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Purpose: High-grade glioma (HGG) treatment is limited by the inability of otherwise potentially efficacious drugs to penetrate the blood–brain barrier. We evaluate the unique intracavity delivery mode and translational potential of a blend of poly(DL-lactic acid-co-glycolic acid; PLGA) and poly(ethylene glycol; PEG) paste combining temozolomide and etoposide to treat surgically resected HGG. Experimental Design: To prolong stability of temozolomide prodrug, combined in vitro drug release was quantitatively assessed from low pH–based PLGA/PEG using advanced analytic methods. In vitro cytotoxicity was measured against a panel of HGG cell lines and patient-derived cultures using metabolic assays. In vivo safety and efficacy was evaluated using orthotopic 9L gliosarcoma allografts, previously utilized preclinically to develop Gliadel. Results: Combined etoposide and temozolomide in vitro release (22 and 7 days, respectively) was achieved from a lactic acid–based PLGA/PEG paste, used to enhance stability of temozolomide prodrug. HGG cells from central-enhanced regions were more sensitive to each compound relative to primary lines derived from the HGG-invasive margin. Both drugs retained cytotoxic capability upon release from PLGA/PEG. In vivo studies revealed a significant overall survival benefit in postsurgery 9L orthotopic gliosarcomas, treated with intracavity delivered PLGA/PEG/temozolomide/etoposide and enhanced with adjuvant radiotherapy. Long-term survivorship was observed in over half the animals with histologic confirmation of disease-free brain. Conclusions: The significant survival benefit of intracavity chemotherapy demonstrates clinical applicability of PLGA/PEG paste-mediated delivery of temozolomide and etoposide adjuvant to radiotherapy. PLGA/PEG paste offers a future platform for combination delivery of molecular targeted compounds.

INTRODUCTION: The blood brain barrier is a critical limiting step to achieving therapeutic CNS drug concentrations. We have developed a poly(lactic-co-glycolic acid)/poly(ethylene glycol) (PLGA/PEG)-based Platform Technology to interstitially deliver multiple chemotherapy agents from a single thermo-setting paste, potentially filling the 3-week therapy gap that currently exists between surgery and commencement of radiotherapy in the treatment of high grade gliomas. Here we evaluate mouldable PLGA/PEG paste for combined temozolomide (TMZ) and etoposide (ETOP) delivery in an orthotopic high grade glioma model. METHODS: Drug release and preserved stability of the active TMZ molecule (AIC) was evaluated by fluoroscopic and LC-mass spectrometer based methods. In vitro cytotoxicity of released TMZ/ETOP was evaluated against high grade glioma cell lines and patient-derived primary cultures using metabolic assays. In vivo efficacy and overall survival were evaluated in the syngenic orthotopic 9L glioma rat model of intra cavity chemotherapy. RESULTS: TMZ and ETOP were released from PLGA/PEG alone or in combination over 2 weeks in vitro. Cytotoxicity of released drugs in vitro is comparable to directly applied agents, demonstrating the retained molecular integrity of TMZ/ETOP upon loading and releasing from PLGA/PEG. Both high (20% w/w TMZ / 50% w/w ETOP) and low (10% w/w TMZ / 25% w/w ETOP) doses were well tolerated in vivo, with no observable weight loss nor neurological deficits. Significant survival benefits from PLGA/PEG/TMZ/ETOP therapy were observed compared to surgery alone (49 vs. 14 days; p < 0.001), surgery with blank paste (49 vs. 14 days; p < 0.001) or surgery with daily oral TMZ (49 vs. 33 days; p < 0.004). CONCLUSIONS: This study demonstrates that interstitial delivery of TMZ/ETOP achieves significant glioma survival benefits. As such, PLGA/PEG paste applied to the post-surgical resection cavity offers a realistic opportunity for localised control of residual disease in pediatric and adult high grade gliomas.

Objectives/Hypothesis: To develop a porous, biodegradable scaffold for mastoid air-cell regeneration. Study Design: In vitro development of a temperature-sensitive poly(DL-lactic acid-co-glycolic acid)/poly(ethylene glycol) (PLGA/PEG) scaffold tailored for this application. Methods: Human mastoid bone microstructure and porosity were investigated using micro-computed tomography. PLGA/PEG-alginate scaffolds were developed, and scaffold porosity was assessed. Human bone marrow mesenchymal stem cells (hBM-MSCs) were cultured on the scaffolds in vitro. Scaffolds were loaded with ciprofloxacin, and release of ciprofloxacin over time in vitro was assessed. Results: Porosity of human mastoid bone was measured at 83% with an average pore size of 1.3 mm. PLGA/PEG-alginate scaffold porosity ranged from 43% to 78% depending on the alginate bead content. The hBM-MSCs proliferate on the scaffolds in vitro, and release of ciprofloxacin from the scaffolds was demonstrated over 7 to 10 weeks. Conclusions: The PLGA/PEG-alginate scaffolds developed in this study demonstrate similar structural features to human mastoid bone, support cell growth, and display sustained antibiotic release. These scaffolds may be of potential clinical use in mastoid air-cell regeneration. Further in vivo studies to assess the suitability of PLGA/PEG-alginate scaffolds for this application are required. Key Words: Scaffold, poly(DL-lactic acid-co-glycolic acid), alginate, mastoid, ciprofloxacin. Level of Evidence: N/A.

