Phase II study of metronomic chemotherapy with bevacizumab for recurrent glioblastoma after progression on bevacizumab therapy

Re-Irradiation Plus Pembrolizumab: A Phase II Study for Patients with Recurrent Glioblastoma

PURPOSE

Radiotherapy may enhance antitumor immune responses by several mechanisms, including induction of immunogenic cell death. We performed a phase 2 study of pembrolizumab with re-irradiation in patients with recurrent glioblastoma.

PATIENTS AND METHODS

Sixty patients with recurrent glioblastoma received pembrolizumab with re-irradiation alone (cohort A, bevacizumab-naïve; n = 30) or with bevacizumab continuation (cohort B, n = 30). Dual primary endpoints, including the overall response rate and overall survival (OS) at either 12 (OS-12; cohort A) or 6 months (OS-6; cohort B), were assessed per cohort relative to historic benchmarks. Paired paraffin-embedded formalin-fixed tumor samples were assessed for immunologic biomarkers by IHC using digital quantification and co-detection-by-indexing (CODEX).

RESULTS

Study therapy was well tolerated, with most toxicities being grade ≤3. For cohort B, the primary endpoint of OS-6 was achieved (57%); however, survival was not improved for cohort A patients. The overall response rate was 3.3% and 6.7% for cohorts A and B, respectively. CODEX analysis of paired tumor samples from five patients revealed an increase of activated T cells in the tumor microenvironment after study therapy.

CONCLUSIONS

Compared with historic controls, re-irradiation plus pembrolizumab seemed to improve survival among bevacizumab-refractory patients but not among bevacizumab-naïve patients. CODEX revealed evidence of intratumoral infiltration of activated immune effector cells. A randomized, properly controlled trial of PD-1 blockade plus re-irradiation is warranted to further evaluate this regimen for bevacizumab-refractory patients, but alternative approaches are needed for bevacizumab-naïve patients.

Identifying the best treatment choice for relapsing/refractory glioblastoma: a systematic review with multiple Bayesian network meta-analyses

BACKGROUND

Glioblastoma is a highly aggressive primary central nervous system tumor characterized by poor outcomes. In case of relapse or progression to adjuvant chemotherapy, there is no univocal preferred regimen for relapsing glioblastoma.

METHODS

We conducted a systematic review and Bayesian trial-level network meta-analyses (NMA) to identify the regimens associated with the best outcomes. The primary endpoint was overall survival (OS). Secondary endpoints were progression-free survival (PFS) and overall response rates (ORR). We estimated separate treatment rankings based on the surface under the cumulative ranking curve values. Only phase II/III prospective comparative trials were included.

RESULTS

Twenty-four studies (3733 patients and 27 different therapies) were ultimately included. Twenty-three different regimens were compared for OS, 21 for PFS, and 26 for ORR. When taking lomustine as a common comparator, only regorafenib was likely to be significantly superior in terms of OS (hazard ratio: 0.50, 95% credible interval: 0.33-0.75). Regorafenib was significantly superior to other 16 (69.6%) regimens, including NovoTTF-100A, bevacizumab monotherapy, and several bevacizumab-based combinations. Regarding PFS and ORR, no treatment was clearly superior to the others.

CONCLUSIONS

This NMA supports regorafenib as one of the best available options for relapsing/refractory glioblastoma. Lomustine, NovoTTF-100A, and bevacizumab emerge as other viable alternative regimens. However, evidence on regorafenib is controversial at best. Moreover, most studies were underpowered, with varying inclusion criteria and primary endpoints, and no longer adapted to the most recent glioblastoma classification. A paradigmatic change in clinical trials' design for relapsing/refractory glioblastoma and more effective treatments are urgently required.

Nanoparticle-mediated metronomic chemotherapy in cancer: A paradigm of precision and persistence

Current methods of cancer therapy have demonstrated enormous potential in tumor inhibition. However, a high dosage regimen of chemotherapy results in various complications which affect the normal body cells. Tumor cells also develop resistance against the prescribed drugs in the whole treatment regimen increasing the risk of cancer relapse. Metronomic chemotherapy is a modern treatment method that involves administering drugs at low doses continuously, allowing the drug sufficient time to take its effect. This method ensures that the toxicity of the drugs is to a minimum in comparison to conventional chemotherapy. Nanoparticles have shown efficacy in delivering drugs to the tumor cells in various cancer therapies. Combining nanoparticles with metronomic chemotherapy can yield better treatment results. This combination stimulates the immune system, improving cancer cells recognition by immune cells. Evidence from clinical and pre-clinical trials supports the use of metronomic delivery for drug-loaded nanoparticles. This review focuses on the functionalization of nanoparticles for improved drug delivery and inhibition of tumor growth. It emphasizes the mechanisms of metronomic chemotherapy and its conjunction with nanotechnology. Additionally, it explores tumor progression and the current methods of chemotherapy. The challenges associated with nano-based metronomic chemotherapy are outlined, paving the way for prospects in this dynamic field.

Tumor treating fields for the treatment of glioblastoma: Current understanding and future perspectives

BACKGROUND

This review focuses on the recently published evidence on tumor treating fields (TTFields) administered alone or in combination with locoregional and systemic options for treating glioblastoma (GBM) in the past ten years. The aim is to critically summarize the novelty and results obtained with this innovative tool, which is becoming part of the armamentarium of neurosurgeons and neuro-oncologists.

METHODS

A comprehensive search and analysis were conducted on pivotal studies published in the past ten years. Furthermore, all completed clinical trials, whose results were published on clinicaltrials.gov, were examined and included in the present review, encompassing both recurrent (r) and newly diagnosed (n) GBM. Finally, an additional examination of the ongoing clinical trials was also conducted.

RESULTS

Recent trials have shown promising results both in patients with nGBM and rGBM/progressive (rGBM), leading to Food and Drug Administration approval in selected patients and the Congress of Neurological Surgeons to include TTFields into current guidelines on the management of GBM (P100034/S001-029). Recently, different randomized trials have demonstrated promising results of TTFields in combination with standard treatment of n- and rGBM, especially when considering progression-free and overall survival, maintaining a low rate of mild to moderate adverse events.

CONCLUSION

Optimal outcomes were obtained in nGBM and progressive disease. A possible future refinement of TTFields could significantly impact the treatment of rGBM and the actual standard of care for GBM, given the better safety profile and survival effects.

Induced Vascular Normalization-Can One Force Tumors to Surrender to a Better Microenvironment?

Immunotherapy has changed the way many cancers are being treated. Researchers in the field of immunotherapy and tumor immunology are investigating similar questions: How can the positive benefits achieved with immunotherapies be enhanced? Can this be achieved through combinations with other agents and if so, which ones? In our view, there is an urgent need to improve immunotherapy to make further gains in the overall survival for those patients that should benefit from immunotherapy. While numerous different approaches are being considered, our team believes that drug delivery methods along with appropriately selected small-molecule drugs and drug candidates could help reach the goal of doubling the overall survival rate that is seen in some patients that are given immunotherapeutics. This review article is prepared to address how immunotherapies should be combined with a second treatment using an approach that could realize therapeutic gains 10 years from now. For context, an overview of immunotherapy and cancer angiogenesis is provided. The major targets in angiogenesis that have modulatory effects on the tumor microenvironment and immune cells are highlighted. A combination approach that, for us, has the greatest potential for success involves treatments that will normalize the tumor's blood vessel structure and alter the immune microenvironment to support the action of immunotherapeutics. So, this is reviewed as well. Our focus is to provide an insight into some strategies that will engender vascular normalization that may be better than previously described approaches. The potential for drug delivery systems to promote tumor blood vessel normalization is considered.

Circulating Immune Cell and Outcome Analysis from the Phase II Study of PD-L1 Blockade with Durvalumab for Newly Diagnosed and Recurrent Glioblastoma

PURPOSE

PD-L1 is upregulated in glioblastoma and supports immunosuppression. We evaluated PD-L1 blockade with durvalumab among glioblastoma cohorts and investigated potential biomarkers.

PATIENTS AND METHODS

MGMT unmethylated newly diagnosed patients received radiotherapy plus durvalumab (cohort A; n = 40). Bevacizumab-naïve, recurrent patients received durvalumab alone (cohort B; n = 31) or in combination with standard bevacizumab (cohort B2; n = 33) or low-dose bevacizumab (cohort B3; n = 33). Bevacizumab-refractory patients received durvalumab plus bevacizumab (cohort C; n = 22). Primary endpoints were: OS-12 (A), PFS-6 (B, B2, B3), and OS-6 (C). Exploratory biomarkers included: a systematic, quantitative, and phenotypic evaluation of circulating immune cells; tumor mutational burden (TMB); and tumor immune activation signature (IAS).

