Anomalous diffusion of synaptic vesicles and its influences on spontaneous and evoked neurotransmission.

Neurons in the central nervous system communicate with each other by activating billions of tiny synaptic boutons distributed along their fine axons. These presynaptic varicosities are very crowded environments, comprising hundreds of synaptic vesicles. Only a fraction of these vesicles can be recruited in a single release episode, either spontaneous or evoked by action potentials. Since the seminal work by Fatt and Katz, spontaneous release has been modelled as a memoryless process. Nevertheless, at central synapses, experimental evidence indicates more complex features, including non-exponential distributions of release intervals and power-law behaviour in their rate. To describe these features, we developed a probabilistic model of spontaneous release based on Brownian motion of synaptic vesicles in the presynaptic environment. To account for different diffusion regimes, we based our simulations on fractional Brownian motion. We show that this model can predict both deviation from the Poisson hypothesis and power-law features in experimental quantal release series, thus suggesting that the vesicular motion by diffusion could per se explain the emergence of these properties. We demonstrate the efficacy of our modelling approach using electrophysiological recordings at single synaptic boutons and ultrastructural data. When this approach was used to simulate evoked responses, we found that the replenishment of the readily releasable pool driven by Brownian motion of vesicles can reproduce the characteristic binomial release distributions seen experimentally. We believe that our modelling approach supports the idea that vesicle diffusion and readily releasable pool dynamics are crucial factors for the physiological functioning of neuronal communication. KEY POINTS: We developed a new probabilistic model of spontaneous and evoked vesicle fusion based on simple biophysical assumptions, including the motion of vesicles before they dock to the release site. We provide closed-form equations for the interval distribution of spontaneous releases in the special case of Brownian diffusion of vesicles, showing that a power-law heavy tail is generated. Fractional Brownian motion (fBm) was exploited to simulate anomalous vesicle diffusion, including directed and non-directed motion, by varying the Hurst exponent. We show that our model predicts non-linear features observed in experimental spontaneous quantal release series as well as ultrastructural data of synaptic vesicles spatial distribution. Evoked exocytosis based on a diffusion-replenished readily releasable pool might explain the emergence of power-law behaviour in neuronal activity.

Proposal of a classification of cannulation damage in vascular access grafts based on clinical, ultrasound, and microscopic observations.

INTRODUCTION: Arteriovenous grafts (AVGs) serve as an alternative to native arteriovenous fistulas (AVFs) in the context of hemodialysis patient life planning. AVGs are more susceptible to developing outflow stenosis (due to intimal hyperplasia), thrombosis, and infections. However, an often overlooked contributor to AVG failure is cannulation damage. The objective of this paper is to assess the impact of cannulations on AVGs. We aim to establish a classification of AVG damage by comparing clinical data and ultrasound images with microscopic morphological findings obtained from explanted grafts. MATERIALS AND METHODS: This study is conducted at a single center. We included all patients who underwent AVG creation between 2011 and 2019. Comprehensive data on clinical history, follow-up, and complications were collected and reviewed. Duplex ultrasound (DUS) characteristics were documented, and all grafts explanted during the analysis period underwent optical microscopy evaluation. Finally, clinical data, along with DUS and microscopic findings, were integrated to derive a damage classification. RESULTS: During the study period, 247 patients underwent 334 early cannulation AVGs. The median follow-up duration was 714 days (IQR 392, 1195). One hundred eleven (33%) grafts were explanted. Clinical data and DUS findings were utilized to formulate a four-grade classification system indicating increasing damage. CONCLUSION: Cannulation damage alone does not solely account for AVG failure. It results from a biological host-mediated process that promotes the growth of intimal hyperplasia at the cannulation sites. This process is not clinically significant within the initial 2 years after AVG creation.

Erdheim-Chester disease: An in vivo human model of Mϕ activation at the crossroad between chronic inflammation and cancer.

