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The blood–brain barrier (BBB) excludes the vast majority of cancer therapeutics from normal brain. However, the importance of the BBB in limiting drug delivery and efficacy is controversial in high-grade brain tumors, such as glioblastoma (GBM). The accumulation of normally brain impenetrant radiographic contrast material in essentially all GBM has popularized a belief that the BBB is uniformly disrupted in all GBM patients so that consideration of drug distribution across the BBB is not relevant in designing therapies for GBM. However, contrary to this view, overwhelming clinical evidence demonstrates that there is also a clinically significant tumor burden with an intact BBB in all GBM, and there is little doubt that drugs with poor BBB permeability do not provide therapeutically effective drug exposures to this fraction of tumor cells. This review provides an overview of the clinical literature to support a central hypothesis: that all GBM patients have tumor regions with an intact BBB, and cure for GBM will only be possible if these regions of tumor are adequately treated.

BACKGROUND: Vorinostat, a histone deacetylase (HDAC) inhibitor, has shown radiosensitizing properties in preclinical studies. This open-label, single-arm trial evaluated the maximum tolerated dose (MTD; phase I) and efficacy (phase II) of vorinostat combined with standard chemoradiation in newly diagnosed glioblastoma. METHODS: Patients received oral vorinostat (300 or 400 mg/day) on days 1–5 weekly during temozolomide chemoradiation. Following a 4- to 6-week rest, patients received up to 12 cycles of standard adjuvant temozolomide and vorinostat (400 mg/day) on days 1–7 and 15–21 of each 28-day cycle. Association between vorinostat response signatures and progression-free survival (PFS) and overall survival (OS) was assessed based on RNA sequencing of baseline tumor tissue. RESULTS: Phase I and phase II enrolled 15 and 107 patients, respectively. The combination therapy MTD was vorinostat 300 mg/day and temozolomide 75 mg/m(2)/day. Dose-limiting toxicities were grade 4 neutropenia and thrombocytopenia and grade 3 aspartate aminotransferase elevation, hyperglycemia, fatigue, and wound dehiscence. The primary efficacy endpoint in the phase II cohort, OS rate at 15 months, was 55.1% (median OS 16.1 mo), and consequently, the study did not meet its efficacy objective. Most common treatment-related grade 3/4 toxicities in the phase II component were lymphopenia (32.7%), thrombocytopenia (28.0%), and neutropenia (21.5%). RNA expression profiling of baseline tumors (N = 76) demonstrated that vorinostat resistance (sig-79) and sensitivity (sig-139) signatures had a reverse and positive association with OS/PFS, respectively. CONCLUSIONS: Vorinostat combined with standard chemoradiation had acceptable tolerability in newly diagnosed glioblastoma. Although the primary efficacy endpoint was not met, vorinostat sensitivity and resistance signatures could facilitate patient selection in future trials.

Purpose Whole brain radiation therapy (WBRT) remains a commonly used cancer treatment, although controversy exists regarding the optimal dose/fractionation to optimize intracranial tumor control and minimize resultant cognitive deficits. Methods and Materials NCCTG N107C [Alliance]/CEC.3 randomized 194 patients with brain metastases to either stereotactic radiosurgery alone or WBRT after surgical resection. Among the 92 patients receiving WBRT, sites predetermined the dose/fractionation that would be used for all patients treated at that site (either 30 Gy in 10 fractions or 37.5 Gy in 15 fractions). Analyses were performed using Kaplan-Meier estimates, log rank tests, and Fisher’s exact tests. Results Among 92 patients treated with surgical resection and adjuvant WBRT, 49 were treated with 30 Gy in 10 fractions (53%), and 43 were treated with 37.5 Gy in 15 fractions (47%). Baseline characteristics, including cognitive testing, were well balanced between groups with the exception of primary tumor type (lung cancer histology was more frequent with protracted WBRT: 72% vs 45%, P = .01), and 93% of patients completed the full course of WBRT. A more protracted WBRT dose regimen (37.5 Gy in 15 fractions) did not significantly affect time to cognitive failure (hazard ratio [HR], 0.9; 95% confidence interval [CI], 0.6-1.39; P = .66), surgical bed control (HR, 0.52 [95% CI, 0.22-1.25], P = .14), intracranial tumor control (HR, 0.56 [95% CI, 0.28-1.12], P = .09), or overall survival (HR, 0.72 [95% CI, 0.45-1.16], P = .18). Although there was no reported radionecrosis, there is a statistically significant increase in the risk of at least 1 grade ≥3 adverse event with 37.5 Gy in 15 fractions versus 30 Gy in 10 fractions (54% vs 31%, respectively, P = .03). Conclusions This post hoc analysis does not demonstrate that protracted WBRT courses reduce the risk of cognitive deficit, improve tumor control in the hypoxic surgical cavity, or otherwise improve the therapeutic ratio. Adverse events were significantly higher with the lengthened course of WBRT. For patients with brain metastases where WBRT is recommended, shorter course hypofractionated regimens remain the current standard of care.