RESULTS

No cohort achieved the primary efficacy endpoint. Outcome was comparable among recurrent, bevacizumab-naïve cohorts. No unexpected toxicities were observed. A widespread reduction of effector immune cell subsets was noted among recurrent patients compared with newly diagnosed patients that was partially due to dexamethasone use. A trend of increased CD8+Ki67+ T cells at day 15 was noted among patients who achieved the primary endpoint and were not on dexamethasone. Neither TMB nor IAS predicted outcome.

CONCLUSIONS

Patients with recurrent glioblastoma have markedly lower baseline levels of multiple circulating immune cell subsets compared with newly diagnosed patients. An early increase in systemic Ki67+CD8+ cells may warrant further evaluation as a potential biomarker of therapeutic benefit among patients with glioblastoma undergoing checkpoint therapy. Dexamethasone decreased immune cell subsets. PD-L1 blockade and combination with standard or reduced dose bevacizumab was ineffective.

Relapsing High—Grade Glioma from Peritumoral Zone: Critical Review of Radiotherapy Treatment Options

Glioblastoma (GBM) is the most common and aggressive brain tumor in adults, with a median survival of about 15 months. After the prior treatment, GBM tends to relapse within the high dose radiation field, defined as the peritumoral brain zone (PTZ), needing a second treatment. In the present review, the primary role of ionizing radiation in recurrent GBM is discussed, and the current literature knowledge about the different radiation modalities, doses and fractionation options at our disposal is summarized. Therefore, the focus is on the necessity of tailoring the treatment approach to every single patient and using radiomics and PET/MRI imaging to have a relatively good outcome and avoid severe toxicity. The use of charged particle therapy and radiosensitizers to overcome GBM radioresistance is considered, even if further studies are necessary to evaluate the effectiveness in the setting of reirradiation.

A multi-center prospective study of re-irradiation with bevacizumab and temozolomide in patients with bevacizumab refractory recurrent high-grade gliomas

PURPOSE

Survival is dismal for bevacizumab refractory high-grade glioma patients. We prospectively investigated the efficacy of re-irradiation, bevacizumab, and temozolomide in bevacizumab-naïve and bevacizumab-exposed recurrent high-grade glioma, without volume limitations, in a single arm trial.

METHODS

Recurrent high-grade glioma patients were stratified based on WHO grade (4 vs. < 4) and prior exposure to bevacizumab (yes vs. no). Eligible patients received radiation using a simultaneous integrated boost technique (55 Gy to enhancing disease, 45 Gy to non-enhancing disease in 25 fractions) with bevacizumab 10 mg/kg every 2 weeks IV and temozolomide 75 mg/m² daily followed by maintenance bevacizumab 10 mg/kg every 2 weeks and temozolomide 50 mg/m² daily for 6 weeks then a 2 week holiday until progression. Primary endpoint was overall survival. Quality of life was studied using FACT-Br and FACT-fatigue scales.

RESULTS

Fifty-four patients were enrolled. The majority (n = 36, 67%) were bevacizumab pre-exposed GBM. Median OS for all patients was 8.5 months and 7.9 months for the bevacizumab pre-exposed GBM group. Patients ≥ 36 months from initial radiation had a median OS of 13.3 months compared to 7.5 months for those irradiated < 36 months earlier (p < 0.01). FACT-Br and FACT-Fatigue scores initially declined during radiation but returned to pretreatment baseline. Treatment was well tolerated with 5 patients experiencing > grade 3 lymphopenia and 2 with > grade 3 thrombocytopenia. No radiographic or clinical radiation necrosis occurred.

CONCLUSIONS

Re-irradiation with bevacizumab and temozolomide is a safe and feasible salvage treatment for patients with large volume bevacizumab-refractory high-grade glioma. Patients further from their initial radiotherapy may derive greater benefit with this regimen.

Novel Receptor Tyrosine Kinase Pathway Inhibitors for Targeted Radionuclide Therapy of Glioblastoma

Glioblastoma (GB) remains the most fatal brain tumor characterized by a high infiltration rate and treatment resistance. Overexpression and/or mutation of receptor tyrosine kinases is common in GB, which subsequently leads to the activation of many downstream pathways that have a critical impact on tumor progression and therapy resistance. Therefore, receptor tyrosine kinase inhibitors (RTKIs) have been investigated to improve the dismal prognosis of GB in an effort to evolve into a personalized targeted therapy strategy with a better treatment outcome. Numerous RTKIs have been approved in the clinic and several radiopharmaceuticals are part of (pre)clinical trials as a non-invasive method to identify patients who could benefit from RTKI. The latter opens up the scope for theranostic applications. In this review, the present status of RTKIs for the treatment, nuclear imaging and targeted radionuclide therapy of GB is presented. The focus will be on seven tyrosine kinase receptors, based on their central role in GB: EGFR, VEGFR, MET, PDGFR, FGFR, Eph receptor and IGF1R. Finally, by way of analyzing structural and physiological characteristics of the TKIs with promising clinical trial results, four small molecule RTKIs were selected based on their potential to become new therapeutic GB radiopharmaceuticals.

Treatment options for progression or recurrence of glioblastoma: a network meta-analysis

BACKGROUND

Glioblastoma (GBM) is a highly malignant brain tumour that almost inevitably progresses or recurs after first line standard of care. There is no consensus regarding the best treatment/s to offer people upon disease progression or recurrence. For the purposes of this review, progression and recurrence are considered as one entity.

OBJECTIVES

To evaluate the effectiveness of further treatment/s for first and subsequent progression or recurrence of glioblastoma (GBM) among people who have received the standard of care (Stupp protocol) for primary treatment of the disease; and to prepare a brief economic commentary on the available evidence.

SEARCH METHODS

We searched MEDLINE and Embase electronic databases from 2005 to December 2019 and the Cochrane Central Register of Controlled Trials (CENTRAL, in the Cochrane Library; Issue 12, 2019). Economic searches included the National Health Service Economic Evaluation Database (NHS EED) up to 2015 (database closure) and MEDLINE and Embase from 2015 to December 2019.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and comparative non-randomised studies (NRSs) evaluating effectiveness of treatments for progressive/recurrent GBM. Eligible studies included people with progressive or recurrent GBM who had received first line radiotherapy with concomitant and adjuvant temozolomide (TMZ).

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies and extracted data to a pre-designed data extraction form. We conducted network meta-analyses (NMA) and ranked treatments according to effectiveness for each outcome using the random-effects model and Stata software (version 15). We rated the certainty of evidence using the GRADE approach.

MAIN RESULTS

We included 42 studies: these comprised 34 randomised controlled trials (RCTs) and 8 non-randomised studies (NRSs) involving 5236 participants. We judged most RCTs to be at a low risk of bias and NRSs at high risk of bias. Interventions included chemotherapy, re-operation, re-irradiation and novel therapies either used alone or in combination. For first recurrence, we included 11 interventions in the network meta-analysis (NMA) for overall survival (OS), and eight in the NMA for progression-free survival (PFS). Lomustine (LOM; also known as CCNU) was the most common comparator and was used as the reference treatment. No studies in the NMA evaluated surgery, re-irradiation, PCV (procarbazine, lomustine, vincristine), TMZ re-challenge or best supportive care. We could not perform NMA for second or later recurrence due to insufficient data. Quality-of-life data were sparse. First recurrence (NMA findings) Median OS across included studies in the NMA ranged from 5.5 to 12.6 months and median progression-free survival (PFS) ranged from 1.5 months to 4.2 months. We found no high-certainty evidence that any treatments tested were better than lomustine. These treatments included the following. Bevacizumab plus lomustine: Evidence suggested probably little or no difference in OS between bevacizumab (BEV) combined with lomustine (LOM) and LOM monotherapy (hazard ratio (HR) 0.91, 0.75 to 1.10; moderate-certainty evidence), although BEV + LOM may improve PFS (HR 0.57, 95% confidence interval (CI) 0.44 to 0.74; low-certainty evidence). Bevacizumab monotherapy: Low-certainty evidence suggested there may be little or no difference in OS (HR 1.22, 95% CI 0.84 to 1.76) and PFS (HR 0.90, 95% CI 0.58 to 1.38; low-certainty evidence) between BEV and LOM monotherapies; more evidence on BEV is needed. Regorafenib (REG): REG may improve OS compared with LOM (HR 0.50, 95% CI 0.33 to 0.76; low-certainty evidence). Evidence on PFS was very low certainty and more evidence on REG is needed. Temozolomide (TMZ) plus Depatux-M (ABT414): For OS, low-certainty evidence suggested that TMZ plus ABT414 may be more effective than LOM (HR 0.66, 95% CI 0.47 to 0.92) and may be more effective than BEV (HR 0.54, 95% CI 0.33 to 0.89; low-certainty evidence). This may be due to the TMZ component only and more evidence is needed. Fotemustine (FOM): FOM and LOM may have similar effects on OS (HR 0.89, 95% CI 0.51 to 1.57, low-certainty evidence). Bevacizumab and irinotecan (IRI): Evidence on BEV + irinotecan (IRI) versus LOM for both OS and PFS is very uncertain and there is probably little or no difference between BEV + IRI versus BEV monotherapy (OS: HR 0.95, 95% CI 0.70 to 1.30; moderate-certainty evidence). When treatments were ranked for OS, FOM ranked first, BEV + LOM second, LOM third, BEV + IRI fourth, and BEV fifth. Ranking does not take into account the certainty of the evidence, which also suggests there may be little or no difference between FOM and LOM. Other treatments Three studies evaluated re-operation versus no re-operation, with or without re-irradiation and chemotherapy, and these suggested possible survival advantages with re-operation within the context of being able to select suitable candidates for re-operation. A cannabinoid treatment in the early stages of evaluation, in combination with TMZ, merits further evaluation. Second or later recurrence Limited evidence from three heterogeneous studies suggested that radiotherapy with or without BEV may have a beneficial effect on survival but more evidence is needed. Evidence was insufficient to draw conclusions about the best radiotherapy dosage. Other evidence suggested that there may be little difference in survival with tumour-treating fields compared with physician's best choice of treatment. We found no reliable evidence on best supportive care. Severe adverse events (SAEs) The BEV+LOM combination was associated with significantly greater risk of SAEs than LOM monotherapy (RR 2.51, 95% CI 1.72 to 3.66, high-certainty evidence), and ranked joint worst with cediranib + LOM (RR 2.51, 95% CI 1.29 to 4.90; high-certainty evidence). LOM ranked best and REG ranked second best. Adding novel treatments to BEV was generally associated with a higher risk of severe adverse events compared with BEV alone.

