Tarik Syndrome: Reversible Postoperative Blindness Secondary to Occipital Seizures.

BACKGROUND: Postoperative blindness is a devastating surgical complication. Although usually associated with prolonged cardiac and prone spinal operations, it may follow other procedures as well. Postoperative blindness is most commonly caused by a vascular etiology, but it can more rarely be caused by status epilepticus. We have previously reported a case of this phenomenon following a staged spinal deformity surgery. CASE DESCRIPTION: Here we report 2 additional cases following a skull base procedure and a single stage lumbar spine surgery. In all instances, rapid recognition that the patients' blindness was due to occipital seizures resulted in acute antiepileptiform treatment and full restoration of vision. CONCLUSIONS: Although a rare phenomenon, this syndrome, first recognized and described by Tarik F. Ibrahim, should be considered in any patient with postoperative visual impairment.

Hitting a Moving Target: Glioma Stem Cells Demand New Approaches in Glioblastoma Therapy.

BACKGROUND: Glioblastoma multiforme (GBM) continues to devastate patients and outfox investigators and clinicians despite the preponderance of research directed at its biology, pathogenesis and therapeutic advances. GBM routinely outlasts multidisciplinary treatment protocols, almost inevitably recurring in a yet more aggressive and resistant form with distinct genetic differences from the original tumor. Attempts to glean further insight into GBM point increasingly toward a subpopulation of cells with a stem-like phenotype. These cancer stem cells, similar to those now described in a variety of malignancies, are capable of tumorigenesis from a population of susceptible cells. CONCLUSIONS: Glioma stem cells have thus become a prevalent focus in GBM research for their presumed role in development, maintenance and recurrence of tumors. Glioma stem cells infiltrate the white matter surrounding tumors and often evade resection. They are uniquely suited both biochemically and environmentally to resist the best therapy currently available, intrinsically and efficiently resistant to standard chemo- and radiotherapy. These stem cells create an extremely heterogenous tumor that to date has had an answer for every therapeutic question, with continued dismal patient survival. Targeting this population of glioma stem cells may hold the long-awaited key to durable therapeutic efficacy in GBM.

Intranasal Oncolytic Virotherapy with CXCR4-Enhanced Stem Cells Extends Survival in Mouse Model of Glioma.

The challenges to effective drug delivery to brain tumors are twofold: (1) there is a lack of non-invasive methods of local delivery and (2) the blood-brain barrier limits systemic delivery. Intranasal delivery of therapeutics to the brain overcomes both challenges. In mouse model of malignant glioma, we observed that a small fraction of intranasally delivered neural stem cells (NSCs) can migrate to the brain tumor site. Here, we demonstrate that hypoxic preconditioning or overexpression of CXCR4 significantly enhances the tumor-targeting ability of NSCs, but without altering their phenotype only in genetically modified NSCs. Modified NSCs deliver oncolytic virus to glioma more efficiently and extend survival of experimental animals in the context of radiotherapy. Our findings indicate that intranasal delivery of stem cell-based therapeutics could be optimized for future clinical applications, and allow for safe and repeated administration of biological therapies to brain tumors and other CNS disorders.

Single dose GLP toxicity and biodistribution study of a conditionally replicative adenovirus vector, CRAd-S-pk7, administered by intracerebral injection to Syrian hamsters.

BACKGROUND: CRAd-S-pk7 is a conditionally replicative oncolytic adenoviral vector that contains a survivin promoter and a pk7 fiber modification that confer tumor-specific transcriptional targeting and preferential replication in glioma while sparing the surrounding normal brain parenchyma. METHODS: This IND-enabling study performed under GLP conditions evaluated the toxicity and biodistribution of CRAd-S-pk7 administered as a single intracerebral dose to Syrian hamsters, a permissive model of adenoviral replication. Two hundred and forty animals were stereotactically administered either vehicle (n = 60) or CRAd-S-pk7 at 2.5 × 10(7), 2.5 × 10(8), or 2.5 × 10(9) viral particles (vp)/animal (each n = 60) on day 1. The animals were closely monitored for toxicology evaluation, assessment of viral distribution, and immunogenicity of CRAd-S-pk7. RESULTS: Changes in hematology, clinical chemistry, and coagulation parameters were minor and transient, and consistent with the inflammatory changes observed microscopically. These changes were considered to be of little toxicological significance. The vector remained localized primarily in the brain and to some degree in the tissues at the incision site. Low levels of vector DNA were detected in other tissues in a few animals suggesting systemic circulation of the virus. Viral DNA was detected in brains of hamsters for up to 62 days. However, microscopic changes and virus-related toxicity to the central nervous system were considered minor and decreased in incidence and severity over time. Such changes are not uncommon in studies using adenoviral vectors. CONCLUSION: This study provides safety and toxicology data justifying a clinical trial of CRAd-S-pk7 loaded in FDA-approved HB1.F3.CD neural stem cell carriers administered at the tumor resection bed in humans with recurrent malignant glioma.

