Carmustine wafers: localized delivery of chemotherapeutic agents in CNS malignancies

Peritumoral brain zone in glioblastoma: biological, clinical and mechanical features

Glioblastoma is a highly aggressive and invasive tumor that affects the central nervous system (CNS). With a five-year survival rate of only 6.9% and a median survival time of eight months, it has the lowest survival rate among CNS tumors. Its treatment consists of surgical resection, subsequent fractionated radiotherapy and concomitant and adjuvant chemotherapy with temozolomide. Despite the implementation of clinical interventions, recurrence is a common occurrence, with over 80% of cases arising at the edge of the resection cavity a few months after treatment. The high recurrence rate and location of glioblastoma indicate the need for a better understanding of the peritumor brain zone (PBZ). In this review, we first describe the main radiological, cellular, molecular and biomechanical tissue features of PBZ; and subsequently, we discuss its current clinical management, potential local therapeutic approaches and future prospects.

Bioinspired Hierarchical Carbon Structures as Potential Scaffolds for Wound Healing and Tissue Regeneration Applications

Engineered bio-scaffolds for wound healing provide an attractive treatment option for tissue engineering and traumatic skin injuries since they can reduce dependence on donors and promote faster repair through strategic surface engineering. Current scaffolds present limitations in handling, preparation, shelf life, and sterilization options. In this study, bio-inspired hierarchical all-carbon structures comprising carbon nanotube (CNT) carpets covalently bonded to flexible carbon fabric have been investigated as a platform for cell growth and future tissue regeneration applications. CNTs are known to provide guidance for cell growth, but loose CNTs are susceptible to intracellular uptake and are suspected to cause in vitro and in vivo cytotoxicity. This risk is suppressed in these materials due to the covalent attachment of CNTs on a larger fabric, and the synergistic benefits of nanoscale and micro-macro scale architectures, as seen in natural biological materials, can be obtained. The structural durability, biocompatibility, tunable surface architecture, and ultra-high specific surface area of these materials make them attractive candidates for wound healing. In this study, investigations of cytotoxicity, skin cell proliferation, and cell migration were performed, and results indicate promise in both biocompatibility and directed cell growth. Moreover, these scaffolds provided cytoprotection against environmental stressors such as Ultraviolet B (UVB) rays. It was seen that cell growth could also be tailored through the control of CNT carpet height and surface wettability. These results support future promise in the design of hierarchical carbon scaffolds for strategic wound healing and tissue regeneration applications.

A Local Strategy Toward Concurrent Chemoradiotherapy Based on Fibrin Gel for Postsurgical Cancer Treatment

PURPOSE

Postoperative cancer recurrence and metastasis have always been huge challenges in cancer therapy. The concurrent cisplatin (CDDP)-based chemoradiotherapy regimen is a standard therapeutic strategy in some cancer treatments after surgical resection. However, severe side effects and unsatisfactory local tumor concentrations of CDDP have hampered the application of this concurrent chemoradiotherapy. Therefore, a superior option that can enhance CDDP-based chemoradiotherapy efficacy with milder concurrent therapy-related toxicity is highly desirable.

METHODS AND MATERIALS

We developed a platform based on fibrin gel (Fgel) loaded with CDDP to be implanted into the tumor bed after surgery combined with concurrent radiation therapy for the prevention of postoperative local cancer recurrence and distant metastasis. The postoperative subcutaneous tumor mouse models established by incomplete resection of primary tumors were used to evaluate the therapeutic advantages of this chemoradiotherapy regimen for postsurgical treatment.

RESULTS

The local and sustained release of CDDP from Fgel could enhance the antitumor efficacy of radiation therapy in the residual tumor with lower systemic toxicity. The therapeutic benefits of this approach are demonstrated in breast cancer, anaplastic thyroid carcinoma, and osteosarcoma mouse models.

CONCLUSIONS

Our work offers a general platform for concurrent chemoradiotherapy to prevent postoperative cancer recurrence and metastasis.

Fabrication and Modelling of a Reservoir-Based Drug Delivery System for Customizable Release

Localized therapy approaches have emerged as an alternative drug administration route to overcome the limitations of systemic therapies, such as the crossing of the blood–brain barrier in the case of brain tumor treatment. For this, implantable drug delivery systems (DDS) have been developed and extensively researched. However, to achieve an effective localized treatment, the release kinetics of DDS needs to be controlled in a defined manner, so that the concentration at the tumor site is within the therapeutic window. Thus, a DDS, with patient-specific release kinetics, is crucial for the improvement of therapy. Here, we present a computationally supported reservoir-based DDS (rDDS) development towards patient-specific release kinetics. The rDDS consists of a reservoir surrounded by a polydimethylsiloxane (PDMS) microchannel membrane. By tailoring the rDDS, in terms of membrane porosity, geometry, and drug concentration, the release profiles can be precisely adapted, with respect to the maximum concentration, release rate, and release time. The release is investigated using a model dye for varying parameters, leading to different distinct release profiles, with a maximum release of up to 60 days. Finally, a computational simulation, considering exemplary in vivo conditions (e.g., exchange of cerebrospinal fluid), is used to study the resulting drug release profiles, demonstrating the customizability of the system. The establishment of a computationally supported workflow, for development towards a patient-specific rDDS, in combination with the transfer to suitable drugs, could significantly improve the efficacy of localized therapy approaches.

