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Background Cancer is the second leading cause of death globally. Early detection and disease management lead to a better survival rate. Consequently, discovery of novel methods in cancer early diagnosis is a field of active research. Minimally invasive liquid biopsies are generating growing interest. Circulating tumour cells (CTCs) have been identified in patients’ blood; nevertheless, these cells are rare and heterogeneous. Exosomes are extracellular nanovesicles released into the extracellular environment via the endosomal vesicle pathway and found in different body fluids. Exosomes deliver bioactive cargo such as proteins, mRNA and miRNA to recipient cells in the tumour environment. We have recently shown that heat shock protein 70 (HSP70) is detected in the membrane of tumour-derived exosomes, in contrast to normal cells. One single cancer cell can release thousands of HSP70-exosomes, facilitating detection. The aim of the pilot study ExoDiag is to determine whether it is possible to detect and quantify HSP70-exosomes in blood in patients with solid cancers. Methods Bicentric pilot study that will include 60 adult patients with metastatic and non-metastatic solid tumours and 20 healthy volunteers. Exosomes will be isolated from blood and urine samples, and HSP70 concentration will be determined. Patients will be followed for 1 year. The study is sponsored by Georges-François Leclerc Centre and is currently ongoing. Discussion We expect to demonstrate that HSP70-exosomes could be a powerful tool to diagnose cancer and to guide clinicians in therapeutic decision-making, improving patient’s care. Trial Registration ClinicalTrials.gov identifier NCT02662621. Registered 20 January 2016, https://clinicaltrials.gov/ct2/show/study/NCT02662621?term=NCT02662621&rank=1

We aimed to study the expression of circulating heat-shock protein HSP70 and exosomes in plasma of a cohort of patients with Alzheimer's disease (AD) and frontotemporal dementia (FTD) at different stages. We performed correlations with clinical scales and FDG-PET. HSP70 levels were higher within exosomes than free in plasma. Moderate correlations were found between exosomal HSP70 and CDR, FTLD-CDR, and extension of hypometabolism. Our results suggest modifications in the level of exosomal HSP70 during the course of neurodegeneration, regardless of AD or FTD, and therefore HSP70 could have a potential role in the follow-up of these disorders.

Exosomes are involved in modulating the immune system and mediating communication between cells. The aim of this study was to investigate the involvement of exosomes in psoriasis. Exosomes from patients with psoriasis were analysed by nanoparticle tracking analysis and protein expression was analysed by western blotting. The concentration of HSP70 was determined by an enzyme-linked immunosorbent assay, and concentrations of interleukin (IL)-1β, IL-2, IL-6, IL-10, IL-17A and tumour necrosis factor alpha (TNF-α) were determined by flow cytometry. Based on the severity of psoriasis, evaluated by body surface area (≤ 10% vs. > 10%), 2 groups of patients were compared (49 with mild psoriasis and 71 with moderate-to-severe psoriasis). The number (2.52×1011 ± 2.29×1010 vs. 1.79×1011 ± 1.93×1010, p = 0.19) and size (94.44 ± 22.00 nm vs. 96.87 ± 28.30 nm, p = 0.72) of exosomes and the concentration of HSP70 in the exosomes were not significantly different in the 2 groups of patients. IL-17A exosome levels were significantly higher in patients with moderate-to-severe psoriasis compared with those with mild psoriasis (p = 0.02). There were no significant differences in levels of TNF-α, IL-1, IL-2, IL-6 and IL-10. This study shows, for the first time, the presence of circulating exosomes in patients with psoriasis. These data confirm the involvement of circulating exosomes in psoriasis, in particular in moderate-to-severe psoriasis, through IL-17A-producing exosomes.

In the era of immunotherapies there is an urgent need to implement the use of circulating biomarkers in clinical practice to facilitate personalized therapy and to predict treatment response. We conducted a prospective study to evaluate the usefulness of circulating exosomal-PD-L1 in melanoma patients’ follow-up. We studied the dynamics of exosomal-PD-L1 from 100 melanoma patients by using an enzyme-linked immunosorbent assay. We found that PD-L1 was secreted through exosomes by melanoma cells. Exosomes carrying PD-L1 had immunosuppressive properties since they were as efficient as the cancer cell from which they derive at inhibiting T-cell activation. In plasma from melanoma patients, the level of PD-L1 (n= 30, median 64.26 pg/mL) was significantly higher in exosomes compared to soluble PD-L1 (n= 30, 0.1 pg/mL). Furthermore, exosomal-PD-L1 was detected in all patients whereas only 67% of tumour biopsies were PD-L1 positive. Although baseline exosomal-PD-L1 levels were not associated with clinic-pathologic characteristics, their variations after the cures (ΔExoPD-L1) correlated with the tumour response to treatment. A ΔExoPD-L1 cut-off of> 100 was defined, yielding an 83% sensitivity, a 70% specificity, a 91% positive predictive value and 54% negative predictive values for disease progression. The use of the cut-off allowed stratification in two groups of patients statistically different concerning overall survival and progression-free survival. PD-L1 levels in circulating exosomes seem to be a more reliable marker than PD-L1 expression in tumour biopsies. Monitoring of circulating exosomal-PD-L1 may be useful to predict the tumour response to treatment and clinical outcome.

