Marta Couce

A Three-Dimensional Organoid Culture System Derived from Human Glioblastomas Recapitulates the Hypoxic Gradients and Cancer Stem Cell Heterogeneity of Tumors Found In Vivo.

Many cancers feature cellular hierarchies that are driven by tumor-initiating cancer stem cells (CSC) and rely on complex interactions with the tumor microenvironment. Standard cell culture conditions fail to recapitulate the original tumor architecture or microenvironmental gradients and are not designed to retain the cellular heterogeneity of parental tumors. Here, we describe a three-dimensional culture system that supports the long-term growth and expansion of tumor organoids derived directly from glioblastoma specimens, including patient-derived primary cultures, xenografts, genetically engineered glioma models, or patient samples. Organoids derived from multiple regions of patient tumors retain selective tumorigenic potential. Furthermore, organoids could be established directly from brain metastases not typically amenable to in vitro culture. Once formed, tumor organoids grew for months and displayed regional heterogeneity with a rapidly dividing outer region of SOX2(+), OLIG2(+), and TLX(+) cells surrounding a hypoxic core of primarily non-stem senescent cells and diffuse, quiescent CSCs. Notably, non-stem cells within organoids were sensitive to radiotherapy, whereas adjacent CSCs were radioresistant. Orthotopic transplantation of patient-derived organoids resulted in tumors displaying histologic features, including single-cell invasiveness, that were more representative of the parental tumor compared with those formed from patient-derived sphere cultures. In conclusion, we present a new ex vivo model in which phenotypically diverse stem and non-stem glioblastoma cell populations can be simultaneously cultured to explore new facets of microenvironmental influences and CSC biology. Cancer Res; 76(8); 2465-77. ©2016 AACR.

Morphological and molecular features of astroblastoma, including BRAFV600E mutations, suggest an ontological relationship to other cortical-based gliomas of children and young adults

Background. Astroblastomas (ABs) are rare glial tumors showing overlapping features with astrocytomas, ependymomas, and sometimes other glial neoplasms, and may be challenging to diagnose. Methods. We examined clinical, histopathological, and molecular features in 28 archival formalin-fixed, paraffin-embedded AB cases and performed survival analyses using Cox proportional hazards and Kaplan–Meier methods. Results. Unlike ependymomas and angiocentric gliomas, ABs demonstrate abundant distinctive astroblastic pseudorosettes and are usually Olig2 immunopositive. They also frequently exhibit rhabdoid cells, multinucleated cells, and eosinophilic granular material. They retain immunoreactivity to alpha thalassemia/mental retardation syndrome X-linked, are immunonegative to isocitrate dehydrogenase-1 R132H mutation, and only occasionally show MGMT promoter hypermethylation differentiating them from many diffuse gliomas. Like pleomorphic xanthoastrocytoma, ganglioglioma, supratentorial pilocytic astrocytoma, and other predominantly cortical-based glial tumors, ABs often harbor the BRAFV600E mutation, present in 38% of cases tested (n = 21), further distinguishing those tumors from ependymomas and angiocentric gliomas. Factors correlating with longer patient survival included age less than 30 years, female gender, absent BRAFV600E , and mitotic index less than 5 mitoses/10 high-power fields; however, only the latter was significant by Cox and Kaplan–Meier analyses (n = 24; P = .024 and .012, respectively). This mitotic cutoff is therefore currently the best criterion to stratify tumors into low-grade ABs and higher-grade anaplastic ABs. Conclusions. In addition to their own characteristic histological features, ABs share some molecular and histological findings with other, possibly ontologically related, cortical-based gliomas of mostly children and young adults. Importantly, the presence of BRAFV600E mutations in a subset of ABs suggests potential clinical utility of targeted anti-BRAF therapy.

Completeness and concordancy of WHO grade assignment for brain and central nervous system tumors in the United States, 2004–2011

Central nervous system (CNS) tumors are categorized and graded for clinical and research purposes according to the World Health Organization (WHO) scheme which segregates tumors by histological type and predicted biological behavior. However, reporting of WHO grade in pathological reports is inconsistent despite its collection in cancer registration. We studied the completeness, concordancy, and yearly trends in the collection of WHO grade for primary CNS tumors between 2004 and 2011. Data from the Surveillance, Epidemiology and End Results program were analyzed for the percentage of histologically diagnosed primary CNS tumor cases with concordantly documented WHO grades between 2004 and 2011. Yearly trends were calculated with annual percentage changes (APC) and 95xa0% confidence intervals (95xa0% CI). Completeness and concordancy of the collection of WHO grade varied significantly by histological type and year. The percentage of cases with documented WHO grade increased significantly from 2004 to 2011: 39.0xa0% of cases in 2004 had documented WHO grade, while 77.5xa0% of cases had documented grade in 2011 (APC, 10.3; 95xa0% CI: 9.0, 11.5). Among cases with documented WHO grade, the percentage graded concordantly increased significantly from 89.1xa0% in 2004 to 93.7xa0% in 2007 (APC, 1.8; 95xa0% CI: 1.0, 2.6) and these values varied over time by histological type. One common trend among all histologies was a significant increase in the percentage of cases with documented WHO grade. A sizeable proportion of reported CNS tumors collected by cancer registrars have undocumented WHO grade, while a much smaller proportion are graded discordantly. Data collection on grade has improved in completeness and concordancy over time. Efforts to further improve collection of this variable are essential for clinical care and the epidemiological surveillance of CNS tumors.

