Phase 1 study of escalating-dose OncoGel® (ReGel®/paclitaxel) depot injection, a controlled-release formulation of paclitaxel, for local management of superficial solid tumor lesions

Local Delivery of Irinotecan to Recurrent GBM Patients at Reoperation Offers a Safe Route of Administration

Glioblastomas are impossible to completely resect and almost always recur at the borders of the resection margin. There is no established chemotherapy regimen available to patients who recur, while systemic treatment is hampered by the blood-brain barrier. Here, we report on the first evaluation in humans of the intraparenchymal injection of irinotecan into the resection cavity after surgical resection of recurrent glioblastoma patients. The cytotoxicity of irinotecan was compared to SN-38 in primary cells from recurrent glioblastoma patients. Irinotecan was injected at multiple (~30) sites of the resection cavity wall at a depth of 3 to 5 mm. SN-38 was more cytotoxic than irinotecan at concentrations below 1 µM due to enzyme kinetics. The intraparenchymal administration of irinotecan was safe, with good wound healing and an absence of swelling, inflammation, or pseudo-abscess formation. The median survival post irinotecan administration was 32.6 weeks. The median overall survival was 30.5 months, with a two-year survival rate of 56%. This study demonstrates that local delivery of irinotecan into the brain parenchyma offers a safe route of administration over systemic delivery in the treatment of recurrent glioblastoma.

Pharmacokinetics of Intramuscularly Administered Thermoresponsive Polymers

Aqueous solutions of some polymers exhibit a lower critical solution temperature (LCST); that is, they form phase-separated aggregates when heated above a threshold temperature. Such polymers found many promising (bio)medical applications, including in situ thermogelling with controlled drug release, polymer-supported radiotherapy (brachytherapy), immunotherapy, and wound dressing, among others. Yet, despite the extensive research on medicinal applications of thermoresponsive polymers, their biodistribution and fate after administration remained unknown. Thus, herein, they studied the pharmacokinetics of four different thermoresponsive polyacrylamides after intramuscular administration in mice. In vivo, these thermoresponsive polymers formed depots that subsequently dissolved with a two-phase kinetics (depot maturation, slow redissolution) with half-lives 2 weeks to 5 months, as depot vitrification prolonged their half-lives. Additionally, the decrease of T_CP of a polymer solution increased the density of the intramuscular depot. Moreover, they detected secondary polymer depots in the kidneys and liver; these secondary depots also followed two-phase kinetics (depot maturation and slow dissolution), with half-lives 8 to 38 days (kidneys) and 15 to 22 days (liver). Overall, these findings may be used to tailor the properties of thermoresponsive polymers to meet the demands of their medicinal applications. Their methods may become a benchmark for future studies of polymer biodistribution.

Nanogels as target drug delivery systems in cancer therapy: A review of the last decade

Cancer is an important cause of morbidity and mortality worldwide, irrespective of the level of human development. Globally, it was estimated that there were 19.3 million new cases of cancer and almost 10 million deaths from cancer in 2020. The importance of prevention, early detection as well as effective cancer therapies cannot be over-emphasized. One of the important strategies in cancer therapy is targeted drug delivery to the specific tumor sites. Nanogels are among the several drug delivery systems (DDS) being explored as potential candidates for targeted drug delivery in cancer therapy. Nanogels, which are new generation, versatile DDS with the possession of dual characteristics of hydrogels and nanoparticles have shown great potential as targeted DDS in cancer therapy. Nanogels are hydrogels with a three-dimensional (3D) tunable porous structure and a particle size in the nanometre range, from 20 to 200 nm. They have been visualized as ideal DDS with enormous drug loading capacity, and high stability. Nanogels can be modified to achieve active targeting and enhance drug accumulation in disease sites. They can be designed to be stimulus-responsive, and react to internal or external stimuli such as pH, temperature, light, redox, thus resulting in the controlled release of loaded drug. This prevents drug accumulation in non-target tissues and minimizes the side effects of the drug. Drugs with severe adverse effects, short circulation half-life, and easy degradability by enzymes, such as anti-cancer drugs, and proteins, are suitable for delivery by chemically cross-linked or physically assembled nanogel systems. This systematic review summarizes the evolution of nanogels for targeted drug delivery for cancer therapy over the last decade. On-going clinical trials and recent applications of nanogels as targeted DDS for cancer therapy will be discussed in detail. The review will be concluded with discussions on safety and regulatory considerations as well as future research prospects of nanogel-targeted drug delivery for cancer therapy.

