Phase 2 trial design in neuro-oncology revisited: a report from the RANO group

A critical analysis of neuro-oncology clinical trials

BACKGROUND

Limitations in trial design, accrual, and data reporting impact efficient and reliable drug evaluation in cancer clinical trials. These concerns have been recognized in neuro-oncology but have not been comprehensively evaluated. We conducted a semi-automated survey of adult interventional neuro-oncology trials, examining design, interventions, outcomes, and data availability trends.

METHODS

Trials were selected programmatically from ClinicalTrials.gov using primary malignant central nervous system tumor classification terms. Regression analyses assessed design and accrual trends; effect size analysis utilized survival rates among trials investigating survival.

RESULTS

Of 3038 reviewed trials, most trials reporting relevant information were nonblinded (92%), single group (65%), nonrandomized (51%), and studied glioblastomas (47%) or other gliomas. Basic design elements were reported by most trials, with reporting increasing over time (OR = 1.24, P < .00001). Trials assessing survival outcomes were estimated to assume large effect sizes of interventions when powering their designs. Forty-two percent of trials were completed; of these, 38% failed to meet their enrollment target, with worse accrual over time (R = -0.94, P < .00001) and for US versus non-US based trials (OR = 0.5, P < .00001). Twenty-eight percent of completed trials reported partial results, with greater reporting for US (34.6%) versus non-US based trials (9.3%, P < .00001). Efficacy signals were detected by 15%-23% of completed trials reporting survival outcomes.

CONCLUSION

Low randomization rates, underutilization of controls, and overestimation of effect size, particularly pronounced in early-phase trials, impede generalizability of results. Suboptimal designs may be driven by accrual challenges, underscoring the need for cooperative efforts and novel designs. The limited results reporting highlights the need to incentivize data reporting and harmonization.

Recurrent Glioblastoma: Ongoing Clinical Challenges and Future Prospects

Virtually all glioblastomas treated in the first-line setting will recur in a short period of time, and the search for alternative effective treatments has so far been unsuccessful. Various obstacles remain unresolved, and no effective salvage therapy for recurrent glioblastoma can be envisaged in the short term. One of the main impediments to progress is the low incidence of the disease itself in comparison with other pathologies, which will be made even lower by the recent WHO classification of gliomas, which includes molecular alterations. This new classification helps refine patient prognosis but does not clarify the most appropriate treatment. Other impediments are related to clinical trials: glioblastoma patients are often excluded from trials due to their advanced age and limiting neurological symptoms; there is also the question of how best to measure treatment efficacy, which conditions the design of trials and can affect the acceptance of results by oncologists and medicine agencies. Other obstacles are related to the drugs themselves: most treatments cannot cross the blood-brain-barrier or the brain-to-tumor barrier to reach therapeutic drug levels in the tumor without producing toxicity; the drugs under study may have adverse metabolic interactions with those required for symptom control; identifying the target of the drug can be a complex issue. Additionally, the optimal method of treatment - local vs systemic therapy, the choice of chemotherapy, irradiation, targeted therapy, immunotherapy, or a combination thereof - is not yet clear in glioblastoma in comparison with other cancers. Finally, in addition to curing or stabilizing the disease, glioblastoma therapy should aim at maintaining the neurological status of the patients to enable them to return to their previous lifestyle. Here we review currently available treatments, obstacles in the search for new treatments, and novel lines of research that show promise for the future.

Balancing Risk and Efficiency in Drug Development for Rare and Challenging Tumors: A New Paradigm for Glioma

The process of developing cancer therapies is well established and has enabled the incorporation of many new drugs and classes of agents into the standard of care for common cancers. Clinical drug development is fundamentally different for rare and difficult-to-treat solid tumors, such as glioma or pancreatic cancer. The failure to develop effective new agents for the latter diseases has discouraged the development of therapeutics for these cancers. Using glioma as an example, we describe a process toward obtaining more reliable early-stage signals of drug activity and a process toward translating those signals into clinical benefits with more efficient late-stage development. If linked together, these processes should increase the likelihood of benefit in late-stage settings at a lower cost and encourage more drug development for patients with rare and difficult-to-treat cancers.

Next Steps for Immunotherapy in Glioblastoma

Outcomes for glioblastoma (GBM) patients undergoing standard of care treatment remain poor. Here we discuss the portfolio of previously investigated immunotherapies for glioblastoma, including vaccine therapy and checkpoint inhibitors, as well as novel emerging therapeutic approaches. In addition, we explore the factors that potentially influence response to immunotherapy, which should be considered in future research aimed at improving immunotherapy efficacy.

Advanced Imaging Techniques for Newly Diagnosed and Recurrent Gliomas

Management of gliomas following initial diagnosis requires thoughtful presurgical planning followed by regular imaging to monitor treatment response and survey for new tumor growth. Traditional MR imaging modalities such as T1 post-contrast and T2-weighted sequences have long been a staple of tumor diagnosis, surgical planning, and post-treatment surveillance. While these sequences remain integral in the management of gliomas, advances in imaging techniques have allowed for a more detailed characterization of tumor characteristics. Advanced MR sequences such as perfusion, diffusion, and susceptibility weighted imaging, as well as PET scans have emerged as valuable tools to inform clinical decision making and provide a non-invasive way to help distinguish between tumor recurrence and pseudoprogression. Furthermore, these advances in imaging have extended to the operating room and assist in making surgical resections safer. Nevertheless, surgery, chemotherapy, and radiation treatment continue to make the interpretation of MR changes difficult for glioma patients. As analytics and machine learning techniques improve, radiomics offers the potential to be more quantitative and personalized in the interpretation of imaging data for gliomas. In this review, we describe the role of these newer imaging modalities during the different stages of management for patients with gliomas, focusing on the pre-operative, post-operative, and surveillance periods. Finally, we discuss radiomics as a means of promoting personalized patient care in the future.