Long-term effectiveness of Gliadel ® implant for malignant glioma and prognostic factors for survival: 3-year results of a post-marketing surveillance in Japan

Background

Adjuvant treatment with Gliadel wafers may prolong overall survival (OS) for malignant glioma patients without increasing toxicity. In Japan, the long-term OS of these patients treated with Gliadel 7.7 mg implants has not been studied. We evaluated OS and prognostic factors that might affect OS in Japanese patients with malignant glioma who received the Gliadel 7.7 mg implant.

Methods

This observational, long-term, post-marketing surveillance was an extension of a previous surveillance. Data were collected through case report forms at 2 and 3 years after Gliadel implant. Up to 8 Gliadel wafers (61.6 mg of carmustine) were placed over the tumor resection site. Primary endpoints were OS and prognostic factors that may influence OS.

Results

Among the 506 patients analyzed, 62.6% had newly diagnosed disease, and 37.4% had recurrent disease; 79.1% had glioblastoma histological type and 79.6% had World Health Organization Grade IV disease. Patients received a median of 8 wafers. The median OS was 18.0 months; OS rates were 39.8% and 31.5% at 2 and 3 years, respectively. Age ≥65 years (hazard ratio [HR]: 1.456; P = 0.002), lower resection rate (HR: 1.206; P < 0.001), recurrence (HR: 2.418; P < 0.001), and concomitant radiotherapy (HR: 0.588; P < 0.001) were identified as significant prognostic factors.

Conclusions

This study confirmed the 2- and 3-year OS of Japanese malignant glioma patients with varied backgrounds after Gliadel implant. With a careful interpretation of indirect comparisons with previously reported data, the results suggest that prognosis could be improved with Gliadel implants.

Safety of Gliadel Implant for Malignant Glioma: Report of Postmarketing Surveillance in Japan

Clinical trial data of Carmustine implant (Gliadel Wafer) in Japanese patients with malignant glioma are limited; thus, we conducted a postmarketing surveillance study to evaluate the safety of Gliadel in real-world clinical practice in Japan. In this postmarketing surveillance study, all patients who received Gliadel placement for malignant glioma surgeries from its market launch (January 9, 2013) to July 10, 2013 were enrolled from 229 institutions using a central registration system. Up to eight wafers of Gliadel (containing 61.6 mg of carmustine) were used to cover the site of brain tumor resection intraoperatively according to the size and shape of the tumor resection cavity. The observation period lasted 3 months after Gliadel placement. Patients were followed up for 1 year postoperatively. Safety was assessed by the incidence of adverse events (AEs) and adverse drug reactions (ADRs). In total, 558 patients were included. Most patients (66.7%) received eight Gliadel wafers. The percentage of patients with ADRs was 35.7% (365 ADR episodes in 199 patients). Of the AEs of special interest, the most common were cerebral edema (22.2%, 124/558 patients), convulsion (9.9%, 55/558 patients), impaired healing (4.8%, 27/558 patients), and infection (3.4%, 19/558 patients). This first all-case postmarketing surveillance report of the safety of Gliadel in real-world clinical practice in Japan suggests that the risk of toxicity with Gliadel placement is relatively tolerable. The survival benefits of Gliadel placement should be evaluated and considered carefully by the clinician taking into account possible toxicities.

Local delivery to malignant brain tumors: potential biomaterial-based therapeutic/adjuvant strategies

Glioblastoma (GBM) is the most aggressive malignant brain tumor and is associated with a very poor prognosis. The standard treatment for newly diagnosed patients involves total tumor surgical resection (if possible), plus irradiation and adjuvant chemotherapy. Despite treatment, the prognosis is still poor, and the tumor often recurs within two centimeters of the original tumor. A promising approach to improving the efficacy of GBM therapeutics is to utilize biomaterials to deliver them locally at the tumor site. Local delivery to GBM offers several advantages over systemic administration, such as bypassing the blood-brain barrier and increasing the bioavailability of the therapeutic at the tumor site without causing systemic toxicity. Local delivery may also combat tumor recurrence by maintaining sufficient drug concentrations at and surrounding the original tumor area. Herein, we critically appraised the literature on local delivery systems based within the following categories: polymer-based implantable devices, polymeric injectable systems, and hydrogel drug delivery systems. We also discussed the negative effect of hypoxia on treatment strategies and how one might utilize local implantation of oxygen-generating biomaterials as an adjuvant to enhance current therapeutic strategies.

Brain-targeted, drug-loaded solid lipid nanoparticles against glioblastoma cells in culture

The aim of this study was the preparation of solid lipid nanoparticles (SLN) formed from cetyl palmitate with having targeting molecules for monocarboxylate transporter-1 (MCT-1): β-hydroxybutyric acid and anticancer agents: carmustine (BCNU) and temozolomide (TMZ) for enhanced anti-proliferation against glioblastoma multiforme (GBM). Properties including size, morphology, chemical structure, zeta potential, drug encapsulation efficacy, drug release, biocompatibility, stability were determined, and in vitro studies were done. BCNU and TMZ loaded SLNs had a hydrodynamic size of 227 nm ± 46 a zeta potential of -25 mV ± 4 with biocompatible features. The data showed rapid drug release at first and then continuous release. Nanoparticles could be stored for nine months. BCNU and TMZ loaded SLNs exhibited a remarkable increment in the antitumor activity compared to the free-drugs and induced apoptosis on U87MG cells. In addition, targeted nanoparticles were more uptaken by MCT-1 expressing brain cells. This study indicated that BCNU and TMZ loaded SLNs could act as a useful anticancer system for targeted GBM therapy.

