EMP2 Serves as a Functional Biomarker for Chemotherapy-Resistant Triple-Negative Breast Cancer.

Breast cancer (BC) remains among the most commonly diagnosed cancers in women worldwide. Triple-negative BC (TNBC) is a subset of BC characterized by aggressive behavior, a high risk of distant recurrence, and poor overall survival rates. Chemotherapy is the backbone for treatment in patients with TNBC, but outcomes remain poor compared to other BC subtypes, in part due to the lack of recognized functional targets. In this study, the expression of the tetraspan protein epithelial membrane protein 2 (EMP2) was explored as a predictor of TNBC response to standard chemotherapy. We demonstrate that EMP2 functions as a prognostic biomarker for patients treated with taxane-based chemotherapy, with high expression at both transcriptomic and protein levels following treatment correlating with poor overall survival. Moreover, we show that targeting EMP2 in combination with docetaxel reduces tumor load in syngeneic and xenograft models of TNBC. These results provide support for the prognostic and therapeutic potential of this tetraspan protein, suggesting that anti-EMP2 therapy may be beneficial for the treatment of select chemotherapy-resistant TNBC tumors.

89Zr-ImmunoPET for the Specific Detection of EMP2-Positive Tumors.

Epithelial membrane protein-2 (EMP2) is upregulated in a number of tumors and therefore remains a promising target for mAb-based therapy. In the current study, image-guided therapy for an anti-EMP2 mAb was evaluated by PET in both syngeneic and immunodeficient cancer models expressing different levels of EMP2 to enable a better understanding of its tumor uptake and off target accumulation and clearance. The therapeutic efficacy of the anti-EMP2 mAb was initially evaluated in high- and low-expressing tumors, and the mAb reduced tumor load for the high EMP2-expressing 4T1 and HEC-1-A tumors. To create an imaging agent, the anti-EMP2 mAb was conjugated to p-SCN-Bn-deferoxamine (DFO) and radiolabeled with 89Zr. Tumor targeting and tissue biodistribution were evaluated in syngeneic tumor models (4T1, CT26, and Panc02) and human tumor xenograft models (Ramos, HEC-1-A, and U87MG/EMP2). PET imaging revealed radioactive accumulation in EMP2-positive tumors within 24 hours after injection, and the signal was retained for 5 days. High specific uptake was observed in tumors with high EMP2 expression (4T1, CT26, HEC-1-A, and U87MG/EMP2), with less accumulation in tumors with low EMP2 expression (Panc02 and Ramos). Biodistribution at 5 days after injection revealed that the tumor uptake ranged from 2 to approximately 16%ID/cc. The results show that anti-EMP2 mAbs exhibit EMP2-dependent tumor uptake with low off-target accumulation in preclinical cancer models. The development of improved anti-EMP2 Ab fragments may be useful to track EMP2-positive tumors for subsequent therapeutic interventions.

Satisfaction of Women Faculty in Academic Medicine.

Purpose: Research about academic medicine women faculty has focused on comparisons of men and women or specific groups who achieved leadership. To better understand the low percentages of women in academic medicine leadership, attention should be paid to the career continuum within genders. Study findings will inform policies and programs to support women in building careers and acquiring leadership positions. Materials and Methods: Association of American Medical Colleges (AAMC) StandPoint Faculty Engagement Survey data are used to describe and compare women assistant, associate and full professors' perceptions of (1) career development and advancement opportunities, and (2) a culture and climate that fosters diversity, equity, and inclusion. Specific similarities and differences with men are highlighted. Results: Fifty-nine percent of women respondents were assistant, 25% associate, and 16% full professors. Associate professors of both genders were the least satisfied on the main measures. Women were less satisfied than men at each career stage across the majority of variables. Among women, fewer than half of full and associate professors, and 52% of assistant professors believe they can express their opinions without fear of retribution. While the majority at all ranks (69%-75%) report feeling respected in the workplace, among those who did not, the highest percentage of disrespect based on gender was among associate professors. Conclusions: The perceptions of >7,500 academic medicine women faculty, representing different generations and ranks, underscore the need to broadly address gender inequity and sexism throughout the career continuum. It identifies the mid-career stage as a challenging experience for both men and women. Women, especially at the associate professor rank, remain a critically dissatisfied and underresourced group that is at risk for underutilization and potentially exit from academic medicine. All ranks of women need career development and equitable policies to support their sense of belonging and career advancement.

