Antitumor activity of hydrophilic Paclitaxel copolymer prodrug using locoregional delivery in human orthotopic non-small cell lung cancer xenograft models

Protein and peptide delivery to lungs by using advanced targeted drug delivery

The challenges and difficulties associated with conventional drug delivery systems have led to the emergence of novel, advanced targeted drug delivery systems. Therapeutic drug delivery of proteins and peptides to the lungs is complicated owing to the large size and polar characteristics of the latter. Nevertheless, the pulmonary route has attracted great interest today among formulation scientists, as it has evolved into one of the important targeted drug delivery platforms for the delivery of peptides, and related compounds effectively to the lungs, primarily for the management and treatment of chronic lung diseases. In this review, we have discussed and summarized the current scenario and recent developments in targeted delivery of proteins and peptide-based drugs to the lungs. Moreover, we have also highlighted the advantages of pulmonary drug delivery over conventional drug delivery approaches for peptide-based drugs, in terms of efficacy, retention time and other important pharmacokinetic parameters. The review also highlights the future perspectives and the impact of targeted drug delivery on peptide-based drugs in the coming decade.

Surface-engineered smart nanocarrier-based inhalation formulations for targeted lung cancer chemotherapy: a review of current practices

Lung cancer is the second most common and lethal cancer in the world. Chemotherapy is the preferred treatment modality for lung cancer and prolongs patient survival by effective controlling of tumor growth. However, owing to the nonspecific delivery of anticancer drugs, systemic chemotherapy has limited clinical efficacy and significant systemic adverse effects. Inhalation routes, on the other hand, allow for direct delivery of drugs to the lungs in high local concentrations, enhancing their anti-tumor activity with minimum side effects. Preliminary research studies have shown that inhaled chemotherapy may be tolerated with manageable adverse effects such as bronchospasm and cough. Enhancing the anticancer drugs deposition in tumor cells and limiting their distribution to other healthy cells will therefore increase their clinical efficacy and decrease their local and systemic toxicities. Because of the controlled release and localization of tumors, nanoparticle formulations are a viable option for the delivery of chemotherapeutics to lung cancers via inhalation. The respiratory tract physiology and lung clearance mechanisms are the key barriers to the effective deposition and preservation of inhaled nanoparticle formulations in the lungs. Designing and creating smart nanoformulations to optimize lung deposition, minimize pulmonary clearance, and improve cancerous tissue targeting have been the subject of recent research studies. This review focuses on recent examples of work in this area, along with the opportunities and challenges for the pulmonary delivery of smart nanoformulations to treat lung cancers.

Advanced Nanoparticle-Based Drug Delivery Systems and Their Cellular Evaluation for Non-Small Cell Lung Cancer Treatment

Lung cancers, the number one cancer killer, can be broadly divided into small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC), with NSCLC being the most commonly diagnosed type. Anticancer agents for NSCLC suffer from various limitations that can be partly overcome by the application of nanomedicines. Nanoparticles is a branch within nanomedicine that can improve the delivery of anticancer drugs, whilst ensuring the stability and sufficient bioavailability following administration. There are many publications available in the literature exploring different types of nanoparticles from different materials. The effectiveness of a treatment option needs to be validated in suitable in vitro and/or in vivo models. This includes the developed nanoparticles, to prove their safety and efficacy. Many researchers have turned towards in vitro models that use normal cells or specific cells from diseased tissues. However, in cellular works, the physiological dynamics that is available in the body could not be mimicked entirely, and hence, there is still possible development of false positive or false negative results from the in vitro models. This article provides an overview of NSCLC, the different nanoparticles available to date, and in vitro evaluation of the nanoparticles. Different types of cells suitable for in vitro study and the important precautions to limit the development of false results are also extensively discussed.