Erdheim-Chester disease (ECD) is a rare histiocytosis characterized by infiltration of multiple tissues by CD68+ foamy Mϕs (or 'histiocytes'). Clinical manifestations arise from mass-forming lesions or from tissue and systemic inflammation. ECD histiocytes harbor oncogenic mutations along the MAPK-kinase signaling pathway (BRAFV600E in more than half of the patients), and secrete abundant pro-inflammatory cytokines and chemokines. Based on these features, ECD is considered an inflammatory myeloid neoplasm, and is accordingly managed with targeted kinase inhibitors or immunosuppressive and cytokine-blocking agents. Evidence is emerging that maladaptive metabolic changes, particularly up-regulated glycolysis, represent an additional, mutation-driven feature of ECD histiocytes, which sustains deregulated and protracted pro-inflammatory activation and cytokine production. Besides translational relevance to the management of ECD patients and to the development of new therapeutic approaches, recognition of ECD as a natural human model of chronic, maladaptive Mϕ activation instructs the understanding of Mϕ dysfunction in other chronic inflammatory conditions.

Complex Immune Contextures Characterise Malignant Peritoneal Mesothelioma: Loss of Adaptive Immunological Signature in the More Aggressive Histological Types.

Malignant peritoneal mesothelioma (MpM), arising in the setting of local inflammation, is a rare aggressive tumour with a poor prognosis and limited therapeutic options. The three major MpM histological variants, epithelioid (E-MpMs), biphasic, and sarcomatoid MpMs (S-MpMs), are characterised by an increased aggressiveness and enhanced levels of EZH2 expression. To investigate the MpM immune contexture along the spectrum of MpM histotypes, an extended in situ analysis was performed on a series of 14 cases. Tumour-infiltrating immune cells and their functionality were assessed by immunohistochemistry, immunofluorescence, qRT-PCR, and flow cytometry analysis. MpMs are featured by a complex immune landscape modulated along the spectrum of MpM variants. Tumour-infiltrating T cells and evidence for pre-existing antitumour immunity are mainly confined to E-MpMs. However, Th1-related immunological features are progressively impaired in the more aggressive forms of E-MpMs and completely lost in S-MpM. Concomitantly, E-MpMs show also signs of active immune suppression, such as the occurrence of Tregs and Bregs and the expression of the immune checkpoint inhibitory molecules PD1 and PDL1. This study enriches the rising rationale for immunotherapy in MpM and points to the E-MpMs as the most immune-sensitive MpM histotypes, but it also suggests that synergistic interventions aimed at modifying the tumour microenvironment (TME) should be considered to make immunotherapy beneficial for these patients.

A novel computational method for automatic segmentation, quantification and comparative analysis of immunohistochemically labeled tissue sections.

BACKGROUND: In the clinical practice, the objective quantification of histological results is essential not only to define objective and well-established protocols for diagnosis, treatment, and assessment, but also to ameliorate disease comprehension. SOFTWARE: The software MIAQuant_Learn presented in this work segments, quantifies and analyzes markers in histochemical and immunohistochemical images obtained by different biological procedures and imaging tools. MIAQuant_Learn employs supervised learning techniques to customize the marker segmentation process with respect to any marker color appearance. Our software expresses the location of the segmented markers with respect to regions of interest by mean-distance histograms, which are numerically compared by measuring their intersection. When contiguous tissue sections stained by different markers are available, MIAQuant_Learn aligns them and overlaps the segmented markers in a unique image enabling a visual comparative analysis of the spatial distribution of each marker (markers' relative location). Additionally, it computes novel measures of markers' co-existence in tissue volumes depending on their density. CONCLUSIONS: Applications of MIAQuant_Learn in clinical research studies have proven its effectiveness as a fast and efficient tool for the automatic extraction, quantification and analysis of histological sections. It is robust with respect to several deficits caused by image acquisition systems and produces objective and reproducible results. Thanks to its flexibility, MIAQuant_Learn represents an important tool to be exploited in basic research where needs are constantly changing.