The Basic Study of Liposome in Temperature-Sensitive Gel at Body Temperature for Treatment of Peritoneal Dissemination

Peritoneal dissemination is a disease that is difficult to treat surgically because it is widely scattered and proliferates in the abdominal cavity. It is a challenge that even if the drug is administered directly into the abdominal cavity, it rapidly disappears from the abdominal cavity, and the therapeutic effect is not optimal, as expected. In this study, for a liposomal paclitaxel in temperature-sensitive gel that is a suspension before administration and a gel after intraperitoneal administration, the antitumor effect of this formulation was evaluated. Temperature-sensitive gels were prepared using methylcellulose, sodium citrate, and macrogol 4000 and mixed with liposomal paclitaxel. Liposomal paclitaxel containing temperature-sensitive gel in the body was administered into the peritoneal cavity of a mouse model of peritoneal dissemination; the number of cells was significantly reduced compared to a paclitaxel solution of liposomal paclitaxel. These results showed that the liposome in temperature-sensitive gel inhibited cell proliferation in the abdominal cavity. This formulation can be administered easily at room temperature, and it gels and remains in the abdominal cavity for a long period, resulting in a more substantial effect than the existing drug.

Toxicology and Pharmacokinetics Study of Intradiscal Injection of Simvastatin in Rabbits

To test the pharmacokinetics and toxicology of whole organs and tissues after intradiscal injection of simvastatin in rabbits. To provide the information needed to support human clinical trials. Twelve male and twelve female rabbits were randomly divided into four groups: control group (0 mg/ml), low dose group (0.1 mg/ml), medium dose group (1 mg/ml) and high dose group (10 mg/ml). Simvastatin at different concentrations of 10 μl was injected into L3/4, L4/5 and L5/6 intervertebral discs in each group. Poly (ethylene glycol) -poly (lactic-co-glycolic acid) -poly (ethylene glycol) (PEG-PLGA-PEG) polymer as the drug carrier. The pharmacokinetics of blood samples were measured by LC-MS/MS. Cerebrospinal fluid was obtained and the drug concentration was measured. Blood routine, blood biochemistry and urine of all animals were analyzed and evaluated. The heart, kidney, liver and spleen of each animal were observed and weighed. The intervertebral disc tissues were stained with hematoxylin and hematoxylin (H&E), and then qualitatively analyzed by optical microscopy. 28 days after intradiscal injection of simvastatin, 28 days after simvastatin intradiscal injection, there was no significant difference between the weight, food residue, blood routine, blood biochemistry, urine routine results and the weight of each organ in the four groups (p > 0.05). The serum concentration of simvastatin is lower than the lowest measurable concentration. The histological score of the intervertebral disc in the high-dose group was significantly higher than that in the other three groups at 28 days (p < 0.05). Three doses of simvastatin were injected into male and female animals respectively, showing no toxic effects. Microscopic histological evaluation of the intervertebral disc showed that the high dose group (10 mg/ml) had damage to the intervertebral disc tissue.

Recent Advances of Taxol-Loaded Biocompatible Nanocarriers Embedded in Natural Polymer-Based Hydrogels

The discovery of paclitaxel (PTX) has been a milestone in anti-cancer therapy and has promoted the development and marketing of various formulations that have revolutionized the therapeutic approach towards several malignancies. Despite its peculiar anti-cancer activity, the physico-chemical properties of PTX compromise the administration of the compound in polar media. Because of this, since the development of the first Food and Drug Administration (FDA)-approved formulation (Taxol®), consistent efforts have been made to obtain suitable delivery systems able to preserve/increase PTX efficacy and to overcome the side effects correlated to the presence of some excipients. The exploitation of natural polymers as potential materials for drug delivery purposes has favored the modulation of the bioavailability and the pharmacokinetic profiles of the drug, and in this regard, several formulations have been developed that allow the controlled release of the active compound. In this mini-review, the recent advances concerning the design and applications of natural polymer-based hydrogels containing PTX-loaded biocompatible nanocarriers are discussed. The technological features of these formulations as well as the therapeutic outcome achieved following their administration will be described, demonstrating their potential role as innovative systems to be used in anti-tumor therapy.

Drug delivery and targeting to brain tumors: considerations for crossing the blood-brain barrier

Introduction: The blood-brain barrier (BBB) selectively impedes the transportation of drug molecules into the brain, which makes the drug delivery and targeting of brain tumors very challenging.Areas covered: Having surveyed the recent literature, comprehensive insights are given into the impacts of the BBB on the advanced drug delivery and targeting modalities for brain tumors.Expert opinion: Brain capillary endothelial cells form the BBB in association with astrocytes, pericytes, neurons, and extracellular matrix. Coop of these forms the complex setting of neurovascular unite. The BBB maintains the brain homeostasis by restrictive controlling of the blood circulating nutrients/substances trafficking. Despite substantial progress on therapy of brain tumors, there is no impeccable strategy to safely deliver chemotherapeutics into the brain. Various strategies have been applied to deliver chemotherapeutics into the brain (e.g. BBB opening, direct delivery by infusion, injection, microdialysis, and implants, and smart nanosystems), which hold different pros and cons. Of note, smart nanoscale multifunctional nanomedicines can serve as targeting, imaging, and treatment modality for brain tumors. Given that aggressive brain tumors (e.g. gliomas) are often unresponsive to any treatments, an in-depth understanding of the molecular/cellular complexity of brain tumors might help the development of smart and effective treatment modalities.