AUTHORS' CONCLUSIONS

For treatment of first recurrence of GBM, among people previously treated with surgery and standard chemoradiotherapy, the combination treatments evaluated did not improve overall survival compared with LOM monotherapy and were often associated with a higher risk of severe adverse events. Limited evidence suggested that re-operation with or without re-irradiation and chemotherapy may be suitable for selected candidates. Evidence on second recurrence is sparse. Re-irradiation with or without bevacizumab may be of value in selected individuals, but more evidence is needed.

Systematic review and network meta-analysis of the efficacy of existing treatments for patients with recurrent glioblastoma

Background

Despite advances in the treatment of cancers over the last years, treatment options for patients with recurrent glioblastoma (rGBM) remain limited with poor outcomes. Many regimens have been investigated in clinical trials; however, there is a lack of knowledge on comparative effectiveness. The aim of this systematic review is to provide an overview of existing treatment strategies and to estimate the relative efficacy of these regimens in terms of progression-free survival (PFS) and overall survival (OS).

Methods

We conducted a systematic review to identify randomized controlled trials (RCTs) investigating any treatment regimen in adult patients suffering from rGBM. Connected studies reporting at least one of our primary outcomes were included in a Bayesian network meta-analysis (NMA) estimating relative treatment effects.

Results

Forty RCTs fulfilled our inclusion criteria evaluating the efficacy of 38 drugs as mono- or combination therapy. Median OS ranged from 2.9 to 18.3 months; median PFS ranged from 0.7 to 6 months. We performed an NMA including 24 treatments that were connected within a large evidence network. Our NMA indicated improvement in PFS with most bevacizumab (BV)-based regimens compared to other regimens. We did not find any differences in OS between treatments.

Conclusion

This systematic review provides a comprehensive overview of existing treatment options for rGBM. The NMA provides relative effects for many of these treatment regimens, which have not been directly compared in RCTs. Overall, outcomes for patients with rGBM remain poor across all treatment options, highlighting the need for innovative treatment options.

Phase 2 trial of hypoxia activated evofosfamide (TH302) for treatment of recurrent bevacizumab-refractory glioblastoma

Evofosfamide (Evo or TH302) is a hypoxia-activated prodrug which is reduced leading to the release of alkylating agent bromo-isophosphoramide mustard, which has shown safety and signals of efficacy in a prior phase 1 study in recurrent glioblastoma. We performed a dual center single-arm Phase II study to expand on the safety and efficacy of Evo plus bevacizumab in bevacizumab refractory glioblastoma. 33 patients with bevacizumab refractory GBM received Evo 670 mg/m2 in combination with Bevacizumab 10 mg/kg IV every 2 weeks. Assessments included adverse events, response, and survival. Median age of patients was 47 (range 19-76) and 24 (69%) were male. At the time of study entry, 9 (26%) had ongoing corticosteroid use. ECOG performance status was 0 or 1 in 83% of patients. Patients were mostly heavily pretreated with 77% have three or more prior regimens. A total of 12 patients (36%) suffered grade 3-4 drug associated adverse event (AE); no grade 5 AE were reported. Of the 33 evaluable patients, best response was PR in 3 (9%), SD in 14 (43%), and PD in 16 (48%) with responses confirmed by a second reviewer. Median time to progression of disease was 53 days (95% CI 42-113) and Median time to death was 129 days (95% CI 86-199 days). Progression free survival at 4 months (PFS-4) on Evo-Bev was 31%, which was a statistically significant improvement over the historical rate of 3%. The median overall survival of patients receiving Evo-Bevacizumab was 4.6 months (95% CI 2.9-6.6). The progression free survival of patients on Evo-Bevacizumab met the primary endpoint of progression free survival at 4 months of 31%, although the clinical significance of this may be limited. Given the patient population and Phase II design, these clinical outcomes will need further validation.

De-escalating cancer treatments during COVID 19 pandemic: Is metronomic chemotherapy a reasonable option?

COVID 19 pandemic represents an emergency for public health services and containment measures to reduce the risk of infection have been promptly activated worldwide. The healthcare systems reorganization has had a major impact on the management of cancer patients who are considered at high risk of infection. Recommendations and guidelines on how to manage cancer patients during COVID 19 pandemic have been published. Oral administration of chemotherapy is recommended to limit the access of cancer patients to hospital facilities and in some cases to guarantee the continuum of care. Low-dose metronomic administration of chemotherapy with different drugs and schedules has emerged in the last years as a possible alternative to conventional chemotherapy, due to its promising tumor control rates and excellent safety profiles. Moreover, given that many metronomic schedules use the oral route administration, it could represent a therapeutic strategy to ensure continuum of cancer care during COVID 19 pandemic. In this review we have selected all the clinical studies that have used the metronomic strategy, especially with oral drugs, in order to identify the subgroups of cancer patients who can benefit most from a metronomic approach even during COVID 19 pandemic.

Repeat radiation with bevacizumab and minocycline in bevacizumab-refractory high grade gliomas: a prospective phase 1 trial

Introduction

There are no effective treatments for gliomas after progression on radiation, temozolomide, and bevacizumab. Microglia activation may be involved in radiation resistance and can be inhibited by the brain penetrating antibiotic minocycline. In this phase 1 trial, we examined the safety and effect on survival, symptom burden, and neurocognitive function of reirradiation, minocycline, and bevacizumab.

Methods

The trial used a 3 + 3 design for dose escalation followed by a ten person dose expansion. Patients received reirradiation with dosing based on radiation oncologist judgment, bevacizumab 10 mg/kg IV every two weeks, and oral minocycline twice a day. Symptom burden was measured using MDASI-BT. Neurocognitive function was measured using the COGSTATE battery.

Results

The maximum tolerated dose of minocycline was 400 mg twice a day with no unexpected toxicities. The PFS3 was 64.6%, and median overall survival was 6.4 months. Symptom burden and neurocognitive function did not decline in the interval between treatment completion and tumor progression.

Conclusions

Minocycline 400 mg orally twice a day with bevacizumab and reirradiation is well tolerated by physician and patient reported outcomes in people with gliomas that progress on bevacizumab.

Metronomic Chemotherapy: A Systematic Review of the Literature and Clinical Experience

Metronomic chemotherapy, continuous and dose-dense administration of chemotherapeutic drugs with lowered doses, is being evaluated for substituting, augmenting, or appending conventional maximum tolerated dose regimens, with preclinical and clinical studies for the past few decades. To date, the principle mechanisms of its action include impeding tumoral angiogenesis and modulation of hosts' immune system, affecting directly tumor cells, their progenitors, and neighboring stromal cells. Its better toxicity profile, lower cost, and easier use are main advantages over conventional therapies. The evidence of metronomic chemotherapy for personalized medicine is growing, starting with unfit elderly patients and also for palliative treatment. The literature reviewed in this article mainly demonstrates that metronomic chemotherapy is advantageous for selected patients and for certain types of malignancies, which make it a promising therapeutic approach for filling in the gaps. More clinical studies are needed to establish a solidified role for metronomic chemotherapy with other treatment models in modern cancer management.