Toward the Next Generation of High-Grade Glioma Clinical Trials in the Era of Precision Medicine

ABSTRACT

In the era of precision medicine, there is a desire to harness our improved understanding of genomic and molecular underpinnings of gliomas to develop therapies that can be tailored to individual patients and tumors. With the rapid development of novel therapies, there has been a growing need to develop smart clinical trials that are designed to efficiently test promising agents, identify therapies likely to benefit patients, and discard ineffective therapies. We review clinical trial design in gliomas and developments designed to address the unique challenges of precision medicine. To provide an overview of this topic, we examine considerations for endpoints and response assessment, biomarkers, and novel clinical trial designs such as adaptive platform trials in the testing of new therapies for glioma patients.

Clinical Trial Considerations in Neuro-oncology

Clinical trials play a critical role in discovering new treatments, but the path to regulatory approval can be cumbersome and time consuming. Efforts to increase the efficiency and interpretability of clinical trials within the neuro-oncology community have focused on standardization of response assessment, development of consensus guidelines for clinical trial conduct, decentralization of clinical trials, removal of barriers to clinical trial accrual, and re-examination of patient eligibility criteria.

Optimal treatment strategy for adult patients with newly diagnosed glioblastoma: a systematic review and network meta-analysis

To compare the efficacy and safety of treatments based on the Stupp protocol for adult patients with newly diagnosed glioblastoma and to determine the optimal treatment option for patients with different O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation statuses. We estimated hazard ratios (HRs) for overall survival (OS) and odds ratios (ORs) for adverse events of grade 3 or higher (AEs ≥ 3). Twenty-one randomized controlled trials involving 6478 patients treated with 21 different treatment strategies were included. Results of the pooled HRs indicated tumor-treating fields (TTF) combined with the Stupp protocol resulted in the most favorable OS for patients with and without MGMT promoter methylation. Subgroup analyses by the two MGMT promoter statuses indicated that lomustine-temozolomide plus radiotherapy or TTF combination therapy was associated with the best OS for patients with methylated MGMT promoter (HR, 1.03; 95% credible interval [CI], 0.54-1.97), and standard cilengitide combination therapy or TTF combination treatment was associated with the best OS for patients with unmethylated MGMT promoter (HR, 1.05; 95% CI, 0.67-1.64). Regarding AEs ≥ 3, there were no significant differences in pooled ORs. However, Bayesian ranking profiles that demonstrated intensive cilengitide combination therapy and TTF combination therapy have a similar possibility to cause the least toxicity. These results indicated that TTF combination therapy was associated with increased survival, irrespective of the MGMT promoter methylation status, and a relatively tolerated safety profile compared with other combination treatments. The optimal treatment option for glioblastoma patients with different MGMT promoter methylation statuses was different.

Translational Windows in Chordoma: A Target Appraisal

Chordomas are rare tumors that are notoriously refractory to chemotherapy and radiotherapy when radical surgical resection is not achieved or upon recurrence after maximally aggressive treatment. The study of chordomas has been complicated by small patient cohorts and few available model systems due to the rarity of these tumors. Emerging next-generation sequencing technologies have broadened understanding of this disease by implicating novel pathways for possible targeted therapy. Mutations in cell-cycle regulation and chromatin remodeling genes have been identified in chordomas, but their significance remains unknown. Investigation of the immune microenvironment of these tumors suggests that checkpoint protein expression may influence prognosis, and adjuvant immunotherapy may improve patient outcome. Finally, growing evidence supports aberrant growth factor signaling as potential pathogenic mechanisms in chordoma. In this review, we characterize the impact on treatment opportunities offered by the genomic and immunologic landscape of this tumor.

A Phase 0 Trial of Ribociclib in Recurrent Glioblastoma Patients Incorporating a Tumor Pharmacodynamic- and Pharmacokinetic-Guided Expansion Cohort

PURPOSE

CDK4/6-dependent cell-cycle regulation is disrupted in most glioblastomas. This study assesses the central nervous system (CNS) pharmacokinetics and tumor pharmacodynamics of ribociclib, a highly selective CDK4/6 inhibitor, in patients with recurrent glioblastoma.

PATIENTS AND METHODS

Patients with recurrent glioblastoma with intact retinoblastoma protein (RB) expression and CDKN2A deletion or CDK4/6 amplification were treated with ribociclib daily (900 mg) for 5 days before tumor resection. Blood, tumor, and cerebrospinal fluid (CSF) samples were collected, and total and unbound ribociclib concentrations were determined. Pharmacodynamic effects, assessed by RB and FOXM1 phosphorylation, were compared with matched archival tissue. Patients with positive pharmacokinetic and pharmacodynamic effects were enrolled into the expansion cohort for preliminary assessment of progression-free survival (PFS).