Background: Src signaling is markedly upregulated in patients with invasive glioblastoma (GBM) after the administration of bevacizumab. The Src family kinase inhibitor dasatinib has been found to effectively block bevacizumab-induced glioma invasion in preclinical models, which led to the hypothesis that combining bevacizumab with dasatinib could increase bevacizumab efficacy in patients with recurrent GBM. Methods: After the completion of the phase 1 component, the phase 2 trial (ClinicalTrials.gov identifier NCT00892177) randomized patients with recurrent GBM 2:1 to receive 100mg of oral dasatinib twice daily (arm A) or placebo (arm B) on days 1 to 14 of each 14-day cycle combined with 10mg/kg of intravenous bevacizumab on day 1 of each 14-day cycle. The primary endpoint was 6-month progression-free survival (PFS6). Results: In the 121 evaluable patients, the PFS6 rate was numerically, but not statistically, higher in arm A versus arm B (28.9% [95% CI, 19.5%-40.0%] vs 18.4% [95% CI, 7.7%-34.4%]; P=.22). Similarly, there was no significant difference in the median overall survival noted between the treatment arms (7.3months and 7.7months, respectively; P=.93). The objective response rate was 15.7% in arm A and 26.3% in arm B (P=.52), but with a significantly longer duration in patients treated on arm A (16.3months vs 2months). The incidence of grade ≥3 toxicity was comparable between treatment arms, with hematologic toxicities occurring more frequently in arm A versus arm B (15.7% vs 7.9%) (adverse events were assessed as per the National Cancer Institute Common Terminology Criteria for Adverse Events [version 4.0]). Correlative tissue analysis demonstrated an association between pSRC/LYN signaling in patient tumors and outcome. Conclusions: Despite upregulation of Src signaling in patients with GBM, the combination of bevacizumab with dasatinib did not appear to significantly improve the outcomes of patients with recurrent GBM compared with bevacizumab alone.

Purpose: To evaluate the pharmacokinetics and efficacy of imatinib in patients with recurrent oligodendroglial tumors. Methods: Patients with progressive WHO grade II-III recurrent tumors after prior RT and chemotherapy were eligible. A phase I dose-escalation study was conducted for patients on enzyme-inducing anticonvulsants (EIAC). A phase II study for non-EIAC patients utilized a fixed dose of 600mg/D. Primary efficacy endpoint was 6-month progression-free survival (PFS6). A 2-stage design was utilized, with 90% power to detect PFS6 increase from 25 to 45%. Results: In the Phase I, maximum tolerated dose was not reached at 1200mg/D. For phase II patients, overall PFS6 was 33% and median PFS 4.0months (95% CI 2.1, 5.7). Median overall survival (OS) was longer in imatinib-treated patients compared with controls (16.6 vs. 8.0months; HR = 0.64, 95% CI 0.41,1.0, p = 0.049), and longer in patients with 1p/19q-codeleted tumors (19.2 vs. 6.2months, HR = 0.43, 95% CI 0.21,0.89, p = 0.019). Confirmed response rate was 3.9% (PR = 1; REGR = 1), with stable disease observed in 52.9%. At 600mg/D, mean steady-state imatinib plasma concentration was 2513ng/ml (95% CI 1831,3195). Grade 3–4 adverse events (hematologic, fatigue, GI, hypophosphatemia, or hemorrhage) occurred in 61%. Conclusions: Although adequate plasma levels were achieved, the observed PFS6 of 33% did not reach our pre-defined threshold for success. Although OS was longer in imatinib-treated patients than controls, this finding would require forward validation in a larger cohort. Imatinib might show greater activity in a population enriched for PDGF-dependent pathway activation in tumor tissue.

