Intratumoral delivery of Paclitaxel in solid tumor from biodegradable hyaluronan nanoparticle formulations

Locoregional drug delivery for cancer therapy: Preclinical progress and clinical translation

Systemic drug delivery is the current clinically preferred route for cancer therapy. However, challenges associated with tumor localization and off-tumor toxic effects limit the clinical effectiveness of this route. Locoregional drug delivery is an emerging viable alternative to systemic therapies. With the improvement in real-time imaging technologies and tools for direct access to tumor lesions, the clinical applicability of locoregional drug delivery is becoming more prominent. Theoretically, locoregional treatments can bypass challenges faced by systemic drug delivery. Preclinically, locoregional delivery of drugs has demonstrated enhanced therapeutic efficacy with limited off-target effects while still yielding an abscopal effect. Clinically, an array of locoregional strategies is under investigation for the delivery of drugs ranging in target and size. Locoregional tumor treatment strategies can be classified into two main categories: 1) direct drug infusion via injection or implanted port and 2) extended drug elution via injected or implanted depot. The number of studies investigating locoregional drug delivery strategies for cancer treatment is rising exponentially, in both preclinical and clinical settings, with some approaches approved for clinical use. Here, we highlight key preclinical advances and the clinical relevance of such locoregional delivery strategies in the treatment of cancer. Furthermore, we critically analyze 949 clinical trials involving locoregional drug delivery and discuss emerging trends.

Transpapillary iontophoretic delivery of resveratrol loaded transfersomes for localized delivery to breast cancer

Localized drug delivery to the breast tissues is an area of interest as a potential route to ensure site-specific drug delivery. Transpapillary delivery via the mammary papilla has advantages as most breast tumors arise from the milk ducts. The present study explored the plausibility of transpapillary delivery of a phytochemical, resveratrol (RVT), for breast cancer treatment. RVT was encapsulated within the transfersomes (RVT-TRF) to enable a sustained release of the drug using the biomaterial soya phosphatidylcholine (SPC). Iontophoresis was applied to further accelerate the penetration of the RVT-TRF across the mammary papilla to the breast tissue. The RVT-TRF development was optimized by the Design of Experiments (DoE) approach. The in vitro transpapillary iontophoresis study on porcine mammary papilla showed an enhanced penetration of RVT-TRF when compared to passive diffusion. The transpapillary delivery was further confirmed from the in vitro fluorescent microscopy study using FITC conjugated RVT-TRF. The optimized RVT-TRF delivered via transpapillary route showed a higher C_max and AUC when compared to pure RVT given orally. A significant reduction in the tumor volume and the serum biomarker CA 15-3, when evaluated in a chemically induced breast cancer rat model, provided evidence of the effectiveness of the developed formulation when delivered locally via transpapillary route compared to the oral route. Thus the developed RVT-TRF administered via transpapillary iontophoresis technique is a promising strategy enabling a localized delivery for effective breast cancer therapy.

Discovery and Development of the Quininib Series of Ocular Drugs

The quininib series is a novel collection of small-molecule drugs with antiangiogenic, antivascular permeability, anti-inflammatory, and antiproliferative activity. Quininib was initially identified as a drug hit during a random chemical library screen for determinants of developmental ocular angiogenesis in zebrafish. To enhance drug efficacy, novel quininib analogs were designed by applying medicinal chemistry approaches. The resulting quininib drug series has efficacy in in vitro and ex vivo models of angiogenesis utilizing human cell lines and tissues. In vivo, quininib drugs reduce pathological angiogenesis and retinal vascular permeability in rodent models. Quininib acts as a cysteinyl leukotriene (CysLT) receptor antagonist, revealing new roles of these G-protein-coupled receptors in developmental angiogenesis of the eye and unexpectedly in uveal melanoma (UM). The quininib series highlighted the potential of CysLT receptors as therapeutic targets for retinal vasculopathies (e.g., neovascular age-related macular degeneration, diabetic retinopathy, and diabetic macular edema) and ocular cancers (e.g., UM).

Nanoparticle-Assisted Diagnosis and Treatment for Abdominal Aortic Aneurysm

An abdominal aortic aneurysm (AAA) is a localized dilatation of the aorta related to the regional weakening of the wall structure, resulting in substantial morbidity and mortality with the aortic ruptures as complications. Ruptured AAA is a dramatic catastrophe, and aortic emergencies constitute one of the leading causes of acute death in older adults. AAA management has been centered on surgical repair of larger aneurysms to mitigate the risks of rupture, and curative early diagnosis and effective pharmacological treatments for this condition are still lacking. Nanoscience provided a possibility of more targeted imaging and drug delivery system. Multifunctional nanoparticles (NPs) may be modified with ligands or biomembranes to target agents' delivery to the lesion site, thus reducing systemic toxicity. Furthermore, NPs can improve drug solubility, circulation time, bioavailability, and efficacy after systemic administration. The varied judiciously engineered nano-biomaterials can exist stably in the blood vessels for a long time without being taken up by cells. Here, in this review, we focused on the NP application in the imaging and treatment of AAA. We hope to make an overview of NP-assisted diagnoses and therapy in AAA and discussed the potential of NP-assisted treatment.

Strategies for Delivering Nanoparticles across Tumor Blood Vessels

Nanoparticle transport across tumor blood vessels is a key step in nanoparticle delivery to solid tumors. However, the specific pathways and mechanisms of this nanoparticle delivery process are not fully understood. Here, the biological and physical characteristics of the tumor vasculature and the tumor microenvironment are explored and how these features affect nanoparticle transport across tumor blood vessels is discussed. The biological and physical methods to deliver nanoparticles into tumors are reviewed and paracellular and transcellular nanoparticle transport pathways are explored. Understanding the underlying pathways and mechanisms of nanoparticle tumor delivery will inform the engineering of safer and more effective nanomedicines for clinical translation.