Present Situation and Future Progress of Inhaled Lung Cancer Therapy: Necessity of Inhaled Formulations with Drug Delivery Functions

Inhaled lung cancer therapy is promising because of direct and noninvasive drug delivery to the lungs with low potential for severe systemic toxicity. Thus chemotherapeutic drugs have been administered clinically by nebulization of solution or suspension formulations, which demonstrated their limited pulmonary absorption and relatively mild systemic toxicity. In all these clinical trials, however, there was no obviously superior anticancer efficacy in lung cancer patients even at the maximum doses of drugs limited by pulmonary toxicity. Therefore methods that deliver both higher anticancer efficacy and lower pulmonary toxicity are strongly desired. In addition to the worldwide availability of pressured metered dose inhalers (pMDIs) and dry powder inhalers (DPIs) to treat local respiratory diseases, recent innovations in medicines and technologies are encouraging next steps toward effective inhaled lung cancer therapy with new therapeutic or drug delivery concepts. These include the discovery of target cells/molecules and drug candidates for novel cancer therapy, the development of high-performance inhalation devices for effective pulmonary drug delivery, and the establishment of manufacturing technologies for functional nanoparticles/microparticles. This review highlights the present situation and future progress of inhaled drugs for lung cancer therapy, including an overview of available inhalation devices, pharmacokinetics, and outcomes in clinical trials so far and some novel formulation strategies based on drug delivery systems to achieve enhanced anticancer efficacy and attenuated pulmonary toxicity.

Inhaled Submicron Particle Paclitaxel (NanoPac) Induces Tumor Regression and Immune Cell Infiltration in an Orthotopic Athymic Nude Rat Model of Non-Small Cell Lung Cancer

Background: This study evaluated the antineoplastic and immunostimulatory effects of inhaled (IH) submicron particle paclitaxel (NanoPac^®) in an orthotopic non-small cell lung cancer rodent model.

Methods: Male nude rats were whole body irradiated, intratracheally instilled with Calu-3 cancer cells and divided into six treatment arms (n = 20 each): no treatment (Group 1); intravenous nab-paclitaxel at 5.0 mg/kg once weekly for 3 weeks (Group 2); IH NanoPac at 0.5 or 1.0 mg/kg, once weekly for 4 weeks (Groups 3 and 4), or twice weekly for 4 weeks (Groups 5 and 6). Upon necropsy, left lungs were paraffin embedded, serially sectioned, and stained for histopathological examination. A subset was evaluated by immunohistochemistry (IHC), anti-pan cytokeratin staining AE1/AE3⁺ tumor cells and CD11b⁺ staining dendritic cells, natural killer lymphocytes, and macrophage immune cells (n = 2, Group 1; n = 3 each for Groups 2–6). BCL-6 staining identified B lymphocytes (n = 1 in Groups 1, 2, and 6).

Results: All animals survived to scheduled necropsy, exhibited no adverse clinical observations due to treatment, and gained weight at the same rate throughout the study. Histopathological evaluation of Group 1 lung samples was consistent with unabated tumor growth. Group 2 exhibited regression in 10% of animals (n = 2/20). IH NanoPac-treated groups exhibited significantly higher tumor regression incidence per group (n = 11–13/20; p < 0.05, χ²). IHC subset analysis revealed tumor-nodule cluster separation, irregular borders between tumor and non-neoplastic tissue, and an increased density of infiltrating CD11b⁺ cells in Group 2 animals (n = 2/3) and in all IH NanoPac-treated animals reviewed (n = 3/3 per group). A single animal in Group 4 and Group 6 exhibited signs of pathological complete response at necropsy with organizing stroma and immune cells replacing areas presumed to have previously contained adenocarcinoma nodules.

Conclusion: Tumor regression and immune cell infiltration were observed in all treatment groups, with an increased incidence noted in animals receiving IH submicron particle paclitaxel treatment.

Pulmonary delivery of nanoparticle chemotherapy for the treatment of lung cancers: challenges and opportunities

