Paclitaxel-eluting polymer film reduces locoregional recurrence and improves survival in a recurrent sarcoma model: a novel investigational therapy

FBXO22 is a potential therapeutic target for recurrent chondrosarcoma

Chondrosarcoma (CHS) is a malignant bone tumor with insensitivity to both radiotherapy and chemotherapy, and a high recurrence rate. However, the latent mechanism of recurrent CHS (Re-CHS) remains elusive. Here, we discovered that FBXO22 was highly expressed in clinical samples of Re-CHS. FBXO22 played a significant role in various cancers. However, the role of FBXO22 in Re-CHS remained unclear. Our research demonstrated that suppressing FBXO22 abated the proliferation and migration of CHS cells and facilitated their apoptosis. In addition, suppressing FBXO22 raised the expression of PD-L1 in Re-CHS. All these findings provide new evidence for using FBXO22 and PD-L1 as combined targets to prevent and treat Re-CHS, which may prove to be a novel strategy for immunotherapy of CHS, especially Re-CHS.

Exploring the vast potentials and probable limitations of novel and nanostructured implantable drug delivery systems for cancer treatment

Conventional cancer chemotherapy regimens, albeit successful to some extent, suffer from some significant drawbacks, such as high-dose requirements, limited bioavailability, low therapeutic indices, emergence of multiple drug resistance, off-target distribution, and adverse effects. The main goal of developing implantable drug delivery systems (IDDS) is to address these challenges and maintain anti-cancer drugs directly at the intended sites of therapeutic action while minimizing inevitable side effects. IDDS possess numerous advantages over conventional drug delivery, including controlled drug release patterns, one-time drug administration, as well as loading and stabilizing poorly water-soluble chemotherapy drugs. Here, we summarized conventional and novel (three-dimensional (3D) printing and microfluidic) preparation techniques of different IDDS, including nanofibers, films, hydrogels, wafers, sponges, and osmotic pumps. These systems could be designed with high biocompatibility and biodegradability features using a wide variety of natural and synthetic polymers. We also reviewed the published data on these systems in cancer therapy with a particular focus on their release behavior. Various release profiles could be attained in IDDS, which enable predictable, adjustable, and sustained drug releases. Furthermore, multi-step or stimuli-responsive drug release could be obtained in these systems. The studies mentioned in this article have proven the effectiveness of IDDS for treating different cancer types with high prevalence, including breast cancer, and aggressive cancer types, such as glioblastoma and liver cancer. Additionally, the challenges in applying IDDS for efficacious cancer therapy and their potential future developments are also discussed. Considering the high potential of IDDS for further advancements, such as programmable release and degradation features, further clinical trials are needed to ensure their efficiency. The overall goal of this review is to expand our understanding of the behavior of commonly investigated IDDS and to identify the barriers that should be addressed in the pursuit of more efficient therapies for cancer. See also the graphical abstract(Fig. 1).

High dose, dual-release polymeric films for extended surgical bed paclitaxel delivery

While surgery represents a major therapy for most solid organ cancers, local recurrence is clinically problematic for cancers such as sarcoma for which adjuvant radiotherapy and systemic chemotherapy provide minimal local control or survival benefit and are dose-limited due to off-target side effects. We describe an implantable, biodegradable poly(1,2-glycerol carbonate) and poly(caprolactone) film with entrapped and covalently-bound paclitaxel enabling safe, controlled, and extended local delivery of paclitaxel achieving concentrations 10,000× tissue levels compared to systemic administration. Films containing entrapped and covalently-bound paclitaxel implanted in the tumor bed, immediately after resection of human cell line-derived chondrosarcoma and patient-derived xenograft liposarcoma and leiomyosarcoma in mice, improve median 90- or 200-day recurrence-free and overall survival compared to control mice. Furthermore, mice in the experimental film arm show no film-related morbidity. Continuous, extended, high-dose paclitaxel delivery via this unique polymer platform safely improves outcomes in three different sarcoma models and provides a rationale for future incorporation into human trials.

Synthesis of Polyethylene Glycol-Poly(glycerol carbonate) Block Copolymeric Micelles as Surfactant-Free Drug Delivery Systems

We report the synthesis of block copolymers of monomethoxylated polyethylene glycol and poly(glycerol carbonate) (mPEG-b-PGC) via the ring-opening polymerization of benzyl glycidyl ether, monomethoxylated polyethylene glycol, and carbon dioxide using a cobalt salen catalyst. The resulting block copolymers display high polymer/cyclic carbonate selectivity (>99%) and, if two oxirane monomers are used, random incorporation into the polymer feed. The resulting diblock mPEG-b-PGC polymer shows promise as a nanocarrier for surfactant-free, sustained chemotherapeutic delivery. mPEG-b-PGC, with paclitaxel conjugated to the pendant primary alcohol of the glycerol polymer backbone, readily forms 175 nm diameter particles in solution and contains 4.6 wt % paclitaxel (PTX), which is released over 42 days. The mPEG-b-PGC polymer itself is noncytotoxic, whereas the PTX-loaded nanoparticles are cytotoxic to lung, breast, and ovarian cancer cell lines.

