PD-L1 on large extracellular vesicles is a predictive biomarker for therapy response in tissue PD-L1-low and -negative patients with non-small cell lung cancer.

Immunotherapy has revolutionized the treatment of patients with non-small cell lung cancer (NSCLC). High expression of tissue PD-L1 (tPD-L1) is currently the only approved biomarker for predicting treatment response. However, even tPD-L1 low (1-49%) and absent (<1%) patients might benefit from immunotherapy but, to date, there is no reliable biomarker, that can predict response in this particular patient subgroup. This study aimed to test whether tumour-associated extracellular vesicles (EVs) could fill this gap. Using NSCLC cell lines, we identified a panel of tumour-related antigens that were enriched on large EVs (lEVs) compared to smaller EVs. The levels of lEVs carrying these antigens were significantly elevated in plasma of NSCLC patients (n = 108) and discriminated them from controls (n = 77). Among the tested antigens, we focused on programmed cell death ligand 1 (PD-L1), which is a well-known direct target for immunotherapy. In plasma lEVs, PD-L1 was mainly found on a population of CD45- /CD62P+ lEVs and thus seemed to be associated with platelet-derived vesicles. Patients with high baseline levels of PD-L1+ lEVs in blood showed a significantly better response to immunotherapy and prolonged survival. This was particularly true in the subgroup of NSCLC patients with low or absent tPD-L1 expression, thus identifying PD-L1-positive lEVs in plasma as a novel predictive and prognostic marker for immunotherapy.

A novel method to efficiently differentiate human osteoclasts from blood-derived monocytes.

BACKGROUND: Osteoclasts are the tissue-specific macrophage population of the bone and unique in their bone-resorbing activity. Hence, they are fundamental for bone physiology in health and disease. However, efficient protocols for the isolation and study of primary human osteoclasts are scarce. In this study, we aimed to establish a protocol, which enables the efficient differentiation of functional human osteoclasts from monocytes. RESULTS: Human monocytes were isolated through a double-density gradient from donor blood. Compared to standard differentiation schemes in polystyrene cell culture dishes, the yield of multinuclear osteoclasts was significantly increased upon initial differentiation of monocytes to macrophages in fluorinated ethylene propylene (FEP) Teflon bags. This initial differentiation phase was then followed by the development of terminal osteoclasts by addition of Receptor Activator of NF-κB Ligand (RANKL). High concentrations of RANKL and Macrophage colony-stimulating factor (M-CSF) as well as an intermediate cell density further supported efficient cell differentiation. The generated cells were highly positive for CD45, CD14 as well as the osteoclast markers CD51/ITGAV and Cathepsin K/CTSK, thus identifying them as osteoclasts. The bone resorption of the osteoclasts was significantly increased when the cells were differentiated from macrophages derived from Teflon bags compared to macrophages derived from conventional cell culture plates. CONCLUSION: Our study has established a novel protocol for the isolation of primary human osteoclasts that improves osteoclastogenesis in comparison to the conventionally used cultivation approach.

Patient-reported outcomes in advanced NSCLC before and during the COVID-19 pandemic: Real-world data from the German prospective CRISP Registry (AIO-TRK-0315).

Patients with lung cancer under treatment have been associated with a high risk of COVID-19 infection and potentially worse outcome, but real-world data on patient-reported outcomes (PROs) are rare. We assess patients' characteristics and PROs before and during the COVID-19 pandemic in an advanced non-small cell lung cancer (NSCLC) cohort in Germany. Patients with locally advanced or metastatic NSCLC from the prospective, multicentre, observational CRISP Registry (NCT02622581) were categorised as pre-pandemic (March 2019 to Feb 2020, n = 1621) and pandemic (March 2020 to Feb 2021, n = 1317). From baseline to month 15, patients' health-related quality of life (HRQoL) was assessed by FACT-L, anxiety and depression by PHQ-4. Association of pandemic status with time to deterioration (TTD) in QoL scales adjusted for potential covariates was estimated using Cox modelling. PROs were documented for 1166 patients (72%) in the pre-pandemic, 979 (74%) in the pandemic group. Almost 60% of patients were male, median age was 66 years, comorbidities occurred in 85%. Regarding HRQoL, mean-change-from-baseline plots hardly differed between both samples. Approximately 15%-21% of patients reported anxiety, about 19%-27% signs of depression. For the pandemic group, TTD was slightly, but statistically significantly, worse for the physical well-being-FACT-G subscale (HR 1.15 [95%CI 1.02-1.30]) and the anxiety-GAD-2 subscale (HR 1.14 [95%CI 1.01-1.29]). These prospectively collected real-world data provide valuable insights into PROs before and during the COVID-19 pandemic in advanced NSCLC. For the patients, the pandemic seemed to be less of a burden than the disease itself, as there was a considerable proportion of patients with anxiety and depression in both groups.

