IMPORTANCE Clinical outcomes for glioblastoma remain poor. Treatment with immune checkpoint blockade has shown benefits in many cancer types. To our knowledge, data from a randomized phase 3 clinical trial evaluating a programmed death-1 (PD-1) inhibitor therapy for glioblastoma have not been reported.OBJECTIVE To determine whether single-agent PD-1 blockade with nivolumab improves survival in patients with recurrent glioblastoma compared with bevacizumab. DESIGN, SETTING, AND PARTICIPANTSIn this open-label, randomized, phase 3 clinical trial, 439 patients with glioblastoma at first recurrence following standard radiation and temozolomide therapy were enrolled, and 369 were randomized. Patients were enrolled between September 2014 and May 2015. The median follow-up was 9.5 months at data cutoff of January 20, 2017. The study included 57 multicenter, multinational clinical sites.INTERVENTIONS Patients were randomized 1:1 to nivolumab 3 mg/kg or bevacizumab 10 mg/kg every 2 weeks until confirmed disease progression, unacceptable toxic effects, or death. MAIN OUTCOMES AND MEASURES The primary end point was overall survival (OS).RESULTS A total of 369 patients were randomized to nivolumab (n = 184) or bevacizumab (n = 185). The MGMT promoter was methylated in 23.4% (43/184; nivolumab) and 22.7% (42/185; bevacizumab), unmethylated in 32.1% (59/184; nivolumab) and 36.2% (67/185; bevacizumab), and not reported in remaining patients. At median follow-up of 9.5 months, median OS (mOS) was comparable between groups: nivolumab, 9.8 months (95% CI, 8.2-11.8); bevacizumab, 10.0 months (95% CI, 9.0-11.8); HR, 1.04 (95% CI, 0.83-1.30); P = .76. The 12-month OS was 42% in both groups. The objective response rate was higher with bevacizumab (23.1%; 95% CI, 16.7%-30.5%) vs nivolumab (7.8%; 95% CI, 4.1%-13.3%). Grade 3/4 treatment-related adverse events (TRAEs) were similar between groups (nivolumab, 33/182 [18.1%]; bevacizumab, 25/165 [15.2%]), with no unexpected neurological TRAEs or deaths due to TRAEs. CONCLUSIONS AND RELEVANCEAlthough the primary end point was not met in this randomized clinical trial, mOS was comparable between nivolumab and bevacizumab in the overall patient population with recurrent glioblastoma. The safety profile of nivolumab in patients with glioblastoma was consistent with that in other tumor types.

Limiting dietary carbohydrates inhibits glioma growth in preclinical models. Therefore, the ERGO trial (NCT00575146) examined feasibility of a ketogenic diet in 20 patients with recurrent glioblastoma. Patients were put on a low-carbohydrate, ketogenic diet containing plant oils. Feasibility was the primary endpoint, secondary endpoints included the percentage of patients reaching urinary ketosis, progression-free survival (PFS) and overall survival. The effects of a ketogenic diet alone or in combination with bevacizumab was also explored in an orthotopic U87MG glioblastoma model in nude mice. Three patients (15%) discontinued the diet for poor tolerability. No serious adverse events attributed to the diet were observed. Urine ketosis was achieved at least once in 12 of 13 (92%) evaluable patients. One patient achieved a minor response and two patients had stable disease after 6 weeks. Median PFS of all patients was 5 (range, 3–13) weeks, median survival from enrollment was 32 weeks. The trial allowed to continue the diet beyond progression. Six of 7 (86%) patients treated with bevacizumab and diet experienced an objective response, and median PFS on bevacizumab was 20.1 (range, 12–124) weeks, for a PFS at 6 months of 43%. In the mouse glioma model, ketogenic diet alone had no effect on median survival, but increased that of bevacizumab-treated mice from 52 to 58 days (p<0.05). In conclusion, a ketogenic diet is feasible and safe but probably has no significant clinical activity when used as single agent in recurrent glioma. Further clinical trials are necessary to clarify whether calorie restriction or the combination with other therapeutic modalities, such as radiotherapy or anti-angiogenic treatments, could enhance the efficacy of the ketogenic diet.