Biocompatible copolymer formulations to treat glioblastoma multiforme

The treatment for glioblastoma multiforme (GBM) has not changed for more than 20 years while the prognosis for the patients is still poor and most of them survive less than 1 year after diagnosis. The standard of care for GBM is comprised of surgical resection followed by radiotherapy and oral chemotherapy with temozolomide. The placement of carmustine wafers in the brain after tumour removal is added in cases of recurrent glioma. Significant research is underway to improve the GBM therapy outcome and patient quality of life. Biomaterials are in the front line of the research focus for new treatment options. Specially, biocompatible polymers have been proposed in hydrogel-based formulations aiming at injectable and localized therapies. These formulations can comprise many different pharmacological agents such as chemotherapeutic drugs, nanoparticles, cells, nucleic acids, and diagnostic agents. In this manuscript, we review the most recent formulations developed and tested both in vitro and in vivo using different types of hydrogels. Firstly, we describe three common types of thermo-responsive polymers addressing the advantages and drawbacks of their formulations. Then, we focus on formulations specifically developed for GBM treatment.

Multi-walled carbon nanotube carpets as scaffolds for U87MG glioblastoma multiforme cell growth

Carbon Nanotubes (CNTs) are known for effective adhesion, growth, and differentiation of bone, muscle, and cardiac cells. CNTs can provide excellent mechanical and electrical properties for cell scaffolding; however, loose CNTs can cause in-vivo toxicity. To suppress this risk, our team has developed biomimetic scaffolds with multiscale hierarchy where carpet-like CNT arrays are covalently bonded to larger biocompatible substrates. In this study, we investigated the interaction between glioblastoma multiforme (GBM) cells (U87MG) and our unique hierarchical CNT-coated scaffolds upon brain tumor cell proliferation. U87MG cells grown on un-modified carbon scaffolds grew in a bi-phasic fashion. Initially, the scaffolds prevented GBM cell growth; however, prolonged growth on such scaffolds significantly increased GBM cell proliferation. We further defined the importance of the hydrophobicity/hydrophilicity of the CNT-coated scaffolds in this cellular response by utilizing sodium-hypochlorite based bleach treatment prior to cellular exposure. This surface modification increased the hydrophilicity of the CNT-coated scaffolds and ameliorated the biphasic response of U87MG cells allowing for a normal growth curve. Findings highlight the importance of surface modification and wettability of the CNT-coated scaffolds for cell growth applications. The focus for this study was to determine whether scaffold surface features could modulate tumor-scaffold interactions, and thus to improve our understanding of and optimize successful development of future scaffold-based chemotherapy applications. Overall, it appears that the wettability of carbon scaffolds coated with CNTs is an important regulator of U87MG cellular growth. These findings will be important to consider when developing a potential chemotherapy-attached implant to be used post-surgical resection for GBM patient treatment.

Codelivery of paclitaxel and temozolomide through a photopolymerizable hydrogel prevents glioblastoma recurrence after surgical resection

A photopolymerizable hydrogel-based local drug delivery system was developed for the postsurgical treatment of glioblastoma (GBM). We aimed for a local drug combination therapy with paclitaxel (PTX) and temozolomide (TMZ) within a hydrogel to synergistically inhibit tumor growth. The in vitro cytotoxicity of TMZ was assessed in U87MG cells. We demonstrated the synergistic effect of PTX and TMZ on U87MG cells by clonogenic assay. Treatment with TMZ did not induce O6-methylguanine-DNA methyltransferase related drug resistance in tumor-bearing mice. PTX had sustained release for at least 1 month in vivo in healthy mice brains. The drug combination was tolerable and suppressed tumor growth more efficiently than the single drugs in the U87MG orthotopic tumor model. The PTX and TMZ codelivery hydrogel showed superior antitumor effects and can be considered a promising approach for the postsurgical treatment of GBM.

A drug combination targeting hypoxia induced chemoresistance and stemness in glioma cells

Hypoxia is a characteristic of solid tumors especially Glioblastoma and is critical to chemoresistance. Cancer stem cells present in hypoxic niches are known to be a major cause of the progression, metastasis and relapse. We tried to identify synergistic combinations of drugs effective in both hypoxia and normoxia in tumor cells as well as in cancer stem cells. Since COX-2 is over-expressed in subset of glioblastoma and is also induced in hypoxia, we studied combinations of a prototype Cyclooxygenase (COX-2) inhibitor, NS-398 with various drugs (BCNU, Temozolomide, 2-Deoxy-D-glucose and Cisplatin) for their ability to abrogate chemoresistance under both severe hypoxia (0.2% O₂) and normoxia (20% O₂) in glioma cells. The only effective combination was of NS-398 and BCNU which showed a synergistic effect in both hypoxia and normoxia. This synergism was evident at sub-lethal doses for either of the single agent. The effectiveness of the combination resulted from increased pro- apoptotic and decreased anti-apoptotic molecules and increased caspase activity. PGE₂ levels, a manifestation of COX-2 activity were increased during hypoxia, but were reduced by the combination during both hypoxia and normoxia. The combination reduced the levels of epithelial-mesenchymal transition (EMT) markers. It also resulted in a greater reduction of cell migration. While single drugs could reduce the number of gliomaspheres, the combination successfully abrogated their formation. The combination also resulted in a greater reduction of the cancer stem cell marker CD133. This combination could be a prototype of possible therapy in a tumor with a high degree of hypoxia like glioma.