New PTX-HS15/T80 Mixed Micelles: Cytotoxicity, Pharmacokinetics and Tissue Distribution

Compared with single micelle, the new PTX-HS15/T80 mixed micelle system (PTX-HS15/T80 MMs) had achieved better results in solubilization, stability, and sensitization before. Therefore, we intend to further verify the potential advantages of the mixed micelle delivery system through in vitro cytotoxicity test and animal test to understand the anticancer effect and in vivo pharmaceutical behavior of the system. In vitro cytotoxicity test showed that the new PTX-HS15/T80 MMs had a stronger ability to inhibit the proliferation of cancer cells. The results of in vivo pharmacokinetics showed that the micelle had shorter half-life, higher clearance rate, and lower blood concentration and had good blood clearance characteristics. The results of in vivo tissue distribution showed that, compared with the single micelle Taxol^®, the new PTX-HS15/T80 MMs had good distribution characteristics in the lung (AUC _{(lung 0-4 H)} increased about 26%) and low concentration in the heart (AUC _{(Heart 0-4 H)} decreased about 10%). Paclitaxel was mainly metabolized through the liver and kidney. The above results suggested that the new PTX-HS15/T80 MMs may have a certain therapeutic potential against lung cancer and reduce the toxic and side effects. In general, the mixed micelle delivery system was not only simple and cheap to prepare but also had certain advantages in vitro and in vivo, indicating that the combination of surfactants provides a good choice for solving the problem of insoluble drug delivery.

Recent progress on nanoparticles for targeted aneurysm treatment and imaging

An abdominal aortic aneurysm (AAA) is a localized dilatation of the aorta that plagues millions. Its rupture incurs high mortality rates (~80-90%), pressing an urgent need for therapeutic methods to prevent this deadly outcome. Judiciously designed nanoparticles (NPs) have displayed a unique potential to fulfill this need. Aneurysms feature excessive inflammation and extracellular matrix (ECM) degradation. As such, typically inflammatory cells and exposed ECM proteins have been targeted with NPs for therapeutic, diagnostic, or theranostic purposes in experimental models. NPs have been used not only for encapsulation and delivery of drugs and biomolecules in preclinical tests, but also for enhanced imaging to monitor aneurysm progression in patients. Moreover, they can be readily modified with various molecules to improve lesion targeting, detectability, biocompatibility, and circulation time. This review updates on the progress, limitations, and prospects of NP applications in the context of AAA.

Controlling complexation/decomplexation and sizes of polymer-based electrostatic pDNA polyplexes is one of the key factors in effective transfection

The delivery of plasmid DNA (pDNA) using polycations has been investigated for several decades; however, obstacles that limit efficient gene delivery still hinder the clinical application of gene therapy. One of the major limiting factors is controlling pDNA binding affinity with polymers to control the complexation and decomplexation of polyplexes. To address this challenge, polycations of α-poly(_L-lysine) (APL) and ε-poly(_L-lysine) (EPL) were used to prepare variable complexation/decomplexation polyplexes with binding affinities ranging from too tight to too loose and sizes ranging from small to large. APL-EPL/ATP-pDNA polyplexes were also prepared to compare the effects of endosomolytic ATP on complexation/decomplexation and the sizes of polyplexes. The results showed that smaller and tighter polyplexes delivered more pDNA into the cells and into the nucleus than the larger and looser polyplexes. Larger polyplexes exhibited slower cytosolic transport and consequently less nuclear delivery of pDNA than smaller polyplexes. Tighter polyplexes exhibited poor pDNA release in the nucleus, leading to no improvement in transfection efficiency. Thus, polyplexes should maintain a balance between complexation and decomplexation and should have optimal sizes for effective cellular uptake, cytosolic transport, nuclear import, and gene expression. Understanding the effects of complexation/decomplexation and size is important when designing effective polymer-based electrostatic gene carriers.

Advances in personalized treatment of metastatic spine disease

The spine is one of the most common sites of bony metastases, and its involvement leads to significant patient morbidity. Surgical management in these patients is aimed at improving quality of life and functional status throughout the course of the disease. Resection of metastases often leads to critical size bone defects, presenting a challenge to achieving adequate bone regeneration to fill the void. Current treatment options for repairing these defects are bone grafting and commercial bone cements; however, each has associated limitations. Additionally, tumor recurrence and tumor-induced bone loss make bone regeneration particularly difficult. Systemic therapeutic delivery, such as bisphosphonates, have become standard of care to combat bone loss despite unfavorable systemic side-effects and lack of local efficacy. Developments from tissue engineering have introduced novel materials with osteoinductive and osteoconductive properties which also act as structural support scaffolds for bone regeneration. These new materials can also act as a therapeutic reservoir to sustainably release drugs locally as an alternative to systemic therapy. In this review, we outline recent advancements in tissue engineering and the role of translational research in developing implants that can fully repair bone defects while also delivering local therapeutics to curb tumor recurrence and improve patient quality of life.

Development of a biodegradable antifibrotic local drug delivery system for glaucoma microstents

To prevent implant failure due to fibrosis is a major objective in glaucoma research. The present study investigated the antifibrotic effects of paclitaxel (PTX), caffeic acid phenethyl ester (CAPE), and pirfenidone (PFD) coated microstent test specimens in a rat model. Test specimens based on a biodegradable blend of poly(4-hydroxybutyrate) biopolymer and atactic poly(3-hydroxybutyrate) (at.P(3HB)) were manufactured, equipped with local drug delivery (LDD) coatings, and implanted in the subcutaneous white fat depot. Postoperatively, test specimens were explanted and analyzed for residual drug content. Fat depots including the test specimens were histologically analyzed. In vitro drug release studies revealed an initial burst for LDD devices. In vivo, slow drug release of PTX was found, whereas it already completed 1 week postoperatively for CAPE and PFD LDD devices. Histological examinations revealed a massive cell infiltration in the periphery of the test specimens. Compact fibrotic capsules around the LDD devices were detectable at 4–36 weeks and least pronounced around PFD-coated specimens. Capsules stained positive for extracellular matrix (ECM) components. The presented model offers possibilities to investigate release kinetics and the antifibrotic potential of drugs in vivo as well as the identification of more effective agents for a novel generation of drug-eluting glaucoma microstents.

Therapeutic effect of simvastatin on DMBA-induced breast cancer in mice

Preclinical studies have shown positive effects of statins against specific cancers. This study aimed to determine the therapeutic effect of simvastatin in 12-dimethylbenz(a)anthracene (DMBA)-induced breast cancer. Female albino mice were divided into two groups, with or without DMBA administration. After tumor appearance, DMBA-treated group was further divided into four groups (D1-D4) as control (D1), treated with simvastatin at 80 and 40 mg/kg/day, orally (D2 and D3) and tamoxifen (50 mg/kg/day, orally) treated group (D4). After 4 weeks, animals were sacrificed, serum samples were collected and tumors were dissected for histopathological study and determination of selected parameters. The tumor marker carcinoma antigen 15-3 (CA15-3), oxidative stress parameters and prostaglandin E2 (PGE2) levels were analyzed in serum and tumors in experimental groups. Tamoxifen and high dose of simvastatin improved parameters of mammary carcinogenesis including mean tumor volume, body weight and percent of mortality as compared to mice with breast tumors without treatment (D1). Additionally, simvastatin usage increased total antioxidant capacity (TAC) level, paraoxonase 1 (PON1) activity in serum and decreased total oxidant status (TOS) and malondialdehyde (MDA) levels in tumors similar to tamoxifen. No significant decrease was found in serum CA 15-3 and tumor PGE2 levels in simvastatin and tamoxifen treated groups as compared to D1 group. These data suggest that simvastatin has anticancer effects which are relatively similar to that of tamoxifen in an animal model of breast cancer.