Colorectal cancer (CRC) is one of the major causes of cancer-related deaths worldwide. Tumor microenvironment (TME) contains many cell types including stromal cells, immune cells, and endothelial cells. The TME modulation explains the heterogeneity of response to therapy observed in patients. In this context, exosomes are emerging as major contributors in cancer biology. Indeed, exosomes are implicated in tumor proliferation, angiogenesis, invasion, and premetastatic niche formation. They contain bioactive molecules such as proteins, lipids, and RNAs. More recently, many studies on exosomes have focused on miRNAs, small noncoding RNA molecules able to influence protein expression. In this review, we describe miRNAs transported by exosomes in the context of CRC and discuss their influence on TME and their potential as circulating biomarkers. This overview underlines emerging roles for exosomal miRNAs in cancer research for the near future.

Heat shock protein 27 (HSP27/HSPB1) is a stress-inducible chaperone that facilitates cancer development by its proliferative and anti-apoptotic functions. The OGX-427 antisense oligonucleotide against HSP27 has been reported to be beneficial against idiopathic pulmonary fibrosis. Here we show that OGX-427 is effective in two murine models of thrombopoietin- and JAKV617F-induced myelofibrosis. OGX-427 limits disease progression and is associated with a reduction in spleen weight, in megakaryocyte expansion and, for the JAKV617F model, in fibrosis. HSP27 regulates the proliferation of JAK2V617F-positive cells and interacts directly with JAK2/STAT5. We also show that its expression is increased in both CD34+ circulating progenitors and in the serum of patients with JAK2-dependent myeloproliferative neoplasms with fibrosis. Our data suggest that HSP27 plays a key role in the pathophysiology of myelofibrosis and represents a new potential therapeutic target for patients with myeloproliferative neoplasms., Myelofibrosis is a chronic degenerative disorder characterized by progressive bone marrow fibrosis. Here, the authors show that the chaperone HSP27 contributes to myelofibrosis via regulation of the JAK2/STAT5 pathway, and that antisense oligonucleotides targeting HSP27 are effective in two mouse models of the disease

9517 Background: In the era of effective molecular targeted treatments and immunotherapies, there is an urgent need to implement the use of circulating biomarkers in the clinic to facilitate personalized therapy and predict treatment response. We conducted a retrospective study to demonstrate the involvement of circulating PD-L1 exosomes in melanoma patients. Methods: One hundred melanoma patients were included. Exosomes were isolated by ultracentrifugation and evaluated by nanoparticle tracking analysis using a NS300 Instrument (Nanosight, Amesbury, UK). Isolated exosomes were tested for the expression of exosomes markers such as TSG101. PD-L1 expression in plasma and in melanoma plasma-derived exosomes (ExoPD-L1) was measured using an enzyme-linked immunosorbent assay (PD-L1 Human ELISA Kit, Invitrogen). Results: First, ExoPD-L1 was assessed in melanoma cell lines. Exosomes may have a role in cancer immunosuppression mediated by T-cells since they were as efficient as cancer cells to inhibit T-cells activation. In melanoma patients, ExoPD-L1 (median 64,26 pg/mL) was significantly higher than free PD-L1 in the plasma which was barely detectable (0,1 pg/mL). Furthermore, ExoPD-L1 was detected in all patients whereas only 67 % were PD-L1 positive in tumor. Although baseline ExoPD-L1 levels were not associated with clinicopathologic characteristics and tumour burden, ExoPD-L1 variations (ΔExoPD-L1) after treatment correlated with tumor response and survival. A ΔExoPD-L1 cut-off of > 100 was defined, yielding a 83% sensitivity, a 70% specificity, a 91% positive predictive value and a 54% negative predictive values for disease progression. The use of this cut-off allowed stratification in two groups of patients statistically different in terms of overall survival and progression free survival. Conclusions: PD-L1 level in circulating exosomes may be a more reliable marker than PD-L1 expression in the tumor tissue. Monitoring of circulating exosomal PD-L1 may be a promising biomarker to predict tumor response and correlate with survival.

IF 2.06; International audience