Jeffrey J. Olson

A phase II study of temozolomide vs. procarbazine in patients with glioblastoma multiforme at first relapse.

A randomized, multicentre, open-label, phase II study compared temozolomide (TMZ), an oral second-generation alkylating agent, and procarbazine (PCB) in 225 patients with glioblastoma multiforme at first relapse. Primary objectives were to determine progression-free survival (PFS) at 6 months and safety for TMZ and PCB in adult patients who failed conventional treatment. Secondary objectives were to assess overall survival and health-related quality of life (HRQL). TMZ was given orally at 200 mg/m2/day or 150 mg/m2/day (prior chemotherapy) for 5 days, repeated every 28 days. PCB was given orally at 150 mg/m2/day or 125 mg/m2/day (prior chemotherapy) for 28 days, repeated every 56 days. HRQL was assessed using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30 [+3]) and the Brain Cancer Module 20 (BCM20). The 6-month PFS rate for patients who received TMZ was 21%, which met the protocol objective. The 6-month PFS rate for those who received PCB was 8% (P = 0.008, for the comparison). Overall PFS significantly improved with TMZ, with a median PFS of 12.4 weeks in the TMZ group and 8.32 weeks in the PCB group (P = 0.0063). The 6-month overall survival rate for TMZ patients was 60% vs. 44% for PCB patients (P = 0.019). Freedom from disease progression was associated with maintenance of HRQL, regardless of treatment received. TMZ had an acceptable safety profile; most adverse events were mild or moderate in severity.

Exciting New Advances in Neuro-Oncology The Avenue to a Cure for Malignant Glioma

Malignant gliomas are the most common and deadly brain tumors. Nevertheless, survival for patients with glioblastoma, the most aggressive glioma, although individually variable, has improved from an average of 10 months to 14 months after diagnosis in the last 5 years due to improvements in the standard of care. Radiotherapy has been of key importance to the treatment of these lesions for decades, and the ability to focus the beam and tailor it to the irregular contours of brain tumors and minimize the dose to nearby critical structures with intensity‐modulated or image‐guided techniques has improved greatly. Temozolomide, an alkylating agent with simple oral administration and a favorable toxicity profile, is used in conjunction with and after radiotherapy. Newer surgical techniques, such as fluorescence‐guided resection and neuroendoscopic approaches, have become important in the management of malignant gliomas. Furthermore, new discoveries are being made in basic and translational research, which are likely to improve this situation further in the next 10 years. These include agents that block 1 or more of the disordered tumor proliferation signaling pathways, and that overcome resistance to already existing treatments. Targeted therapies such as antiangiogenic therapy with antivascular endothelial growth factor antibodies (bevacizumab) are finding their way into clinical practice. Large‐scale research efforts are ongoing to provide a comprehensive understanding of all the genetic alterations and gene expression changes underlying glioma formation. These have already refined the classification of glioblastoma into 4 distinct molecular entities that may lead to different treatment regimens. The role of cancer stem‐like cells is another area of active investigation. There is definite hope that by 2020, new cocktails of drugs will be available to target the key molecular pathways involved in gliomas and reduce their mortality and morbidity, a positive development for patients, their families, and medical professionals alike. CA Cancer J Clin 2010;60:166–193.

The Brain Tumor Cooperative Group NIH Trial 87-01: A randomized comparison of surgery, external radiotherapy, and carmustine versus surgery, interstitial radiotherapy boost, external radiation therapy, and carmustine

