The majority of extracellular vesicle (EV) studies conducted to date have been performed on cell lines with little knowledge on how well these represent the characteristics of EVs in vivo . The aim of this study was to establish a method to isolate and categorize subpopulations of EVs isolated directly from tumour tissue. First we established an isolation protocol for subpopulations of EVs from metastatic melanoma tissue, which included enzymatic treatment (collagenase D and DNase). Small and large EVs were isolated with differential ultracentrifugation, and these were further separated into high and low‐density (HD and LD) fractions. All EV subpopulations were then analysed in depth using electron microscopy, Bioanalyzer®, nanoparticle tracking analysis, and quantitative mass spectrometry analysis. Subpopulations of EVs with distinct size, morphology, and RNA and protein cargo could be isolated from the metastatic melanoma tissue. LD EVs showed an RNA profile with the presence of 18S and 28S ribosomal subunits. In contrast, HD EVs had RNA profiles with small or no peaks for ribosomal RNA subunits. Quantitative proteomics showed that several proteins such as flotillin‐1 were enriched in both large and small LD EVs, while ADAM10 were exclusively enriched in small LD EVs. In contrast, mitofilin was enriched only in the large EVs. We conclude that enzymatic treatments improve EV isolation from dense fibrotic tissue without any apparent effect on molecular or morphological characteristics. By providing a detailed categorization of several subpopulations of EVs isolated directly from tumour tissues, we might better understand the function of EVs in tumour biology and their possible use in biomarker discovery.

Extracellular vesicles (EVs), including exosomes and microvesicles, are secreted from all cells, and convey messages between cells in health and disease. However, the diversity of EV subpopulations is only beginning to be explored. Since EVs have been implicated in tumour microenvironmental communication, we started to determine the diversity of EVs specifically in this tissue. To do this, we isolated EVs directly from patient melanoma metastatic tissues. Using EV membrane isolation and mass spectrometry analysis, we discovered enrichment of mitochondrial membrane proteins in the melanoma tissue‐derived EVs, compared to non‐melanoma‐derived EVs. Interestingly, two mitochondrial inner membrane proteins MT‐CO2 (encoded by the mitochondrial genome) and COX6c (encoded by the nuclear genome) were highly prevalent in the plasma of melanoma patients, as well as in ovarian and breast cancer patients. Furthermore, this subpopulation of EVs contains active mitochondrial enzymes. In summary, tumour tissues are enriched in EVs with mitochondrial membrane proteins and these mitochondrial membrane proteins can be detected in plasma and are increased in melanoma, ovarian cancer as well as breast cancer.

The role of axillary lymph node dissection (ALND) has increasingly been called into question among patients with positive sentinel lymph nodes. Two recent trials have failed to show a survival difference in sentinel node-positive breast cancer patients who were randomized either to undergo completion ALND or not. Neither of the trials, however, included breast cancer patients undergoing mastectomy or those with tumors larger than 5 cm, and power was debatable to show a small survival difference. The prospective randomized SENOMAC trial includes clinically node-negative breast cancer patients with up to two macrometastases in their sentinel lymph node biopsy. Patients with T1-T3 tumors are eligible as well as patients prior to systemic neoadjuvant therapy. Both breast-conserving surgery and mastectomy, with or without breast reconstruction, are eligible interventions. Patients are randomized 1:1 to either undergo completion ALND or not by a web-based randomization tool. This trial is designed as a non-inferiority study with breast cancer-specific survival at 5 years as the primary endpoint. Target accrual is 3500 patients to achieve 80% power in being able to detect a potential 2.5% deterioration of the breast cancer-specific 5-year survival rate. Follow-up is by annual clinical examination and mammography during 5 years, and additional controls after 10 and 15 years. Secondary endpoints such as arm morbidity and health-related quality of life are measured by questionnaires at 1, 3 and 5 years. Several large subgroups of breast cancer patients, such as patients undergoing mastectomy or those with larger tumors, have not been included in key trials; however, the use of ALND is being questioned even in these groups without the support of high-quality evidence. Therefore, the SENOMAC Trial will investigate the need of completion ALND in case of limited spread to the sentinel lymph nodes not only in patients undergoing any breast surgery, but also in neoadjuvantly treated patients and patients with larger tumors. NCT 02240472 , retrospective registration date September 14, 2015 after trial initiation on January 31, 2015.

Metastatic uveal melanoma is less well understood than its primary counterpart, has a distinct biology compared to skin melanoma, and lacks effective treatments. Here we genomically profile metastatic tumors and infiltrating lymphocytes. BAP1 alterations are overrepresented and found in 29/32 of cases. Reintroducing a functional BAP1 allele into a deficient patient-derived cell line, reveals a broad shift towards a transcriptomic subtype previously associated with better prognosis of the primary disease. One outlier tumor has a high mutational burden associated with UV-damage. CDKN2A deletions also occur, which are rarely present in primaries. A focused knockdown screen is used to investigate overexpressed genes associated withcopy number gains. Tumor-infiltrating lymphocytes are in several cases found tumor-reactive, but expression of the immune checkpoint receptors TIM-3, TIGIT and LAG3 is also abundant. This study represents the largest whole-genome analysis of uveal melanoma to date, and presents an updated view of the metastatic disease.