Breaching barriers in glioblastoma. Part I: Molecular pathways and novel treatment approaches

Glioblastoma multiforme (GBM) is the most common primary brain tumour, and the most aggressive in nature. The prognosis for patients with GBM remains poor, with a median survival time of only 1-2 years. The treatment failure relies on the development of resistance by tumour cells and the difficulty of ensuring that drugs effectively cross the dual blood brain barrier/blood brain tumour barrier. The advanced molecular and genetic knowledge has allowed to identify the mechanisms responsible for temozolomide resistance, which represents the standard of care in GBM, along with surgical resection and radiotherapy. Such resistance has motivated the researchers to investigate new avenues for GBM treatment intended to improve patient survival. In this review, we provide an overview of major obstacles to effective treatment of GBM, encompassing biological barriers, cancer stem cells, DNA repair mechanisms, deregulated signalling pathways and autophagy. New insights and potential therapy approaches for GBM are also discussed, emphasizing localized chemotherapy delivered directly to the brain, immunotherapy, gene therapy and nanoparticle-mediated brain drug delivery.

Nanotherapeutic systems for local treatment of brain tumors

Malignant brain tumor, including the most common type glioblastoma, are histologically heterogeneous and invasive tumors known as the most devastating neoplasms with high morbidity and mortality. Despite multimodal treatment including surgery, radiotherapy, chemotherapy, and immunotherapy, the disease inevitably recurs and is fatal. This lack of curative options has motivated researchers to explore new treatment strategies and to develop new drug delivery systems (DDSs); however, the unique anatomical, physiological, and pathological features of brain tumors greatly limit the effectiveness of conventional chemotherapy. In this context, we review the recent progress in the development of nanoparticle-based DDSs aiming to address the key challenges in transporting sufficient amount of therapeutic agents into the brain tumor areas while minimizing the potential side effects. We first provide an overview of the standard treatments currently used in the clinic for the management of brain cancers, discussing the effectiveness and limitations of each therapy. We then provide an in-depth review of nanotherapeutic systems that are intended to bypass the blood-brain barrier, overcome multidrug resistance, infiltrate larger tumorous tissue areas, and/or release therapeutic agents in a controlled manner. WIREs Nanomed Nanobiotechnol 2018, 10:e1479. doi: 10.1002/wnan.1479 This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

The ability of hyaluronan fragments to reverse the resistance of C6 rat glioma cell line to temozolomide and carmustine

Aim of the study

Hyaluronan (HA) is an extracellular matrix (ECM) polymer that may contribute to the emergence of anti-cancer drug resistance. Attempts to reverse drug resistance using small hyaluronan oligomers (oHA) are being made. The initial reports suggest that the oHA fraction may effectively reverse anti-cancer drug resistance in glioma models. However, the reversal effects of oHA of defined molecular length on glioma cells have not been investigated yet. In this study, we examined HA fragments containing 2 disaccharide units (oHA-2), 5 disaccharide units (oHA-5), and 68 kDa hyaluronan polymer (HA-68k) as agents possibly reversing the resistance of a C6 rat glioma cell line to temozolomide (TMZ) and carmustine (BCNU).

Material and methods

A 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) viability assay was used to assess the cytotoxicity of TMZ and BCNU in the presence or absence of the hyaluronan fragments. By comparing viability of the cells, the reversal effects of HA fragments on TMZ and BCNU resistance in C6 glioma cells were assessed.

Results

We found statistically significant decreases in the viability of cells in the presence of TMZ+oHA-5 as compared to TMZ alone (51.2 ±4.5 vs. 74.2 ±5.8, p = 0.0031), BCNU+o-HA5 as compared to BCNU alone (49.3 ±4.4 vs. 65.6 ±5.7, p = 0.0119), and BCNU+HA-68k as compared to BCNU alone (55.2 ±2.3 vs. 65.6 ±5.7, p = 0.0496).

Conclusions

Conclusions: Hyaluronan oligomers of 5 disaccharide units (oHA-5) significantly reversed the resistance of C6 cells to TMZ and BCNU. The results are only preliminary and a more thorough follow-up investigation is required to assess their actual role.

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.

Tumor cohesion and glioblastoma cell dispersal

Patients with glioblastoma typically present when tumors are at an advanced stage. Surgical resection, radiotherapy and adjuvant chemotherapy are currently the standard of care for glioblastoma. However, due to the infiltrative and dispersive nature of the tumor, recurrence rate remains high and typically results in very poor prognosis. Efforts to treat the primary tumor are, therefore, palliative rather than curative. From a practical perspective, controlling growth and dispersal of the recurrence may have a greater impact on disease-free survival. In order for cells to disperse, they must first detach from the mass. Preventing detachment may keep tumors that recur more localized and perhaps more amenable to therapy. Here we introduce a new perspective in which a quantifiable mechanical property, namely tissue surface tension, can provide novel information on tumor behavior. The overall theme of the discussion will attempt to integrate how adhesion molecules can alter a tumor's mechanical properties and how, in turn, these properties can be modified to prevent tumor cell detachment and dispersal.