OBJECTIVE The objective of the Brain Tumor Cooperative Group NIH Trial 87-01 trial was to investigate the effect of additional implanted radiation therapy in newly diagnosed patients with pathologically confirmed malignant gliomas. METHODS The study involved a randomized comparison of surgery, external beam radiotherapy, and carmustine (BCNU) versus surgery, external beam therapy, interstitial radiotherapy boost, and BCNU in newly diagnosed malignant gliomas. (125)I was chosen as best suited for this effort because it allowed preimplantation planning and postimplantation quality assurance review. Two hundred ninety-nine patients met the eligibility criteria and were randomized into the two arms of the study between December 1987 and April 1994. Follow-up continued for an additional 3 years. Twenty-nine patients were identified as having committed protocol violations and were excluded, resulting in 270 subjects in the Valid Study Group. One hundred thirty-seven patients received external beam radiation and BCNU, and 133 underwent the (125)I implantation plus external beam radiation and BCNU therapy. RESULTS The overall median survival for the Valid Study Group was 64.3 weeks. The median survival for patients receiving additional therapy of (125)I was 68.1 weeks, and median survival for those receiving only external beam radiation and BCNU was 58.8 weeks. The cumulative proportion surviving between the two treatment groups was not statistically significantly different (log-rank test, P = 0.101). As in other studies in the literature, age, Karnofsky score, and pathology were predictors of mortality. Additional analyses incorporating an adjustment for these prognostic variables, either in a stratified analysis or Cox proportional hazards model, did not result in statistically significant differences in the cumulative proportion of patients surviving between the two treatment groups. CONCLUSION We conclude that there is no long-term survival advantage of increased radiation dose with (125)I seeds in newly diagnosed glioma patients.

The role of whole brain radiation therapy in the management of newly diagnosed brain metastases: a systematic review and evidence-based clinical practice guideline

AbstractShould whole brain radiation therapy (WBRT) be used as the sole therapy in patients with newly-diagnosed, surgically accessible, single brain metastases, compared with WBRT plus surgical resection, and in what clinical settings?Target population This recommendation applies to adults with newly diagnosed single brain metastases amenable to surgical resection; however, the recommendation does not apply to relatively radiosensitive tumors histologies (i.e., small cell lung cancer, leukemia, lymphoma, germ cell tumors and multiple myeloma). RecommendationSurgical resection plus WBRT versus WBRT aloneLevel 1 Class I evidence supports the use of surgical resection plus post-operative WBRT, as compared to WBRT alone, in patients with good performance status (functionally independent and spending less than 50% of time in bed) and limited extra-cranial disease. There is insufficient evidence to make a recommendation for patients with poor performance scores, advanced systemic disease, or multiple brain metastases. If WBRT is used, is there an optimal dosing/fractionation schedule?Target population This recommendation applies to adults with newly diagnosed brain metastases. RecommendationLevel 1 Class I evidence suggests that altered dose/fractionation schedules of WBRT do not result in significant differences in median survival, local control or neurocognitive outcomes when compared with “standard” WBRT dose/fractionation. (i.e., 30 Gy in 10 fractions or a biologically effective dose (BED) of 39 Gy10). If WBRT is used, what impact does tumor histopathology have on treatment outcomes?Target population This recommendation applies to adults with newly diagnosed brain metastases. Recommendation Given the extremely limited data available, there is insufficient evidence to support the choice of any particular dose/fractionation regimen based on histopathology.The following question is fully addressed in the surgery guideline paper within this series by Kalkanis et al. Given that the recommendation resulting from the systematic review of the literature on this topic is also highly relevant to the discussion of the role of WBRT in the management of brain metastases, this recommendation has been included below. Does the addition of WBRT after surgical resection improve outcomes when compared with surgical resection alone?Target population This recommendation applies to adults with newly diagnosed single brain metastases amenable to surgical resection. RecommendationSurgical resection plus WBRT versus surgical resection aloneLevel 1 Surgical resection followed by WBRT represents a superior treatment modality, in terms of improving tumor control at the original site of the metastasis and in the brain overall, when compared to surgical resection alone.

Multiplex digital PCR: breaking the one target per color barrier of quantitative PCR