Doxorubicin-Loaded Polymeric Meshes Prevent Local Recurrence after Sarcoma Resection While Avoiding Cardiotoxicity

Surgery is the only potentially curative treatment for localized soft-tissue sarcomas. However, for sarcomas arising in the retroperitoneum, locoregional recurrence rates are 35% to 59% despite resection. Doxorubicin (DOX) is the standard first-line systemic chemotherapy for advanced soft-tissue sarcoma, yet its intravenous administration yields limited clinical efficacy and results in dose-limiting cardiotoxicity. We report the fabrication and optimization of a novel electrospun poly(caprolactone) (PCL) surgical mesh coated with layers of a hydrophobic polymer (poly(glycerol monostearate-co-caprolactone), PGC-C18), which delivers DOX directly to the operative bed following sarcoma resection. In xenograft models of liposarcoma and chondrosarcoma, DOX-loaded meshes (DoM) increased overall survival 4-fold compared with systemically administered DOX and prevented local recurrence in all but one animal. Importantly, mice implanted with DoMs exhibited preserved cardiac function, whereas mice receiving an equivalent dose systemically displayed a 23% decrease from baseline in both cardiac output and ejection fraction 20 days after administration. Collectively, this work demonstrates a feasible therapeutic approach to simultaneously prevent post-surgical tumor recurrence and minimize cardiotoxicity in soft-tissue sarcoma.

SIGNIFICANCE

A proof-of-principle study in animal models shows that a novel local drug delivery approach can prevent tumor recurrence as well as drug-related adverse events following surgical resection of soft-tissue sarcomas.

Implantable Devices for the Treatment of Breast Cancer

Breast cancer is one of the leading causes of death in the female population worldwide. Standard treatments such as chemotherapy show noticeable results. However, along with killing cancer cells, it causes systemic toxicity and apoptosis of the nearby healthy cells, therefore patients must endure side effects during the treatment process. Implantable drug delivery devices that enhance therapeutic efficacy by allowing localized therapy with programmed or controlled drug release can overcome the shortcomings of conventional treatments. An implantable device can be composed of biopolymer materials, nanocomposite materials, or a combination of both. This review summarizes the recent research and current state-of-the art in these types of implantable devices and gives perspective for future directions.

Enhanced Paclitaxel Efficacy to Suppress Triple-Negative Breast Cancer Progression Using Metronomic Chemotherapy with a Controlled Release System of Electrospun Poly-d-l-Lactide-Co-Glycolide (PLGA) Nanofibers

Simple Summary

Treatment of metastatic triple-negative breast cancer (TNBC) relies on chemotherapy. To improve the efficacy of chemotherapy and avoid systemic toxicity, metronomic chemotherapy using continuous administration of low-dose chemotherapy could be a solution. The paclitaxel-loaded PLGA nanofibers allow for continuous and prolonged drug release, which is compatible with the concept of metronomic chemotherapy. The animal study revealed that the strategy successfully inhibited the growth of the primary tumor and distant metastasis without sarcopenia. These data offer new insights into the role of drug-loaded nanofibers in the treatment of metastatic TNBC.

Abstract

Triple-negative breast cancer (TNBC) is highly aggressive and responds poorly to conventional chemotherapy. The challenge of TNBC therapy is to maximize the efficacies of conventional chemotherapeutic agents and reduce their toxicities. Metronomic chemotherapy using continuous low-dose chemotherapy has been proposed as a new treatment option, but this approach is limited by the selection of drugs. To improve antitumor therapeutic effects, we developed electrospun paclitaxel-loaded poly-d-l-lactide-co-glycolide (PLGA) nanofibers as a topical implantable delivery device for controlled drug release and site-specific treatment. The subcutaneously implanted paclitaxel-loaded nanofibrous membrane in mice was compatible with the concept of metronomic chemotherapy; it significantly enhanced antitumor activity, inhibited local tumor growth, constrained distant metastasis, and prolonged survival compared with intraperitoneal paclitaxel injection. Furthermore, under paclitaxel-loaded nanofiber treatment, systemic toxicity was low with a persistent increase in lean body weight in mice; in contrast, body weight decreased in other groups. The paclitaxel-loaded nanofibrous membranes provided sustained drug release and site-specific treatment by directly targeting and changing the tumor microenvironment, resulting in low systemic toxicity and a significant improvement in the therapeutic effect and safety compared with conventional chemotherapy. Thus, metronomic chemotherapy with paclitaxel-loaded nanofibrous membranes offers a promising strategy for the treatment of TNBC.