Epithelial membrane protein 2 (EMP2) regulates hypoxia-induced angiogenesis in the adult retinal pigment epithelial cell lines.

Pathologic retinal neovascularization is a potentially blinding consequence seen in many common diseases including diabetic retinopathy, retinopathy of prematurity, and retinal vaso-occlusive diseases. This study investigates epithelial membrane protein 2 (EMP2) and its role as a possible modulator of angiogenesis in human retinal pigment epithelium (RPE) under hypoxic conditions. To study its effects, the RPE cell line ARPE-19 was genetically modified to either overexpress EMP2 or knock down its levels, and RNA sequencing and western blot analysis was performed to confirm the changes in expression at the RNA and protein level, respectively. Protein expression was evaluated under both normoxic conditions or hypoxic stress. Capillary tube formation assays with human umbilical vein endothelial cells (HUVEC) were used to evaluate functional responses. EMP2 expression was found to positively correlate with expression of pro-angiogenic factors HIF1α and VEGF at both mRNA and protein levels under hypoxic conditions. Mechanistically, EMP2 stabilized HIF1α expression through downregulation of von Hippel Lindau protein (pVHL). EMP2 mediated changes in ARPE-19 cells were also found to alter the secretion of a paracrine factor(s) in conditioned media that can regulate HUVEC migration and capillary tube formation in in vitro functional angiogenesis assays. This study identifies EMP2 as a potential mediator of angiogenesis in a human RPE cell line. EMP2 levels positively correlate with pro-angiogenic mediators HIF1α and VEGF, and mechanistically, EMP2 regulates HIF1α through downregulation of pVHL. This study supports further investigation of EMP2 as a promising novel target for therapeutic treatment of pathologic neovascularization in the retina.

Enhancing Diversity in the Ophthalmology Workforce.

Health care teams are most effective at addressing complex problems and improving health outcomes for underserved populations when team members bring diverse life experiences and perspectives to the effort. With rates of visual impairment expected to increase in the United States by 2050, especially among minority populations, diversification of the ophthalmology workforce will be critical in reducing disparities in access to and quality of vision health care. Currently, ophthalmology is less diverse with respect to race, ethnicity, and gender than graduating medical classes and other medical specialties, as well as the general US population. In addition, data on diversity in sexual orientation and gender identity, socioeconomic status, and disability are lacking in ophthalmology. The Minority Ophthalmology Mentoring and Rabb-Venable Excellence in Ophthalmology Programs are examples of initiatives to increase racial and ethnic diversity in the workforce and can serve as models for increasing other aspects of inclusiveness. Other strategies for improving vision health care for all Americans include continuing to support existing diversity programs and creating new ones; addressing unconscious and implicit bias in medical school, residency, and faculty selections; conducting holistic reviews of medical school and residency applications; diversifying selection committees and leadership; and encouraging faculty development of underrepresented groups.

Visibility & support for first generation college graduates in medicine.

Of Being a First Generation (First Gen) college graduate is an important intersectionality which impacts the lens through which First Gen students learn to become physicians. In this Perspective, we define the First Gen identity and review some of the salient First Gen literature as it applies to the medical school experience. We discuss the conception, design and execution of First Gen initiatives and program development at our medical school as a call to action and model for other institutions to create communities for their First Gen populations, focusing on inclusion and tailored support. We describe the framework through which we envisioned our programming for First Gen medical students, trainees, staff, and faculty at the David Geffen School of Medicine at UCLA.

