Histone deacetylase inhibitors prevent the degradation and restore the activity of glucocerebrosidase in Gaucher disease.

Gaucher disease (GD) is caused by a spectrum of genetic mutations within the gene encoding the lysosomal enzyme glucocerebrosidase (GCase). These mutations often lead to misfolded proteins that are recognized by the unfolded protein response system and are degraded through the ubiquitin-proteasome pathway. Modulating this pathway with histone deacetylase inhibitors (HDACis) has been shown to improve protein stability in other disease settings. To identify the mechanisms involved in the regulation of GCase and determine the effects of HDACis on protein stability, we investigated the most prevalent mutations for nonneuronopathic (N370S) and neuronopathic (L444P) GD in cultured fibroblasts derived from GD patients and HeLa cells transfected with these mutations. The half-lives of mutant GCase proteins correspond to decreases in protein levels and enzymatic activity. GCase was found to bind to Hsp70, which directed the protein to TCP1 for proper folding, and to Hsp90, which directed the protein to the ubiquitin-proteasome pathway. Using a known HDACi (SAHA) and a unique small-molecule HDACi (LB-205), GCase levels increased rescuing enzymatic activity in mutant cells. The increase in the quantity of protein can be attributed to increases in protein half-life that correspond primarily with a decrease in degradation rather than an increase in chaperoned folding. HDACis reduce binding to Hsp90 and prevent subsequent ubiquitination and proteasomal degradation without affecting binding to Hsp70 or TCP1. These findings provide insight into the pathogenesis of GD and indicate a potent therapeutic potential of HDAC inhibitors for the treatment of GD and other human protein misfolding disorders.

Missense mutations in the human SDHB gene increase protein degradation without altering intrinsic enzymatic function.

Mutations of succinate dehydrogenase subunit B (SDHB) play a crucial role in the pathogenesis of the most aggressive and metastatic pheochromocytomas (PHEOs) and paragangliomas (PGLs). Although a variety of missense mutations in the coding sequence of the SDHB gene have been found in PHEOs and PGLs, it has been unclear whether these mutations impair mRNA expression, protein stability, subcellular localization, or intrinsic protein function. RT-PCR and Western blot analysis of SDHB mRNA and protein expression from SDHB-related PHEOs and PGLs demonstrated intact mRNA expression but significantly reduced protein expression compared to non-SDHB PHEOs and PGLs. A pulse-chase assay of common SDHB missense mutations in transfected HeLa cell lines demonstrated that the loss of SDHB function was due to a reduction in mutant protein half-life, whereas colocalization of SDHB with mitochondria and immunoprecipitation with SDHA demonstrated intact subcellular localization and complex formation. The half-life of the SDHB protein increased after treatment with histone deacetylase inhibitors (HDACis), implicating the protein quality control machinery in the degradation of mutant SDHB protein. These findings provide the first direct mechanism of functional loss resulting from SDHB mutations and suggest that reducing protein degradation with HDACis may serve as a novel therapeutic paradigm for preventing the development of SDHB-related tumors.

Glioblastoma with deep supratentorial extension is associated with a worse overall survival.

Glioblastoma (GBM) with deep-supratentorial extension (DSE) involving the thalamus, basal ganglia and corpus collosum, poses significant challenges for clinical management. In this study, we present our outcomes in patients who underwent resection of supratentorial GBM with associated involvement of deep brain structures. We conducted a retrospective review of patients who underwent resection of GBM at our institution between 2012 and 2018. A total of 419 patients were included whose pre-operative MRI scans were reviewed. Of these, 143 (34.1%) had GBM with DSE. There were similar rates of IDH-1 mutation (9% versus 7.6%, p = 0.940) and MGMT methylation status (35.7% versus 45.2%, p = 0.397) between the two cohorts. GBM patients without evidence of DSE had higher rates of radiographic gross total resection (GTR) compared to those with DSE: 70.6% versus 53.1%, respectively (p = 0.002). The presence of DSE was not associated with decreased progression-free survival (PFS) compared to patients without DSE (mean 7.24 ± 0.97 versus 8.89 ± 0.76 months, respectively; p = 0.276), but did portend a worse overall survival (OS) (mean 10.55 ± 1.04 versus 15.02 ± 1.05 months, respectively; p = 0.003). There was no difference in PFS or OS amongst DSE and non-DSE patients who underwent GTR, but patients who harbored DSE and underwent subtotal resection had worse OS (mean 8.26 ± 1.93 versus 12.96 ± 1.59 months, p = 0.03). Our study shows that GBM patients with DSE have lower OS compared to those without DSE. This survival difference appears to be primarily related to the limited surgical extent of resection owing to the neurological deficits that may be incurred with involvement of eloquent deep brain structures.

Phase Ib Clinical Trial of IGV-001 for Patients with Newly Diagnosed Glioblastoma.