Electrospun paclitaxel delivery system based on PGCL/PLGA in local therapy combined with brachytherapy

The local administration of different drugs in anticancer therapy continue to attract attention. Thus, the idea of local delivery of cytostatics from nonwoven-structured polyesters seems to be highly desirable. It could reduce systemic drug levels and provide high local concentration of the chemotherapeutics at the tumor site and contribute to enhance the efficiency of the anticancer therapy. Poly(glycolide-ɛ-caprolactone) (PGCL) and poly(D,L-lactide-co-glycolide) (PLGA) synthesized with zirconium-based initiator have been used to prepare electrospun, drug-eluting patches since they possess very good fiber-forming ability. Well-known chemotherapeutic drug-paclitaxel has been loaded into fibrous structure as a model anticancer agent in order to obtain drug delivery systems for local administration. The drug dose in obtained nonwovens might be regulated by the thickness and total area of the implanted patches. Electrospinning of PGCL/PLGA blend allowed to obtain soft and flexible implantable materials. Flexibility has been important factor since it ensures convenient use when covering a tumor or filling a resection cavity. The effectiveness of designed nonwovens presented in the study has been tested in vivo on mouse model of breast cancer. The growth of the tumors was slowed down during in vivo study in comparison with drug-free nonwovens- The volume of the tumor was 40% lower. Drug-loaded electrospun systems implanted locally to the tumor site was further combined with brachytherapy which improved the effectiveness of the therapy in about 18%. Detailed analysis of the nonwovens before and during degradation process has been performed by means of Scanning Electron Microscopy, Differential Scanning Calorimetry, Nuclear Magnetic Resonance, Gel Permeation Chromatography, X-ray Diffraction. The molar mass changes of the nonwoven were quite rapid contrary to changes of comonomer unit content, thermal properties and morphology of the fiber.

Delivery of eupenifeldin via polymer-coated surgical buttresses prevents local lung cancer recurrence

Lung cancer is the leading cause of cancer deaths worldwide. Unfortunately, high recurrence rates and poor survival remain despite surgical resection and conventional chemotherapy. Local drug delivery systems are a promising intervention for lung cancer treatment with the potential for improved efficacy with reduced systemic toxicity. Here, we describe the development of a chemotherapy-loaded polymer buttress, to be implanted along the surgical margin at the time of tumor resection, for achieving local and prolonged release of a new anticancer agent, eupenifeldin. We prepared five different formulations of buttresses with varying amounts of eupenifeldin, and additional external empty polymer coating layers (or thicknesses) to modulate drug release. The in vitro eupenifeldin release profile depends on the number of external coating layers with the formulation of the greatest thickness demonstrating a prolonged release approaching 90 days. Similarly, the long-term cytotoxicity of eupenifeldin-loaded buttress formulations against murine Lewis lung carcinoma (LLC) and human lung carcinoma (A549) cell lines mirrors the eupenifeldin release profiles and shows a prolonged cytotoxic effect. Eupenifeldin-loaded buttresses significantly decrease local tumor recurrence in vivo and increase disease-free survival in a lung cancer resection model.

Postoperative cancer treatments: In-situ delivery system designed on demand

The keys to the prevention of tumor recurrence after operation are the elimination of residual tumor cells and the reversal of microenvironments that induce recurrence. In the formulation of a treatment scheme, building an appropriate drug delivery system is essential. An in-situ drug delivery system (ISDDS) is regarded as an effective treatment route for postoperative use that increases drug delivery efficiency and mitigates side-effects. ISDDS technology has been considerably improved through a clearer understanding of the mechanisms of postoperative recurrence and the development of drug delivery materials. This paper describes the initiation and characteristics of postoperative recurrence mechanisms. Based on this information, design principles for ISDDS are proposed, and a variety of practical drug delivery systems that fulfil specific therapeutic needs are presented. Challenges and future opportunities related to the application of in-situ drug carriers for inhibiting cancer recurrence are also discussed.

Preparation, characterization and antitumor activity of a cationic starch-derivative membrane embedded with a β-cyclodextrin/curcumin inclusion complex

A membrane of cationic starch-derivative/poly(vinyl alcohol) was prepared and utilized as a support to immobilize a β-cyclodextrin/curcumin inclusion complex. The resulting material (denote as β-CD/CUR-MBN) was characterized in detail by different techniques. In vitro experiments revealed that β-CD/CUR-MBN enables the controlling of the curcumin release process, which is guided by the relaxation of the polymer matrix. Moreover, cytotoxic assays were performed to investigate the effect of β-CD/CUR-MBN on two cancer cell lines (melanoma and glioblastoma). The results showed that the polymeric membrane exerts higher cytotoxicity against these cells than free curcumin. Also, β-CD/CUR-MBN exerted a prolonged cytotoxic effect (up to 96 h), even using a low concentration (50 μg mL^-1), indicating that the curcumin in the polymeric membrane showed increased bioavailability under the tested condition. β-CD/CUR-MBN was non-cytotoxic against normal cells suggesting a specific action of this material against target cancer cells. The results reported here allow ranks β-CD/CUR-MBN as a promising biomaterial to act as a local drug delivery system to treat cancer.