Brain Drug Delivery: Overcoming the Blood-brain Barrier to Treat Tauopathies

Tauopathies are neurodegenerative disorders characterized by the deposition of abnormal tau protein in the brain. The application of potentially effective therapeutics for their successful treatment is hampered by the presence of a naturally occurring brain protection layer called the blood-brain barrier (BBB). BBB represents one of the biggest challenges in the development of therapeutics for central nervous system (CNS) disorders, where sufficient BBB penetration is inevitable. BBB is a heavily restricting barrier regulating the movement of molecules, ions, and cells between the blood and the CNS to secure proper neuronal function and protect the CNS from dangerous substances and processes. Yet, these natural functions possessed by BBB represent a great hurdle for brain drug delivery. This review is concentrated on summarizing the available methods and approaches for effective therapeutics' delivery through the BBB to treat neurodegenerative disorders with a focus on tauopathies. It describes the traditional approaches but also new nanotechnology strategies emerging with advanced medical techniques. Their limitations and benefits are discussed.

Self-Assemblable Polymer Smart-Blocks for Temperature-Induced Injectable Hydrogel in Biomedical Applications

Self-assembled temperature-induced injectable hydrogels fabricated via self-assembly of polymer smart-blocks have been widely investigated as drug delivery systems and platforms for tissue regeneration. Polymer smart-blocks that can be self-assembly play an important role in fabrication of hydrogels because they can self-assemble to induce the gelation of their copolymer in aqueous solution. The self-assembly occurs in response to an external stimulus change, such as temperature, pH, glucose, ionic strength, light, magnetic field, electric field, or their combination, which results in property transformations like hydrophobicity, ionization, and conformational change. The self-assembly smart-block based copolymers exist as a solution in aqueous media at certain conditions that are suitable for mixing with bioactive molecules and/or cells. However, this solution turns into a hydrogel due to the self-assembly of the smart-blocks under exposure to an external stimulus change in vitro or injection into the living body for a controllable release of loaded bioactive molecules or serving as a biomaterial scaffold for tissue regeneration. This work reports current scenery in the development of these self-assembly smart-blocks for fabrication of temperature-induced injectable physically cross-linked hydrogels and their potential application as drug delivery systems and platforms for tissue engineering.

Overcoming the Blood–Brain Barrier. Challenges and Tricks for CNS Drug Delivery

Treatment of certain central nervous system disorders, including different types of cerebral malignancies, is limited by traditional oral or systemic administrations of therapeutic drugs due to possible serious side effects and/or lack of the brain penetration and, therefore, the efficacy of the drugs is diminished. During the last decade, several new technologies were developed to overcome barrier properties of cerebral capillaries. This review gives a short overview of the structural elements and anatomical features of the blood–brain barrier. The various in vitro (static and dynamic), in vivo (microdialysis), and in situ (brain perfusion) blood–brain barrier models are also presented. The drug formulations and administration options to deliver molecules effectively to the central nervous system (CNS) are presented. Nanocarriers, nanoparticles (lipid, polymeric, magnetic, gold, and carbon based nanoparticles, dendrimers, etc.), viral and peptid vectors and shuttles, sonoporation and microbubbles are briefly shown. The modulation of receptors and efflux transporters in the cell membrane can also be an effective approach to enhance brain exposure to therapeutic compounds. Intranasal administration is a noninvasive delivery route to bypass the blood–brain barrier, while direct brain administration is an invasive mode to target the brain region with therapeutic drug concentrations locally. Nowadays, both technological and mechanistic tools are available to assist in overcoming the blood–brain barrier. With these techniques more effective and even safer drugs can be developed for the treatment of devastating brain disorders.

A tumor responsive self healing prodrug hydrogel enables synergistic action of doxorubicin and miltefosine for focal combination chemotherapy

Targeted therapy that facilitates the on-site, on-demand action of drug combinations is a promising approach for combination chemotherapy.

Biopolymers for Antitumor Implantable Drug Delivery Systems: Recent Advances and Future Outlook

In spite of remarkable improvements in cancer treatments and survivorship, cancer still remains as one of the major causes of death worldwide. Although current standards of care provide encouraging results, they still cause severe systemic toxicity and also fail in preventing recurrence of the disease. In order to address these issues, biomaterial-based implantable drug delivery systems (DDSs) have emerged as promising therapeutic platforms, which allow local administration of drugs directly to the tumor site. Owing to the unique properties of biopolymers, they have been used in a variety of ways to institute biodegradable implantable DDSs that exert precise spatiotemporal control over the release of therapeutic drug. Here, the most recent advances in biopolymer-based DDSs for suppressing tumor growth and preventing tumor recurrence are reviewed. Novel emerging biopolymers as well as cutting-edge polymeric microdevices deployed as implantable antitumor DDSs are discussed. Finally, a review of a new therapeutic modality within the field, which is based on implantable biopolymeric DDSs, is given.

