Diagnostic performance of circulating exosomes in human cancer: A meta-analysis

Selective Internal Radiotherapy Alters the Profiles of Systemic Extracellular Vesicles in Hepatocellular Carcinoma

Incidence of hepatocellular carcinoma (HCC) is increasing globally. Radioembolization (RE)/selective internal radiotherapy (SIRT) is a promising treatment for inoperable HCC. RE triggers an immune response, involving extracellular vesicles (EVs) which are crucial for cell communication and tumor development. This study explores EV immune profiles and origins in patients with inoperable HCC before and after SIRT/RE. Blood samples from 50 HCC-patients treated with SIRT/RE were collected before and after therapy to determine cytokines and isolate EVs using size exclusion chromatography. The dynamic range and EV quality required for detecting variations in surface markers were assessed. Thirty-seven EV surface markers were analyzed using flow cytometry and correlated with clinical parameters. Several immunological markers (CD4, CD2, CD40, CD45, CD49e, CD69, CD209-EVs) were present in the circulation of HCC patients. These markers positively correlated with therapy response and survival. Conversely, B cell CD20, endothelial cell CD146, platelet CD49e, and CD41b EV markers negatively correlated with 60-day survival. Elevated levels of IL-6 and IL-8 before therapy correlated negatively with patient survival, coinciding with a positive correlation with CD20-positive EVs. Plasma EVs from HCC patients exhibit immunological, cancer, and coagulation markers, including potential biomarkers (CD4, CD20, CD49e, CD146). These may enhance our understanding of cancer biology and facilitate SIRT therapy monitoring.

Small Extracellular Vesicles and Their Involvement in Cancer Resistance: An Up-to-Date Review

In recent years, tremendous progress has been made in understanding the roles of extracellular vesicles (EVs) in cancer. Thanks to advancements in molecular biology, it has been found that the fraction of EVs called exosomes or small EVs (sEVs) modulates the sensitivity of cancer cells to chemotherapeutic agents by delivering molecularly active non-coding RNAs (ncRNAs). An in-depth analysis shows that two main molecular mechanisms are involved in exosomal modified chemoresistance: (1) translational repression of anti-oncogenes by exosomal microRNAs (miRs) and (2) lack of translational repression of oncogenes by sponging of miRs through long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs). At the cellular level, these processes increase the proliferation and survival of cancer cells and improve their ability to metastasize and resist apoptosis. In addition, studies in animal models have shown enhancing tumor size under the influence of exosomal ncRNAs. Ultimately, exosomal ncRNAs are responsible for clinically significant chemotherapy failures in patients with different types of cancer. Preliminary data have also revealed that exosomal ncRNAs can overcome chemotherapeutic agent resistance, but the results are thoroughly fragmented. This review presents how exosomes modulate the response of cancer cells to chemotherapeutic agents. Understanding how exosomes interfere with chemoresistance may become a milestone in developing new therapeutic options, but more data are still required.

Extracellular Vesicles and Circulating Tumour Cells - complementary liquid biopsies or standalone concepts?

Liquid biopsies do promise a lot, but are they keeping it? In the past decade, additional novel biomarkers qualified to be called like that, of which, some took necessary hurdles resulting in FDA approval and clinical use. Some others are since a while around, well known and were once regarded to be a game changer in cancer diagnosis or cancer screening. But, during their clinical use limitations were observed from statistical significance and questions raised regarding their robustness, that eventually led to be dropped from associated clinical guidelines for certain applications including cancer diagnosis. The purpose of this review isn't to give a broad overview of all current liquid biopsy as biomarkers, weight them and promise a brighter future in cancer prevention, but rather to take a deeper look on two of those who do qualify to be called liquid biopsies now or then. These two are probably of greatest interest conceptually and methodically, and likely have the highest chances to be in clinical use soon, with a portfolio extension over their original conceptual usage. We aim to dig deeper beyond cancer diagnosis or cancer screening. Actually, we aim to review in depth extracellular vesicles (EVs) and compare with circulating tumour cells (CTCs). The latter methodology is partially FDA approved and in clinical use. We will lay out similarities as taking advantage of surface antigens on EVs and CTCs in case of characterization and quantification. But drawing readers' attention to downstream application based on capture/isolation methodology and simply on their overall nature, here apparently being living material eventually recoverable as CTCs are vs. dead material with transient effects on recipient cell as in case of EVs. All this we try to bring in perspective, compare and conclude towards which future direction we are aiming for, or should aim for. Do we announce a winner between CTCs vs EVs? No, but we provide good reasons to intensify research on them.

Diagnostic value of exosomes in patients with liver cancer: a systematic review

BACKGROUND

Liver cancer is a disease with high morbidity and mortality. More and more studies have shown that exosomes can be used as biomarkers for the diagnosis of liver cancer, but their diagnostic accuracy is still unclear. Therefore, this meta-analysis summarizes various studies on the diagnostic value of exosomes for liver cancer.