No abstract

Combined immune checkpoint blockade (ICB) provides unprecedented efficacy gains in numerous cancer indications, with PD-1 inhibitor nivolumab plus CTLA-4 inhibitor ipilimumab in advanced melanoma as first-ever approved therapies for combined ICB. However, gains in efficacy must be balanced against a higher frequency and severity of adverse drug reactions (ADR). Because delays in diagnosis and management might result in symptom worsening and further complications, clinicians shall be well trained to identify ADR promptly and monitor patients adequately. This paper reviews safety data assessed by the European Medicines Agency for the anti-PD-1/CTLA-4 combination and provides a literature overview on published case reports for rare ADR with suspected potential underreporting. Incidences and kinetics of immune-related ADR are described. Recommendations for the evaluation and management of ADR are convened by an interdisciplinary expert panel focusing on rare but clinically important side effects arising from combined ICB. Pooled safety data from 1551 patients with advanced melanoma, treated either with 3mg/kg ipilimumab plus 1mg/kg nivolumab (N=407), or nivolumab alone (N=787), or ipilimumab alone (N=357) demonstrate that immune-related ADR occur more frequently for the combination, with a shorter time-to-onset, and tend to be more severe. The majority of events is reversible after systemic use of glucocorticoids, notably methylprednisolone or equivalents; in certain cases of long-lasting and refractory immune toxicities, non-steroidal immunosuppressants may be used, once ICB is interrupted or terminated. Combined ICB has considerable toxicities, therefore close monitoring and high experience in diagnosis and treatment of ADR is necessary.

Purpose: Rechallenge with temozolomide (TMZ) at first progression of glioblastoma after temozolomide chemoradiotherapy (TMZ/RT!TMZ) has been studied in retrospective and single-arm prospective studies, applying temozolomide continuously or using 7/14 or 21/28 days schedules. The DIRECTOR trial sought to show superiority of the 7/14 regimen.Experimental Design: Patients with glioblastoma at first progression after TMZ/RT!TMZ and at least two maintenance temozolomide cycles were randomized to Arm A [one week on (120 mg/m 2 per day)/one week off] or Arm B [3 weeks on (80 mg/m 2 per day)/one week off]. The primary endpoint was median timeto-treatment failure (TTF) defined as progression, premature temozolomide discontinuation for toxicity, or death from any cause. O 6 -methylguanine DNA methyltransferase (MGMT) promoter methylation was prospectively assessed by methylationspecific PCR.Results: Because of withdrawal of support, the trial was prematurely closed to accrual after 105 patients. There was a similar outcome in both arms for median TTF [A: 1.8 months; 95% confidence intervals (CI), 1.8-3.2 vs. B: 2.0 months; 95% CI, 1.8-3.5] and overall survival [A: 9.8 months (95% CI, 6.7-13.0) vs. B: 10.6 months (95% CI, 8.1-11.6)]. Median TTF in patients with MGMT-methylated tumors was 3.2 months (95% CI, 1.8-7.4) versus 1.8 months (95% CI, 1.8-2) in MGMT-unmethylated glioblastoma. Progression-free survival rates at 6 months (PFS-6) were 39.7% with versus 6.9% without MGMT promoter methylation.Conclusions: Temozolomide rechallenge is a treatment option for MGMT promoter-methylated recurrent glioblastoma. Alternative strategies need to be considered for patients with progressive glioblastoma without MGMT promoter methylation. Clin Cancer Res; 21(9); 2057-64. Ó2015 AACR.

