One week on/one week off: A novel active regimen of temozolomide for recurrent glioblastoma

Temozolomide – Just a Radiosensitizer?

Radiation concomitant with the DNA methylating drug temozolomide (TMZ) is the gold standard in the treatment of glioblastoma. In this adjuvant setting, TMZ is regarded to be a radiation sensitizer. However, similar to ionising radiation, TMZ induces DNA double-strand breaks and is itself a potent trigger of apoptosis, cellular senescence and autophagy, suggesting that radiation and TMZ act independently. Although cell culture experiments yielded heterogeneous results, some data indicate that the cytotoxic effect of radiation was only enhanced when TMZ was given before radiation treatment. Based on the molecular mechanism of action of TMZ, the importance of specific TMZ and radiation-induced DNA lesions, their repair as well as their interactions, possible scenarios for an additive or synergistic effect of TMZ and radiation are discussed, and suggestions for an optimal timing of radio-chemical treatments are proposed.

Accumulation of Temozolomide-Induced Apoptosis, Senescence and DNA Damage by Metronomic Dose Schedule: A Proof-of-Principle Study with Glioblastoma Cells

Simple Summary

Severe toxic side effects do not allow unlimited dose escalation of anticancer drugs, and the doses used in cancer therapy are therefore often rather low regarding the required target concentration. For temozolomide (TMZ), which is used in glioblastoma therapy, single high dose protocols are used in nearly all experimental studies, while the drug is administered repeatedly on patients, with a daily (metronomic) low dose schedule. Here, we show that the therapeutically relevant glioblastoma cell death and senescence responses do accumulate if a high dose of TMZ is split up in small low doses. The data support the metronomic dose schedule and suggest that even low doses are effective in glioblastoma therapy. The predominance and accumulation of TMZ-refractory senescent survivors may provide an explanation for the overall low curative response.

Abstract

Temozolomide (TMZ), a first-line drug in glioma therapy, targets the tumor DNA at various sites. One of the DNA alkylation products is O⁶-methylguanine (O⁶MeG), which is, in the low dose range of TMZ, responsible for nearly all genotoxic and cytotoxic effects relevant for cancer therapy. There is, however, a dispute regarding whether the TMZ concentration in the tumor tissue in patients is sufficient to elicit a significant cytotoxic or cytostatic response. Although treatment with TMZ occurs repeatedly with daily doses (metronomic dose schedule) and in view of the short half-life of the drug it is unclear whether doses are accumulating. Here, we addressed the question whether repeated low doses elicit similar effects in glioblastoma cells than a high cumulative dose. We show that repeated treatments with a low dose of TMZ (5 × 5 µM) caused an accumulation of cytotoxicity through apoptosis, cytostasis through cellular senescence, and DNA double-strand breaks, which was similar to the responses induced by a single cumulative dose of 25 µM TMZ. This finding, together with the previously reported linear dose–response curves, support the notion that TMZ is able to trigger a significant cytotoxic and cytostatic effect in vivo if the low-dose metronomic schedule is applied.

The current landscape of systemic therapy for recurrent glioblastoma: A systematic review of randomized-controlled trials

AIM

Conduct a systematic review of the effectiveness of systemic therapies for adult recurrent glioblastoma (rGBM).

METHODS

We electronically searched for randomized controlled trials from three major databases and four conferences from 2009-Dec 2020. Two independent reviewers conducted screening, data extraction, and quality assessment.

RESULTS

48 randomized trials were identified. Outcome reporting was inconsistent: overall survival (OS) in 46 studies, progression free survival in 37 studies, 6-month PFS in 30 studies, objective response rate in 28 studies, and 6-month OS in 7 studies. Network meta-analysis was not feasible due to heterogeneity in outcome reporting and single-study linkages. Most studies compared lomustine (8 studies), bevacizumab (18), or temozolomide (8) with other treatments. The median OS across all studies ranged from 3 to 17.6 months.

CONCLUSIONS

Based on level one evidence, there is no superior systemic regimen for rGBM. rGBM is a heterogeneous population with no single regimen demonstrating OS benefit. Registration number: CRD42020148512.

Molecular Dosimetry of Temozolomide: Quantification of Critical Lesions, Correlation to Cell Death Responses, and Threshold Doses

Temozolomide (TMZ) is a DNA-methylating agent used in cancer chemotherapy, notably for glioblastoma multiforme (GBM), where it is applied as a front-line drug. One of the DNA alkylation products of TMZ is the minor lesion O⁶ -methylguanine (O⁶ MeG), which is responsible for nearly all genotoxic, cytotoxic, and cytostatic effects induced in the low-dose range relevant for cancer therapy. Here, we addressed the question of how many O⁶ MeG adducts are required to elicit cytotoxic responses. Adduct quantification revealed that O⁶ MeG increases linearly with dose. The same was observed for DNA double-strand breaks (DSB) and p53ser15. Regarding apoptosis, hockeystick modeling indicated a possible threshold for A172 cells at 2.5 μmol/L TMZ, whereas for LN229 cells no threshold was detected. Cellular senescence, which is the main cellular response, also increased linearly, without a threshold. Using a dose of 20 μmol/L, which is achievable in a therapeutic setting, we determined that 14,000 adducts give rise to 32 DSBs (γH2AX foci) in A172 cells. This leads to 12% cell death and 35% of cells entering senescence. In LN229 cells, 20 μmol/L TMZ induced 20,600 O⁶ MeG adducts, 66 DSBs (γH2AX foci), 24% apoptosis, and 52% senescence. The linear dose response and the genotoxic and cytotoxic effects observed at therapeutically relevant dose levels make it very likely that the TMZ target concentration triggers a significant cytotoxic and cytostatic effect in vivo Despite a linear increase in the O⁶ MeG adduct level, DSBs, and p53 activation, the low curative effect of TMZ results presumably from the low rate of apoptosis compared to senescence.

Temozolomide: An Updated Overview of Resistance Mechanisms, Nanotechnology Advances and Clinical Applications

Temozolomide (TMZ), an oral alkylating prodrug which delivers a methyl group to purine bases of DNA (O6-guanine; N7-guanine and N3-adenine), is frequently used together with radiotherapy as part of the first-line treatment of high-grade gliomas. The main advantages are its high oral bioavailability (almost 100% although the concentration found in the cerebrospinal fluid was approximately 20% of the plasma concentration of TMZ), its lipophilic properties, and small size that confer the ability to cross the blood-brain barrier. Furthermore, this agent has demonstrated activity not only in brain tumors but also in a variety of solid tumors. However, conventional therapy using surgery, radiation, and TMZ in glioblastoma results in a median patient survival of 14.6 months. Treatment failure has been associated with tumor drug resistance. This phenomenon has been linked to the expression of O6-methylguanine-DNA methyltransferase, but the mismatch repair system and the presence of cancer stem-like cells in tumors have also been related to TMZ resistance. The understanding of these mechanisms is essential for the development of new therapeutic strategies in the clinical use of TMZ, including the use of nanomaterial delivery systems and the association with other chemotherapy agents. The aim of this review is to summarize the resistance mechanisms of TMZ and the current advances to improve its clinical use.

Temozolomide treatment outcomes and immunotherapy efficacy in brain tumor

INTRODUCTION

Glioblastoma (GBM) has a survival rate of around 2 years with aggressive current standard of care. While other tumors have responded favorably to trials combining immunotherapy and chemotherapy, GBM remains uniformly deadly with minimal increases in overall survival. GBM differ from others due to being isolated behind the blood brain barrier, increased heterogeneity and mutational burden, and immunosuppression from the brain environment and tumor itself.