Proteomic analysis of decellularized mice liver and kidney extracellular matrices.

BACKGROUND: The extracellular matrix (ECM) is a three-dimensional network of proteins that encases and supports cells within a tissue and promotes physiological and pathological cellular differentiation and functionality. Understanding the complex composition of the ECM is essential to decrypt physiological processes as well as pathogenesis. In this context, the method of decellularization is a useful technique to eliminate cellular components from tissues while preserving the majority of the structural and functional integrity of the ECM. RESULTS: In this study, we employed a bottom-up proteomic approach to elucidate the intricate network of proteins in the decellularized extracellular matrices of murine liver and kidney tissues. This approach involved the use of a novel, perfusion-based decellularization protocol to generate acellular whole organ scaffolds. Proteomic analysis of decellularized mice liver and kidney ECM scaffolds revealed tissue-specific differences in matrisome composition, while we found a predominantly stable composition of the core matrisome, consisting of collagens, glycoproteins, and proteoglycans. Liver matrisome analysis revealed unique proteins such as collagen type VI alpha-6, fibrillin-2 or biglycan. In the kidney, specific ECM-regulators such as cathepsin z were detected. CONCLUSION: The identification of distinct proteomic signatures provides insights into how different matrisome compositions might influence the biological properties of distinct tissues. This experimental workflow will help to further elucidate the proteomic landscape of decellularized extracellular matrix scaffolds of mice in order to decipher complex cell-matrix interactions and their contribution to a tissue-specific microenvironment.

Deep learning predicts therapy-relevant genetics in acute myeloid leukemia from Pappenheim-stained bone marrow smears.

ABSTRACT: The detection of genetic aberrations is crucial for early therapy decisions in acute myeloid leukemia (AML) and recommended for all patients. Because genetic testing is expensive and time consuming, a need remains for cost-effective, fast, and broadly accessible tests to predict these aberrations in this aggressive malignancy. Here, we developed a novel fully automated end-to-end deep learning pipeline to predict genetic aberrations directly from single-cell images from scans of conventionally stained bone marrow smears already on the day of diagnosis. We used this pipeline to compile a multiterabyte data set of >2 000 000 single-cell images from diagnostic samples of 408 patients with AML. These images were then used to train convolutional neural networks for the prediction of various therapy-relevant genetic alterations. Moreover, we created a temporal test cohort data set of >444 000 single-cell images from further 71 patients with AML. We show that the models from our pipeline can significantly predict these subgroups with high areas under the curve of the receiver operating characteristic. Potential genotype-phenotype links were visualized with 2 different strategies. Our pipeline holds the potential to be used as a fast and inexpensive automated tool to screen patients with AML for therapy-relevant genetic aberrations directly from routine, conventionally stained bone marrow smears already on the day of diagnosis. It also creates a foundation to develop similar approaches for other bone marrow disorders in the future.

Predictors of lower exercise capacity in patients with cancer.

Maintaining cancer patients' exercise capacity and therefore patients' ability to live a self-determined life is of huge importance, but little is known about major determinants. We sought to identify determinants of exercise capacity in patients with a broad spectrum of cancer types, who were already receiving cancer treatment or about to commence such therapy. Exercise capacity was assessed in 253 consecutive patients mostly suffering from advanced cancer using the 6-min walk test (6-MWT). All patients underwent echocardiography, physical examination, resting electrocardiogram, hand grip strength (HGS) measurement, and laboratory assessments. Patients were divided into two groups according to the median distance in the 6-MWT (459 m). Patients with lower exercise capacity were older, had significantly lower HGS and haemoglobin and higher values of high sensitive (hs) Troponin T and NT-proBNP (all p < 0.05). Whilst the co-morbidity burden was significantly higher in this group, no differences were detected for sex, body mass index, tumor type, or cachexia (all p > 0.2). Using multivariable logistic regression, we found that the presence of anaemia (odds ratio (OR) 6.172, 95% confidence interval (CI) 1.401-27.201, p = 0.016) as well as an increase in hs Troponin T (OR 3.077, 95% CI 1.202-5.301, p = 0.019) remained independent predictors of impaired exercise capacity. Increasing HGS was associated with a reduced risk of a lower exercise capacity (OR 0.896, 95% CI 0.813-0.987, p = 0.026). Screening patients for elevated hs troponin levels as well as reduced HGS may help to identify patients at risk of lower exercise capacity during cancer treatment.