Tumor-derived microRNAs induce myeloid suppressor cells and predict immunotherapy resistance in melanoma.

The accrual of myeloid-derived suppressor cells (MDSCs) represents a major obstacle to effective immunotherapy in cancer patients, but the mechanisms underlying this process in the human setting remain elusive. Here, we describe a set of microRNAs (miR-146a, miR-155, miR-125b, miR-100, let-7e, miR-125a, miR-146b, miR-99b) that are associated with MDSCs and resistance to treatment with immune checkpoint inhibitors in melanoma patients. The miRs were identified by transcriptional analyses as being responsible for the conversion of monocytes into MDSCs (CD14+HLA-DRneg cells) mediated by melanoma extracellular vesicles (EVs) and were shown to recreate MDSC features upon transfection. In melanoma patients, these miRs were increased in circulating CD14+ monocytes, plasma, and tumor samples, where they correlated with the myeloid cell infiltrate. In plasma, their baseline levels clustered with the clinical efficacy of CTLA-4 or programmed cell death protein 1 (PD-1) blockade. Hence, MDSC-related miRs represent an indicator of MDSC activity in cancer patients and a potential blood marker of a poor immunotherapy outcome.

pH regulators to target the tumor immune microenvironment in human hepatocellular carcinoma.

Interfering with tumor metabolism is an emerging strategy for treating cancers that are resistant to standard therapies. Featuring a rapid proliferation rate and exacerbated glycolysis, hepatocellular carcinoma (HCC) creates a highly hypoxic microenvironment with excessive production of lactic and carbonic acids. These metabolic conditions promote disease aggressiveness and cancer-related immunosuppression. The pH regulatory molecules work as a bridge between tumor cells and their surrounding milieu. Herein, we show that the pH regulatory molecules CAIX, CAXII and V-ATPase are overexpressed in the HCC microenvironment and that interfering with their pathways exerts antitumor activity. Importantly, the V-ATPase complex was expressed by M2-like tumor-associated macrophages. Blocking ex vivo V-ATPase activity established a less immune-suppressive tumor microenvironment and reversed the mesenchymal features of HCC. Thus, targeting the unique cross-talk between tumor cells and the tumor microenvironment played by pH regulatory molecules holds promise as a strategy to control HCC progression and to reduce the immunosuppressive pressure mediated by the hypoxic/acidic metabolism, particularly considering the potential combination of this strategy with emerging immune checkpoint-based immunotherapies.

Modeling multiple myeloma-bone marrow interactions and response to drugs in a 3D surrogate microenvironment.

Multiple myeloma develops primarily inside the bone marrow microenvironment, that confers pro-survival signals and drug resistance. 3D cultures that reproduce multiple myeloma-bone marrow interactions are needed to fully investigate multiple myeloma pathogenesis and response to drugs. To this purpose, we exploited the 3D Rotary Cell Culture System bioreactor technology for myeloma-bone marrow co-cultures in gelatin scaffolds. The model was validated with myeloma cell lines that, as assessed by histochemical and electron-microscopic analyses, engaged contacts with stromal cells and endothelial cells. Consistently, pro-survival signaling and also cell adhesion-mediated drug resistance were significantly higher in 3D than in 2D parallel co-cultures. The contribution of the VLA-4/VCAM1 pathway to resistance to bortezomib was modeled by the use of VCAM1 transfectants. Soluble factor-mediated drug resistance could be also demonstrated in both 2D and 3D co-cultures. The system was then successfully applied to co-cultures of primary myeloma cells-primary myeloma bone marrow stromal cells from patients and endothelial cells, allowing the development of functional myeloma-stroma interactions and MM cell long-term survival. Significantly, genomic analysis performed in a high-risk myeloma patient demonstrated that culture in bioreactor paralleled the expansion of the clone that ultimately dominated in vivo Finally, the impact of bortezomib on myeloma cells and on specialized functions of the microenvironment could be evaluated. Our findings indicate that 3D dynamic culture of reconstructed human multiple myeloma microenvironments in bioreactor may represent a useful platform for drug testing and for studying tumor-stroma molecular interactions.