Hydrogel formulations for biologicals: current spotlight from a commercial perspective

Hydrogels are, from a commercial perspective especially because of their ease of production, attractive sustained-release systems for high potent immunoglobulins with short circulation half-lives. Hydrogel formulations can reduce the dosing frequency while maintaining therapeutically relevant drug concentrations locally as well as systemically. However, hydrogels have only limited loading capacities and release hydrophilic immunoglobulins typically within hours or days, whereas weeks or months would be more preferable. Despite an evident medical need, the call for novel depot formulations seems to go unheard. This special report explores sought-after hydrogel properties, discusses arguments for using established versus novel excipients and provides selected examples for hydrogel formulations of biologicals that have proceeded into clinical development.

EUS-guided paclitaxel injection as an adjunctive therapy to systemic chemotherapy and concurrent external beam radiation before surgery for localized or locoregional esophageal cancer: a multicenter prospective randomized trial

BACKGROUND AND AIMS

OncoGel (Protherics Salt Lake City, Inc, Salt Lake City, UT) is paclitaxel (PTX) formulated in a thermosensitive, biodegradable copolymer for focused cytotoxicity and radiosensitization. A phase 2a study suggested that EUS-guided PTX injection into esophageal tumors subsequently receiving radiotherapy was safe.

METHODS

In an international multicenter, prospective, randomized phase 2b study, patients with local or locoregional adenocarcinoma or squamous cell carcinoma (SCC) of the esophagus/gastroesophageal junction and eligible for neoadjuvant chemoradiotherapy (CRT) before surgery were randomized to standard of care (SOC) plus EUS-guided PTX injection or SOC alone. PTX was injected in 0.5 to 1.0 mL aliquots throughout the tumor. Planned CRT as SOC was intravenous 5-fluorouracil for the first 4 days (weeks 1 and 5), intravenous cisplatin on the first day of each 5-fluorouracil course, and radiotherapy over 5.5 weeks. Patients were evaluated weekly during CRT and re-evaluated at 12 weeks for surgical eligibility and CT for change in overall tumor volume.

RESULTS

The analysis included 137 patients (97 males; mean age, 58 ± 9.1 years) randomized to PTX + SOC (n = 72) and SOC (n = 65) by using a modified intention-to-treat approach. Overall response by tumor volume between the PTX (12.5%) and the SOC group (20.0%; P = .24; odds ratio, 0.57; 95% confidence interval, 0.23-1.44) was similar. Pathologic complete response was higher in the SOC group (26.2% vs 12.5%; P = .046); however, 12-month survival (P = .412) and the overall frequency of 1 or more adverse events (P = .17) were similar between the 2 groups.

CONCLUSIONS

SOC + PTX is safe but does not improve overall survival or overall tumor response at the primary tumor site for patients with local or locoregional cancer of the esophagus/gastroesophageal junction. (Clinical trial registration number: NCT00573131.).

Laparoscopic subperitoneal injection of chemo-loaded particles lowers tumor growth on a rabbit model of peritoneal carcinomatosis

The purpose of our study was to assess the effect of controlled-release chemotherapy on the growth and viability of peritoneal carcinomatosis treated by subperitoneal injection in a rabbit VX2 model. A model of peritoneal carcinomatosis was created by laparoscopic injection of VX2 tumor in the left and right broad ligaments of 12 White New Zealand rabbits. At day 12, each tumor was randomly treated with a peritumoral injection of 0.5 mL microspheres loaded with doxorubicin (DEM-DOX) or unloaded (DEM-BLAND). Seven days after treatment, tumor volume, tumor viability in histology, local tumor necrosis in contact with DEM, and doxorubicin concentration profile around the drug eluting microspheres (DEM) were measured. Tumor volume was significantly lower in the DEM-DOX group (3.6 ± 3.2 cm³) compared with the DEM-BLAND group (8.9 ± 5.4 cm³) (p = 0.0425). The percentage of viable tumor tissue was significantly lower in the DEM-DOX group (38% ± 17%) compared with the DEM-BLAND group (56% ± 20%) (p = 0.0202). Tissue necrosis was observed around all DEM-DOX up to a distance of 1.094 ± 0.852 mm and never observed around DEM-BLAND. Drug concentration was above the therapeutic level of 1.0 µM up to a distance of 1.4 mm from the DEM to the tumor. Laparoscopic subperitoneal injection of chemo-loaded particles is feasible and lowers tumor growth and viability in a rabbit model of peritoneal carcinomatosis after 1 week.

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.

Modified PLGA–PEG–PLGA thermosensitive hydrogels with suitable thermosensitivity and properties for use in a drug delivery system

PLGA–PEG–PLGA (PPP) triblock copolymer is the most widely studied thermosensitive hydrogel owing to its non-toxic, biocompatible, biodegradable, and thermosensitive properties.