PURPOSE: Despite standard of care (SOC) established by Stupp, glioblastoma remains a uniformly poor prognosis. We evaluated IGV-001, which combines autologous glioblastoma tumor cells and an antisense oligonucleotide against IGF type 1 receptor (IMV-001), in newly diagnosed glioblastoma. PATIENTS AND METHODS: This open-label protocol was approved by the Institutional Review Board at Thomas Jefferson University. Tumor cells collected during resection were treated ex vivo with IMV-001, encapsulated in biodiffusion chambers with additional IMV-001, irradiated, then implanted in abdominal acceptor sites. Patients were randomized to four exposure levels, and SOC was initiated 4-6 weeks later. On the basis of clinical improvements, randomization was halted after patient 23, and subsequent patients received only the highest exposure. Safety and tumor progression were primary and secondary objectives, respectively. Time-to-event outcomes were compared with the SOC arms of published studies. RESULTS: Thirty-three patients were enrolled, and median follow-up was 3.1 years. Six patients had adverse events (grade ≤3) possibly related to IGV-001. Median progression-free survival (PFS) was 9.8 months in the intent-to-treat population (vs. SOC, 6.5 months; P = 0.0003). In IGV-001-treated patients who met Stupp-eligible criteria, PFS was 11.6 months overall (n = 22; P = 0.001) and 17.1 months at the highest exposure (n = 10; P = 0.0025). The greatest overall survival was observed in Stupp-eligible patients receiving the highest exposure (median, 38.2 months; P = 0.044). Stupp-eligible patients with methylated O6-methylguanine-DNA methyltransferase promoter (n = 10) demonstrated median PFS of 38.4 months (P = 0.0008). Evidence of immune activation was noted. CONCLUSIONS: IGV-001 was well tolerated, PFS compared favorably with SOC, and evidence suggested an immune-mediated mechanism (ClinicalTrials.gov: NCT02507583).

Internal Neurolysis with and without Microvascular Decompression for Trigeminal Neuralgia: Case Series.

OBJECTIVE: Microvascular decompression (MVD) has remained the first-line surgical treatment of trigeminal neuralgia when an offending vessel can be identified that is causing neurovascular compression. However, patients without neurovascular compression can either develop trigeminal neuralgia or recurrence after MVD. In addition, patients with venous and less severe arterial compression have been shown to have reduced efficacy after MVD. Internal neurolysis is a surgical technique used to separate the fascicles of the trigeminal nerve and might be a good option for patients with trigeminal neuralgia but without vascular compression. METHODS: A retrospective, institutional review board-approved medical record review was performed of adult patients with trigeminal neuralgia who had undergone internal neurolysis. The search resulted in 32 patients who had been treated from 2016 to 2019. The Barrow Neurological Institute (BNI) pain intensity scale and hypesthesia scale (HS) were used to determine the outcomes. RESULTS: The average follow-up was 20 months (range, 3-40 months). The postoperative outcomes showed a BNI pain intensity scale score of I for 50%, with excellent control in 56%, successful control in 78%, adequate control in 94%, and poor control in 6%. Significantly more patients without previous treatment had had successful pain control (95% vs. 54%). Six patients (19%) experienced pain recurrence and were significantly more likely to experience pain recurrence compared with patients without a previous procedure (39% vs. 5%). The overall BNI-HS score postoperatively was I for 28%, II for 69%, and III for 3%. CONCLUSIONS: Internal neurolysis with and without MVD has shown efficacy in treating trigeminal neuralgia in carefully selected patients.

Developing standardized titles to classify the adverse events in 7,418 cranial and spinal neurosurgical procedures.

BACKGROUND: Neurosurgical procedures are life- and function-saving but carry a risk of adverse events (AE) which can cause permanent neurologic deficits. Unfortunately, there is lack of clearly defined AEs associated with given procedures, and their reporting is non-uniform and often arbitrary. However, with an increasing number of neurosurgical procedures performed, there is a need for standardization of AEs for systematic tracking. Such a system would establish a baseline for future quality improvement strategies. OBJECTIVE: To review our institutional AEs and devise standardized titles specific to the spine, tumor, functional, and vascular neurosurgery divisions. METHODS: A review of prospective monthly-reported morbidity and mortality (M&M) conference data within the Department of Neurological Surgery was conducted from January 2017 to December 2019. An AE was defined as any mortality, an "unintended and undesirable diagnostic or therapeutic event", "an event that prolongs the patient's hospital stay", or an outcome with permanent or transient neurologic deficit. RESULTS: A total of 1096 AEs from 7418 total procedures (14.8 %) were identified. Of those, 418 (5.6 %) were in cerebrovascular, 249 (3.4 %) were in neuro-oncology and 429 (5.8 %) were in the spine & functional divisions. The most common AEs across all divisions were infection (17 %), hemorrhage (11 %) and cerebrospinal fluid (CSF) leak (7.8 %). Other AEs were indirectly related to the neurosurgical procedure, such as deep vein thrombosis or pulmonary embolism (2.7 %), or pneumothorax (0.3 %). CONCLUSION: This work illustrates standardized AEs can be implemented universally across the spectrum of neurological surgery. Standardization can help identify recurring AE patterns through better tracking.