Lung cancer is the second most prevalent and the deadliest among all cancer types. Chemotherapy is recommended for lung cancers to control tumor growth and to prolong patient survival. Systemic chemotherapy typically has very limited efficacy as well as severe systemic adverse effects, which are often attributed to the distribution of anticancer drugs to non-targeted sites. In contrast, inhalation routes permit the delivery of drugs directly to the lungs providing high local concentrations that may enhance the anti-tumor effect while alleviating systemic adverse effects. Preliminary studies in animals and humans have suggested that most inhaled chemotherapies are tolerable with manageable pulmonary adverse effects, including cough and bronchospasm. Promoting the deposition of anticancer drugs in tumorous cells and minimizing access to healthy lung cells can further augment the efficacy and reduce the risk of local toxicities caused by inhaled chemotherapy. Sustained release and tumor localization characteristics make nanoparticle formulations a promising candidate for the inhaled delivery of chemotherapeutic agents against lung cancers. However, the physiology of respiratory tracts and lung clearance mechanisms present key barriers for the effective deposition and retention of inhaled nanoparticle formulations in the lungs. Recent research has focused on the development of novel formulations to maximize lung deposition and to minimize pulmonary clearance of inhaled nanoparticles. This article systematically reviews the challenges and opportunities for the pulmonary delivery of nanoparticle formulations for the treatment of lung cancers.

PEGylation of paclitaxel largely improves its safety and anti-tumor efficacy following pulmonary delivery in a mouse model of lung carcinoma

Pulmonary delivery offers an attractive route of administration for chemotherapeutic agents, with the advantages of high drug concentrations locally and low side effects systemically. However, fast clearance mechanisms result in short residence time of small molecule drugs in the lungs. Moreover, the local toxicity induced by antineoplastic drugs is considered a major obstacle for the clinical application of inhaled chemotherapy. In this study, we explored the utility of 6kDa and 20kDa polyethylene glycol-paclitaxel (PEG-PTX) conjugates to retain paclitaxel within the lungs, achieve its sustained release locally, and thereby, improve its efficacy and reduce its pulmonary toxicity. The conjugates increased the maximum tolerated dose of paclitaxel by up to 100-fold following intratracheal instillation in healthy mice. PEG-PTX conjugates induced lung inflammation. However, the inflammation was lower than that induced by an equivalent dose of the free drug and it was reversible. Conjugation of paclitaxel to both PEG sizes significantly enhanced its anti-tumor efficacy following intratracheal instillation of a single dose in a Lewis lung carcinoma model in mice. PEG-PTX 20k showed equivalent efficacy as PEG-PTX 6k delivered at a 2.5-fold higher dose, suggesting that the molecular weight of the conjugate plays a role in anti-cancer activity. PEG-PTX 20k conjugate presented a prolonged residency and a sustained paclitaxel release within the lungs. This study showed that PEGylation of paclitaxel offers a potential delivery system for inhalation with improved anti-cancer efficacy, prolonged exposure of lung-resident tumors to the antineoplastic drug and reduced local toxicity.

Development of a novel orthotopic non-small cell lung cancer model and therapeutic benefit of 2'-(2-bromohexadecanoyl)-docetaxel conjugate nanoparticles

The aims of these studies were to establish an orthotopic non-small-cell lung cancer (NSCLC) mouse model and to investigate the therapeutic efficacy of lipid-based nanoparticles (NPs) containing 2'-(2-bromohexadecanoyl)-docetaxel (Br-C16-DX) in this new model. A novel orthotopic NSCLC model was established in nude mice through a dorsal side injection of luciferase-expressing A549 cells. The model was characterized by a survival study, histological staining, bioluminescence imaging and PET/CT imaging. The therapeutic efficacy of the Br-C16-DX NPs versus Taxotere® was investigated in this model. The results demonstrated that mouse survival time was significantly prolonged by weekly intravenous administration of the NPs or Taxotere. Furthermore, the NP group had 35 days longer progression-free survival and 27 days longer median survival compared to the Taxotere group. It was concluded that the developed orthotopic NSCLC model represents a feasible, reproducible, and clinically relevant experimental mouse model to test current and potential therapies including nanomedicines. From the clinical editor: This team of authors has developed an orthotopic non-small cell lung cancer model, and demonstrates that it represents a feasible, reproducible, and clinically relevant experimental mouse model to test current and potential therapies including nanomedicines.

Orthotopic lung cancer murine model by nonoperative transbronchial approach

PURPOSE

The aim of this work was to establish a novel orthotopic human non-small cell lung cancer (NSCLC) murine xenograft model by a nonsurgical, transbronchial approach.

DESCRIPTION

Male athymic nude mice and human NSCLC cell lines, including A549, H460, and H520 were used. Under direct visualization of the vocal cords, a 23-gauge blunt-tip slightly curved metal catheter was introduced into the trachea to the bronchus, and 2.5×10(5) tumor cells mixed with Matrigel (BD Biosciences, Mississauga, Ontario, Canada) were administered into the lung. Mice were monitored using weekly microcomputed tomography scans for tumor formation.