Injectable formulations of poly(lactic acid) and its copolymers in clinical use

Poly(lactic acid) and its copolymers have revolutionized the field of drug delivery due to their excellent biocompatibility and tunable physico-chemical properties. These copolymers have served the healthcare sector by contributing many products to combat various diseases and for biomedical applications. This article provides a comprehensive overview of clinically used products of poly(lactic acid) and its copolymers. Multi-dimension information covering product approval, formulation aspects and clinical status is described to provide a panoramic overview of each product. Moreover, leading patented technologies and various clinical trials on these products for different applications are included. This review focuses on marketed injectable formulations of PLA and its copolymers.

Polylactic acid (PLA) controlled delivery carriers for biomedical applications

Polylactic acid (PLA) and its copolymers have a long history of safety in humans and an extensive range of applications. PLA is biocompatible, biodegradable by hydrolysis and enzymatic activity, has a large range of mechanical and physical properties that can be engineered appropriately to suit multiple applications, and has low immunogenicity. Formulations containing PLA have also been Food and Drug Administration (FDA)-approved for multiple applications making PLA suitable for expedited clinical translatability. These biomaterials can be fashioned into sutures, scaffolds, cell carriers, drug delivery systems, and a myriad of fabrications. PLA has been the focus of a multitude of preclinical and clinical testing. Three-dimensional printing has expanded the possibilities of biomedical engineering and has enabled the fabrication of a myriad of platforms for an extensive variety of applications. PLA has been widely used as temporary extracellular matrices in tissue engineering. At the other end of the spectrum, PLA's application as drug-loaded nanoparticle drug carriers, such as liposomes, polymeric nanoparticles, dendrimers, and micelles, can encapsulate otherwise toxic hydrophobic anti-tumor drugs and evade systemic toxicities. The clinical translation of these technologies from preclinical experimental settings is an ever-evolving field with incremental advancements. In this review, some of the biomedical applications of PLA and its copolymers are highlighted and briefly summarized.

Preclinical Safety Evaluation in Rats of a Polymeric Matrix Containing an siRNA Drug Used as a Local and Prolonged Delivery System for Pancreatic Cancer Therapy

Conventional chemotherapy treatments for pancreatic cancer are mainly palliative. RNA interference (RNAi)-based drugs present the potential for a new targeted treatment. LOcal Drug EluteR (LODER(TM)) is a novel biodegradable polymeric matrix that shields drugs against enzymatic degradation and releases small interfering RNA (siRNA) against G12D-mutated KRAS (siG12D). siG12D-LODER has successfully passed a phase 1/2a clinical trial. Such a formulation necessitates biocompatibility and safety studies. We describe the safety and toxicity studies with siG12D-LODER in 192 Hsd:Sprague Dawley rats, after repeated subcutaneous administrations (days 1, 14, and 28). Animals were sacrificed on days 29 and 42 (recovery phase). In all groups, no adverse effects were noted, and all animals showed favorable local and systemic tolerability. Histopathologically, LODER implantation resulted in the expected capsule formation, composed of a thin fibrotic tissue. On the interface between the cavity and the capsule, a single layer composed of macrophages and multinucleated giant cells was observed. No difference was noted between the placebo and siG12D-LODER groups. These findings provide valuable information for future preclinical studies with siRNA-bearing biodegradable polymers and for the safety aspects of RNAi-based drugs as a targeted therapy.

Principles of pharmacotherapy

This chapter will review the challenges in pharmacotherapy in primary brain tumors that include the presence of the blood-brain barrier, a blood-tumor barrier, active drug efflux pumps, and high plasma protein binding of agents. The approaches to improve the delivery of drugs to the brain will be discussed. Often the management of brain tumors involves the use of corticosteroids and enzyme-inducing antiseizure medications that can have significant drug interactions that may impact the efficacy or toxicity of drugs used to treat these patients. Various techniques used to assess drug distribution to the brain will be reviewed.

Engineered in-situ depot-forming hydrogels for intratumoral drug delivery

Chemotherapy is the traditional treatment for intermediate and late stage cancers. The search for treatment options with minimal side effects has been ongoing for several years. Drug delivery technologies that result in minimal or no side effects with improved ease of use for the patients are receiving increased attention. Polymer drug conjugates and nanoparticles can potentially offset the volume of drug distribution while enhancing the accumulation of the active drug in tumors thereby reducing side effects. Additionally, development of localized drug delivery platforms is being investigated as another key approach to target tumors with minimal or no toxicity. Development of in-situ depot-forming gel systems for intratumoral delivery of immuno-oncology actives can enhance drug bioavailability to the tumor site and reduce systemic toxicity. This field of drug delivery is critical to develop given the advent of immunotherapy and the availability of novel biological molecules for treating solid tumors. This article reviews the advances in the field of engineered in-situ gelling platforms as a practical tool for local delivery of active oncolytic agents to tumor sites.