Carmustine-induced phosphatidylserine translocation in the erythrocyte membrane

The nitrosourea alkylating agent, carmustine, is used as chemotherapeutic drug in several malignancies. The substance triggers tumor cell apoptosis. Side effects of carmustine include myelotoxicity with anemia. At least in theory, anemia could partly be due to stimulation of eryptosis, the suicidal death of erythrocytes, characterized by cell shrinkage and breakdown of phosphatidylserine asymmetry of the cell membrane with phosphatidylserine exposure at the erythrocyte surface. Stimulators of eryptosis include increase of cytosolic Ca²⁺ activity ([Ca²⁺]i). The present study tested whether carmustine triggers eryptosis. To this end [Ca²⁺]i was estimated from Fluo3 fluorescence, cell volume from forward scatter, phosphatidylserine exposure from annexin V binding, and hemolysis from hemoglobin release. As a result a 48 h exposure to carmustine (≥25 µM) significantly increased [Ca²⁺]i, decreased forward scatter and increased annexin V binding. The effect on annexin V binding was significantly blunted in the absence of extracellular Ca²⁺. In conclusion, carmustine stimulates eryptosis at least partially by increasing cytosolic Ca²⁺ activity.

Polifeprosan 20, 3.85% carmustine slow-release wafer in malignant glioma: evidence for role in era of standard adjuvant temozolomide

The Polifeprosan 20 with carmustine (BCNU, bis-chloroethylnitrosourea, Gliadel^®) polymer implant wafer is a biodegradable compound containing 3.85% carmustine which slowly degrades to release carmustine and protects it from exposure to water with resultant hydrolysis until the time of release. The carmustine implant wafer was demonstrated to improve survival in blinded placebo-controlled trials in selected patients with newly diagnosed or recurrent malignant glioma, with little increased risk of adverse events. Based on these trials and other supporting data, US and European regulatory authorities granted approval for its use in recurrent and newly diagnosed malignant glioma, and it remains the only approved local treatment. The preclinical and clinical data suggest that it is optimally utilized primarily in the proportion of patients who may have total or near total removal of gross tumor. The aim of this work was to review the evidence for the use of carmustine implants in the management of malignant astrocytoma (World Health Organization grades III and IV), including newly diagnosed and recurrent disease, especially in the setting of a standard of care that has changed since the randomized trials were completed. Therapy has evolved such that patients now generally receive temozolomide chemotherapy during and after radiotherapy treatment. For patients undergoing repeat resection for malignant glioma, a randomized, blinded, placebo-controlled trial demonstrated a median survival for 110 patients who received carmustine polymers of 31 weeks compared with 23 weeks for 122 patients who only received placebo polymers. The benefit achieved statistical significance only on analysis adjusting for prognostic factors rather than for the randomized groups as a whole (hazard ratio = 0.67, P = 0.006). A blinded, placebo-controlled trial has also been performed for carmustine implant placement in newly diagnosed patients prior to standard radiotherapy. Median survival was improved from 11.6 to 13.9 months (P = 0.03), with a 29% reduction in the risk of death. When patients with glioblastoma multiforme alone were analyzed, the median survival improved from 11.4 to 13.5 months, but this improvement was not statistically significant. When a Cox’s proportional hazard model was utilized to account for other potential prognostic factors, there was a significant 31% reduction in the risk of death (P = 0.04) in this subgroup. Data from other small reports support these results and confirm that the incidence of adverse events does not appear to be increased meaningfully. Given the poor prognosis without possibility of cure, these benefits from a treatment with a favorable safety profile were considered meaningful. There is randomized evidence to support the use of carmustine wafers placed during resection of recurrent disease. Therefore, although there is limited specific evidence, this treatment is likely to be efficacious in an environment when nearly all patients receive temozolomide as part of initial management. Given that half of the patients in the randomized trial assessing the value of carmustine implants in recurrent disease had received prior chemotherapy, it is likely that this remains a valuable treatment at the time of repeat resection, even after temozolomide. There are data from multiple reports to support safety. Although there is randomized evidence to support the use of this therapy in newly diagnosed patients who will receive radiotherapy alone, it is now standard to administer both adjuvant temozolomide and radiotherapy. There are survival outcome reports for small cohorts of patients receiving temozolomide with radiotherapy, but this information is not sufficient to support firm recommendations. Based on the rationale and evidence of safety, this approach appears to be a reasonable option as more information is acquired. Available data support the safety of using carmustine wafers in this circumstance, although special attention to surgical guidelines for implanting the wafers is warranted.

Thioredoxin reductase is inhibited by the carbamoylating activity of the anticancer sulfonylhydrazine drug laromustine

The thioredoxin system facilitates proliferative processes in cells and is upregulated in many cancers. The activities of both thioredoxin (Trx) and its reductase (TrxR) are mediated by oxidation/reduction reactions among cysteine residues. A common target in preclinical anticancer research, TrxR is reported here to be significantly inhibited by the anticancer agent laromustine. This agent, which has been in clinical trials for acute myelogenous leukemia and glioblastoma multiforme, is understood to be cytotoxic principally via interstrand DNA crosslinking that originates from a 2-chloroethylating species generated upon activation in situ. The spontaneous decomposition of laromustine also yields methyl isocyanate, which readily carbamoylates thiols and primary amines. Purified rat liver TrxR was inhibited by laromustine with a clinically relevant IC(50) value of 4.65 μM. A derivative of laromustine that lacks carbamoylating activity did not appreciably inhibit TrxR while another derivative, lacking only the 2-chloroethylating activity, retained its inhibitory potency. Furthermore, in assays measuring TrxR activity in murine cell lysates, a similar pattern of inhibition among these compounds was observed. These data contrast with previous studies demonstrating that glutathione reductase, another enzyme that relies on cysteine-mediated redox chemistry, was not inhibited by methylcarbamoylating agents when measured in cell lysates. Mass spectrometry of laromustine-treated enzyme revealed significant carbamoylation of TrxR, albeit not on known catalytically active residues. However, there was no evidence of 2-chloroethylation anywhere on the protein. The inhibition of TrxR is likely to contribute to the cytotoxic, anticancer mechanism of action for laromustine.