Quantitative polymerase chain reactions (qPCR) based on real-time PCR constitute a powerful and sensitive method for the analysis of nucleic acids. However, in qPCR, the ability to multiplex targets using differently colored fluorescent probes is typically limited to 4-fold by the spectral overlap of the fluorophores. Furthermore, multiplexing qPCR assays requires expensive instrumentation and most often lengthy assay development cycles. Digital PCR (dPCR), which is based on the amplification of single target DNA molecules in many separate reactions, is an attractive alternative to qPCR. Here we report a novel and easy method for multiplexing dPCR in picolitre droplets within emulsions-generated and read out in microfluidic devices-that takes advantage of both the very high numbers of reactions possible within emulsions (>10(6)) as well as the high likelihood that the amplification of only a single target DNA molecule will initiate within each droplet. By varying the concentration of different fluorogenic probes of the same color, it is possible to identify the different probes on the basis of fluorescence intensity. Adding multiple colors increases the number of possible reactions geometrically, rather than linearly as with qPCR. Accurate and precise copy numbers of up to sixteen per cell were measured using a model system. A 5-plex assay for spinal muscular atrophy was demonstrated with just two fluorophores to simultaneously measure the copy number of two genes (SMN1 and SMN2) and to genotype a single nucleotide polymorphism (c.815A>G, SMN1). Results of a pilot study with SMA patients are presented.

Poor drug distribution as a possible explanation for the results of the PRECISE trial

OBJECT Convection-enhanced delivery (CED) is a novel intracerebral drug delivery technique with considerable promise for delivering therapeutic agents throughout the CNS. Despite this promise, Phase III clinical trials employing CED have failed to meet clinical end points. Although this may be due to inactive agents or a failure to rigorously validate drug targets, the authors have previously demonstrated that catheter positioning plays a major role in drug distribution using this technique. The purpose of the present work was to retrospectively analyze the expected drug distribution based on catheter positioning data available from the CED arm of the PRECISE trial. METHODS Data on catheter positioning from all patients randomized to the CED arm of the PRECISE trial were available for analyses. BrainLAB iPlan Flow software was used to estimate the expected drug distribution. RESULTS Only 49.8% of catheters met all positioning criteria. Still, catheter positioning score (hazard ratio 0.93, p = 0.043) and the number of optimally positioned catheters (hazard ratio 0.72, p = 0.038) had a significant effect on progression-free survival. Estimated coverage of relevant target volumes was low, however, with only 20.1% of the 2-cm penumbra surrounding the resection cavity covered on average. Although tumor location and resection cavity volume had no effect on coverage volume, estimations of drug delivery to relevant target volumes did correlate well with catheter score (p < 0.003), and optimally positioned catheters had larger coverage volumes (p < 0.002). Only overall survival (p = 0.006) was higher for investigators considered experienced after adjusting for patient age and Karnofsky Performance Scale score. CONCLUSIONS The potential efficacy of drugs delivered by CED may be severely constrained by ineffective delivery in many patients. Routine use of software algorithms and alternative catheter designs and infusion parameters may improve the efficacy of drugs delivered by CED.

Targeting DNA-PKcs and ATM with miR-101 Sensitizes Tumors to Radiation

Background Radiotherapy kills tumor-cells by inducing DNA double strand breaks (DSBs). However, the efficient repair of tumors frequently prevents successful treatment. Therefore, identifying new practical sensitizers is an essential step towards successful radiotherapy. In this study, we tested the new hypothesis: identifying the miRNAs to target DNA DSB repair genes could be a new way for sensitizing tumors to ionizing radiation. Principal Findings Here, we chose two genes: DNA-PKcs (an essential factor for non-homologous end-joining repair) and ATM (an important checkpoint regulator for promoting homologous recombination repair) as the targets to search their regulating miRNAs. By combining the database search and the bench work, we picked out miR-101. We identified that miR-101 could efficiently target DNA-PKcs and ATM via binding to the 3′- UTR of DNA-PKcs or ATM mRNA. Up-regulating miR-101 efficiently reduced the protein levels of DNA-PKcs and ATM in these tumor cells and most importantly, sensitized the tumor cells to radiation in vitro and in vivo. Conclusions These data demonstrate for the first time that miRNAs could be used to target DNA repair genes and thus sensitize tumors to radiation. These results provide a new way for improving tumor radiotherapy.

The role of chemotherapy in the management of newly diagnosed brain metastases: a systematic review and evidence-based clinical practice guideline.