METHODS

We have reviewed clinical and preclinical studies investigating how different doses (dose intense (DI) and metronomic) and timing of immunotherapy following TMZ treatment can eradicate tumor cells, alter tumor mutational burden, and change immune cells.

RESULTS

Recent clinical trials with standard of care (SoC), DI and metronomic TMZ regimes are no able to completely eradicate GBM. Elevated TMZ levels in DI treatment can overcome MGMT resistance but may result in hypermutation of surviving tumor cells. Higher levels of TMZ will also generate a higher degree of lymphopenia compared to SoC and metronomic regimes in preclinical studies.

CONCLUSION

The different levels of lymphopenia and tumor eradication discussed in this review suggest possible beneficial pairings between immunotherapy and TMZ treatment. Treatments resulting in profound lymphopenia will allow for expansion of vaccine specific T cells or of CAT T cells. Clinical and preclinical studies are currently comparing different combinations of TMZ and immunotherapy timing to treat GBM through a balance between tumor killing and immune cell expansion. More frequent immune monitoring time points in ongoing clinical trials are crucial for further development of these combinations.

Cytotoxic and Senolytic Effects of Methadone in Combination with Temozolomide in Glioblastoma Cells

Methadone is an analgesic drug used for pain treatment and heroin substitution. Recently, methadone has been proposed to be useful also for cancer therapy, including glioblastoma multiforme (GBM), the most severe form of brain cancer, because experiments on cultured glioma cells treated with doxorubicin showed promising results. Doxorubicin, however, is not used first-line in GBM therapy. Therefore, we analyzed the cytotoxic effect of methadone alone and in combination with temozolomide, a DNA-alkylating drug that is first-line used in GBM treatment, utilizing GBM-derived cell lines and a human fibroblast cell line. We show that methadone is cytotoxic on its own, inducing apoptosis and necrosis, which was observed at a concentration above 20 µg/mL. Methadone was similar toxic in isogenic MGMT expressing and non-expressing cells, and in LN229 glioblastoma and VH10T human fibroblasts. The apoptosis-inducing activity of methadone is not bound on the opioid receptor (OR), since naloxone, a competitive inhibitor of OR, did not attenuate methadone-induced apoptosis/necrosis. Administrating methadone and temozolomide together, temozolomide had no impact on methadone-induced apoptosis (which occurred 3 days after treatment), while temozolomide-induced apoptosis (which occurred 5 days after treatment) was unaffected at low (non-toxic) methadone concentration (5 µg/mL), and at high (toxic) methadone concentration (20 µg/mL) the cytotoxic effects of methadone and temozolomide were additive. Methadone is not genotoxic, as revealed by comet and γH2AX assay, and did not ameliorate the genotoxic effect of temozolomide. Further, methadone did not induce cellular senescence and had no effect on temozolomide-induced senescence. Although methadone was toxic on senescent cells, it cannot be considered a senolytic drug since cytotoxicity was not specific for senescent cells. Finally, we show that methadone had no impact on the MGMT promoter methylation. Overall, the data show that methadone on glioblastoma cells in vitro is cytotoxic and induces apoptosis/necrosis at doses that are above the level that can be achieved in vivo. It is not genotoxic, and does not ameliorate the cell killing or the senescence-inducing effect of temozolomide (no synergistic effect), indicating it has no impact on temozolomide-induced signaling pathways. The data do not support the notion that concomitant methadone treatment supports temozolomide-based chemotherapy.

Considering the Experimental use of Temozolomide in Glioblastoma Research

Temozolomide (TMZ) currently remains the only chemotherapeutic component in the approved treatment scheme for Glioblastoma (GB), the most common primary brain tumour with a dismal patient's survival prognosis of only ~15 months. While frequently described as an alkylating agent that causes DNA damage and thus-ultimately-cell death, a recent debate has been initiated to re-evaluate the therapeutic role of TMZ in GB. Here, we discuss the experimental use of TMZ and highlight how it differs from its clinical role. Four areas could be identified in which the experimental data is particularly limited in its translational potential: 1. transferring clinical dosing and scheduling to an experimental system and vice versa; 2. the different use of (non-inert) solvent in clinic and laboratory; 3. the limitations of established GB cell lines which only poorly mimic GB tumours; and 4. the limitations of animal models lacking an immune response. Discussing these limitations in a broader biomedical context, we offer suggestions as to how to improve transferability of data. Finally, we highlight an underexplored function of TMZ in modulating the immune system, as an example of where the aforementioned limitations impede the progression of our knowledge.

Development and in vivo evaluation of Irinotecan-loaded Drug Eluting Seeds (iDES) for the localised treatment of recurrent glioblastoma multiforme

Glioblastoma multiforme (GBM) is impossible to fully remove surgically and almost always recurs at the borders of the resection cavity, while systemic delivery of therapeutic drug levels to the brain tumour is limited by the blood-brain barrier. This research describes the development of a novel formulation of Irinotecan-loaded Drug Eluting Seeds (iDES) for insertion into the margin of the GBM resection cavity to provide a sustained high local dose with reduced systemic toxicities. We used primary GBM cells from both the tumour core and Brain Around the Tumour tissue from recurrent GBM patients to demonstrate that irinotecan is more effective than temozolomide. Irinotecan had a 75% response rate, while only 50% responded to temozolomide. With temozolomide the cell viability was never below 80% whereas irinotecan achieved cell viabilities of less than 44%. The iDES were manufactured using a hot melt extrusion process with accurate irinotecan drug loadings and the same cytotoxicity as unformulated irinotecan. The iDES released irinotecan in a sustained fashion for up to 7 days. However, only the 30, 40 and 50% w/w loaded iDES formulations released the 300 to 1000 μg of irinotecan needed to be effective in vivo. The 30 and 40% w/w iDES formulations containing 10% plasticizer and either 60 or 50% PLGA prolonged survival from 27 to 70 days in a GBM xenograft mouse resection model with no sign of tumour recurrence. The 30% w/w iDES formulations showed equivalent toxicity to a placebo in non-tumour bearing mice. This innovative drug delivery approach could transform the treatment of recurrent GBM patients by improving survival and reducing toxicity.

Comment in Response to "Temozolomide in Glioblastoma Therapy: Role of Apoptosis, Senescence and Autophagy etc. by B. Kaina"

It is with great pleasure that we acknowledge the fact that our review on Temozolomide (TMZ) has initiated a discussion [1-3]. [...].

Are There Thresholds in Glioblastoma Cell Death Responses Triggered by Temozolomide?