Nanoengineered drug-releasing Ti wires as an alternative for local delivery of chemotherapeutics in the brain

The blood–brain barrier (BBB) blocks the passage of active molecules from the blood which makes drug delivery to the brain a challenging problem. Oral drug delivery using chemically modified drugs to enhance their transport properties or remove the blocking of drug transport across the BBB is explored as a common approach to address these problems, but with limited success. Local delivery of drugs directly to the brain interstitium using implants such as polymeric wafers, gels, and catheters has been recognized as a promising alternative particularly for the treatment of brain cancer (glioma) and neurodegenerative disorders. The aim of this study was to introduce a new solution by engineering a drug-releasing implant for local drug delivery in the brain, based on titanium (Ti) wires with titania nanotube (TNT) arrays on their surfaces. Drug loading and drug release characteristics of this system were explored using two drugs commonly used in oral brain therapy: dopamine (DOPA), a neurotransmitter agent; and doxorubicin (DOXO), an anticancer drug. Results showed that TNT/Ti wires could provide a considerable amount of drugs (>170 μg to 1000 μg) with desirable release kinetics and controllable release time (1 to several weeks) and proved their feasibility for use as drug-releasing implants for local drug delivery in the brain.

Targeted polymeric therapeutic nanoparticles: design, development and clinical translation

Polymeric materials have been used in a range of pharmaceutical and biotechnology products for more than 40 years. These materials have evolved from their earlier use as biodegradable products such as resorbable sutures, orthopaedic implants, macroscale and microscale drug delivery systems such as microparticles and wafers used as controlled drug release depots, to multifunctional nanoparticles (NPs) capable of targeting, and controlled release of therapeutic and diagnostic agents. These newer generations of targeted and controlled release polymeric NPs are now engineered to navigate the complex in vivo environment, and incorporate functionalities for achieving target specificity, control of drug concentration and exposure kinetics at the tissue, cell, and subcellular levels. Indeed this optimization of drug pharmacology as aided by careful design of multifunctional NPs can lead to improved drug safety and efficacy, and may be complimentary to drug enhancements that are traditionally achieved by medicinal chemistry. In this regard, polymeric NPs have the potential to result in a highly differentiated new class of therapeutics, distinct from the original active drugs used in their composition, and distinct from first generation NPs that largely facilitated drug formulation. A greater flexibility in the design of drug molecules themselves may also be facilitated following their incorporation into NPs, as drug properties (solubility, metabolism, plasma binding, biodistribution, target tissue accumulation) will no longer be constrained to the same extent by drug chemical composition, but also become in-part the function of the physicochemical properties of the NP. The combination of optimally designed drugs with optimally engineered polymeric NPs opens up the possibility of improved clinical outcomes that may not be achievable with the administration of drugs in their conventional form. In this critical review, we aim to provide insights into the design and development of targeted polymeric NPs and to highlight the challenges associated with the engineering of this novel class of therapeutics, including considerations of NP design optimization, development and biophysicochemical properties. Additionally, we highlight some recent examples from the literature, which demonstrate current trends and novel concepts in both the design and utility of targeted polymeric NPs (444 references).

Temporal changes in magnetic resonance imaging characteristics of Gliadel wafers and of the adjacent brain parenchyma

Carmustine is used in the treatment of glioblastomas as locally applied chemotherapy in the form of biodegradable wafers, which are lined on the walls of the resection cavity at the end of the resection, to increase local concentrations and decrease systemic toxicity. A total of 44 patients with glioblastoma with gross macroscopic tumor removal were included. MRIs were performed at various times postoperatively (within 24 hours, 1 week, 1 month, 2 months, 3 months, 6 months, 9 months, and 1 year). MR protocols included a T2-, diffusion-weighted, and T1-weighted sequences with and without intravenous administration of gadolinium. On T1, the wafers change from their initial hypointense to an isointense appearance after a period during which they appear to be hypointense, with a hyperintense rim most prominent less than 1 month postoperatively. On T2 they change from a hypointense to an isointense appearance. Restricted diffusivity reshaping the silhouette of the wafer's surface at the rim of the resection cavity can be found as early as day 1 postoperatively; however, 1 month after implantation, they all show areas of restricted diffusion, which may remain up to 1 year. Contrast enhancement at the rim of the resection cavity can already be found at day 1 postoperatively, with a peak shortly after 1 month after surgery. These changes can easily be mistaken for an abscess and hamper the early differentiation between residual tumor tissue and normal postoperative changes. However, early changes in either appearance do not predict overall survival or the progression free interval.