RESULTS

Twelve patients were enrolled. The mean unbound ribociclib concentrations in CSF, nonenhancing, and enhancing tumor regions were 0.374 μmol/L, 0.560, and 2.152 μmol/kg, respectively, which were more than 5-fold the in vitro IC50 for inhibition of CDK4/6 (0.04 μmol/L). G1-to-S phase suppression was inferred by decreases in phosphorylation of RB (P < 0.01) and cellular proliferation (P < 0.05). Six of 12 patients were enrolled into the pharmacokinetic/pharmacodynamic-guided expansion cohort and demonstrated a median PFS of 9.7 weeks. Examination of recurrent tumors following monotherapy indicated upregulation of the PI3K/mTOR pathway.

CONCLUSIONS

Ribociclib exhibited good CNS penetration, and target modulation was indicated by inhibition of RB phosphorylation and tumor proliferation. Ribociclib monotherapy showed limited clinical efficacy in patients with recurrent glioblastoma. Combination therapy with CDK4/6 and PI3K/mTOR inhibitors may be explored for treating recurrent glioblastoma.

Long-term trends in glioblastoma survival: implications for historical control groups in clinical trials

Background

Historical controls continue to be used in early-phase brain tumor trials. We aim to show that historical changes in survival trends for glioblastoma (GBM) call into question the use of noncontemporary controls.

Methods

We analyzed data from 46 106 primary GBM cases from the SEER database (1998-2016). We performed trend analysis on survival outcomes (2-year survival probability, median survival, and hazard ratios) and patient characteristics (age, sex, resection extent, and treatment type).

Results

In 2005-2016 (ie, the post-Stupp protocol era), fitting a parameter independently to each year, there was a demonstrable increase in median survival (R² = 0.81, P < .001) and 2-year survival probability (R² = 0.55, P = .006) for GBM. Trend analysis of the hazard ratio showed a significant time-dependent downward trend (R² = 0.62, P = .002). When controlling, via multivariable Cox regression modeling, for age, sex, resection extent, and treatment type, there was a persistent downward trend in hazard ratios with increases in calendar time, especially in the most recent data.

Conclusion

Contemporary GBM patients face a different overall hazard profile from their historical counterparts, which is evident in changes in measures of patient survival and parametric hazard modeling. Though there was a plateau in these measures before 2005 (pre-Stupp protocol), there is no evidence of a new plateau in recent years even when controlling for known prognostic factors (age, sex, resection extent, and treatment type), suggesting that it may be insufficient to match contemporary patients and noncontemporary controls on the basis of these factors.

Multicenter pilot study of radiochemotherapy as first-line treatment for adults with medulloblastoma (NOA-07)

Background

Medulloblastoma in adult patients is rare, with 0.6 cases per million. Prognosis depends on clinical factors and medulloblastoma entity. No prospective data on the feasibility of radiochemotherapy exist. The German Neuro-Oncology Working Group (NOA) performed a prospective descriptive multicenter single-arm phase II trial to evaluate feasibility and toxicity of radio-polychemotherapy.

Methods

The NOA-07 trial combined craniospinal irradiation with vincristine, followed by 8 cycles of cisplatin, lomustine, and vincristine. Adverse events, imaging and progression patterns, histological and genetic markers, health-related quality of life (HRQoL), and cognition were evaluated. Primary endpoint was the rate of toxicity-related treatment terminations after 4 chemotherapy cycles, and the toxicity profile. The feasibility goal was reached if at least 45% of patients received at least 4 cycles of maintenance chemotherapy.

Results

Thirty patients were evaluable. Each 50% showed classic and desmoplastic/nodular histology. Sixty-seven percent were classified into the sonic hedgehog (SHH) subgroup without TP53 alterations, 13% in wingless (WNT), and 17% in non-WNT/non-SHH. Four cycles of chemotherapy were feasible in the majority (n = 21; 70.0%). Hematological side effects and polyneuropathy were prevalent toxicities. During the active treatment period, HRQoL and verbal fluency improved significantly. The 3-year event-free survival rate was 66.6% at the time of databank lock.

Conclusions

Radio-polychemotherapy did lead to considerable toxicity and a high amount of dose reductions throughout the first 4 chemotherapy cycles that may affect efficacy. Thus, we propose frequent patient surveillance using this regimen. Modifications of the regimen may increase feasibility of radio-polychemotherapy of adult patients with medulloblastoma.

Dacomitinib: an investigational drug for the treatment of glioblastoma

INTRODUCTION

Standard treatment of newly diagnosed glioblastoma (GB) is surgery with radiotherapy and temozolomide, but tumors will recur with a median overall survival of only 15 months. It seems imperative to explore new possibilities of treatment based on targetable alterations known to be present in GB. Among others, Epidermal Growth Factor Receptor or EGFR (HER1) mutations or amplifications are the most prevalent alterations in GB. In fact, around 40% of GB cases show amplification of EGFR gene, and half of these patients carry the EGFRvIII mutation, a deletion that generates a continuous activation of the tyrosine kinase domain of the receptor. Areas covered: We review the current knowledge about Dacomitinib, an oral, irreversible, second-generation, pan-HER tyrosine kinase inhibitor, in the treatment of glioblastoma. Dacomitinib has noteworthy antiglioma activity in preclinical models and has been tested in one phase II trial in patients with recurrent GB with EGFR amplification. Expert opinion: Despite the poor global results of Dacomitinib in recurrent GB shown in a phase II trial, some patients had a significant benefit. Therefore, it is necessary to improve the knowledge about the mechanisms of failure or resistance to EGFR inhibitors in GB.