Hot melt extruded and injection moulded disulfiram-loaded PLGA millirods for the treatment of glioblastoma multiforme via stereotactic injection

Glioblastoma multiforme (GBM) has a poor prognosis and is one of the most common primary malignant brain tumours in adults. Stereotactic injections have been used to deliver chemotherapeutic drugs directly into brain tumours. This paper describes the development of disulfiram (DSF)-loaded biodegradable millirods manufactured using hot melt extrusion (HME) and injection moulding (IM). The paper demonstrates that the stability of the DSF within the millirods is dependent on the manufacturing technique used as well as the drug loading. The physical state of the DSF within the millirods was dependent on the fabrication process, with the DSF in the HME millirods being either completely amorphous within the PLGA, while the DSF within the IM millirods retained between 54 and 66% of its crystallinity. Release of DSF from the millirods was dependent on the degradation rate of the PLGA, the manufacturing technique used as well as the DSF loading. DSF in the 10% (w/w) DSF loaded HME millirods and the 20% (w/w) DSF-loaded HME and IM millirods had a similar cytotoxicity against a GBM cell line compared to the unprocessed DSF control. However, the 10% (w/w) DSF-loaded IM millirods had a significantly lower cytotoxicity when compared to the unprocessed control.

Current strategies for targeted delivery of bio-active drug molecules in the treatment of brain tumor

Brain tumor is one of the most challenging diseases to treat. The major obstacle in the specific drug delivery to brain is blood-brain barrier (BBB). Mostly available anti-cancer drugs are large hydrophobic molecules which have limited permeability via BBB. Therefore, it is clear that the protective barriers confining the passage of the foreign particles into the brain are the main impediment for the brain drug delivery. Hence, the major challenge in drug development and delivery for the neurological diseases is to design non-invasive nanocarrier systems that can assist controlled and targeted drug delivery to the specific regions of the brain. In this review article, our major focus to treat brain tumor by study numerous strategies includes intracerebral implants, BBB disruption, intraventricular infusion, convection-enhanced delivery, intra-arterial drug delivery, intrathecal drug delivery, injection, catheters, pumps, microdialysis, RNA interference, antisense therapy, gene therapy, monoclonal/cationic antibodies conjugate, endogenous transporters, lipophilic analogues, prodrugs, efflux transporters, direct conjugation of antitumor drugs, direct targeting of liposomes, nanoparticles, solid-lipid nanoparticles, polymeric micelles, dendrimers and albumin-based drug carriers.

Biodegradable thermogelling polymers: working towards clinical applications

As society ages, aging medical problems such as organ damage or failure among senior citizens increases, raising the demand for organ repair technologies. Synthetic materials have been developed and applied in various parts of human body to meet the biomedical needs. Hydrogels, in particular, have found extensive applications as wound healing, drug delivery and controlled release, and scaffold materials in the human body. The development of the next generation of soft hydrogel biomaterials focuses on facile synthetic methods, efficacy of treatment, and tunable multi-functionalities for applications. Supramolecular 3D entities are highly attractive materials for biomedical application. They are assembled by modules via various non-covalent bonds (hydrogen bonds, p-p stacking and/or van der Waals interactions). Biodegradable thermogels are a class of such supramolecular assembled materials. Their use as soft biomaterials and their related applications are described in this Review.

Current approaches to enhance CNS delivery of drugs across the brain barriers

Although many agents have therapeutic potentials for central nervous system (CNS) diseases, few of these agents have been clinically used because of the brain barriers. As the protective barrier of the CNS, the blood–brain barrier and the blood–cerebrospinal fluid barrier maintain the brain microenvironment, neuronal activity, and proper functioning of the CNS. Different strategies for efficient CNS delivery have been studied. This article reviews the current approaches to open or facilitate penetration across these barriers for enhanced drug delivery to the CNS. These approaches are summarized into three broad categories: noninvasive, invasive, and miscellaneous techniques. The progresses made using these approaches are reviewed, and the associated mechanisms and problems are discussed.

Bioengineering strategies for designing targeted cancer therapies

The goals of bioengineering strategies for targeted cancer therapies are (1) to deliver a high dose of an anticancer drug directly to a cancer tumor, (2) to enhance drug uptake by malignant cells, and (3) to minimize drug uptake by nonmalignant cells. Effective cancer-targeting therapies will require both passive- and active-targeting strategies and a thorough understanding of physiologic barriers to targeted drug delivery. Designing a targeted therapy includes the selection and optimization of a nanoparticle delivery vehicle for passive accumulation in tumors, a targeting moiety for active receptor-mediated uptake, and stimuli-responsive polymers for control of drug release. The future direction of cancer targeting is a combinatorial approach, in which targeting therapies are designed to use multiple-targeting strategies. The combinatorial approach will enable combination therapy for delivery of multiple drugs and dual ligand targeting to improve targeting specificity. Targeted cancer treatments in development and the new combinatorial approaches show promise for improving targeted anticancer drug delivery and improving treatment outcomes.