Prognostic factors and survival in a prospective cohort of patients with high-grade glioma treated with carmustine wafers or temozolomide on an intention-to-treat basis

BACKGROUND

Patients with high-grade glioma can be treated with carmustine wafers or following the Stupp protocol. As far as we are aware, no scientific evidence has been published comparing the two treatments. The primary objective of this study was to analyse the survival of groups of patients with each of these treatment modalities. The secondary objective was to assess the influence of the usual prognostic factors on the patients in our hospital.

METHODS

A prospective cohort of 110 patients with single, supratentorial high-grade glioma treated by craniotomy and tumour resection was retrospectively studied. Half of the patients had carmustine wafers placed during this operation while the others (55) did not, the latter group receiving first-line systemic chemotherapy on an intention-to-treat basis.

FINDINGS

Patients treated with carmustine wafers had a median survival of 13.414 months compared with 11.047 in the group without implants (p = 0.856). For the overall cohort of patients, the following factors were found to influence survival: age (p < 0.0001), postoperative KPS score (p = 0.001), histological grade (p = 0.004), RPA class (p = 0.001), extent of resection (p = 0.002) and salvage surgery (p = 0.028).

CONCLUSIONS

In this prospective cohort of patients, analysed on the basis of intention-to-treat at the time of the first surgery, no statistically significant differences in survival were found between the two treatment modalities (carmustine wafers vs. first-line systemic chemotherapy). On the other hand, age, preoperative KPS, histological grade, and RPA class were confirmed to be prognostic factors in this cohort. Finally, the extent of resection was also found to influence survival.

The three-layer concentric model of glioblastoma: cancer stem cells, microenvironmental regulation, and therapeutic implications

Tumors arising in the central nervous system are thought to originate from a sub-population of cells named cancer stem cells (CSCs) or tumor initiating cells (TICs) that possess an immature phenotype, combined with self-renewal and chemotherapy resistance capacity. Moreover, in the last years, these cells have been identified in particular brain tumor niches fundamental for supporting their characteristics. In this paper, we report studies from many authors demonstrating that hypoxia or the so called “hypoxic niche” plays a crucial role in controlling CSC molecular and phenotypic profile. We recently investigated the relationship existing between Glioblastoma (GBM) stem cells and their niche, defining the theory of three-concentric layers model for GBM mass. According to this model, GBM stem cells reside preferentially within the hypoxic core of the tumour mass, while more differentiated cells are mainly localized along the peripheral and vascularized part of the tumour. This GBM model provides explanation of the effects mediated by the tumour microenvironment on the phenotypic and molecular regulation of GBM stem cells, describing their spatial distribution in the tumor bulk. Moreover, we discuss the possible clinical implications of the creation of this model for future GBM patient management and novel therapeutic strategies development.

Therapeutic options for recurrent malignant glioma

BACKGROUND AND PURPOSE

Despite the given advances in neuro-oncology most patients with high grade malignant glioma ultimately fail locally or locoregionally. In parallel with improvements of initial treatment options, several salvage strategies have been elucidated and already entered clinical practice. Aim of this article is to review the current status of salvage strategies in recurrent high grade glioma.

MATERIAL AND METHODS

Using the following MESH headings and combinations of these terms the pubmed database was searched: "Glioma", "Recurrence", "Neoplasm Recurrence, Local", "Radiosurgery", "Brachytherapy", "Neurosurgical Procedures" and "Drug Therapy". For citation crosscheck the ISI web of science database was used employing the same search terms. In parallel, the abstracts of ASCO 2008-2009 were analyzed accordingly.

RESULTS

Currently the following options for salvage entered clinical practice: re-resection, re-irradiation (stereotactic radiosurgery, (hypo-)fractionated (stereotactic) radiotherapy, interstitial brachytherapy) or single/poly-chemotherapy schedules including new dose-intensified or alternative treatment protocols employing targeted drugs. Re-operation is associated with high morbidity and mortality, however, is an option in a highly selected patient cohort. Since toxicity has been overestimated, re-irradiation is an increasingly used option with precise fractionated radiotherapy being the most optimal technique. On average, time to secondary progression is in the range of several months. Conventional chemotherapy regimens also improve time to secondary progression; however the efficacy is only modest and treatment-related toxicities like myelo-suppression occur very frequently. Molecular targeted agents/kinases are undergoing clinical testing; however no final recommendations can be made.

CONCLUSIONS

Currently, several re-treatment options with only modest efficacy exist. The relative value of each approach compared to other options is unknown as well as it remains open which sequence of modalities should be chosen.

Novel magnetic/ultrasound focusing system enhances nanoparticle drug delivery for glioma treatment

Malignant glioma is a common and severe primary brain tumor with a high recurrence rate and an extremely high mortality rate within 2 years of diagnosis, even when surgical, radiological, and chemotherapeutic interventions are applied. Intravenously administered drugs have limited use because of their adverse systemic effects and poor blood-brain barrier penetration. Here, we combine 2 methods to increase drug delivery to brain tumors. Focused ultrasound transiently permeabilizes the blood-brain barrier, increasing passive diffusion. Subsequent application of an external magnetic field then actively enhances localization of a chemotherapeutic agent immobilized on a novel magnetic nanoparticle. Combining these techniques significantly improved the delivery of 1,3-bis(2-chloroethyl)-1-nitrosourea to rodent gliomas. Furthermore, the physicochemical properties of the nanoparticles allowed their delivery to be monitored by magnetic resonance imaging (MRI). The resulting suppression of tumor progression without damaging the normal regions of the brain was verified by MRI and histological examination. This noninvasive, reversible technique promises to provide a more effective and tolerable means of tumor treatment, with lower therapeutic doses and concurrent clinical monitoring.

