Histopathological correlation of brain tumor recurrence vs. radiation effect post-radiosurgery as detected by MRI contrast clearance analysis: a validation study.

PURPOSE: The differentiation between adverse radiation effects (ARE) and tumor recurrence or progression (TRP) is a major decision-making point in the follow-up of patients with brain tumors. The advent of immunotherapy, targeted therapy and radiosurgery has made this distinction difficult to achieve in several clinical situations. Contrast clearance analysis (CCA) is a useful technique that can inform clinical decisions but has so far only been histologically validated in the context of high-grade gliomas. METHODS: This is a series of 7 patients, treated between 2018 and 2023, for various brain pathologies including brain metastasis, atypical meningioma, and high-grade glioma. MRI with contrast clearance analysis was used to inform clinical decisions and patients underwent surgical resection as indicated. The histopathology findings were compared with the CCA findings in all cases. RESULTS: All seven patients had been treated with gamma knife radiosurgery and were followed up with periodic MR imaging. All patients underwent CCA when the necessity to distinguish tumor recurrence from radiation necrosis arose, and subsequently underwent surgery as indicated. Concordance of CCA findings with histological findings was found in all cases (100%). CONCLUSIONS: Based on prior studies on GBM and the surgical findings in our series, delayed contrast extravasation MRI findings correlate well with histopathology across a wide spectrum of brain tumor pathologies. CCA can provide a quick diagnosis and have a direct impact on patients' treatment and outcomes.

Survivin in lung cancer: a potential target for therapy and prevention-a narrative review.

Background and Objective: A versatile biomarker, survivin, is highly expressed in proliferating cells of multiple cancers in humans and animals. It is an apoptosis-regulating protein, engaging in a cascade of reactions that involve several other genes and protein interactions. Currently, researchers are investigating its therapeutic potential due to the evidence linking its overexpression to advanced-stage lung cancer. This review is centered around examining survivin-related molecular mechanisms and its therapeutic role specifically in lung cancer. Our objective is to discuss the role of survivin in prognosis and treatment response, shedding light on immune-targeted therapies, as well as outlining future directions for survivin-based vaccines in lung cancer. Methods: The PubMed database and the United States National Library of Medicine search engine at the National Institutes of Health were searched on 24 August 2023 to identify published research studies. Searching "((((((airway [Title/Abstract]) OR (lung [Title/Abstract])) OR (pulm[Title/Abstract])) OR (bronch[Title/Abstract])) OR (nslc[Title/Abstract])) AND (((cancer[Title/Abstract]) OR (carcino[Title/Abstract])) OR (oncol[Title/Abstract]))) AND (survivin[Title/Abstract])" gave 728 results. After screening the title and abstracts and excluding the review articles 168 titles were shortlisted and full text studied. The discussions are added to relevant sections. Key Content and Findings: Survivin is a cell cycle-dependent, inhibitor of apoptosis protein that contributes to carcinogenesis, tumor vascularization, metastasis, and treatment resistance. Several treatments that impact survivin either directly or indirectly have been reported as effective in treating lung cancer. Immunity-based therapy, a novel approach known for its targeted nature and minimal side effects, is currently under investigation for lung cancer treatment. Emerging survivin-centered vaccines exhibit promising attributes in terms of safety, effectiveness, and ability to stimulate an immune response. These factors point towards a significant potential for advancing the future of lung cancer prevention and enhancing overall survival rates. Conclusions: Nuclear survivin is a potential biomarker for advanced non-small cell lung cancer. It plays a role in determining drug responsiveness and is found to be significantly elevated in cases of resistance to chemotherapy. Multiple compounds and immunization strategies have been identified to impact lung cancer cells; however, they are currently in the early stages of phase I or phase II clinical trials. The substantial promise of survivin-based immunogenicity-focused treatments warrants in-depth investigation and exploration.

Bevacizumab and gamma knife radiosurgery for first-recurrence glioblastoma.

