First evidence of AXL expression on circulating tumor cells in metastatic breast cancer patients: A proof-of-concept study.

BACKGROUND: For several years, the AXL tyrosine kinase receptor, a member of the Tyro3-Axl-Mer (TAM) family, has been considered a new strategic target in oncology. AXL overexpression is common in solid tumors and is associated with poor prognosis. In this context, the detection of a subset of circulating tumor cells (CTCs) that express AXL (AXL+ CTCs) could be clinically relevant. METHODS: Immunostaining was performed to assess AXL expression in human breast cancer cell lines. The optimal conditions were established using flow cytometry. Spiking experiments were carried out to optimize the parameters of the CellSearch® system detection test. CTC enumeration and AXL expression were evaluated in patients with metastatic breast cancer (mBC) before treatment initiation. RESULTS: An innovative AXL+ CTC detection assay to be used with the CellSearch® system was developed. In a prospective longitudinal clinical trial, blood samples from 60 patients with untreated mBC were analyzed to detect AXL+ CTCs with this new assay. CTCs were detected in 35/60 patients (58.3%) and AXL+ CTCs were identified in 7 of these 35 patients (11.7% of all patients). CONCLUSION: This newly established AXL+ CTC assay is a promising tool that can be used for liquid biopsy in future clinical trials to stratify and monitor patients with cancer receiving anti-AXL therapies.

Contraception in breast cancer survivors from the FEERIC case-control study (performed on behalf of the Seintinelles research network).

OBJECTIVE: To compare the prevalence of contraception in breast cancer (BC) patients at risk of unintentional pregnancy (i.e. not currently pregnant or trying to get pregnant) and matched controls. STUDY DESIGN: The FEERIC study (Fertility, Pregnancy, Contraception after BC in France) is a prospective, multicenter case-control study, including localized BC patients aged 18-43 years, matched for age and parity to cancer-free volunteer controls in a 1:2 ratio. Data were collected through online questionnaires completed on the Seintinelles research platform. RESULTS: In a population of 1278 women at risk of unintentional pregnancy, the prevalence of contraception at study inclusion did not differ significantly between cases (340/431, 78.9%) and controls (666/847, 78.6%, p = 0.97). Contrarily, the contraceptive methods used were significantly different, with a higher proportion of copper IUD use in BC survivors (59.5% versus 25.0% in controls p < 0.001). For patients at risk of unintentional pregnancy, receiving information about chemotherapy-induced ovary damage at BC diagnosis (OR = 2.47 95%CI [ 1.39-4.37] and anti-HER2 treatment (OR = 2.46, 95% CI [ 1.14-6.16]) were significantly associated with the use of a contraception in multivariate analysis. CONCLUSION: In this large French study, BC survivors had a prevalence of contraception use similar to that for matched controls, though almost one in five women at risk of unintentional pregnancy did not use contraception. Dedicated consultations at cancer care centers could further improve access to information and contraception counseling.

Correlation of the TIGIT-PVR immune checkpoint axis with clinicopathological features in triple-negative breast cancer.

Background: T cell immunoreceptor with Ig and ITIM domains (TIGIT) interacts with poliovirus receptor (PVR) to contribute to cancer immune escape. Recently, TIGIT and PVR have been identified as promising immunotherapy targets. Their gene expression is upregulated in many solid tumors, but their protein expression level is not well documented, particularly in triple negative breast cancer (TNBC), the breast cancer subtype that most benefit from immunotherapy. Methods: TIGIT and PVR expression levels were assessed by immunohistochemistry in 243 surgically resected localized TNBC and then their relationship with clinical-pathological features and clinical outcome was analyzed. Results: TIGIT expression was observed in immune cells from the tumor microenvironment, whereas PVR was mainly expressed by tumor cells. High TIGIT expression was significantly associated with age (p=0.010), histological grade (p=0.014), non-lobular histology (p=0.024), adjuvant chemotherapy (p=0.006), and various immune cell populations (tumor infiltrating lymphocytes (TILs), CD3+, CD8+, PD-1+ cells; all p<0.0001), PD-L1+ tumor cells (p<0.0001), and PD-L1+ stromal cells (p=0.003). Infiltration by TIGIT+ cells tended to be higher in non-molecular apocrine tumors (p=0.088). PVR was significantly associated with histological grade (p<0.0001), the basal-like (p=0.003) and non-molecular apocrine phenotypes (p=0.039), high TILs infiltration (p=0.011), CD3+ (p=0.002), CD8+ (p=0.024) T cells, and PD-L1 expression in tumor (p=0.003) and stromal cells (p=0.001). In univariate analysis, only known prognostic factors (age, tumor size, lymph node status, adjuvant chemotherapy, TILs and CD3+ T-cell infiltrate) were significantly associated with relapse-free survival (RFS) and overall survival. High TIGIT and PVR expression levels tended to be associated with longer RFS (p=0.079 and 0.045, respectively). The analysis that included only non-molecular apocrine TNBC revealed longer RFS for tumors that strongly expressed TIGIT or PVR (p=0.025 for TIGIT and 0.032 for PVR). Conclusions: These results indicated that in TNBC, TIGIT+ cells can easily interact with PVR to exert their inhibitory effects. Their wide expression in TNBC and their association with other immune checkpoint components suggest the therapeutic interest of the TIGIT-PVR axis.

