Extracellular vesicles and co-isolated endogenous retroviruses from murine cancer cells differentially affect dendritic cells.

Cells secrete extracellular vesicles (EVs) and non-vesicular extracellular (nano)particles (NVEPs or ENPs) that may play a role in intercellular communication. Tumor-derived EVs have been proposed to induce immune priming of antigen presenting cells or to be immuno-suppressive agents. We suspect that such disparate functions are due to variable compositions in EV subtypes and ENPs. We aimed to characterize the array of secreted EVs and ENPs of murine tumor cell lines. Unexpectedly, we identified virus-like particles (VLPs) from endogenous murine leukemia virus in preparations of EVs produced by many tumor cells. We established a protocol to separate small EVs from VLPs and ENPs. We compared their protein composition and analyzed their functional interaction with target dendritic cells. ENPs were poorly captured and did not affect dendritic cells. Small EVs specifically induced dendritic cell death. A mixed large/dense EV/VLP preparation was most efficient to induce dendritic cell maturation and antigen presentation. Our results call for systematic re-evaluation of the respective proportions and functions of non-viral EVs and VLPs produced by murine tumors and their contribution to tumor progression.

Pembrolizumab, radiotherapy, and an immunomodulatory five-drug cocktail in pretreated patients with persistent, recurrent, or metastatic cervical or endometrial carcinoma: Results of the phase II PRIMMO study.

A phase II study (PRIMMO) of patients with pretreated persistent/recurrent/metastatic cervical or endometrial cancer is presented. Patients received an immunomodulatory five-drug cocktail (IDC) consisting of low-dose cyclophosphamide, aspirin, lansoprazole, vitamin D, and curcumin starting 2 weeks before radioimmunotherapy. Pembrolizumab was administered three-weekly from day 15 onwards; one of the tumor lesions was irradiated (8Gyx3) on days 15, 17, and 19. The primary endpoint was the objective response rate per immune-related response criteria (irORR) at week 26 (a lower bound of the 90% confidence interval [CI] of > 10% was considered efficacious). The prespecified 43 patients (cervical, n = 18; endometrial, n = 25) were enrolled. The irORR was 11.1% (90% CI 2.0-31.0) in cervical cancer and 12.0% (90% CI 3.4-28.2) in endometrial cancer. Median duration of response was not reached in both cohorts. Median interval-censored progression-free survival was 4.1 weeks (95% CI 4.1-25.7) in cervical cancer and 3.6 weeks (95% CI 3.6-15.4) in endometrial cancer; median overall survival was 39.6 weeks (95% CI 15.0-67.0) and 37.4 weeks (95% CI 19.0-50.3), respectively. Grade ≥ 3 treatment-related adverse events were reported in 10 (55.6%) cervical cancer patients and 9 (36.0%) endometrial cancer patients. Health-related quality of life was generally stable over time. Responders had a significantly higher proportion of peripheral T cells when compared to nonresponders (p = 0.013). In conclusion, PRIMMO did not meet its primary objective in both cohorts; pembrolizumab, radiotherapy, and an IDC had modest but durable antitumor activity with acceptable but not negligible toxicity.Trial registration ClinicalTrials.gov (identifier NCT03192059) and EudraCT Registry (number 2016-001569-97).

Integrating automated liquid handling in the separation workflow of extracellular vesicles enhances specificity and reproducibility.

BACKGROUND: Extracellular vesicles (EV) are extensively studied in human body fluids as potential biomarkers for numerous diseases. Major impediments of EV-based biomarker discovery include the specificity and reproducibility of EV sample preparation as well as intensive manual labor. We present an automated liquid handling workstation for the density-based separation of EV from human body fluids and compare its performance to manual handling by (in)experienced researchers. RESULTS: Automated versus manual density-based separation of trackable recombinant extracellular vesicles (rEV) spiked in PBS significantly reduces variability in rEV recovery as quantified by fluorescent nanoparticle tracking analysis and ELISA. To validate automated density-based EV separation from complex body fluids, including blood plasma and urine, we assess reproducibility, recovery, and specificity by mass spectrometry-based proteomics and transmission electron microscopy. Method reproducibility is the highest in the automated procedure independent of the matrix used. While retaining (in urine) or enhancing (in plasma) EV recovery compared to manual liquid handling, automation significantly reduces the presence of body fluid specific abundant proteins in EV preparations, including apolipoproteins in plasma and Tamm-Horsfall protein in urine. CONCLUSIONS: In conclusion, automated liquid handling ensures cost-effective EV separation from human body fluids with high reproducibility, specificity, and reduced hands-on time with the potential to enable larger-scale biomarker studies.