INTRODUCTION: Glioblastoma (GBM) is the most common central nervous system malignancy in adults. Despite decades of developments in surgical management, radiation treatment, chemotherapy, and tumor treating field therapy, GBM remains an ultimately fatal disease. There is currently no definitive standard of care for patients with recurrent glioblastoma (rGBM) following failure of initial management. OBJECTIVE: In this retrospective cohort study, we set out to examine the relative effects of bevacizumab and Gamma Knife radiosurgery on progression-free survival (PFS) and overall survival (OS) in patients with GBM at first-recurrence. METHODS: We conducted a retrospective review of all patients with rGBM who underwent treatment with bevacizumab and/or Gamma Knife radiosurgery at Roswell Park Comprehensive Cancer Center between 2012 and 2022. Mean PFS and OS were determined for each of our three treatment groups: Bevacizumab Only, Bevacizumab Plus Gamma Knife, and Gamma Knife Only. RESULTS: Patients in the combined treatment group demonstrated longer post-recurrence median PFS (7.7 months) and median OS (11.5 months) compared to glioblastoma patients previously reported in the literature, and showed improvements in total PFS (p=0.015), total OS (p=0.0050), post-recurrence PFS (p=0.018), and post-recurrence OS (p=0.0082) compared to patients who received either bevacizumab or Gamma Knife as monotherapy. CONCLUSION: This study demonstrates that the combined use of bevacizumab with concurrent stereotactic radiosurgery can have improve survival in patients with rGBM.

Functional Contribution and Clinical Implication of Cancer-Associated Fibroblasts in Glioblastoma.

PURPOSE: The abundance and biological contribution of cancer-associated fibroblasts (CAF) in glioblastoma (GBM) are poorly understood. Here, we aim to uncover its molecular signature, cellular roles, and potential tumorigenesis implications. EXPERIMENTAL DESIGN: We first applied single-cell RNA sequencing (RNA-seq) and bioinformatics analysis to identify and characterize stromal cells with CAF transcriptomic features in human GBM tumors. Then, we performed functional enrichment analysis and in vitro assays to investigate their interactions with malignant GBM cells. RESULTS: We found that CAF abundance was low but significantly correlated with tumor grade, poor clinical outcome, and activation of extracellular matrix remodeling using three large cohorts containing bulk RNA-seq data and clinical information. Proteomic analysis of a GBM-derived CAF line and its secretome revealed fibronectin (FN1) as a critical candidate factor mediating CAF functions. This was validated using in vitro cellular models, which demonstrated that CAF-conditioned media and recombinant FN1 could facilitate the migration and invasion of GBM cells. In addition, we showed that CAFs were more abundant in the mesenchymal-like state (or subtype) than in other states of GBMs. Interestingly, cell lines resembling the proneural state responded to the CAF signaling better for the migratory and invasive phenotypes. CONCLUSIONS: Overall, this study characterized the molecular features and functional impacts of CAFs in GBM, alluding to novel cell interactions mediated by CAFs in the GBM microenvironment.

Phase IIa Study of SurVaxM Plus Adjuvant Temozolomide for Newly Diagnosed Glioblastoma.