EVALUATION

When the tumor size reached more than 4 mm in diameter, the animals were euthanized, and the tumor tissue was evaluated histopathologically. Of 37 mice studied, 34 were confirmed to have tumor formation: 29 developed solitary tumors and 5 had multifocal lesions. There was no evidence of extrapleural dissemination or effusion.

CONCLUSIONS

Transbronchial delivery of tumor cells enabled the establishment of a novel orthotopic human NSCLC murine xenograft model. This clinically relevant preclinical model bearing a solitary nodule is of value for a variety of in vivo research studies.

Efficacy versus safety concerns for aerosol chemotherapy in non-small-cell lung cancer: a future dilemma for micro-oncology

Inhaled chemotherapy was first used more than 30 years ago. Since then, numerous chemotherapeutic agents have been used in either in vitro or in vivo studies. Several aspects of the methodology of the drug administration have been thoroughly demonstrated and explained. However, the safety concerns of these studies were not thoroughly investigated and different results regarding the same drug formulations have been reported. There are cases where the studies failed to demonstrate the long-term effects of the chemotherapeutic drug formulations to the lung parenchyma. Acute and latent effects observed in a small number of human trial studies are still under investigation of inhaled chemotherapy administration. This review provides data regarding all up-to-date inhaled chemotherapy studies and presents the methodological parameters of the safety measures incorporated. In addition, a commentary regarding the safety concerns for the medical staff participating in these studies will be presented.

Antitumor activity and molecular dynamics simulations of paclitaxel-laden triazine dendrimers

The antitumor activities of triazine dendrimers bearing paclitaxel, a well-known mitotic inhibitor, are evaluated in SCID mice bearing human prostate cancer xenografts. To increase the activity of a first generation prodrug 1 that contained twelve paclitaxel molecules tethered via an ester linkage, the new construct described here, prodrug 2, tethers paclitaxel with linkers containing both an ester and disulfide. While PEGylation is necessary for solubility, and may improve biocompatibility and increase plasma half-life, it increases the heterogeneity of the sample with an average of eight to nine PEG chains (2 kDa each) incorporated. The heterogeneous population of PEGylated materials was used without fractionation based on models obtained from molecular dynamics simulations. Three models were examined; hexaPEGylated, nonaPEGylated, and dodecaPEGylated constructs. Intravenous delivery of prodrug 2 was performed by single, double or triple dosing regimes with doses spaced by one week. The doses varied from 50 mg of paclitaxel/kg to 200 mg of paclitaxel/kg. Tumor growth arrest and regression was observed over the 10-week treatment period without mortality for mice treated with the 50 mg of paclitaxel/kg treated three times.

Paclitaxel loaded PEG(5000)-DSPE micelles as pulmonary delivery platform: formulation characterization, tissue distribution, plasma pharmacokinetics, and toxicological evaluation

The objective of the present study was to evaluate the potential of paclitaxel loaded micelles fabricated from PEG(5000)-DSPE as a sustained release system following pulmonary delivery. PEG(5000)-DSPE micelles containing paclitaxel were prepared by solvent evaporation technique followed by investigation of in vitro release of paclitaxel in lung simulated fluid. Tissue distribution and plasma pharmacokinetics of the PEG-lipid micelles after intratracheal and intravenous administrations were investigated in addition to intratracheally administered taxol. Finally, toxicological profile of PEG(5000)-DSPE was investigated. Paclitaxel was successfully formulated in PEG-lipid micelles with encapsulation efficiency of 95%. The PEG-lipid micelles exhibited a sustained release behavior in the simulated lung fluid. Intratracheally administered polymeric micellar paclitaxel showed highest accumulation of paclitaxel in the lungs with AUC(0-12) in lungs being 45-fold higher than intravenously administered formulation and 3-fold higher than intratracheally delivered taxol. Paclitaxel concentration in other non-targeted tissues and plasma were significantly lower as compared to other groups. Furthermore, toxicity studies showed no significant increase in levels of lung injury markers in PEG(5000)-DSPE treated group as compared to saline-treated group. PEG(5000)-DSPE micelles delivered intratracheally were able to sustain highest paclitaxel concentrations in lungs for long periods of time, thus apprehending their suitability as pulmonary drug carriers.