Reduction of tumor volume during radiotherapy in patients with small-cell lung cancer and its prognostic significance.

BACKGROUND: Several studies have reported the potential prognostic significance of tumor volume reduction ratio (VRR) induced by radiotherapy (RT) in patients with non-small-cell lung cancer. However, there are no data yet on the prognostic significance of volumetric shrinkage in patients with small-cell lung cancer (SCLC). This study aimed to demonstrate the correlation between tumor volume reduction ratio and treatment outcomes. MATERIALS AND METHODS: The study included 61 patients with SCLC treated with fractionated RT of the primary tumor at our institution between 2013 and 2020. The relationship between volumetric changes in gross tumor volume (GTV) during radiotherapy and outcomes were analyzed and reported. RESULTS: The median radiation dose was 59.4 Gy (median fraction dose was 1.8 Gy). The median GTV before radiotherapy was 74 cm3, with a median GTV reduction of 48%. There was a higher VRR in patients receiving concurrent radiochemotherapy (p = 0.05). No volumetric parameters were identified as relevant predictors of outcome in the entire cohort. In multivariate analysis, only age had an impact on survival, while prophylactic whole-brain radiation influenced the progression-free survival significantly. CONCLUSION: Concurrent chemotherapy was associated with a higher VRR than sequential chemotherapy. No significant impact of VRR on patients' outcome or survival was detected.

Complete Metabolic Response to Combined Immune Checkpoint Inhibition after Progression of Metastatic Colorectal Cancer on Pembrolizumab: A Case Report.

DNA mismatch repair deficient (dMMR) and microsatellite instable (MSI) metastatic colorectal cancer (mCRC) can be successfully treated with FDA- and EMA-approved immune checkpoint inhibitors (ICI) pembrolizumab and nivolumab (as single agents targeting the anti-programmed cell death protein-1 (PD-1)) or combinations of a PD-1 inhibitor with ipilimumab, a cytotoxic T-lymphocyte-associated protein 4 (CTLA-4)-targeting antibody. The best treatment strategy beyond progression on single-agent ICI therapy remains unclear. Here, we present the case of a 63-year-old male with Lynch-syndrome-associated, microsatellite instability-high (MSI-H) mCRC who achieved a rapid normalization of his tumor markers and a complete metabolic remission (CMR), currently lasting for ten months, on sequential ICI treatment with the combination of nivolumab and ipilimumab followed by nivolumab maintenance therapy after progression on single-agent anti-PD-1 ICI therapy. The therapy was well-tolerated, and no immune-related adverse events occurred. To the best of our knowledge, this is the first case of a sustained metabolic complete remission in an MSI-H mCRC patient initially progressing on single-agent anti-PD-1 therapy. Thus, dMMR mCRC patients might benefit from sequential immune checkpoint regimens even with long-term responses. However, further sophistication of clinical algorithms for treatment beyond progression on single-agent ICI therapy in MSI-mCRC is urgently needed.

Extracellular vesicle-associated tyrosine kinase-like orphan receptors ROR1 and ROR2 promote breast cancer progression.