PURPOSE: Despite intensive treatment with surgery, radiation therapy, temozolomide (TMZ) chemotherapy, and tumor-treating fields, mortality of newly diagnosed glioblastoma (nGBM) remains very high. SurVaxM is a peptide vaccine conjugate that has been shown to activate the immune system against its target molecule survivin, which is highly expressed by glioblastoma cells. We conducted a phase IIa, open-label, multicenter trial evaluating the safety, immunologic effects, and survival of patients with nGBM receiving SurVaxM plus adjuvant TMZ following surgery and chemoradiation (ClinicalTrials.gov identifier: NCT02455557). METHODS: Sixty-four patients with resected nGBM were enrolled including 38 men and 26 women, in the age range of 20-82 years. Following craniotomy and fractionated radiation therapy with concurrent TMZ, patients received four doses of SurVaxM (500 µg once every 2 weeks) in Montanide ISA-51 plus sargramostim (granulocyte macrophage colony-stimulating factor) subcutaneously. Patients subsequently received adjuvant TMZ and maintenance SurVaxM concurrently until progression. Progression-free survival (PFS) and overall survival (OS) were reported. Immunologic responses to SurVaxM were assessed. RESULTS: SurVaxM plus TMZ was well tolerated with no serious adverse events attributable to SurVaxM. Of the 63 patients who were evaluable for outcome, 60 (95.2%) remained progression-free 6 months after diagnosis (prespecified primary end point). Median PFS was 11.4 months and median OS was 25.9 months measured from first dose of SurVaxM. SurVaxM produced survivin-specific CD8+ T cells and antibody/immunoglobulin G titers. Apparent clinical benefit of SurVaxM was observed in both methylated and unmethylated patients. CONCLUSION: SurVaxM appeared to be safe and well tolerated. The combination represents a promising therapy for nGBM. For patients with nGBM treated in this manner, PFS may be an acceptable surrogate for OS. A large randomized clinical trial of SurVaxM for nGBM is in progress.

Meta-analysis of overall survival and postoperative neurologic deficits after resection or biopsy of butterfly glioblastoma.

Butterfly glioblastoma (bGBM) is a grade 4 glioma with a poor prognosis. Surgical treatment of these cancers has been reviewed in the literature with some recent studies supporting resection as a safe and effective treatment instead of biopsy and adjuvant therapy. This meta-analysis was designed to determine whether there are significant differences in overall survival (OS) and postoperative neurologic deficits (motor, speech, and cranial nerve) following intervention in patients who underwent tumor resection as part of their treatment, compared to patients who underwent biopsy without surgical resection. A literature search was conducted using PubMed (National Library of Medicine) and Embase (Elsevier) to identify articles from each database's earliest records to May 25, 2021, that directly compared the outcomes of biopsy and resection in bGBM patients and met predetermined inclusion criteria. A meta-analysis was conducted to compare the effects of the two management strategies on OS and postoperative neurologic deficits. Six articles met our study inclusion criteria. OS was found to be significantly longer for the resection group at 6 months (odds ratio [OR] 2.94, 95% confidence interval [CI] 1.23-7.05) and 12 months (OR 3.75, 95% CI 1.10-12.76) than for the biopsy group. No statistically significant differences were found in OS at 18 and 24 months. Resection was associated with an increased rate of postoperative neurologic deficit (OR 2.05, 95% CI 1.02-4.09). Resection offers greater OS up to 1 year postintervention than biopsy alone; however, this comes at the cost of higher rates of postoperative neurologic deficits.

Wild type, dEX3 and 2B survivin isoforms localize to the tumor cell plasma membrane, are secreted in exosomes, and interact with extracellular tubulin.

The Inhibitor of Apoptosis Protein survivin (svn) is upregulated in nearly all types of cancer and represents a promising therapeutic target. Localization to specific subcellular compartments and interactions with various binding partners allow survivin to play diverse roles in apoptosis resistance and mitosis. Survivin has recently been found in two extracellular compartments: the outer plasma membrane and secreted exosomes. In addition to svn-wt, splice variants svn-dEX3 and svn-2B are also overexpressed in human tumors. Here we show that, similarly to svn-wt, svn-dEX3 and svn-2B can be displayed on the outer plasma membrane, and secreted in exosomes. Additionally, we have identified a novel interaction of all three forms of survivin with secreted tubulin.

Prospective prediction of clinical drug response in high-grade gliomas using an ex vivo 3D cell culture assay.