Is all inflammation within temporal artery biopsies temporal arteritis

Temporal arteritis peaks during the eighth decade, affecting patients with frequent comorbidities who are especially prone to adverse effects of corticosteroid therapy. Perivascular inflammation involving small periadventitial vessels is not uncommon in otherwise normal temporal artery biopsies (TABs). As ischemic events occur in patients with non-temporal artery--based inflammation, it has been recommended that any vascular inflammation within TABs be treated with corticosteroids. We sought to determine whether such patients are at increased risk for temporal arteritis-like adverse events compared with age-matched controls devoid of inflammatory infiltrates. TABs without transmural temporal arteritic damage accessioned between 2002 and 2012 were reviewed for inflammation (>15 perivascular lymphocytes) involving small blood vessels and/or temporal artery adventitia. Of 343 TABs, 278 (81%) were negative for transmural arteritis. Inflammation involving small vessels and/or temporal artery adventitia was present in 56 cases (20%). Age-matched controls were available for 39 cases. With a mean follow-up of 5 years (range, 1-11 years), 6/39 (15%) of patients developed stroke or cardiovascular events or died compared with 7/39 (18%) of age-matched controls. None of the patients with study-positive TAB had documented steroid therapy before or after TAB. Our results demonstrate that patients with inflammation involving only small vessels or temporal artery adventitia are not at increased risk for temporal arteritis-like adverse events, and suggest that the risks of protracted corticosteroid therapy in this elderly population likely exceed any potential benefits. We advise against diagnosing vasculitis in the absence of temporal arteritic damage.

Secondary diffuse large B cell lymphoma of the central nervous system: retrospective review of case series

Dear Editor, The primary central nervous system (CNS) diffuse large B cell lymphoma (DLBCL) has a significantly more aggressive clinical course compared to systemic DLBCL. Secondary CNS DLBCL has been associated with immunosuppression, autoimmune disease, and transplantation [1, 2] and is excluded from primary DLBCL in the 2016 WHO classification of lymphomas [3]. Secondary isolated CNS relapse is rare, with poorly defined management strategies [4–7]. We set out to identify and further characterize secondary CNS DLBCL in our patient population. A search of our pathology archives from 2000 to 2016 identified 55 cases of DLBCL. After clinical and pathological review, patients were divided into primary and secondary CNS DLBCL. The secondary lymphomas were further subclassified as germinal center (GC) and activated B cells (ABC) using the Hans algorithm [8]. Clinical information is summarized in Table 1. Forty-eight primary CNS DLBCLs were identified, with an average age of 67 and a slight male predominance of 1.2:1. Ninety-eight percent were Caucasian. Seven secondary DLBCLs were identified, and further divided into metachronous and synchronous lymphomas. Five metachronous CNS DLBCLs occurred at an average age of 58 and M:F ratio of 3:2. All showed ABC phenotypic expression and an average of 7 years between initial systemic presentation and CNS relapse. Two had a transplantation history (one of whom was treated with mycophenolate) and one had history of autoimmune disease. The time from the CNS diagnosis to last follow-up ranged from 5 to 48 months. Two of the seven metachronous cases had divergent lymphoma phenotypes, with initial diagnoses of mixed small and large cell lymphoma and cutaneous B cell lymphoma. The two synchronous DLBCLs both occurred in male patients at an average age of 52; one of these patients was HIV positive and showed EBER expression and GC phenotype. The second patient had no history of transplantation, autoimmunity, or immunosuppression. Variations in therapeutic chemotherapy, rituximab and radiation did not appear to affect the outcome in our limited data set. The high prevalence of the ABC phenotype among these secondary CNS lymphomas partly explains the dismal outcome in these patients [9]. Although our case series is not large enough to perform statistical analysis, our findings indicate an increased incidence of secondary DLBCL in patients with autoimmunity, transplantation, and immunosuppression, which is concordant with previous reports [1, 2]. DLBCL of the CNS in these settings should be distinguished from primary DLBCL of the CNS [3]. The relatively long period before the CNS relapse is unique in the metachronous group and may result in under diagnosis of secondary CNS DLBCL. Further studies are required to understand the pathophysiology and prognosis of secondary DLBCL of the CNS. * Hammad Tashkandi hammadnmt@yahoo.com

Brain tumor biobanking in the precision medicine era: Building a high-quality resource for translational research in neuro-oncology

The growth of precision medicine has made access to biobanks with high-quality, well-annotated neuro-oncology biospecimens critical. Developing and maintaining neuro-oncology biobanks is best accomplished through multidisciplinary collaboration between clinicians and researchers. Balancing the needs and leveraging the skills of all stakeholders in this multidisciplinary effort is of utmost importance. Collaboration with a multidisciplinary team of clinicians, health care team members, and institutions, as well as patients and their families, is essential for access to participants in order to obtain informed consent, collect samples under strict standard operating procedures, and accurate and relevant clinical annotation. Once a neuro-oncology biobank is established, development and implementation of policies related to governance and distribution of biospecimens (both within and outside the institution) is of critical importance for sustainability. Proper implementation of a governance process helps to ensure that the biospecimens and data can be utilized in research with the largest potential benefit. New NIH and peer-reviewed journal policies related to public sharing of omic data generated from stored biospecimens create new ethical challenges that must be addressed in developing informed consents, protocols, and standard operating procedures. In addition, diversification of sources of funding for the biobanks is needed for long-term sustainability.