Clinically relevant anticancer polymer Paclitaxel therapeutics

The concept of utilizing polymers in drug delivery has been extensively explored for improving the therapeutic index of small molecule drugs. In general, polymers can be used as polymer-drug conjugates or polymeric micelles. Each unique application mandates its own chemistry and controlled release of active drugs. Each polymer exhibits its own intrinsic issues providing the advantage of flexibility. However, none have as yet been approved by the U.S. Food and Drug Administration. General aspects of polymer and nano-particle therapeutics have been reviewed. Here we focus this review on specific clinically relevant anticancer polymer paclitaxel therapeutics. We emphasize their chemistry and formulation, in vitro activity on some human cancer cell lines, plasma pharmacokinetics and tumor accumulation, in vivo efficacy, and clinical outcomes. Furthermore, we include a short review of our recent developments of a novel poly(L-g-glutamylglutamine)-paclitaxel nano-conjugate (PGG-PTX). PGG-PTX has its own unique property of forming nano-particles. It has also been shown to possess a favorable profile of pharmacokinetics and to exhibit efficacious potency. This review might shed light on designing new and better polymer paclitaxel therapeutics for potential anticancer applications in the clinic.

Biological assessment of triazine dendrimer: toxicological profiles, solution behavior, biodistribution, drug release and efficacy in a PEGylated, paclitaxel construct

The physicochemical characteristics, in vitro properties, and in vivo toxicity and efficacy of a third generation triazine dendrimer bearing approximately nine 2 kDa polyethylene glycol chains and twelve ester linked paclitaxel groups are reported. The hydrodynamic diameter of the neutral construct varies slightly with aqueous solvent ranging from 15.6 to 19.4 nm. Mass spectrometry and light scattering suggest radically different molecular weights with the former approximately 40 kDa mass consistent with expectation, and the latter 400 kDa mass consistent with a decameric structure and the observed hydrodynamic radii. HPLC can be used to assess purity as well as paclitaxel release, which is insignificant in organic solvents or aqueous solutions at neutral and low pH. Paclitaxel release occurs in vitro in human, rat, and mouse plasma and is nonlinear, ranging from 7 to 20% cumulative release over a 48 h incubation period. The construct is 2-3 orders of magnitude less toxic than Taxol by weight in human hepatocarcinoma (Hep G2), porcine renal proximal tubule (LLC-PK1), and human colon carcinoma (LS174T) cells, but shows similar cytotoxicity to Abraxane in LS174T cells. Both Taxol and the construct appear to induce caspase 3-dependent apoptosis. The construct shows a low level of endotoxin, is not hemolytic and does not induce platelet aggregation in vitro, but does appear to reduce collagen-induced platelet aggregation in vitro. Furthermore, the dendrimer formulation slightly activates the complement system in vitro due most likely to the presence of trace amounts (<1%) of free paclitaxel. An animal study provided insight into the maximum tolerated dose (MTD) wherein 10, 25, 50, and 100 mg of paclitaxel/kg of construct or Abraxane were administered once per week for three consecutive weeks to non tumor bearing athymic nude mice. The construct showed in vivo toxicity comparable to that of Abraxane. Both formulations were found to be nontoxic at the administered doses, and the dendrimer had an acute MTD greater than the highest dose administered. In a prostate tumor model (PC-3-h-luc), efficacy was observed over 70 days with an arrest of tumor growth and lack of luciferase activity observed in the twice treated cohort.