Polyglycerol Hyperbranched Polyesters: Synthesis, Properties and Pharmaceutical and Biomedical Applications

In a century when environmental pollution is a major issue, polymers issued from bio-based monomers have gained important interest, as they are expected to be environment-friendly, and biocompatible, with non-toxic degradation products. In parallel, hyperbranched polymers have emerged as an easily accessible alternative to dendrimers with numerous potential applications. Glycerol (Gly) is a natural, low-cost, trifunctional monomer, with a production expected to grow significantly, and thus an excellent candidate for the synthesis of hyperbranched polyesters for pharmaceutical and biomedical applications. In the present article, we review the synthesis, properties, and applications of glycerol polyesters of aliphatic dicarboxylic acids (from succinic to sebacic acids) as well as the copolymers of glycerol or hyperbranched polyglycerol with poly(lactic acid) and poly(ε-caprolactone). Emphasis was given to summarize the synthetic procedures (monomer molar ratio, used catalysts, temperatures, etc.,) and their effect on the molecular weight, solubility, and thermal and mechanical properties of the prepared hyperbranched polymers. Their applications in pharmaceutical technology as drug carries and in biomedical applications focusing on regenerative medicine are highlighted.

Local Cancer Recurrence: The Realities, Challenges, and Opportunities for New Therapies

Locoregional recurrence negatively impacts both long-term survival and quality of life for several malignancies. For appropriate-risk patients with an isolated, resectable, local recurrence, surgery represents the only potentially curative therapy. However, oncologic outcomes remain inferior for patients with locally recurrent disease even after macroscopically complete resection. Unfortunately, these operations are often extensive, with significant perioperative morbidity and mortality. This review highlights selected malignancies (mesothelioma, sarcoma, lung cancer, breast cancer, rectal cancer, and peritoneal surface malignancies) in which surgical resection is a key treatment modality and local recurrence plays a significant role in overall oncologic outcome with regard to survival and quality of life. For each type of cancer, the current, state-of-the-art treatment strategies and their outcomes are assessed. The need for additional therapeutic options is presented given the limitations of the current standard therapies. New and emerging treatment modalities, including polymer films and nanoparticles, are highlighted as potential future solutions for both prevention and treatment of locally recurrent cancers. Finally, the authors identify additional clinical and research opportunities and propose future research strategies based on the various patterns of local recurrence among the different cancers.

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.

Tissue Compatibility of SN-38-Loaded Anticancer Nanofiber Matrices

Delivery of chemotherapy in the surgical bed has shown preclinical activity to control cancer progression upon subtotal resection of pediatric solid tumors, but whether this new treatment is safe for tumor-adjacent healthy tissues remains unknown. Here, Wistar rats are used to study the anatomic and functional impact of electrospun nanofiber matrices eluting SN-38-a potent chemotherapeutic agent-on several body sites where pediatric tumors such as neuroblastoma, Ewing sarcoma, and rhabdomyosarcoma arise. Blank and SN-38-loaded matrices embracing the femoral neurovascular bundle or in direct contact with abdominal viscera (liver, kidney, urinary bladder, intestine, and uterus) are placed. Foreign body tissue reaction to the implants is observed though no histologic damage in any tissue/organ. Skin healing is normal. Tissue reaction is similar for SN-38-loaded and blank matrices, with the exception of the hepatic capsule that is thicker for the former although within the limits consistent with mild foreign body reaction. Tissue and organ function is completely conserved after local treatments, as assessed by the rotarod test (forelimb function), hematologic tests (liver and renal function), and control of clinical signs. Overall, these findings support the clinical translation of SN-38-loaded nanofiber matrices to improve local control strategies of surgically resected tumors.

Progress and challenges towards targeted delivery of cancer therapeutics

Targeted delivery approaches for cancer therapeutics have shown a steep rise over the past few decades. However, compared to the plethora of successful pre-clinical studies, only 15 passively targeted nanocarriers (NCs) have been approved for clinical use and none of the actively targeted NCs have advanced past clinical trials. Herein, we review the principles behind targeted delivery approaches to determine potential reasons for their limited clinical translation and success. We propose criteria and considerations that must be taken into account for the development of novel actively targeted NCs. We also highlight the possible directions for the development of successful tumor targeting strategies.

Targeted delivery strategies based on nanocarriers have immense potential to change cancer care but current strategies have been shown only limited translation in the clinic. Here, the authors survey the challenge, progress and opportunities towards targeted delivery of cancer therapeutics.