An Eye on Gender Equality: A Review of the Evolving Role and Representation of Women in Ophthalmology.

PURPOSE: In recent decades, women have achieved greater representation in ophthalmology. Globally, women now constitute approximately 25%-30% of ophthalmologists and 35%-45% of trainees. Nevertheless, women remain under-represented in key areas, including positions of professional and academic leadership and ophthalmic surgical subspecialization. Furthermore, there is evidence that women in ophthalmology encounter more bias and discrimination across multiple domains than men, including a gender-pay gap that is wider than in many other surgical subspecialties. Women ophthalmologists and trainees report sharply differing training experiences from male peers, including fewer opportunities to operate, more bullying and harassment, less access to mentorship, and contrasting expectations around contributions to family life. DESIGN: Perspective. METHODS: An extensive literature search was undertaken to compile and review papers published with a focus on gender equity across ophthalmology, surgery, and medicine. RESULTS: We identified 8 broad domains that were widely discussed: leadership, research and academics, income, surgical exposure and subspecialization, harassment, career satisfaction, mentorship, and family and marital differences. We have summarized the current research across each of these areas, and discussed possible solutions to reduce the inequities reported. CONCLUSIONS: This review draws on current research published around representation and experiences of women in ophthalmology and suggests that there are opportunities to improve gender inequity.

Clinical Utility of Antiretinal Antibody Testing.

IMPORTANCE: The clinical utility of most antiretinal antibodies (retina antibodies) currently available for testing remains unclear and unproven. Despite this, the presence of retinal antibodies is included in current diagnostic autoimmune retinopathy criteria. OBJECTIVE: To evaluate the clinical significance of comprehensive retinal antibody evaluations currently offered in North America. DESIGN, SETTING, AND PARTICIPANTS: In this cross-sectional study, 14 patients without autoimmune retinopathy were recruited into the Mayo Clinic Neuroimmunology Biorepository for this study between January 1, 2019, and October 1, 2019. These serum samples without autoimmune retinopathy were sent in masked fashion to a Clinical Laboratory Improvement Amendments-certified laboratory. Using similar methods, the Mayo Clinic Neuroimmunology Research Laboratory independently assessed the same sample to ascertain reproducibility of the findings. MAIN OUTCOMES AND MEASURES: Results of the autoimmune retinopathy and cancer-associated retinopathy panels. RESULTS: Thirteen of 14 (93%; 95% CI, 66%-100%) serum samples tested positive for retinal antibodies, with a median of 5 retinal antibodies (range, 0-8) per patient at the Clinical Laboratory Improvement Amendments-certified laboratory, which provides a specificity of 7% (95% CI, 0%-34%). Confirmatory immunohistochemistry staining in human retina was present in 12 of 14 samples (86%). α-Enolase was found in 9 (64%). The only retinal antibody not present was recoverin. These nonspecific retinal antibody results were replicated at the Mayo Clinic Laboratory on Western blot using pig retina proteins as substrate. CONCLUSIONS AND RELEVANCE: The presence of retinal antibodies in 93% of the patients without autoimmune retinopathy indicates a lack of specificity and that most detectable retinal antibodies have limited clinical relevance in the evaluation of patients for suspected autoimmune retinopathy. Current retinal antibody testing, other than recoverin, should be interpreted with caution, especially for cases of low clinical suspicion. The poor specificity is important to recognize to prevent the potentially unnecessary commencement of systemic immunosuppressants that may result in significant extraocular adverse effects. Identification of biomarkers that have a high predictive value for inflammatory or autoimmune retinal diseases is needed to move the field forward.

Three-dimensional Imaging Coupled with Topological Quantification Uncovers Retinal Vascular Plexuses Undergoing Obliteration.