[Establishment of orthotopic Lewis lung cancer model in mouse]

背景与目的

肺癌原位模型包括小鼠自发性肺肿瘤模型和气道内接种模型等，但自发性肺肿瘤模型耗时较长且成瘤率不能保证，而气道内接种模型成瘤部位及大小不稳定。本研究以3LL细胞系细胞接种于C57BL/6小鼠肺原位，与皮下接种模型比较，探讨其稳定性、转移特性，并建立小鼠肺原位癌模型的优化方法。

方法

将不同数量级的3LL细胞分别直接接种于C57BL/6小鼠左侧腋下制备皮下接种模型和以Matrigel悬浮后接种于其左肺制备原位接种模型，观察两种模型的生存期，并对小鼠进行解剖后行病理切片检查、免疫组化染色检测微血管密度、流式细胞仪检测CD44v。

结果

皮下组成瘤率分别为100%、66.7%、16.7%，未见明显转移。原位组成瘤率分别为100%、100%、83.3%，并可转移至对侧胸廓及肺脏。原位组中位生存期（38 d、35 d、23 d）明显少于皮下接种组（82 d、72 d、50 d）。原位接种组微血管密度（120.2±9.73）高于皮下组（92.6±7.12）。原位接种组肿瘤细胞悬液CD44v表达（26.46±1.56）%高于皮下接种组（23.13±1.02）%。

结论

以3LL细胞接种于小鼠肺部所建立的肺癌原位模型简单可靠，重复性高，具有较皮下接种模型更强的转移特性。

Anti-cancer effect of celecoxib and aerosolized docetaxel against human non-small cell lung cancer cell line, A549

Direct delivery of chemotherapeutic agents to the lung can increase both the drug concentration and exposure period to lung tumours. The objective of this study was to formulate docetaxel (DOC) into a metered dose inhaler (MDI), assess its aerodynamic characteristics and to evaluate the effect of celecoxib (CXB), a cyclooxygenase-2 (COX-2) inhibitor, on the in-vitro cytotoxicity and apoptotic response of aerosolized DOC against human lung adenocarcinoma cell line A549. A stable solution-type MDI formulation was developed with 0.25% DOC and 15% w/w ethyl alcohol using HFA 134a propellant. The formulation was evaluated for medication delivery, mass median aerodynamic diameter (MMAD), geometric standard deviation (GSD), percent throat deposition, respirable mass and respirable fraction. A six-stage viable impactor was used to assess the in-vitro cytotoxicity of DOC-MDI alone or in combination with CXB. Induction of apoptosis in A549 cells by DOC (non-aerosolized and aerosolized) in combination with CXB was evaluated by established techniques, such as caspase-3 estimation and terminal deoxynucleotidyl transferase-mediated nick end labelling (TUNEL) staining. The influence of different treatments on the expression of COX-2 and peroxisome proliferator-activated receptor-γ (PPAR-γ) in A549 cells was studied by RT-PCR. The DOC-MDI formulation had a MMAD of 1.58 μm, (GSD = 3.2) and a medication delivery of 80 μg/shot. DOC-MDI (one shot) in combination with CXB (10 μg mL−1) had a cell kill of more than 80% as determined by in-vitro cytotoxicity assay. The specific caspase-3 activity in A549 cells treated with DOC (0.01 μg mL−1) and CXB (10.0 μg mL−1) combination was 4 times higher than CXB and untreated control group, respectively. Further, TUNEL staining showed significant apoptosis of A549 cells treated with aerosolized DOC alone or in combination with CXB when compared with CXB and untreated cells. The RT-PCR experiments showed similar expression of COX-2 in both control and treated groups. PPAR-γ expression was increased in the combination treatment (0.01 μg mL−1 DOC and 10 μg mL−1 CXB) as compared with control (untreated), DOC (0.01 μg mL−1) and CXB (10 μg mL−1) treatments. Our results indicate the potential of inhalation delivery of DOC in the treatment of lung cancer.

Circulating human interleukin-8 as an indicator of cancer progression in a nude rat orthotopic human non-small cell lung carcinoma model

Clinically relevant animal models of human cancer are necessary for the evaluation of putative therapeutics. We hypothesized that circulating human lung cancer-associated proteins would correlate with physiologic measurements from an orthotopic H460 human non-small cell lung carcinoma model that we developed in immunodeficient rats. Physiologic measurements and serum samples were collected over time. Serum interleukin-8 (IL-8), p53, vascular endothelial growth factor, and matrix metalloproteinase-9 were quantitated for correlation with physiologic measurements. Matrix metalloproteinase-9 and p53 were not significantly detectable. Circulating vascular endothelial growth factor was detected at high levels in some tumor-bearing animals. Human IL-8 was detectable in all tumor-bearing animals and correlated positively with markers of respiratory acidosis (pH, P = 0.012; TCO(2), P = 0.024; pCO(2), P = 0.007; and HCO(3)(-), P = 0.029) and with surface body temperature (P = 0.001) beginning on day 16 after implantation. IL-8 levels negatively correlated with survival (P < 0.001), indicating an association with tumor burden. Circulating human IL-8 might be a useful, clinically relevant circulating tumor protein marker due to its positive correlation with multiple physiologic variables associated with lung cancer progression.