Polysaccharide-Based Controlled Release Systems for Therapeutics Delivery and Tissue Engineering: From Bench to Bedside

Polysaccharides or polymeric carbohydrate molecules are long chains of monosaccharides that are linked by glycosidic bonds. The naturally based structural materials are widely applied in biomedical applications. This article covers four different types of polysaccharides (i.e., alginate, chitosan, hyaluronic acid, and dextran) and emphasizes their chemical modification, preparation approaches, preclinical studies, and clinical translations. Different cargo fabrication techniques are also presented in the third section. Recent progresses in preclinical applications are then discussed, including tissue engineering and treatment of diseases in both therapeutic and monitoring aspects. Finally, clinical translational studies with ongoing clinical trials are summarized and reviewed. The promise of new development in nanotechnology and polysaccharide chemistry helps clinical translation of polysaccharide-based drug delivery systems.

Distribution of Glutathione-Stabilized Gold Nanoparticles in Feline Fibrosarcomas and Their Role as a Drug Delivery System for Doxorubicin-Preclinical Studies in a Murine Model

Feline injection site sarcomas (FISS) are malignant skin tumors with high recurrence rates despite the primary treatment of radical surgical resections. Adjunctive radiotherapy or chemotherapy with doxorubicin is mostly ineffective. Cellular and molecular causes of multidrug resistance, specific physio-chemical properties of solid tumors impairing drug transport, and the tumor microenvironment have been indicated for causing standard chemotherapy failure. Gold nanoparticles are promising imaging tools, nanotherapeutics, and drug delivery systems (DDS) for chemotherapeutics, improving drug transport within solid tumors. This study was conducted to assess the distribution of 4-nm glutathione-stabilized gold nanoparticles in FISS and their influence on kidney and liver parameters in nude mice. The role of gold nanoparticles as a doxorubicin DDS in FISS was examined to determine the potential reasons for failure to translate results from in vitro to in vivo studies. Grade III tumors characterized by a large area of necrosis at their core displayed positive immuneexpression of tumor-associated macrophages (TAM) at both the periphery and within the tumor core near the area of necrosis. Gold nanoparticles did not cause necrosis at the injection site and had no negative effect on liver and kidney parameters in nude mice. Gold nanoparticles accumulated in the tumor core and at the periphery and co-internalized with TAM—an important observation and potential therapeutic target warranting further investigation. The large area of necrosis and high immunoexpression of TAM, indicating “pro-tumor macrophages”, may be responsible for FISS tumor progression and therapeutic failure. However, further studies are required to test this hypothesis.

CD44 targeting hyaluronic acid coated lapatinib nanocrystals foster the efficacy against triple-negative breast cancer

Lapatinib (LPT) is an orally administered drug for the treatment of metastatic breast cancer. For expanding its therapeutic horizon, we have prepared its nanocrystals (LPT-NCs) that were subsequently coated with hyaluronic acid (HA) to produce LPT-HA-NCs. The detailed in-vitro and in-vivo investigation of LPT-HA-NCs showed the superior anticancer activity due to active targeting to CD44 receptors than the counterparts LPT-NCs and free LPT. In the triple negative 4T1 cells induced breast tumor bearing female Balb/C mice; LPT-HA-NCs treatment caused significant retardation of tumor growth and overall increase in animal survival probability because of their higher tumor localization, increased residence time. Our findings clearly suggest that HA coated LPT-NCs formulation enhances the activity of LPT against triple negative breast cancer. It exhibited magnificent therapeutic outcome at low dose thus presenting a strategy to reduce dose administrations and minimize dose related toxicity.

Drug Delivery Strategies for Platinum-Based Chemotherapy

Few chemotherapeutics have had such an impact on cancer management as cis-diamminedichloridoplatinum(II) (CDDP), also known as cisplatin. The first member of the platinum-based drug family, CDDP's potent toxicity in disrupting DNA replication has led to its widespread use in multidrug therapies, with particular benefit in patients with testicular cancers. However, CDDP also produces significant side effects that limit the maximum systemic dose. Various strategies have been developed to address this challenge including encapsulation within micro- or nanocarriers and the use of external stimuli such as ultrasound to promote uptake and release. The aim of this review is to look at these strategies and recent scientific and clinical developments.

Future trends and emerging issues for nanodelivery systems in oral and oropharyngeal cancer

Oral cancer is a prevalent cancer type on a global scale, whose traditional treatment strategies have several drawbacks that could in the near future be overcome through the development of novel therapeutic and prognostic strategies. Nanotechnology provides an alternative to traditional therapy that leads to enhanced efficiency and less toxicity. Various nanosystems have been developed for the treatment of oral cancer, including polymeric, metallic, and lipid-based formulations that incorporate chemotherapeutics, natural compounds, siRNA, or other molecules. This review summarizes the main benefits of using these nanosystems, in parallel with a particular focus on the issues encountered in medical practice. These novel strategies have provided encouraging results in both in vitro and in vivo studies, but few have entered clinical trials. The use of nanosystems in oral cancer has the potential of becoming a valid therapeutic option for patients suffering from this malignancy, considering that clinical trials have already been completed and others are currently being developed.