Phase I/II trial of vorinostat combined with temozolomide and radiation therapy for newly diagnosed glioblastoma: results of Alliance N0874/ABTC 02

Background

Vorinostat, a histone deacetylase (HDAC) inhibitor, has shown radiosensitizing properties in preclinical studies. This open-label, single-arm trial evaluated the maximum tolerated dose (MTD; phase I) and efficacy (phase II) of vorinostat combined with standard chemoradiation in newly diagnosed glioblastoma.

Methods

Patients received oral vorinostat (300 or 400 mg/day) on days 1-5 weekly during temozolomide chemoradiation. Following a 4- to 6-week rest, patients received up to 12 cycles of standard adjuvant temozolomide and vorinostat (400 mg/day) on days 1-7 and 15-21 of each 28-day cycle. Association between vorinostat response signatures and progression-free survival (PFS) and overall survival (OS) was assessed based on RNA sequencing of baseline tumor tissue.

Results

Phase I and phase II enrolled 15 and 107 patients, respectively. The combination therapy MTD was vorinostat 300 mg/day and temozolomide 75 mg/m2/day. Dose-limiting toxicities were grade 4 neutropenia and thrombocytopenia and grade 3 aspartate aminotransferase elevation, hyperglycemia, fatigue, and wound dehiscence. The primary efficacy endpoint in the phase II cohort, OS rate at 15 months, was 55.1% (median OS 16.1 mo), and consequently, the study did not meet its efficacy objective. Most common treatment-related grade 3/4 toxicities in the phase II component were lymphopenia (32.7%), thrombocytopenia (28.0%), and neutropenia (21.5%). RNA expression profiling of baseline tumors (N = 76) demonstrated that vorinostat resistance (sig-79) and sensitivity (sig-139) signatures had a reverse and positive association with OS/PFS, respectively.

Conclusions

Vorinostat combined with standard chemoradiation had acceptable tolerability in newly diagnosed glioblastoma. Although the primary efficacy endpoint was not met, vorinostat sensitivity and resistance signatures could facilitate patient selection in future trials.

Clinical trial endpoints for patients with gliomas

Malignant glioma represents a diverse set of molecularly heterogeneous diseases. Few therapeutic agents have been approved despite decades of clinical trials research and pre-clinical investigation. Attempts to refine neuroimaging criteria and recent discovery of the genomic profiles linking tumor subsets to survival outcomes have spurred discussion on a variety of new approaches in clinical trial design and relevant endpoints. Here we focus on those endpoints in clinical trial design for patients with primary glioma and related issues still to be resolved.

Response Assessment in Neuro-Oncology Clinical Trials

Development of novel therapies for CNS tumors requires reliable assessment of response and progression. This requirement has been particularly challenging in neuro-oncology for which contrast enhancement serves as an imperfect surrogate for tumor volume and is influenced by agents that affect vascular permeability, such as antiangiogenic therapies. In addition, most tumors have a nonenhancing component that can be difficult to accurately quantify. To improve the response assessment in neuro-oncology and to standardize the criteria that are used for different CNS tumors, the Response Assessment in Neuro-Oncology (RANO) working group was established. This multidisciplinary international working group consists of neuro-oncologists, medical oncologists, neuroradiologists, neurosurgeons, radiation oncologists, neuropsychologists, and experts in clinical outcomes assessments, working in collaboration with government and industry to enhance the interpretation of clinical trials. The RANO working group was originally created to update response criteria for high- and low-grade gliomas and to address such issues as pseudoresponse and nonenhancing tumor progression from antiangiogenic therapies, and pseudoprogression from radiochemotherapy. RANO has expanded to include working groups that are focused on other tumors, including brain metastases, leptomeningeal metastases, spine tumors, pediatric brain tumors, and meningiomas, as well as other clinical trial end points, such as clinical outcomes assessments, seizures, corticosteroid use, and positron emission tomography imaging. In an effort to standardize the measurement of neurologic function for clinical assessment, the Neurologic Assessment in Neuro-Oncology scale was drafted. Born out of a workshop conducted by the Jumpstarting Brain Tumor Drug Development Coalition and the US Food and Drug Administration, a standardized brain tumor imaging protocol now exists to reduce variability and improve reliability. Efforts by RANO have been widely accepted and are increasingly being used in neuro-oncology trials, although additional refinements will be needed.