Protein Phosphatase 2A Inhibition with LB100 Enhances Radiation-Induced Mitotic Catastrophe and Tumor Growth Delay in Glioblastoma.

Protein phosphatase 2A (PP2A) is a tumor suppressor whose function is lost in many cancers. An emerging, though counterintuitive, therapeutic approach is inhibition of PP2A to drive damaged cells through the cell cycle, sensitizing them to radiotherapy. We investigated the effects of PP2A inhibition on U251 glioblastoma cells following radiation treatment in vitro and in a xenograft mouse model in vivo. Radiotherapy alone augmented PP2A activity, though this was significantly attenuated with combination LB100 treatment. LB100 treatment yielded a radiation dose enhancement factor of 1.45 and increased the rate of postradiation mitotic catastrophe at 72 and 96 hours. Glioblastoma cells treated with combination LB100 and radiotherapy maintained increased γ-H2AX expression at 24 hours, diminishing cellular repair of radiation-induced DNA double-strand breaks. Combination therapy significantly enhanced tumor growth delay and mouse survival and decreased p53 expression 3.68-fold, compared with radiotherapy alone. LB100 treatment effectively inhibited PP2A activity and enhanced U251 glioblastoma radiosensitivity in vitro and in vivo. Combination treatment with LB100 and radiation significantly delayed tumor growth, prolonging survival. The mechanism of radiosensitization appears to be related to increased mitotic catastrophe, decreased capacity for repair of DNA double-strand breaks, and diminished p53 DNA-damage response pathway activity.

Effect of pregnancy on hemangioblastoma development and progression in von Hippel-Lindau disease.

OBJECT: Prior cases suggest that pregnancy increases the development and progression of CNS hemangioblastomas and/or peritumoral cysts. To determine the effect of pregnancy on CNS hemangioblastomas and peritumoral cysts, the authors prospectively evaluated serial clinical and imaging findings in patients with von Hippel-Lindau (VHL) disease who became pregnant and compared findings during pregnancy to findings in the same patients when they were not pregnant as well as to findings from a cohort of VHL patients who did not become pregnant. METHODS: Female VHL disease patients enrolled in a prospective natural history study who were of reproductive age (16-35 years at study entrance) were included. Analysis of serial clinical and imaging findings was performed. RESULTS: Thirty-six consecutive female VHL disease patients harboring 177 hemangioblastomas were included (mean follow-up [± SD] 7.5 ± 2.3 years). Nine patients (25%) became pregnant (pregnancy cohort). The mean rates of development of new hemangioblastomas and peritumoral cysts in these women during pregnancy (0.4 ± 0.4 tumors/year; 0.1 ± 0.2 cysts/year) did not differ significantly (p > 0.05) from the mean rates in the same group during nonpregnant periods (0.3 ± 0.4 tumors/year; 0.1 ± -0.1 cysts/year) or from the rate in the 27 patients who did not become pregnant (the no-pregnancy cohort: 0.3 ± 0.5 tumors/year; 0.1 ± 0.2 cysts/year). Hemangioblastoma growth rates were similar (p > 0.05) during pregnancy (mean 29.8% ± 42.7% increase in volume per year) compared with during nonpregnant periods (41.4% ± 51.4%) in the pregnancy cohort and the no-pregnancy cohort (34.3% ± 55.3%). Peritumoral cyst growth rates during pregnancy (571.0% ± 887.4%) were similar (p > 0.05) to those of the no-pregnancy cohort (483.9% ± 493.9%), but the rates were significantly higher for women in the pregnancy cohort during nonpregnant periods (2373.6% ± 3392.9%; p < 0.05 for comparison with no-pregnancy cohort). There was no significant difference (p > 0.05) in the need for resection or the mean age at resection between the pregnancy (28% of hemangioblastomas in cohort; mean patient age at resection 30.2 ± 2.6 years) and no-pregnancy cohorts (19%; 32.3 ± 5.6 years). CONCLUSIONS: Pregnancy is not associated with increased hemangioblastoma or peritumoral cyst development or progression in patients with VHL disease.

Recency Effects in the Inferior Parietal Lobe during Verbal Recognition Memory.

The most recently encountered information is often most easily remembered in psychological tests of memory. Recent investigations of the neural basis of such "recency effects" have shown that activation in the lateral inferior parietal cortex (LIPC) tracks the recency of a probe item when subjects make recognition memory judgments. A key question regarding recency effects in the LIPC is whether they fundamentally reflect the storage (and strength) of information in memory, or whether such effects are a consequence of task difficulty or an upswing in resting state network activity. Using functional magnetic resonance imaging we show that recency effects in the LIPC are independent of the difficulty of recognition memory decisions, that they are not a by-product of an increase in resting state network activity, and that they appear to dissociate from regions known to be involved in verbal working memory maintenance. We conclude with a discussion of two alternative explanations - the memory strength and "expectancy" hypotheses, respectively - of the parietal lobe recency effect.