Targeted delivery of doxorubicin to tumour tissues by a novel legumain sensitive polygonal nanogel

Targeted delivery of cytotoxic drugs to tumour tissue has great importance for successful chemotherapy. Legumain is an asparaginyl endopeptidase that is highly up-regulated in a number of solid tumours. The aim of this work was to prepare a novel hyaluronic acid (HA) based legumain sensitive nanogel for the delivery of doxorubicin with a high targeting efficiency both in vitro and in vivo. The legumain sensitive property is achieved by the conjugation of doxorubicin with HA via a legumain substrate peptide bridge. This HA derivative is further crosslinked in a water/oil solvent system to form a polygonal nanogel. Doxorubicin released in the tumour tissue is sustained thanks to the combined action of legumain and hyaluronidase, which are both overexpressed in tumour tissues. Hyaluronic acid could act as a targeting agent to CD44 (HA receptor), which further improved the in vivo target effect and enhanced in vitro cellular uptake. The developed nanogel exhibited a high therapeutic index that improved tumour inhibition effects and reduced system toxicity in a lung cancer mice model. These results highlighted the advantages of using this multi-functional material for a successful delivery of doxorubicin against cancer.

Intratumoral Photodynamic Therapy With Newly Synthesized Pheophorbide a in Murine Oral Cancer

Photodynamic therapy (PDT) is a therapeutic alternative for malignant tumors that uses a photosensitizer. Our group recently synthesized photosensitizer pheophorbide a (Pa) from chlorophyll-a. The present study investigated the therapeutic effect of PDT using intratumoral administration of the synthetic photosensitizer Pa in an in vivo murine oral squamous cell carcinoma (OSCC) animal model. Pa accumulation was measured using the fluorescence spectrum and imaging in living C3H mice. Intratumoral treatment of Pa-PDT (IT Pa-PDT) significantly inhibited the growth of transplanted OSCC cells. Histopathological examination of tumor tissues showed that PCNA expression was significantly decreased, while TUNEL-stained cells were markedly increased in the IT Pa-PDT group compared to controls. IT Pa-PDT-induced apoptosis was confirmed by immunoblot. Reduction of Bcl-2 and cleavage of caspase 3 and PARP were observed in IT Pa-PDT. These data demonstrate that IT Pa-PDT inhibited tumor cell proliferation and induced apoptosis, which is correlated with the anticancer activity of IT Pa-PDT. These potent antitumor activities of IT Pa-PDT were observed in both the immunohistochemistry and Western blot experiments. Our findings suggest the intratumoral therapeutic potential of Pa-PDT on OSCC. Additionally, demonstrated detection of Pa using a fluorescence spectroscopy system or molecular imaging system provides a means for simultaneous diagnosis and treatment of OSCC.

Nanotechnology: Future of Oncotherapy

Recent advances in nanotechnology have established its importance in several areas including medicine. The myriad of applications in oncology range from detection and diagnosis to drug delivery and treatment. Although nanotechnology has attracted a lot of attention, the practical application of nanotechnology to clinical cancer care is still in its infancy. This review summarizes the role that nanotechnology has played in improving cancer therapy, its potential for affecting all aspects of cancer care, and the challenges that must be overcome to realize its full promise.

Hyaluronic acid for anticancer drug and nucleic acid delivery

Hyaluronic acid (HA) is widely used in anticancer drug delivery, since it is biocompatible, biodegradable, non-toxic, and non-immunogenic; moreover, HA receptors are overexpressed on many tumor cells. Exploiting this ligand-receptor interaction, the use of HA is now a rapidly-growing platform for targeting CD44-overexpressing cells, to improve anticancer therapies. The rationale underlying approaches, chemical strategies, and recent advances in the use of HA to design drug carriers for delivering anticancer agents, are reviewed. Comprehensive descriptions are given of HA-based drug conjugates, particulate carriers (micelles, liposomes, nanoparticles, microparticles), inorganic nanostructures, and hydrogels, with particular emphasis on reports of preclinical/clinical results.

Preparation and characterization of amphiphilic calixarene nanoparticles as delivery carriers for paclitaxel

Two types of amphoteric calix[n]arene carboxylic acid (CnCA) derivative, i.e., calix[6]arene hexa-carboxylic acid (C6HCA) and calix[8]arene octo-carboxylic acid (C8OCA), were synthesized by introducing acetoxyls into the hydroxyls of calix[n]arene (n=6, 8). C6HCA and C8OCA nanoparticles (NPs) were prepared successfully using the dialysis method. CnCA NPs had regular spherical shapes with an average diameter of 180-220 nm and possessed negative charges of greater than -30 mV. C6HCA and C8OCA NPs were stable in 4.5% bovine serum albumin solutions and buffers (pH 5-9), with a low critical aggregation concentration value of 5.7 mg·L(-1) and 4.0 mg·L(-1), respectively. C6HCA and C8OCA NPs exhibited good paclitaxel (PTX) loading capacity, with drug loading contents of 7.5% and 8.3%, respectively. The overall in vitro release behavior of PTX from the CnCA NPs was sustained, and C8OCA NPs had a slower release rate compared with C6HCA NPs. These favorable properties of CnCA NPs make them promising nanocarriers for tumor-targeted drug delivery.

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.

Tagging staphylococcal enterotoxin B (SEB) with TGFaL3 for breast cancer therapy

Recent research has attempted to direct superantigens towards tumors by means of tumor-targeted superantigen (TTS) strategy. In this study, we explored the antitumor property of TTS by fusing the third loop of transforming growth factor α (TGFαL3) to staphylococcal enterotoxin type B (SEB) and investigated the possibility of the therapeutic application of TGFαL3-SEB as a novel antitumor candidate in mice bearing breast cancer. Treatment was performed through intratumoral and intravenous injection of TGFαL3-SEB. Tumor size/volume, long-term survival, and cytokine secretion were assessed. In addition, the toxicity of each treatment on liver and kidneys was examined. Our results indicated that the relative tumor volume significantly increased in the mice receiving intratumoral TGFaL3-SEB (p < 0.05). Surprisingly, 5 out of the 14 mice were cleared from the tumor thoroughly in 10-25 days after intratumoral administration of TGFaL3-SEB. Quantification of cytokines clearly showed that the mice receiving intratumoral SEB significantly secreted higher interferon γ (IFN-γ) and tumor necrosis factor α (TNF-α) compared with the other groups (p < 0.05). The antitumor effect was followed by inhibition of cell proliferation (Ki-67) and micro vascularization (CD31). The highest and lowest levels of tumor necrosis were observed in the intratumoral administration of TGFαL3-SEB (85 %) and PBS (14 %), respectively. Intratumoral injection of TGFαL3-SEB increased the lifespan of the mice so 37.5 % of them could survive for more than 6 months (p < 0.05). Overall, our findings indicated that intratumoral administration of TGFαL3-SEB effectively inhibited the growth of breast tumors through induction of necrosis and suppressing proliferation and angiogenesis without systemic toxicity.