Current status and perspectives of interventional clinical trials for glioblastoma - analysis of ClinicalTrials.gov

The records of 208.777 (100%) clinical trials registered at ClinicalTrials.gov were downloaded on the 19th of February 2016. Phase II and III trials including patients with glioblastoma were selected for further classification and analysis. Based on the disease settings, trials were classified into three groups: newly diagnosed glioblastoma, recurrent disease and trials with no differentiation according to disease setting. Furthermore, we categorized trials according to the experimental interventions, the primary sponsor, the source of financial support and trial design elements. Trends were evaluated using the autoregressive integrated moving average model. Two hundred sixteen (0.1%) trials were selected for further analysis. Academic centers (investigator initiated trials) were recorded as primary sponsors in 56.9% of trials, followed by industry 25.9%. Industry was the leading source of monetary support for the selected trials in 44.4%, followed by 25% of trials with primarily academic financial support. The number of newly initiated trials between 2005 and 2015 shows a positive trend, mainly through an increase in phase II trials, whereas phase III trials show a negative trend. The vast majority of trials evaluate forms of different systemic treatments (91.2%). In total, one hundred different molecular entities or biologicals were identified. Of those, 60% were involving drugs specifically designed for central nervous system malignancies. Trials that specifically address radiotherapy, surgery, imaging and other therapeutic or diagnostic methods appear to be rare. Current research in glioblastoma is mainly driven or sponsored by industry, academic medical oncologists and neuro-oncologists, with the majority of trials evaluating forms of systemic therapies. Few trials reach phase III. Imaging, radiation therapy and surgical procedures are underrepresented in current trials portfolios. Optimization in research portfolio for glioblastoma is needed.

Advances in the molecular genetics of gliomas - implications for classification and therapy

Genome-wide molecular-profiling studies have revealed the characteristic genetic alterations and epigenetic profiles associated with different types of gliomas. These molecular characteristics can be used to refine glioma classification, to improve prediction of patient outcomes, and to guide individualized treatment. Thus, the WHO Classification of Tumours of the Central Nervous System was revised in 2016 to incorporate molecular biomarkers - together with classic histological features - in an integrated diagnosis, in order to define distinct glioma entities as precisely as possible. This paradigm shift is markedly changing how glioma is diagnosed, and has important implications for future clinical trials and patient management in daily practice. Herein, we highlight the developments in our understanding of the molecular genetics of gliomas, and review the current landscape of clinically relevant molecular biomarkers for use in classification of the disease subtypes. Novel approaches to the genetic characterization of gliomas based on large-scale DNA-methylation profiling and next-generation sequencing are also discussed. In addition, we illustrate how advances in the molecular genetics of gliomas can promote the development and clinical translation of novel pathogenesis-based therapeutic approaches, thereby paving the way towards precision medicine in neuro-oncology.

Response Assessment in Neuro-Oncology Criteria and Clinical Endpoints

The Response Assessment in Neuro-Oncology (RANO) Working Group is an international multidisciplinary group whose goal is to improve response criteria and define endpoints for neuro-oncology trials. The RANO criteria for high-grade gliomas attempt to address the issues of pseudoprogression, pseudoresponse, and nonenhancing tumor progression. Incorporation of advanced MR imaging may eventually help improve the ability of these criteria to define enhancing and nonenhancing disease better. The RANO group has also developed criteria for neurologic response and evaluation of patients receiving immunologic therapies. RANO criteria have been developed for brain metastases and are in progress for meningiomas, leptomeningeal disease, spinal tumors, and pediatric tumors.

Evaluation of pseudoprogression rates and tumor progression patterns in a phase III trial of bevacizumab plus radiotherapy/temozolomide for newly diagnosed glioblastoma

BACKGROUND

Evaluation of glioblastoma disease status may be complicated by treatment-induced changes and discordance between enhancing and nonenhancing MRI. Exploratory analyses are presented (prospectively assessed pseudoprogression and therapy-related tumor pattern changes) from the AVAglio trial (bevacizumab or placebo plus radiotherapy/temozolomide for newly diagnosed glioblastoma).

METHODS

MRI was done every 8 weeks (beginning 4 wk after chemoradiotherapy) using prespecified and standardized T1 and T2 protocols. Progressive disease (PD) at 10 weeks was reconfirmed at 18 weeks to distinguish pseudoprogression. Progression-free survival (PFS), excluding cases of confirmed pseudoprogression, was assessed (post-hoc/exploratory). Tumor progression patterns were determined at each disease assessment/PD (prespecified/exploratory).

RESULTS

Of patients with PD in the bevacizumab and placebo arms, 143/354 (40.4%) and 155/387 (40.1%), respectively, had PD due to contrast-enhancing lesions, and 51/354 (14.4%) and 53/387 (13.7%) had PD due to nonenhancing lesions. Of all patients in the bevacizumab arm (n = 458), 2.2% had confirmed pseudoprogression versus 9.3% in the placebo arm (n = 463). Baseline characteristics did not differ between patients with/without pseudoprogression (including for MGMT status). Excluding confirmed pseudoprogression, PFS (hazard ratio: 0.65, 95% CI: 0.56-0.75; P < .0001, bevacizumab vs placebo) was comparable to the intent-to-treat population. At PD, most patients had the same tumor focus (local/multifocal, >84%) and infiltrative profile (>88%) as at baseline; no shift to a diffuse or multifocal phenotype was observed.

CONCLUSIONS

Pseudoprogression complicated progression assessment in a small but relevant number of patients but had negligible impact on PFS. Bevacizumab did not appear to adversely impact tumor progression patterns.

Creating clinical trial designs that incorporate clinical outcome assessments

Clinical outcome assessments (COAs) are increasingly being used in determining the efficacy of new treatment regimens. This was typified in the recent use of a symptom-based instrument combined with an organ-based measure of response for the approval of ruxolitinib in myelofibrosis. There are challenges in incorporating these COAs into clinical trials, including designating the level of priority, incorporating these measures into a combined or composite endpoint, and dealing with issues related to compliance and interpretation of results accounting for missing data. This article describes the results of a recent panel discussion that attempted to address these issues and provide guidance to the incorporation of COAs into clinical trials, including novel statistical designs, so that the testing of new treatments in patients with cancers of the central nervous system can incorporate these important clinical endpoints.