Microbial Biosynthesis of Polyglutamic Acid Biopolymer and Applications in the Biopharmaceutical, Biomedical and Food Industries

This review article provides an updated critical literature review on the production and applications of Polyglutamic Acid (PGA). alpha-PGA is synthesized chemically, whereas gamma-PGA can be produced by a number of microbial species, most prominently various Bacilli. Great insight into the microbial formation of gamma-PGA has been gained thanks to the development of molecular biological techniques. Moreover, there is a great variety of applications for both isoforms of PGA, many of which have not been discovered until recently. These applications include: wastewater treatment, food products, drug delivery, medical adhesives, vaccines, PGA nanoparticles for on-site drug release in cancer chemotherapy, and tissue engineering.

In vitro and in vivo evaluation of microparticulate drug delivery systems composed of macromolecular prodrugs

Macromolecular prodrugs are very useful systems for achieving controlled drug release and drug targeting. In particular, various macromolecule-antitumor drug conjugates enhance the effectiveness and improve the toxic side effects. Also, polymeric micro- and nanoparticles have been actively examined and their in vivo behaviors elucidated, and it has been realized that their particle characteristics are very useful to control drug behavior. Recently, researches based on the combination of the concepts of macromolecular prodrugs and micro- or nanoparticles have been reported, although they are limited. Macromolecular prodrugs enable drugs to be released at a certain controlled release rate based on the features of the macromolecule-drug linkage. Micro- and nanoparticles can control in vivo behavior based on their size, surface charge and surface structure. These merits are expected for systems produced by the combination of each concept. In this review, several micro- or nanoparticles composed of macromolecule-drug conjugates are described for their preparation, in vitro properties and/or in vivo behavior.

Design, synthesis and applications of hyaluronic acid-paclitaxel bioconjugates

Paclitaxel (1a), a well known antitumor agent adopted mainly for the treatment of breast and ovarian cancer, suffers from significant disadvantages such as low solubility, certain toxicity and specific drug-resistance of some tumor cells. To overcome these problems extensive research has been carried out. Among the various proposed strategies, the conjugation of paclitaxel (1a) to a biocompatible polymer, such as hyaluronic acid (HA, 2), has also been considered. Coupling a bioactive compound to a biocompatible polymer offers, in general, many advantages such as better drug solubilization, better stabilization, specific localization and controlled release. Hereafter the design, synthesis and applications of hyaluronic acid-paclitaxel bioconjugates are reviewed. An overview of HA-paclitaxel combinations is also given.

Hyaluronic acid-paclitaxel: antitumor efficacy against CD44(+) human ovarian carcinoma xenografts

Numerous human tumor types, including ovarian cancer, display a significant expression of the CD44 family of cell surface proteoglycans. To develop tumor-targeted drugs, we have initially evaluated whether the CD44 ligand hyaluronic acid (HA) could serve as a backbone for paclitaxel (TXL) prodrugs. HA-TXL was prepared by modification of previous techniques. The in vitro cytotoxicity of HA-TXL against the CD44(+) human ovarian carcinoma cell lines SKOV-3ip and NMP-1 could be significantly blocked by preincubation with a molar excess of free HA. Female nude mice bearing intraperitoneal implants of NMP-1 cells were treated intraperitoneally with a single sub-maximum tolerated dose dose of HA-TXL or with multiple-dose regimens of paclitaxel (Taxol; Mead Johnson, Princeton, NJ) to determine the effects of these regimens on host survival and intraperitoneal tumor burden, with the latter being assessed by magnetic resonance imaging. NMP-1 xenografts were highly resistant to Taxol regimens, as host survival was only nominally improved compared to controls (T//C approximately 120), whereas single-dose HA-TXL treatment significantly improved survival in this model (T//C approximately 140; P = .004). In both NMP-1 and SKOV-3ip models, MR images of abdomens of HA-TXL-treated mice obtained shortly before controls required humane sacrifice revealed markedly reduced tumor burdens compared to control mice. This study is among the first to demonstrate that HA-based prodrugs administered locoregionally have antitumor activity in vivo.

