Oncolytic virus therapy of multiple tumors in the brain requires suppression of innate and elicited antiviral responses.

The occurrence of multiple tumors in an organ heralds a rapidly fatal course. Although intravascular administration may deliver oncolytic viruses/vectors to each of these tumors, its efficiency is impeded by an antiviral activity present in complement-depleted plasma of rodents and humans. Here, this activity was shown to interact with complement in a calcium-dependent fashion, and antibody neutralization studies indicated preimmune IgM has a contributing role. Short-term exposure to cyclophosphamide (CPA) partially suppressed this activity in rodents and humans. At longer time points, cyclophosphamide also abrogated neutralizing antibody responses. Cyclophosphamide treatment of rats with large single or multiple intracerebral tumors substantially increased viral survival and propagation, leading to neoplastic regression.

KLF6 depletion promotes NF-κB signaling in glioblastoma.

Dysregulation of the NF-κB transcription factor occurs in many cancer types. Krüppel-like family of transcription factors (KLFs) regulate the expression of genes involved in cell proliferation, differentiation and survival. Here, we report a new mechanism of NF-κB activation in glioblastoma through depletion of the KLF6 tumor suppressor. We show that KLF6 transactivates multiple genes negatively controlling the NF-κB pathway and consequently reduces NF-κB nuclear localization and downregulates NF-κB targets. Reconstitution of KLF6 attenuates their malignant phenotype and induces neural-like differentiation and senescence, consistent with NF-κB pathway inhibition. KLF6 is heterozygously deleted in 74.5% of the analyzed glioblastomas and predicts unfavorable patient prognosis suggesting that haploinsufficiency is a clinically relevant means of evading KLF6-dependent regulation of NF-κB. Together, our study identifies a new mechanism by which KLF6 regulates NF-κB signaling, and how this mechanism is circumvented in glioblastoma through KLF6 loss.

Human gliomas with wild-type p53 express bcl-2.

Human astrocytomas frequently overexpress wild-type p53, which suggests that gliomas have evolved a mechanism to subvert p53-mediated apoptosis. bcl-2 inhibits apoptosis mediated by p53, and it is expressed in several human cancers. We therefore examined a series of human gliomas to determine whether bcl-2 is expressed and whether this expression is associated with tumors which have wild-type p53. Twenty-eight paraffin-embedded gliomas (3 WHO grade II, 13 grade III, 12 grade IV) were immunohistochemically stained for bcl-2 and p53. p53 mutations were identified with single strand conformation polymorphism and DNA sequencing. Sixteen of 28 (57%) tumors expressed bcl-2, and bcl-2 expression was associated with wild-type p53 (P < 0.01). Among gliomas which overexpressed p53, bcl-2 was positive in 7 of 7 tumors with wild-type p53 but in only 1 of 7 with mutant p53 (P < 0.01). We conclude that bcl-2 is frequently expressed in human gliomas and that expression is more common in tumors with wild-type p53.

Computational Identification of Tumor Anatomic Location Associated with Survival in 2 Large Cohorts of Human Primary Glioblastomas.

BACKGROUND AND PURPOSE: Tumor location has been shown to be a significant prognostic factor in patients with glioblastoma. The purpose of this study was to characterize glioblastoma lesions by identifying MR imaging voxel-based tumor location features that are associated with tumor molecular profiles, patient characteristics, and clinical outcomes. MATERIALS AND METHODS: Preoperative T1 anatomic MR images of 384 patients with glioblastomas were obtained from 2 independent cohorts (n = 253 from the Stanford University Medical Center for training and n = 131 from The Cancer Genome Atlas for validation). An automated computational image-analysis pipeline was developed to determine the anatomic locations of tumor in each patient. Voxel-based differences in tumor location between good (overall survival of >17 months) and poor (overall survival of <11 months) survival groups identified in the training cohort were used to classify patients in The Cancer Genome Atlas cohort into 2 brain-location groups, for which clinical features, messenger RNA expression, and copy number changes were compared to elucidate the biologic basis of tumors located in different brain regions. RESULTS: Tumors in the right occipitotemporal periventricular white matter were significantly associated with poor survival in both training and test cohorts (both, log-rank P < .05) and had larger tumor volume compared with tumors in other locations. Tumors in the right periatrial location were associated with hypoxia pathway enrichment and PDGFRA amplification, making them potential targets for subgroup-specific therapies. CONCLUSIONS: Voxel-based location in glioblastoma is associated with patient outcome and may have a potential role for guiding personalized treatment.

Regression of experimental brain tumors with 6-thioxanthine and Escherichia coli gpt gene therapy.