rhEGF-containing thermosensitive and mucoadhesive polymeric sol–gel for endoscopic treatment of gastric ulcer and bleeding

Gastrointestinal endoscopy is a standard diagnostic tool for gastrointestinal ulcers and cancer. In this study, we have developed recombinant human epidermal growth factor-containing ulcer-coating polymeric sol–gel for endoscopic application. Chitosan and pluronic F127 were employed for their thermoresponsive and bioadhesive properties. At temperatures below 21℃, polymeric sol–gel remains liquid during endoscopic application and transforms to gel at body temperature after application on ulcers. In an in vitro cellular wounding assay, recombinant human epidermal growth factor sol–gel significantly enhanced the cell migration and decreased the wounding area (68%) compared to nontreated, recombinant human epidermal growth factor solution, and sol–gel without recombinant human epidermal growth factor (42, 49, and 32 % decreased at day 1). The in vivo ulcer-healing study was performed in an acetic acid-induced gastric ulcer rat model and proved that our recombinant human epidermal growth factor endoscopic sol–gel facilitated the ulcer-healing process more efficiently than the other treatments. Ulcer sizes in the recombinant human epidermal growth factor sol–gel group were decreased 2.9- and 2.1-fold compared with those in the nontreated group on days 1 and 3 after ulceration, respectively. The mucosal thickness in the recombinant human epidermal growth factor sol–gel group was significantly increased compared to that in the nontreated group (3.2- and 6.9-fold on days 1 and 3 after ulceration, respectively). In a gastric retention study, recombinant human epidermal growth factor sol–gel stayed on the gastric mucosa more than 2 h after application. The present study suggests that recombinant human epidermal growth factor sol–gel is a prospective candidate for treating gastric ulcers via endoscopic application.

Injectable implants for the sustained release of protein and peptide drugs

Protein and peptide macromolecules have emerged as promising therapeutic agents in recent years. However, their delivery to the target site can be challenging owing to their susceptibility to denaturation and degradation, short half-life and, therefore, poor bioavailability. In situ-forming implants present an attractive parenteral delivery platform for proteins and peptides because of their ease of application, sustained-release properties, tissue biocompatibility and simple manufacture. In this review, we discuss the various mechanisms by which polymer systems assemble in situ to form implant devices for sustained release of therapeutic macromolecules, and highlight recent advances in polymer systems that gel in response to a combination of these mechanisms. Finally, we examine release mechanisms, marketed products and limitations of injectable implants.

A reconstituted "two into one" thermosensitive hydrogel system assembled by drug-loaded amphiphilic copolymer nanoparticles for the local delivery of paclitaxel

Combination delivery systems composed of injectable hydrogels and drug-incorporated micelles or nanoparticles with tunable and convenient properties for clinical operation and storage are urgently demanded in regional cancer chemotherapy to prolong and control drug release, enhance antitumor efficiency and decrease side effects. Previously, we developed a novel thermosensitive amphiphilic triblock copolymer, poly(ε-caprolactone-co-1,4,8-trioxa[4.6]spiro-9-undecanone)-poly(ethylene glycol)-poly(ε-caprolactone-co-1,4,8-trioxa[4.6]spiro-9-undecanone) (PECT), and fabricated a reconstituted "two into one" combination system of thermosensitive injectable hydrogel PTX/PECT^Gel, assembled from paclitaxel (PTX)-loaded PECT nanoparticles (NPs). PTX/PECT^Gel could be stored as freeze-dried powders of paclitaxel-loaded PECT NPs, which could be reconstituted into aqueous fluid dispersions at ambient temperature just by mixing with water after gentle stirring for several minutes, and form a hydrogel at the injected site in vivo. Herein, the drug release, in vivo morphology, antitumor efficiency and pharmacokinetic properties of PTX/PECT^Gel were evaluated. The PTX/PECT^Gel combination system could continuously release PTX in a near linear manner over 42 days in vitro, and simultaneously, PTX/PECT NPs containing 75% of the total released PTX could dissociate from the PTX/PECT^Gel. PTX/PECT^Gel exhibited remarkable in vitro anti-proliferative activities against Ehrlich ascites carcinoma (EAC) cancer cells. The peritumorally or intratumorally injected PECT gel could cover the entire surface or fill up the interior space of the tumor, respectively. A single peritumoral injection of the PTX/PECT^Gel formulation at a low dosage of 10 mg kg^-1 could completely inhibit the growth of an EAC tumor inoculated in Balb/c mice after the first week, and the inhibition could be sustained for more than 21 days. The plasma pharmacokinetic study demonstrated that PTX/PECT^Gel could greatly decrease the systemic exposure of PTX, as confirmed by the rather low plasma concentration. On the other hand, the PTX concentration in normal tissues with the intratumoral injection of PTX/PECT^Gel was approximately 2 μg g^-1, which was 3-10 times lower than that with the intraperitoneal or intratumoral injection of Taxol®, implying fewer off-target side effects. These data confirmed that the PTX/PECT^Gel combination local delivery system could vastly prolong the in vitro and in vivo paclitaxel release, enhance the local tumor inhibition effect and lower the systemic exposure and tissue distribution of paclitaxel. Hence, the "two into one" PTX/PECT^Gel system holds underlying value for regional cancer chemotherapy.