Inhalation delivery and anti-tumor activity of celecoxib in human orthotopic non-small cell lung cancer xenograft model

PURPOSE

To determine the in vivo anti-tumor effect of aerosolized Celecoxib (Cxb) in combination with i.v Docetaxel (Doc) and compare the anti-tumor effect with oral Cxb combined with i.v Doc in human orthotopic non-small cell lung cancer (NSCLC) xenograft model.

MATERIALS AND METHODS

Female Nu/Nu mice were implanted with orthotopic tumors by injecting A549 cells into the lung parenchyma. Seven day after tumor implantation the mice were treated with aerosolized Cxb (30 min exposure/day, 5 mg/ml solution) + i.v Doc (10 mg/kg) and the effect was compared with oral Cxb (150 mg/kg/day) + i.v Doc (10 mg/kg), for 28 days. Small-animal nose only inhalation chamber (CH Technologies, Westwood, NJ) was utilized for aerosol exposure. Therapeutic activity of Cxb (aerosol/oral) + Doc was estimated by differences in lung weight, tumor area and animal body weight. Lung tumor samples isolated from mice were analyzed for (a) PGE2 levels by enzyme immunoassay (EIA) (b) expression of Fas and Factor VIII by immunohistochemistry (c) IL-8 expression using EIA kits and (d) mRNA expression for caspase-3 by Real-Time PCR.

RESULTS

Mice treated with Cxb (aerosol/oral) + Doc showed significant reduction (P < 0.001) in lung weight and tumor area as compared to Cxb or Doc treatments. Cxb (aerosol/oral) + Doc showed increased apoptosis mediated via increased Fas and caspase-3 (P < 0.001) expression as compared to untreated control. Further, the combination treatment showed antiangiogenic effect as demonstrated by reduced expression of Factor VIII, IL-8 (P < 0.001) and PGE2 (P < 0.001) in lung tumors as compared to untreated control. Aerosolized Cxb at a significantly lower therapeutic dose (4.56 mg/kg/day) demonstrated comparable anti-tumor efficacy to orally administered Cxb (150 mg/kg/day).

CONCLUSION

Cxb was formulated and effectively delivered via aerosolization to treat orthotopic lung tumors in combination with i.v Doc. Cxb when administered by aerosol produced same therapeutic effect as oral Cxb, but at lower therapeutic dose and thus shows promise for the treatment of lung cancer.

In vitro and in vivo studies of a novel potential anticancer agent of isochaihulactone on human lung cancer A549 cells

We previously demonstrated that the crude acetone extract of Bupleurum scorzonerifolium (BS-AE) 60 microg/ml has anti-proliferation activity and apoptotic effects on A549 non-small cell lung cancer (NSCLC). A novel lignan, isochaihulactone (4-benzo[1,3]dioxol-5-ylmethyl-3(3,4,5-trimethoxyl-benzylidene)-dihydro-furan-2-one), was isolated from BS-AE and identified from spectral evidence ((1)H NMR, (13)C NMR, IR, and MS) and by comparison with authentic synthetic standards. Isochaihulactone was cytotoxic (IC(50)=10-50 microM) in a variety of human tumor cell lines. In in vitro and in vivo microtubule assembly assays, it inhibited tubulin polymerization in a concentration-dependent manner. As determined by flow cytometry, isochaihulactone caused G2/M phase arrest and apoptosis in a time- and concentration-dependent manner. G2/M arrest was correlated with increased p21/WAF1 levels, downregulation of the checkpoint proteins cyclin B1/cdc2 and mobility shift of cdc25C. Moreover, isochaihulactone (30 and 50 mg/kg) inhibited the growth of non-small cell lung carcinoma A549 xenograft in nude mice. These findings indicate isochaihulactone is a promising new antimitotic anticancer compound with potential for clinical application in the future.