Enhanced cell uptake of fluorescent drug-loaded nanoparticles via an implantable photothermal fibrous patch for more effective cancer cell killing

Great efforts have been devoted to effective delivery of therapeutics into cells for cancer therapy. The exploration of nanoparticle based drug delivery systems (DDSs) faces daunting challenges in low efficacy of intracellular delivery. Herein, a localized drug delivery device consisting of photoluminescent mesoporous silica nanoparticles (PLMSNs) and photothermal fibrous matrix was investigated. Specifically, PLMSNs modified with a pH-sensitive polydopamine (PDA) 'gatekeeper' served as a doxorubicin (DOX) carrier and could release DOX once the PLMSNs were up-taken by the cancer cells. The PLMSNs were electrostatically assembled on the surface of electrospun biodegradable poly(ε-caprolactone)/gelatin fibrous mesh incorporated with photothermal carbon nanoparticles (CNPs), leading to an implantable patch used as localized delivery platform. Comparing to free particulate DDSs, this implantable composite patch device was found to significantly enable superior cell up-taking effect and consequently enhance in-vitro therapeutic efficacy against tumor cells. Namely, under near infrared irradiation, the photothermal effect of CNPs in the implantable patch weakens the electrostatic interaction between the PLMSNs and poly(ε-caprolactone)/gelatin/CNP fibrous mesh, resulting in the controlled release of the PLMSNs and subsequent internalization into the tumor cells for more effective cancer cell killing. This implantable therapeutic device may therefore inspire another way of developing localized cancer therapy.

Therapeutic strategies for locally recurrent and metastatic de-differentiated liposarcoma with herpes simplex virus-thymidine kinase-expressing mesenchymal stromal cells

BACKGROUND AIMS

Major challenges in de-differentiated liposarcoma (DDLPS) therapy are the high rate of sequential recurrence (>80%) and metastasis (20-30%) following surgical removal. However, well-defined therapeutic strategies for this rare malignancy are lacking and are critically needed.

METHODS

We investigated a new approach to DDLPS therapy with mesenchymal stromal cells expressing herpes simplex virus-thymidine kinase (MSC-TK). In an effort to evaluate this efficacy, in vitro cytotoxicity of MSC-TK against DDLPS cells was analyzed using an apoptosis assay. For pre-clinical study, the MSC-TK-induced reduction in recurrence and metastasis was validated in a recurrent DDLPS model after the macroscopic complete resection and lung metastasis DDLPS model.

RESULTS

MSC-TK induced apoptosis in DDLPS cells by bystander effects via gap junction intracellular communication (GJIC) of toxic ganciclovir (GCV). Recurrent DDLPS models following no residual tumor/microscopic tumor resection and lung metastasis DDLPS models were established, which suggested clinical relevance. MSC-TK markedly reduced locoregional recurrence rates and prolonged recurrence-free survival, thus increasing overall survival in the recurrent DDLPS model. MSC-TK followed by GCV treatment yielded a statistically significant reduction in early- and advanced-stage lung metastasis.

DISCUSSION

This therapeutic strategy may serve as an alternative or additional strategy by applying MSC-TK to target residual tumors following surgical resection, thus reducing local relapse and metastasis in these patients.

Biomaterial-Based Implantable Devices for Cancer Therapy

This review article focuses on the current local therapies mediated by implanted macroscaled biomaterials available or proposed for fighting cancer and also highlights the upcoming research in this field. Several authoritative review articles have collected and discussed the state-of-the-art as well as the advancements in using biomaterial-based micro- and nano-particle systems for drug delivery in cancer therapy. On the other hand, implantable biomaterial devices are emerging as highly versatile therapeutic platforms, which deserve an increased attention by the healthcare scientific community, as they are able to offer innovative, more effective and creative strategies against tumors. This review summarizes the current approaches which exploit biomaterial-based devices as implantable tools for locally administrating drugs and describes their specific medical applications, which mainly target resected brain tumors or brain metastases for the inaccessibility of conventional chemotherapies. Moreover, a special focus in this review is given to innovative approaches, such as combined delivery therapies, as well as to alternative approaches, such as scaffolds for gene therapy, cancer immunotherapy and metastatic cell capture, the later as promising future trends in implantable biomaterials for cancer applications.

Increased survival rate by local release of diclofenac in a murine model of recurrent oral carcinoma