Hypoxia-activated evofosfamide for treatment of recurrent bevacizumab-refractory glioblastoma: a phase I surgical study

Background

Anti-angiogenic therapy is known to induce a greater degree of hypoxia, including in glioblastoma (GBM). Evofosfamide (Evo) is a hypoxia-activated prodrug which is reduced, leading to the release of the alkylating agent bromo-isophosphoramide mustard. We assessed the safety, tolerability, preliminary efficacy, and biomarkers of Evo plus bevacizumab (Bev) in Bev-refractory GBM.

Methods

Twenty-eight patients with Bev-refractory GBM were enrolled in a dose escalation study receiving from 240 mg/m2 (cohort 1) to 670 mg/m2 (cohort 4) of Evo every 2 weeks in combination with Bev. Patients deemed surgical candidates underwent a single dose of Evo or placebo with pimonidazole immediately prior to surgery for biomarker evaluation, followed by dose escalation upon recovery. Assessments included adverse events, response, and survival.

Results

Evo plus Bev was well tolerated up to and including the maximum dose of 670 mg/m2, which was determined to be the recommended phase II dose. Overall response rate was 17.4%, with disease control (complete response, partial response, and stable disease) observed in 14 (60.9%) of the 23 patients. The ratio of enhancement to non-enhancement was significant on log-rank analysis with time to progression (P = 0.023), with patients having a ratio of less than 0.37 showing a median progression-free survival of 98 days versus 56 days for those with more enhancement.

Conclusions

Evo plus Bev was well tolerated in patients with Bev-refractory GBM, with preliminary evidence of activity that merits further investigation.

Effectiveness of lomustine and bevacizumab in progressive glioblastoma: a meta-analysis

Background

Glioblastomas (GBMs) are the most aggressive type of glial brain tumors. Despite aggressive treatment with surgery and chemoradiation, GBMs invariably relapse and tumors are progressive. Controversy remains on optimal treatment of patients with recurrent GBMs. Data from previous trials have suggested that the addition of bevacizumab (BEV) to lomustine (CCNU) might improve overall survival (OS) as compared with that with monotherapies. The aim of this study was to compare the efficacy of BEV in addition to CCNU versus single-agent therapy in patients with recurrent GBM.

Methods

Electronic databases were searched for eligible literature updated in December 2017. Trials assessing the effectiveness of CCNU and BEV in progressive GBM were included, of which the main outcomes were progression-free survival (PFS) and OS. All the data were pooled with the corresponding 95% confidence intervals (CIs) using RevMan software. Sensitivity and heterogeneity were quantitatively evaluated.

Results

Three randomized clinical trials were identified, including 574 patients (combination group: 358, monotherapies group: 216). The combination group treated with BEV and CCNU showed improvement in PFS (OR = 0.49; 95% CI, 0.41–0.59; p < 0.00001). No significant differences were, however, found in patients in terms of the OS (OR = 0.84; 95% CI, 0.68–1.03; p = 0.09).

Conclusion

Although treatment with CCNU plus BEV prolonged PFS, it did not confer OS advantage over monotherapies in patients with progressive GBM. The encouraging results of the addition of CCNU to BEV warrant investigation in further randomized trials.

Multicenter Phase IB Trial of Carboxyamidotriazole Orotate and Temozolomide for Recurrent and Newly Diagnosed Glioblastoma and Other Anaplastic Gliomas

Purpose Carboxyamidotriazole orotate (CTO) is a novel oral inhibitor of non-voltage-dependent calcium channels with modulatory effects in multiple cell-signaling pathways and synergistic effects with temozolomide (TMZ) in glioblastoma (GBM) models. We conducted a phase IB study combining CTO with two standard TMZ schedules in GBM. Methods In cohort 1, patients with recurrent anaplastic gliomas or GBM received escalating doses of CTO (219 to 812.5 mg/m² once daily or 600 mg fixed once-daily dose) combined with TMZ (150 mg/m² 5 days during each 28-day cycle). In cohort 2, patients with newly diagnosed GBM received escalating doses of CTO (219 to 481 mg/m²/d once daily) with radiotherapy and TMZ 75 mg/m²/d, followed by TMZ 150 mg to 200 mg/m² 5 days during each 28-day cycle. Results Forty-seven patients were enrolled. Treatment was well tolerated; toxicities included fatigue, constipation, nausea, and hypophosphatemia. Pharmacokinetics showed that CTO did not alter TMZ levels; therapeutic concentrations were achieved in tumor and brain. No dose-limiting toxicities were observed; the recommended phase II dose was 600 mg/d flat dose. Signals of activity in cohort 1 (n = 27) included partial (n = 6) and complete (n = 1) response, including in O⁶-methylguanine-DNA methyltransferase unmethylated and bevacizumab-refractory tumors. In cohort 2 (n = 15), median progression-free survival was 15 months and median overall survival was not reached (median follow-up, 28 months; 2-year overall survival, 62%). Gene sequencing disclosed a high rate of responses among EGFR-amplified tumors ( P = .005), with mechanisms of acquired resistance possibly involving mutations in mismatch-repair genes and/or downstream components TSC2, NF1, NF2, PTEN, and PIK3CA. Conclusion CTO can be combined safely with TMZ or chemoradiation in GBM and anaplastic gliomas, displaying favorable brain penetration and promising signals of activity in this difficult-to-treat population.

Modern reirradiation for recurrent gliomas can safely delay tumor progression

BACKGROUND

Despite advances in modern therapy, high-grade gliomas continue to portend a dismal prognosis and nearly all patients will experience relapse. Unfortunately, salvage options remain limited. In this study, we assessed outcomes for patients with recurrent gliomas treated with reirradiation.

METHODS

We retrospectively identified 48 glioma patients treated with reirradiation between 2013 and 2016. All had radiographic or pathologic evidence of recurrence. Prognostic factors were abstracted from the electronic medical record.

RESULTS

Initial surgery included biopsy in 15, subtotal resection in 21, and gross total resection in 12. Initial chemotherapy included temozolomide (TMZ) in 31, TMZ+dasatinib in 7, TMZ+vorinostat in 3, and procarbazine, lomustine, and vincristine in 2. The median dose of primary radiotherapy was 60 Gy delivered in 30 fractions. Median overall survival (OS) and progression-free survival (PFS) from initial diagnosis were 3.2 and 1.7 years, respectively. A total of 36 patients failed salvage bevacizumab before reirradiation. Salvage surgery was performed before reirradiation in 21 patients. Median time to reirradiation was 1.7 years. Median follow-up was 13.7 months from reirradiation. Concurrent systemic therapy was given in 33 patients (bevacizumab in 27, TMZ in 8, and lomustine in 2). Median PFS and OS after reirradiation were 3.2 and 6.3 months, respectively. Radionecrosis occurred in 4 patients and no radionecrosis was seen in patients receiving concurrent bevacizumab with reirradiation (0% vs 19%, P = .03).

CONCLUSIONS

Reirradiation may result in delayed tumor progression with acceptable toxicity. Prospective trials are needed to determine the impact of reirradiation on tumor progression and quality of life.

Etoposide-Bevacizumab a new strategy against human melanoma cells expressing stem-like traits

Tumors contain a sub-population of self-renewing and expanding cells known as cancer stem cells (CSCs). Putative CSCs were isolated from human melanoma cells of a different aggressiveness, Hs294T and A375 cell lines, grown under hypoxia using “sphere-forming assay”, CD133 surface expression and migration ability. We found that a cell sub-population enriched for P1 sphere-initiating ability and CD133 expression also express larger amount of VEGF-R2. Etoposide does not influence phenotype of this sub-population of melanoma cells, while a combined treatment with Etoposide and Bevacizumab significantly abolished P1 sphere-forming ability, an effect associated with apoptosis of this subset of cells. Hypoxic melanoma cells sorted for VEGF-R2/CD133 positivity also undergo apoptosis when exposed to Etoposide and Bevacizumab. When Etoposide and Bevacizumab-treated hypoxic cells were injected intravenously into immunodeficient mice revealed a reduced capacity to induce lung colonies, which also appear with a longer latency period. Hence, our study indicates that a combined exposure to Etoposide and Bevacizumab targets melanoma cells endowed with stem-like properties and might be considered a novel approach to treat cancer-initiating cells.