BACKGROUND: Extracellular vesicles (EVs) harbor a plethora of different biomolecules, which they can transport across cells. In cancer, tumor-derived EVs thereby support the creation of a favorable tumor microenvironment. So far, EV uptake and cargo delivery into target cells have been regarded as the main mechanisms for the pro-tumoral function of EVs. To test this hypothesis, we investigated the fate of the oncogenic transmembrane Wnt tyrosine kinase-like orphan receptor 1 and 2 (ROR1, ROR2) delivered via distinct EV subpopulations to breast cancer cells and aimed to unravel their impact on tumor progression. METHODS: EVs were isolated by differential ultracentrifugation from cell culture supernatant as well as plasma samples from healthy individuals (n = 27) and breast cancer patients (n = 41). EVs were thoroughly characterized by electron microscopy, nanoparticle tracking analysis, immunoblot, and flow cytometry. ROR transfer to target cells was observed using microscopy-based assays and biodistribution experiments were conducted in syngeneic mice. EV impact on cancer cell migration and invasion was tested in functional assays. RESULTS: We observed that the supernatant of ROR-overexpressing cells was sufficient for transferring the receptors to ROR-negative cells. Analyzing the secretome of the ROR-overexpressing cells, we detected a high enrichment of ROR1/2 on large and small EVs, but not on large oncosomes. Interestingly, the majority of ROR-positive EVs remained attached to the target cell surface after 24 h of stimulation and was quickly removed by treatment with trypsin. Nonetheless, ROR-positive EVs increased migration and invasion of breast cancer cells, even after chemically inhibiting EV uptake, in dependence of RhoA downstream signaling. In vivo, ROR-depleted EVs tended to distribute less into organs prone for the formation of breast cancer metastases. ROR-positive EVs were also significantly elevated in the plasma of breast cancer patients and allowed to separate them from healthy controls. CONCLUSIONS: The oncogenic Wnt receptors ROR1/2 are transferred via EVs to the surface of ROR-negative cancer cells, in which they induce an aggressive phenotype supporting tumor progression. Video Abstract.

BRD4 inhibition sensitizes diffuse large B-cell lymphoma cells to ferroptosis.

Diffuse large B-cell lymphoma (DLBCL), the most common form of non-Hodgkin lymphoma, is characterized by an aggressive clinical course. In approximately one-third of patients with DLBCL, first-line multiagent immunochemotherapy fails to produce a durable response. Molecular heterogeneity and apoptosis resistance pose major therapeutic challenges in DLBCL treatment. To circumvent apoptosis resistance, the induction of ferroptosis might represent a promising strategy for lymphoma therapy. In this study, a compound library, targeting epigenetic modulators, was screened to identify ferroptosis-sensitizing drugs. Strikingly, bromodomain and extra-terminal domain (BET) inhibitors sensitized cells of the germinal center B-cell-like (GCB) subtype of DLBCL to ferroptosis induction and the combination of BET inhibitors with ferroptosis inducers, such as dimethyl fumarate or RSL3, synergized in the killing of DLBCL cells in vitro and in vivo. On the molecular level, the BET protein BRD4 was found to be an essential regulator of ferroptosis suppressor protein 1 expression and thus to protect GCB-DLBCL cells from ferroptosis. Collectively, we identified and characterized BRD4 as an important player in ferroptosis suppression in GCB-DLBCL and provide a rationale for the combination of BET inhibitors with ferroptosis-inducing agents as a novel therapeutic approach for DLBCL treatment.

Rationale and Design of the Phase II ANTELOPE Study of Atezolizumab, Carboplatin and nab-Paclitaxel vs. Pembrolizumab, Platinum and Pemetrexed in TTF-1 Negative, Metastatic Lung Adenocarcinoma (AIO-TRK-0122).

INTRODUCTION: Pemetrexed-based immunochemotherapy represents an established standard of care as first line treatment for non-oncogenic driven metastatic non-small cell lung adenocarcinoma (NSCLC/ADC). However, retrospective analyses revealed better outcomes for pemetrexed-free regimens compared to pemetrexed-containing regimens in patients with thyroid transcription factor 1 (TTF-1) negative NSCLC/ADC. The multicenter, phase II, randomized, open-label ANTELOPE trial evaluates whether atezolizumab, carboplatin and nab-paclitaxel is superior to pembrolizumab, cis-/carboplatin and pemetrexed in TTF-1 negative NSCLC/ADC. METHODS: Eligible participants are ≥18 years of age, with histologically or cytologically confirmed, treatment-naïve stage IV TTF-1 negative NSCLC/ADC without actionable genomic alterations or PD-L1-overexpression (TPS ≥50%) and will be randomized in a 1:1 fashion to pemetrexed-free (group A) vs. pemetrexed-based (group B) immunochemotherapy. The primary endpoint of this trial is overall survival (OS). RESULTS: Enrollment will start in Q2 2023 at 30 sites in Germany with a planned inclusion of 136 participants. CONCLUSION: ANTELOPE will provide efficacy outcomes of the current standard-of-care for the specific subset of TTF-1 negative NSCLC/ADC in a head-to-head comparison of approved immunochemotherapy regimens.

High expression of transcription factor POU2F1 confers improved survival on smokers with lung adenocarcinoma: a retrospective study of two cohorts.