Despite aggressive treatment with radiation and combination chemotherapy following tumor resection, the 5-year survival rate for patients with head and neck cancer is at best only 50%. In this study, we examined the therapeutic potential of localized release of diclofenac from electrospun nanofibers generated from poly(D,L-lactide-co-glycolide) polymer. Diclofenac was chosen since anti-inflammatory agents that inhibit cyclooxygenase have shown great potential in their ability to directly inhibit tumor growth as well as suppress inflammation-mediated tumor growth. A mouse resection model of oral carcinoma was developed by establishing tumor growth in the oral cavity by ultrasound-guided injection of 1 million SCC-9 cells in the floor of the mouth. Following resection, mice were allocated into four groups with the following treatment: 1) no treatment, 2) implanted scaffolds without diclofenac, 3) implanted scaffolds loaded with diclofenac, and 4) diclofenac given orally. Small animal ultrasound and magnetic resonance imaging were utilized for longitudinal determination of tumor recurrence. At the end of 7 weeks following tumor resection, 33% of mice with diclofenac-loaded scaffolds had a recurrent tumor, in comparison to 90%–100% of the mice in the other three groups. At this time point, mice with diclofenac-releasing scaffolds showed 89% survival rate, while the other groups showed survival rates of 10%–25%. Immunohistochemical staining of recurrent tumors revealed a near 10-fold decrease in the proliferation marker Ki-67 in the tumors derived from mice with diclofenac-releasing scaffolds. In summary, the local application of diclofenac in an orthotopic mouse tumor resection model of oral cancer reduced tumor recurrence with significant improvement in survival over a 7-week study period following tumor resection. Local drug release of anti-inflammatory agents should be investigated as a therapeutic option in the prevention of tumor recurrence in oral squamous carcinoma.

Vaginal delivery of carboplatin-loaded thermosensitive hydrogel to prevent local cervical cancer recurrence in mice

Local tumor recurrence after cervical cancer surgery remains a clinical problem. Vaginal delivery of thermosensitive hydrogel may be suited to reduce tumor relapse rate with more efficacy and safety. A pilot study was carried out to evaluate the efficacy of carboplatin-loaded poloxamer hydrogel to prevent local recurrence of cervical cancer after surgery. In vivo vaginal retention evaluation of 27% poloxamer hydrogel in mice was proven to be a suitable vaginal drug delivery formulation due to its low gelation temperature. A mimic orthotopic cervical/vaginal cancer recurrence model after surgery was established by injecting murine cervical cancer cell line U14 into the vaginal submucosa to simulate the residual tumor cells infiltrated in the surgical site, followed by drug administration 24 h later to interfere with the formation/recurrence of the tumor. By infusing fluorescein sodium-loaded hydrogel into the vagina of mice, a maximized accumulation of fluorescein sodium (Flu) in the vagina was achieved and few signals were observed in other organs. When used in the prevention of the cervical cancer formation/recurrence in mice, the carboplatin-loaded poloxamer hydrogel exhibited great efficacy and systemic safety. In conclusion, thermosensitive hydrogel presents a simple, practical approach for the local drug delivery via vagina against cervical cancer recurrence.

Synthetic Biomaterials from Metabolically Derived Synthons

The utility of metabolic synthons as the building blocks for new biomaterials is based on the early application and success of hydroxy acid based polyesters as degradable sutures and controlled drug delivery matrices. The sheer number of potential monomers derived from the metabolome (e.g., lactic acid, dihydroxyacetone, glycerol, fumarate) gives rise to almost limitless biomaterial structural possibilities, functionality, and performance characteristics, as well as opportunities for the synthesis of new polymers. This review describes recent advances in new chemistries, as well as the inventive use of traditional chemistries, toward the design and synthesis of new polymers. Specific polymeric biomaterials can be prepared for use in varied medical applications (e.g., drug delivery, tissue engineering, wound repair, etc.) through judicious selection of the monomer and backbone linkage.

Preparation and therapeutic application of docetaxel-loaded poly(d,l-lactide) nanofibers in preventing breast cancer recurrence

The aim of this study was to develop docetaxel (DTX)-loaded poly-d,l-lactide (PDLLA) nanofibers and evaluate their therapeutic effect in preventing local breast cancer recurrence. DTX was incorporated into biodegradable PDLLA nanofibers by electrospinning. The surface morphology of the DTX/PDLLA nanofibers was characterized using scanning electron microscopy and wide angle X-ray diffraction. The in vitro release behavior of DTX from the fiber mats was also studied in detail. The cytotoxicity of DTX/PDLLA nanofibers was evaluated by MTT assay in 4T1 breast cancer cells. Flow cytometry revealed that DTX/PDLLA nanofibers exhibited apoptotic activity in 4T1 cells. In vivo antitumor efficacy of DTX/PDLLA nanofibers was evaluated in BALB/c mice bearing local breast tumors. Locoregional recurrence after primary tumor resection decreased obviously in mice treated with subcutaneously (16.7%) administered DTX-loaded PDLLA nanofibers, compared with the blank PDLLA nanofibers (88.9%), systemic (75.0%) or locally (77.8%) administered DTX and the control group (100%) (p < 0.05). Finally, after subcutaneous transplantation in mice, the DTX/PDLLA scaffolds presented excellent biocompatibility, as exhibited by the minimal presence of inflammatory cells in the region surrounding the scaffolds. Our results suggest that DTX/PDLLA nanofibers could have great potential for clinical application requiring local chemotherapy.