Sustained and controlled delivery of growth factors, such as bone morphogenetic protein 2 (BMP-2), from polymer scaffolds has excellent potential for enhancing bone regeneration. The present study investigated the use of novel sintered polymer scaffolds prepared using temperature-sensitive PLGA/PEG particles. Growth factors can be incorporated into these scaffolds by mixing the reconstituted growth factor with the particles prior to sintering. The ability of the PLGA/PEG scaffolds to deliver BMP-2 in a controlled and sustained manner was assessed and the osteogenic potential of these scaffolds was determined in a mouse calvarial defect model. BMP-2 was released from the scaffolds in vitro over 3 weeks. On average, ca. 70% of the BMP-2 loaded into the scaffolds was released by the end of this time period. The released BMP-2 was shown to be active and to induce osteogenesis when used in a cell culture assay. A substantial increase in new bone volume of 55% was observed in a mouse calvarial defect model for BMP-2-loaded PLGA/PEG scaffolds compared to empty defect controls. An increase in new bone volume of 31% was observed for PLGA/PEG scaffolds without BMP-2, compared to empty defect controls. These results demonstrate the potential of novel PLGA/PEG scaffolds for sustained BMP-2 delivery for bone-regeneration applications. Copyright © 2012 John Wiley & Sons, Ltd.

INTRODUCTION: Surgically delivering chemotherapy to a resection cavity offers hope in targeting residual glioblastoma cells responsible for tumour recurrence. We conducted a systematic review of 311 agents combining scientific literature, clinical trial databases and chemical structure directories, to identify candidates suitable to repurpose for localised glioblastoma drug delivery. METHOD: All known anti-neoplastic drugs from Martindale's Online Drug Library were systematically reviewed. Martindale, the British National Formulary, OvidSP, and ChemSpider were used to assess neurotoxicity, efficacy, and Blood Brain Barrier (BBB) penetration to generate inclusion/exclusion criteria: criterion 1 excluded neurotoxic agents, but included those associated with systemic side-effects; criterion 2 included efficacious agents in vitro; criterion 3 included agents with no/low in vivo or Phase II/III clinical efficacy; criterion 4 included agents with observed/predicted lack of, or poor BBB penetration. RESULTS: Seventy-seven drugs were excluded due to neurotoxicity, 107 excluded due to poor in vitro efficacy and 68 excluded due to lack of in vivo or clinical efficacy despite good/moderate BBB penetration. Of the remaining 59 drugs, 13 were recommended as good candidates, where lack of in vivo or clinical efficacy may be due to poor BBB penetration. Candidates included carmustine (already delivered as Gliadel), demonstrating proof-of-concept of our review strategy, cilengitide, irinotecan, bevacizumab diaziquone, docetaxel and trabedersen. CONCLUSION: Localised drug delivery candidates were identified using a systematic review strategy which may be applied in the evaluation of future novel experimental or repurposed agents.

INTRODUCTION: Local neurosurgically-applied drug-delivery systems offer an opportunity to target glioblastoma (GBM) residual disease, but consideration must be given to the uptake of delivered agents once diffused from a drug-delivery depot. We assess the glycosaminoglycan-binding enhanced transduction of nanoparticles coated with genetically-engineered peptides, as a direct corollary to biomaterial-based localised drug-delivery systems. METHOD: GBM cells were transduced with biocompatible iron oxide magnetic nanoparticles (dMNP) coated with membrane docking (P21) and cell penetrating (8R) peptides. Protein transduction efficiency was determined by cytochemical staining and metabolic assays. To test the efficacy of the cytotoxic peptide SHEPHERDIN (SHEP), which disrupts the interaction of Survivin with HSP 90, GBM cells were exposed to acute doses of dMNP-P21-8R-SHEP and effects on metabolism measured. RESULTS: Nuclear and cytoplasmic protein transduction of dMNP-8R-P21 was evident in 100% of adult and paediatric GBM cells after 3h exposure, whereas after 16h, only 25% of uncoated nanoparticles traverse the cellular membrane by direct translocation and/or endocytosis. Protein-mediated transduction of dMNP-P21-8R-SHEP results in dose-dependent proliferation impairment of adult and paediatric GBM cells (IC50 25 µM and 20 µM respectively). CONCLUSION: Protein-mediated cellular transduction via membrane docking and cell penetrating peptides has the potential to deliver anti-cancer cargos to brain tumours and diversifies nanoparticle functionality. Early findings characterising SHEP-mediated GBM viability loss and controlled release of dMNP-P21-8R-SHEP from a polymeric microparticle drug-delivery matrix will be discussed.

