lymphocytes (RATs). The aim of this study is to determine the phenotype of lymphocytes and the density of specific cell types linked to immunosuppression in areas of tumor progression compared with areas of tumor regression. These specific cell types include T-regulatory cells (Tregs) and S100A9 cells. A total of 14 primary cutaneous melanomas with areas of progression and regression were used. Immunohistochemistry staining was used to identify CD4 cells, CD8 cells, Tregs, and S100A9 cells. Two independent observers manually counted three high-powered ×40 fields. There was no predominance of CD4 or CD8 T lymphocytes in either RATs or TIL. We identified a lower density of Tregs in RATs compared with TIL when using the FOXP3/CD4 Treg marker (P=0.04) and a marginal difference when using our second, confirmatory Treg marker, FOXP3/CD25 (P=0.11). We observed a lower density of S100A9 cells in RATs compared with TIL (P=0.002). There was an observable difference in the tumor microenvironments of RATs and TIL, with RATs having a significantly lower density of Tregs and S100A9 cells. We deduce that the absence of immunosuppression in areas of regression allows for a more robust immune response and thus effective eradication of tumor cells.

Spontaneous Involution of Congenital Melanocytic Nevus With Halo Phenomenon.

Congenital melanocytic nevus (CMN) is a neural crest-derived hamartoma, which appear at or soon after birth. CMN has a dynamic course and may show variable changes over time, including spontaneous involution. Spontaneous involution of CMN is a rare phenomenon and is often reported in association with halo phenomenon or vitiligo. The mechanism of halo phenomenon is yet to be investigated but is suggested to be a destruction of melanocytes by immune responses of cytotoxic T cells or IgM autoantibodies. Here, the authors report an interesting case of spontaneously regressed medium-sized CMN with halo phenomenon and without vitiligo, which provides evidence that cytotoxic T cells account for the halo formation and pigmentary regression of CMN.

Current concepts of immune based treatments for patients with HCC: from basic science to novel treatment approaches.

The recent approval of two immune checkpoint inhibitors for the treatment of malignant melanoma has sparked great interest by physicians and basic scientists searching for novel therapeutics for GI cancer. Chronic inflammation is recognised as a major risk factor for the development of hepatocellular carcinoma (HCC) and makes this type of cancer a potentially ideal target for an immune based treatment approach. Further evidence for a critical role of immune responses in patients with HCC is derived from the fact that immune signatures and profiles predict patients' outcome as well as the fact that tumour-induced spontaneous antitumour immunity can be detected. In addition ablative therapies can lead to changes in the number, phenotype and function of different immune cell subsets, which correlate with patients' survival. Various HCC-specific mouse models have been developed, which improve our understanding of hepatocarcinogenesis and tumour-immune cell interactions, and lead to the development of novel immune based treatment approaches, which are currently being evaluated in preclinical and in early clinical settings. Immune checkpoint blockade along with adoptive immune cell therapy and vaccine approaches are currently being evaluated either alone or in combination with other treatments. Here, we provide an overview for the rationale of immunotherapy in HCC, summarise ongoing studies and provide a perspective for immune based approaches in patients with HCC.

Spontaneous regression of breast cancer with axillary lymph node metastasis: a case report and review of literature.

Spontaneous regression (SR) of cancer is a rare but well-documented biological phenomenon. However, the mechanism remains to be elucidated. We herein report a case of the SR of breast cancer at both the primary site and metastatic axillary lymph node with spontaneously-induced T cell-mediated immunological responses. A 52-year-old female with a lump in the left axilla was diagnosed to have a small breast carcinoma with a distinct axillary lymph node metastasis. During the preoperative systemic examination, she was diagnosed to have severe type 2 diabetes mellitus, was treated with insulin, and the hyperglycemia was normalized after one month. Surgery for left breast cancer was then performed. The postoperative histopathological examination revealed the SR of breast cancer at both the primary site and metastatic axillary lymph node. Immunohistochemical studies revealed that estrogen receptor positive, AE1/AE3-positive ductal carcinoma completely underwent necrosis associated with extensive infiltration of CD3-positive T cells in the tumor nodule in the lymph node. In addition, primary ductal carcinoma cells also underwent single cell necrosis with infiltration of T cells with lymph follicle-like organization of B cells in the mammary gland. The features were suggestive that the tumor eradication in the metastatic lymph node and regression of the primary ductal carcinoma could be due to host T cell response to the ductal carcinoma. As far as we know it is the first report that shows the spontaneous regression of breast cancer, probably due to the spontaneously-induced T cell response.

Assessment of regression in successive primary melanomas.

INTRODUCTION AND OBJECTIVES: It has been suggested that patients who have had a melanoma may develop increased immunity against certain antigens expressed by tumor-associated melanocytes. Thus our objective was to review the records of patients with successive primary melanomas to ascertain whether the pattern of regression might indicate the presence of an immunization effect arising from the first melanoma. MATERIAL AND METHODS: A review of all the cases recorded in the melanoma database of our dermatology department between 2000 and 2012 identified 19 patients who had multiple asynchronous melanomas (2.56% of all the cases recorded). We studied the presence or absence of regression in these melanomas and other clinical and histological characteristics. RESULTS: The presence of regression was significantly higher in successive melanomas than in the first tumors identified (42.10% vs 21.05%, P=.018). Regression of at least 1 melanoma was observed in 42.10% of the patients studied and regression of 2 melanomas was observed in 21.05%. In no case was regression observed in the first melanoma and not in the second; however, in 21.05% of the patients there was evidence of regression in the second tumor and none in the first. CONCLUSIONS: Our findings suggest the possibility that the first melanoma produces an immunization effect in some patients who develop multiple asynchronous melanomas.