Immunologic impact of chemoradiation in cervical cancer and how immune cell infiltration could lead toward personalized treatment.

We investigated the potential of tumor-infiltrating immune cells (ICs) as predictive or prognostic biomarkers for cervical cancer patients. In total, 38 patients treated with (chemo)radiotherapy and subsequent surgery were included in the current study. This unique treatment schedule makes it possible to analyze IC markers in pretreatment and posttreatment tissue specimens and their changes during treatment. IC markers for T cells (CD3, CD4, CD8 and FoxP3), macrophages (CD68 and CD163) and B cells (CD20), as well as IL33 and PD-L1, were retrospectively analyzed via immunohistochemistry. Patients were grouped in the low score or high score group based on the amount of positive cells on immunohistochemistry. Correlations to pathological complete response (pCR), cause-specific survival (CSS) and metastasis development during follow-up were evaluated. In analysis of pretreatment biopsies, significantly more pCR was seen for patients with CD8 = CD3, CD8 ≥ CD4, positive IL33 tumor cell (TC) scores, IL33 IC < TC and PD-L1 TC ≥5%. Besides patients with high CD8 scores, also patients with CD8 ≥ CD4, CD163 ≥ CD68 or PD-L1 IC ≥5% had better CSS. In the analysis of posttreatment specimens, less pCR was observed for patients with high CD8 or CD163 scores. Patients with decreasing CD8 or CD163 scores between pretreatment and posttreatment samples showed more pCR, whereas those with increasing CD8 or decreasing IL33 IC scores showed a worse CSS. Meanwhile, patients with an increasing CD3 score or stable/increasing PD-L1 IC score showed more metastasis during follow-up. In this way, the intratumoral IC landscape is a promising tool for prediction of outcome and response to (chemo)radiotherapy.

EV-TRACK: transparent reporting and centralizing knowledge in extracellular vesicle research.

We argue that the field of extracellular vesicle (EV) biology needs more transparent reporting to facilitate interpretation and replication of experiments. To achieve this, we describe EV-TRACK, a crowdsourcing knowledgebase (http://evtrack.org) that centralizes EV biology and methodology with the goal of stimulating authors, reviewers, editors and funders to put experimental guidelines into practice.

Splenic 18F-FDG uptake on baseline PET/CT is associated with oncological outcomes and tumor immune state in uterine cervical cancer.

OBJECTIVE: The spleen represents an important contributor to tumor immune escape, but the relevance of increased splenic metabolic activity remains to be fully elucidated. METHODS: We retrospectively measured the spleen-to-liver standard uptake value (SLR) on 18F-FDG PET/CT examinations of 92 consecutive patients with FIGO stage IB1 to IVA cervical cancer and integrated the results with survival, response to treatment, tumor immune infiltrate, and baseline characteristics. RESULTS: SLRmax > 0.92 (p = .026) and SLRmean > 0.94 (p = .005) were significantly associated with decreased DFS in univariable analysis. Multivariable models were built using best subset selection; ΔSLRmax and either SLRmax or SLRmean were consistently selected, strongly reinforcing the association between SLR variables and DFS in relation to potential confounders (all models p ≤ .002). Independent associations were found for SLRmax using multivariable Cox regression models for DFS (all p ≤ .003). Further, uni- and multivariable analyses demonstrated the negative impact of higher SLR values on pathological complete response. A statistically significant higher proportion of patients with high SLRmax had a dense infiltrate of CD20+ (p = .036) and CD68+ (p = .015) immune cells, as well as PD-L1+ tumor cells (p = .019) as compared to those with low SLRmax. Finally, high SLRmax status was neither associated with systemic inflammatory markers (except for an increased white blood cell count; p = .038), nor with clinically overt infection. CONCLUSION: This hypothesis-generating study provides the first evidence that increased splenic metabolic activity is a negative prognostic and predictive biomarker in locally advanced cervical cancer. In addition, it might help to discriminate immunologically 'hot' from 'cold' cervical tumors.

PRIMMO study protocol: a phase II study combining PD-1 blockade, radiation and immunomodulation to tackle cervical and uterine cancer.