Introduction: Murine models provide microvascular insights into the 3-D network disarray seen in retinopathy and cardiovascular diseases. Light-sheet fluorescence microscopy (LSFM) has emerged to capture retinal vasculature in 3-D, allowing for assessment of the progression of retinopathy and the potential to screen new therapeutic targets in mice. We hereby coupled LSFM, also known as selective plane illumination microscopy, with topological quantification, to characterize the retinal vascular plexuses undergoing preferential obliteration. Method and Result: In postnatal mice, we revealed the 3-D retinal microvascular network in which the vertical sprouts bridge the primary (inner) and secondary (outer) plexuses, whereas, in an oxygen-induced retinopathy (OIR) mouse model, we demonstrated preferential obliteration of the secondary plexus and bridging vessels with a relatively unscathed primary plexus. Using clustering coefficients and Euler numbers, we computed the local versus global vascular connectivity. While local connectivity was preserved (p > 0.05, n = 5 vs. normoxia), the global vascular connectivity in hyperoxia-exposed retinas was significantly reduced (p < 0.05, n = 5 vs. normoxia). Applying principal component analysis (PCA) for auto-segmentation of the vertical sprouts, we corroborated the obliteration of the vertical sprouts bridging the secondary plexuses, as evidenced by impaired vascular branching and connectivity, and reduction in vessel volumes and lengths (p < 0.05, n = 5 vs. normoxia). Conclusion: Coupling 3-D LSFM with topological quantification uncovered the retinal vasculature undergoing hyperoxia-induced obliteration from the secondary (outer) plexus to the vertical sprouts. The use of clustering coefficients, Euler's number, and PCA provided new network insights into OIR-associated vascular obliteration, with translational significance for investigating therapeutic interventions to prevent visual impairment.

Population-Based Frequency of Ophthalmic Adverse Events in Melanoma, Other Cancers, and After Immune Checkpoint Inhibitor Treatment.

PURPOSE: To examine the frequency of ophthalmic immune-related adverse events (OirAEs) in melanoma, other cancers, and after immune checkpoint inhibitor (ICI) treatment. DESIGN: Retrospective clinical cohort study. METHODS: This study identified patients diagnosed with OirAEs between January 1, 2011, and December 31, 2018, in the Kaiser Permanente Southern California electronic health records. The primary exposures of interest were prior initiation of ICIs and underlying cancer diagnosis. Risk-adjusted prevalence of OirAEs was evaluated in patients with melanoma, with nonmelanoma cancer, and without cancer. The 1-year incidence of OirAEs and recurrence of prior ophthalmic disease were identified in ICI-receiving patients with melanoma and nonmelanoma. RESULTS: Among 4,695,669 unique patients identified, 9.9% had a cancer diagnosis, of whom 2.8% had a diagnosis of melanoma. Overall prevalence for uveitis and selected neuro-ophthalmic diagnoses was 341.8/100,000 patient-years in patients with melanoma and 369.6/100,000 patient-years in patients with nonmelanoma cancer regardless of ICI treatment, compared with 142.2/100,000 patient-years in patients without cancer. A total of 2,911 unique patients received ICI therapy. Compared with patients with nonmelanoma cancer, patients with melanoma on any ICI had elevated 1-year incidence rates of uveitis (1.2% vs 0.2%; risk-adjusted odds ratio, 6.45). High 1-year recurrence rates for uveitis in ICI patients with a prior uveitis history were also observed. CONCLUSIONS: The prevalence of all OirAEs was substantially higher in patients with cancer, with ICI-related uveitis risk specifically increased in patients with melanoma compared with patients with nonmelanoma cancer. Evidence-based guidelines for ophthalmic monitoring of patients undergoing ICI treatment may require different risk stratifications based on underlying cancer diagnosis, specific ICI used, and prior history of uveitis.

Bullying, harassment and sexual discrimination among ophthalmologists in Australia and New Zealand.