The identification of transgenes with antitumor activity is critical to the development of gene therapy of cancer. Retrovirus-mediated transfer of the Escherichia coli gpt gene into rat C6 glioma cells without subsequent selection still inhibited the proliferation of this mixed polyclonal population upon addition of the prodrug, 6-thioxanthine, with an ID50 of 4.1 microM, whereas parental C6 cells were not affected at a concentration of 500 microM. In a time-course assay, effects of the prodrug on the mixed polyclonal cell proliferation required at least 10 days of exposure. In mixed co-cultures, a bystander effect was not present over the first 4 days of prodrug exposure, but required trypsinization of the co-cultures and replating at lower densities. This "modified" bystander assay thus revealed a 50% decrease in C6 cell proliferation, even when the initial ratio of gpt-expressing to parental C6 cells was as low as 1:19. In a nude mouse model of subcutaneous tumors, co-grafts of C6 glioma and gpt-retrovirus producer cells displayed retarded growth upon exposure to 6-thioxanthine (6-TX). In a nude mouse model of intracerebral tumors, grafting of the gpt-retrovirus producer cells leads to an 80% reduction in intracerebral tumor volumes after 6-TX treatment. This reduction results in a 28% increase in the mean time of survival of animals that harbor intracerebral tumors (p < 0.0005). These antitumor effects indicate that the gpt/6-TX enzyme/prodrug pair is a promising alternative to the thymidine kinase gene and ganciclovir combination in the gene therapy of cancer.

Chromosome 19q deletions in human gliomas overlap telomeric to D19S219 and may target a 425 kb region centromeric to D19S112.

Chromosome 19q harbors a tumor suppressor gene that is involved in astrocytoma, oligodendroglioma and mixed glioma tumorigenesis. We had previously mapped this gene to an approximately 5 megabase region of chromosome 19q13.2-13.3 between APOC2 and HRC. To narrow the location of this tumor suppressor further, we studied 138 gliomas for loss of allelic heterozygosity at six microsatellite polymorphisms between APOC2 and HRC, including a newly described polymorphism in the ERCC2 gene. Allelic loss occurred in 48 gliomas (35%), including 25 of 41 oligodendroglial tumors (61%). Four cases had proximal breakpoints within the APOC2-HRC region, two telomeric to ERCC2 and two telomeric to D19S219. In addition, one of the latter tumors had an interstitial deletion between D19S219 and D19S112, a distance of only 425 kilobases surrounding the DM (myotonic dystrophy) gene. These findings suggest that the glioma tumor suppressor on chromosome 19q maps to 19q13.3, telomeric to D19S219 and perhaps centromeric to D19S112. The data exclude a number of candidate genes from 19q13.2-13.3, including a putative phosphatase gene and the DNA repair/metabolism genes ERCC1, ERCC2 and probably LIG1.

Retrovirus-mediated gene therapy of experimental brain neoplasms using the herpes simplex virus-thymidine kinase/ganciclovir paradigm.

Recent results in experimental brain tumors indicate that transfer of sensitizing genes to tumor cells in vivo with subsequent drug treatment can reduce tumor masses and prolong the survival of rodents. In the present study, the 9L rat gliosarcoma model was used to evaluate the therapeutic effectiveness of the herpes simplex virus-thymidine kinase (HSV-tk) gene, delivered by a retrovirus vector, against tumor cells in the rat brain after systemic application of the nucleoside analogue ganciclovir (GCV). The HSV-tk gene was inserted into a retroviral vector (pMFG), which was produced using the amphotropic packaging cell line CRIP-MFG-S-HSV-TK. Packaging cells were implanted into established 9L tumors in the brains of syngeneic rats to effect gene delivery to tumor cells, followed by intraperitoneal GCV injections. Treated animals survived significantly longer (more than twice as long) than did the control groups. Brains from GCV-treated and nontreated animals were examined immunohistochemically at different time intervals after grafting of CRIP-MFG-S-HSV-TK cells and GCV treatment. Tumors in GCV-treated animals were significantly smaller as compared with nontreated animals at all time points. Sections stained immunohistochemically for HSV-TK confirmed gene transfer to tumor cells, which could be distinguished from packaging cells by different morphology and immunohistochemical staining for the retroviral envelope protein gp70. Approximately 45% of the cells in tumors implanted with CRIP-MFG-S-HSV-TK cells, but not treated with GCV, showed immunocytochemical staining for HSV-TK, demonstrating a high-efficiency of retrovirus-mediated gene transfer. Tumors in rats treated with packaging cells and GCV showed only 9% HSV-TK-positive cells after treatment, indicating that most cells expressing the HSV-tk gene were killed. The success of this therapeutic modality in experimental animals depends in large parts on the high efficiency of gene delivery and on the immune response against tumor cells.