BACKGROUND: Immunotherapeutic approaches have revolutionized oncological practice but are less evaluated in gynecological malignancies. PD-1/PD-L1 blockade in gynecological cancers showed objective responses in 13-17% of patients. This could be due to immunosuppressive effects exerted by gynecological tumors on the microenvironment and an altered tumor vasculature. In other malignancies, combining checkpoint blockade with radiation delivers benefit that is believed to be due to the abscopal effect. Addition of immune modulation agents has also shown to enhance immune checkpoint blockade efficacy. Therefore we designed a regimen consisting of PD-1 blockade combined with radiation, and different immune/environmental-targeting compounds: repurposed drugs, metronomic chemotherapy and a food supplement. We hypothesize that these will synergistically modulate the tumor microenvironment and induce and sustain an anti-tumor immune response, resulting in tumor regression. METHODS: PRIMMO is a multi-center, open-label, non-randomized, 3-cohort phase 2 study with safety run-in in patients with recurrent/refractory cervical carcinoma, endometrial carcinoma or uterine sarcoma. Treatment consists of daily intake of vitamin D, lansoprazole, aspirin, cyclophosphamide and curcumin, starting 2 weeks before the first pembrolizumab dose. Pembrolizumab is administered 3-weekly for a total of 6 cycles. Radiation (3 × 8 Gy) is given on days 1, 3 and 5 of the first pembrolizumab dose. The safety run-in consists of 6 patients. In total, 18 and 25 evaluable patients for cervical and endometrial carcinoma respectively are foreseen to enroll. No sample size is determined for uterine sarcoma due to its rarity. The primary objective is objective response rate at week 26 according to immune-related response criteria. Secondary objectives include safety, objective response rate at week 26 according to RECIST v1.1, best overall response, progression-free survival, overall survival and quality of life. Exploratory, translational research aims to evaluate immune biomarkers, extracellular vesicles, cell death biomarkers and the gut microbiome. DISCUSSION: In this study, a combination of PD-1 blockade, radiation and immune/environmental-targeting compounds is tested, aiming to tackle the tumor microenvironment and induce anti-tumor immunity. Translational research is performed to discover biomarkers related to the mode of action of the combination. TRIAL REGISTRATION: EU Clinical Trials Register: EudraCT 2016-001569-97 , registered on 19-6-2017. Clinicaltrials.gov: NCT03192059 , registered on 19-6-2017.

Identification and validation of extracellular vesicle reference genes for the normalization of RT-qPCR data.

Extracellular vesicles (EVs) contain a plethora of biomolecules, including nucleic acids, with diverse diagnostic and therapeutic application potential. Although reverse transcription-quantitative PCR (RT-qPCR) is the most widely applied laboratory technique to evaluate gene expression, its applicability in EV research is challenged by the lack of universal and stably present reference genes (RGs). In this study, we identify, validate and establish SNRPG, OST4, TOMM7 and NOP10 as RGs for the normalization of EV-associated genes by RT-qPCR. We show the stable presence of SNRPG, OST4, TOMM7 and NOP10 in multiple cell lines and their secreted EVs (n = 12) under different (patho)physiological conditions as well as in human-derived biofluids (n = 3). Enzymatic treatments confirm the presence of SNRPG, OST4, TOMM7 and NOP10 inside EVs. In addition, the four EV-associated RGs are stably detected in a size-range of EV subpopulations. RefFinder analysis reveals that SNRPG, OST4, TOMM7 and NOP10 are more stable compared to RGs established specifically for cultured cells or tissues such as HMBS, YWHAZ, SDHA and GAPDH. In summary, we present four universal and stably present EV-associated RGs to enable normalization and thus steer the implementation of RT-qPCR for the analysis of EV-associated RNA cargo for research or clinical applications.

International Society for Extracellular Vesicles Workshop. QuantitatEVs: multiscale analyses, from bulk to single extracellular vesicle.

The 'QuantitatEVs: multiscale analyses, from bulk to single vesicle' workshop aimed to discuss quantitative strategies and harmonized wet and computational approaches toward the comprehensive analysis of extracellular vesicles (EVs) from bulk to single vesicle analyses with a special focus on emerging technologies. The workshop covered the key issues in the quantitative analysis of different EV-associated molecular components and EV biophysical features, which are considered the core of EV-associated biomarker discovery and validation for their clinical translation. The in-person-only workshop was held in Trento, Italy, from January 31st to February 2nd, 2023, and continued in Milan on February 3rd with "Next Generation EVs", a satellite event dedicated to early career researchers (ECR). This report summarizes the main topics and outcomes of the workshop.

Association of Cell Death Markers With Tumor Immune Cell Infiltrates After Chemo-Radiation in Cervical Cancer.