Temozolomide (TMZ) is an alkylating agent used in the treatment of high-grade malignant glioma, notably glioblastoma multiforme, the most aggressive form of brain cancer. The drug induces a dozen DNA methylation adducts, including O⁶-methylguanine (O⁶MeG), which is the most toxic primary DNA lesion as it causes the formation of DNA double-strand breaks (DSBs) that trigger apoptosis. In p53 wild-type cells, TMZ activates p-p53ser15 and p-p53ser46, which have opposing dual functions regulating survival and death, respectively. Since the use of TMZ in a therapeutic setting is limited because of its side effects, the question arises as to the existence of threshold doses that activate the death pathway and start apoptosis. To determine whether there is a threshold for the TMZ-induced DNA damage response and exploring the factors regulating the switch between p53 dependent survival and death, the glioblastoma lines LN-229 (deficient in MGMT) and LN-229MGMT (stably transfected with MGMT) were exposed to different doses of TMZ. p53 protein expression and phosphorylation levels of p-p53ser15 and p-p53ser46 were determined by Western blotting. Also, apoptosis, senescence and autophagy levels were checked after different doses of TMZ. The results show that pro-survival p-p53ser15 and pro-death p-p53ser46 were induced by O⁶MeG in a specific dose- and time-dependent manner. p-p53ser15 was an early response while p-p53ser46 was activated at later times following treatment. Unexpectedly, the dose-response curves for total p53, p-p53ser15 and p-p53ser46 were linear, without an obvious threshold. O⁶MeG induces apoptosis late after treatment as a linear function of TMZ dose. This was observed for both p53 proficient LN-229 and p53 lacking LN-308 cells. A linear dose-response after TMZ was also observed for senescence and autophagy as well as γH2AX, an indicator of DSBs that are considered to be the downstream trigger of apoptosis, senescence and autophagy. LN-229MGMT cells were highly resistant to all measured endpoints because of repair of the critical primary lesion. Although LN-308 were less responsive than LN-229 to TMZ, they displayed the same TMZ-induced DSB level. The observed linear dose-responses are not compatible with the view that low DNA damage level evokes survival while high damage level activates death functions. The data bear important therapeutic implications as they indicate that even low doses of TMZ may elicit a cytotoxic response. However, since O⁶MeG triggers apoptosis, senescence and autophagy in the same dose range, it is likely that the accumulation of senescent cells in the population counteracts the killing effect of the anticancer drug.

Phase 1 lead-in to a phase 2 factorial study of temozolomide plus memantine, mefloquine, and metformin as postradiation adjuvant therapy for newly diagnosed glioblastoma

BACKGROUND

Repurposed memantine, mefloquine, and metformin have putative anticancer activity. The objective of this phase 1 study was to determine the maximum tolerated doses (MTDs) of combinations of these agents with temozolomide (TMZ).

METHODS

Adults with newly diagnosed glioblastoma who completed chemoradiation were eligible. The patients were assigned to receive doublet, triplet, or quadruplet therapy with TMZ combined with mefloquine, memantine, and/or metformin. Dose-limiting toxicities (DLTs) were determined, using a 3 + 3 study design.

RESULTS

Of 85 enrolled patients, 4 did not complete cycle 1 (the DLT observation period) for nontoxicity reasons, and 81 were evaluable for DLT. The MTDs for doublet therapy were memantine 20 mg twice daily, mefloquine 250 mg 3 times weekly, and metformin 850 mg twice daily. For triplet therapy, the MTDs were memantine 10 mg twice daily, mefloquine 250 mg 3 times weekly, and metformin 850 mg twice daily. For quadruplet therapy, the MTDs were memantine 10 mg twice daily, mefloquine 250 mg 3 times weekly, and metformin 500 mg twice daily. DLTs included dizziness (memantine) and gastrointestinal effects (metformin). Lymphopenia was the most common adverse event (66%). From study entry, the median survival was 21 months, and the 2-year survival rate was 43%.

CONCLUSIONS

Memantine, mefloquine, and metformin can be combined safely with TMZ in patients with newly diagnosed glioblastoma.

Versatile Synthesis of Polymer-Temozolomide Conjugates

A new and versatile synthesis was developed to produce polymer prodrugs composed of poly(2-methacryloyloxyethyl phosphorylcholine) (polyMPC) conjugated covalently to the glioblastoma drug Temozolomide (TMZ). Through a controlled free radical copolymerization of a TMZ-substituted methacrylate and MPC, water-soluble polyMPC-TMZ conjugates were realized with TMZ loadings of >50 mol %. After polymerization, the structural fidelity of the pendent TMZ moieties was confirmed by NMR and UV-vis spectroscopy, while molecular weight estimation by gel permeation chromatography (GPC) confirmed the desired control over the polymerization, with isolated polymer-TMZ conjugates exhibiting narrow molecular weight distributions. This synthetic design opens new possibilities for formulating numerous types of polymeric TMZ-based structures that are of interest for treating glioblastoma.

Recurrent Glioblastoma: Combination of High Cerebral Blood Flow with MGMT Promoter Methylation Is Associated with Benefit from Low-Dose Temozolomide Rechallenge at First Recurrence

Purpose To determine if the combination of high cerebral blood flow (CBF) and O⁶-methylguanine DNA methyltransferase (MGMT) promoter methylation is associated with benefit from a second round of low-dose temozolomide (TMZ) (ie, rechallenge) in patients with glioblastoma at first recurrence. Materials and Methods The institutional review board approved this retrospective cohort study and waived the requirement for informed consent. Seventy-two patients with recurrent glioblastoma after concurrent TMZ radiation therapy were treated with a low-dose TMZ rechallenge and underwent arterial spin labeling magnetic resonance imaging. The cohort was dichotomized to high-CBF and low-CBF subgroups. MGMT promoter methylation was determined before concurrent TMZ radiation therapy. The coprimary end points were median time to progression (TTP) and 6-month outcome after the initiation of low-dose TMZ. The Cox proportional hazards model was used to assess the association between clinical outcome and CBF status. Results There was a significant difference between the high- and low-CBF cohorts in median TTP (6 months vs 3 months, respectively; P = .001). Favorable 6-month outcomes occurred in 16 of 31 (52%) patients with high CBF and six of 41 (15%) patients with low CBF (P = .001). At multivariate analysis, high CBF was independently associated with longer TTP (P = .023). The association between high CBF and favorable outcome was significant only in the MGMT promoter methylation group (P = .006 for TTP; P = .005 for 6-month outcome). Conclusion The combination of high CBF with MGMT methylation may be associated with benefits from a low-dose TMZ rechallenge in patients with recurrent glioblastoma. However, alternative strategies might be needed for patients with both low CBF and a lack of MGMT methylation. ^© RSNA, 2016 Online supplemental material is available for this article.

Malignant gliomas: old and new systemic treatment approaches

Background

Malignant (high-grade) gliomas are rapidly progressive brain tumours with very high morbidity and mortality. Until recently, treatment options for patients with malignant gliomas were limited and mainly the same for all subtypes of malignant gliomas. The treatment included surgery and radiotherapy. Chemotherapy used as an adjuvant treatment or at recurrence had a marginal role.

Conclusions

Nowadays, the treatment of malignant gliomas requires a multidisciplinary approach. The treatment includes surgery, radiotherapy and chemotherapy. The chosen approach is more complex and individually adjusted. By that, the effect on the survival and quality of life is notable higher.

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.

Treating recurrent glioblastoma: an update

Glioblastoma, the most aggressive of the gliomas, has a high recurrence and mortality rate. The nature of this poor prognosis resides in the molecular heterogeneity and phenotypic features of this tumor. Despite research advances in understanding the molecular biology, it has been difficult to translate this knowledge into effective treatment. Nearly all will have tumor recurrence, yet to date very few therapies have established efficacy as salvage regimens. This challenge is further complicated by imaging confounders and to an even greater degree by the ever increasing molecular heterogeneity that is thought to be both sporadic and treatment-induced. The development of novel clinical trial designs to support the development and testing of novel treatment regimens and drug delivery strategies underscore the need for more precise techniques in imaging and better surrogate markers to help determine treatment response. This review summarizes recent approaches to treat patients with recurrent glioblastoma and considers future perspectives.