Salvage stereotactic radiosurgery for recurrent gliomas with prior radiation therapy

This study aims to assess the viability of salvage stereotactic radiosurgery (SRS) for recurrent malignant gliomas through assessing overall survival, local control and toxicity. We performed a retrospective review of 65 patients with 76 lesions (55 high-grade, 21 low-grade) treated with salvage SRS between 2002 and   2012. Median follow-up from salvage SRS was 14.9 months (IQR: 0.9-28.1), 8.3 months (IQR: 4.0-13.3) and 8.5 months (IQR: 3.9-15.8) for low-grade, high-grade, and combined, respectively. A 12-month overall survival from salvage SRS was 68.4, 38.7 and 47.3% for low-grade, high-grade and combined respectively. A total of 6-month local control was 86.2, 53.8 and 65.3% for low-grade, high-grade and combined, respectively. Our results indicate salvage SRS can provide acceptable survival and local control with minimal toxicity.

Metabolic alterations underlying Bevacizumab therapy in glioblastoma cells

Anti-VEGF therapy with Bevacizumab is approved for glioblastoma treatment, however, it is known that tumors acquired resistance and eventually became even more aggressive and infiltrative after treatment. In the present study we aimed to unravel the potential cellular mechanisms of resistance to Bevacizumab in glioblastoma in vitro models.

Using a panel of glioblastoma cell lines we found that Bevacizumab is able to block the secreted VEGF by the tumor cells and be internalized to the cytoplasm, inducing cytotoxicity in vitro. We further found that Bevacizumab increases the expression of hypoxic (HIF-1α and CAIX) and glycolytic markers (GLUT1 and MCT1), leading to higher glucose uptake and lactate production. Furthermore, we showed that part of the consumed glucose by the tumor cells can be stored as glycogen, hampering cell dead following Bevacizumab treatment. Importantly, we found that this change on the glycolytic metabolism occurs independently of hypoxia and before mitochondrial impairment or autophagy induction. Finally, the combination of Bevacizumab with glucose uptake inhibitors decreased in vivo tumor growth and angiogenesis and shift the expression of glycolytic proteins.

In conclusion, we reported that Bevacizumab is able to increase the glucose metabolism on cancer cells by abrogating autocrine VEGF in vitro. Define the effects of anti-angiogenic drugs at the cellular level can allow us to discover ways to revert acquired resistance to this therapeutic approaches in the future.

Clinical outcomes in recurrent glioblastoma with bevacizumab therapy: An analysis of the literature

Bevacizumab (BEV) is a common treatment for recurrent glioblastoma (GBM). After progression on BEV, there is no consensus on subsequent therapy, as multiple chemotherapy trials have failed to demonstrate discernible activity for salvage. A previous review (995 patients) estimated a progression free survival (PFS) on BEV of 4.2months (SD±2.1) with an overall survival (OS) after progression on BEV at 3.8months (SD±1). We endeavored to establish a more rigorous historical control, both as a benchmark for efficacy, and a prognostic tool for clinical practice. A comprehensive literature review was performed utilizing PubMed and societal presentation abstracts. A total 2388 patients from 53 arms of 42 studies were analyzed in three groups: 1) thirty-two studies in which survival post-BEV was determined by subtracting PFS from OS (2045 patients): PFS on BEV=4.38months (95% CI 4.09-4.68); OS post-BEV=3.36months (95% CI 3.12-3.66); 2) two studies (94 patients) in which OS post-BEV is reported: OS=3.26 (95% CI 2.39-4.42); 3) eight studies of salvage therapy after progression on BEV (249 patients): of OS post-BEV=4.46months (95% CI 3.68-5.54). These estimates provide a firm historical control for PFS on BEV, as well as OS after disease progression on BEV therapy.

Continuing or ceasing bevacizumab beyond progression in recurrent glioblastoma: an exploratory randomized phase II trial

Background

In patients with recurrent glioblastoma, the benefit of bevacizumab beyond progression remains uncertain. We prospectively evaluated continuing or ceasing bevacizumab in patients who progressed while on bevacizumab.

Methods

CABARET, a phase II study, initially randomized patients to bevacizumab with or without carboplatin (Part 1). At progression, eligible patients underwent a second randomization to continue or cease bevacizumab (Part 2). They could also receive additional chemotherapy regimens (carboplatin, temozolomide, or etoposide) or supportive care.

Results

Of 120 patients treated in Part 1, 48 (80% of the anticipated 60-patient sample size) continued to Part 2. Despite randomization, there were some imbalances in patient characteristics. The best response was stable disease in 7 (30%) patients who continued bevacizumab and 2 (8%) patients who stopped receiving bevacizumab. There were no radiological responses. Median progression-free survival was 1.8 vs 2.0 months (bevacizumab vs no bevacizumab; hazard ratio [HR], 1.08; 95% CI, .59-1.96; P = .81). Median overall survival was 3.4 vs 3.0 months (HR, .84; 95% CI, .47-1.50; P = .56 and HR .70; 95% CI .38-1.29; P = .25 after adjustment for baseline factors). Quality-of-life scores did not significantly differ between arms. While the maximum daily steroid dose was lower in the continuation arm, the difference was not statistically significant.

Conclusions

Patients who continued bevacizumab beyond disease progression did not have clear survival improvements, although the study was not powered to detect other than very large differences. While these data provide the only randomized evidence related to continuing bevacizumab beyond progression in recurrent glioblastoma, the small sample size precludes definitive conclusions and suggests this remains an open question.

Alisertib demonstrates significant antitumor activity in bevacizumab resistant, patient derived orthotopic models of glioblastoma

Aurora A kinase (AURKA), a member of the serine/threonine kinase family, plays a critical role in cell division, and it is widely overexpressed in a variety of tumors including glioblastoma (GBM). Alisertib (MLN8237) is an orally administered selective AURKA inhibitor with potent antiproliferative activity, currently undergoing clinical testing in different tumor types. In vitro evaluation of alisertib against the primary GBM lines, GBM6, GBM10, GBM12 and GBM39 showed significant antitumor activity with IC_50s ranging between 30 and 95 nM. Orthotopic xenografts of GBM10 and the bevacizumab resistant lines GBM6 and GBM39 were established by implantating 3 × 10⁵ cells in the caudate nucleus of nude mice; animals were randomized to treatment with either alisertib 30 mg/kg/day or vehicle. In all three models, treatment with alisertib resulted in a statistically significant prolongation of survival (p < 0.0001). In addition, alisertib administration in these mice decreased phosphorylated aurora-A, induced mitotic arrest and significantly decreased histone H3 phosphorylation in tumors. In conclusion, alisertib displays significant antitumor activity against primary GBM lines and xenografts, including patient derived GBM lines resistant to bevacizumab; these data support clinical translation in GBM.

A randomized phase II trial of standard dose bevacizumab versus low dose bevacizumab plus lomustine (CCNU) in adults with recurrent glioblastoma

Antiangiogenic therapy can rapidly reduce vascular permeability and cerebral edema but high doses of bevacizumab may induce selective pressure to promote resistance. This trial evaluated the efficacy of low dose bevacizumab in combination with lomustine (CCNU) compared to standard dose bevacizumab in patients with recurrent glioblastoma. Patients (N = 71) with recurrent glioblastoma who previously received radiation and temozolomide were randomly assigned 1:1 to receive bevacizumab monotherapy (10 mg/kg) or low dose bevacizumab (5 mg/kg) in combination with lomustine (90 mg/m(2)). The primary end point was progression-free survival (PFS) based on a blinded, independent radiographic assessment of post-contrast T1-weighted and non-contrast T2/FLAIR weighted magnetic resonance imaging (MRI) using RANO criteria. For 69 evaluable patients, median PFS was not significantly longer in the low dose bevacizumab + lomustine arm (4.34 months, CI 2.96-8.34) compared to the bevacizumab alone arm (4.11 months, CI 2.69-5.55, p = 0.19). In patients with first recurrence, there was a trend towards longer median PFS time in the low dose bevacizumab + lomustine arm (4.96 months, CI 4.17-13.44) compared to the bevacizumab alone arm (3.22 months CI 2.5-6.01, p = 0.08). The combination of low dose bevacizumab plus lomustine was not superior to standard dose bevacizumab in patients with recurrent glioblastoma. Although the study was not designed to exclusively evaluate patients at first recurrence, a strong trend towards improved PFS was seen in that subgroup for the combination of low dose bevacizumab plus lomustine. Further studies are needed to better identify such subgroups that may most benefit from the combination treatment.