Therapy of primary CNS lymphoma with methotrexate-based chemotherapy and deferred radiotherapy: preliminary results.

Disease-free survival in primary CNS lymphoma has improved with the advent of methotrexate-based pre-irradiation chemotherapy. Prolonged response durations have been noted in six of eight patients refusing radiation therapy in two of our prior series. We have treated an additional 11 patients with methotrexate-based chemotherapy without subsequent planned irradiation. Some received maintenance chemotherapy. Most have had durable responses with little or no toxicity. Prolonged responses can be maintained without radiation therapy, thus avoiding potential long-term radiation toxicity.

Von Hippel-Lindau disease and erythrocytosis: radioimmunoassay of erythropoietin in cyst fluid from a brainstem hemangioblastoma.

A 59-year-old woman with von Hippel-Lindau disease developed erythrocytosis and a recurrent intracranial hemangioblastoma. Radioimmunoassay showed an elevated level of erythropoietin in her serum. Cyst fluid from the tumor also contained erythropoietin, concentrated a thousandfold relative to the serum level. Production of erythropoietin by hemangioblastomas may explain the erythrocytosis present in some patients with von Hippel-Lindau disease.

Aneurysmal compression of the anterior visual pathways.

Ten patients with aneurysmal compression of the anterior visual pathways had visual loss, unilateral in 4 and bilateral in 6. There was no typical clinical presentation. Visual loss was acute or gradual, acuity sometimes fluctuated, and visual field testing was highly variable. The aneurysms were supraclinoid (four patients), carotid-ophthalmic (two), anterior communicating-anterior cerebral (three), and intracavernous carotid (one). Nine patients had successful clipping of their aneurysm, and in one, ipsilateral common carotid ligation was performed. Postoperatively, visual acuity was improved in six cases, unchanged in three, and worse in one.

Functional cerebral imaging in the evaluation and radiotherapeutic treatment planning of patients with malignant glioma.

PURPOSE: Functional magnetic resonance imaging (MRI) and positron emission tomography are relatively new modalities of great potential value in the evaluation, treatment, and subsequent follow-up care of patients with malignant glioma. We report our experience with the incorporation of functional imaging data into radiation therapy three-dimensional (3-D) treatment planning. METHODS AND MATERIALS: Over a 24-month period, a total of 37 positron emission tomography and 29 functional MRI studies have been conducted on eight consecutive patients prior to, during, and following the completion of radiation therapy. Functional imaging was conducted prior to radiation therapy treatment planning and at approximate 3-month follow-up time intervals. RESULTS: In two patients, functional imaging provided additional information over conventional imaging modalities and resulted in subsequent modification of conventional radiation therapy treatment planning. CONCLUSION: Although it is premature to make definitive statements regarding the use of these new imaging parameters in the prognostic setting, functional imaging may likely prove to be a useful adjunct in the initial evaluation, radiation treatment planning, and follow-up care of patients with malignant glioma.

A multi-institutional experience with stereotactic radiosurgery for solitary brain metastasis.

PURPOSE: A multi-institutional experience in radiosurgery for solitary brain metastases was combined to identify factors associated with safety, efficacy, tumor control, and survival. MATERIALS AND METHODS: A review of 116 patients with solitary brain metastases who underwent gamma knife stereotactic radiosurgery at five institutions was performed. The median follow-up was 7 months following radiosurgery and 12 months following diagnosis. Minimum tumor doses varied from 8-30 Gy (mean, 17.5 Gy). Forty-five patients failed prior radiotherapy and 71 had no prior brain irradiation. Fifty-one patients had radiosurgery alone and 65 underwent combined radiosurgery with fractionated large-field radiotherapy (mean dose, 33.8 Gy). RESULTS: Median survival was 11 months after radiosurgery and 20 months after diagnosis. Follow-up documented local tumor control in 99 patients (85%), tumor recurrence in 17 (15%), and documented radiation necrosis in one (1%). The 2-year actuarial tumor control rate was 67 +/- 8%. Tumor histology affected survival (better for breast cancer, p = .004) and local control (better for melanoma and renal cell, p = .0003) in multivariate analyses. Combined fractionated radiotherapy and radiosurgery improved local control (p = 0.111), but not survival in multivariate testing. CONCLUSION: Radiosurgery is effective in controlling solitary brain metastases with low morbidity. Further study is needed to better define optimum treatment parameters for radiosurgery.