Bevacizumab and temozolomide versus temozolomide alone as neoadjuvant treatment in unresected glioblastoma: the GENOM 009 randomized phase II trial

We sought to determine the impact of bevacizumab on reduction of tumor size prior to chemoradiotherapy in unresected glioblastoma patients. Patients were randomized 1:1 to receive temozolomide (TMZ arm) or temozolomide plus bevacizumab (TMZ + BEV arm). In both arms, neoadjuvant treatment was temozolomide (85 mg/m(2), days 1-21, two 28-day cycles), concurrent radiation plus temozolomide, and six cycles of adjuvant temozolomide. In the TMZ + BEV arm, bevacizumab (10 mg/kg) was added on days 1 and 15 of each neoadjuvant cycle and on days 1, 15 and 30 of concurrent treatment. The primary endpoint was investigator-assessed response to neoadjuvant treatment. Secondary endpoints included progression-free survival (PFS), overall survival (OS), and the impact on outcome of MGMT methylation in tumor and serum. One hundred and two patients were included; 43 in the TMZ arm and 44 in the TMZ + BEV arm were evaluable for response. Results favored the TMZ + BEV arm in terms of objective response (3 [6.7 %] vs. 11 [22.9 %]; odds ratio 4.2; P = 0.04). PFS and OS were longer in the TMZ + BEV arm, though the difference did not reach statistical significance. MGMT methylation in tumor, but not in serum, was associated with outcome. More patients experienced toxicities in the TMZ + BEV than in the TMZ arm (P = 0.06). The combination of bevacizumab plus temozolomide is more active than temozolomide alone and may well confer benefit in terms of tumor shrinkage in unresected patients albeit at the expense of greater toxicity.

Response Assessment in Neuro-Oncology (RANO): more than imaging criteria for malignant glioma

The introduction of antiangiogenic therapies for the treatment of malignant glioma and the effect of these agents on standard imaging studies were the stimuli for forming a small group of investigators to critically evaluate the limitations of the Macdonald criteria in assessing response to treatment. The initial goal of this group was to highlight the challenges in accurately determining the efficacy of therapeutic interventions for malignant glioma and to develop new criteria that could be implemented in clinical care as well as in the design and conduct of clinical trials. This initial Response Assessment in Neuro-Oncology (RANO) effort started in 2008 and over the last 7 years, it has expanded to include a critical review of response assessment across several tumor types as well as endpoint selection and trial design to improve outcome criteria for neuro-oncological trials. In this paper, we review the overarching principles of the RANO initiative and the efforts to date. We also highlight the diverse and expanding efforts of the multidisciplinary groups of investigators who have volunteered their time as part of this endeavor.

What next for newly diagnosed glioblastoma?

Glioblastoma is the most common primary brain tumor in adults. Despite current multimodality treatment including surgical resection and temozolomide-based chemoradiotherapy, median survival is only 14-16 months. Characterization of molecular alterations in glioblastoma has identified prognostic subgroups and therapeutic opportunities for clinical trials across glioblastoma subsets. Following a number of negative Phase III trials testing temozolomide dose intensification and angiogenesis inhibition, recent interim analysis data indicate survival prolongation with use of a device (Optune™) delivering alternating electrical field therapy in newly diagnosed glioblastoma patients. In this review, we present an overview of the data supporting the current standard of care and discuss novel experimental therapies in early and late phase clinical testing including devices, small molecule drugs, angiogenesis inhibitors, oncolytic virotherapy and immunotherapy.

Glioma

Gliomas are primary brain tumours that are thought to derive from neuroglial stem or progenitor cells. On the basis of their histological appearance, they have been traditionally classified as astrocytic, oligodendroglial or ependymal tumours and assigned WHO grades I-IV, which indicate different degrees of malignancy. Tremendous progress in genomic, transcriptomic and epigenetic profiling has resulted in new concepts of classifying and treating gliomas. Diffusely infiltrating gliomas in adults are now separated into three overarching tumour groups with distinct natural histories, responses to treatment and outcomes: isocitrate dehydrogenase (IDH)-mutant, 1p/19q co-deleted tumours with mostly oligodendroglial morphology that are associated with the best prognosis; IDH-mutant, 1p/19q non-co-deleted tumours with mostly astrocytic histology that are associated with intermediate outcome; and IDH wild-type, mostly higher WHO grade (III or IV) tumours that are associated with poor prognosis. Gliomas in children are molecularly distinct from those in adults, the majority being WHO grade I pilocytic astrocytomas characterized by circumscribed growth, favourable prognosis and frequent BRAF gene fusions or mutations. Ependymal tumours can be molecularly subdivided into distinct epigenetic subgroups according to location and prognosis. Although surgery, radiotherapy and alkylating agent chemotherapy are still the mainstay of treatment, individually tailored strategies based on tumour-intrinsic dominant signalling pathways and antigenic tumour profiles may ultimately improve outcome. For an illustrated summary of this Primer, visit: http://go.nature.com/TXY7Ri.