MiR-19a promotes cell proliferation and invasion by targeting RhoB in human glioma cells

MicroRNA-19a (miR-19a) is upregulated in different types of cancers, including gliomas, but its specific role and function in gliomas have yet to be fully elucidated. In this study, we found that miR-19a was significantly upregulated in human glioma tissues and cell lines. Overexpression of miR-19a by a miR-19a mimic promoted glioma cell proliferation and invasion. In contrast, miR-19a inhibitor suppressed cell proliferation and invasion. Furthermore, by a dual-luciferase reporter assay and expression analysis, we determined that Ras homolog family member B was a direct target of miR-19a. Knockdown of Ras homolog family member B could block cell proliferation and invasion induced by the miR-19a mimic. In conclusion, our study demonstrated that miR-19a upregulation is common in gliomas and that suppression of miR-19a expression inhibits cell proliferation and invasion, which indicates that miR-19a may act as an oncogene in gliomas.

Therapeutic options in recurrent glioblastoma--An update

INTRODUCTION

Standards of care are not yet defined in recurrent glioblastoma.

METHODS

We reviewed the literature on clinical trials for recurrent glioblastoma available in PubMed and American Society of Clinical Oncology (ASCO) abstracts until June 2015.

RESULTS

Evidence is limited due to the paucity of randomized controlled studies. Second surgery or re-irradiation are options for selected patients. Alkylating chemotherapy such as nitrosoureas or temozolomide and the vascular endothelial growth factor (VEGF) antibody, bevacizumab, exhibit comparable single agent activity. Phase III data exploring the benefit of combining bevacizumab and lomustine are emerging. Novel approaches in the fields of targeted therapy, immunotherapy, and tumor metabolism are coming forward. Several biomarkers are being explored, but, except for O(6)-methylguanine DNA methyltransferase (MGMT) promoter methylation, none has assumed a role in clinical practice.

CONCLUSION

Proper patient selection, development of predictive biomarkers and randomized controlled studies are required to develop evidence-based concepts for recurrent glioblastoma.

Adverse event grading following CTCAE v3.0 underestimates hypertensive side effects in patients with glioma treated with Bevacizumab

Anti-VEGF therapy with Bevacizumab (BEV) is widely used in cases of relapsed high-grade glioma (HGG). Arterial hypertension is a known side effect of anti-VEGF therapy. 42 Patients with relapsed HGG were treated with BEV 10 mg/kg on days 1 and 15 of 28-day cycles in addition to treatment with 40 mg TMZ daily until disease progression, based on magnetic resonance imaging and/or worsening of clinical status. In a retrospective analysis, hypertensive side effects were evaluated as the primary endpoint, while survival information in addition to toxicity was analyzed as secondary endpoint. Grading which employs the Common Terminology Criteria for Adverse Events (CTCAE) version 4.0 detected hypertensive events with a significantly higher sensitivity than CTCAE version 3.0. The rate of severe hypertensive events observed as CTCAE ≥ °3 were 9.5 % in version 3.0 and 45.2 % in version 4.0. The results presented here indicate that CTCAE version 3.0 may underreport the incidence and grade of BEV-induced hypertension within clinical trials. As hypertension has not only long-term, but also severe short-term side effects, we suggest that arterial hypertension under BEV should be scored according to CTCAE version 4.0 to avoid clinically relevant hypertension-related adverse events in these patients.

ReACT Phase II trial: a critical evaluation of the use of rindopepimut plus bevacizumab to treat EGFRvIII-positive recurrent glioblastoma

Glioblastoma is the most deadly primary brain tumor in adults and has long represented a therapeutic challenge. Disease recurrence is inevitable, and the management of recurrent disease is complicated by spontaneous or induced tumor heterogeneity which confers resistance to therapy and increased oncogenicity. EGFR and the tumor-specific mutation EGFRvIII is commonly altered in glioblastoma making it an appealing therapeutic target. Immunotherapy is an emerging and promising therapeutic approach to glioma and the EGFRvIII vaccine, rindopepimut, is the first immunotherapeutic drug to enter Phase III clinical trials for glioblastoma. Rindopepimut activates a specific immune response against tumor cells harboring the EGFRvIII protein. This review evaluates the recently completed ReACT Phase II trial using rindopepimut plus bevacizumab in the setting of EGFRvIII-positive recurrent glioblastoma (Clinical Trials identifier: NCT01498328).

The Role of End-of-Life Issues in the Design and Reporting of Cancer Clinical Trials: A Structured Literature Review

BACKGROUND

Randomized controlled trials (RCTs) are important sources of information on the benefits and harms patients may expect from treatment options. The aim of this structured literature review by the German Institute for Quality and Efficiency in Health Care was to explore whether and how the end-of-life (EoL) situation of patients with advanced cancer is considered in RCTs investigating anti-cancer treatments.

METHODS

Our journal pool comprised 19 medical journals, namely five preselected key general medical journals as well as 14 specialist journals (mainly cancer) identified via a scoping search. We systematically searched these journals in MEDLINE to identify RCTs investigating anti-cancer treatments for the following four cancer types: glioblastoma, lung cancer (stage IIIb-IV), malignant melanoma (stage IV), and pancreatic cancer (search via OVID; November 2012). We selected a representative sample of 100 publications, that is, the 25 most recent publications for each cancer type. EoL was defined as a life expectancy of ≤ two years. We assessed the information provided on (1) the descriptions of the terminal stage of the disease, (2) the therapeutic goal (i.e. the intended therapeutic benefit of the intervention studied), (3) the study endpoints assessed, (4) the authors' concluding appraisal of the intervention's effects, and (5) the terminology referring to the patients' EoL situation.

RESULTS

Median survival was ≤ one year for each of the four cancer types. Descriptions of the terminal stage of the disease were ambiguous or lacking in 29/100 publications. One or more therapeutic goals were mentioned in 51/100 publications; these goals were patient-relevant in 38 publications (survival alone: 30/38; health-related quality of life (HRQoL) or HRQoL and survival: 6/38; symptom control or symptom control and survival: 2/38). Primary endpoints included survival (50%), surrogates (44%), and safety (3%). Patient-reported outcomes (PROs) were assessed in 36/100 RCTs. The implications of treatment-related harms for the patients were discussed in 22/100 appraisals. Terminology referring to the patients' EoL situation (e.g. "terminal") was scarce, whereas terms suggesting control of the disease (e.g. "cancer control") were common.

CONCLUSIONS

The EoL situation of patients with advanced cancer should be more carefully considered in clinical trials. Although the investigation and robust reporting of PROs is a prerequisite for informed decision-making in healthcare, they are rarely defined as endpoints and HRQoL is rarely mentioned as a therapeutic goal. Suggestions for improving standards for study design and reporting are presented.

Molecularly targeted therapies for recurrent glioblastoma: current and future targets

OBJECT

Glioblastoma is the most aggressive and diffusely infiltrative primary brain tumor. Recurrence is expected and is extremely difficult to treat. Over the past decade, the accumulation of knowledge regarding the molecular and genetic profile of glioblastoma has led to numerous molecularly targeted therapies. This article aims to review the literature and highlight the mechanisms and efficacies of molecularly targeted therapies for recurrent glioblastoma.

METHODS

A systematic search was performed with the phrase "(name of particular agent) and glioblastoma" as a search term in PubMed to identify all articles published up until 2014 that included this phrase in the title and/or abstract. The references of systematic reviews were also reviewed for additional sources. The review included clinical studies that comprised at least 20 patients and reported results for the treatment of recurrent glioblastoma with molecular targeted therapies.

RESULTS

A total of 42 articles were included in this review. In the treatment of recurrent glioblastoma, various targeted therapies have been tested over the past 10-15 years. The targets of interest include epidermal growth factor receptor, vascular endothelial growth factor receptor, platelet-derived growth factor receptor, Ras pathway, protein kinase C, mammalian target of rapamycin, histone acetylation, and integrins. Unfortunately, the clinical responses to most available targeted therapies are modest at best. Radiographic responses generally range in the realm of 5%-20%. Progression-free survival at 6 months and overall survival were also modest with the majority of studies reporting a 10%-20% 6-month progression-free survival and 5- to 8-month overall survival. There have been several clinical trials evaluating the use of combination therapy for molecularly targeted treatments. In general, the outcomes for combination therapy tend to be superior to single-agent therapy, regardless of the specific agent studied.

CONCLUSIONS

Recurrent glioblastoma remains very difficult to treat, even with molecular targeted therapies and anticancer agents. The currently available targeted therapy regimens have poor to modest activity against recurrent glioblastoma. As newer agents are actively being developed, combination regimens have provided the most promising results for improving outcomes. Targeted therapies matched to molecular profiles of individual tumors are predicted to be a critical component necessary for improving efficacy in future trials.

The future of antiangiogenic treatment in glioblastoma

PURPOSE OF REVIEW

A major recent clinical research focus for glioblastoma has been the therapeutic evaluation of antiangiogenic agents. Several vascular endothelial growth factor (VEGF) receptor tyrosine kinase inhibitors and a soluble decoy VEGF receptor have demonstrated nominal benefit among patients. In contrast, bevacizumab, a humanized VEGF monoclonal antibody, exhibits evidence of apparent antitumor benefit, although these data remain controversial. In this review, we summarize how results of clinical trials evaluating bevacizumab to date influence the future of this therapeutic for recurrent and newly diagnosed glioblastoma patients.