MIAQuant, a novel system for automatic segmentation, measurement, and localization comparison of different biomarkers from serialized histological slices.

In the clinical practice, automatic image analysis methods quickly quantizing histological results by objective and replicable methods are getting more and more necessary and widespread. Despite several commercial software products are available for this task, they are very little flexible, and provided as black boxes without modifiable source code. To overcome the aforementioned problems, we employed the commonly used MATLAB platform to develop an automatic method, MIAQuant, for the analysis of histochemical and immunohistochemical images, stained with various methods and acquired by different tools. It automatically extracts and quantifies markers characterized by various colors and shapes; furthermore, it aligns contiguous tissue slices stained by different markers and overlaps them with differing colors for visual comparison of their localization. Application of MIAQuant for clinical research fields, such as oncology and cardiovascular disease studies, has proven its efficacy, robustness and flexibility with respect to various problems; we highlight that, the flexibility of MIAQuant makes it an important tool to be exploited for basic researches where needs are constantly changing. MIAQuant software and its user manual are freely available for clinical studies, pathological research, and diagnosis.

Adaptive Immunity in Fibrosarcomatous Dermatofibrosarcoma Protuberans and Response to Imatinib Treatment.

Dermatofibrosarcoma protuberans (DFSP), although rare, is the most frequent skin sarcoma. Here, we focus on DFSP carrying the fibrosarcomatous transformation (FS-DFSP). FS-DFSP responds to imatinib (IM); however, tumor relapse often occurs. In a series of 21 pre- and post-treatment FS-DFSP samples, the present study explored the events that occur at the tumor site during IM therapy. Gene expression profile and immunohistochemistry analyses documented the occurrence of IM-induced senescence phenotype in the tumor cells and showed the accumulation of activated CD3+ T cells and CD163+CD14+ myeloid cells expressing the CD209 marker in post-therapy lesions. In post-IM specimens, the pathological response and tumor apoptosis were tightly associated with T-cell infiltration, thus suggesting the presence of an ongoing anti-tumor response, which was further confirmed by in vitro functional assays with CD3+ T cells isolated from an IM-responding FS-DFSP lesion. The integration of targeted therapies with immune therapies is currently under investigation to achieve longer tumor control. Our data outline the in situ immunological effects of IM and classify IM-treated FS-DFSP as potentially sensitive to immunotherapy, thus providing the rationale for further investigations of combination treatment for this soft-tissue sarcoma.

Plasma Chromogranin A as a marker of cardiovascular involvement in Erdheim-Chester disease.

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis (LCH) characterized by tissue infiltration with CD68(+) foamy histiocytes. TNF-related chronic inflammation and mutations in the MAP kinase signaling pathway in histiocytes are recognized as the two major pathogenic events. Among pleomorphic clinical manifestations, cardiovascular involvement is frequent and prognostically relevant. Evaluation of ECD clinical course and response to treatment is, however, still challenging. Taking advantage of the two largest cohorts of ECD patients worldwide, we investigated the relevance and the potential of circulating Chromogranin A (CgA), a pro-hormone involved in cardiovascular homeostasis and inflammation, as a biomarker of response to therapy in ECD. Consistent with other TNF-related inflammatory diseases, we found that not only TNF-α and soluble TNF-Receptors (sTNF-Rs), but also CgA plasma levels were significantly increased in ECD patients compared to controls. CgA, but not sTNF-Rs, discriminated cardiovascular involvement in ECD patients and correlated with pro-Brain Natriuretic Peptide (pro-BNP). In a single case, where a cardiac biopsy was available, CgA was found expressed by cardiomyocytes but not by infiltrating histiocytes. In four ECD patients, where serial determination of these parameters was obtained, the kinetics of sTNF-Rs and CgA paralleled response to therapy with anti-cytokine inhibitors; specifically, sTNF-Rs overlapped TNF-associated inflammation, while CgA, together with pro-BNP, closely mirrored response of cardiac disease. Our data indicate that both sTNF-Rs and CgA are linked to ECD pathophysiology. Moreover, CgA, in concert with pro-BNP, can be further exploited to fulfill the unmet clinical need of non-invasive reliable biomarkers of cardiac disease in these patients.