Facing the future of brain tumor clinical research

This edition of CCR Focus provides critical reviews of several important areas in the field, including the application of findings from genomic investigations of brain tumors to improve diagnosis, clinical trial design, and ultimately optimizing individual patient treatment. Another article is a critical review provided by experts in the field that discusses the recent clinical trials using angiogenesis inhibitors, possible explanations for the results, and how to move forward. There is a concise discussion of the application of immunotherapy to brain tumors by key investigators in this field, reflecting the potential opportunities as well as the disease-specific challenges. Finally, leading pediatric brain tumor investigators provide an overview of the field and insights about the recent seminal discoveries in two pediatric brain tumors, supporting the paradigm that laboratory investigations lead to more precise diagnosis, prognosis, and ultimately better treatment. Herein, an overview of the recent advances and challenges in the area of clinical and translational brain tumor research is provided to set the stage for the contributions that follow.

A Multicenter, Phase II, Randomized, Noncomparative Clinical Trial of Radiation and Temozolomide with or without Vandetanib in Newly Diagnosed Glioblastoma Patients

PURPOSE

Vandetanib, a tyrosine kinase inhibitor of KDR (VEGFR2), EGFR, and RET, may enhance sensitivity to chemotherapy and radiation. We conducted a randomized, noncomparative, phase II study of radiation (RT) and temozolomide with or without vandetanib in patients with newly diagnosed glioblastoma (GBM).

EXPERIMENTAL DESIGN

We planned to randomize a total of 114 newly diagnosed GBM patients in a ratio of 2:1 to standard RT and temozolomide with (76 patients) or without (38 patients) vandetanib 100 mg daily. Patients with age ≥ 18 years, Karnofsky performance status (KPS) ≥ 60, and not on enzyme-inducing antiepileptics were eligible. Primary endpoint was median overall survival (OS) from the date of randomization. Secondary endpoints included median progression-free survival (PFS), 12-month PFS, and safety. Correlative studies included pharmacokinetics as well as tissue and serum biomarker analysis.

RESULTS

The study was terminated early for futility based on the results of an interim analysis. We enrolled 106 patients (36 in the RT/temozolomide arm and 70 in the vandetanib/RT/temozolomide arm). Median OS was 15.9 months [95% confidence interval (CI), 11.0-22.5 months] in the RT/temozolomide arm and 16.6 months (95% CI, 14.9-20.1 months) in the vandetanib/RT/temozolomide (log-rank P = 0.75).

CONCLUSIONS

The addition of vandetanib at a dose of 100 mg daily to standard chemoradiation in patients with newly diagnosed GBM or gliosarcoma was associated with potential pharmacodynamic biomarker changes and was reasonably well tolerated. However, the regimen did not significantly prolong OS compared with the parallel control arm, leading to early termination of the study.

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.

Brain Malignancy Steering Committee clinical trials planning workshop: report from the Targeted Therapies Working Group

Glioblastoma is the most common primary brain malignancy and is associated with poor prognosis despite aggressive local and systemic therapy, which is related to a paucity of viable treatment options in both the newly diagnosed and recurrent settings. Even so, the rapidly increasing number of targeted therapies being evaluated in oncology clinical trials offers hope for the future. Given the broad range of possibilities for future trials, the Brain Malignancy Steering Committee convened a clinical trials planning meeting that was held at the Udvar-Hazy Center in Chantilly, Virginia, on September 19 and 20, 2013. This manuscript reports the deliberations leading up to the event from the Targeted Therapies Working Group and the results of the meeting.

The use of phase 2 interim analysis to expedite drug development decisions

PURPOSE

To expedite drug development, we propose a two-step decision-making process that utilizes interim efficacy results from a comparative phase 2 trial to determine whether to accelerate subsequent phase 3 preparations, and final analysis to ultimately determine whether to conduct phase 3 testing.

METHODS

The operational characteristics of this process were evaluated by modeling simulated data of oncology trials and retrospectively analyzing data from historical comparative phase 2 trials. Progression-free survival (PFS) was used as the primary endpoint; the estimated PFS hazard ratios (HRs) of ≤0.60 at interim and of ≤0.65 at final analysis favoring the experimental arm were defined as positive results. The conditional probability of achieving a target PFS HR at final analysis, based on observed interim results, was also estimated by imputing post-interim data with and without the proportional hazard assumption.

RESULTS

Simulations of phase 2 trials showed that estimated interim PFS HRs correlated with estimated final PFS HRs, with reasonably low false-positive rates for supporting phase 3 "go" decisions at interim. Using observed historical data, decisions based on interim PFS analyses also matched final phase 3 "go" and "no-go" decisions with a false-positive rate of 16.7% (2 of 12 trials) and a false-negative rate of 9.4% (3 of 32 trials). Analytical modeling accurately predicted final PFS HRs from observed interim data when accounting for appropriate underlying assumptions.

CONCLUSIONS

The results support the usefulness of a two-step decision-making process that utilizes interim phase 2 results to reduce the interval between phase 2 completion and phase 3 initiation.

Enzastaurin before and concomitant with radiation therapy, followed by enzastaurin maintenance therapy, in patients with newly diagnosed glioblastoma without MGMT promoter hypermethylation

BACKGROUND

This study's primary objective was evaluation of the progression-free survival rate at 6 months (PFS-6) in patients with newly diagnosed glioblastoma without O(6)-methylguanine-DNA-methyltransferase (MGMT) promoter hypermethylation postsurgically treated with enzastaurin before and concomitantly with radiation therapy, followed by enzastaurin maintenance therapy. PFS-6 of at least 55% was set to be relevant compared with the data of the EORTC 26981/22981 NCIC CE.3 trial.