Background: Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related mortality worldwide and its most important risk factor is tobacco smoking. While smoking is associated with inferior outcome in NSCLC patients, smoking also correlates with a higher tumor mutational burden. In contrast to adenocarcinomas (ADC) of non-smokers, that frequently harbor targetable gain-of-function mutations, NSCLC smokers largely present with non-targetable loss-of-function mutations of genes associated with DNA-damage repair. The transcription factor Pit-1, Oct1/2, Unc-86 (POU) domain class 2 transcription factor 1 (POU2F1) is a widely expressed bipotential stabilizer of repressed and inducible transcriptional states and frequently deregulated in cancer. Methods: Via immunohistochemistry, we evaluated POU2F1 protein expression on a tissue micro array of 217 operable stage I-III NSCLC patients. Findings were reproduced in a gene expression database of 1144 NSCLC patients, filtered for POU2F1 mRNA expression. After retroviral overexpression of POU2F1 in A549 cells, we evaluated for clonogenic growth and proliferation. Additionally, CRISPR-Cas9 mediated POU2F1 knockdown in A549 cells was likewise analyzed. Results: High protein expression of POU2F1 in 217 NSCLC patients resulted in improved outcome of smokers with ADC [hazard ratio (HR) 0.30 (0.09-0.99), P=0.035]. Moreover, gene expression analysis confirmed favorable outcome of high POU2F1 mRNA expression in smokers with ADC [HR 0.41 (0.24-0.69), P<0.001]. Other than that, retrovirally induced overexpression of POU2F1 in A549 cells significantly reduced both, clonogenic growth as well as proliferation of NSCLC cells, whereas CRISPR-Cas9 mediated knockdown of the protein did not have any impact. Conclusions: Our data suggest that high expression of POU2F1 mediates a less aggressive cancer phenotype in smokers with ADC NSCLC. Pharmacological induction of genes and signaling pathways controlled by POU2F1 may provide novel avenues for future targeted NSCLC therapies in smokers.

Radiomics of Tumor Heterogeneity in 18F-FDG-PET-CT for Predicting Response to Immune Checkpoint Inhibition in Therapy-Naïve Patients with Advanced Non-Small-Cell Lung Cancer.

We aimed to evaluate the predictive and prognostic value of baseline 18F-FDG-PET-CT (PET-CT) radiomic features (RFs) for immune checkpoint-inhibitor (CKI)-based first-line therapy in advanced non-small-cell lung cancer (NSCLC) patients. In this retrospective study 44 patients were included. Patients were treated with either CKI-monotherapy or combined CKI-based immunotherapy-chemotherapy as first-line treatment. Treatment response was assessed by the Response Evaluation Criteria in Solid Tumors (RECIST). After a median follow-up of 6.4 months patients were stratified into "responder" (n = 33) and "non-responder" (n = 11). RFs were extracted from baseline PET and CT data after segmenting PET-positive tumor volume of all lesions. A Radiomics-based model was developed based on a Radiomics signature consisting of reliable RFs that allow classification of response and overall progression using multivariate logistic regression. These RF were additionally tested for their prognostic value in all patients by applying a model-derived threshold. Two independent PET-based RFs differentiated well between responders and non-responders. For predicting response, the area under the curve (AUC) was 0.69 for "PET-Skewness" and 0.75 predicting overall progression for "PET-Median". In terms of progression-free survival analysis, patients with a lower value of PET-Skewness (threshold < 0.2014; hazard ratio (HR) 0.17, 95% CI 0.06-0.46; p < 0.001) and higher value of PET-Median (threshold > 0.5233; HR 0.23, 95% CI 0.11-0.49; p < 0.001) had a significantly lower probability of disease progression or death. Our Radiomics-based model might be able to predict response in advanced NSCLC patients treated with CKI-based first-line therapy.

Metabolic Changes in Blood-derived Extracellular Vesicles of Malnourished Breast Cancer Patients.