Spontaneous regression of metastatic melanoma - clinical evidence of the abscopal effect.

INTRODUCTION: Metastatic melanoma is poorly understood. Regression of primary lesions has been associated with poor prognosis, but spontaneous regression of all metastatic disease is clearly beneficial. A patient's own immune responses occasionally appear to stimulate spontaneous regression of metastatic disease in melanoma. PATIENTS AND METHODS: We present six interesting cases of complete or nearly complete spontaneous regression of metastatic melanoma, suggest possible causes and review the literature. RESULTS AND CONCLUSIONS: These cases show clear radiological, pathological or clinical evidence of spontaneous regression of metastatic melanoma. This remains a poorly understood phenomena warranting further investigation and may prove useful in the development of immune mediated solutions.

Immunohistochemical and immunoelectron study of major histocompatibility complex class-II antigen in canine cutaneous histiocytoma: its relation to tumor regression.

In order to investigate the immune mechanisms involved in regression of canine cutaneous histicytoma (CCH), major histocompatibility complex (MHC) class-II immuno-expression and the number of T- and B-lymphocytes and macrophages were analyzed in 93 cases of CCH. MHC class-II was also studied in 16 cases of CCH by immunoelectron microscopy. All tumors expressed MHC class-II, and two major staining patterns were identified: focal juxtanuclear cytoplasmic staining and rim-like staining along the cell periphery. The MHC class-II labelling pattern and T- and B-lymphocyte infiltrates were associated with tumor regression. In regressing lesions, MHC class-II molecules shift to the cell surface and an increase of both T- and B-lymphocytes were noted. The increasing expression of MHC class-II molecules on the cell surface could be a significant factor for the onset and progression of tumour regression.

ATM-dependent spontaneous regression of early Eµ-myc-induced murine B-cell leukemia depends on natural killer and T cells.

Mechanisms of spontaneous tumor regression have been difficult to characterize in a systematic manner due to their rare occurrence and the lack of model systems. Here, we provide evidence that early-stage B cells in Eµ-myc mice are tumorigenic and sharply regress in the periphery between 41 and 65 days of age. Regression depended on CD4(+), CD8(+), NK1.1(+) cells and the activation of the DNA damage response, which has been shown to provide an early barrier against cancer. The DNA damage response can induce ligands that enhance immune recognition. Blockade of DNAM-1, a receptor for one such ligand, impaired tumor regression. Hence, Eµ-myc mice provide a model to study spontaneous regression and possible mechanisms of immune evasion or suppression by cancer cells.

The prevalence of cervical regulatory T cells in HPV-related cervical intraepithelial neoplasia (CIN) correlates inversely with spontaneous regression of CIN.

PROBLEM: Local adaptive cervical regulatory T cells (Tregs) are the most likely direct suppressors of the immune eradication of cervical intraepithelial lesion (CIN). PD-1 expression on T cells induces Tregs. No studies have quantitatively analyzed the Tregs and PD-1+ cells residing in CIN lesions. METHOD OF STUDY: Cervical lymphocytes were collected using cytobrushes from CIN patients and analyzed by FACS analysis. Comparisons were made between populations of cervical Tregs and PD-1+ CD4+ T cells in CIN regressors and non-regressors. RESULTS: A median of 11% of cervical CD4+ T cells were Tregs, while a median of 30% were PD-1+ cells. The proportions of cervical CD4+ T cells that were Tregs and/or PD-1+ cells were significantly lower in CIN regressors when compared with non-regressors. CONCLUSIONS: The prevalence of cervical tolerogenic T cells correlates inversely with spontaneous regression of CIN. Cervical Tregs may play an important role in HPV-related neoplastic immunoevasion.

Gene-expression profiling to identify genes related to spontaneous tumor regression in a canine cancer model.

Microarray transcriptome study in cancer has been commonly used to investigate tumorigenic mechanisms. The unique growth pattern of spontaneous regression (SR) after progressive (P) growth in canine transmissible venereal tumor (CTVT) provides a valuable cancer model to study the genome-wide differences in samples between the two stages of growth. In this study, Affymetrix analysis was performed based on the canine genome to compare the gene expression profiles of CTVT P- and SR-phase tumors. A total of 459 (278 up-regulated and 181 down-regulated) genes were identified as being differentially-expressed during the SR phase by the 2-fold method. Further analysis of these genes revealed that the expression of three genes associated with IL-6 production -TIMD-4, GPNMB and PLTP - was significantly higher in SR-phase tumors than in P-phase tumors; these results were also confirmed by real time RT-PCR in tumor tissues of beagles. In addition, we found that Th17-related genes were over-expressed in the SR phase, suggesting autoimmune responses involvement in tumor regression. Although the interaction between CTVT and host immunity were partially investigated in previous studies, our results enable us to gain new insight into the genes and possible mechanisms involved in tumor regression and reveal potentially useful targets for cancer therapy.