CRLF2 over-expression is a poor prognostic marker in children with high risk T-cell acute lymphoblastic leukemia.

Pediatric T-ALL patients have a worse outcome compared to BCP-ALL patients and they could benefit from new prognostic marker identification. Alteration of CRLF2 gene, a hallmark correlated with poor outcome in BCP-ALL, has not been reported in T-ALL.We analyzed CRLF2 expression in 212 T-ALL pediatric patients enrolled in AIEOP-BFM ALL2000 study in Italian and German centers.Seventeen out of 120 (14.2%) Italian patients presented CRLF2 mRNA expression 5 times higher than the median (CRLF2-high); they had a significantly inferior event-free survival (41.2%±11.9 vs. 68.9%±4.6, p=0.006) and overall survival (47.1%±12.1 vs. 73.8%±4.3, p=0.009) and an increased cumulative incidence of relapse/resistance (52.9%±12.1 vs. 26.2%±4.3, p=0.007) compared to CRLF2-low patients. The prognostic value of CRLF2 over-expression was validated in the German cohort. Of note, CRLF2 over-expression was associated with poor prognosis in the high risk (HR) subgroup where CRLF2-high patients were more frequently allocated.Interestingly, although in T-ALL CRLF2 protein was localized mainly in the cytoplasm, in CRLF2-high blasts we found a trend towards a stronger TSLP-induced pSTAT5 response, sensitive to the JAK inhibitor Ruxolitinib.In conclusion, CRLF2 over-expression is a poor prognostic marker identifying a subset of HR T-ALL patients that could benefit from alternative therapy, potentially targeting the CRLF2 pathway.

Immunomodulatory Factors Control the Fate of Melanoma Tumor Initiating Cells.

Melanoma is a highly heterogeneous tumor for which recent evidence supports a model of dynamic stemness. Melanoma cells might temporally acquire tumor-initiating properties or switch from a status of tumor-initiating cells (TICs) to a more differentiated one depending on the tumor context. However, factors driving these functional changes are still unknown. We focused on the role of cyto/chemokines in shaping TICs isolated directly from tumor specimens of two melanoma patients, namely Me14346S and Me15888S. We analyzed the secretion profile of TICs and of their corresponding melanoma differentiated cells and we tested the ability of cyto/chemokines to influence TIC self-renewal and differentiation. We found that TICs, grown in vitro as melanospheres, had a complex secretory profile as compared to their differentiated counterparts. Some factors, such as CCL-2 and IL-8, also produced by adherent melanoma cells and melanocytes did not influence TIC properties. Conversely, IL-6, released by differentiated cells, reduced TIC self-renewal and induced TIC differentiation while IL-10, produced by Me15888S, strongly promoted TIC self-renewal through paracrine/autocrine actions. Complete neutralization of IL-10 activity by gene silencing and antibody-mediated blocking of the IL-10Rα was required to sensitize Me15888S to IL-6-induced differentiation. For the first time these results show that functional heterogeneity of melanoma could be directly influenced by inflammatory and suppressive soluble factors, with IL-6 favoring TIC differentiation, and IL-10 supporting TIC self-renewal. Thus, understanding the tumor microenvironment (TME) role in modulating melanoma TIC phenotype is fundamental to identifying novel therapeutic targets to achieve long-lasting regression of metastatic melanoma. Stem Cells 2016;34:2449-2460.

TNF-Related Apoptosis-Inducing Ligand (TRAIL)-Armed Exosomes Deliver Proapoptotic Signals to Tumor Site.

