OMRT-13. Delivery of Ubidecarenone (BPM 31510) to mitochondria effectuates metabolic reprogramming and redox activated apoptosis in Glioblastoma

GBM is a highly metabolic cancer phenotype that confers sustained growth and evasion of cell death mechanism via mitochondrial dysregulation. Efforts to re-engage mitochondrial metabolism via anti-cancer therapeutics has not been successful. BPM 31510 is a CoQ10-lipid conjugate nanodispersion for delivery of CoQ10 preferentially to mitochondria of human cells. BPM has demonstrated anti-cancer effects across multiple cancers, without adversely affecting normal tissue. The anti-cancer mechanism of CoQ10 was elucidated by Interrogative Biology, a data-driven approach to understand disease biology, identify targets and biomarkers of disease. Specifically, oncogenic and corresponding non-disease normal cell-based models (e.g. breast, liver, prostate, kidney) were subjected to cancer specific perturbations (e.g. hypoxia, metabolic stress). Comprehensive multi-omic (genome, proteome, lipidome, metabolome) and functional endpoints data were profiled. A Bayesian artificial intelligence analytics was used to generate network models in a data driven manner to identify BPM 31510 mechanism (i.e. shift in oxygen and glucose utilization, increase in oxidative stress and apoptosis in cancer cells). BPM 31510 re-capitulated its anti-cancer effect in GBM models, including LN-229 xenograft and C6 glioma allograft, both as monotherapy and in combination with temozolomide (TMZ)/radiation. The platform generated network maps from longitudinal pharmacodynamic samples (20 samples/28 days) collected from GBM patient refractory to TMZ/radiation/bevacizumab (Phase 1, NCT03020602, Stanford) identified alterations in intermediary metabolism as drivers of Progression Free Survival (PFS) and Overall Survival (OS) in response to BPM 31510 treatment. The platform supports the ongoing Phase 2 trial of adjuvant BPM 31510 plus TMZ/radiation in newly diagnosed GBM patients and potential accelerated approval.

Abstract PO-096: Blocking the CXCL12/CXCR4 pathway both radiosensitizes brain metastases in mice and protects against radiation-induced cognitive dysfunction following whole brain irradiation in rats

We have previously shown using an antagonist of CXCR4 (plerixafor) with brain implanted tumors in mice(1)or by blocking CXCL12 by olaptesed pegol (ola-peg) with chemically-induced brain tumors in rats(2) that the radiation response of the tumors is markedly enhanced by blocking the CXCL12/CXCR4 pathway. In the present study we aimed to test whether a similar radiation enhancement is produced in mice with multiple brain metastases, and in addition, in preparation for a clinical trial of whole brain irradiation (WBI) with plerixafor, we sought to determine whether blocking the CXCL12/CXCR4 pathway would affect the cognitive dysfunction of rats given WBI. In the brain metastasis study we produced multiple brain metastases by injection of the luciferase transduced brain-tropic human breast triple negative cancer cell line MDA-MB-231 B3 into the internal carotid artery of nude mice. Adding the CXCL12 antagonist ola-peg after irradiation produced both a doubling of the regrowth delay (as monitored by bioluminescence imaging) and median survival time compared to irradiation alone. We also showed that similar to the brain implanted human glioblastoma studies that blocking the pathway prevented the radiation-induced influx of tumor associated macrophages (TAMs) into the brain metastases. In preliminary studies with cognitive dysfuction we gave adult Sprague-Dawley rats whole brain irradiation of 5, 10, 15 or 20 Gy and 2 months later measured their short term memory using the novel object recognition (NOR) test. We found that 20 Gy but not lower doses abrogated the rats’ ability to recognize novel objects, a key test of memory. Importantly we showed in a follow-up study that a 4-week infusion of plerixafor started immediately after irradiation (with the same dosing and schedule as our earlier tumor studies) not only did not affect memory in the controls and 15 Gy WBI groups but completely protected against memory loss in the 20 Gy group. In conclusion we showed that blocking the CXCL12/CXCR4 pathway not only potentiates the radiation response of a breast cancer brain metastasis model in mice but also protects against radiation-induced cognitive dysfunction in rats. This has led us to propose that blocking of this pathway which prevents the radiation-induced influx of TAMs into tumors and normal tissues is a novel strategy to enhance the therapeutic ratio of radiotherapy (3).

1. Kioi M, Vogel H, Schultz G, Hoffman RM, Harsh GR, Brown JM. Inhibition of vasculogenesis, but not angiogenesis, prevents the recurrence of glioblastoma after irradiation in mice. J Clin Invest 2010; 120:694-705. 2. Liu SC, Alomran R, Chernikova SB, Lartey F, Stafford J, Jang T, et al. Blockade of SDF-1 after irradiation inhibits tumor recurrences of autochthonous brain tumors in rats. Neuro Oncol 2014; 16:21-8. 3. Brown JM, Thomas R, Nagpal S, Recht L. Macrophage exclusion after radiation therapy (MERT): A new and effective way to increase the therapeutic ratio of radiotherapy. Radiother Oncol 2019; 144:159-64.

Citation Format: Martin Brown, Mehrdad Shamloo, Sophia Chernikova, Lawrence Recht. Blocking the CXCL12/CXCR4 pathway both radiosensitizes brain metastases in mice and protects against radiation-induced cognitive dysfunction following whole brain irradiation in rats [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PO-096.

BIMG-13. A NOVEL RADIOPHARMACEUTICAL ([18F]DASA-23) TO MONITOR PYRUVATE KINASE M2 INDUCED GLYCOLYTIC REPROGRAMMING IN GLIOBLASTOMA

BACKGROUND

Pyruvate kinase M2 (PKM2) catalyzes the final step in glycolysis, a key process of cancer metabolism. PKM2 is preferentially expressed by glioblastoma (GBM) cells with minimal expression in healthy brain, making it an important biomarker of cancer glycolytic re-programming. We describe the bench-to-bedside development, validation, and translation of a novel positron emission tomography (PET) tracer to study PKM2 in GBM. Specifically, we evaluated 1-((2-fluoro-6-[¹⁸F]fluorophenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine ([¹⁸F]DASA-23) in cell culture, mouse models of GBM, healthy human volunteers, and GBM patients.

METHODS

[¹⁸F]DASA-23 was synthesized with a molar activity of 100.47 ± 29.58 GBq/µmol and radiochemical purity >95%. We performed initial testing of [¹⁸F]DASA-23 in GBM cell culture and human GBM xenografts implanted orthotopically into mice. Next we produced [¹⁸F]DASA-23 under current Good Manufacturing Practices United States Food and Drug Administration (FDA) oversight, and evaluated it in healthy volunteers and a pilot cohort of patients with gliomas.

RESULTS

In mouse imaging studies, [¹⁸F]DASA-23 clearly delineated the U87 GBM from the surrounding healthy brain tissue and had a tumor-to-brain ratio (TBR) of 3.6 ± 0.5. In human volunteers, [¹⁸F]DASA-23 crossed the intact blood-brain barrier and was rapidly cleared. In GBM patients, [¹⁸F]DASA-23 successfully outlined tumors visible on contrast-enhanced magnetic resonance imaging (MRI). The uptake of [¹⁸F]DASA-23 was markedly elevated in GBMs compared to normal brain, and it was able to identify a metabolic non-responder within 1-week of treatment initiation.

CONCLUSION

We developed and translated [¹⁸F]DASA-23 as a promising new tracer that demonstrated the visualization of aberrantly expressed PKM2 for the first time in human subjects. These encouraging results warrant further clinical evaluation of [¹⁸F]DASA-23 to assess its utility for imaging therapy-induced normalization of aberrant cancer metabolism.