Patterns of care in recurrent glioblastoma in Switzerland: a multicentre national approach based on diagnostic nodes

Despite moderate improvements in outcome of glioblastoma after first-line treatment with chemoradiation recent clinical trials failed to improve the prognosis of recurrent glioblastoma. In the absence of a standard of care we aimed to investigate institutional treatment strategies to identify similarities and differences in the pattern of care for recurrent glioblastoma. We investigated re-treatment criteria and therapeutic pathways for recurrent glioblastoma of eight neuro-oncology centres in Switzerland having an established multidisciplinary tumour-board conference. Decision algorithms, differences and consensus were analysed using the objective consensus methodology. A total of 16 different treatment recommendations were identified based on combinations of eight different decision criteria. The set of criteria implemented as well as the set of treatments offered was different in each centre. For specific situations, up to 6 different treatment recommendations were provided by the eight centres. The only wide-range consensus identified was to offer best supportive care to unfit patients. A majority recommendation was identified for non-operable large early recurrence with unmethylated MGMT promoter status in the fit patients: here bevacizumab was offered. In fit patients with late recurrent non-operable MGMT promoter methylated glioblastoma temozolomide was recommended by most. No other majority recommendations were present. In the absence of strong evidence we identified few consensus recommendations in the treatment of recurrent glioblastoma. This contrasts the limited availability of single drugs and treatment modalities. Clinical situations of greatest heterogeneity may be suitable to be addressed in clinical trials and second opinion referrals are likely to yield diverging recommendations.

The efficacy and safety of various dose-dense regimens of temozolomide for recurrent high-grade glioma: a systematic review with meta-analysis

The goal of this meta-analysis was to identify the temozolomide (TMZ) regimen with optimal efficacy and tolerance for treatment of recurrent high-grade glioma (HGG). The PubMed and EMBASE databases were searched from the earliest records to February 2015, which identified 33 studies with 1760 participants that met the inclusion criteria. The standard schedule and three most common dose-dense regimens of TMZ therapy for recurrent HGG were included in this meta-analysis. The schedule of 7 days on/7 days off for the treatment of grade IV gliomas was significantly superior to the standard regimen with respect to progression-free survival at 6 months (34.8 %; 95 % confidence interval (CI) 27.0-43.4 %) and 12 months (15.5 %; 95 % CI 10.7-21.8 %). For grade III gliomas, this regimen conveyed a significantly greater overall survival (OS) rate at 12 months (79.0 %; 95 % CI 56.2-91.7 %), as compared to the standard schedule. Also, the 21 days on/7 days off regimen had significantly longer OS rates at 6 months (73.6 %; 95 % CI 63.4-81.8 %) and 12 months (40.6 %; 95 % CI 32.6-48.6 %) than the standard regimen for grade IV gliomas. In addition, the standard schedule showed a significantly higher clinical benefit rate than the 7 days on/7 days off and 21 days on/7 days off regimens. However, the grade 3-4 toxicity rate of lymphopenia of the standard schedule was 76.5 % (95 % CI 45.5-92.7 %), which was the highest among the four regimens. Recurrent HGG patients receiving personalized treatment should be closely followed up, especially those with concurrent hematological diseases.

A phase II study of feasibility and toxicity of bevacizumab in combination with temozolomide in patients with recurrent glioblastoma

PURPOSE

The aim of this prospective and multicentric phase II study was to evaluate the efficacy and safety of temozolomide (TMZ) and bevacizumab (BV) in patients (pts) with recurrent glioblastoma (GB), previously treated with chemoradiotherapy and at least three cycles of adjuvant TMZ.

PATIENTS AND METHODS

Patients with GB at first relapse received BV 10 mg/kg day every 2 weeks and TMZ 150 mg/m(2) days 1-7 and 15-21, every 28 days. Patients underwent brain magnetic resonance imaging every 8 weeks.

RESULTS

Thirty-two evaluable pts were recruited in 8 sites. Fourteen pts (44%) had gross total resection. O(6)-methylguanine-DNA methyltransferase (MGMT) promoter was methylated in 12 pts, unmethylated in 6 pts, and missing in 14 pts. The estimated 6-month progression free survival (PFS) rate was 21.9% (95% CI 9.3-40.0%). The median PFS and overall survival (OS) were 4.2 months (95% CI 3.6-5.4 months) and 7.3 months (95% CI 5.8-8.8 months), respectively. No significant association with MGMT status was found in terms of OS or PFS. Six of 32 pts (19%; 95% CI 7.2-36.4) were long-term survivors, with a median PFS and OS (50% events) of 9.5 months (95% CI 7.9-23.6) and 15.4 (95% CI 8.9-NA), respectively: no differences in baseline characteristics were identified in comparison with total population. No unexpected toxicities or treatment-related deaths were observed.

CONCLUSIONS

This regimen showed to be feasible and well tolerated in pts with recurrent GB pretreated with TMZ. Further investigation is warranted to identify subpopulations that are more likely to benefit from addition of BV to GB therapy.

The future of high-grade glioma: Where we are and where are we going

High-grade glioma (HGG) are optimally treated with maximum safe surgery, followed by radiotherapy (RT) and/or systemic chemotherapy (CT). Recently, the treatment of newly diagnosed anaplastic glioma (AG) has changed, particularly in patients with 1p19q codeleted tumors. Results of trials currenlty ongoing are likely to determine the best standard of care for patients with noncodeleted AG tumors. Trials in AG illustrate the importance of molecular characterization, which are germane to both prognosis and treatment. In contrast, efforts to improve the current standard of care of newly diagnosed glioblastoma (GB) with, for example, the addition of bevacizumab (BEV), have been largely disappointing and furthermore molecular characterization has not changed therapy except in elderly patients. Novel approaches, such as vaccine-based immunotherapy, for newly diagnosed GB are currently being pursued in multiple clinical trials. Recurrent disease, an event inevitable in nearly all patients with HGG, continues to be a challenge. Both recurrent GB and AG are managed in similar manner and when feasible re-resection is often suggested notwithstanding limited data to suggest benefit from repeat surgery. Occassional patients may be candidates for re-irradiation but again there is a paucity of data to commend this therapy and only a minority of selected patients are eligible for this approach. Consequently systemic therapy continues to be the most often utilized treatment in recurrent HGG. Choice of therapy, however, varies and revolves around re-challenge with temozolomide (TMZ), use of a nitrosourea (most often lomustine; CCNU) or BEV, the most frequently used angiogenic inhibitor. Nevertheless, no clear standard recommendation regarding the prefered agent or combination of agents is avaliable. Prognosis after progression of a HGG remains poor, with an unmet need to improve therapy.

MGMT Promoter Methylation Is a Strong Prognostic Biomarker for Benefit from Dose-Intensified Temozolomide Rechallenge in Progressive Glioblastoma: The DIRECTOR Trial

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 time-to-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 methylation-specific 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.

Randomized phase II adjuvant factorial study of dose-dense temozolomide alone and in combination with isotretinoin, celecoxib, and/or thalidomide for glioblastoma

BACKGROUND

Chemoradiation, followed by adjuvant temozolomide, is the standard treatment for newly diagnosed glioblastoma. Adding other active agents may enhance treatment efficacy.

METHODS

The primary objective of this factorial phase II study was to determine if one of 3 potential chemotherapy agents added to dose-dense temozolomide (ddTMZ) improves progression-free survival (PFS) for patients with newly diagnosed glioblastoma. A prior phase I trial established the safety of combining ddTMZ with isotretinoin, celecoxib, and/or thalidomide. Adults with good performance status and no evidence of progression post chemoradiation were randomized into 8 arms: ddTMZ alone (7 days on/7 days off) or doublet, triplet, and quadruplet combinations with isotretinoin, celecoxib, and thalidomide.

RESULTS

The study enrolled 155 participants with a median age of 53 years (range, 18-84 y). None of the agents demonstrated improved PFS when compared with arms not containing that specific agent. There was no difference in PFS for triplet compared with doublet regimens, although a trend for improved overall survival (OS) was seen (20.1 vs 17.0 months, P = .15). Compared with ddTMZ, the ddTMZ + isotretinoin doublet had worse PFS (10.5 vs 6.5 months, P = .043) and OS (21.2 vs 11.7 months, P = .037). Trends were also seen for worse outcomes with isotretinoin-containing regimens, but there was no impact with celecoxib or thalidomide combinations. Treatment was well tolerated with expected high rates of lymphopenia.