BACKGROUND: Mitogen-activated protein kinase (MAPK) activation and mammalian target of rapamycin (mTOR)-dependent signaling are hallmarks of glioblastoma. In the current study, the authors conducted a phase 1/2 study of sorafenib (an inhibitor of Raf kinase and vascular endothelial growth factor receptor 2 [VEGFR-2]) and the mTOR inhibitor temsirolimus in patients with recurrent glioblastoma. METHODS: Patients with recurrent glioblastoma who developed disease progression after surgery or radiotherapy plus temozolomide and with ≤2 prior chemotherapy regimens were eligible. The phase 1 endpoint was the maximum tolerated dose (MTD), using a cohorts-of-3 design. The 2-stage phase 2 study included separate arms for VEGF inhibitor (VEGFi)–naive patients and patients who progressed after prior VEGFi. RESULTS: The MTD was sorafenib at a dose of 200 mg twice daily and temsirolimus at a dose of 20 mg weekly. In the first 41 evaluable patients who were treated at the phase 2 dose, there were 7 who were free of disease progression at 6 months (progression-free survival at 6 months [PFS6]) in the VEGFi-naive group (17.1%); this finding met the prestudy threshold of success. In the prior VEGFi group, only 4 of the first 41 evaluable patients treated at the phase 2 dose achieved PFS6 (9.8%), and this did not meet the prestudy threshold for success. The median PFS for the 2 groups was 2.6 months and 1.9 months, respectively. The median overall survival for the 2 groups was 6.3 months and 3.9 months, respectively. At least 1 adverse event of grade ≥3 was observed in 75.5% of the VEGFi-naive patients and in 73.9% of the prior VEGFi patients. CONCLUSIONS: The limited activity of sorafenib and temsirolimus at the dose and schedule used in the current study was observed with considerable toxicity of grade ≥3. Significant dose reductions that were required in this treatment combination compared with tolerated single-agent doses may have contributed to the lack of efficacy. Cancer 2018;124:1455-63. © 2018 American Cancer Society.

Background Pilocytic astrocytoma is a rare tumor in adults. This report is of a prospective clinical trial with long-term follow-up. Methods Between 1986 and 1994, 20 eligible adults with supratentorial pilocytic astrocytomas were enrolled in a prospective intergroup trial of radiotherapy (RT) after biopsy (3 patients) or observation after gross (11 patients) or subtotal (6 patients) resection. Results At the time of analysis (median follow-up, 20.8 years), 2 patients (10%) have died and 18 patients (90%) are alive. Neurologic and cognitive function were stable or improved over time for the majority of patients. No toxic effects of treatment or malignant transformations have been recorded at last follow-up. For the entire cohort the 20-year time to progression and overall survival rates are 95% and 90% respectively. The cause of death (2.2 and 16.1 years after enrollment) in both patients was unrelated to tumor although both were biopsy-only patients. One subtotally resected tumor progressed 1 month after enrollment requiring P32 injection into an enlarging cyst. Because of further progression this patient required RT 18 months later. This patient is alive without evidence of progression 18 years after RT. Conclusion The long-term follow-up results of this prospective trial confirm that adults with pilocytic astrocytomas have a favorable prognosis with regard to survival and neurologic function. Close observation is recommended for adults with pilocytic astrocytomas, reserving RT for salvage, as the majority remain stable after gross or subtotal resection and no adjuvant therapy.