Doxorubicin and irinotecan drug-eluting beads for treatment of glioma: a pilot study in a rat model

Despite some progress in therapy, the prognosis of patients with malignant gliomas remains poor. Local delivery of cytostatics to the tumour has been proven to be an efficacious therapeutic approach but which nevertheless needs further improvements. Drug Eluting Beads (DEB), have been developed as drug delivery embolisation systems for use in trans-arterial chemoembolisation. We tested in a rat model of malignant glioma, whether DEB, loaded with doxorubicin or irinotecan, may be used for local treatment of brain tumours. Unloaded and drug loaded DEB were implanted into the brains of healthy and tumour bearing BD IX rats followed by histological investigations and survival assessment. Intracerebral implantation of unloaded DEB caused no significant local tissue damage, whilst both doxorubicin and irinotecan DEB improved survival time significantly. However, a significant local toxicity was found after the implantation of doxorubicin DEB but not with irinotecan DEB. We concluded that irinotecan appears to be superior in terms of the risk-benefit ratio and that DEB may be used for local treatment of brain tumours.

Effect of O6-chloroethylguanine DNA lesions on the kinetics and mechanism of micronucleus induction in vivo

The aim of this work was to determine the kinetics of micronucleus production because of an increase in O(6)-chloroethyl guanine (O6-ChlEt-G) DNA lesions in murine bone marrow cells in vivo. We increased the frequency of O6-ChlEt-G lesions by pretreatment with an inhibitor of O(6)-methylguanine-DNA methyltransferase (MGMT), O(6)-benzylguanine (O6BG), and subsequent treatment with bis-chloroethylnitrosourea (BCNU). The kinetics of micronucleated-polychromatic erythrocyte (MN-PCE) induction was established by scoring the frequency of MN-PCEs per 2000 PCEs in peripheral blood at 8-hr intervals from immediately prior to treatment to 72-hr post-treatment. We examined groups of five mice treated with (i) dimethylsulfoxide (DMSO), (ii) O6BG in DMSO, (iii) BCNU, or (iv) O6BG in DMSO plus BCNU. The data indicate that O6BG pretreatment causes: (i) ían increase in MN-PCEs induced by BCNU, (ii) a delay in the time of maximal MN-PCE induction produced by the different BCNU doses, and (iii) an increase in cytotoxicity. These data confirm that O6-ChlEt-G is a lesion involved in DNA break induction and in the subsequent production of micronuclei, and also that these lesions seem to be stoichiometrically reduced by MGMT. These data also show that induction of MN-PCEs by BCNU is delayed by pretreatment with O6BG for more than 6 hr, perhaps due to the time required for repair of crosslinks derived from O6-ChlEt-G and/or for DNA duplication, which is required for adduct transformation into crosslinks.

Effective transvascular delivery of nanoparticles across the blood-brain tumor barrier into malignant glioma cells

BACKGROUND

Effective transvascular delivery of nanoparticle-based chemotherapeutics across the blood-brain tumor barrier of malignant gliomas remains a challenge. This is due to our limited understanding of nanoparticle properties in relation to the physiologic size of pores within the blood-brain tumor barrier. Polyamidoamine dendrimers are particularly small multigenerational nanoparticles with uniform sizes within each generation. Dendrimer sizes increase by only 1 to 2 nm with each successive generation. Using functionalized polyamidoamine dendrimer generations 1 through 8, we investigated how nanoparticle size influences particle accumulation within malignant glioma cells.

METHODS

Magnetic resonance and fluorescence imaging probes were conjugated to the dendrimer terminal amines. Functionalized dendrimers were administered intravenously to rodents with orthotopically grown malignant gliomas. Transvascular transport and accumulation of the nanoparticles in brain tumor tissue was measured in vivo with dynamic contrast-enhanced magnetic resonance imaging. Localization of the nanoparticles within glioma cells was confirmed ex vivo with fluorescence imaging.

RESULTS

We found that the intravenously administered functionalized dendrimers less than approximately 11.7 to 11.9 nm in diameter were able to traverse pores of the blood-brain tumor barrier of RG-2 malignant gliomas, while larger ones could not. Of the permeable functionalized dendrimer generations, those that possessed long blood half-lives could accumulate within glioma cells.

CONCLUSION

The therapeutically relevant upper limit of blood-brain tumor barrier pore size is approximately 11.7 to 11.9 nm. Therefore, effective transvascular drug delivery into malignant glioma cells can be accomplished by using nanoparticles that are smaller than 11.7 to 11.9 nm in diameter and possess long blood half-lives.

Present trend in the primary treatment of aggressive malignant glioma: glioblastoma multiforme

The standard treatment for glioblastoma multiforme is surgery, radiation, and chemotherapy. Yet this aggressive therapy has only a modest effect on survival with most patients surviving less than 1 year after diagnosis. This poor prognosis has lead scientists to seek alternative molecular approaches for the treatment of glioblastoma multiforme. Among these, gene therapy, vaccine therapy, and immunotherapy are all approaches that are currently being investigated. While these molecular approaches may not herald an immediate change in the prognosis of these aggressive tumors, combining them with existing approaches may bring some progress in the standard of care. This paper reviews current treatments and several newer therapies in preclinical and early clinical studies.