Neural Stem Cells Secreting Anti-HER2 Antibody Improve Survival in a Preclinical Model of HER2 Overexpressing Breast Cancer Brain Metastases.

The treatment of human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer has been revolutionized by trastuzumab. However, longer survival of these patients now predisposes them to forming HER2 positive brain metastases, as the therapeutic antibodies cannot cross the blood brain barrier. The current oncologic repertoire does not offer a rational, nontoxic targeted therapy for brain metastases. In this study, we used an established human neural stem cell line, HB1.F3 NSCs and generated a stable pool of cells secreting a high amount of functional full-length anti-HER2 antibody, equivalent to trastuzumab. Anti-HER2Ab secreted by the NSCs (HER2Ab-NSCs) specifically binds to HER2 overexpressing human breast cancer cells and inhibits PI3K-Akt signaling. This translates to HER2Ab-NSC inhibition of breast cancer cell growth in vitro. Preclinical in vivo experiments using HER2Ab overexpressing NSCs in a breast cancer brain metastases (BCBM) mouse model demonstrate that intracranial injection of HER2Ab-NSCs significantly improves survival. In effect, these NSCs provide tumor localized production of HER2Ab, minimizing any potential off-target side effects. Our results establish HER2Ab-NSCs as a novel, nontoxic, and rational therapeutic approach for the successful treatment of HER2 overexpressing BCBM, which now warrants further preclinical and clinical investigation.

Unlocking the promise of oncolytic virotherapy in glioma: combination with chemotherapy to enhance efficacy.

Malignant glioma is a relentless burden to both patients and clinicians, and calls for innovation to overcome the limitations in current management. Glioma therapy using viruses has been investigated to accentuate the nature of a virus, killing a host tumor cell during its replication. As virus mediated approaches progress with promising therapeutic advantages, combination therapy with chemotherapy and oncolytic viruses has emerged as a more synergistic and possibly efficacious therapy. Here, we will review malignant glioma as well as prior experience with oncolytic viruses, chemotherapy and combination of the two, examining how the combination can be optimized in the future.

Neural stem cell-mediated delivery of oncolytic adenovirus.

The use of stem cells (SCs) as carriers for therapeutic agents has now progressed to early clinical trials. These clinical trials exploring SC-mediated delivery of oncolytic adenoviruses will commence in the near future, hopefully yielding meritorious results that can provoke further scientific inquiry. Preclinical animal studies have demonstrated that SCs can be successfully loaded with conditionally-replicative adenoviruses and delivered to the tumor, whereupon they may evoke pronounced therapeutic efficacy. In this protocol, we describe the maintenance of SCs, provide an analysis of optimal adenoviral titers for SC loading, and evaluate the optimized viral loading on SCs.

The efficacy and safety of preoperative lumbar drain placement in anterior skull base surgery.

This study assesses the efficacy of preoperative lumbar drain (LD) placement prior to elective open cranial and endoscopic anterior skull base (ASB) surgery in reducing postoperative cerebrospinal fluid (CSF) leak. A retrospective review of 93 patients who underwent LD placement at our institution between 2006 and 2011 was performed. Of these patients, 43 underwent elective LD placement prior to ASB surgery; 2 patients had evidence of CSF rhinorrhea prior to surgery, and 41 had no evidence of a preoperative CSF leak. Of those 41 patients, 2 developed CSF rhinorrhea (2/41= 4.9%) as a result of surgery-all in our endoscopic patient population (N = 21; 2/21= 9.5%). No postoperative CSF leaks were noted in our open ASB surgery cohort (N = 20). Other complications were rare, but we encountered two instances of delayed malignant cerebral edema in the open ASB cohort that are discussed in detail. Overall, preoperative LD placement was found to be an effective means of preventing postoperative CSF leaks after ASB approaches, but potential and significant intracranial complications may occur in select patients that merit careful consideration prior to LD placement.