Giant epidermoid involving 3 cranial bones.

We describe a patient with an incidental finding of an expansile osteolytic lesion centered in the sphenoid involving 3 cranial bones-frontal, temporal, and sphenoid-and invading the brain parenchyma and orbit. Biopsy demonstrated an epidermoid. The lesion was excised through frontotemporal craniotomy. Despite the benign nature of the tumor, the epidermoid had a destructive pattern of growth. Complete resection was needed to adequately address the inflammatory mass effect of the large lesion.

Lymphomatous optic neuropathy.

Optic neuropathy as the first sign of a lymphoreticular neoplasm is rare. A 65-year-old man complained of initially transient and then progressive visual loss in the right eye for two weeks. Computed tomography demonstrated a mass in the region of the intracranial portion of the right optic nerve. Frontal craniotomy was performed and histopathologic examination of the tumor disclosed a granulomatous process. Regrowth of the mass and visual deterioration, despite systemic steroid therapy, prompted surgical reexploration. Histopathologic examination confirmed large cell lymphoma. After local radiotherapy (2,500 rad), the patient is well and free of local or systemic lymphoma one year later. Other reported cases of lymphomatous optic neuropathy are reviewed and the diagnostic difficulties encountered are discussed.

Echo-planar MR determination of relative cerebral blood volume in human brain tumors: T1 versus T2 weighting.

PURPOSE: Maps related to relative cerebral blood volume (rCBV) were generated with the use of the T1 effects produced by a low-dose bolus passage of gadopentetate dimeglumine. The T1 maps were evaluated in a tumor population and compared with rCBV maps obtained with T2-weighted measurements. METHODS: Imaging was performed in 19 patients with suspected intraaxial brain tumors. For the T1 rCBV maps, a low-dose bolus of contrast material was given during T1-weighted interleaved spin-echo echo-planar MR imaging. This was followed by a second injection during serial T2-weighted imaging for generation of the T2 rCBV maps. RESULTS: Among patients with low-grade lesions (n = 9), T1-based and T2-based rCBV maps showed comparably low rCBV in 7 subjects. In the other 2 patients, with confirmed tumor dedifferentiation, elevation of rCBV values was seen on maps obtained with both techniques. Among patients with high-grade tumors (n = 10), 4 had no evidence of recurrence and 6 did have tumor recurrence (confirmed by follow-up and positron emission tomography). In patients with the high-grade lesions exhibiting conventional contrast enhancement, lesions tended to have higher estimated values on T1 rCBV maps than on the T2 rCBV maps. CONCLUSION: Although the T1 rCBV maps showed less contrast as compared with the T2 rCBV maps, they provided diagnostic information that was comparable to the T2 rCBV maps in our series of 19 patients with primary brain tumors.

The multiple tumor suppressor 1/cyclin-dependent kinase inhibitor 2 gene in human central nervous system primitive neuroectodermal tumor.

The recently described multiple tumor suppressor 1/cyclin-dependent kinase inhibitor 2 (MTS1/CDKN2) gene, encoding the cyclin-dependent kinase 4 inhibitor p16, is mutated in a wide variety of tumor cell lines, including gliomas. To investigate the possible role of this gene in the genesis of the central nervous system primitive neuroectodermal tumor (PNET), four established PNET cell lines and 18 PNET surgical specimens were studied for deletions and mutations of the MTS1/CDKN2 gene. One of the four cell lines had homozygous deletion of the gene. No mutation in any of the three MTS1/CDKN2 exons was detected in the other three cell lines by single strand conformational polymorphism analysis. Eighteen surgical PNET specimens were studied for allelic and homozygous deletion at chromosome 9p21, the location of the MTS1/CDKN2 gene. No loss of heterozygosity was noted in 11 of the tumors, and no homozygous loss was noted in any tumor. Single strand conformational polymorphism analysis of the entire coding region of the MTS1/CDKN2 gene revealed no mutation within MTS1/CDKN2 in any tumor. Although deletion of MTS1/CDKN2 may occur in some PNET cell lines, neither deletion nor mutation of the gene is found in tumors before culture. The genesis of the human central nervous system PNET does not involve deletion or mutation of the MTS1/CDKN2 gene.

Unilateral hydrocephalus caused by an intraventricular venous malformation obstructing the foramen of Monro.

Unilateral hydrocephalus in an adult was caused by obstruction of the left foramen of Monro by an intraventricular venous malformation. Magnetic resonance imaging of the region of the foramen of Monro demonstrated the lesion, which subsequently was confirmed to be a venous malformation by angiography and surgery.