Endoscopic ultrasound-guided antitumor agents

The development of linear-array endoscopic ultrasonography (EUS), with its real-time guidance of needle advancement, changed EUS from a diagnostic procedure to an interventional procedure. EUS-guided fine-needle injection (EUS-FNI) is an attractive minimally invasive delivery system with potential applications in local (intratumoral) and combination therapy against esophageal and pancreatic cancers. The evidence of the feasibility of EUS-FNI of antitumor agents has been expanding with promising results.

Local drug delivery strategies for cancer treatment: gels, nanoparticles, polymeric films, rods, and wafers

Polymer-based drug delivery depots have been investigated over the last several decades as a means to improve upon the lack of tumor targeting and severe systemic morbidities associated with intravenous chemotherapy treatments. These localized therapies exist in a variety of form factors designed to facilitate the delivery of drug directly to the site of disease in a controlled manner, sparing off-target tissue toxicities. Many of these depots are biodegradable and designed to maintain therapeutic concentrations of drug at the tumor site for a prolonged period of time. Thus a single implantation procedure is required, sometimes coincident with tumor excision surgery, and thereby biodegrading following complete release of the loaded active agent. Even though localized polymer depot delivery systems have been investigated, a surprisingly small subset of these technologies has demonstrated potentially curative preclinical results for cancer applications, and fewer have progressed toward commercialization. The aims of this article are to review the most well-studied and efficacious local polymer delivery systems from the last two decades, to examine the rationale for utilizing drug-eluting polymer implants in cancer patients, and to identify the patient cohorts that could most benefit from localized therapy. Finally, a discussion of the physiological barriers to localized therapy (i.e. drug penetration, transport), technical hurdles, and future outlook of the field is presented.

Low-molecular-weight methylcellulose-based thermo-reversible gel/pluronic micelle combination system for local and sustained docetaxel delivery

PURPOSE

To develop low-molecular-weight methylcellulose (LMw MC)-based gel/Pluronic F127 micelle combination system for local and sustained delivery of docetaxel (DTX).

METHODS

LMw MC and Pluronic F127 were used to formulate an injectable thermo-reversible gel/micelle combination system containing DTX. The DTX-loaded combination system was characterized and its therapeutic efficacy evaluated in a subcutaneous tumor model.

RESULTS

Mixtures of LMw MC, AS, and Pluronic F127 formed gel at ~15-40°C depending on AS concentration. The combination system released DTX for >30 days with a biphasic and sustained release pattern, and DTX stability was maintained during release. The combination system significantly enhanced anti-cancer effects of DTX and prolonged survival of the model mouse in comparison with free DTX.

CONCLUSIONS

The LMw MC gel/Pluronic F127 micelle combination system constitutes a promising tool for reducing tumor size and eradicating remaining tumor cells before and after surgery.

Matrix metalloproteinase-sensitive thermogelling polymer for bioresponsive local drug delivery

Development of a successful bioresponsive drug delivery system requires exquisite engineering of the materials so that they are able to respond to signals stemming from the physiological environment. In this study we propose a new Pluronic(®) based thermogelling system containing matrix metalloproteinase-2 (MMP2) responsive peptide sequences. A novel thermosensitive multiblock co-polymer comprising an MMP2-labile octapeptide (Gly-Pro-Val-Gly-Leu-Ile-Gly-Lys) was synthesized from a Pluronic(®) triblock co-polymer. The polymer was designed to form a thermogel at body temperature and degrade in the presence of MMP overexpressed in a tumor. The synthesized polymer was a multiblock co-polymer with ∼2.5 U of Pluronic(®). The multiblock co-polymer solutions exhibited reverse thermal gelation around body temperature. The gelation temperatures of the multiblock co-polymer solutions were lower than those of the corresponding Pluronic(®) monomer at a particular concentration. The cytotoxicity of the synthesized polymer was lower compared with the monomer. The solubility of the hydrophobic anticancer drug paclitaxel was enhanced in the polymer solutions by micelle formation. The synthesized polymer was preferentially degraded in the presence of MMP. Paclitaxel release was dependent on the enzyme concentration. These findings suggest that the synthesized polymer has potential as a controlled drug delivery system due to its unique phase transition and bioresponsive behavior.