Nimesulide-loaded nanoparticles for the potential coadjuvant treatment of prostate cancer

Nimesulide (NS)-loaded nanoparticles (NPNS) were prepared from polylactide-co-glycolide (PLGA) and eventually coated with chitosan (NPNSCS). Nanoparticles (NP) were spherical with sizes 379 ± 59 nm for NPNS and 393 ± 66 nm for NPNSCS and zeta potentials of -15 ± 3 mV for NPNS to 10 ± 4 mV for NPNSCS, suggesting an efficient coating. Drug encapsulation rate was high (88 ± 5% and 83 ± 7% of added drug) for NPNS and NPNSCS, respectively. After NP washing and re-suspension, 98 ± 2% and 99 ± 1% of the drug initially entrapped remained associated to NP. NS was dispersed in amorphous state within the polymeric matrix. Two-fold dilution of NP with pH 7.4 PBS provoked no drug release. However, 30-40% NS was released after a 1/10 dilution. NPNSCS and NPNS diluted 1/100 reduced the encapsulated drug to around 30% and 70%, respectively. In contrast, 100% NS was released from NP under sink conditions in less than 2h. The permeability of free-NS (1-1.5 × 10(-5)cm/s) was compared with NPNS (NPNS = 6.4-8.1 × 10(-6)cm/s and NPNSCS = 5.5-7.0 × 10(-6)cm/s) using the PAMPA assay. The cytotoxicity of free-NS and NS in NP on model prostate cancer cells PC-3 and DU-145 showed the highest cytotoxic effect with NPNSCS on PC-3 cells (IC50 = 89 μM).

Mono-guanidine heterolipid based SMEDDS: A promising tool for cytosolic delivery of antineoplastics

In the present work, we designed and synthesized a novel mono-guanidine heterolipid (MGH) and confirmed its structure by NMR and ESI-MS. The MGH was used as cationic lipid in developing etoposide loaded cationic self-microemulsifying drug delivery system (ECS) intended to be delivered by intratumoral route. The ECS exhibited size <50 nm and zeta potential +32.6 mV on dilution with various isotonic vehicles with no phase separation or drug precipitation. The ECS could be easily sterilized by membrane filtration method and showed excellent stability for 6 months. The ECS demonstrated excellent in vitro antiproliferative activity against B16F10 cells which is attributed to its high transfection efficiency and capability to cause prolonged drug release in cytosolic space. In vivo antitumor activity of ECS was conducted in B16F10 induced melanoma tumor model. ECS at 12 mg/kg dose showed superior tumor suppression ability and exhibited 100% survival compared to other formulations. Mice treated with ECS by intratumoral route, showed neither systemic side effect nor any evidences of hepatotoxicity and nephrotoxicity. In contrast, etoposide administered by intravenous route showed remarkable systemic toxicity, hepatotoxicity and nephrotoxicity.

Targeting hyaluronic acid family for cancer chemoprevention and therapy

Hyaluronic acid or hyaluronan (HA) is perhaps one of the most uncomplicated large polymers that regulates several normal physiological processes and, at the same time, contributes to the manifestation of a variety of chronic and acute diseases, including cancer. Members of the HA signaling pathway (HA synthases, HA receptors, and HYAL-1 hyaluronidase) have been experimentally shown to promote tumor growth, metastasis, and angiogenesis, and hence each of them is a potential target for cancer therapy. Furthermore, as these members are also overexpressed in a variety of carcinomas, targeting of the HA family is clinically relevant. A variety of targeted approaches have been developed to target various HA family members, including small-molecule inhibitors and antibody and vaccine therapies. These treatment approaches inhibit HA-mediated intracellular signaling that promotes tumor cell proliferation, motility, and invasion, as well as induction of endothelial cell functions. Being nontoxic, nonimmunogenic, and versatile for modifications, HA has been used in nanoparticle preparations for the targeted delivery of chemotherapy drugs and other anticancer compounds to tumor cells through interaction with cell-surface HA receptors. This review discusses basic and clinical translational aspects of targeting each HA family member and respective treatment approaches that have been described in the literature.

A comparison of covalent and noncovalent strategies for paclitaxel release using poly(ester amide) graft copolymer micelles

Micelles formed from amphiphilic copolymers are promising for the delivery of drug molecules, potentially leading to enhanced properties and efficacies. Critical aspects of these systems include the use of biocompatible, biodegradable polymer backbones as well as the ability to control the incorporation of drugs and their release rates. In this work, a poly(ester amide)–poly(ethylene oxide) graft copolymer with paclitaxel conjugated via ester linkages was prepared and assembled into micelles. For comparison, micelles with physically encapsulated paclitaxel were also prepared. The release rates of these two systems were studied, and the micelles with covalently conjugated paclitaxel exhibited a prolonged release of the drug in comparison to the noncovalent system, which rapidly released the payload. In vitro studies suggested that the poly(ester amide)–poly(ethylene oxide) copolymers were nontoxic, whereas the toxicities of the drug-loaded micelles were dependent on their release rates. Overall, these systems are promising for further development as anticancer drug carriers.

Controlled release and targeted delivery to cancer cells of doxorubicin from polysaccharide-functionalised single-walled carbon nanotubes

Carboxyl single-walled carbon nanotubes (SWNTs) were used to construct an innovative drug delivery system by modification with chitosan (CHI) to enhance water solubility and biocompatibility.

Polylactide-based paclitaxel-loaded nanoparticles fabricated by dispersion polymerization: characterization, evaluation in cancer cell lines, and preliminary biodistribution studies

The macromonomer method was used to prepare cross-linked, paclitaxel-loaded polylactide (PLA)-polyethylene glycol (stealth) nanoparticles using free-radical dispersion polymerization. The method can facilitate the attachment of other molecules to the nanoparticle surface to make it multifunctional. Proton nuclear magnetic resonance and Fourier transform infrared spectra confirm the synthesis of PLA macromonomer and cross-linking agent. The formation of stealth nanoparticles was confirmed by scanning and transmission electron microscopy. The drug release isotherm of paclitaxel-loaded nanoparticles shows that the encapsulated drug is released over 7 days. In vitro cytotoxicity assay in selected breast and ovarian cancer cell lines reveal that the blank nanoparticle is biocompatible compared with medium-only treated controls. In addition, the paclitaxel-loaded nanoparticles exhibit similar cytotoxicity compared with paclitaxel in solution. Confocal microscopy reveals that the nanoparticles are internalized by MCF-7 breast cancer cells within 1 h. Preliminary biodistribution studies also show nanoparticle accumulation in tumor xenograft model. The nanoparticles are suitable for the controlled delivery of bioactive agents.