CONCLUSIONS

The results do not establish a benefit for these combinations but indicate that adding isotretinoin to ddTMZ may be detrimental. This study demonstrated the feasibility and utility of the factorial design in efficiently testing drug combinations in newly diagnosed glioblastoma.

CLINICALTRIALSGOV IDENTIFIER

NCT00112502.

Salvage therapy for recurrent glioblastoma multiforme: a multimodal approach combining fluorescence-guided resurgery, interstitial irradiation, and chemotherapy

OBJECTIVES

Several studies have revealed that different salvage treatments in glioblastoma multiforme patients presenting a recurrence have limited palliative treatment options. The aim of this study was to evaluate the utility and limitations of multimodal salvage treatments in recurrent glioblastoma multiforme patients combining 5-aminolevulinic acid (5-ALA) fluorescence-guided resurgery, interstitial irradiation, and dense dose temozolomide chemotherapy (ddTMZ).

METHODS

Seventeen consecutive patients with recurrent globlastoma multiforme underwent a combined scheme of salvage treatments including fluorescence-guided reoperation, high dose rate (HDR) brachytherapy, and ddTMZ chemotherapy and were included in this prospective study. This multimodal treatment group was compared with a 1∶1 matched historical control group of 17 patients who have been treated with intensive temozolomide chemotherapy as the only treatment modality. All patients were previously treated with surgery of the primary pathology, concomitant, and adjuvant radiochemotherapy with temozolomide.

RESULTS

Median follow-up was 32 months (range: 28-36 months). Median survival was 9 months for the entire cohort after salvage treatment and can be translated into a 3-month improvement in survival compared to the control group of patients with glioblastoma recurrence treated with temozolomide alone (P  =  0·043). Complications rates of multimodal salvage treatment were comparable with the temozolomide control group.

DISCUSSION

Our experience suggests that a combined salvage treatment plan have the advantages of all three methods and, thus, provide additional survival benefit and can be considered in selected patients affected by recurrent high grade gliomas. Nonetheless, more cases and additional studies are necessary to further prove the advantages of this multimodal treatment.

Phase II trial of 7 days on/7 days off temozolmide for recurrent high-grade glioma

BACKGROUND

A phase II trial was performed to evaluate the efficacy of a dose-dense, 7 days on/7 days off schedule of temozolomide for patients with recurrent high-grade gliomas (HGG).

METHODS

Sixty patients with recurrent HGG received temozolomide at 150 mg/m(2)/day on days 1-7 and days 15-21 during each 4-week cycle. The primary endpoint was 6-month progression-free survival (PFS-6), with a secondary endpoint of overall survival (OS). A further exploratory objective included the investigation of whether methylation status of the O(6)-methylguanine-DNA methyltransferase (MGMT) promoter within tumor tissue predicted outcomes.

RESULTS

Among patients with glioblastoma (n = 40), PFS-6 was 10% (95% CI, 3%-24%) with median OS of 21.6 weeks (95% CI, 16.9-30.6 weeks). PFS-6 for grade III glioma patients (n = 20) was 50% (95% CI, 27%-73%), and median OS was 100.6 weeks (95% CI, 67 weeks to not reached). There were trends towards longer PFS and OS with MGMT promoter methylation (log-rank test; P = .06 for PFS; P = .07 for OS). Additionally, bevacizumab-naïve glioblastoma patients had significantly longer PFS and OS (median PFS was 8.07 weeks [95% CI, 8 weeks to not reached] vs 7.57 weeks [95% CI, 7.29-8.29 weeks], log-rank test, P < .001; median OS was 62 weeks [26.1 weeks to not reached] vs 18.2 weeks [13.9-27.3 weeks], log-rank test, P < .001).

CONCLUSIONS

The dose-dense temozolomide regimen was well tolerated, although it has no significant activity in this population. Clinical trials.gov identified. NCT00619112 (available at http://clinicaltrials.gov/ct2/show/NCT00619112).

Prophylactic use of pegfilgrastim in patients treated with a nitrosourea and teniposide for recurrent glioma

STUDY OBJECTIVE

As chemotherapy with teniposide and a nitrosourea is commonly used for the treatment of patients with recurrent glioma but can be associated with severe myelotoxicity, we sought to determine if prophylactic administration of pegfilgrastim could reduce leukopenia or infectious complications in patients receiving this chemotherapeutic regimen.

DESIGN

Retrospective medical record review.

SETTING

University-affiliated neurooncology hospital in Frankfurt, Germany.

PATIENTS

Sixty-four patients who received at least one cycle of a nitrosourea agent (nimustine or lomustine) and teniposide for recurrent glioma between 2008 and 2012; of these patients, 28 did not receive prophylactic pegfilgrastim (cohort A), and 36 patients received prophylactic pegfilgrastim (cohort B).

MEASUREMENTS AND MAIN RESULTS

Blood counts, hospitalizations due to infection or myelosuppression, use of intravenous antibiotics, and survival parameters were analyzed. Leukopenia was more frequently observed before day 30 (early nadir) versus from 30 days until the next cycle (late nadir). In cohort B, Common Terminology Criteria for Adverse Events grade 3 leukopenia in the early nadir occurred less often compared with cohort A (9% in cohort B vs 31% in cohort A). However, the frequency of grade 4 leukopenia, number of days in the hospital due to infection or myelosuppression, days on intravenous antibiotics, progression-free survival, and overall survival were similar between the cohorts.

CONCLUSION

Moderate, but not severe, leukopenia or related complications could be prevented by prophylactic pegfilgrastim in patients treated with a nitrosourea and teniposide for recurrent glioma. Our results, therefore, do not support routine prophylactic use of pegfilgrastim in these patients.

Low-dose fractionated radiotherapy and concomitant chemotherapy for recurrent or progressive glioblastoma: final report of a pilot study

BACKGROUND

Evaluated in this study were the feasibility and the efficacy of concurrent low dose fractionated radiotherapy (LD-FRT) and chemotherapy as palliative treatment for recurrent/progressive glioblastoma multiforme (GBM).

PATIENTS AND METHODS

Eligible patients had recurrent or progressive GBM, Karnofsky performance status ≥ 70, prior surgery, and standard radiochemotherapy treatment. Recurrence/progression disease during temozolomide (TMZ) received cisplatin (CDDP; 30 mg/m(2) on days 1, 8, 15), fotemustine (FTM; 40 mg/m(2) on days 2, 9, 16), and concurrent LD-FRT (0.3 Gy twice daily); recurrence/progression after 4 months from the end of adjuvant TMZ were treated by TMZ (150/200 mg/m(2) on days 1-5) concomitant with LD-FRT (0.4 Gy twice daily). Primary endpoints were safety and toxicity.

RESULTS

A total of 32 patients were enrolled. Hematologic toxicity G1-2 was observed in 18.7 % of patients and G3-4 in 9.4 %. One patient (3.1 %) had complete response, 3 (9.4 %) had partial response, 8 (25 %) had stable disease for at least 8 weeks, while 20 patients (62.5 %) experienced progressive disease. The clinical benefit was 37.5 %. Median progression-free survival (PFS) and overall survival (OS) were 5 and 8 months, respectively. Survival rate at 12 months was of 27.8 %.

CONCLUSION

LD-FRT and chemotherapy for recurrent/progressive GBM have a good toxicity profile and clinical outcomes, even though further investigation of this novel palliative treatment approach is warranted.