METHODS

Adult patients with a life expectancy of at least 12 weeks who were newly diagnosed with a histologically proven supratentorial glioblastoma without MGMT promoter hypermethylation were eligible. Patients were treated with enzastaurin prior to, concomitantly with, and after standard partial brain radiotherapy. Here we report on a multicenter, open-label, uncontrolled phase II study of patients with newly diagnosed glioblastoma without MGMT promoter hypermethylation treated with enzastaurin and radiation therapy within 4 study periods.

RESULTS

PFS-6 was 53.6% (95% confidence interval [CI]: 39.8-65.6). The median overall survival was 15.0 months (95% CI: 11.9-17.9) for all patients, 3.9 months (95% CI: 0.8-9.0) for patients with biopsy, 15.4 months (95% CI: 10.1-17.9) for patients with partial resection, and 18.9 months (95% CI: 13.9-28.5) for patients with complete resection. The safety profile in this study was as expected from previous trials, and the therapy was well tolerated.

CONCLUSIONS

PFS-6 missed the primary planned outcome of 55%. The secondary exploratory analysis according to resection status of the different subgroups of patients with biopsies, partial resection, and complete resection demonstrates the strong prognostic influence of resection on overall survival.

Biomarker-based adaptive trials for patients with glioblastoma--lessons from I-SPY 2

The traditional clinical trials infrastructure may not be ideally suited to evaluate the numerous therapeutic hypotheses that result from the increasing number of available targeted agents combined with the various methodologies to molecularly subclassify patients with glioblastoma. Additionally, results from smaller screening studies are rarely translated to successful larger confirmatory studies, potentially related to a lack of efficient control arms or the use of unvalidated surrogate endpoints. Streamlining clinical trials and providing a flexible infrastructure for biomarker development is clearly needed for patients with glioblastoma. The experience developing and implementing the I-SPY studies in breast cancer may serve as a guide to developing such trials in neuro-oncology.

Incorporation of prognostic and predictive factors into glioma clinical trials

Treatment of brain tumors is increasingly informed by biomarkers that predict patient prognosis and response to therapy. While this progress represents a great opportunity for the field of neuro-oncology, it also presents significant challenges. Biomarkers are not straightforward to identify, and previously used clinical trial paradigms are poorly suited to the task of identifying treatments effective only in selected subsets of patients. Unless investigators adapt new tools and procedures that better account for the biological diversity of gliomas, future clinical trials run the dual risk of missing important treatment effects and exposing patients to interventions destined to prove ineffective for their tumors. In this article, we will review the progress made in the past decade with respect to biomarkers in neuro-oncology, address barriers to ongoing progress, and discuss clinical trial designs that may prove useful in moving neuro-oncology fully into the era of personalized medicine.

Phase II trial of upfront bevacizumab and temozolomide for unresectable or multifocal glioblastoma

Patients with unresectable glioblastomas have a poor prognosis, with median survival of 6–10 months. We conducted a phase II trial of upfront 5-day temozolomide (TMZ) and bevacizumab (BV) in patients with newly diagnosed unresectable or multifocal glioblastoma. Patients received up to four cycles of TMZ at 200 mg/m² on days 1–5, and BV at 10 mg/kg on days 1 and 15 of a 28-day cycle. Brain magnetic resonance imaging (MRI) was performed monthly. Therapy was continued as long as there was no tumor progression, grade 4 nonhematologic toxicity, or recurrent grade 4 hematologic toxicity after dose reduction. The primary end point was best tumor response as measured on MRI. Forty-one patients were accrued over 12 months; 39 had a full set of MRI scans available for evaluation. Assessment for best radiographic responses was as follows: partial responses in 24.4%, stable disease in 68.3%, and progressive disease in 2.4%. Treatment-related toxicities included seven grade 4 toxicities and one grade 5 toxicity (myocardial infarction). From this study, it was concluded that an upfront regimen of TMZ and BV for unresectable glioblastoma was well tolerated and provided a significant level of disease stabilization. Therapeutic toxicities were consistent with those seen in the adjuvant setting using these agents. The upfront approach to treatment of glioblastoma in the unresectable population warrants further investigation in randomized controlled phase III trials.

Diagnostic and therapeutic avenues for glioblastoma: no longer a dead end?

Glioblastomas are heterogeneous neoplasms that are driven by complex signalling pathways, and are among the most aggressive and challenging cancers to treat. Despite standard treatment with resection, radiation and chemotherapy, the prognosis of patients with glioblastomas remains poor. An increasing understanding of the molecular pathogenesis of glioblastomas has stimulated the development of novel therapies, including the use of molecular-targeted agents. Identification and validation of diagnostic, prognostic and predictive biomarkers has led to the advancement of clinical trial design, and identification of glioblastoma subgroups with a more-favourable prognosis and response to therapy. In this Review, we discuss common molecular alterations relevant to the biology of glioblastomas, targeted, antiangiogenic and immunotherapies that have impacted on the treatment of this disease, and the challenges and pitfalls associated with these therapies. In addition, we emphasize current biomarkers relevant to the management of patients with glioblastoma.