A tissue-engineered therapeutic device inhibits tumor growth in vitro and in vivo

Bone metastasis is one of the leading causes of death in breast cancer patients. The current treatment is performed as a palliative therapy and the adverse side effects can compromise the patients' quality of life. In order to both effectively treat bone metastasis and avoid the limitation of current strategies, we have invented a drug eluting scaffold with clay matrix release doxorubicin (DESCLAYMR_DOX) to mechanically support the structure after resecting the metastatic tissue while also releasing the anticancer drug doxorubicin which supplements growth inhibition and elimination of the remaining tumor cells. We have previously demonstrated that this device has the capacity to regenerate the bone and provide sustained release of the anticancer drug in vitro. In this study, we focus on the ability of the device to inhibit cancer cell growth in vitro as well as in vivo. Drug-release kinetics was investigated and the cell viability test showed that the tumor inhibitory effect is sustained for up to 4weeks in vitro. Subcutaneous implantation of DESCLAYMR_DOX in athymic mice resulted in significant growth inhibition of human tumor xenografts of breast origin and decelerated multi-organ metastasis formation. Fluorescence images, visualizing doxorubicin, showed a sustained drug release from the DESCLAYMR device in vivo. Furthermore, local use of DESCLAYMR_DOX implantation reduced the incidence of doxorubicin's cardio-toxicity. These results suggest that DESCLAYMR_DOX can be used in reconstructive surgery to support the structure after bone tumor resection and facilitate a sustained release of anticancer drugs in order to prevent tumor recurrence.

Molecular mechanism of local drug delivery with Paclitaxel-eluting membranes in biliary and pancreatic cancer: new application for an old drug

Implantation of self-expanding metal stents (SEMS) is palliation for patients suffering from inoperable malignant obstructions associated with biliary and pancreatic cancers. Chemotherapeutic agent-eluting stents have been developed because SEMS are susceptible to occlusion by tumor in-growth. We reported recently that paclitaxel-eluting SEMS provide enhanced local drug delivery in an animal model. However, little is known about the molecular mechanisms by which paclitaxel-eluting stents attenuate tumor growth. We investigated the signal transduction pathways underlying the antiproliferative effects of a paclitaxel-eluting membrane (PEM) implanted in pancreatic/cholangiocarcinoma tumor bearing nude mice. Molecular and cellular alterations were analyzed in the PEM-implanted pancreatic/cholangiocarcinoma xenograft tumors by Western blot, immunoprecipitation, and immunofluorescence. The quantities of paclitaxel released into the tumor and plasma were determined by liquid chromatography-tandem mass spectroscopy. Paclitaxel from the PEM and its diffusion into the tumor inhibited angiogenesis, which involved suppression of mammalian target of rapamycin (mTOR) through regulation of hypoxia inducible factor (HIF-1) and increased apoptosis. Moreover, implantation of the PEM inhibited tumor-stromal interaction-related expression of proteins such as CD44, SPARC, matrix metalloproteinase-2, and vimentin. Local delivery of paclitaxel from a PEM inhibited growth of pancreatic/cholangiocarcinoma tumors in nude mice by suppressing angiogenesis via the mTOR and inducing apoptosis signal pathway.

Recent advances in glycerol polymers: chemistry and biomedical applications

Glycerol polymers are attracting increased attention due to the diversity of polymer compositions and architectures available. This article provides a brief chronological review on the current status of these polymers along with representative examples of their use for biomedical applications. First, the underlying chemistry of glycerol that provides access to a range of monomers for subsequent polymerizations is described. Then, the various synthetic methodologies to prepare glycerol-based polymers including polyethers, polycarbonates, polyesters, and so forth are reviewed. Next, several biomedical applications where glycerol polymers are being investigated including carriers for drug delivery, sealants or coatings for tissue repair, and agents possessing antibacterial activity are described. Fourth, the growing market opportunity for the use of polymers in medicine is described. Finally, the findings are concluded and summarized, as well as the potential opportunities for continued research efforts are discussed.

Triggered drug release from superhydrophobic meshes using high-intensity focused ultrasound

Application of high-intensity focused ultrasound to drug-loaded superhydrophobic meshes affords triggered drug release by displacing an entrapped air layer. The air layer within the superhydrophobic meshes is characterized using direct visualization and B-mode imaging. Drug-loaded superhydrophobic meshes are cytotoxic in an in vitro assay after ultrasound treatment.

Current advances in animal model of chondrosarcoma and related research

Chondrosarcoma is a type of malignant cartilage tumor with a high local recurrence. Due to its resistance to chemo- and radiotherapy, current treatment is limited to surgical resection. Animal model is one of the most important approaches to studying this disease, although systematic reporting on its development is rare. In this review, we summarized the elements involving animal model establishment. On the basis of these elements, we further classified chondrosarcoma animal models into various types. In addition, we compared various measurements for evaluating the animal model. Finally, its specific applications were discussed.