BACKGROUND: Clinical outcomes in high-grade glioma (HGG) have remained relatively unchanged over the last 3 decades with only modest increases in overall survival. Despite the validation of biomarkers to classify treatment response, most newly diagnosed (ND) patients receive the same treatment regimen. This study aimed to determine whether a prospective functional assay that provides a direct, live tumor cell-based drug response prediction specific for each patient could accurately predict clinical drug response prior to treatment. METHODS: A modified 3D cell culture assay was validated to establish baseline parameters including drug concentrations, timing, and reproducibility. Live tumor tissue from HGG patients were tested in the assay to establish response parameters. Clinical correlation was determined between prospective ex vivo response and clinical response in ND HGG patients enrolled in 3D-PREDICT (ClinicalTrials.gov Identifier: NCT03561207). Clinical case studies were examined for relapsed HGG patients enrolled on 3D-PREDICT, prospectively assayed for ex vivo drug response, and monitored for follow-up. RESULTS: Absent biomarker stratification, the test accurately predicted clinical response/nonresponse to temozolomide in 17/20 (85%, P = .007) ND patients within 7 days of their surgery, prior to treatment initiation. Test-predicted responders had a median overall survival post-surgery of 11.6 months compared to 5.9 months for test-predicted nonresponders (P = .0376). Case studies provided examples of the clinical utility of the assay predictions and their impact upon treatment decisions resulting in positive clinical outcomes. CONCLUSION: This study both validates the developed assay analytically and clinically and provides case studies of its implementation in clinical practice.

Lateral Temporal Approach for Image-Guided Stereotactic Biopsy of Pineal Region Tumors.

BACKGROUND: Biopsy of pineal region neoplasms is frequently accomplished by way of endoscopic transventricular access or using an image-guided, computer-assisted stereotactic approach. METHODS: We evaluated a nonorthogonal lateral temporal approach for stereotactic biopsy of pineal region tumors as a variation of previously described stereotactic methods. Magnetic resonance imaging-guided frameless stereotaxy was used to plan and perform biopsies of pineal region tumors using a nonorthogonal trajectory extending from the superior or middle temporal gyri through the temporal stem, anterior to the atrium of the lateral ventricle, and posterior to the corticospinal tract. RESULTS: All patients had an uncomplicated postoperative course and remained at neurologic baseline. No parenchymal or ventricular hemorrhage was present on postoperative scans. A tissue diagnosis was obtained in all patients. CONCLUSIONS: This method appears to be a safe alternative to stereotactic biopsy using other trajectories and provides adequate tissue for definitive diagnosis.

The Presence of Survivin on B Cells from Myasthenia Gravis Patients and the Potential of an Antibody to a Modified Survivin Peptide to Alleviate Weakness in an Animal Model.

Myasthenia gravis (MG) is an autoimmune disease in which Abs target neuromuscular junction proteins, in particular the acetylcholine receptor. We previously identified the antiapoptotic protein survivin in the autoreactive B cells and plasma cells of MG patients. To further define the role of survivin in MG, we have assessed PBMCs from 29 patients with MG and 15 controls. We confirmed the increased expression of survivin in CD20+ lymphocytes from MG patients compared with controls. Furthermore, the CD20+ population of cells from MG patients contained a higher percentage of extracellular survivin compared with controls. The analysis of CD4+ cells showed an increased percentage of intracellular survivin in MG patients compared with controls, whereas the extracellular survivin CD4+ percentage was unaffected. In an experimental mouse model of MG, we assessed the therapeutic potential of an Ab raised to a modified survivin peptide but cross-reactive to survivin. Ab treatment reduced disease severity, lowered acetylcholine receptor-specific Abs, and decreased CD19+ survivin+ splenocytes. The ability to target survivin through Ab recognition of autoreactive cells offers the potential for a highly specific therapeutic agent for MG.

Exploring the role of survivin in neuroendocrine neoplasms.

