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Glioblastoma is a devastating disease with poor prognosis. Few effective chemotherapeutics are currently available, and much effort has been expended to identify new drugs capable of slowing tumor progression. The phase 0 trial design was developed to facilitate early identification of promising agents for cancer that should undergo accelerated approval. This design features an early in-human study that enrolls a small number of patients who receive subtherapeutic doses of medication with the goals of describing pharmacokinetics through drug blood level measurements and determining intratumoral concentrations of the investigational compound as well as pharmacodynamics by studying the biochemical and physiological effects of drugs. In neuro-oncology, however, the presence of the blood-brain barrier and difficulty in obtaining brain tumor tissue warrant a separate set of considerations. In this paper, we critically reviewed the protocols used in all brain tumor related in-human phase 0 and phase 0-like ("window of opportunity") studies between 1993 and 2018, as well as ongoing clinical trials, and identified major challenges in trial design as applied to central nervous system tumors that include surgical specimen collection and storage, brain tumor drug level analysis, and confirmation of drug action. We therefore propose that phase 0 trials in neuro-oncology should include (i) only patients in whom a resection of the tumor is planned, (ii) use of clinical doses of an investigational agent, (iii) tissue sampling from enhancing and non-enhancing portions of the tumor, and (iv) assessment of drug-specific target effects. Standardization of clinical protocols for phase 0/window of opportunity studies can help accelerate the development of effective treatments for glioblastoma.

Multiciliated ependymal (E1) cells line the brain ventricles and are essential for brain homeostasis. We previously identified in the lateral ventricles a rare ependymal subpopulation (E2) with only two cilia and unique basal bodies. Here we show that E2 cells form a distinct biciliated epithelium extending along the ventral third into the fourth ventricle. In the third ventricle floor, apical profiles with only primary cilia define an additional uniciliated (E3) epithelium. E2 and E3 cells ultrastructure, marker expression and basal processes indicate that they correspond to subtypes of tanycytes. Using sonic hedgehog lineage tracing, we show that the third and fourth ventricle E2 and E3 epithelia originate from the anterior floor plate. E2 and E3 cells complete their differentiation 2-3 weeks after birth, suggesting a link to postnatal maturation. These data reveal discrete bands of E2 and E3 cells that may relay information from the CSF to underlying neural circuits along the ventral midline.

Glioblastomas (GBM) are the most aggressive and prevalent form of gliomas with abysmal prognosis and limited treatment options. We analyzed clinically relevant molecular aberrations suggestive of response to therapies in 1035 GBM tumors. Our analysis revealed mutations in 39 genes of 48 tested. IHC revealed expression of PD-L1 in 19% and PD-1 in 46%. MGMT-methylation was seen in 43%, EGFRvIII in 19% and 1p19q co-deletion in 2%. TP53 mutation was associated with concurrent mutations, while IDH1 mutation was associated with MGMT-methylation and TP53 mutation and was mutually exclusive of EGFRvIII mutation. Distinct biomarker profiles were seen in GBM compared with WHO grade III astrocytoma, suggesting different biology and potentially different treatment approaches. Analysis of 17 metachronous paired tumors showed frequent biomarker changes, including MGMT-methylation and EGFR aberrations, indicating the need for a re-biopsy for tumor profiling to direct subsequent therapy. MGMT-methylation, PR and TOPO1 appeared as significant prognostic markers in sub-cohorts of GBM defined by age. The current study represents the largest biomarker study on clinical GBM tumors using multiple technologies to detect gene mutation, amplification, protein expression and promoter methylation. These data will inform planning for future personalized biomarker-based clinical trials and identifying effective treatments based on tumor biomarkers.

Recovery from organ-specific autoimmune diseases largely relies on the mobilization of endogenous repair mechanisms and local factors that control them. Natural killer (NK) cells are swiftly mobilized to organs targeted by autoimmunity and typically undergo numerical contraction when inflammation wanes. We report the unexpected finding that NK cells are retained in the brain subventricular zone (SVZ) during the chronic phase of multiple sclerosis in humans and its animal model in mice. These NK cells were found preferentially in close proximity to SVZ neural stem cells (NSCs) that produce interleukin-15 and sustain functionally competent NK cells. Moreover, NK cells limited the reparative capacity of NSCs following brain inflammation. These findings reveal that reciprocal interactions between NSCs and NK cells regulate neurorepair.