METHODS

A comprehensive search was carried out based on the set search terms in PubMed, Web of Science and Wiley until April 1, 2022. All statistical analyses were performed by STATA 17 statistical software and Review Manager 5.4. Quality Assessment for Studies of Diagnostic Accuracy 2 tool was applied to evaluate the quality of included articles. Random effects model was used to calculate various diagnostic indicators.

RESULTS

A total of 47 studies were included in this meta-analysis. The number of participants was 3196. The combined sensitivity, specificity and the area under the curve with 95% confidence intervals (95% CI) were, respectively 0.80 (0.75-0.84), 0.83 (0.79-0.87), 0.89 (0.85-0.91).

CONCLUSIONS

This meta-analysis shows that exosomes have good diagnostic accuracy for liver cancer and can be used as an effective biomarker for the diagnosis of liver cancer.

Selective Internal Radiotherapy Changes the Immune Profiles of Extracellular Vesicles and Their Immune Origin in Patients with Inoperable Cholangiocarcinoma

The incidence of cholangiocellular carcinoma (CCA) is rising worldwide. As there are no specific early symptoms or specific markers of CCA, it is often diagnosed in later inoperable stages. Accumulating evidence underlines the importance of radiation therapy in the induction of antitumor immunity. The surface protein composition on extracellular vesicles (EVs) relates to originating cells and thus may play a role in vesicle function. We assessed immune profiles of EVs and their immune origin in patients with inoperable CCA prior and after selective internal radiotherapy (SIRT). A total of 47 CCA patients receiving SIRT and 12 healthy volunteers (HV) were included. Blood was withdrawn before therapy (pre T) and after T. EVs were purified from plasma by cluster of differentiation (CD)9-, CD63-, and CD81-immunobead isolation. To detect differently abundant surface markers, dynamic range and EVs input quality were assessed. A total of 37 EVs surface markers were measured by flow cytometry and correlated either with the administered activity dose (MBq) or with the interval until death (month). EVs phenotyping identified lymphocytes, B cells, NK cells, platelets, endothelial cells, leukocyte activation, B cell activation, T and B cell adhesion markers, stem/progenitor cells, and antigen-presenting cells (APC) as EVs-parenteral cells. CD4 and CD8 significantly declined, while other markers significantly increased in CCA patients pre T vs. HV. Platelets-deriving EVs significantly decreased, normalizing to levels of HV but still significantly increasing vs. HV post SIRT. B cells-deriving EVs significantly increased pre T vs. HV, positively correlating with administered activity dose. MHCII and CD40 EVs significantly increased pre SIRT and negatively correlated with administered activity dose, while EVs from antigen presenting cells and CD49e pre SIRT positively correlated with survival time after therapy. Increased levels of CD24 and CD44 in cancer pre T were significantly decreased post T. Among the heterogeneity of EVs that was demonstrated, in particular, B cells-deriving, MHCII, and CD40 positive or APC-deriving EVs need to be further studied for their diagnostic or prognostic relevance in clinical scenarios.

The diagnostic value of exosomal circular RNAs in cancer patients: A systematic review and meta-analysis

BACKGROUND

Recently, serum exosomal circular RNAs (circRNAs) were applied to discriminate cancer patients from healthy individuals, indicating that exosomal circRNAs have the potential to be novel biomarkers for cancer diagnosis. This study aims to summarize the role of exosomal circRNAs in cancer diagnosis by a meta-analysis.

METHODS

A comprehensive literature search was conducted up to July 2021 in PubMed, Web of Science, EMBASE, and Cochrane Database. To evaluate the diagnostic value, the sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the curve (AUC) were pooled. Threshold effect followed by subgroup analysis and meta-regression were performed to explore the source of heterogeneity. Sensitivity analysis was performed to assess the stability of this meta-analysis model. Fagan plots and likelihood ratio scattergrams were used to explore the potential clinical significance.

RESULTS

Ten eligible studies with 514 controls and 557 patients were included in this diagnostic meta-analysis. The pooled sensitivity, specificity, PLR, NLR, and DOR were 0.75 (95% CI: 0.65-0.83), 0.84 (95% CI, 0.78-0.89), 5.87 (95% CI, 3.67-9.38), 0.28 (95% CI, 0.19-0.40), and 21.15 (95% CI, 10.25-43.68), respectively. The AUC was 0.89 (95% CI, 0.86-0.91). Sensitivity analysis showed that four studies had an impact on the pooled results and mainly contributed to the heterogeneity. Fagan's nomogram revealed that the prior probability of 20%, the post probability positive, the post probability negative were 59% and 6%, respectively.

CONCLUSION

Our results suggested that exosomal circRNAs might serve as powerful biomarkers in detecting cancers with high sensitivity and specificity. However, more well-designed and multicenter diagnostic tests are needed to validate our results.