PURPOSE: Exosomes deliver signals to target cells and could thus be exploited as an innovative therapeutic tool. We investigated the ability of membrane TRAIL-armed exosomes to deliver proapoptotic signals to cancer cells and mediate growth inhibition in different tumor models. EXPERIMENTAL METHODS AND RESULTS: K562 cells, transduced with lentiviral human membrane TRAIL, were used for the production of TRAIL(+) exosomes, which were studied by nanoparticle tracking analysis, cytofluorimetry, immunoelectronmicroscopy, Western blot, and ELISA. In vitro, TRAIL(+) exosomes induced more pronounced apoptosis (detected by Annexin V/propidium iodide and activated caspase-3) in TRAIL-death receptor (DR)5(+) cells (SUDHL4 lymphoma and INT12 melanoma), with respect to the DR5(-)DR4(+)KMS11 multiple myeloma. Intratumor injection of TRAIL(+) exosomes, but not mock exosomes, induced growth inhibition of SUDHL4 (68%) and INT12 (51%), and necrosis in KMS11 tumors. After rapid blood clearance, systemically administered TRAIL(+) exosomes accumulated in the liver, lungs, and spleen and homed to the tumor site, leading to a significant reduction of tumor growth (58%) in SUDHL4-bearing mice. The treatment of INT12-bearing animals promoted tumor necrosis and a not statistically significant tumor volume reduction. In KMS11-bearing mice, despite massive perivascular necrosis, no significant tumor growth inhibition was detected. CONCLUSIONS: TRAIL-armed exosomes can induce apoptosis in cancer cells and control tumor progression in vivo Therapeutic efficacy was particularly evident in intratumor setting, while depended on tumor model upon systemic administration. Thanks to their ability to deliver multiple signals, exosomes thus represent a promising therapeutic tool in cancer. Clin Cancer Res; 22(14); 3499-512. ©2016 AACR.

Characterization of fast-twitch and slow-twitch skeletal muscles of calsequestrin 2 (CASQ2)-knock out mice: unexpected adaptive changes of fast-twitch muscles only.

This study investigates the functional role of calsequestrin 2 (CASQ2) in both fast-twitch and slow-twitch skeletal muscles by using CASQ2-/- mice; CASQ2 is expressed throughout life in slow-twitch muscles, but only in the developmental and neonatal stages in fast-twitch muscles. CASQ2-/- causes increase in calsequestrin 1 (CASQ1) expression, but without functional changes in both muscle types. CASQ2-/- mice have ultrastructural changes in fast-twitch muscles only, i.e., formation of pentads and stacks in the sarcoplasmic reticulum.

Overcoming melanoma resistance to vemurafenib by targeting CCL2-induced miR-34a, miR-100 and miR-125b.

In melanoma, the adaptative cell response to BRAF inhibitors includes altered patterns of cytokine production contributing to tumor progression and drug resistance. Among the factors produced by PLX4032-resistant melanoma cell lines, CCL2 was higher compared to the sensitive parental cell lines and increased upon drug treatment. CCL2 acted as an autocrine growth factor for melanoma cells, stimulating the proliferation and resistance to apoptosis. In patients, CCL2 is detected in melanoma cells in tumors and in plasma at levels that correlate with tumor burden and lactate dehydrogenase. Vemurafenib treatment increased the CCL2 levels in plasma, whereas the long-term clinical response was associated with low CCL2 levels.Increased CCL2 production was associated with miRNA deregulation in the resistant cells. miR-34a, miR-100 and miR-125b showed high expression in both resistant cells and in tumor biopsies that were obtained from treated patients, and they were involved in the control of cell proliferation and apoptosis. Inhibition of CCL2 and of the selected miRNAs restored both the cell apoptosis and the drug efficacy in resistant melanoma cells. Therefore, CCL2 and miRNAs are potential prognostic factors and attractive targets for counteracting treatment resistance in metastatic melanoma.