Gold-gold sulfide nanoshell as a novel intensifier for anti-tumor effects of radiofrequency fields

OBJECTIVES

Several studies have been carried out to investigate the effect of various nanoparticles exposed to radiofrequency (RF) waves on cancerous tissues. In this study, a colon carcinoma tumor model was irradiated by RF in the presence of gold-gold sulfide (GGS) nanoshells.

MATERIALS AND METHODS

Synthesis and characterization of GGS nanoshells were initially performed. CT26 cells were subcutaneously injected into the flank of BALB/c mice to create the colon carcinoma tumor models. Then the tumors were subjected to different treatments. Treatment factors included intratumoral injection of GGS and RF radiation. Different groups were considered as control with no treatment, receiving GGS, RF irradiated and simultaneous administration of GGS and RF. Efficacy of the treatments was evaluated by daily monitoring of tumor volume and recording the relative changes in it, the time needed for a 5-fold increase in the volume of tumor (T5) and utilizing pathologic studies to determine the lost volume of the tumors.

RESULTS

In comparison with control group, tumor growth was not markedly inhibited in the groups receiving only GGS or RF, while in the group receiving GGS and RF, tumor growth was effectively inhibited compared with the other groups. In addition, the lost volume of the tumor and T5 was markedly higher in groups receiving GGS and RF compared with other groups.

CONCLUSION

This study showed that RF radiation can markedly reduce the tumor growth in presence of GGS. Hence, it can be predicted that GGS nanoshells convert sub-lethal effects of noninvasive RF fields into lethal damages.

Nanoparticles for localized delivery of hyaluronan oligomers towards regenerative repair of elastic matrix

Abdominal aortic aneurysms (AAAs) are rupture-prone progressive dilations of the infrarenal aorta due to a loss of elastic matrix that lead to weakening of the aortic wall. Therapies to coax biomimetic regenerative repair of the elastic matrix by resident, diseased vascular cells may thus be useful to slow, arrest or regress AAA growth. Hyaluronan oligomers (HA-o) have been shown to induce elastic matrix synthesis by healthy and aneurysmal rat aortic smooth muscle cells (SMCs) in vitro but only via exogenous dosing, which potentially has side-effects and limitations to in vivo delivery towards therapy. In this paper, we describe the development of HA-o loaded poly(lactide-co-glycolide) nanoparticles (NPs) for targeted, controlled and sustained delivery of HA-o towards the elastogenic induction of aneurysmal rat aortic SMCs. These NPs were able to deliver HA-o over an extended period (>30 days) at previously determined elastogenic doses (0.2-20 μg ml(-1)). HA-o released from the NPs led to dose-dependent increases in elastic matrix synthesis, and the recruitment and activity of lysyl oxidase, the enzyme which cross-links elastin precursor molecules into mature fibers/matrix. Therefore, we were able to successfully develop a nanoparticle-based system for controlled and sustained HA-o delivery for the in vitro elastogenic induction of aneurysmal rat aortic smooth muscle cells.

Multicompartimental nanoparticles for co-encapsulation and multimodal drug delivery to tumor cells and neovasculature

PURPOSE

The purpose of this work was the development of a multicompartimental nanocarrier for the simultaneous encapsulation of paclitaxel (PTX) and genistein (GEN), associating antiangiogenic and cytotoxic properties in order to potentiate antitumoral activity.

METHOD

Polymeric nanocapsules containing PTX were obtained by interfacial deposition of preformed polymer and coated with a phospholipid bilayer entrapping GEN. Physical-chemical and morphological characteristics were characterized, including size and size distribution, drug entrapment efficiency and drug release profile. In vivo studies were performed in EAT bearing Swiss mice.

RESULTS

Entrapment efficiency for both drugs in the nanoparticles was approximately 98%. Average particle diameter was 150 nm with a monomodal distribution. In vitro assays showed distinct temporal drug release profiles for each drug. The dose of 0.2 mg/kg/day of PTX resulted in 11% tumor inhibition, however the association of 12 mg/kg/day of GEN promoted 44% tumor inhibition and a 58% decrease in VEGF levels.

CONCLUSIONS

Nanoparticles containing GEN and PTX with a temporal pattern of drug release indicated that the combined effect of cytotoxic and antiangiogenic drugs present in the formulation contributed to the overall enhanced antitumor activity of the nanomedicine.

In vivo screening of S100B inhibitors for melanoma therapy

S100 proteins are markers for numerous cancers, and in many cases high S100 protein levels are a prognostic indicator for poor survival. One such case is S100B, which is overproduced in a very large percentage of malignant melanoma cases. Elevated S100B protein was more recently validated to have causative effects towards cancer progression via down-regulating the tumor suppressor protein, p53. Towards eliminating this problem in melanoma, targeting S100B with small molecule inhibitors was initiated. This work relies on numerous chemical biology technologies including structural biology, computer-aided drug design, compound screening, and medicinal chemistry approaches. Another important component of drug development is the ability to test compounds and various molecular scaffolds for their efficacy in vivo. This chapter briefly describes the development of S100B inhibitors, termed SBiXs, for melanoma therapy with a focus on the inclusion of in vivo screening at an early stage in the drug discovery process.

Paclitaxel Nano-Delivery Systems: A Comprehensive Review

Paclitaxel is one of the most effective chemotherapeutic drugs ever developed and is active against a broad range of cancers, such as lung, ovarian, and breast cancers. Due to its low water solubility, paclitaxel is formulated in a mixture of Cremophor EL and dehydrated ethanol (50:50, v/v) a combination known as Taxol. However, Taxol has some severe side effects related to Cremophor EL and ethanol. Therefore, there is an urgent need for the development of alternative Taxol formulations. The encapsulation of paclitaxel in biodegradable and non-toxic nano-delivery systems can protect the drug from degradation during circulation and in-turn protect the body from toxic side effects of the drug thereby lowering its toxicity, increasing its circulation half-life, exhibiting improved pharmacokinetic profiles, and demonstrating better patient compliance. Also, nanoparticle-based delivery systems can take advantage of the enhanced permeability and retention (EPR) effect for passive tumor targeting, therefore, they are promising carriers to improve the therapeutic index and decrease the side effects of paclitaxel. To date, paclitaxel albumin-bound nanoparticles (Abraxane®) have been approved by the FDA for the treatment of metastatic breast cancer and non-small cell lung cancer (NSCLC). In addition, there are a number of novel paclitaxel nanoparticle formulations in clinical trials. In this comprehensive review, several types of developed paclitaxel nano-delivery systems will be covered and discussed, such as polymeric nanoparticles, lipid-based formulations, polymer conjugates, inorganic nanoparticles, carbon nanotubes, nanocrystals, and cyclodextrin nanoparticles.