Human Plasma Extracellular Vesicle Isolation and Proteomic Characterization for the Optimization of Liquid Biopsy in Multiple Myeloma

Cancer cells secrete membranous extracellular vesicles (EVs) which contain specific oncogenic molecular cargo (including oncoproteins, oncopeptides, and RNA) into their microenvironment and the circulation. As such, EVs including exosomes (small EVs) and microvesicles (large EVs) represent important circulating biomarkers for various diseases, including cancer and its progression. These circulating biomarkers offer a potentially minimally invasive and repeatable targets for analysis (liquid biopsy) that could aid in the diagnosis, risk stratification, and monitoring of cancer. Although their potential as cancer biomarkers has been promising, the identification and quantification of EVs in clinical samples remain challenging. Like EVs, other types of circulating biomarkers (including cell-free nucleic acids, cf-NAs; or circulating tumor cells, CTCs) may represent a complementary or alternative approach to cancer diagnosis. In the context of multiple myeloma (MM), a systemic cancer type that causes cancer cells to accumulate in the bone marrow, the specific role for EVs as biomarkers for diagnosis and monitoring remains undefined. Tumor heterogeneity along with the various subtypes of MM (such as non-secretory MM) that cannot be monitored using conventional testing (e.g. sequential serological testing and bone marrow biopsies) render liquid biopsy and circulating tumor-derived EVs a promising approach. In this protocol, we describe the isolation and purification of EVs from peripheral blood plasma (PBPL) collected from healthy donors and patients with MM for a biomarker discovery strategy. Our results demonstrate detection of circulating EVs from as little as 1 mL of MM patients' PBPL. High-resolution mass spectrometry (MS)-based proteomics promises to provide new avenues in identifying novel markers for detection, monitoring, and therapeutic intervention of disease. We describe biophysical characterization and quantitative proteomic profiling of disease-specific circulating EVs which may provide important implications for the development of cancer diagnostics in MM.

Human myeloma cell- and plasma-derived extracellular vesicles contribute to functional regulation of stromal cells

Circulating small extracellular vesicles (sEV) represent promising non-invasive biomarkers that may aid in the diagnosis and risk-stratification of multiple myeloma (MM), an incurable blood cancer. Here, we comprehensively isolated and characterized sEV from human MM cell lines (HMCL) and patient-derived plasma (psEV) by specific EV-marker enrichment and morphology. Importantly, we demonstrate that HMCL-sEV are readily internalised by stromal cells to functionally modulate proliferation. psEV were isolated using various commercial approaches and pre-analytical conditions (collection tube types, storage conditions) assessed for sEV yield and marker enrichment. Functionally, MM-psEV was shown to regulate stromal cell proliferation and migration. In turn, pre-educated stromal cells favour HMCL adhesion. psEV isolated from patients with both pre-malignant plasma cell disorders (monoclonal gammopathy of undetermined significance [MGUS]; smouldering MM [SMM]) and MM have a similar ability to promote cell migration and adhesion, suggesting a role for both malignant and pre-malignant sEV in disease progression. Proteomic profiling of MM-psEV (305 proteins) revealed enrichment of oncogenic factors implicated in cell migration and adhesion, in comparison to non-disease psEV. This study describes a protocol to generate morphologically-intact and biologically functional sEV capable of mediating the regulation of stromal cells, and a model for the characterization of tumour-stromal cross-talk by sEV in MM.

Diagnostic performance of circulating exosomes in human cancer: A meta-analysis

BACKGROUND

Cancer has become a public health problem with high morbidity and mortality. Recent publications have shown that exosomes can be used as potential diagnostic biomarkers of cancer. However, the diagnostic accuracy and reliability of circulating exosomes remain unclear. The present meta-analysis was conducted to comprehensively summarize the overall diagnostic performance of circulating exosomes for cancer.

METHODS

Eligible studies published up to June 27, 2019, on PubMed, Embase, and Cochrane Library were selected for the meta-analysis. All statistical analyses were performed by STATA 15.1 statistical software and Meta-DiSc 1.4. Quality Assessment for Studies of Diagnostic Accuracy 2 tool was used to access the quality of included studies. A bivariate mixed-effects model was applied to calculate the diagnostic indexes from included studies.

RESULTS

A total of 5924 participants comprising 3161 cases and 2763 controls from 42 eligible studies were analyzed. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio, and the area under the curve with 95% confidence intervals (95% CI) were as follows: 0.79 (0.75-0.82), 0.81 (0.78-0.84), 4.1 (3.5-4.8), 0.26 (0.22-0.31), 16 (12-21), and 0.87 (0.84-0.89), respectively. Sensitivity analysis suggested no study exclusively contributed to the heterogeneity, and Deeks' funnel plot asymmetry test indicated no potential publication bias (P = .09).

CONCLUSIONS

The meta-analysis indicated that circulating exosomes could serve as effective and minimally invasive biomarkers for diagnosis of cancer, especially in patients with hepatocellular carcinoma or ovarian cancer, serum-based samples and exosomal proteins.