High levels of ubidecarenone (oxidized CoQ10) delivered using a drug-lipid conjugate nanodispersion (BPM31510) differentially affect redox status and growth in malignant glioma versus non-tumor cells

Metabolic reprogramming in cancer cells, vs. non-cancer cells, elevates levels of reactive oxygen species (ROS) leading to higher oxidative stress. The elevated ROS levels suggest a vulnerability to excess prooxidant loads leading to selective cell death, a therapeutically exploitable difference. Co-enzyme Q₁₀ (CoQ₁₀) an endogenous mitochondrial resident molecule, plays an important role in mitochondrial redox homeostasis, membrane integrity, and energy production. BPM31510 is a lipid-drug conjugate nanodispersion specifically formulated for delivery of supraphysiological concentrations of ubidecarenone (oxidized CoQ₁₀) to the cell and mitochondria, in both in vitro and in vivo model systems. In this study, we sought to investigate the therapeutic potential of ubidecarenone in the highly treatment-refractory glioblastoma. Rodent (C6) and human (U251) glioma cell lines, and non-tumor human astrocytes (HA) and rodent NIH3T3 fibroblast cell lines were utilized for experiments. Tumor cell lines exhibited a marked increase in sensitivity to ubidecarenone vs. non-tumor cell lines. Further, elevated mitochondrial superoxide production was noted in tumor cells vs. non-tumor cells hours before any changes in proliferation or the cell cycle could be detected. In vitro co-culture experiments show ubidecarenone differentially affecting tumor cells vs. non-tumor cells, resulting in an equilibrated culture. In vivo activity in a highly aggressive orthotopic C6 glioma model demonstrated a greater than 25% long-term survival rate. Based on these findings we conclude that high levels of ubidecarenone delivered using BPM31510 provide an effective therapeutic modality targeting cancer-specific modulation of redox mechanisms for anti-cancer effects.

Abstract 2968: BPM31510, a Coenzyme Q10 (CoQ10) containing lipid nanodispersion, enhances radiation effects to prolong survival in a rodent glioblastoma model

BPM31510 is a Coenzyme Q10 (CoQ10)-containing lipid nanodispersion in clinical development for the treatment of glioblastoma. Prior results demonstrate that high doses of CoQ10 delivered via BPM31510 differentially increases oxidative stress in glioblastoma relative to non-tumor cells in vitro and extends long-term survival (LTS) in an in vivo glioblastoma model. Since a primary consequences of tumor irradiation is induction of oxidative stress, we hypothesized that BPM31510 treatment would result in an enhanced radiation response and influence survival outcomes.1 x 106 luciferase labeled C6 cells were implanted into the right striatum of Sprague Dawley rats. 4 days post-implantation, rats were randomized into one of four groups: (i) Saline injection ip bid; (ii) BPM31510 50 mg/kg ip bid to continue up to 35 days; (iii) 12 Gy radiotherapy (RT) to be administered on Day 8 post-implant with saline injection; and (iv) BPM31510 + RT. Tumor-bearing rats were monitored until death or Day 50. Log rank survival analysis indicated a marked enhancement of median survival with the addition of BPM31510 to RT. While neither RT nor BPM31510 enhanced median survival relative to saline, the combination was markedly more effective (median survival of 17, 19, 24 and >50 days for saline, BPM31510, RT and combination, respectively, p < 0.001). This was also reflected in increase in frequency of LTS, which was over 70% (11 of 14 rats) in the combination group (p < 0.01 compared to control). BPM31510 significantly enhanced the therapeutic efficacy of radiation in this model of glioblastoma. Effects on median survival and an enhancement of LTS with combination treatment were observed. While the mechanistic underpinnings are under investigation, the low toxicity profile of BPM31510 and its potential protective effects on normal cells may offer a unique strategy with which to enhance radiation.

Citation Format: Jiaxin Sun, Milton Merchant, Anne R. Diers, Shiva Kazerounian, Stephane Gesta, Niven R. Narain, Rangaprasad Sarangarajan, Seema Nagpal, Lawrence Recht. BPM31510, a Coenzyme Q10 (CoQ10) containing lipid nanodispersion, enhances radiation effects to prolong survival in a rodent glioblastoma model [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2968.

Evaluating Surgical Resection Extent and Adjuvant Therapy in the Management of Gliosarcoma

Introduction: Gliosarcomas are clinically aggressive tumors, histologically distinct from glioblastoma. Data regarding the impact of extent of resection and post-operative adjuvant therapy on gliosarcoma outcomes are limited.

Methods: Patients with histologically confirmed gliosarcoma diagnosed between 1999 and 2019 were identified. Clinical, molecular, and radiographic data were assembled based on historical records. Comparisons of categorical variables used Pearson's Chi-square and Fisher's exact test while continuous values were compared using the Wilcoxon signed-rank test. Survival comparisons were assessed using Kaplan-Meier statistics and Cox regressions.

Results: Seventy-one gliosarcoma patients were identified. Secondary gliosarcoma was not associated with worse survival when compared to recurrent primary gliosarcoma (median survival 9.8 [3.8 to 21.0] months vs. 7.6 [1.0 to 35.7], p = 0.7493). On multivariable analysis, receipt of temozolomide (HR = 0.02, 95% CI 0.001–0.21) and achievement of gross total resection (GTR; HR = 0.13, 95% CI 0.02–0.77) were independently prognostic for improved progression-free survival (PFS) while only receipt of temozolomide was independently associated with extended overall survival (OS) (HR = 0.03, 95% CI 0.001–0.89). In patients receiving surgical resection followed by radiotherapy and concomitant temozolomide, achievement of GTR was significantly associated with improved PFS (median 32.97 [7.1–79.6] months vs. 5.45 [1.8–26.3], p = 0.0092) and OS (median 56.73 months [7.8–104.5] vs. 14.83 [3.8 to 29.1], p = 0.0252).

Conclusion: Multimodal therapy is associated with improved survival in gliosarcoma. Even in patients receiving aggressive post-operative multimodal management, total surgical removal of macroscopic disease remains important for optimal outcomes.

Reversed metabolic reprogramming as a measure of cancer treatment efficacy in rat C6 glioma model

BACKGROUND

Metabolism in tumor shifts from oxidative phosphorylation to inefficient glycolysis resulting in overproduction of lactate (Warburg effect), and cancers may be effectively treated if this imbalance were corrected. The aim of this longitudinal study of glioblastoma in a rat model was to determine whether the ratio of lactate (surrogate marker for glycolysis) to bicarbonate (for oxidative phosphorylation), as measured via in vivo magnetic resonance imaging of hyperpolarized 13C-labeled pyruvate accurately predicts survival.

METHODS

C6 Glioma implanted male Wistar rats (N = 26) were treated with an anti-vascular endothelial growth factor antibody B20.4.1.1 in a preliminary study to assess the efficacy of the drug. In a subsequent longitudinal survival study, magnetic resonance spectroscopic imaging (MRSI) was used to estimate [1-13C]Lactate and [1-13C]Bicarbonate in tumor and contralateral normal appearing brain of glioma implanted rats (N = 13) after injection of hyperpolarized [1-13C]Pyruvate at baseline and 48 hours post-treatment with B20.4.1.1.

RESULTS

A survival of ~25% of B20.4.1.1 treated rats was noted in the preliminary study. In the longitudinal imaging experiment, changes in 13C Lactate, 13C Bicarbonate and tumor size measured at baseline and 48 hours post-treatment did not correlate with survival. 13C Lactate to 13C Bicarbonate ratio increased in all the 6 animals that succumbed to the tumor whereas the ratio decreased in 6 of the 7 animals that survived past the 70-day observation period.

CONCLUSIONS

13C Lactate to 13C Bicarbonate ratio (Lac/Bic) at 48 hours post-treatment is highly predictive of survival (p = 0.003). These results suggest a potential role for the 13C Lac/Bic ratio serving as a valuable measure of tumor metabolism and predicting therapeutic response.