Neuroendocrine tumors (NETs) are a heterogenous group of tumors. While most NETs have excellent prognosis, certain subsets have aggressive biology and have limited treatment options. We explored the role of survivin in NET as a prognostic and potentially therapeutic marker. Tissue microarrays of 132 patients were stained for survivin using immunohistochemistry (IHC) and correlated with outcomes. Using genomic database, we then correlated survivin (BIRC5) mRNA expression with radiosensitivity index (RSI) in 52 samples of NET. Finally, we studied the effect of radiation on survivin expression in human cell lines and the impact of knock-down of BIRC5 on cell proliferation and radiation sensitivity. We found that survivin positivity by IHC correlated with a shorter survival (overall survival 8.5 years vs. 18.3 years, p < 0.001). There was a positive correlation between BIRC5 expression and RSI (r = 0.234, p < 0.0001). Radiation exposure increased BIRC5 gene expression in a human carcinoid cell line. Knockout of BIRC5 using siRNA reduced proliferation of neuroendocrine cells but did not increase radiation sensitivity. We conclude that survivin expression in NET correlates with an inferior survival and survivin expression in human carcinoid cell lines increases after exposure to ionizing radiation.

Black Bone Disease of the Skull.

We present an image of a patient's skull characterized by dark, irregular discoloration. This was discovered incidentally in a 66-year-old man who underwent craniotomy for resection of a glioblastoma. This image demonstrates cranial black bone disease. This is an abnormal bone pigmentation associated with long-term tetracycline use, as occurred in this patient.

Disparities among racial/ethnic groups of patients diagnosed with ependymoma: analyses from the Surveillance, Epidemiology and End Results (SEER) registry.

PURPOSE: The aim of this study was to identify racial/ethnic disparities with regard to survival among patients with ependymoma. METHODS: Data from the Surveillance, Epidemiology and End Results (SEER) registry between the years of 1973-2015 which included 4821 patients diagnosed with ependymoma were analyzed. Multivariable cox proportional hazard ratios were performed to examine overall survival across racial/ethnic groups of patients with ependymoma, mortality risks across specified age groups, and mortality during specified time intervals, all with corresponding 95% confidence intervals. RESULTS: Non-Hispanic black patients (n = 421) have higher risk of overall mortality when compared to non-Hispanic white patients (n = 3255) with ependymoma (HR 1.48, CI 1.17-1.87). Risk of mortality was highest when comparing non-Hispanic black children under the age of 3 to non-Hispanic white children of the same age group (HR 3.05, CI 1.55-5.99). Mortality risk has increased among pediatric non-Hispanic black patients compared to pediatric non-Hispanic white patients between the years of 2006-2015, from previous rates between the years 1973-2005 (HR 1.95, CI 1.15-3.33 and HR 2.35, CI 1.24-4.44). Hispanic patients under 3 years had an increased risk of mortality compared to non-Hispanic white patients of this age group (HR 2.49, CI 1.37-4.53). Asian/Pacific Islander patients (n = 282) had no significant difference in outcomes when compared to non-Hispanic white patients. CONCLUSIONS: Our findings showed higher risk of mortality among non-Hispanic black patients compared to non-Hispanic white patients with ependymoma, with highest risk among pediatric patients. These results demonstrate significant need for research in survival outcomes for this disease.

The case for radiosurgery for brainstem metastases.