RECENT FINDINGS

Recently reported, placebo-controlled phase III studies demonstrate a meaningful progression-free survival increment, but no overall survival benefit among newly diagnosed patients treated with bevacizumab. For unclear reasons, quality-of-life surveys from these studies revealed divergent results. Among recurrent patients, uncontrolled trials demonstrate improved overall radiographic response and progression-free survival rates, although the impact of bevacizumab on overall survival remains to be defined by an ongoing randomized phase III trial.

SUMMARY

The role of bevacizumab for glioblastoma remains uncertain but will likely be strongly influenced by results of a randomized phase III study among recurrent patients as well as further investigation of gene expression biomarker profiles to identify newly diagnosed patients more likely to derive survival benefit.

Glioblastoma multiforme: Pathogenesis and treatment

Each year, about 5-6 cases out of 100,000 people are diagnosed with primary malignant brain tumors, of which about 80% are malignant gliomas (MGs). Glioblastoma multiforme (GBM) accounts for more than half of MG cases. They are associated with high morbidity and mortality. Despite current multimodality treatment efforts including maximal surgical resection if feasible, followed by a combination of radiotherapy and/or chemotherapy, the median survival is short: only about 15months. A deeper understanding of the pathogenesis of these tumors has presented opportunities for newer therapies to evolve and an expectation of better control of this disease. Lately, efforts have been made to investigate tumor resistance, which results from complex alternate signaling pathways, the existence of glioma stem-cells, the influence of the blood-brain barrier as well as the expression of 0(6)-methylguanine-DNA methyltransferase. In this paper, we review up-to-date information on MGs treatment including current approaches, novel drug-delivering strategies, molecular targeted agents and immunomodulative treatments, and discuss future treatment perspectives.

Use of bevacizumab in recurrent glioblastoma

Glioblastoma (GBM) is the most common adult primary brain neoplasm. Despite advances in treatment, GBM continues to be associated with considerable morbidity and mortality as compared with other malignancies. Standard treatment for GBM results in survival of 12.9 months (95% CI: 12.3-13.7 months) with a median progression-free survival of 7.2 months (95% CI: 6.4-8.2 months) in a modern GBM cohort. These aggressive tumors recur and treatment for recurrent GBM continues to have very poor outcomes. Prior to the use of bevacizumab, monoclonal antibody to VEGF, 6-month progression-free survival in clinical trials for recurrent GBM ranged from 9 to 15%. Trials utilizing bevacizumab and its subsequent US FDA approval have given more hope to recurrent GBM and this concise review discusses bevacizumab in recurrent GBM. This review focuses on time-to-event outcomes (overall survival, progression-free survival and 6-month progression-free survival) in clinical trials utilizing bevacizumab for the treatment of recurrent GBM. For this review, we have chosen to focus primarily on Phase II clinical trials that have been published and available in the literature (PubMed). While we focused primarily on time-to-event variables, toxicity and safety of bevacizumab is very important and this agent can be associated with serious life-threatening toxicities. We have included a general section of toxicities but for a more lengthy review please see the excellent study by Odia and colleagues.

Bevacizumab in recurrent glioblastoma: five informative patient scenarios

Glioblastoma is the most common and malignant primary brain tumour in adults. Maximum feasible surgical resection, radiotherapy and temozolomide chemotherapy at initial diagnosis have improved prognosis but rapid recurrence is typical and survival remains brief. There is an urgent need for effective new treatments and approval of the antiangiogenic agent bevacizumab for recurrent glioblastoma by Health Canada in 2009 has been the most notable recent therapeutic advance for this disease. This review with illustrative case studies highlights how bevacizumab has been incorporated into the treatment of glioblastoma in Canada and describes the ongoing controversies surrounding its clinical application.

Lessons from anti-vascular endothelial growth factor and anti-vascular endothelial growth factor receptor trials in patients with glioblastoma

Treatment of glioblastoma (GBM), the most common primary malignant brain tumor in adults, remains a significant unmet need in oncology. Historically, cytotoxic treatments provided little durable benefit, and tumors recurred within several months. This has spurred a substantial research effort to establish more effective therapies for both newly diagnosed and recurrent GBM. In this context, antiangiogenic therapy emerged as a promising treatment strategy because GBMs are highly vascular tumors. In particular, GBMs overexpress vascular endothelial growth factor (VEGF), a proangiogenic cytokine. Indeed, many studies have demonstrated promising radiographic response rates, delayed tumor progression, and a relatively safe profile for anti-VEGF agents. However, randomized phase III trials conducted to date have failed to show an overall survival benefit for antiangiogenic agents alone or in combination with chemoradiotherapy. These results indicate that antiangiogenic agents may not be beneficial in unselected populations of patients with GBM. Unfortunately, biomarker development has lagged behind in the process of drug development, and no validated biomarker exists for patient stratification. However, hypothesis-generating data from phase II trials that reveal an association between increased perfusion and/or oxygenation (ie, consequences of vascular normalization) and survival suggest that early imaging biomarkers could help identify the subset of patients who most likely will benefit from anti-VEGF agents. In this article, we discuss the lessons learned from the trials conducted to date and how we could potentially use recent advances in GBM biology and imaging to improve outcomes of patients with GBM who receive antiangiogenic therapy.

Can bevacizumab prolong survival for glioblastoma patients through multiple lines of therapy?

Glioblastoma has a poor prognosis accompanied by debilitating neurological symptoms and impaired quality of life. Effective treatment strategies are needed, beyond the current standard of care (SOC), to improve outcomes. Glioblastomas are highly vascularized with elevated levels of VEGF, representing an appropriate target for selective therapies. The role of the anti-VEGF agent bevacizumab in newly diagnosed and recurrent glioblastoma is not fully clear at this time. Although bevacizumab has demonstrated improvements in progression-free survival in newly diagnosed and recurrent glioblastoma, there remain challenges in assessing disease progression after antiangiogenic treatment. The bevacizumab mechanism of action suggests a rationale for continuing bevacizumab treatment through multiple lines of therapy, strengthened by longer progression-free and overall survival observed with bevacizumab continuation beyond progression in a Phase III study in metastatic colorectal cancer and in pooled analyses of Phase II trials in glioblastoma. A novel study (randomized, double-blind, Phase IIIb; TAMIGA [MO28347]) aims to evaluate whether continuing bevacizumab plus lomustine (as second-line therapy) and SOC (third line and beyond) improves survival compared with placebo plus lomustine and then placebo plus SOC in patients with glioblastoma who progressed after first-line bevacizumab plus SOC.

Metronomic chemotherapy from rationale to clinical studies: a dream or reality?

Metronomic chemotherapy (MC) refers to the close administration of a chemotherapeutic drug for a long time with no extended drug-free breaks. It was developed to overcome drug resistance, partly by shifting the therapeutic target from tumor cells to the tumor vasculature, with less toxicity. Because of this peculiar way of administration, MC can be viewed as a form of long-term 'maintenance' treatment, and can be integrated with standard and conventional chemotherapy in a "chemo-switching" strategy. Additional mechanisms are involved in its antitumor activity, such as activation of immunity, induction of tumor dormancy, chemotherapy-driven dependency of cancer cells, and the '4D effect'. In this paper we report the most important studies that have analyzed these processes. In fact, a number of preclinical and clinical studies in solid tumors as well as in multiple myeloma, have been reported regarding several chemotherapy drugs which have been proposed with a metronomic schedule: vinorelbine, cyclophosphamide, capecitabine, methotrexate, bevacizumab, etoposide, gemcitabine, sorafenib, everolimus and temozolomide. The results of these studies have been sometimes conflicting, highlighting the need to develop reliable tools for patient selection and stratification. However, a more precise evaluation of MC strategies with the ongoing randomized phase II/III clinical is fundamental, because of the strict correlation of this approach with translational research and target therapy. Moreover, because of the low toxicity of MC, these studies will also help to better evaluate the clinical benefit of this treatment, with a special focus on elderly and low performance status patients.