NIMG-36. EVALUATION OF [18F]DASA-23 FOR NON-INVASIVE MEASUREMENT OF ABERRANTLY EXPRESSED PYRUVATE KINASE M2 IN GLIOMA: FIRST-IN-HUMAN STUDY

OBJECTIVES

We developed 1-((2-fluoro-6-(fluoro-[18F])phenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine ([18F]DASA-23) as a novel radiopharmaceutical to measure pyruvate kinase M2 levels by positron emission tomography (PET). PKM2 catalyzes the final step in glycolysis, the key process of tumor metabolism. PKM2 is preferentially expressed by glioblastoma (GBM) cells with minimal expression in the healthy brain, making it an important biomarker of cancer glycolytic re-programming. Here, we report the first evaluation of [18F]DASA-23 in human healthy volunteers and subjects with low-grade (LGG) and high-grade glioma (HGG).

METHODS

[18F]DASA-23 was synthesized under GMP conditions. Brain [18F]DASA-23 PET/MRI scans (3T) were performed in human healthy volunteers (n=5) and subjects with LGG (n=3) and HGG (n=2). The PET imaging duration was 60 min and standardized uptake value (SUV) calculations were performed on the 30–60 min summed images. The maximum SUV in the tumor (TumorSUVmax) and contralateral white matter (WMSUVmax) were calculated.

RESULTS

[18F]DASA-23 specific activity was 2961±873 mCi/µmol (n=10) with radiochemical purity >95%, injected mass of 1.8±0.7 mcg, and dose of 0.3±0.02 mcg per kg body weight. In healthy volunteers, [18F]DASA-23 crossed the intact blood-brain barrier and was rapidly cleared through the bladder and also showed uptake in the gallbladder, liver, and intestines over time. [18F]DASA-23 was found to be intact in plasma up to 10 min post-injection and 75% intact at 30 min post-injection. In subjects with glioma, TumorSUVmax was significantly greater in HGG (2.2±0.4, n=2) compared to LGG (0.8±0.3m n=3), p=0.02. In this early human series, the normalized ratio of TumorSUVmax/WMSUVmax was not significantly different between subjects with HGG (2.0±0.6) and LGG (1.0±0.4), p=0.1.

CONCLUSION

[18F]DASA-23 is a promising new imaging agent for the non-invasive delineation of LGG and HGG based on aberrantly expressed PKM2. An ongoing study is evaluating the utility of this agent in additional patients with intracranial malignancies (NCT03539731).

ACTR-59. A PHASE 1 STUDY OF BPM31510 PLUS VITAMIN K IN SUBJECTS WITH HIGH-GRADE GLIOMA THAT HAS RECURRED ON A BEVACIZUMAB-CONTAINING REGIMEN

BACKGROUND

High-grade gliomas (HGG) are characterized by dysregulated metabolism, utilizing glycolysis for energy production to support unrestricted growth. BPM 31510, an ubidecarenone (coenzyme Q10) containing lipid nanodispersion, causes a switch in cancer energy sourcing from glycolysis towards mitochondrial oxidative phosphorylation in vitro, reversing the Warburg effect and suggesting potential as an anti-tumor agent. The current study is a phase I study of BPM31510 + vitamin K in GB with tumor growth after bevacizumab (BEV).

METHODS

This is an open-label phase I study of BPM31510 continuous infusion with weekly vitamin K (10mg IM) in HGG patients using an mTPI design, starting at 110mg/kg, allowing for a single dose de-escalation and 2 dose-escalations. Patients had received first-line ChemoRadiation and were in recurrence following a BEV containing regimen.

RESULTS

9 eligible and evaluable patients completed the 28 day DLT period. 8 patients had primary GB, 1 had anaplastic astrocytoma with confirmed pathologic transformation to GB. Median age was 55 years (27–67) and median KPS 70 (60–90) at enrollment. 4 patients were treated at the highest dose 171mg/kg, where there was a single DLT: Grade 3 AST & ALT. The most common grade 1–2 AEs possibly, probably or definitely related to drug were elevated AST, rash, and fatigue, each occurring in 3 patients. Median OS for 9 eligible/evaluable patients was 128 days (95% CI: 48–209) while PFS was 34 days (CI of mean 8.9). 3 patients are currently alive; 2 patients have survived >1 year. PK/PD data are being processed and will be presented.

CONCLUSION

This study confirms that BPM 31510 + vitamin K is safe and feasible in treatment-refractory HGG patients. Though this study demonstrates safety at 171mg/kg, the proposed dose for future studies in GB, based on additional pre-clinical and non-GB clinical data is 88mg/kg.

A proteomic clock for malignant gliomas: The role of the environment in tumorigenesis at the presymptomatic stage

Malignant gliomas remain incurable with a poor prognosis despite of aggressive treatment. We have been studying the development of brain tumors in a glioma rat model, where rats develop brain tumors after prenatal exposure to ethylnitrosourea (ENU), and there is a sizable interval between when the first pathological changes are noted and tumors become detectable with MRI. Our aim to define a molecular timeline through proteomic profiling of the cerebrospinal fluid (CSF) such that brain tumor commitment can be revealed earlier than at the presymptomatic stage. A comparative proteomic approach was applied to profile CSF collected serially either before, at and after the time MRI becomes positive. Elastic net (EN) based models were developed to infer the timeline of normal or tumor development respectively, mirroring a chronology of precisely timed, “clocked”, adaptations. These CSF changes were later quantified by longitudinal entropy analyses of the EN predictive metric. False discovery rates (FDR) were computed to control the expected proportion of the EN models that are due to multiple hypothesis testing. Our ENU rat brain tumor dating EN model indicated that protein content in CSF is programmed even before tumor MRI detection. The findings of the precisely timed CSF tumor microenvironment changes at presymptomatic stages, deviation from the normal development timeline, may provide the groundwork for the understanding of adaptation of the brain environment in tumorigenesis to devise effective brain tumor management strategies.

Perfusion MRI-Based Fractional Tumor Burden Differentiates between Tumor and Treatment Effect in Recurrent Glioblastomas and Informs Clinical Decision-Making

BACKGROUND AND PURPOSE

Fractional tumor burden better correlates with histologic tumor volume fraction in treated glioblastoma than other perfusion metrics such as relative CBV. We defined fractional tumor burden classes with low and high blood volume to distinguish tumor from treatment effect and to determine whether fractional tumor burden can inform treatment-related decision-making.

MATERIALS AND METHODS

Forty-seven patients with high-grade gliomas (primarily glioblastoma) with recurrent contrast-enhancing lesions on DSC-MR imaging were retrospectively evaluated after surgical sampling. Histopathologic examination defined treatment effect versus tumor. Normalized relative CBV thresholds of 1.0 and 1.75 were used to define low, intermediate, and high fractional tumor burden classes in each histopathologically defined group. Performance was assessed with an area under the receiver operating characteristic curve. Consensus agreement among physician raters reporting hypothetic changes in treatment-related decisions based on fractional tumor burden was compared with actual real-time treatment decisions.

RESULTS

Mean lower fractional tumor burden, high fractional tumor burden, and relative CBV of the contrast-enhancing volume were significantly different between treatment effect and tumor (P = .002, P < .001, and P < .001), with tumor having significantly higher fractional tumor burden and relative CBV and lower fractional tumor burden. No significance was found with intermediate fractional tumor burden. Performance of the area under the receiver operating characteristic curve was the following: high fractional tumor burden, 0.85; low fractional tumor burden, 0.7; and relative CBV, 0.81. In comparing treatment decisions, there were disagreements in 7% of tumor and 44% of treatment effect cases; in the latter, all disagreements were in cases with scattered atypical cells.

CONCLUSIONS

High fractional tumor burden and low fractional tumor burden define fractions of the contrast-enhancing lesion volume with high and low blood volume, respectively, and can differentiate treatment effect from tumor in recurrent glioblastomas. Fractional tumor burden maps can also help to inform clinical decision-making.