Therapeutic application of injectable thermosensitive hydrogel in preventing local breast cancer recurrence and improving incision wound healing in a mouse model

Many drug delivery systems (DDSs) have been investigated for local targeting of malignant disease with the intention of increasing anti-tumor activity and minimizing systemic toxicity. An injectable thermosensitive hydrogel was applied to prevent locoregional recurrence of 4T1 breast cancer in a mouse model. The presented hydrogel, which is based on poly(ethyleneglycol)-poly(ε-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG, PECE), flows freely at normal temperature, forms a gel within seconds in situ at body temperature, and eventually releases the drug in a consistent and sustained fashion as it gradually biodegrades. Locoregional recurrence after primary tumor removal was significantly inhibited in mice treated with the paclitaxel (PTX)-loaded PECE hydrogel subcutaneously (9.1%) administered, compared with the blank hydrogel (80.0%), systemic (77.8%) and locally (75.0%) administered PTX, and the control group (100%) (P < 0.01). In addition, tensile strength measurements of the surgical incisions showed that the PECE hydrogel accelerates wound healing at postoperative day 7 (P < 0.05), and days 4 and 14 (P > 0.05), in agreement with histopathological examinations. This novel DDSs represents a promising approach for local adjuvant therapy in malignant disease.

Physical confinement alters tumor cell adhesion and migration phenotypes

Cell migration on planar surfaces is driven by cycles of actin protrusion, integrin-mediated adhesion, and myosin-mediated contraction; however, this mechanism may not accurately describe movement in 3-dimensional (3D) space. By subjecting cells to restrictive 3D environments, we demonstrate that physical confinement constitutes a biophysical stimulus that alters cell morphology and suppresses mesenchymal motility in human breast carcinoma (MDA-MB-231). Dorsoventral polarity, stress fibers, and focal adhesions are markedly attenuated by confinement. Inhibitors of myosin, Rho/ROCK, or β1-integrins do not impair migration through 3-μm-wide channels (confinement), even though these treatments repress motility in 50-μm-wide channels (unconfined migration) by ≥50%. Strikingly, confined migration persists even when F-actin is disrupted, but depends largely on microtubule (MT) dynamics. Interfering with MT polymerization/depolymerization causes confined cells to undergo frequent directional changes, thereby reducing the average net displacement by ≥80% relative to vehicle controls. Live-cell EB1-GFP imaging reveals that confinement redirects MT polymerization toward the leading edge, where MTs continuously impact during advancement of the cell front. These results demonstrate that physical confinement can induce cytoskeletal alterations that reduce the dependence of migrating cells on adhesion-contraction force coupling. This mechanism may explain why integrins can exhibit reduced or altered function during migration in 3D environments.

3D superhydrophobic electrospun meshes as reinforcement materials for sustained local drug delivery against colorectal cancer cells

In this work we expand upon a recently reported local drug delivery device, where air is used as a degradable component of our material to control drug release (J. Am. Chem. Soc. 2012, 134, 2016-2019). We consider its potential use as a drug loaded strip to provide both mechanical stability to the anastomosis, and as a means to release drug locally over prolonged periods for prevention of locoregional recurrence in colorectal cancer. Specifically, we electrospun poly(ε-caprolactone) (PCL) with the hydrophobic polymer dopant poly(glycerol monostearate-co-ε-caprolactone) (PGC-C18) and used the resultant mesh to control the release of two anticancer drugs (CPT-11 and SN-38). The increase in mesh hydrophobicity with PGC-C18 addition slows drug release both by the traditional means of drug diffusion, as well as by increasing the stability of the entrapped air layer to delay drug release. We demonstrate that superhydrophobic meshes have mechanical properties appropriate for surgical buttressing of the anastomosis, permit non-invasive assessment of mesh location and documentation of drug release via ultrasound, and release chemotherapy over a prolonged period of time (>90 days) resulting in significant tumor cytotoxicity against a human colorectal cell line (HT-29).

Functionalized hydrophobic poly(glycerol-co-ε-caprolactone) depots for controlled drug release

A limitation to many polymer-based drug delivery systems is the lack of ability to customize a particular polymer composition for tailoring drug release kinetics to a specific clinical application. In this study, we investigated the structure-property effects of conjugating various hydrophobic biocompatible side chains to poly(glycerol-co-caprolactone) copolymers with the goal of achieving prolonged and controlled release of a chemotherapeutic agent. The choice of side chain significantly affected the resulting polymer properties including thermal transitions, relative crystallinity (ΔH(f)), and hydrophobicity. Drug-loaded films cast from solutions of polymer and 10-hydroxycamptothecin demonstrated prolonged release from four to over seven weeks depending upon side chain structure without initial burst release behavior. Use of the stearic acid-conjugated poly(glycerol-co-caprolactone) films afforded substantial anticancer activity in vitro for at least 50 days when exposed to fresh cultures of A549 human lung cancer cells over 24 h intervals, correlating well with the measured drug release kinetics.

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.