BACKGROUND/AIM: Cancer cachexia describes a multifactorial wasting syndrome marked by a metabolic imbalance leading to the loss of muscle and fat tissue. Extracellular vesicles (EV) provide unique insights into their parental cells' metabolism. The value of these vesicles as diagnostic tools in cancer cachexia has not been investigated so far. PATIENTS AND METHODS: A previously analyzed metabolomics dataset on large EV from breast cancer patients was used for analyzing the metabolomic changes in patients with malnutrition. Follow-up time was 6 months. The data were analyzed using fold change analysis, volcano plotting, receiver operator characteristic (ROC) analysis, pathway analysis, and survival analysis. RESULTS: In patients with weight loss, statistical analysis revealed an increase in lysophosphatidylcholines (lysoPC a C16:0, lysoPC a C18:0, lysoPC a C18:1, lysoPC a C18:2, lysoPC a C20:4), sphingomyelins (SM (OH) C22:2 and SM C18:1), and phosphatidylcholines (PC aa C24:0, PC ae C34:3). When combined, these metabolites are a good predictor for cachexia in ROC curve analysis (AUC of 0.970; 95%CI=0.920-1.000; p<0.0001). Pathway analysis revealed an involvement of metabolites in "choline metabolism in cancer" and "glycerophospholipid metabolism". CONCLUSION: Large EV reflect metabolic changes in cancer patients suffering from cancer cachexia. Metabolic changes at the time of drawing blood were associated with the weight status (stable vs. weight loss) six months later and thereby could have a predictive impact.

Liquid Biopsies in Lung Cancer.

As lung cancer has the highest cancer-specific mortality rates worldwide, there is an urgent need for new therapeutic and diagnostic approaches to detect early-stage tumors and to monitor their response to the therapy. In addition to the well-established tissue biopsy analysis, liquid-biopsy-based assays may evolve as an important diagnostic tool. The analysis of circulating tumor DNA (ctDNA) is the most established method, followed by other methods such as the analysis of circulating tumor cells (CTCs), microRNAs (miRNAs), and extracellular vesicles (EVs). Both PCR- and NGS-based assays are used for the mutational assessment of lung cancer, including the most frequent driver mutations. However, ctDNA analysis might also play a role in monitoring the efficacy of immunotherapy and its recent accomplishments in the landscape of state-of-the-art lung cancer therapy. Despite the promising aspects of liquid-biopsy-based assays, there are some limitations regarding their sensitivity (risk of false-negative results) and specificity (interpretation of false-positive results). Hence, further studies are needed to evaluate the usefulness of liquid biopsies for lung cancer. Liquid-biopsy-based assays might be integrated into the diagnostic guidelines for lung cancer as a tool to complement conventional tissue sampling.

Reciprocal interactions between innate immune cells and astrocytes facilitate neuroinflammation and brain metastasis via lipocalin-2.

Brain metastasis still encompass very grim prognosis and therefore understanding the underlying mechanisms is an urgent need toward developing better therapeutic strategies. We uncover the intricate interactions between recruited innate immune cells and resident astrocytes in the brain metastatic niche that facilitate metastasis of melanoma and breast cancer. We show that granulocyte-derived lipocalin-2 (LCN2) induces inflammatory activation of astrocytes, leading to myeloid cell recruitment to the brain. LCN2 is central to inducing neuroinflammation as its genetic targeting or bone-marrow transplantation from LCN2-/- mice was sufficient to attenuate neuroinflammation and inhibit brain metastasis. Moreover, high LCN2 levels in patient blood and brain metastases in multiple cancer types were strongly associated with disease progression and poor survival. Our findings uncover a previously unknown mechanism, establishing a central role for the reciprocal interactions between granulocytes and astrocytes in promoting brain metastasis and implicate LCN2 as a prognostic marker and potential therapeutic target.

Extracellular Vesicles in Liquid Biopsies as Biomarkers for Solid Tumors.

Extracellular vesicles (EVs) are secreted by all living cells and are ubiquitous in every human body fluid. They are quite heterogeneous with regard to biogenesis, size, and composition, yet always reflect their parental cells with their cell-of-origin specific cargo loading. Since numerous studies have demonstrated that EV-associated proteins, nucleic acids, lipids, and metabolites can represent malignant phenotypes in cancer patients, EVs are increasingly being discussed as valuable carriers of cancer biomarkers in liquid biopsy samples. However, the lack of standardized and clinically feasible protocols for EV purification and characterization still limits the applicability of EV-based cancer biomarker analysis. This review first provides an overview of current EV isolation and characterization techniques that can be used to exploit patient-derived body fluids for biomarker quantification assays. Secondly, it outlines promising tumor-specific EV biomarkers relevant for cancer diagnosis, disease monitoring, and the prediction of cancer progression and therapy resistance. Finally, we summarize the advantages and current limitations of using EVs in liquid biopsy with a prospective view on strategies for the ongoing clinical implementation of EV-based biomarker screenings.