PURPOSE: To challenge the prevalent pessimism regarding the outcome of patients with metastases in the brainstem resulting in the use of whole brain radiation for palliation rather than stereotactic radiosurgery for definitive control and preservation of quality of life. We present our single institution review of the efficacy and safety of treating brainstem metastases aggressively with GKRS. METHODS: Forty-one patients with 45 total lesions treated with GKRS were included. Mean age was 58.7 years, ranging from 22 to 82. Tumor volumes were objectively calculated, treatment effects assessed on imaging and clinical data collected and correlated to the radiosurgical response. RESULTS: Mean survival after diagnosis of BSM was 11.6 months, ranging from 1.4 to 58.8 months. Margin dose ranged from 12 to 20 Gy. At first follow up, 11 (27%) patients had complete resolution of the treated lesion. At the second follow up 15 (37%) and third follow up 19 (46%) patients had a complete response. On average, there was a 64% decrease in tumor size at first follow up after treatment. 25 (61%) patients received WBRT in addition to radiosurgery; 16 (39%) received radiosurgery alone. There was no difference in overall survival between the two groups (p = 0.1324). ARE was seen in one patient who received  16 Gy to the margin of a 2.06 cm3 pontine tumor, but without correlative symptoms. One patient was treated with Bevacizumab® for progressive, but asymptomatic, edema following treatment that was not controlled by corticosteroids. CONCLUSIONS: Location in brainstem should not be a deterrent to the use of radiosurgery for these patients. The addition or exclusion of WBRT should be based on the clinical progression of the patient and within the limits of this study does not seem to impact overall survival. With improved survival as a result of better systemic therapy, these patients can benefit from better preservation of cognitive function by this strategy.

KX2-361: a novel orally bioavailable small molecule dual Src/tubulin inhibitor that provides long term survival in a murine model of glioblastoma.

PURPOSE: A major challenge to developing new therapies for patients with malignant brain tumors is that relatively few small molecule anticancer drugs penetrate the blood-brain barrier (BBB) well enough to provide therapeutically effective concentrations in brain tissue before drug exposure in non-CNS tissues results in unacceptable toxicity. METHODS: KX2-361, a member of a novel family of compounds with Src-kinase and tubulin polymerization inhibitory activity, demonstrates good oral bioavailability and readily crosses the BBB in mice. The objective of this study was to investigate the activity of KX2-361 against human and murine glioma cells and assess its therapeutic effect in a syngeneic orthotopic model of glioblastoma. RESULTS: In addition to reducing the level of Src autophosphorylation in the GL261 murine glioblastoma cell line, KX2-361 binds directly to tubulin and disrupts microtubule architecture in glioma cells maintained in culture. CONCLUSIONS: The drug is active in vivo against orthotopic GL261 gliomas in syngeneic C57BL/6 mice. Long term survival is not observed in mice lacking an adaptive immune system, indicating that KX2-361 works in concert with the host immune system to control tumor growth and promote long-term survival in the GL261 glioma model.

Survivin Monoclonal Antibodies Detect Survivin Cell Surface Expression and Inhibit Tumor Growth In Vivo.

Purpose: Survivin is an inhibitor of apoptosis protein (IAP) that is highly expressed in many cancers and represents an attractive molecule for targeted cancer therapy. Although primarily regarded as an intracellular protein with diverse actions, survivin has also been identified in association with circulating tumor exosomes.Experimental Design: We have reported that active, specific vaccination with a long peptide survivin immunogen leads to the development of survivin-specific CD8-mediated tumor cell lysis and prolongation of survival in tumor-bearing mice. In addition to cellular antitumor responses, circulating anti-survivin antibodies are detected in the serum of mice and human glioblastoma patients following vaccination with the survivin immunogen.Results: Here we demonstrate that survivin is present on the outer cell membrane of a wide variety of cancer cell types, including both murine and human glioma cells. In addition, antibodies to survivin that are derived from the immunogen display antitumor activity against murine GL261 gliomas in both flank and intracranial tumor models and against B16 melanoma as well.Conclusions: In addition to immunogen-induced, CD8-mediated tumor cell lysis, antibodies to the survivin immunogen have antitumor activity in vivo Cell-surface survivin could provide a specific target for antibody-mediated tumor immunotherapeutic approaches. Clin Cancer Res; 24(11); 2642-52. ©2018 AACR.

NCCN Guidelines Insights: Central Nervous System Cancers, Version 1.2017.