BACKGROUND: Discrimination, bullying and sexual harassment (DBSH) impact the psychological well-being of doctors and contribute to poor health outcomes. The Royal Australian and New Zealand College of Ophthalmologists (RANZCO) commissioned independent surveys to evaluate DBSH among members/trainees. METHODS: Anonymous online surveys by Best Practice Australia were undertaken in 2015 and 2018. Cross-sectional analysis was prevalence of perceived DBSH, rates of reporting, intervention and resolution undertaken. Response rate was 50% (658/1319) in 2015 and 40% (557/1401) in 2018. In both surveys, 29% were female. This is representative of the distribution of the RANZCO members. RESULTS: In a 2015 survey, 37.6% of respondents experienced DBSH, with prevalence being the highest for females (62.3%; N = 104 cf males 27.7%; N = 167) and trainees (49.2%; N = 61). In 2018, 49.2% of respondents reported DBSH with rates low for all forms of DBSH (22%-29%). Sexual harassment was reported by 12% and the least discussed or reported. Respondents strategy for taking action included draw on personal support network (25-43%), official complaints to supervisors (16-22%), human resources (2%-10%) and RANZCO (0%-6%). Reasons for not taking action included fear of impact of future career options (54.1%-60.7%), fear of victimization (35.7%-50.4%) and afraid of not being believed (31.9%-52.4%). Satisfactory resolution rates were 6% to 25%. A majority of respondents (77%) were positive about RANZCO initiatives. CONCLUSIONS: DBSH is commonly reported by RANZCO members with female ophthalmologists more than two times more likely to experience any one of the four behaviours, three times more likely to experience discrimination and six times for sexual harassment. Fear of compromising personal and career progression contribute to low levels of reporting.

Ophthalmic Immune-Related Adverse Events after Anti-CTLA-4 or PD-1 Therapy Recorded in the American Academy of Ophthalmology Intelligent Research in Sight Registry.

PURPOSE: Detailed study of ophthalmic immune-related adverse events (AEs), including determination of incidence and recurrence rates, is of integral importance in cancer immunotherapy to inform management and treatment guidelines. DESIGN: Retrospective registry study. PARTICIPANTS: Patients newly diagnosed with ophthalmic immune-related AEs between January 1, 2013, and December 31, 2017, in the American Academy of Ophthalmology's Intelligent Research in Sight (IRIS®) Registry. METHODS: Data were collected from electronic health records of IRIS® Registry participating ophthalmology practices. Patients with select ophthalmic immune-related AEs were identified by International Classification of Diseases diagnosis codes. The primary exposure of interest was prior initiation of immune checkpoint inhibitors (ICIs). MAIN OUTCOME MEASURES: Incidence of ophthalmic immune-related AEs within 1 year after initiation of ICI therapy was determined. Incidence rate ratios (IRRs) were derived by comparing incidence of ophthalmic immune-related AEs after ICIs versus rates of the same ocular complications in patients not taking ICIs in the entire registry population. Rates of ophthalmic immune-related AEs in patients with a past history of ocular inflammation or other specific ophthalmic condition before initiation of ICIs were examined further. RESULTS: A total of 3123 patients who received anti-CTLA-4 or anti-programmed cell death 1 (PD-1) therapy were identified, 112 of whom demonstrated an ophthalmic immune-related AE. Incidence rates for anterior uveitis, the most common ophthalmic immune-related AE, were 8209 per 100 000 for ipilimumab (anti-CTLA-4), 2542 per 100 000 for nivolumab (anti-PD-1), 2451 per 100 000 for pembrolizumab (anti-PD-1), 5556 per 100 000 for ipilimumab plus nivolumab, and 3740 per 100 000 among all ICIs. Rates of ophthalmic immune-related AEs among patients receiving ICI therapy were higher compared with baseline rates in the general registry population (anterior uveitis IRR, 13.9; other uveitis IRR, 43.0; papilledema IRR, 38.3). Patients with a history of uveitis or other ocular inflammatory condition demonstrated high recurrence rates of ophthalmic immune-related AEs after initiating ICIs (up to 51.1%). CONCLUSIONS: For patients initiating ICI therapy, early coordination with ophthalmic subspecialist care is important because rates of ophthalmic immune-related AEs are elevated compared with ocular complication rates in the entire registry population and patients with a history of prior autoimmune ocular disease are at high risk of recurrence of ocular complications.