A dual thermoresponsive and magnetic colloidal gel matrix is described for enhanced stem-cell culture. The combined properties of the material allow enzyme-free passaging and expansion of mesenchymal stem cells, as well as isolation of cells postculture by the simple process of lowering the temperature and applying an external magnetic field. The colloidal gel can be reconfigured with thermal and magnetic stimuli to allow patterning of cells in discrete zones and to control movement of cells within the porous matrix during culture.

Introduction The median survival of patients with glioblastoma multiforme (astrocytoma grade 4) remains less than 18 months despite radical surgery, radiotherapy and systemic chemotherapy. Surgical implantation of chemotherapy eluting wafers into the resection cavity has been shown to improve length of survival but the current licensed therapy has several drawbacks. This paper investigates in vivo efficacy of a novel drug eluting paste in glioblastoma. Methods Poly(lactic-co-glycolic acid)/poly(ethylene glycol) (PLGA/PEG) self-sintering paste was loaded with the chemotherapeutic agent etoposide and delivered surgically into partially resected tumours in a flank murine glioblastoma xenograft model. Results Surgical delivery of the paste was successful and practical, with no toxicity or surgical morbidity to the animals. The paste was retained in the tumour cavity, and preliminary results suggest a useful antitumour and antiangiogenic effect, particularly at higher doses. Bioluminescent imaging was not affected significantly by the presence of the paste in the tumour. Conclusions Chemotherapy loaded PLGA/PEG paste seems to be a promising technology capable of delivering active drugs into partially resected tumours. The preliminary results of this study suggest efficacy with no toxicity and will lead to larger scale efficacy studies in orthotopic glioblastoma models.

Injectable scaffolds are a class of materials that stimulate the regeneration of functional tissue within the body. These materials are attracting interest in regenerative medicine because they allow tissue repair to occur after minimally invasive administration. From a chemistry perspective these materials present new challenges because they must convert from an injectable material to a solid or gel with appropriate kinetics and without damaging surrounding tissues. Furthermore, the material may have to carry living cells or sensitive drug molecules into the body. The demands placed on these materials have stimulated research into novel chemical and physical mechanisms of forming porous structures within aqueous conditions. This review examines the underlying chemistry of a number of classes of injectable scaffolds and sets out challenges for these materials in the future. Refereed/Peer-reviewed

INTRODUCTION: A thermo-setting biomaterial containing a depot of clinically relevant chemotherapeutics applied to the post-surgical resection cavity offers an opportunity for localised control of residual malignant glioma. Here we evaluate mouldable polymer matrices of poly(lactic-co-glycolic acid)/poly(ethylene glycol) (PLGA/PEG) microparticles for tailored combination drug release. METHOD: Clinically-approved or experimental chemotherapeutics, alone and in combination, were loaded onto PLGA/PEG microparticle matrices, or encapsulated inside PLGA microspheres. Mono- and dual-therapy release rates were measured by liquid chromatography and stability verified by mass spectrometry. Cytotoxicity of released drugs was assessed using patient-derived invasive margin cells and flank mouse xenografts. RESULTS: Temozolomide (TMZ), etoposide (ETO) and methotrexate were released from PLGA/PEG alone or in dual combinations over 2 weeks in vitro, whilst irinotecan, cilengitide and imatinib released over a similar period as monotherapies. Cytotoxicity was not impaired by polymer interaction. Drug encapsulation in PLGA microspheres dampens the rapid burst release. PLGA/PEG overcomes TMZ instability, resulting in a 10-day release where the AIC active component was measured. In vivo ETO release markedly reduced glioma bioluminescence with longer-term survivors relative to resection-only controls. CONCLUSION: We have developed a PLGA-based platform technology to deliver multiple clinically relevant chemotherapy agents, including TMZ, from a single matrix. Prolonged release kinetics can be achieved by drug encapsulating drugs, potentially filling the 3 week therapy gap that currently exists between surgery and radiotherapy commencement.