Association of CD206 Protein Expression with Immune Infiltration and Prognosis in Patients with Triple-Negative Breast Cancer.

Background: Triple-negative breast cancers (TNBCs) have a worse prognosis, but might respond to immunotherapies. Macrophages are plastic cells that can adopt various phenotypes and functions. Although they are a major immune population in TNBCs, the relationship between tumor-associated macrophages (TAMs) and TNBC progression has been rarely explored, with controversial results. Methods: We evaluated the prognostic impact of TAMs, quantified by immunohistochemistry with anti-CD68, -IRF8, -CD163, and -CD206 antibodies, in a well-described cohort of 285 patients with non-metastatic TNBC. Results: CD68 (p = 0.008), IRF8 (p = 0.001), and CD163 (p < 0.001) expression positively correlated with higher tumor grade, while CD206 was associated with smaller tumor size (p < 0.001). All macrophage markers were associated with higher tumor-infiltrating lymphocyte numbers and PD-L1 expression. Univariate survival analyses reported a significant positive correlation between CD163+ or CD206+ TAMs and relapse-free survival (respectively: HR = 0.52 [0.28−0.97], p = 0.027, and HR = 0.51 [0.31−0.82], p = 0.005), and between CD206+ TAMs and overall survival (HR = 0.54 [0.35−0.83], p = 0.005). In multivariate analysis, there was a trend for an association between CD206+ TAMs and relapse-free survival (HR = 0.63 [0.33−1.04], p = 0.073). Conclusions: These data suggest that CD206 expression defines a TAM subpopulation potentially associated with favorable outcomes in patients with TNBC. CD206 expression might identify an immune TNBC subgroup with specific therapeutic options.

Pregnancy, fertility concerns and fertility preservation procedures in a national study of French breast cancer survivors.

RESEARCH QUESTION: What are the real-life oncofertility practices in young women diagnosed with breast cancer? DESIGN: The FEERIC (FErtility, prEgnancy, contRaceptIon after breast Cancer in France) study is a web-based cohort study launched with the French collaborative research platform Seintinelles. The current work is based on the enrolment self-administered questionnaire of 517 patients with prior breast cancer diagnosis, free from relapse and aged 18 to 43 years at inclusion (from 12 March 2018 to 27 June 2019). RESULTS: Median age at breast cancer diagnosis was 33.6 years and 424 patients (82.0%) received chemotherapy. Overall, 236 (45.6%) patients were offered specialized oncofertility counselling, 181 patients underwent at least one fertility preservation procedure (FPP); 125 (24.2%) underwent one or more FPP with material preservation (oocytes n = 108, 20.9%; embryos n = 31, 6.0%; ovarian cryopreservation n = 6, 1.2%) and 78 patients received gonadotrophin-releasing hormone agonists (15.1%). With a median follow-up of 26.9 months after the end of treatments, 133 pregnancies had occurred in 85 patients (16.4%), including 20 unplanned pregnancies (15.0%). Most of the pregnancies were natural conceptions (n = 113, 87.6%), while 16 (12.4%) required medical interventions. For the planned pregnancies, median time to the occurrence of an ongoing pregnancy was 3 months. Patients who had an unplanned pregnancy reported lower rates of information on the consequences of the treatments on fertility (P = 0.036) at diagnosis. CONCLUSIONS: Most of the patients were not offered proper specialized oncofertility counselling at the time of breast cancer diagnosis. Naturally conceived pregnancies after breast cancer were much more frequent than pregnancies resulting from the use of cryopreserved gametes. Adequate contraceptive counselling seems as important as information about fertility and might prevent unplanned pregnancies.

Sexual quality of life assessment in young women with breast cancer during adjuvant endocrine therapy and patient-reported supportive measures.