For many years, the diagnosis and classification of gliomas have been based on histology. Although studies including large populations of patients demonstrated the prognostic value of histologic phenotype, variability in outcomes within histologic groups limited the utility of this system. Nonetheless, histology was the only proven and widely accessible tool available at the time, thus it was used for clinical trial entry criteria, and therefore determined the recommended treatment options. Research to identify molecular changes that underlie glioma progression has led to the discovery of molecular features that have greater diagnostic and prognostic value than histology. Analyses of these molecular markers across populations from randomized clinical trials have shown that some of these markers are also predictive of response to specific types of treatment, which has prompted significant changes to the recommended treatment options for grade III (anaplastic) gliomas.

Impact of the Number of Metastatic Tumors Treated by Stereotactic Radiosurgery on the Dose to Normal Brain: Implications for Brain Protection.

PURPOSE/OBJECTIVES: The purpose of this study was to evaluate the effect of the number of brain lesions for which stereotactic radiosurgery (SRS) was performed on the dose volume relationships in normal brain. MATERIALS AND METHODS: Brain tissue was segmented using the patient's pre-SRS MRI. For each plan, the following data points were recorded: total brain volume, number of lesions treated, volume of brain receiving 8 Gy (V8), V10, V12, and V15. RESULTS: A total of 225 Gamma Knife® treatments were included in this retrospective analysis. The number of lesions treated ranged from 1 to 29. The isodose for prescription ranged from 40 to 95% (mean 55%). The mean prescription dose to tumor edge was 18 Gy. The mean coverage, selectivity, conformity, and gradient index were 97.5%, 0.63, 0.56, and 3.5, respectively. The mean V12 was 9.5 cm3 (ranging from 0.5 to 59.29). There was no correlation between the number of lesions and brain V8, V12, V10, or V15. There was a direct and statistically significant relationship between the brain volume treated (V8, V10, V12, and V15) and total volume of tumors treated (p < 0.001). In our study, the integral dose to the brain exceeded 3 J when the total tumor volume exceeded 25 cm3. CONCLUSIONS: The number of metastatic brain lesions treated bears no significant relationship to total brain tissue volume treated when using SRS. The fact that the integral dose to the brain exceeded 3 J when the total tumor volume exceeded 25 cm3 is useful for establishing guidelines. Although standard practice has favored using whole brain radiation therapy in patients with more than 4 lesions, a significant amount of normal brain tissue may be spared by treating these patients with SRS. SRS should be carefully considered in patients with multiple brain lesions, with the emphasis on total brain volume involved rather than the number of lesions to be treated.

Circulating CD9+/GFAP+/survivin+ exosomes in malignant glioma patients following survivin vaccination.

Glioma cells release exosomes in culture and into the extracellular matrix in vivo. These nanobodies transport an array of biomolecules and are capable of mediating cell-cell communication. Circulating exosomes in cancer patients may be indicative of disease status and response to therapy. The inhibitor of apoptosis protein (IAP) survivin (SVN) promotes cancer cell proliferation, local immune suppression and resistance to chemotherapy and it is a potential cancer biomarker. We used imaging flow cytometry to perform quantitative measurements of circulating SVN+ exosomes in the serum of malignant glioma patients undergoing investigational treatment with an anti-survivin vaccine (SurVaxM). Serum from glioma patients contained abundant CD9+ exosomes with both SVN and glial fibrillary acidic protein (GFAP) on their surface. Survivin and GFAP were evaluated both independently and together as possible tumor markers on CD9+ exosomes. Patients with longer time to tumor progression generally exhibited a decrease in circulating CD9+/SVN+ and CD9+/GFAP+/SVN+ exosomes immediately following survivin vaccination; whereas, those with early tumor progression had an increase in exosomes, despite anti-survivin immunotherapy. Serum from non-cancer healthy control individuals had very few detectable CD9+/GFAP+/SVN+ exosomes, although CD9+/GFAP+ exosomes were detectable in small numbers. This study demonstrates that patients with malignant gliomas have CD9+/GFAP+/SVN+ and CD9+/SVN+ exosomes that are released into the circulation and that early reductions in their numbers following anti-survivin immunotherapy might be associated with longer progression-free survival.