Neuro-Ophthalmic Complications in Patients Treated With CTLA-4 and PD-1/PD-L1 Checkpoint Blockade.

BACKGROUND: In recent years, CTLA-4 and PD-1/PD-L1 checkpoint inhibitors have proven to be effective and have become increasingly popular treatment options for metastatic melanoma and other cancers. These agents work by enhancing autologous antitumor immune responses. Immune-related ophthalmologic complications have been reported in association with checkpoint inhibitor use but remain incompletely characterized. This study seeks to investigate and further characterize the neuro-ophthalmic and ocular complications of immune checkpoint blockade treatment. METHODS: A survey was distributed through the secure electronic data collection tool REDCap to neuro-ophthalmology specialists in the North American Neuro-Ophthalmology Society listserv. The study received human subjects approval through the University of California at Los Angeles Institutional Review Board. The survey identified patients sent for neuro-ophthalmic consultation while receiving one or more of a PD-1 inhibitor (pembrolizumab, nivolumab, or cemiplimab); PD-L1 inhibitor (atezolizumab, avelumab, or durvalumab); or the CTLA-4 inhibitor ipilimumab. Thirty-one patients from 14 institutions were identified. Patient demographics, neuro-ophthalmic diagnosis, diagnostic testing, severity, treatment, clinical response, checkpoint inhibitor drug used, and cancer diagnosis was obtained. RESULTS: The checkpoint inhibitors used in these patients included pembrolizumab (12/31), nivolumab (6/31), combined ipilimumab with nivolumab (7/31, one of whom also received pembrolizumab during their course of treatment), durvalumab (3/31), ipilimumab (2/31), and cemiplimab (1/31). Malignant melanoma (16/31) or nonsmall cell lung carcinoma (6/31) were the most common malignancies. The median time between first drug administration and the time of ophthalmological symptom onset was 14.5 weeks. Eleven patients had involvement of the optic nerve, 7 patients had inflammatory orbital or extraocular muscle involvement, 6 patients had ocular involvement from neuromuscular junction dysfunction, 4 patients had cranial nerve palsy, and 4 patients had non neuro-ophthalmic complications. Use of systemic corticosteroids with or without stopping the checkpoint inhibitor resulted in improvement of most patients with optic neuropathy, and variable improvement for the other ophthalmic conditions. CONCLUSION: This study describes the variable neuro-ophthalmic adverse events associated with use of immune checkpoint inhibitors and contributes a more thorough understanding of their clinical presentations and treatment outcomes. We expect this will increase awareness of these drug complications and guide specialists in the care of these patients.

Increased epithelial membrane protein 2 expression in glioblastoma after treatment with bevacizumab.

BACKGROUND: Antiangiogenic therapy with bevacizumab has failed to provide substantial gains in overall survival. Epithelial membrane protein 2 (EMP2) is a cell surface protein that has been previously shown to be expressed in glioblastoma, correlate with poor survival, and regulate neoangiogenesis in cell lines. Thus, the relationship between bevacizumab and EMP2 was investigated. METHODS: Tumor samples were obtained from 12 patients with newly diagnosed glioblastoma at 2 time points: (1) during the initial surgery and (2) during a subsequent surgery following disease recurrence post-bevacizumab treatment. Clinical characteristics and survival data from these patients were collected, and tumor samples were stained for EMP2 expression. The IVY Glioblastoma Atlas Project database was used to evaluate EMP2 expression levels in 270 samples by differing histological areas of the tumor. RESULTS: Patients with high EMP2 staining at initial diagnosis had decreased progression-free and overall survival after bevacizumab (median progression-free survival 4.6 months vs 5.9 months; log-rank P = .076 and overall survival 7.7 months vs 14.4 months; log-rank P = .011). There was increased EMP2 staining in samples obtained after bevacizumab treatment in both unpaired (mean H-score 2.31 vs 1.76; P = .006) and paired analyses (mean difference 0.571; P = .019). This expression increase correlated with length of bevacizumab therapy (R 2  = 0.449; Pearson P = .024). CONCLUSIONS: Bevacizumab treatment increased EMP2 protein expression. This increase in EMP2 correlated with reduced mean survival time post-bevacizumab therapy. We hypothesize a role of EMP2 in clinical bevacizumab resistance and as a potential antiangiogenic therapeutic target in glioblastoma.