Target populationThis recommendation applies to adults with newly diagnosed brain metastases; however, the recommendation below does not apply to the exquisitely chemosensitive tumors, such as germinomas metastatic to the brain.RecommendationShould patients with brain metastases receive chemotherapy in addition to whole brain radiotherapy (WBRT)?Level 1 Routine use of chemotherapy following WBRT for brain metastases has not been shown to increase survival and is not recommended. Four class I studies examined the role of carboplatin, chloroethylnitrosoureas, tegafur and temozolomide, and all resulted in no survival benefit. Two caveats are provided in order to allow the treating physician to individualize decision-making: First, the majority of the data are limited to non small cell lung (NSCLC) and breast cancer; therefore, in other tumor histologies, the possibility of clinical benefit cannot be absolutely ruled out. Second, the addition of chemotherapy to WBRT improved response rates in some, but not all trials; response rate was not the primary endpoint in most of these trials and end-point assessment was non-centralized, non-blinded, and post-hoc. Enrollment in chemotherapy-related clinical trials is encouraged.

Protease-activated receptor-1 in human brain: Localization and functional expression in astrocytes

Protease-activated receptor-1 (PAR1) is a G-protein coupled receptor that is proteolytically activated by blood-derived serine proteases. Although PAR1 is best known for its role in coagulation and hemostasis, recent findings demonstrate that PAR1 activation has actions in the central nervous system (CNS) apart from its role in the vasculature. Rodent studies have demonstrated that PAR1 is expressed throughout the brain on neurons and astrocytes. PAR1 activation in vitro and in vivo appears to influence neurodegeneration and neuroprotection in animal models of stroke and brain injury. Because of increasing evidence that PAR1 has important and diverse roles in the CNS, we explored the protein localization and function of PAR1 in human brain. PAR1 is most intensely expressed in astrocytes of white and gray matter and moderately expressed in neurons. PAR1 and GFAP co-localization demonstrates that PAR1 is expressed on the cell body and on astrocytic endfeet that invest capillaries. PAR1 activation in the U178MG human glioblastoma cell line increased PI hydrolysis and intracellular Ca(2+), indicating that PAR1 is functional in human glial-derived tumor cells. Primary cultures of human astrocytes and human glioblastoma cells respond to PAR1 activation by increasing intracellular Ca(2+). Together, these results demonstrate that PAR1 is expressed in human brain and functional in glial tumors and cultures derived from it. Because serine proteases may enter brain tissue and activate PAR1 when the blood brain barrier (BBB) breaks down, pharmacological manipulation of PAR1 signaling may provide a potential therapeutic target for neuroprotection in human neurological disorders.

A phase II study of temozolomide in patients with newly diagnosed supratentorial malignant glioma before radiation therapy

Temozolomide is a novel second-generation oral alkylating agent with demonstrated efficacy and safety in patients with recurrent glioblastoma multiforme (GBM) and anaplastic astrocytoma (AA). A multicenter phase II trial was conducted to determine the efficacy and safety of temozolomide before radiotherapy in patients with newly diagnosed GBM and AA. Fifty-seven patients (51 adult, 6 pediatric) with newly diagnosed supratentorial GBM or AA were treated with temozolomide (200 mg/m ( 2 ) per day for 5 consecutive days every 28 days) for a maximum of 4 cycles. All patients were then treated with external beam radiotherapy. Twenty-two patients (39%) achieved objective response, including 6 (11%) with complete response (CR) and 16 (28%) with partial response (PR). Additionally, 18 (32%) patients had stable disease (SD). Of 21 patients (18 adult, 3 pediatric) with AA, 2 (10%) achieved CR, 5 (24%) achieved PR, and 8 (38%) had SD. Among adult patients with AA, the median progression-free and overall survival rates were 7.6 and 23.5 months, respectively. Among 36 patients (33 adult, 3 pediatric) with GBM, 4 (11%) had CR, 11 (31%) had PR, and 10 (28%) had SD. The median progression-free and overall survival rates among adult patients with GBM were 3.9 and 13.2 months, respectively. Temozolomide was safe and well tolerated in adult and pediatric patients. Grades 3 and 4 adverse events were reported in 16 (28%) and 7 (12%) patients, respectively. Temozolomide was safe and effective in treating newly diagnosed GBM and AA before radiotherapy. This pre-irradiation treatment approach appears promising, but will require additional evaluation in comparative studies.