Abstract 3608: BPM31510 exploits differential redox vulnerabilities between normal and glioblastoma cells to mediate its anti-cancer effect

Glioblastoma is an aggressive cancer, the proliferative capacity of which is correlated with glycolytic metabolism. BPM31510 is a novel formulation for delivery of supraphysiological levels of ubidecarenone to the mitochondria, enabling cancer specific metabolic switches. It is being studied in Phase I clinical trials versus a number of tumors, including glioma. Here, the effects of ubidecarenone on viability and redox homeostasis of glioma and non-tumorigenic cells was assessed using in vitro monoculture and coculture systems and an in vivo preclinical model. BPM31510 administration (50 mg/kg bid i.p., beginning 4-8 days post-inoculation) resulted in over a 20% long term survival rate in C6 tumor-bearing rats. We next compared BPM31510 effects in vitro between glioma lines (rat C6, human U251) and murine NIH3T3 fibroblasts, as a stromal control. In monocultures, decreased growth was observed in glioma lines and NIH3T3 with increasing BPM31510 doses; however, glioma lines were 2-fold more sensitive to BPM31510 compared to NIH3T3 cells (IC50 glioma lines: 230 µM vs IC50 NIH3T3: &gt;460 µM). To investigate the differential sensitivity to BPM31510, a coculture system was developed by coincubating 2 x 105 C6-GFP labeled cells and NIH3T3 cells. After 6 days of coculture, the percentage of C6 relative to NIH3T3 cells was lowest at doses of BPM31510 between 115 µM and 230 µM, evidence of greater sensitivity to BPM31510-induced cytotoxicity in the C6 glioma cells than the non-tumorigenic component. At higher doses, differential effects on cell viability were less apparent. The level of superoxide, a central reactive oxygen species important in redox homeostasis, was also assessed using Mitosox in cocultures. At a BPM31510 dose which resulted in maximal differential viability between C6 and NIH3T3 cells (230 μM), the maximal differential superoxide level was likewise greatest. The basal differential in Mitosox signal was 9-fold between C6 and NIH3T3 cells, and it increased to over 50-fold upon treatment with BPM31510 (230 μM), implying that BPM31510 exploits differential redox vulnerabilities between C6 and NIH3T3 to mediate its anti-cancer activity. At high doses of BPM31510, differential effects on superoxide levels were less apparent. In summary, BPM31510 has marked anti-cancer activity in rats implanted with C6 glioma, and its differential effects on the viability of normal and transformed cells are associated with maximal differences in BPM31510-induced superoxide production. Together, these data suggest that differential redox vulnerabilities between tumorigenic and non-tumorigenic cells may underpin the anti-cancer activity of BPM31510, and identification of in vivo correlates of redox indices may represent an avenue to improved measurement of anti-cancer efficacy as well as define patient populations responsive to BPM31510.

Citation Format: Jiaxin Sun, Seema Nagpal, Chirag Patel, Milton Merchant, Tiachang Jang, Anne R. Diers, Shiva Kazerounian, Stephane Gesta, Niven R. Narain, Rangaprasad Sarangarajan, Lawrence Recht. BPM31510 exploits differential redox vulnerabilities between normal and glioblastoma cells to mediate its anti-cancer effect [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3608.

Abstract 873: BPM 31510, a clinical stage metabolic modulator, demonstrates therapeutic efficacy in glioblastoma models of temozolomide chemo-sensitive and resistance by targeting mitochondrial function

BPM31510 is a metabolic modulating agent composed of a parenteral nanodispersion of ubidecarenone which is currently in clinical studies for glioblastoma. Glioblastoma is a highly metabolic and aggressive malignancy with limited treatment options and dismal median survival. Temozolomide (TMZ) as a first line treatment option, however, 90% of recurrent gliomas acquire TMZ chemoresistance. Recently, acquisition to TMZ resistance has been correlated to alterations in mitochondrial metabolism. Thus, in the present study we sought to investigate whether BPM31510 could elicit anti-cancer activity in TMZ naïve and TMZ-chemoresistant glioma models. In vitro, in a 2D model BPM31510 treatment demonstrated anti-cancer activity in a panel of glioma cell lines (rat C6 and human U251-MG and U87-MG), and this effect was translatable in spheroidal 3D cultures. Importantly, in an aggressive rat C6 orthotopic glioma model, treatment with BPM31510 (50mg/kg/day, b.i.d) starting between 4 and 8 days post-implantation resulted in a 32% cure rate compared to 0% in controls (P &lt; 0.001, Fisher's exact test), demonstrating an improved survival (P &lt; 0.01, log rank survival), despite producing a minimal change in median survival (13 vs. 12 days). A marked increase in caspase3 staining was observed in tumors from BPM31510 treated animals compared to controls assessed at a similar time point post-tumor implantation, suggesting a strong apoptotic effect of this agent in vivo. Next, BPM31510 was examined in a cellular model of acquired TMZ resistance (TMZ-R) generated by exposing parental (chemosensitive naïve) U251-MG and U87-MG cells to increasing concentrations of TMZ for 9-12 months. Similar to parental cells, BPM31510 displayed anti-cancer activity in both TMZ-R cell models, as decreased cell viability and an increase in the percentage of apoptotic cells was observed upon BPM31510 treatment. Consistent with prior studies, compared to parental cells, TMZ-R cells demonstrated metabolic rewiring characterized by increases in mitochondrial function parameters and decreased extracellular acidification rate, indicative of glycolytic flux. Regardless of chemosensitivity, BPM31510 decreased mitochondrial substrate oxidation (e.g., succinate, glycerol-3-phosphate) at doses which induce cell death. Concomitantly, increases in the reactive oxygen species production were observed with BPM 31510 treatment in both parental and TMZ-R cell lines. Together, these data define a link between regulation of mitochondrial function and the anti-cancer activity of BPM31510 in both TMZ chemo-sensitive and resistant glioblastoma models, demonstrating a distinct approach in targeting mitochondrial metabolism for the treatment of this clinically intractable disease.

Citation Format: Tulin Dadali, Shreya Kulkarni, Ryan Ng, Pallavi Awate, Saie Mogre, Anne R. Diers, Taichang Jang, Milton Merchant, Jiaxin Sun, Stephane Gesta, Khampaseuth Thapa, Seema Nagpal, Lawrence Recht, Niven R. Narain, Rangaprasad Sarangarajan. BPM 31510, a clinical stage metabolic modulator, demonstrates therapeutic efficacy in glioblastoma models of temozolomide chemo-sensitive and resistance by targeting mitochondrial function [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 873.

Phase I Study of MEDI3617, a Selective Angiopoietin-2 Inhibitor Alone and Combined with Carboplatin/Paclitaxel, Paclitaxel, or Bevacizumab for Advanced Solid Tumors

Purpose: This first-in-human study aimed to determine the MTD and safety of MEDI3617, a selective anti-angiopoietin-2 (Ang2) mAb, alone and combined with bevacizumab or cytotoxic chemotherapy.Patients and Methods: This phase I/Ib, multicenter, open-label, dose-escalation and dose-expansion study evaluated patients with advanced solid tumors. Patients received intravenous MEDI3617 as monotherapy [5-1,500 mg every 3 weeks (Q3W)] or with bevacizumab every 2 weeks (Q2W) or Q3W, weekly paclitaxel, or carboplatin plus paclitaxel Q3W. Dose expansions included a monotherapy cohort in platinum-resistant ovarian cancer and a bevacizumab combination cohort in bevacizumab-refractory malignant glioma. Safety/tolerability, pharmacokinetics, pharmacodynamics, and clinical activity were assessed.Results: We enrolled 116 patients. No formal MTD was identified (monotherapy or combination therapy). MEDI3617 demonstrated linear pharmacokinetics and maximal accumulation of peripheral Ang2 binding at doses above 300 mg Q3W. MEDI3617 monotherapy safety profile was acceptable, except in advanced ovarian cancer [prolonged grade 3 edema-associated adverse events (AE) occurred]. Otherwise, MEDI3617 combined with chemotherapy or bevacizumab was well tolerated. The AE profiles of MEDI3617 and bevacizumab were largely non-overlapping. Overall response rates in ovarian cancer and glioma monotherapy dose-expansion arms were 6% and 0%, respectively.Conclusions: Recommended MEDI3617 monotherapy dosage is 1,500 mg Q3W or 1,000 mg Q2W, except in ovarian cancer. Although peripheral edema has occurred with other Ang2 inhibitors, the severity and duration seen here in ovarian cancer potentially identifies a new, clinically significant safety signal for this class of agents. On the basis of limited clinical activity, MEDI3617 development was discontinued. Clin Cancer Res; 24(12); 2749-57. ©2018 AACR.