Naproxcinod shows significant advantages over naproxen in the mdx model of Duchenne Muscular Dystrophy.

BACKGROUND: In dystrophin-deficient muscles of Duchenne Muscular Dystrophy (DMD) patients and the mdx mouse model, nitric oxide (NO) signalling is impaired. Previous studies have shown that NO-donating drugs are beneficial in dystrophic mouse models. Recently, a long-term treatment (9 months) of mdx mice with naproxcinod, an NO-donating naproxen, has shown a significant improvement of the dystrophic phenotype with beneficial effects present throughout the disease progression. It remains however to be clearly dissected out which specific effects are due to the NO component compared with the anti-inflammatory activity associated with naproxen. Understanding the contribution of NO vs the anti-inflammatory effect is important, in view of the potential therapeutic perspective, and this is the final aim of this study. METHODS: Five-week-old mdx mice received either naproxcinod (30 mg/kg) or the equimolar dose of naproxen (20 mg/kg) in the diet for 6 months. Control mdx mice were used as reference. Treatments (or vehicle for control groups) were administered daily in the diet. For the first 3 months the study was performed in sedentary animals, then all mice were subjected to exercise until the sixth month. Skeletal muscle force was assessed by measuring whole body tension in sedentary animals as well as in exercised mice and resistance to fatigue was measured after 3 months of running exercise. At the end of 6 months of treatment, animals were sacrificed for histological analysis and measurement of naproxen levels in blood and skeletal muscle. RESULTS: Naproxcinod significantly ameliorated skeletal muscle force and resistance to fatigue in sedentary as well as in exercised mice, reduced inflammatory infiltrates and fibrosis deposition in both cardiac and diaphragm muscles. Conversely, the equimolar dose of naproxen showed no effects on fibrosis and improved muscle function only in sedentary mice, while the beneficial effects in exercised mice were lost demonstrating a limited and short-term effect. CONCLUSION: In conclusion, this study shows that NO donation may have an important role, in addition to anti-inflammatory activity, in slowing down the progression of the disease in the mdx mouse model therefore positioning naproxcinod as a promising candidate for treatment of DMD.

Melan-A/MART-1 immunity in a EWS-ATF1 translocated clear cell sarcoma patient treated with sunitinib: a case report.

BACKGROUND: Clear cell sarcoma (CCS), initially named malignant melanoma of soft parts, is an aggressive soft tissue sarcoma (STS) that, due to MITF activation, shares with melanoma the expression of melanocyte differentiation antigens. CCS is poorly sensitive to chemotherapy. Multi-kinase inhibitors have been used as therapeutic agents. In the case we report here, treatment with sunitinib induced a long-lasting clinical response that was associated with an immune activation directed against Melan-A/MART-1 antigen. CASE PRESENTATION: A 28 years old female patient with an advanced molecularly confirmed CCS resistant to conventional chemotherapy was started in January 2012 on sunitinib, 37.5 mg/day, with evidence of radiologic and metabolic response at the primary and metastatic sites of disease. Pathologic response and loss of the Melan-A/MART-1 antigen were evidenced on residual tumor removed in April 2012. Immunological monitoring performed on patient's blood during pharmacological treatment revealed a systemic, Melan-A/MART-1 specific immunity and a low frequency of immunosuppressive cells. Sunitinib was restarted in May 2012, with a new response, and continued for 11 months although with repeatedly interruptions due to toxicity. Disease progression and new responses were documented at each treatment interruption and restart. Sunitinib was definitively interrupted in April 2013 for disease progression. CONCLUSION: The analysis of this case proves that antigens expressed by CCS, as for melanoma, can be immunogenic in vivo and that tumor-antigen specific T cells may exert anti-tumor activity in CCS patient. Thus, manipulation of the immune response may have therapeutic potential for this STS subtype and immunotherapy approaches, can be promising therapeutic options for these patients.