PURPOSE: Sexual quality of life (QoL) is affected during and after breast cancer (BC) treatment. The purpose was to investigate sexual and global QoL and patient-reported measures to address this issue in young women (< 51 years) with BC after the acute treatment phase, during adjuvant endocrine therapy. METHODS: Three EORTC questionnaires and an additional specific questionnaire, developed for the study, were used to assess sexual and global QoL and patient-reported supportive measures in BC patients who had received their endocrine therapy for at least 24 months. Among the 54 eligible patients, 45 (83%) agreed to participate in the study. RESULTS: We showed a deterioration in sexual QoL and poor communication with healthcare professionals. Most patients (88.9%) declared that it was important that sexuality should be discussed with caregivers and that the partner should also be involved. Most patients (60%) had taken at least one action to overcome their sexual problems. Most of these interventions (63%) originated from the patient herself. CONCLUSIONS: Sexual QoL is a major issue in young BC patients and is poorly addressed by healthcare professionals. Most of the supportive methods used by the patients to overcome these side effects were on their own initiative. Communication and counseling on sexuality by healthcare professionals need to be improved during BC treatment. Patients suggested supportive measures they would find useful and appropriate to develop in the clinic. The final goal is to improve the sexual QoL of BC patients with the appropriate intervention and support.

Text Mining in Electronic Medical Records Enables Quick and Efficient Identification of Pregnancy Cases Occurring After Breast Cancer.

PURPOSE: To apply text mining (TM) technology on electronic medical records (EMRs) of patients with breast cancer (BC) to retrieve the occurrence of a pregnancy after BC diagnosis and compare its performance to manual curation. MATERIALS AND METHODS: The training cohort (Cohort A) comprised 344 patients with BC age ≤ 40 years old treated at Institut Curie between 2005 and 2007. Manual curation consisted in manually reviewing each EMR to retrieve pregnancies. TM consisted of first applying a keyword filter ("accouch*" or "enceinte," French terms for "deliver*" and "pregnant," respectively) to select a subset of EMRs, and, second, checking manually EMRs to confirm the pregnancy. Then, we applied our TM algorithm on an independent cohort of patients with BC treated between 2008 and 2012 (Cohort B). RESULTS: In Cohort A, 36 pregnancies were identified among 344 patients (10.5%; 2,829 person-years of EMR). Thirty were identified by manual review versus 35 by TM. TM resulted in a lower percentage of manual checking (26.7% v 100%, respectively) and substantial time gains (time to identify a pregnancy: 13 minutes for TM v 244 minutes for manual curation, respectively). Presence of any of the two TM filters showed excellent sensitivity (97%) and negative predictive value (100%). In Cohort B, 67 pregnancies were identified among 1,226 patients (5.5%; 7,349 person-years of EMR). Similarly, for Cohort B, TM spared 904 (73.7%) EMRs from manual review and quickly generated a cohort of 67 pregnancies after BC. Incidence rate of pregnancy after BC was 0.01 pregnancy per person-year of EMR in both cohorts. CONCLUSION: TM is highly efficient to quickly identify rare events and is a promising tool to improve rapidity, efficiency, and costs of medical research.

Unraveling the physiological functions of exosome secretion by tumors.

To understand the physiological functions of exosomes, we have recently used the inhibition of Rab27a, which prevents exosome release but also alters other secretion pathways. Our work demonstrates that the secretion of exosomes by some tumors in vivo can influence the immune microenvironment to promote tumor progression, but also that this phenomenon cannot be generalized to all tumors and all exosomes.

Exosomes and communication between tumours and the immune system: are all exosomes equal?

Communication between cells is particularly important during tumour progression. Communication can take place through direct cell-cell interactions, but also through extracellular secretion of mediators acting at a distance. These mediators can be either soluble molecules or more complex structures called membrane vesicles, enclosing soluble factors within a lipid bilayer. A variety of extracellular membrane vesicles have been described, for instance microvesicles, ectosomes and a subtype called exosomes. The role of exosomes in tumour progression has been studied extensively in the last 10 years. In the present mini-review, we discuss our recent results, first showing the heterogeneity of the vesicles called exosomes and the probable existence of subpopulations of these exosomes, and secondly demonstrating that in vivo secretion of exosomes by some tumours can promote tumour progression, but that such a function cannot be generalized to all tumours and all exosomes.

Rab27a supports exosome-dependent and -independent mechanisms that modify the tumor microenvironment and can promote tumor progression.

During progression from single cancer cells to a tumor mass and metastases, tumor cells send signals that can subvert their tissue microenvironment. These signals involve soluble molecules and various extracellular vesicles, including a particular type termed exosomes. The specific roles of exosomes secreted in the tumor microenvironment, however, is unclear. The small GTPases RAB27A and RAB27B regulate exocytosis of multivesicular endosomes, which lead to exosome secretion, in human HeLa cells. Here, we used mouse models to show that Rab27a blockade in mammary carcinoma cells decreased secretion of exosomes characterized by endocytic markers, but also of matrix metalloproteinase 9, which is not associated with exosomes. Rab27a blockade resulted in decreased primary tumor growth and lung dissemination of a metastatic carcinoma (4T1), but not of a nonmetastatic carcinoma (TS/A). Local growth of 4T1 tumors required mobilization of a population of neutrophil immune cells induced by Rab27a-dependent secretion of exosomes together with a specific combination of cytokines and/or metalloproteinases. Our findings offer in vivo validation of the concept that exosome secretion can exert key pathophysiologic roles during tumor formation and progression, but they also highlight the idiosyncratic character of the tumor context.