A Metabolic Therapy for Malignant Glioma Requires a Clinical Measure

Cancers are "reprogrammed" to use a much higher rate of glycolysis (GLY) relative to oxidative phosphorylation (OXPHOS), even in the presence of adequate amounts of oxygenation. Originally identified by Nobel Laureate Otto Warburg, this hallmark of cancer has recently been termed metabolic reprogramming and represents a way for the cancer tissue to divert carbon skeletons to produce biomass. Understanding the mechanisms that underlie this metabolic shift should lead to better strategies for cancer treatments. Malignant gliomas, cancers that are very resistant to conventional treatments, are highly glycolytic and seem particularly suited to approaches that can subvert this phenotype.

Abstract 1598: Single agent NKTR-214, a biased IL2 pathway agonist, increases immune cell infiltrates in brain tumors and prolongs survival in rodent (rattus) glioblastoma (GBM)

Background: Immunotherapy is an attractive option for brain tumor therapy if a robust infiltrative T cell response can be elicited in the tumor. NKTR-214 is a CD122-biased cytokine agonist conjugated with multiple releasable chains of polyethylene glycol and designed to provide sustained signaling through the heterodimeric IL-2 receptor pathway (IL-2Rβγ) to preferentially activate and expand effector CD8+ T and NK cells over Tregs. To assess the potential activity of single agent NKTR-214 in GBM, we used an orthotopic rat glioblastoma survival model.

Methods:NKTR-214 was administered at 0.1 or 0.3 mg/kg q2w iv to Sprague-Dawley rats starting 2 or 7 days (D2, D7) post (p)-implantation of 106 C6 glioma cells into the right striatum. The model requires euthanasia by ~D14 due to tumor burden. Brain tumors were characterized by magnetic resonance (MR) and immunohistochemistry (IHC) for infiltration of CD4+ and CD8+ T cells and for retention of PEG polymer in brain tumor.

Results: Compared to rats receiving vehicle (n = 15), survival was significantly prolonged after NKTR-214 treatment (n = 43, mean 17.2 vs. 10.0 days (P &lt; 0.001) with 15% of rats across all groups alive and tumor-free at Day 50 when the study was terminated. Both doses were equally effective and well tolerated. Surprisingly, treated rats bearing large MR-detectable D7 tumors survived significantly longer compared to rats bearing microscopic D2 tumors (6/21 or ~30% versus 0/21 or 0% respectively at D50, mean 23.1 vs. 12 days, P &lt; 0.004). Concordantly, CD8+ T cells in D7 tumors were significantly increased after NKTR-214 therapy compared to vehicle and D2 tumors, while CD4+ remained low with no significant difference between groups. PEG polymer was detected in the tumor at least 72 hours p-injection.

Conclusions: NKTR-214 is well tolerated, prolongs survival and induces immunological activity in the brain when administered to rats harboring orthotopic GBM. While there was no significant dose dependence, a marked increase in survival was observed when larger D7 tumors were treated with NKTR-214 compared to microscopic D2 tumors, associated with increased intratumoral CD8+ T cells. Levels of CD4+ were unchanged, consistent with the mechanism of CD-122 biased activation of the IL2 pathway. While requiring further study, it is intriguing that the increased sensitivity of larger tumors also corresponds to onset of angiogenesis and rapid tumor growth in this model. NKTR-214 is currently being evaluated in an outpatient Phase 1 / 2 clinical trial for the treatment of solid tumors. The results presented suggest a potential role for NKTR-214 in the treatment of patients afflicted with GBM.

Citation Format: Lawrence Recht, Seema Nagpal, Taichang Jang, Milton Merchant, Irene Choi, Ute Hoch, Deborah Charych. Single agent NKTR-214, a biased IL2 pathway agonist, increases immune cell infiltrates in brain tumors and prolongs survival in rodent (rattus) glioblastoma (GBM) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1598. doi:10.1158/1538-7445.AM2017-1598

Optimizing bevacizumab dosing in glioblastoma: less is more

Compared to traditional chemotherapies, where dose limiting toxicities represent the maximum possible dose, monoclonal antibody therapies are used at doses well below maximum tolerated dose. However, there has been little effort to ascertain whether there is a submaximal dose at which the efficacy/complication ratio is maximized. Thus, despite the general practice of using Bevacizumab (BEV) at dosages of 10 mg/kg every other week for glioma patients, there has not been much prior work examining whether the relatively high complication rates reported with this agent can be decreased by lowering the dose without impairing efficacy. We assessed charts from 80 patients who received BEV for glioblastoma to survey the incidence of complications relative to BEV dose. All patients were treated with standard upfront chemoradiation. The toxicity was graded based on the NCI CTCAE, version 4.03. The rate of BEV serious related adverse events was 12.5% (n = 10/80). There were no serious adverse events (≥grade 3) when the administered dose was (<3 mg/kg/week), compared to a 21% incidence in those who received higher doses (≥3 mg/kg/week) (P < 0.01). Importantly, the three patient deaths attributable to BEV administration occurred in patients receiving higher doses. Patients who received lower doses also had a better survival rate, although this did not reach statistical significance [median OS 39 for low dose group vs. 17.3 for high dose group (P = 0.07)]. Lower rates of serious BEV related toxicities are noted when lower dosages are used without diminishing positive clinical impact. Further work aimed at optimizing BEV dosage is justified.

The Promise of Targeting Macrophages in Cancer Therapy

Cancer therapy has developed around the concept of killing, or stopping the growth of, the cancer cells. Molecularly targeted therapy is the modern expression of this paradigm. Increasingly, however, the realization that the cancer has co-opted the normal cells of the stroma for its own survival has led to the concept that the tumor microenvironment (TME) could be targeted for effective therapy. In this review, we outline the importance of tumor-associated macrophages (TAM), a major component of the TME, in the response of tumors to cancer therapy. We discuss the normal role of macrophages in wound healing, the major phenotypes of TAMs, and their role in blunting the efficacy of cancer treatment by radiation and anticancer drugs, both by promoting tumor angiogenesis and by suppressing antitumor immunity. Finally, we review the many preclinical studies that have shown that the response of tumors to irradiation and anticancer drugs can be improved, sometimes markedly so, by depleting TAMs from tumors or by suppressing their polarization from an M1 to an M2 phenotype. The data clearly support the validity of clinical testing of combining targeting TAMs with conventional therapy. Clin Cancer Res; 23(13); 3241-50. ©2017 AACR.

Randomized, Double-Blind, Placebo-Controlled, Multicenter Phase II Study of Onartuzumab Plus Bevacizumab Versus Placebo Plus Bevacizumab in Patients With Recurrent Glioblastoma: Efficacy, Safety, and Hepatocyte Growth Factor and O6-Methylguanine–DNA Methyltransferase Biomarker Analyses

Purpose

Bevacizumab regimens are approved for the treatment of recurrent glioblastoma in many countries. Aberrant mesenchymal-epithelial transition factor (MET) expression has been reported in glioblastoma and may contribute to bevacizumab resistance. The phase II study GO27819 investigated the monovalent MET inhibitor onartuzumab plus bevacizumab (Ona + Bev) versus placebo plus bevacizumab (Pla + Bev) in recurrent glioblastoma.