Incorporation of biomarkers in phase II studies of recurrent glioblastoma

The survival trends for glioblastoma (GBM) patients have remained largely static, reflecting a lack of improvement in the therapeutic options for patients. Less than 5 % of newly diagnosed GBM survives more than 5 years. Tumor relapse is nearly universal and the majority of patients do not respond to further systemic therapy. The results from phase II studies conducted with recurrent GBM patients have not translated to successful confirmatory studies and thus we have reached a significant roadblock in the development of new treatments for patients with recurrent GBM. The development of new, active, and potentially targeted drugs for the treatment of recurrent GBM represents a major unmet need. The incorporation of diagnostic/companion biomarker combinations into the phase II studies and appropriate stratification of the patients is lagging significantly behind other larger cancer groups such as breast, non-small cell lung cancer, and melanoma. We herein carried out a systematic review of the phase II clinical studies conducted in patients with recurrent GBM (2010-2013 inclusive) to assess the degree of biomarker incorporation within the clinical trial design.

Recurrence pattern analysis after re-irradiation with bevacizumab in recurrent malignant glioma patients

Background

The aim of the present analysis was to evaluate the recurrence pattern in patients with recurrent malignant glioma after re-irradiation in combination with bevacizumab as there is limited data on how to optimally choose dose, fractionation and delineation margins.

Methods

Thirty-one patients with recurrent malignant glioma treated with re-irradiation and bevacizumab after previous chemoradiotherapy (concurrent temozolomide 75 mg/m²/d according to the EORTC/NCIC trial) and [¹⁸ F]FET-PET and/or MRI confirmed recurrence were retrospectively analyzed. Bevacizumab was applied twice during fractionated re-irradiation (10 mg/kg, d1 + d15, median 36 Gy, conventionally fractionated). Recurrence patterns were assessed by means of [¹⁸ F]FET-PET and/or MRI.

Results

Median follow-up was 34.0 months for all patients [95%-CI, 27.7-40.3] and median post-recurrence survival 10.8 months [95%-CI, 9.2-12.4]. Concerning the recurrence patterns, 61.3% of these were located in-field (19 patients), 22.6% were marginal (7 patients) and 16.1% ex-field (5 patients). No influence on the recurrence pattern was observed according to sex, WHO grade, maintenance chemotherapy or MGMT methylation status whereas planning target volume (PTV) size had a significant influence on the recurrence pattern (p = 0.032). PTV sizes > 75 ml were associated with a higher in-field recurrence rate and lower median post-recurrence progression-free survival (8.5 vs. 4.9 months, p = 0.016).

Conclusions

After the administration of re-irradiation with bevacizumab the recurrence pattern seems to be mainly centrally located. The PTV size was the main predictor for a marginal/ex-field recurrence.

Dose-dense temozolomide: is it still promising?

Glioblastoma (GBM) has proven to be incurable despite recent progress on its standard of care using temozolomide (TMZ) as the main trunk of initial therapy for newly diagnosed GBM. One of the main reasons accounting for the dismal prognosis is attributed to lack of active therapeutic regimens at recurrence. Since TMZ is the most active cytotoxic agent against GBM, and the standard dosing of TMZ has shown favorable safety profile in clinical trials, re-challenge with TMZ in increased dose density schedules for recurrent tumors that have evaded from prior standard TMZ therapy appears to be a rational approach and has been intensively exploited. A number of phase II clinical trials using different alternating scheduling of dose-dense TMZ (ddTMZ) have shown superior efficacy over the standard TMZ or historical controls with other alkylating agents including nitrosoureas and procarbazine. One ddTMZ schedule, consisting of a 21-days on/7-days off regimen was applied to newly-diagnosed GBM as the adjuvant monotherapy after completion of combined radiation and TMZ and failed to demonstrate survival benefit in a large phase III trial (RTOG 0525). Thus its role in TMZ-pretreated, recurrent GBM should be carefully pursuit in randomized trials, e.g., planned JCOG 1308 trial comparing a 7-days on/7-days off ddTMZ regimen used upfront at the first relapse followed by bevacizumab on progression versus bevacizumab alone, investigating whether insertion of ddTMZ prior to bevacizumab could bestow better outcome in the recurrent setting. In this article, mode of action, past trials, and future directions of ddTMZ therapy are discussed.

Combinations of vascular endothelial growth factor pathway inhibitors with metronomic chemotherapy: Rational and current status

Chemotherapy given in a metronomic manner can be administered with less adverse effects which are common with conventional schedules such as myelotoxicity and gastrointestinal toxicity and thus may be appropriate for older patients and patients with decreased performance status. Efficacy has been observed in several settings. An opportunity to improve the efficacy of metronomic schedules without significantly increasing toxicity presents with the addition of anti-angiogenic targeted treatments. These combinations rational stems from the understanding of the importance of angiogenesis in the mechanism of action of metronomic chemotherapy which may be augmented by specific targeting of the vascular endothelial growth factor (VEGF) pathway by antibodies or small tyrosine kinase inhibitors. Combinations of metronomic chemotherapy schedules with VEGF pathway targeting drugs will be discussed in this paper.

Antiangiogenic therapy for glioblastoma: current status and future prospects

Glioblastoma is characterized by high expression levels of proangiogenic cytokines and microvascular proliferation, highlighting the potential value of treatments targeting angiogenesis. Antiangiogenic treatment likely achieves a beneficial impact through multiple mechanisms of action. Ultimately, however, alternative proangiogenic signal transduction pathways are activated, leading to the development of resistance, even in tumors that initially respond. The identification of biomarkers or imaging parameters to predict response and to herald resistance is of high priority. Despite promising phase II clinical trial results and patient benefit in terms of clinical improvement and longer progression-free survival, an overall survival benefit has not been demonstrated in four randomized phase III trials of bevacizumab or cilengitide in newly diagnosed glioblastoma or cediranib or enzastaurin in recurrent glioblastoma. However, future studies are warranted. Predictive markers may allow appropriate patient enrichment, combination with chemotherapy may ultimately prove successful in improving overall survival, and novel agents targeting multiple proangiogenic pathways may prove effective.

Targeted therapy in gliomas

The survival outcome of patients with malignant gliomas is still poor, despite advances in surgical techniques, radiation therapy and the development of novel chemotherapeutic agents. The heterogeneity of molecular alterations in signaling pathways involved in the pathogenesis of these tumors contributes significantly to their resistance to treatment. Several molecular targets for therapy have been discovered over the last several years. Therapeutic agents targeting these signaling pathways may provide more effective treatments and may improve survival. This review summarizes the important molecular therapeutic targets and the outcome of published clinical trials involving targeted therapeutic agents in glioma patients.

Cullin1 regulates proliferation, migration and invasion of glioma cells

This study was designed to explore the role of Cullin1 (Cul1) in the pathogenesis of human glioma and to investigate the role of Cul1 in the growth, migration and invasion of glioma cells. Expression of Cul1 in 191 glioma tissues, 8 normal brain tissues and 8 tumor adjacent normal brain tissues was analyzed by tissue microarray and immunohistochemistry. Cul1 expression in human glioblastoma cells was knocked down by specific siRNA to study the effect of down-regulation of Cul1 on proliferation, invasion and migration of glioma cells. Our results showed that Cul1 expression increased significantly in tissues from the benign tumor and malignant tumor in comparison with those from the tumor-adjacent normal brain (P<0.05 for both). We did not find any correlation between Cul1 expression and clinicopathological parameters. In addition, we found that knockdown of Cul1 by RNA interference markedly inhibited cell proliferation and caused cessation of cell cycle. This reduced cell proliferation was due to G1 phase arrest as cyclinA, cyclinD1 and cyclinE were diminished, whereas p21 and p27 were up-regulated. We further demonstrated that silencing of Cul1 in glioma cells inhibited the cell migration and invasion abilities, and down-regulation of MMP-2 and MMP-9 expression greatly contributed to the reduced cell invasion and migration abilities. Our data indicated that Cul1 expression significantly increased in human glioma, and it may be involved in proliferation, migration and invasion of glioma cells.

Curcumin inhibits vasculogenic mimicry through the downregulation of erythropoietin-producing hepatocellular carcinoma-A2, phosphoinositide 3-kinase and matrix metalloproteinase-2

Glioblastomas (GBMs) are the most common and aggressive malignant primary brain tumors found in humans. In high-grade gliomas, vasculogenic mimicry (VM) is often detected. VM is the formation of de novo vascular networks by highly invasive tumor cells, instead of endothelial cells. An understanding of the mechanisms of VM formation will contribute to the targeted therapy of GBMs. In the present study, the efficacy of curcumin (CCM) on VM formation and its mechanisms were investigated. It was found that CCM inhibits the VM formation, proliferation, migration and invasion of human glioma U251 cells in a dose-dependent manner. Furthermore, CCM downregulated the protein and mRNA expression of erythropoietin-producing hepatocellular carcinoma-A2, phosphoinositide 3-kinase and matrix metalloproteinase-2, indicating that CCM may function through these factors for the inhibition of VM formation. These data provide novel insights into the use of CCM to antagonize VM, and may contribute to the angiogenesis-targeted therapy of malignant glioma.