BackgroundEven in the presence of oxygen, malignant cells often highly depend on glycolysis for energy generation, a phenomenon known as the Warburg effect. One strategy targeting this metabolic phenotype is glucose restriction by administration of a high-fat, low-carbohydrate (ketogenic) diet. Under these conditions, ketone bodies are generated serving as an important energy source at least for non-transformed cells.MethodsTo investigate whether a ketogenic diet might selectively impair energy metabolism in tumor cells, we characterized in vitro effects of the principle ketone body 3-hydroxybutyrate in rat hippocampal neurons and five glioma cell lines. In vivo, a non-calorie-restricted ketogenic diet was examined in an orthotopic xenograft glioma mouse model.ResultsThe ketone body metabolizing enzymes 3-hydroxybutyrate dehydrogenase 1 and 2 (BDH1 and 2), 3-oxoacid-CoA transferase 1 (OXCT1) and acetyl-CoA acetyltransferase 1 (ACAT1) were expressed at the mRNA and protein level in all glioma cell lines. However, no activation of the hypoxia-inducible factor-1α (HIF-1α) pathway was observed in glioma cells, consistent with the absence of substantial 3-hydroxybutyrate metabolism and subsequent accumulation of succinate. Further, 3-hydroxybutyrate rescued hippocampal neurons from glucose withdrawal-induced cell death but did not protect glioma cell lines. In hypoxia, mRNA expression of OXCT1, ACAT1, BDH1 and 2 was downregulated. In vivo, the ketogenic diet led to a robust increase of blood 3-hydroxybutyrate, but did not alter blood glucose levels or improve survival.ConclusionIn summary, glioma cells are incapable of compensating for glucose restriction by metabolizing ketone bodies in vitro, suggesting a potential disadvantage of tumor cells compared to normal cells under a carbohydrate-restricted ketogenic diet. Further investigations are necessary to identify co-treatment modalities, e.g. glycolysis inhibitors or antiangiogenic agents that efficiently target non-oxidative pathways.

Glioblastoma multiforme (GBM) is treated by surgical resection followed by radiochemotherapy. Bevacizumab is commonly deployed for anti‐angiogenic therapy of recurrent GBM; however, innate immune cells have been identified as instigators of resistance to bevacizumab treatment. We identified angiopoietin‐2 (Ang‐2) as a potential target in both naive and bevacizumab‐treated glioblastoma. Ang‐2 expression was absent in normal human brain endothelium, while the highest Ang‐2 levels were observed in bevacizumab‐treated GBM. In a murine GBM model, VEGF blockade resulted in endothelial upregulation of Ang‐2, whereas the combined inhibition of VEGF and Ang‐2 leads to extended survival, decreased vascular permeability, depletion of tumor‐associated macrophages, improved pericyte coverage, and increased numbers of intratumoral T lymphocytes. CD206+ (M2‐like) macrophages were identified as potential novel targets following anti‐angiogenic therapy. Our findings imply a novel role for endothelial cells in therapy resistance and identify endothelial cell/myeloid cell crosstalk mediated by Ang‐2 as a potential resistance mechanism. Therefore, combining VEGF blockade with inhibition of Ang‐2 may potentially overcome resistance to bevacizumab therapy.

Anti-angiogenic therapy in glioblastoma (GBM) has unfortunately not led to the anticipated improvement in patient prognosis. We here describe how human GBM adapts to bevacizumab treatment at the metabolic level. By performing 13C6-glucose metabolic flux analysis, we show for the first time that the tumors undergo metabolic re-programming toward anaerobic metabolism, thereby uncoupling glycolysis from oxidative phosphorylation. Following treatment, an increased influx of 13C6-glucose was observed into the tumors, concomitant to increased lactate levels and a reduction of metabolites associated with the tricarboxylic acid cycle. This was confirmed by increased expression of glycolytic enzymes including pyruvate dehydrogenase kinase in the treated tumors. Interestingly, l-glutamine levels were also reduced. These results were further confirmed by the assessment of in vivo metabolic data obtained by magnetic resonance spectroscopy and positron emission tomography. Moreover, bevacizumab led to a depletion in glutathione levels indicating that the treatment caused oxidative stress in the tumors. Confirming the metabolic flux results, immunohistochemical analysis showed an up-regulation of lactate dehydrogenase in the bevacizumab-treated tumor core as well as in single tumor cells infiltrating the brain, which may explain the increased invasion observed after bevacizumab treatment. These observations were further validated in a panel of eight human GBM patients in which paired biopsy samples were obtained before and after bevacizumab treatment. Importantly, we show that the GBM adaptation to bevacizumab therapy is not mediated by clonal selection mechanisms, but represents an adaptive response to therapy.Electronic supplementary materialThe online version of this article (doi:10.1007/s00401-014-1352-5) contains supplementary material, which is available to authorized users.