Progression-free survival as a surrogate endpoint for overall survival in glioblastoma: a literature-based meta-analysis from 91 trials

Background

The aim of this study was to determine correlations between progression-free survival (PFS) and the objective response rate (ORR) with overall survival (OS) in glioblastoma and to evaluate their potential use as surrogates for OS.

Method

Published glioblastoma trials reporting OS and ORR and/or PFS with sufficient detail were included in correlative analyses using weighted linear regression.

Results

Of 274 published unique glioblastoma trials, 91 were included. PFS and OS hazard ratios were strongly correlated; R² = 0.92 (95% confidence interval [CI], 0.71–0.99). Linear regression determined that a 10% PFS risk reduction would yield an 8.1% ± 0.8% OS risk reduction. R² between median PFS and median OS was 0.70 (95% CI, 0.59–0.79), with a higher value in trials using Response Assessment in Neuro-Oncology (RANO; R² = 0.96, n = 8) versus Macdonald criteria (R² = 0.70; n = 83). No significant differences were demonstrated between temozolomide- and bevacizumab-containing regimens (P = .10) or between trials using RANO and Macdonald criteria (P = .49). The regression line slope between median PFS and OS was significantly higher in newly diagnosed versus recurrent disease (0.58 vs 0.35, P = .04). R² for 6-month PFS with 1-year OS and median OS were 0.60 (95% CI, 0.37–0.77) and 0.64 (95% CI, 0.42–0.77), respectively. Objective response rate and OS were poorly correlated (R² = 0.22).

Conclusion

In glioblastoma, PFS and OS are strongly correlated, indicating that PFS may be an appropriate surrogate for OS. Compared with OS, PFS offers earlier assessment and higher statistical power at the time of analysis.

Hypofractionated stereotactic radiation therapy for recurrent glioblastoma: single institutional experience

BACKGROUND

Glioblastoma (GBM) is the most common malignant primary brain tumor in adults. Tumor control and survival have improved with the use of radiotherapy (RT) plus concomitant and adjuvant chemotherapy, but the prognosis remain poor. In most cases the recurrence occurs within 7-9 months after primary treatment. Currently, many approaches are available for the salvage treatment of patients with recurrent GBM, including resection, re-irradiation or systemic agents, but no standard of care exists.

METHODS

We analysed a cohort of patients with recurrent GBM treated with frame-less hypofractionated stereotactic radiation therapy with a total dose of 25 Gy in 5 fractions.

RESULTS

Of 91 consecutive patients with newly diagnosed GBM treated between 2007 and 2012 with conventional adjuvant chemo-radiation therapy, 15 underwent salvage RT at recurrence. The median time interval between primary RT and salvage RT was 10.8 months (range, 6-54 months). Overall, patients undergoing salvage RT showed a longer survival, with a median survival of 33 vs. 9.9 months (p= 0.00149). Median overall survival (OS) from salvage RT was 9.5 months. No patients demonstrated clinically significant acute morbidity, and all patients were able to complete the prescribed radiation therapy without interruption.

CONCLUSION

Our results suggest that hypofractionated stereotactic radiation therapy is effective and safe in recurrent GBM. However, until prospective randomized trials will confirm these results, the decision for salvage treatment should remain individual and based on a multidisciplinary evaluation of each patient.

Survival analysis of HDR brachytherapy versus reoperation versus temozolomide alone: a retrospective cohort analysis of recurrent glioblastoma multiforme

OBJECTIVES

Tumour recurrence of glioblastoma multiforme (GBM) after initial treatment with surgical resection, radiotherapy and chemotherapy is an inevitable phenomenon. This retrospective cohort study compared the efficacy of interstitial high dose rate brachytherapy (HDR-BRT), re-resection and sole dose dense temozolomide chemotherapy (ddTMZ) in the treatment of recurrent glioblastoma after initial surgery and radiochemotherapy.

DESIGN

Retropective cohort study.

SETTING

Primary level of care with two participating centres. The geographical location was central Germany.

PARTICIPANTS

From January 2005 to December 2010, a total of 111 patients developed recurrent GBM after initial surgery and radiotherapy with concomitant temozolomide. The inclusion criteria were as follows: (1) histology-proven diagnosis of primary GBM (WHO grade 4), (2) primary treatment with resection and radiochemotherapy, and (3) tumour recurrence/progression.

INTERVENTIONS

This study compared retrospectively the efficacy of interstitial HDR-BRT, re-resection and ddTMZ alone in the treatment of recurrent glioblastoma.

PRIMARY AND SECONDARY OUTCOME MEASURES

Median survival, progression free survival and complication rate.

RESULTS

Median survival after salvage therapy of the recurrence was 37, 30 and 26 weeks, respectively. The HDR-BRT group did significantly better than both the reoperation (p<0.05) and the ddTMZ groups (p<0.05). Moderate to severe complications in the HDR-BRT, reoperation and sole chemotherapy groups occurred in 5/50 (10%), 4/36 (11%) and 9/25 (36%) cases, respectively.

CONCLUSIONS

CT-guided interstitial HDR-BRT attained higher survival benefits in the management of recurrent glioblastoma after initial surgery and radiotherapy with concurrent temozolomide in comparison with the other treatment modalities. The low risk of complications of the HDR-BRT and the fact that it can be delivered percutaneously in local anaesthesia render it a promissing treatment option for selected patients which should be further evaluated.

"One week on-one week off": efficacy and side effects of dose-intensified temozolomide chemotherapy: experiences of a single center

To evaluate in a single center retrospectively the efficacy and tolerability of a weekly regimen, which alternates temozolomide (TMZ) in patients with recurrent or progressive high-grade glioma (HGG). From January 2005 until June 2011, 54 patients with recurrent or progressive HGG were treated with TMZ 150 mg/m²/day on days 1-7 and 15-21 of a 28-day cycle ("one week on-one week off" scheme; TMZ 7/14) with individual dose adjustment depending on toxicity. The majority of patients (n = 48, 89 %) was treated at first tumor recurrence or progression. All patients had received prior radiotherapy with or without concomitantly administered TMZ and, optionally, adjuvant chemotherapy. After initiation of TMZ 7/14, MRI was obtained every 8-12 weeks. Tumor response or progression was assessed according to Macdonald criteria. Blood examinations were performed weekly. Toxicity was evaluated according to Common Terminology Criteria for Adverse Events (CTCAE; version 3.0). A total of 434 treatment weeks with TMZ 7/14 were delivered. The median number of treatment weeks was 7 (range, 1-41 weeks). No grade 4 hematological toxicity and no opportunistic infections occurred. Patients with neutropenia were not observed. Two patients developed grade 3 and 4 patients grade 2 leukocytopenia. Thrombocytopenia grade 3 and grade 2 occurred in 4 patients and 6 patients, respectively. The progression-free survival (PFS) rate at 6 months was 43 %. Median PFS from treatment initiation was 18 weeks (95 % CI, 14-22 weeks) and median overall survival (OS) was 37 weeks (95 % CI, 31-42 weeks). The rates for PFS and OS at 1 year were 24 and 28 %, respectively. Our data suggest that treatment with TMZ 7/14 is safe and effective in patients with recurrent or progressive HGG.

Standards of care for treatment of recurrent glioblastoma--are we there yet?