Methods

At first recurrence after chemoradiation, bevacizumab-naïve patients with glioblastoma were randomly assigned 1:1 to receive Ona (15 mg/kg, once every 3 weeks) + Bev (15 mg/kg, once every 3 weeks) or Pla + Bev until disease progression. The primary end point was progression-free survival by response assessment in neuro-oncology criteria. Secondary end points were overall survival, objective response rate, duration of response, and safety. Exploratory biomarker analyses correlated efficacy with expression levels of MET ligand hepatocyte growth factor, O6-methylguanine–DNA methyltransferase promoter methylation, and glioblastoma subtype.

Results

Among 129 patients enrolled (Ona + Bev, n = 64; Pla + Bev, n = 65), baseline characteristics were balanced. The median progression-free survival was 3.9 months for Ona + Bev versus 2.9 months for Pla + Bev (hazard ratio, 1.06; 95% CI, 0.72 to 1.56; P = .7444). The median overall survival was 8.8 months for Ona + Bev and 12.6 months for Pla + Bev (hazard ratio, 1.45; 95% CI, 0.88 to 2.37; P = .1389). Grade ≥ 3 adverse events were reported in 38.5% of patients who received Ona + Bev and 35.9% of patients who received Pla + Bev. Exploratory biomarker analyses suggested that patients with high expression of hepatocyte growth factor or unmethylated O6-methylguanine–DNA methyltransferase may benefit from Ona + Bev.

Conclusion

There was no evidence of further clinical benefit with the addition of onartuzumab to bevacizumab compared with bevacizumab plus placebo in unselected patients with recurrent glioblastoma in this phase II study; however, further investigation into biomarker subgroups is warranted.

SDF-1 Blockade Enhances Anti-VEGF Therapy of Glioblastoma and Can Be Monitored by MRI

Despite the approval of antiangiogenic therapy for glioblastoma multiforme (GBM) patients, survival benefits are still limited. One of the resistance mechanisms for antiangiogenic therapy is the induction of hypoxia and subsequent recruitment of macrophages by stromal-derived factor (SDF)-1α (CXCL-12). In this study, we tested whether olaptesed pegol (OLA-PEG, NOX-A12), a novel SDF-1α inhibitor, could reverse the recruitment of macrophages and potentiate the antitumor effect of anti–vascular endothelial growth factor (VEGF) therapy. We also tested whether magnetic resonance imaging (MRI) with ferumoxytol as a contrast agent could provide early information on macrophage blockade. Orthotopic human G12 glioblastomas in nude mice and rat C6 glioblastomas were employed as the animal models. These were treated with bevacizumab or B-20, both anti-VEGF antibodies. Rats were MR imaged with ferumoxytol for macrophage detection. Tumor hypoxia and SDF-1α expression were elevated by VEGF blockade. Adding OLA-PEG to bevacizumab or B-20 significantly prolonged the survival of rodents bearing intracranial GBM compared with anti-VEGF therapy alone. Intratumoral CD68+ tumor associated macrophages (TAMs) were increased by VEGF blockade, but the combination of OLA-PEG + VEGF blockade markedly lowered TAM levels compared with VEGF blockade alone. MRI with ferumoxytol as a contrast agent noninvasively demonstrated macrophage reduction in OLA-PEG + anti-VEGF–treated rats compared with VEGF blockade alone. In conclusion, inhibition of SDF-1 with OLA-PEG inhibited the recruitment of TAMs by VEGF blockage and potentiated its antitumor efficacy in GBM. Noninvasive MRI with ferumoxytol as a contrast agent provides early information on the effect of OLA-PEG in reducing TAMs.

Central Nervous System Cancers, Version 1.2015

The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Central Nervous System (CNS) Cancers provide interdisciplinary recommendations for managing adult CNS cancers. Primary and metastatic brain tumors are a heterogeneous group of neoplasms with varied outcomes and management strategies. These NCCN Guidelines Insights summarize the NCCN CNS Cancers Panel's discussion and highlight notable changes in the 2015 update. This article outlines the data and provides insight into panel decisions regarding adjuvant radiation and chemotherapy treatment options for high-risk newly diagnosed low-grade gliomas and glioblastomas. Additionally, it describes the panel's assessment of new data and the ongoing debate regarding the use of alternating electric field therapy for high-grade gliomas.

Response of metastatic glioma to vemurafenib

Extraneural metastatic disease of glioma is rare and poses unique therapeutic challenges. Increasingly, the ability to sequence genetic alterations in tumors has allowed for the identification of common oncogenic signatures such as the activating BRAF^V600E mutation and may be useful in therapeutic decision making. We report two patients with widespread aggressive gliomas whose tumors were found to express the BRAF^V600E mutation and then responded robustly albeit transiently when exposed to vemurafenib. Although both patients succumbed to their disease, our results suggest that targeting BRAF might be appropriate for patients with aggressive gliomas that express this mutation.

Central nervous system cancers, version 2.2014. Featured updates to the NCCN Guidelines

The NCCN Guidelines for Central Nervous System Cancers provide multidisciplinary recommendations for the clinical management of patients with cancers of the central nervous system. These NCCN Guidelines Insights highlight recent updates regarding the management of metastatic brain tumors using radiation therapy. Use of stereotactic radiosurgery (SRS) is no longer limited to patients with 3 or fewer lesions, because data suggest that total disease burden, rather than number of lesions, is predictive of survival benefits associated with the technique. SRS is increasingly becoming an integral part of management of patients with controlled, low-volume brain metastases.

Cerebrospinal fluid protein dynamic driver network: At the crossroads of brain tumorigenesis

To get a better understanding of the ongoing in situ environmental changes preceding the brain tumorigenesis, we assessed cerebrospinal fluid (CSF) proteome profile changes in a glioma rat model in which brain tumor invariably developed after a single in utero exposure to the neurocarcinogen ethylnitrosourea (ENU). Computationally, the CSF proteome profile dynamics during the tumorigenesis can be modeled as non-smooth or even abrupt state changes. Such brain tumor environment transition analysis, correlating the CSF composition changes with the development of early cellular hyperplasia, can reveal the pathogenesis process at network level during a time before the image detection of the tumors. In our controlled rat model study, matched ENU- and saline-exposed rats' CSF proteomics changes were quantified at approximately 30, 60, 90, 120, 150 days of age (P30, P60, P90, P120, P150). We applied our transition-based network entropy (TNE) method to compute the CSF proteome changes in the ENU rat model and test the hypothesis of the critical transition state prior to impending hyperplasia. Our analysis identified a dynamic driver network (DDN) of CSF proteins related with the emerging tumorigenesis progressing from the non-hyperplasia state. The DDN associated leading network CSF proteins can allow the early detection of such dynamics before the catastrophic shift to the clear clinical landmarks in gliomas. Future characterization of the critical transition state (P60) during the brain tumor progression may reveal the underlying pathophysiology to device novel therapeutics preventing tumor formation. More detailed method and information are accessible through our website at http://translationalmedicine.stanford.edu.

Glioblastoma Multiforme Recurrence: An Exploratory Study of (18)F FPPRGD2 PET/CT

PURPOSE

To prospectively evaluate fluorine 18 ((18)F) 2-fluoropropionyl-labeled PEGylated dimeric arginine-glycine-aspartic acid (RGD) peptide (PEG3-E[c{RGDyk}]2) (FPPRGD2) positron emission tomography (PET) in patients with glioblastoma multiforme (GBM).