EMP2 Is a Novel Regulator of Stemness in Breast Cancer Cells.

Little is known about the role of epithelial membrane protein-2 (EMP2) in breast cancer development or progression. In this study, we tested the hypothesis that EMP2 may regulate the formation or self-renewal of breast cancer stem cells (BCSC) in the tumor microenvironment. In silico analysis of gene expression data demonstrated a correlation of EMP2 expression with known metastasis-related genes and markers of cancer stem cells (CSC) including aldehyde dehydrogenase (ALDH). In breast cancer cell lines, EMP2 overexpression increased and EMP2 knockdown decreased the proportion of stem-like cells as assessed by the expression of the CSC markers CD44+/CD24-, ALDH activity, or by tumor sphere formation. In vivo, upregulation of EMP2 promoted tumor growth, whereas knockdown reduced the ALDHhigh CSC population as well as retarded tumor growth. Mechanistically, EMP2 functionally regulated the response to hypoxia through the upregulation of HIF-1α, a transcription factor previously shown to regulate the self-renewal of ALDHhigh CSCs. Furthermore, in syngeneic mouse models and primary human tumor xenografts, mAbs directed against EMP2 effectively targeted CSCs, reducing the ALDH+ population and blocking their tumor-initiating capacity when implanted into secondary untreated mice. Collectively, our results show that EMP2 increases the proportion of tumor-initiating cells, providing a rationale for the continued development of EMP2-targeting agents.

Identification of epithelial membrane protein 2 (EMP2) as a molecular marker and correlate for angiogenesis in meningioma.

PURPOSE: Although intracranial meningiomas are the most common primary brain tumor in adults, treatment options are few and have traditionally been limited to surgical resection and radiotherapy. Additional targeted therapies and biomarkers are needed, especially as complete surgical resection is frequently not feasible in many patients. METHODS: Non-pathologic brain tissue from 3 patients undergoing routine autopsies and tumor specimens from 16 patients requiring surgical resection for meningioma were collected. EMP2 protein expression was evaluated by immunohistochemistry and western blot analysis. EMP2 mRNA expression was also investigated using surgical specimens and validated by analysis of several independent NCBI GEO databases. RESULTS: EMP2 mRNA expression levels were found to be higher in meningioma relative to non-pathologic meninges (P = 0.0013) and brain (P = 0.0011). Concordantly, strong EMP2 protein expression was demonstrated in 100% of meningioma specimens from all 16 patients, with no observable protein expression in normal brain tissue samples from 3 subjects (P < 0.001). EMP2 expression was confirmed by western blot analysis in five samples, with EMP2 protein intensity positively correlating with histologic staining score (R2 = 0.780; P = 0.047). No association was found between EMP2 mRNA or protein levels and WHO grade or markers of proliferation. However, EMP2 expression was positively associated with an angiomatous pattern on histologic evaluation (P = 0.0597), VEGF-A mRNA expression (P < 0.001), and clinical markers of tumor vascularity such as operative blood loss (P = 0.037). CONCLUSIONS: EMP2 is not found in normal brain tissue, yet has shown consistently high mRNA and protein expression in meningiomas, and may serve as a useful molecular marker for these tumors.