Newly diagnosed glioblastoma is now commonly treated with surgery, if feasible, or biopsy, followed by radiation plus concomitant and adjuvant temozolomide. The treatment of recurrent glioblastoma continues to be a moving target as new therapeutic principles enrich the standards of care for newly diagnosed disease. We reviewed PubMed and American Society of Clinical Oncology abstracts from January 2006 to January 2012 to identify clinical trials investigating the treatment of recurrent or progressive glioblastoma with nitrosoureas, temozolomide, bevacizumab, and/or combinations of these agents. At recurrence, a minority of patients are eligible for second surgery or reirradiation, based on appropriate patient selection. In temozolomide-pretreated patients, progression-free survival rates at 6 months of 20%-30% may be achieved either with nitrosoureas, temozolomide in various dosing regimens, or bevacizumab. Combination regimens among these agents or with other drugs have not produced evidence for superior activity but commonly produce more toxicity. More research is needed to better define patient profiles that predict benefit from the limited therapeutic options available after the current standard of care has failed.

Response assessment of bevacizumab in patients with recurrent malignant glioma using [18F]Fluoroethyl-L-tyrosine PET in comparison to MRI

PURPOSE

To investigate prospectively the potential of O-(2-[(18)F]fluoroethyl)-L-tyrosine ((18)F-FET) PET in comparison to MRI for the assessment of the response of patients with recurrent high-grade glioma (rHGG) to antiangiogenic treatment.

METHODS

Ten patients with rHGG were treated biweekly with bevacizumab/irinotecan (BEV/IR). MR images and dynamic (18)F-FET PET scans were obtained at baseline and at follow-up after the start of treatment (median 4.9 weeks). Using MRI treatment response was evaluated according to RANO (Response Assessment in Neuro-Oncology) criteria. For (18)F-FET PET evaluation, a reduction >45 % of the metabolically active tumour volume was considered as a treatment response, with the metabolically active tumour being defined as a tumour-to-brain ratio (TBR) of ≥1.6. The results of the treatment assessments were related to progression-free survival (PFS) and overall survival (OS). For further evaluation of PET data, maximum and mean TBR were calculated using region-of-interest analysis at baseline and at follow-up. Additionally, (18)F-FET uptake kinetic studies were performed at baseline and at follow-up in all patients. Time-activity curves were generated and the times to peak (TTP) uptake (in minutes from the beginning of the dynamic acquisition to the maximum uptake) were calculated.

RESULTS

At follow-up, MRI showed a complete response according to RANO criteria in one of the ten patients (10 %), a partial response in five patients (50 %), and stable disease in four patients (40 %). Thus, MRI did not detect tumour progression. In contrast, (18)F-FET PET revealed six metabolic responders (60 %) and four nonresponders (40 %). In the univariate survival analyses, a response detected by (18)F-FET PET predicted a significantly longer PFS (median PFS, 9 vs. 3 months; P = 0.001) and OS (median OS 23.0 months vs. 3.5 months; P = 0.001). Furthermore, in four patients (40 %), diagnosis according to RANO criteria and by (18)F-FET PET was discordant. In these patients, PET was able to detect tumour progression earlier than MRI (median time benefit 10.5 weeks; range 6-12 weeks). At baseline and at follow-up, in nonresponders TTP was significantly shorter than in responders (baseline TTP 10 ± 8 min vs. 35 ± 9 min; P = 0.002; follow-up TTP 23 ± 9 min vs. 39 ± 8 min; P = 0.02). Additionally, at baseline a kinetic pattern characterized by an early peak of (18)F-FET uptake followed by a constant descent was more frequently observed in the nonresponders (P = 0.018).

CONCLUSION

Both standard and kinetic imaging parameters derived from(18)F-FET PET seem to predict BEV/IR treatment failure and thus contribute important additional information for clinical management over and above the information obtained by MRI response assessment based on RANO criteria.

Improving the extent of malignant glioma resection by dual intraoperative visualization approach

Despite continuing debates around cytoreductive surgery in malignant gliomas, there is broad consensus that increased extent of tumor reduction improves overall survival. However, maximization of the extent of tumor resection is hampered by difficulty in intraoperative discrimination between normal and pathological tissue. In this context, two established methods for tumor visualization, fluorescence guided surgery with 5-ALA and intraoperative MRI (iMRI) with integrated functional neuronavigation were investigated as a dual intraoperative visualization (DIV) approach. Thirty seven patients presumably suffering from malignant gliomas (WHO grade III or IV) according to radiological appearance were included. Twenty-one experimental sequences showing complete resection according to the 5-ALA technique were confirmed by iMRI. Fourteen sequences showing complete resection according to the 5-ALA technique could not be confirmed by iMRI, which detected residual tumor. Further analysis revealed that these sequences could be classified as functional grade II tumors (adjacent to eloquent brain areas). The combination of fluorescence guided resection and intraoperative evaluation by high field MRI significantly increased the extent of tumor resection in this subgroup of malignant gliomas located adjacent to eloquent areas from 61.7% to 100%; 5-ALA alone proved to be insufficient in attaining gross total resection without the danger of incurring postoperative neurological deterioration. Furthermore, in the case of functional grade III gliomas, iMRI in combination with functional neuronavigation was significantly superior to the 5-ALA resection technique. The extent of resection could be increased from 57.1% to 71.2% without incurring postoperative neurological deficits.

Discrepant MR and [(18)F]Fluoroethyl-L-Tyrosine PET Imaging Findings in a Patient with Bevacizumab Failure

Antiangiogenic treatment using bevacizumab may cause difficulties in distinguishing between antivascular and true antitumor effects when using MRI response criteria based on changes of contrast enhancement (i.e., Macdonald criteria). Furthermore, more precise tumor response assessment criteria (i.e., RANO criteria), which incorporate nonenhancing T2/FLAIR sequences into Macdonald criteria, may be influenced by other causes of T2/FLAIR hyperintensity (e.g., radiation-induced gliosis). The authors present discrepant MR and [¹⁸F]fluoroethyl-L-tyrosine PET imaging findings in a patient with bevacizumab treatment failure.

Temozolomide chemotherapy alone versus radiotherapy alone for malignant astrocytoma in the elderly: the NOA-08 randomised, phase 3 trial

BACKGROUND

Radiotherapy is the standard care in elderly patients with malignant astrocytoma and the role of primary chemotherapy is poorly defined. We did a randomised trial to compare the efficacy and safety of dose-dense temozolomide alone versus radiotherapy alone in elderly patients with anaplastic astrocytoma or glioblastoma.

METHODS

Between May 15, 2005, and Nov 2, 2009, we enrolled patients with confirmed anaplastic astrocytoma or glioblastoma, age older than 65 years, and a Karnofsky performance score of 60 or higher. Patients were randomly assigned 100 mg/m(2) temozolomide, given on days 1-7 of 1 week on, 1 week off cycles, or radiotherapy of 60·0 Gy, administered over 6-7 weeks in 30 fractions of 1·8-2·0 Gy. The primary endpoint was overall survival. We assessed non-inferiority with a 25% margin, analysed for all patients who received at least one dose of assigned treatment. This trial is registered with ClinicalTrials.gov, number NCT01502241.