Irradiation induces distinct cellular responses such as apoptosis, necroptosis, iron-dependent cell death (a feature of ferroptosis), senescence, and mitotic catastrophe. Several of these outcomes are immunostimulatory and may represent a potential for immunogenic type of cell death (ICD) induced by radiotherapy triggering abscopal effects. The purpose of this study is to determine whether intra-tumoral ICD markers can serve as biomarkers for the prediction of patient's outcomes defined as the metastasis status and survival over a 5-year period. Thirty-eight patients with locally advanced cervical cancer, treated with neoadjuvant chemoradiotherapy using cisplatin were included in this study. Pre-treatment tumor biopsy and post-treatment hysterectomy samples were stained for cell death markers and danger associated molecular patterns (DAMPs): cleaved caspase-3 (apoptosis), phosphorylated mixed lineage kinase domain like pseudokinase (pMLKL; necroptosis), glutathione peroxidase 4 (GPX4; ferroptosis) and 4-hydroxy-2-noneal (4-HNE; ferroptosis), high mobility group box 1 (HMGB1) and calreticulin. Although these markers could not predict the patient's outcome in terms of relapse or survival, many significantly correlated with immune cell infiltration. For instance, inducing ferroptosis post-treatment seems to negatively impact immune cell recruitment. Measuring ICD markers could reflect the impact of treatment on the tumor microenvironment with regard to immune cell recruitment and infiltration. One Sentence Summary: Cell death readouts during neoadjuvant chemoradiation in cervical cancer.

Recombinant extracellular vesicles as biological reference material for method development, data normalization and assessment of (pre-)analytical variables.

The diagnostic and therapeutic use of extracellular vesicles (EV) is under intense investigation and may lead to societal benefits. Reference materials are an invaluable resource for developing, improving and assessing the performance of regulated EV applications and for quantitative and objective data interpretation. We have engineered recombinant EV (rEV) as a biological reference material. rEV have similar biochemical and biophysical characteristics to sample EV and function as an internal quantitative and qualitative control throughout analysis. Spiking rEV in bodily fluids prior to EV analysis maps technical variability of EV applications and promotes intra- and inter-laboratory studies. This protocol, which is an Extension to our previously published protocol (Tulkens et al., 2020), describes the production, separation and quality assurance of rEV, their dilution and addition to bodily fluids, and the detection steps based on complementary fluorescence, nucleic acid and protein measurements. We demonstrate the use of rEV for method development, data normalization and assessment of pre-analytical variables. The protocol can be adopted by researchers with standard laboratory and basic EV separation/characterization experience and requires ~4-5 d.

Unravelling the proteomic landscape of extracellular vesicles in prostate cancer by density-based fractionation of urine.

Extracellular vesicles (EV) are increasingly being recognized as important vehicles of intercellular communication and promising diagnostic and prognostic biomarkers in cancer. Despite this enormous clinical potential, the plethora of methods to separate EV from biofluids, providing material of highly variable purity, and lacking knowledge regarding methodological repeatability pose a barrier to clinical translation. Urine is considered an ideal proximal fluid for the study of EV in urological cancers due to its direct contact with the urogenital system. We demonstrate that density-based fractionation of urine by bottom-up Optiprep density gradient centrifugation separates EV and soluble proteins with high specificity and repeatability. Mass spectrometry-based proteomic analysis of urinary EV (uEV) in men with benign and malignant prostate disease allowed us to significantly expand the known human uEV proteome with high specificity and identifies a unique biological profile in prostate cancer not uncovered by the analysis of soluble proteins. In addition, profiling the proteome of EV separated from prostate tumour conditioned medium and matched uEV confirms the specificity of the identified uEV proteome for prostate cancer. Finally, a comparative proteomic analysis with uEV from patients with bladder and renal cancer provided additional evidence of the selective enrichment of protein signatures in uEV reflecting their respective cancer tissues of origin. In conclusion, this study identifies hundreds of previously undetected proteins in uEV of prostate cancer patients and provides a powerful toolbox to map uEV content and contaminants ultimately allowing biomarker discovery in urological cancers.

The generation and use of recombinant extracellular vesicles as biological reference material.

Recent years have seen an increase of extracellular vesicle (EV) research geared towards biological understanding, diagnostics and therapy. However, EV data interpretation remains challenging owing to complexity of biofluids and technical variation introduced during sample preparation and analysis. To understand and mitigate these limitations, we generated trackable recombinant EV (rEV) as a biological reference material. Employing complementary characterization methods, we demonstrate that rEV are stable and bear physical and biochemical traits characteristic of sample EV. Furthermore, rEV can be quantified using fluorescence-, RNA- and protein-based technologies available in routine laboratories. Spiking rEV in biofluids allows recovery efficiencies of commonly implemented EV separation methods to be identified, intra-method and inter-user variability induced by sample handling to be defined, and to normalize and improve sensitivity of EV enumerations. We anticipate that rEV will aid EV-based sample preparation and analysis, data normalization, method development and instrument calibration in various research and biomedical applications.