Nano-encapsulation of vitamin D3 active metabolites for application in chemotherapy: formulation study and in vitro evaluation

PURPOSE

Calcitriol (1,25-dihydroxyvitamin D3), the active metabolite of vitamin D3, is a potential anticancer agent but with high risk of hypercalcemia which limits the achievement of effective serum concentrations. Thus, calcitriol targeting delivery by nanoparticles may present a good solution.

METHODS

Vitamin D3 active metabolites were encapsulated into polymeric nanoparticles and different formulation parameters were tested. The growth inhibitory efficiency of these nanoparticles was carried out in vitro on human breast adenocarinoma cells (MCF-7).

RESULTS

Using cholecalciferol (the inactive metabolite), different polymer and oil ratios were compared to select nanoparticles presenting high encapsulation efficiency and sustained release profile. Calcidiol/calcitriol loaded nanoparticles had good encapsulation efficiencies (around 90%) associated with sustained releases over 7 days and enhanced stability. Moreover, loaded nanoparticles showed similar growth inhibition to non-encapsulated metabolites of vitamin D3 on day 4 and higher activities on days 7 and 10 after treatment initiation.

CONCLUSION

The nano-encapsulation of vitamin D3 active metabolites may offer a new and potentially effective strategy for vitamin D3-based chemotherapy overcoming its actual limitations. The targeting delivery of vitamin D3 metabolites should be encouraged.

Role of CD44 in tumour progression and strategies for targeting

CD44 or hyaluronan receptor is a transmembrane receptor associated with aggressive tumour growth, proliferation, and metastasis. In normal physiology, this receptor has a crucial role in cell adhesion, inflammation, and repair processes. However, many tumour cells over-express this receptor and abuse it to become progressive and perpetual units. The article comments from common functioning of the CD44 receptor, to its diabolic multi-dimensional effects in promotion of malignant cells. It also illuminates the relations of CD44 endorsed processes with other biomolecular events in cancer progression. In an end, the review focuses comprehensively at ongoing researches to exploit the CD44 over-expression as a probable target in treatment, management, and diagnosis of malignancy.

Lipid encapsulation of cationic polymers in hybrid nanocarriers reduces their non-specific toxicity to breast epithelial cells

PURPOSE

Clinical application of cationic polymers for delivery of nucleic acids has been limited by their toxicity. The purpose of this study is to evaluate whether the polymer-in-lipid hybrid nanotechnology recently developed for controlled siRNA delivery can tackle this toxicity issue by reducing exposure of the cellular components to free cationic polymers.

METHODS

Lipid-polymer hybrid nanocarriers (LPNs) encapsulating complexes of hexadecylated polyethylenimine (H-PEI) and biologically inactive siRNA in lipids were prepared at different lipid-polymer ratios. Comparative toxicity of these LPNs and unencapsulated cationic materials on breast epithelial cell lines MDA-MB-231 and MCF-10a was evaluated.

RESULTS

Even at a low lipid-polymer ratio (3:1 w/w), encapsulation of H-PEI improved its LC(50) values measured within hours by 3-5 fold, and caused less reduction in the colony-formation rates in 10-14 days. The observed reductions in the acute and delayed carrier toxicity were associated with significantly less membrane damages, improved mitochondrial functions, reduced reactive oxidative species production, and lower caspase-3 activity (all p < 0.05) without sacrificing the siRNA transfection efficiency.

CONCLUSIONS

This study has validated the hybrid nanotechnology for controlled RNA delivery from a toxicological perspective. This is especially valuable if local or long-term RNA therapy is intended for which low carrier toxicity is essential.

Intratumoral injection of taxol in vivo suppresses A549 tumor showing cytoplasmic vacuolization

Based on our recent in vitro studies, this report was designed to explore the mechanism by which high concentration of taxol (70 µM) induced paraptosis-like cell death in human lung carcinoma (A549) cells, and to evaluate the therapeutic efficacy of taxol using A549 tumor-bearing mice in vivo. Exposure of cells to taxol induced time-dependent cytotoxicity and cytoplasmic vacuolization without the involvement of Bax, Bak, Mcl-1, Bcl-XL, and caspase-3. Although taxol treatment induced activating transcription factor 6 (ATF6) cleavage indicative of endoplasmic reticulum (ER) stress, silencing ATF6 by shATF6 did not prevent taxol-induced both cytotoxcity and cytoplasmic vacuolization, suggesting that taxol-induced cytoplasmic vacuolization and cell death were not due to ER stress. Moreover, taxol-treated cells did not show DNA fragmentation and loss of mitochondrial membrane potential, the typical characteristics of apoptosis. In addition, taxol-induced cytoplasmic vacuolization did not show the cellular lysis, the characteristics of oncosis, and positive of β-galactosidase, the characteristic of senescence, indicating that taxol induced paraptosis-like cell death is neither oncosis nor senescence. Moreover, our in vivo data showed that intratumoral injection of taxol (50 mg/kg) in A549 tumor xenograft mice on day 1 and day 19 potently suppressed tumor growth showing significant ER vacuolization without toxicity. In conclusion, high concentration of taxol exhibits a significant anticancer activity by inducing paraptosis-like cell death in vitro and in vivo, without significant toxicity, suggesting a promising therapeutic strategy for apoptosis-resistance cancer by inducing ER vacuolization.

Advances in image-guided intratumoral drug delivery techniques

Image-guided drug delivery provides a means for treating a variety of diseases with minimal systemic involvement while concurrently monitoring treatment efficacy. These therapies are particularly useful to the field of interventional oncology, where elevation of tumor drug levels, reduction of systemic side effects and post-therapy assessment are essential. This review highlights three such image-guided procedures: transarterial chemoembolization, drug-eluting implants and convection-enhanced delivery. Advancements in medical imaging technology have resulted in a growing number of new applications, including image-guided drug delivery. This minimally invasive approach provides a comprehensive answer to many challenges with local drug delivery. Future evolution of imaging devices, image-acquisition techniques and multifunctional delivery agents will lead to a paradigm shift in patient care.