Stereotactic radiosurgery of cavernous sinus meningiomas as an addition or alternative to microsurgery.

To evaluate the response of cavernous sinus meningiomas to stereotactic radiosurgery, we reviewed our 54-month experience with 34 patients. All patients underwent radiosurgery with a 201-source cobalt-60 gamma unit. Twenty-eight patients (82%) had previous histological confirmation of a meningioma (1 to 5 cranial base craniotomies per patient); 6 (18%) were treated on the basis of neuroimaging criteria alone. The single-fraction radiation tumor margin dose (10 to 20 Gy) was designed to conform to the irregular tumor volumes in all patients. The maximum radiation dose to the optic nerve or tract was reduced to 9 Gy in 31 patients. No patient had tumor growth (100% tumor control) during the follow-up interval (median, 26 mo). Tumor regression was observed in 56% of patients imaged at an average of 18 months. Eight patients (24%) improved clinically at follow-up examinations. Four patients developed new or worsened cranial nerve deficits during the follow-up interval; two had subsequent full improvement. No patient developed an endocrinopathy or new extraocular muscle paresis. Stereotactic radiosurgery, using multiple isocenter dosimetry facilitated by the gamma unit, is an accurate, safe, and effective technique to prevent the growth of tumors involving the cavernous sinus. Despite the proximity of such tumors to adjacent cranial nerves, complications were rare. The maximum length of hospital stay was 36 hours, and all patients returned to their preoperative employment status within 3 to 5 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Reoperation for recurrent glioblastoma and anaplastic astrocytoma.

The advisability of a second operation for recurrent glioblastoma multiforme or anaplastic astrocytoma depends on the expected duration and quality of subsequent survival. We reviewed the results in 70 consecutive patients who underwent reoperation for supratentorial glioblastoma multiforme (n = 39) or anaplastic astrocytoma (n = 31) between 1975 and 1984. The operative morbidity rate was 5.7% (4 of 70 patients); the 6-week postoperative mortality rate was 4.3% (3 of 70 patients). The median duration of survival after reoperation was 36 weeks in patients with glioblastoma multiforme and 88 weeks in those with anaplastic astrocytoma. The median duration of high quality survival (defined as the period during which the patient had a Karnofsky performance score of at least 70) after reoperation was 10 weeks for patients with glioblastoma multiforme and 83 weeks for patients with anaplastic astrocytoma. Age and preoperative Karnofsky score in patients with glioblastoma multiforme and age in patients with anaplastic astrocytoma had statistically significant effects on the duration of high quality survival after reoperation, but not on postoperative survival independent of quality. Although age and functional status do not significantly affect the duration of survival after reoperation, they do have a significant effect on the quality of life after reoperation. Frequently, a patient can expect to spend a greater portion of his life at a higher level of function than he would have without reoperation. As adjunctive forms of therapy improve, reoperation will play an increasingly prominent role in the management of recurrent malignant astrocytic tumors.

Magnetic resonance imaging of tuberculum sellae meningiomas: preventing preoperative misdiagnosis as pituitary macroadenoma.

Despite recent advances in neurodiagnostic imaging, it may be difficult to differentiate tuberculum sellae meningiomas from pituitary macroadenomas preoperatively. Magnetic resonance (MR) imaging has supplanted computed tomography as the imaging modality of choice for sellar and parasellar lesions, but unenhanced MR imaging does not reliably distinguish between all tuberculum sellae meningiomas and pituitary macroadenomas. Accurate differentiation between these alternative diagnoses of a suprasellar mass is important because a tuberculum sellae meningioma always requires a craniotomy, whereas a transsphenoidal route is preferred for removing most pituitary macroadenomas. The gadolinium-enhanced MR images of seven patients with tuberculum sellae meningioma and seven with pituitary macroadenoma were reviewed retrospectively. Although no specific radiological feature was pathognomonic, a combination of several features allowed the correct diagnosis in all cases. Three characteristics of tuberculum sellae meningiomas distinguish them from pituitary macroadenomas: 1) bright homogeneous enhancement with gadolinium, as opposed to heterogeneous, relatively poor enhancement; 2) a suprasellar rather than a sellar epicenter of tumor; and 3) tapered extension of an intracranial dural base. Each of these findings can be subtle, but careful examination of gadolinium-enhanced, high-quality, thin section coronal and sagittal MR images of the parasellar region for this constellation of findings will allow the correct preoperative diagnosis in patients with either of these tumors.