MATERIALS AND METHODS

The institutional review board approved this HIPAA-compliant protocol. Written informed consent was obtained from each patient. (18)F FPPRGD2 uptake was measured semiquantitatively in the form of maximum standardized uptake values (SUV(max)) and uptake volumes before and after treatment with bevacizumab. Vital signs and laboratory results were collected before, during, and after the examinations. A nonparametric version of multivariate analysis of variance was used to assess safety outcome measures simultaneously across time points. A paired two-sample t test was performed to compare SUV(max).

RESULTS

A total of 17 participants (eight men, nine women; age range, 25-65 years) were enrolled prospectively. (18)F FPPRGD2 PET/computed tomography (CT), (18)F fluorodeoxyglucose (FDG) PET/CT, and brain magnetic resonance (MR) imaging were performed within 3 weeks, prior to the start of bevacizumab therapy. In eight of the 17 patients (47%), (18)F FPPRGD2 PET/CT was repeated 1 week after the start of bevacizumab therapy; six patients (35%) underwent (18)F FPPRGD2 PET/CT a third time 6 weeks after starting bevacizumab therapy. There were no changes in vital signs, electrocardiographic findings, or laboratory values that qualified as adverse events. One patient (6%) had recurrent GBM identified only on (18)F FPPRGD2 PET images, and subsequent MR images enabled confirmation of recurrence. Of the 17 patients, 14 (82%) had recurrent GBM identified on (18)F FPPRGD2 PET and brain MR images, while (18)F FDG PET enabled identification of recurrence in 13 (76%) patients. Two patients (12%) had no recurrent GBM.

CONCLUSION

(18)F FPPRGD2 is a safe PET radiopharmaceutical that has increased uptake in GBM lesions. Larger cohorts are required to confirm these preliminary findings.

Cerebral Blood Flow Changes in Glioblastoma Patients Undergoing Bevacizumab Treatment Are Seen in Both Tumor and Normal Brain

Bevacizumab (BEV) is increasingly used to treat recurrent glioblastoma (GBM) with some reported improvement in neurocognitive function despite potential neurotoxicities. We examined the effects of BEV on cerebral blood flow (CBF) within recurrent GBM tumor and in the contralateral middle cerebral artery (MCA) territory.Post-chemoradiation patients with histologically confirmed GBM were treated with BEV and underwent routine, serial tumor imaging with additional pseudocontinuous arterial spin labeling (pcASL) following informed consent. Circular regions-of-interest were placed on pcASL images directly over the recurrent tumor and in the contralateral MCA territory. CBF changes before and during BEV treatment were evaluated in tumor and normal tissue. Linear mixed models were used to assess statistical significance.Fifty-three pcASL studies in 18 patients were acquired. Evaluation yielded lower mean tumoral CBF during BEV treatment compared with pre-treatment (45 ± 27 vs. 65 ± 27 ml/100 g/min, p = 0.002), and in the contralateral MCA territory during, compared with pre-BEV treatment (35 ± 8.4 vs. 41 ± 8.4 ml/100 g/min, p = 0.03). The decrease in mean CBF tended to be greater in the tumoral region than in the contralateral MCA, though the difference did not reach statistical significance (31% vs. 13%; p = 0.082).

CONCLUSIONS

BEV administration results in statistically significant global CBF decrease with a potentially preferential decrease in tumor perfusion compared with normal brain tissue.

γ-Glutamyl transferase 7 is a novel regulator of glioblastoma growth

Background

Glioblastoma (GBM) is the most malignant primary brain tumor in adults, with a median survival time of one and a half years. Traditional treatments, including radiation, chemotherapy, and surgery, are not curative, making it imperative to find more effective treatments for this lethal disease. γ-Glutamyl transferase (GGT) is a family of enzymes that was shown to control crucial redox-sensitive functions and to regulate the balance between proliferation and apoptosis. GGT7 is a novel GGT family member that is highly expressed in brain and was previously shown to have decreased expression in gliomas. Since other members of the GGT family were found to be altered in a variety of cancers, we hypothesized that GGT7 could regulate GBM growth and formation.

Methods

To determine if GGT7 is involved in GBM tumorigenesis, we modulated GGT7 expression in two GBM cell lines (U87-MG and U138) and monitored changes in tumorigenicity in vitro and in vivo.

Results

We demonstrated for the first time that GBM patients with low GGT7 expression had a worse prognosis and that 87% (7/8) of primary GBM tissue samples showed a 2-fold decrease in GGT7 expression compared to normal brain samples. Exogenous expression of GGT7 resulted in a 2- to 3-fold reduction in proliferation and anchorage-independent growth under minimal growth conditions (1% serum). Decreasing GGT7 expression using either short interfering RNA or short hairpin RNA consistently increased proliferation 1.5- to 2-fold. In addition, intracranial injections of U87-MG cells with reduced GGT7 expression increased tumor growth in mice approximately 2-fold, and decreased mouse survival. To elucidate the mechanism by which GGT7 regulates GBM growth, we analyzed reactive oxygen species (ROS) levels in GBM cells with modulated GGT7 expression. We found that enhanced GGT7 expression reduced ROS levels by 11-33%.

Conclusion

Our study demonstrates that GGT7 is a novel player in GBM growth and that GGT7 can play a critical role in tumorigenesis by regulating anti-oxidative damage. Loss of GGT7 may increase the cellular ROS levels, inducing GBM occurrence and growth. Our findings suggest that GGT7 can be a promising biomarker and a potential therapeutic target for GBM.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1232-y) contains supplementary material, which is available to authorized users.

Supratentorial low-grade diffuse astrocytoma: medical management

Diffuse astrocytomas (DAs) represent less than 10% of all gliomas. They are diffusely infiltrating World Health Organization (WHO) grade II neoplasms that have a median survival in the range of 5-7 years, generally with a terminal phase in which they undergo malignant transformation to glioblastoma (GBM). The goals of treatment in addition to prolonging survival are therefore to prevent progression and malignant transformation, as well as optimally managing symptoms, primarily tumor-associated epilepsy. Available data suggest that the course of this disease is only minimally impacted by adjuvant therapies and that there does not seem to be much difference in terms of outcome of whether patients are treated in the adjuvant setting with irradiation or chemotherapy. We review the experience with chemotherapy as a treatment modality and offer some guidelines for its usage and discuss medical management of arising symptoms.

Central nervous system cancers

Primary and metastatic tumors of the central nervous system are a heterogeneous group of neoplasms with varied outcomes and management strategies. Recently, improved survival observed in 2 randomized clinical trials established combined chemotherapy and radiation as the new standard for treating patients with pure or mixed anaplastic oligodendroglioma harboring the 1p/19q codeletion. For metastatic disease, increasing evidence supports the efficacy of stereotactic radiosurgery in treating patients with multiple metastatic lesions but low overall tumor volume. These guidelines provide recommendations on the diagnosis and management of this group of diseases based on clinical evidence and panel consensus. This version includes expert advice on the management of low-grade infiltrative astrocytomas, oligodendrogliomas, anaplastic gliomas, glioblastomas, medulloblastomas, supratentorial primitive neuroectodermal tumors, and brain metastases. The full online version, available at NCCN. org, contains recommendations on additional subtypes.

Inhibition of CXCR7 extends survival following irradiation of brain tumours in mice and rats

Background:

In experimental models of glioblastoma multiforme (GBM), irradiation (IR) induces local expression of the chemokine CXCL12/SDF-1, which promotes tumour recurrence. The role of CXCR7, the high-affinity receptor for CXCL12, in the tumour's response to IR has not been addressed.

Methods:

We tested CXCR7 inhibitors for their effects on tumour growth and/or animal survival post IR in three rodent GBM models. We used immunohistochemistry to determine where CXCR7 protein is expressed in the tumours and in human GBM samples. We used neurosphere formation assays with human GBM xenografts to determine whether CXCR7 is required for cancer stem cell (CSC) activity in vitro.