Diverse subpopulations of vesicles secreted by different intracellular mechanisms are present in exosome preparations obtained by differential ultracentrifugation.

Exosomes are extracellular vesicles of 50 to 100 nm in diameter, released by many cell types. Exosomes are formed inside the cell in intracellular endosomal compartments and are secreted upon fusion of these compartments with the plasma membrane. Cells also secrete other types of membrane vesicles, for instance, by outward budding from the plasma membrane, and although some of them clearly differ from exosomes by their structural features (larger size), others are possibly more difficult to separate. Here, using Rab27a inhibition to modulate exosome secretion, we show the existence of at least 2 distinct populations of vesicles after purification by classical ultracentrifugation from mouse tumor cell conditioned medium. Rab27a inhibition lead to decreased vesicular secretion of some conventional markers of exosomes (CD63, Tsg101, Alix and Hsc70) but did not affect secretion of others (CD9 and Mfge8). By electron microscopy, CD9 was observed on vesicles of various sizes, ranging from 30 nm to more than 150 nm in diameter. Flotation onto sucrose gradients showed different proportions of CD63, CD9 and Mfge8 not only in fractions of densities classically described for exosomes (around 1.15 g/ml) but also in fractions of densities over 1.20 g/ml, indicating the presence of heterogenous vesicle populations. CD9 and Mfge8 were also found in large vesicles pelleted at low speed and can thus not be considered as specific components of endosome-derived vesicles. We propose that the most commonly used protocols for exosome preparations co-purify vesicles from endosomal and other origins, possibly the plasma membrane. Future work will be required to improve techniques for accurate purification and characterization of the different populations of extracellular vesicles.

Exosome secretion: molecular mechanisms and roles in immune responses.

Exosomes are small membrane vesicles, secreted by most cell types from multivesicular endosomes, and thought to play important roles in intercellular communications. Initially described in 1983, as specifically secreted by reticulocytes, exosomes became of interest for immunologists in 1996, when they were proposed to play a role in antigen presentation. More recently, the finding that exosomes carry genetic materials, mRNA and miRNA, has been a major breakthrough in the field, unveiling their capacity to vehicle genetic messages. It is now clear that not only immune cells but probably all cell types are able to secrete exosomes: their range of possible functions expands well beyond immunology to neurobiology, stem cell and tumor biology, and their use in clinical applications as biomarkers or as therapeutic tools is an extensive area of research. Despite intensive efforts to understand their functions, two issues remain to be solved in the future: (i) what are the physiological function(s) of exosomes in vivo and (ii) what are the relative contributions of exosomes and of other secreted membrane vesicles in these proposed functions? Here, we will focus on the current ideas on exosomes and immune responses, but also on their mechanisms of secretion and the use of this knowledge to elucidate the latter issue.

Targeting tumor antigens to secreted membrane vesicles in vivo induces efficient antitumor immune responses.

Expression of non-self antigens by tumors can induce activation of T cells in vivo, although this activation can lead to either immunity or tolerance. CD8+ T-cell activation can be direct (if the tumor expresses MHC class I molecules) or indirect (after the capture and cross-presentation of tumor antigens by dendritic cells). The modes of tumor antigen capture by dendritic cells in vivo remain unclear. Here we examine the immunogenicity of the same model antigen secreted by live tumors either in association with membrane vesicles (exosomes) or as a soluble protein. We have artificially addressed the antigen to secreted vesicles by coupling it to the factor VIII-like C1C2 domain of milk fat globule epidermal growth factor-factor VIII (MFG-E8)/lactadherin. We show that murine fibrosarcoma tumor cells that secrete vesicle-bound antigen grow slower than tumors that secrete soluble antigen in immunocompetent, but not in immunodeficient, host mice. This growth difference is due to the induction of a more potent antigen-specific antitumor immune response in vivo by the vesicle-bound than by the soluble antigen. Finally, in vivo secretion of the vesicle-bound antigen either by tumors or by vaccination with naked DNA protects against soluble antigen-secreting tumors. We conclude that the mode of secretion can determine the immunogenicity of tumor antigens and that manipulation of the mode of antigen secretion may be used to optimize antitumor vaccination protocols.