Effect of intratumoral administration on biodistribution of 64Cu-labeled nanoshells

BACKGROUND

Gold nanoshells are excellent agents for photothermal ablation cancer therapy and are currently under clinical trial for solid tumors. Previous studies showed that passive delivery of gold nanoshells through intravenous administration resulted in limited tumor accumulation, which represents a major challenge for this therapy. In this report, the impact of direct intratumoral administration on the pharmacokinetics and biodistribution of the nanoshells was systematically investigated.

METHODS

The gold nanoshells were labeled with the radionuclide, copper-64 ((64)Cu). Intratumoral infusion of (64)Cu-nanoshells and two controls, ie, (64)Cu-DOTA (1,4,7,10-tetraazaciclododecane- 1,4,7,10-tetraacetic acid) and (64)Cu-DOTA-PEG (polyethylene glycol), as well as intravenous injection of (64)Cu-nanoshells were performed in nude rats, each with a head and neck squamous cell carcinoma xenograft. The pharmacokinetics was determined by radioactive counting of serial blood samples collected from the rats at different time points post-injection. Using positron emission tomography/computed tomography imaging, the in vivo distribution of (64)Cu-nanoshells and the controls was monitored at various time points after injection. Organ biodistribution in the rats at 46 hours was analyzed by radioactive counting and compared between the different groups.

RESULTS

The resulting pharmacokinetic curves indicated a similar trend between the intratumorally injected agents, but a significant difference with the intravenously injected (64)Cu-nanoshells. Positron emission tomography images and organ biodistribution results on rats after intratumoral administration showed higher retention of (64)Cu-nanoshells in tumors and less concentration in other healthy organs, with a significant difference from the controls. It was also found that, compared with intravenous injection, tumor concentrations of (64)Cu-nanoshells improved substantially and were stable at 44 hours post-injection.

CONCLUSION

There was a higher intratumoral retention of (64)Cu-nanoshells and a lower concentration in other healthy tissues, suggesting that intratumoral administration is a potentially better approach for nanoshell-based photothermal therapy.

Sensitive and rapid HPLC quantification of tenofovir from hyaluronic acid-based nanomedicine

The purpose of this study was to develop and validate a rapid, sensitive, and specific reversed-phase high-performance liquid chromatography method for the quantitative determination of native tenofovir (TNF) for various applications. Different analytical performance parameters such as linearity, precision, accuracy, limit of quantification (LOQ), limit of detection (LOD), and robustness were determined according to International Conference on Harmonization (ICH) guidelines. A Bridge™ C18 column (150 × 4.6 mm, 5 μm) was used as stationary phase. The retention time of TNF was 1.54 ± 0.03 min (n = 6). The assay was linear over the concentration range of 0.1-10 μg/mL. The proposed method was sensitive with LOD and LOQ values equal to 50 and 100 ng/mL, respectively. The method was accurate with percent mean recovery from 95.41% to 102.90% and precise as percent RSD (relative standard deviation) values for intra-day, and inter-day precision were less than 2%. This method was utilized for the estimation of molar absorptivity of TNF at 259 nm (ε(259) = 12,518 L/mol/cm), calculated from linear regression analysis. The method was applied for determination of percentage of encapsulation efficiency (22.93 ± 0.04%), drug loading (12.25 ± 1.03%), in vitro drug release profile in the presence of enzyme (43% release in the first 3 h) and purification analysis of hyaluronic acid-based nanomedicine.

Paclitaxel in tyrosine-derived nanospheres as a potential anti-cancer agent: in vivo evaluation of toxicity and efficacy in comparison with paclitaxel in Cremophor

Paclitaxel (PTX) has gained widespread clinical use yet its administration is associated with significant toxicity. In the present study, the toxicity and anti-tumor efficacy of tyrosine-derived nanospheres (NSP) for the delivery of PTX was compared to a clinical formulation of PTX in PBS-diluted Cremophor® EL (PTX-CrEL-D). Maximum tolerated dose was determined using a concentration series of PTX in NSP and CrEL-D, with toxicity assessed by measuring changes in body weight. Healthy mice administered PTX-NSP continued to gain weight normally while treatment with PTX-CrEL-D resulted in significant weight loss that failed to recover following treatment. Even at the dose of 50mg/kg, PTX-NSP showed better tolerance than 25mg/kg of PTX-CrEL-D. Xenograft studies of breast cancer revealed that the anti-tumor efficacy of PTX-NSP was equal to that of PTX-CrEL-D in tumors originating from both MDA-MB-435 and ZR-75-1 cancer lines. Larger volume of distribution and longer half-life were measured for PTX-NSP administration compared to those reported in the literature for a CrEL formulation. This trend suggests the potential for improved therapeutic index of PTX when administered via NSP. The findings reported here confirm that the NSP formulation is an efficient method for PTX administration with significant increase in maximum tolerated dose, offering possible clinical implications in the treatment of breast tumors.

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.

Biomedical Applications of Biodegradable Polymers

Utilization of polymers as biomaterials has greatly impacted the advancement of modern medicine. Specifically, polymeric biomaterials that are biodegradable provide the significant advantage of being able to be broken down and removed after they have served their function. Applications are wide ranging with degradable polymers being used clinically as surgical sutures and implants. In order to fit functional demand, materials with desired physical, chemical, biological, biomechanical and degradation properties must be selected. Fortunately, a wide range of natural and synthetic degradable polymers has been investigated for biomedical applications with novel materials constantly being developed to meet new challenges. This review summarizes the most recent advances in the field over the past 4 years, specifically highlighting new and interesting discoveries in tissue engineering and drug delivery applications.

Polymeric drug delivery systems for localized cancer chemotherapy

Cancer has become one of the most difficult health challenges of our time, accounting for millions of deaths yearly. Systemic chemotherapy is the most common therapeutic approach; however, considerable limitations exist including toxicities to healthy tissues and low achievable drug concentrations at tumor sites. More than 85% of human cancers are solid tumors, which can greatly benefit from localized delivery. This approach allows for high drug concentrations at the target site, lower systemic toxicity, and extended drug exposure which may be beneficial for cell cycle-specific drugs. Polymers have been widely considered in the development of localized delivery systems. This review focuses on both natural and synthetic biodegradable polymers that have been explored for localized chemotherapy, exploring their advantages, disadvantages, and clinical potential while citing examples of their use in pre-clinical development.