Results:

CXCR7 was detected on tumour cells and/or tumour-associated vasculature in the rodent models and in human GBM. In human GBM, CXCR7 expression increased with glioma grade and was spatially associated with CXCL12 and CXCL11/I-TAC. In the rodent GBM models, pharmacological inhibition of CXCR7 post IR caused tumour regression, blocked tumour recurrence, and/or substantially prolonged survival. CXCR7 expression levels on human GBM xenograft cells correlated with neurosphere-forming activity, and a CXCR7 inhibitor blocked sphere formation by sorted CSCs.

Conclusions:

These results indicate that CXCR7 inhibitors could block GBM tumour recurrence after IR, perhaps by interfering with CSCs.

Blockade of SDF-1 after irradiation inhibits tumor recurrences of autochthonous brain tumors in rats

Background

Tumor irradiation blocks local angiogenesis, forcing any recurrent tumor to form new vessels from circulating cells. We have previously demonstrated that the post-irradiation recurrence of human glioblastomas in the brains of nude mice can be delayed or prevented by inhibiting circulating blood vessel–forming cells by blocking the interaction of CXCR4 with its ligand stromal cell-derived factor (SDF)–1 (CXCL12). In the present study we test this strategy by directly neutralizing SDF-1 in a clinically relevant model using autochthonous brain tumors in immune competent hosts.

Methods

We used NOX-A12, an l-enantiomeric RNA oligonucleotide that binds and inhibits SDF-1 with high affinity. We tested the effect of this inhibitor on the response to irradiation of brain tumors in rat induced by n-ethyl-N-nitrosourea.

Results

Rats treated in utero with N-ethyl-N-nitrosourea began to die of brain tumors from approximately 120 days of age. We delivered a single dose of whole brain irradiation (20 Gy) on day 115 of age, began treatment with NOX-A12 immediately following irradiation, and continued with either 5 or 20 mg/kg for 4 or 8 weeks, doses and times equivalent to well-tolerated human exposures. We found a marked prolongation of rat life span that was dependent on both drug dose and duration of treatment. In addition we treated tumors only when they were visible by MRI and demonstrated complete regression of the tumors that was not achieved by irradiation alone or with the addition of temozolomide.

Conclusions

Inhibition of SDF-1 following tumor irradiation is a powerful way of improving tumor response of glioblastoma multiforme.

Simultaneous perfusion and permeability measurements using combined spin- and gradient-echo MRI

The purpose of this study was to estimate magnetic resonance imaging-based brain perfusion parameters from combined multiecho spin-echo and gradient-echo acquisitions, to correct them for T₁₋, T₂₋, and T₂₋*-related contrast agent (CA) extravasation effects, and to simultaneously determine vascular permeability. Perfusion data were acquired using a combined multiecho spin- and gradient-echo (SAGE) echo-planar imaging sequence, which was corrected for CA extravasation effects using pharmacokinetic modeling. The presented method was validated in simulations and brain tumor patients, and compared with uncorrected single-echo and multiecho data. In the presence of CA extravasation, uncorrected single-echo data resulted in underestimated CA concentrations, leading to underestimated single-echo cerebral blood volume (CBV) and mean transit time (MTT). In contrast, uncorrected multiecho data resulted in overestimations of CA concentrations, CBV, and MTT. The correction of CA extravasation effects resulted in CBV and MTT estimates that were more consistent with the underlying tissue characteristics. Spin-echo perfusion data showed reduced large-vessel blooming effects, facilitating better distinction between increased CBV due to active tumor progression and elevated CBV due to the presence of cortical vessels in tumor proximity. Furthermore, extracted permeability parameters were in good agreement with elevated T1-weighted postcontrast signal values.

Steroid-sparing effect of corticorelin acetate in peritumoral cerebral edema is associated with improvement in steroid-induced myopathy

PURPOSE

To compare the safety and efficacy of corticorelin acetate (CrA) and placebo in patients with malignant brain tumors requiring chronic administration of dexamethasone (DEX) to control the signs and symptoms of peritumoral brain edema (PBE).

PATIENTS AND METHODS

Prospective, randomized, double-blind study of 200 patients with PBE on a stable dose of DEX. Initially, DEX dose was decreased by 50% over a 2-week period and then held at this level for 3 weeks. The primary end point was the proportion of patients who responded to treatment-patients who achieved a ≥ 50% DEX reduction from baseline and achieved stable or improved neurologic examination score and Karnofsky performance score at week 2, and then continued to respond at week 5.

RESULTS

One hundred patients received subcutaneous injections of 1 mg twice per day of CrA and 100 patients received placebo for the duration of the study period. Although results did not attain statistical significance (at the P < .05 level), a clinically important difference in the proportion of responders between the CrA group (57.0%) and the placebo group (46.0%; P = .12) was observed. In addition, the maximum percent reduction in DEX dose achieved during the double-blind 12-week study was significantly greater in the CrA group (62.7%) than in placebo group (51.4%; P < .001). Patients receiving CrA demonstrated an improvement in myopathy and were less likely to develop signs of Cushing syndrome.

CONCLUSION

CrA enables a reduction in steroid requirement for patients with PBE and is associated with a reduction in the incidence and severity of common steroid adverse effects, including myopathy.

Advances in the management of glioblastoma: the role of temozolomide and MGMT testing

Glioblastoma (GB) is one of the most lethal forms of cancer, with an invasive growth pattern that requires the use of adjuvant therapies, including chemotherapy and radiation, to prolong survival. Temozolomide (TMZ) is an oral chemotherapy with a limited side effect profile that has become the standard of care in GB treatment. While TMZ has made an impact on survival, tumor recurrence and TMZ resistance remain major challenges. Molecular markers, such as O6-methylguanine-DNA methyltransferase methylation status, can be helpful in predicting tumor response to TMZ, and therefore guides clinical decision making. This review will discuss the epidemiology and possible genetic underpinnings of GB, how TMZ became the standard of care for GB patients, the pharmacology of TMZ, the practical aspects of using TMZ in clinic, and how molecular diagnostics – particularly the use of O6-methylguanine-DNA methyltransferase status – affect clinical management.

Thrombin-cleaved fragments of osteopontin are overexpressed in malignant glial tumors and provide a molecular niche with survival advantage

Osteopontin (OPN), which is highly expressed in malignant glioblastoma (GBM), possesses inflammatory activity modulated by proteolytic cleavage by thrombin and plasma carboxypeptidase B2 (CPB2) at a highly conserved cleavage site. Full-length OPN (OPN-FL) was elevated in cerebrospinal fluid (CSF) samples from all cancer patients compared with noncancer patients. However, thrombin-cleaved OPN (OPN-R) and thrombin/CPB2-double-cleaved OPN (OPN-L) levels were markedly increased in GBM and non-GBM gliomas compared with systemic cancer and noncancer patients. Cleaved OPN constituted ∼23 and ∼31% of the total OPN in the GBM and non-GBM CSF samples, respectively. OPN-R was also elevated in GBM tissues. Thrombin-antithrombin levels were highly correlated with cleaved OPN, but not OPN-FL, suggesting that the cleaved OPN fragments resulted from increased thrombin and CPB2 in this extracellular compartment. Levels of VEGF and CCL4 were increased in CSF of GBM and correlated with the levels of cleaved OPN. GBM cell lines were more adherent to OPN-R and OPN-L than OPN-FL. Adhesion to OPN altered gene expression, in particular genes involved with cellular processes, cell cycle regulation, death, and inflammation. OPN and its cleaved forms promoted motility of U-87 MG cells and conferred resistance to apoptosis. Although functional mutation of the RGD motif in OPN largely abolished these functions, OPN(RAA)-R regained significant cell binding and signaling function, suggesting that the SVVYGLR motif in OPN-R may substitute for the RGD motif if the latter becomes inaccessible. OPN cleavage contributes to GBM development by allowing more cells to bind in niches where they acquire anti-apoptotic properties.