Despite its critical importance to global brain function, the postnatal development of the human pons remains poorly understood. In the present study, we first performed magnetic resonance imaging (MRI)-based morphometric analyses of the postnatal human pons (0-18 years; n = 6-14/timepoint). Pons volume increased 6-fold from birth to 5 years, followed by continued slower growth throughout childhood. The observed growth was primarily due to expansion of the basis pontis. T2-based MRI analysis suggests that this growth is linked to increased myelination, and histological analysis of myelin basic protein in human postmortem specimens confirmed a dramatic increase in myelination during infancy. Analysis of cellular proliferation revealed many Ki67(+) cells during the first 7 months of life, particularly during the first month, where proliferation was increased in the basis relative to tegmentum. The majority of proliferative cells in the postnatal pons expressed the transcription factor Olig2, suggesting an oligodendrocyte lineage. The proportion of proliferating cells that were Olig2(+) was similar through the first 7 months of life and between basis and tegmentum. The number of Ki67(+) cells declined dramatically from birth to 7 months and further decreased by 3 years, with a small number of Ki67(+) cells observed throughout childhood. In addition, two populations of vimentin/nestin-expressing cells were identified: a dorsal group near the ventricular surface, which persists throughout childhood, and a parenchymal population that diminishes by 7 months and was not evident later in childhood. Together, our data reveal remarkable postnatal growth in the ventral pons, particularly during infancy when cells are most proliferative and myelination increases.

The subventricular zone of many adult non-human mammals generates large numbers of new neurons destined for the olfactory bulb. Along the walls of the lateral ventricles, immature neuronal progeny migrate in tangentially oriented chains that coalesce into a rostral migratory stream (RMS) connecting the subventricular zone to the olfactory bulb. The adult human subventricular zone, in contrast, contains a hypocellular gap layer separating the ependymal lining from a periventricular ribbon of astrocytes. Some of these subventricular zone astrocytes can function as neural stem cells in vitro, but their function in vivo remains controversial. An initial report found few subventricular zone proliferating cells and rare migrating immature neurons in the RMS of adult humans. In contrast, a subsequent study indicated robust proliferation and migration in the human subventricular zone and RMS. Here we find that the infant human subventricular zone and RMS contain an extensive corridor of migrating immature neurons before 18 months of age but, contrary to previous reports, this germinal activity subsides in older children and is nearly extinct by adulthood. Surprisingly, during this limited window of neurogenesis, not all new neurons in the human subventricular zone are destined for the olfactory bulb--we describe a major migratory pathway that targets the prefrontal cortex in humans. Together, these findings reveal robust streams of tangentially migrating immature neurons in human early postnatal subventricular zone and cortex. These pathways represent potential targets of neurological injuries affecting neonates.

The evaluation and management of patients with residual Cushing's disease is one of the more complex issues facing neurosurgeons and neuroendocrinologists in clinical practice. There is considerable controversy over several relevant issues such as the timing of the assessment of whether a patient is in remission, what biochemical parameters define remission, the most appropriate course of action to take after residual disease has been defined, etc. As a consequence of the controversies, treating physicians develop notions and fall into certain practice patterns based on evidence of varying levels, their anecdotal experiences, and information gleaned from scientific meetings. This practice pattern, we believe, constitutes the "art of medicine." We conducted a PubMed literature search to identify manuscripts containing data relevant to Cushing's disease, outcomes of various therapeutic modalities, and recurrences. Reference lists were used to identify additional relevant manuscripts. We focused our review on manuscripts that included reasonably large series of patients, those reflecting the experience of pituitary centers and physicians recognized as experts in the field, and those papers felt to represent seminal contributions to the literature. Furthermore, trends in the evaluation and management of relevant patients have been incorporated by the senior author who has seen and evaluated over 750 patients with documented Cushing's syndrome over the past 18 years in clinical practice. An analysis of current evidence indicated that, despite advances in neurosurgical techniques and recent developments in adjuvant therapies, patients with residual Cushing's disease present significant management challenges to treating physicians. In this era, however, it is indeed possible to gain control of the hypercortisolism in most patients. Despite the wide variability in research methodology designed to collect relevant data, a step-wise approach to the management of these patients can be achieved. A logical step-wise approach to the evaluation of postoperative patients with Cushing's disease is essential. Patients with residual disease require the development of an individualized plan of management that takes into account numerous factors pertaining to status of disease, the experience of treating physicians, and available therapeutic modalities.