FINDINGS

Of 584 patients screened, we enrolled 412. 373 patients (195 randomly allocated to the temozolomide group and 178 to the radiotherapy group) received at least one dose of treatment and were included in efficacy analyses. Median overall survival was 8·6 months (95% CI 7·3-10·2) in the temozolomide group versus 9·6 months (8·2-10·8) in the radiotherapy group (hazard ratio [HR] 1·09, 95% CI 0·84-1·42, p(non-inferiority)=0·033). Median event-free survival (EFS) did not differ significantly between the temozolomide and radiotherapy groups (3·3 months [95% CI 3·2-4·1] vs 4·7 [4·2-5·2]; HR 1·15, 95% CI 0·92-1·43, p(non-inferiority)=0·043). Tumour MGMT promoter methylation was seen in 73 (35%) of 209 patients tested. MGMT promoter methylation was associated with longer overall survival than was unmethylated status (11·9 months [95% CI 9·0 to not reached] vs 8·2 months [7·0-10·0]; HR 0·62, 95% CI 0·42-0·91, p=0·014). EFS was longer in patients with MGMT promoter methylation who received temozolomide than in those who underwent radiotherapy (8·4 months [95e% CI 5·5-11·7] vs 4·6 [4·2-5·0]), whereas the opposite was true for patients with no methylation of the MGMT promoter (3·3 months [3·0-3·5] vs 4·6 months [3·7-6·3]). The most frequent grade 3-4 intervention-related adverse events were neutropenia (16 patients in the temozolomide group vs two in the radiotherapy group), lymphocytopenia (46 vs one), thrombocytopenia (14 vs four), raised liver-enzyme concentrations (30 vs 16), infections (35 vs 23), and thromboembolic events (24 vs eight).

INTERPRETATION

Temozolomide alone is non-inferior to radiotherapy alone in the treatment of elderly patients with malignant astrocytoma. MGMT promoter methylation seems to be a useful biomarker for outcomes by treatment and could aid decision-making.

FUNDING

Merck Sharp & Dohme.

Efficacy of clinically relevant temozolomide dosing schemes in glioblastoma cancer stem cell lines

The effectiveness of temozolomide (TMZ) dosing schemes and the "rechallenge" of recurrent glioblastoma (GBM) with TMZ are controversial. We therefore compared the efficacy of different TMZ dosing schemes against GBM cancer stem cell (CSC) lines in vitro. In O(6)-methyl-guanidine-methyl-transferase (MGMT)-negative CSC lines, all schedules (1 day on/27 days off, 5 days on/23 days off, 7 days on/7 days off, 21 days on/7 days off, continuous low-dose TMZ) depleted clonogenic cells. In TMZ-resistant CSC lines, the 7 days on/7 days off scheme showed higher toxicity as compared with the other schemes. However, clinically feasible concentrations remained ineffective in highly resistant CSC lines. In addition, none of the schedules induced long-term depletion of clonogenic cells even at the highest concentrations (up to 250 μM). After sublethal TMZ treatment for 5 days, TMZ rechallenge of recovering CSC lines remained effective. Our data advocate CSC lines as in vitro model to address clinical questions. Using this model, our data suggest the effectiveness of TMZ in MGMT-negative CSC lines and support the concept of TMZ rechallenge. The 7 days on/7 days off scheme consistently showed the best activity of all schedules in TMZ-resistant CSC lines.

Bevacizumab and daily temozolomide for recurrent glioblastoma

BACKGROUND

The authors performed a phase 2 trial of combined protracted daily temozolomide and biweekly bevacizumab for patients with recurrent glioblastoma who had previously received radiation therapy and temozolomide.

METHODS

There was no limit on the number of previous disease progressions or previous regimens allowed. Thirty-two adult patients were enrolled. Patients received temozolomide 50 mg/m(2) daily and bevacizumab 10 mg/kg intravenously every 14 days. Patients underwent physical examination and brain magnetic resonance imaging every 8 weeks.

RESULTS

The authors observed a 6-month progression-free survival (PFS) rate of 18.8% (95% confidence interval [CI], 7.6%-33.7%) and a median PFS of 15.8 weeks. The median overall survival (OS) was 37 weeks, the 6-month OS rate was 62.5% (95% CI, 43.5%-76.7%), and the 12-month OS rate was 31.3% (95% CI, 16.4%-47.3%). Nine patients (28%) had a radiographic response, and 7 patients (22%) had disease progression within the first 8 weeks of treatment. Patterns of progression were available for 21 patients. The authors observed that 52% of patients (n = 11) progressed locally, 38% (n = 8) progressed with a diffuse pattern, and 10% (n = 2) progressed at a distant site. Two patients discontinued therapy secondary to toxicity (prolonged thrombocytopenia and grade 4 pancreatitis). One patient experienced grade 5 pneumonia.

CONCLUSIONS

The current study demonstrated that a regimen of combined daily temozolomide and biweekly bevacizumab had some activity and was well tolerated. However, the results obtained in this study were inferior to those observed in studies of bevacizumab monotherapy and of combined irinotecan and bevacizumab therapy. The current patient population was more heterogeneous and was pretreated more heavily than patients in previous studies.

Towards tailored therapy of glioblastoma multiforme

Gliobastoma multiform (GBM) is the most common and aggressive brain tumor, which is characterized by its infiltrative nature. Current standard therapy for GBMs consists of surgery followed by radiotherapy combined with the alkylating agent temozolomide (TMZ). Recent clinical trials have demonstrated that this chemo-irradiation approach results in a significant increase in survival compared to radiotherapy alone. Nevertheless, due to tumor recurrence, the median survival time is still limited to approximately 15 months. Recently, several studies have focused on aberrant signal transduction in GBM, resistance mechanisms of GBM to TMZ and to radiotherapy. Attention has been focused on molecular targets including phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway, protein kinase C (pKC) pathway, Ras/mitogen-activated protein kinase pathway (MAPK), Wnt pathway and intrinsic or extrinsic apoptosis pathways. In addition, research has been directed to radiotherapy and radiosensitizing agents, and cancer gene therapy as well. This article will address several resistance mechanisms of GBM to chemotherapy and radiotherapy and the recent preclinical and clinical studies on targeted therapy.

Recurrent glioblastoma: a fresh look at current therapies and emerging novel approaches

Despite international efforts, the treatment of recurrent glioblastoma (GBM) remains challenging. Although advances in surgical resection, the use of radiotherapy, and, predominantly, improved medical therapies have led to incremental improvements in median survival, few options exist for the management of recurrent or resistant disease. Insight into the molecular pathogenesis of GBM has led to the recent development of targeted therapeutic strategies aimed at the interruption of key molecular signaling pathways. However, due to the complex and redundant activation of the signaling mechanisms in GBM tumors, the evaluation of targeted agents in clinical trials has been largely limited. The ongoing effort to identify effective strategies for the treatment of recurrent GBM includes combination strategies with agents that target complementary or redundant pathways. Incorporation of novel trial designs that permit simultaneous evaluation of several agent combinations and allow for rapid discontinuation of ineffective regimens can accelerate the clinical evaluation of such candidate regimens. This review discusses strategies and outcomes of existing and emerging treatment approaches, and the challenges associated with the integration of novel therapies into clinical practice.

Classification and management of anaplastic gliomas

PURPOSE OF REVIEW

To summarize findings, discuss problems and define new questions from the past phase III trials in anaplastic gliomas.

RECENT FINDINGS

The current standard of care for first-line treatment in anaplastic gliomas is radiotherapy or chemotherapy. The next steps are to define the role and optimal sequencing of combined modality treatment focusing on radiotherapy and temozolomide and to develop trials with novel targeted treatments. The feature of necrosis in oligodendroglial tumors needs to be further studied, and molecular prognosticators will take more room. These include O⁶-methylguanylmethyltransferase promoter methylation, isocitrate dehydrogenase mutations and epidermal growth factor receptor amplification. Further, the notion that all anaplastic oligodendroglial tumors with or without a relevant astrocytic component fall into the same prognostic category and the obvious difficulties to type and to grade anaplastic gliomas pose an enormous burden on local diagnosis. The current and upcoming trials including the European Organization for Research and Treatment of Cancer 26053/22054 trial aim at solving some of these issues with an initial central pathology review.

SUMMARY

Anaplastic gliomas are an important group of brain tumors to develop future molecularly targeted therapies and should therefore be in the main focus of academic and industrial drug development, which aims at efficacy and avoiding long-term side effects.