Folate-targeted Nanoparticles Research Articles

Targeting Tamoxifen to Breast Cancer Xenograft Tumours: Preclinical Efficacy of Folate-Attached Nanoparticles Based on Alginate-Cysteine/Disulphide-Bond-Reduced Albumin

In vivo evaluation of tamoxifen (TMX)-loaded folate-targeted nanoparticles prepared from a mixture of disulphide bond reduced bovine serum albumin (BSA-SH) and alginate-cysteine (ALG-CYS) as targeted delivery systems of TMX to tumour tissues. TMX in solution, TMX included into folate-nanoparticles and their non-targeted analogues were intravenously administered to nude mice carrying xenograft MCF-7 tumours. The antitumor activity of these systems was characterized in terms of tumour growth rate, histological and immunohistochemical analysis of tumour tissues and TMX biodistribution. TMX-folate-attached nanoparticles caused tumour remission whereas free TMX or TMX-non-targeted nanoparticles could only stop the tumour development. The histological evaluation of tumour tissues showed that those treated with folate-conjugated systems presented the most quiescent and disorganized structures. Additionally, the lowest concentrations of TMX accumulated in non-targeted organs were also found after administration of the drug using this formulation. This study demonstrated that TMX-loaded folate-targeted systems were capable of reaching tumour sites, so enhancing the in vivo anticancer action of TMX, and allowing a new administration route to be applied and some of the current TMX therapy problems to be overcome.

Effect of Folate-Targeted Nanoparticle Size on Their Rates of Penetration into Solid Tumors

Targeted therapies are emerging as a preferred strategy for the treatment of cancer and other diseases. To evaluate the impact of a high affinity targeting ligand on the rate and extent of tumor penetration of different sized nanomedicines, we have used intravital multiphoton microscopy to quantitate the kinetics of tumor accumulation of a homologous series of folate-PEG-rhodamine conjugates prepared with polyethylene glycols (PEG) of different molecular weights. We demonstrate that increasing the size of the folate-PEG-rhodamine conjugates results in both longer circulation times and slower tumor penetration rates. Although a "binding site barrier" is observed with the folate-linked polymers in folate receptor expressing tumors, ligand targeting eventually leads to increased tumor accumulation, with endocytosis of the targeted nanocarriers contributing to their enhanced tumor retention. Because the effects of nanocarrier size, shape, chemistry, and targeting ligand are interconnected and complex, we suggest that these parameters must be carefully optimized for each nanocarrier to ensure optimal drug delivery in vivo.

Folate-Targeted Nanoparticles Based on Albumin and Albumin/Alginate Mixtures as Controlled Release Systems of Tamoxifen: Synthesis and In Vitro Characterization

Preparation and in vitro characterization of tamoxifen (TMX)-loaded folate-targeted nanoparticles based on disulfide bond reduced bovine serum albumin (BSA-SH) and BSA-SH/alginate-cysteine (BSA-SH/ALG-CYS) mixtures as drug delivery systems. Folate-nanoparticles were characterized in terms of folate content, morphology, size, zeta potential, TMX load and drug release kinetics. Additionally, cell viability and cellular uptake of nanoparticles were determined using different cancer cell lines. Folic acid (FOL) was successfully attached to nanoparticles (ranging between 79 and170μmol folate/g NP). Nanoparticles with 76-417nm mean size were obtained and loaded with TMX (4.2-7.7μg/mg NP). Zeta potential and drug extraction revealed major superficial placement of the drug, especially in the case of BSA/ALG-FOL systems. Drug release studies in the presence of surfactant showed a gradual release of the drug between 4-7h. In general, low cytotoxicity of unloaded systems was found. Internalization of the systems was achieved and mediated by folate receptor, especially in the case of BSA NP-FOL. The administration of 10μM TMX by TMX-FOL NP showed their efficacy as controlled TMX release systems. Promising anticancer action of these new TMX-loaded folate-targeted systems was demonstrated, allowing a new administration route to be studied in further in vivo studies in order to improve current TMX therapy.

Abstract 4517: Differential cellular response to nanoparticle docetaxel and docetaxel at sub-therapeutic dose range.

Abstract Nanoparticle (NP) formulations of taxanes overcome the need for excipients and improve the delivery of taxane therapeutics to tumors. These advantages have resulted in rapid clinical translation of NP taxanes and high interest in preclinical and clinical development of novel NP taxanes. However, the effects of NP taxanes on tumor cells compared to their small molecule counterparts have not been evaluated. Existing NP taxanes are polymeric NPs and release their cargo in a slow and controlled fashion. Due to this controlled release, the taxane concentration level and exposure time to a cell at any given time from NP taxanes are different from that of small molecule taxanes. We have utilized two distinct polymeric NP docetaxel formulations to study the influence of NP drug delivery of taxanes on tumor cells in vitro. We hypothesize that the cellular response to polymeric NP taxanes is different from that of small molecule taxanes due to the controlled release property. We used docetaxel (Dtxl) as a model taxane therapeutic and studied tumor cell response to Docetaxel-PNP, a commercial polymeric NP formulation of Dtxl currently under clinical investigation, and folate-targeted nanoparticle docetaxel (FT-NP Dtxl), a targeted lipid-polymer NP formulation of Dtxl that was developed by our laboratory. The taxane formulations were evaluated using KB head and neck carcinoma. We performed liquid chromatography/mass spectrometry and determined that using the Dtxl equivalent dose of the Dtxl formulations provided the same intracellular concentration of Dtxl after 1 h exposure in KB cells. We demonstrated by fluorescence-activated cell sorting of the cell cycle distribution that NP Dtxl formulations and small molecule Dtxl have similar effects on KB tumor cells at therapeutic concentrations. However, cells treated with a sub-therapeutic concentration of NP Dtxl undergo a different progression through the cell cycle compared to cells treated with small molecule Dtxl, which suggests a difference in the cellular response between the Dtxl formulations. We validated the differential cellular response to sub-therapeutic doses of NP Dtxl and Dtxl by live cell imaging analysis of KB green fluorescent protein-histone 2B (GFP-H2B) expressing cells after treatment. We found that the cellular response of tumor cells to NP Dtxl is different from that of Dtxl at sub-therapeutic doses. In this dose range, we also found that the cellular response of cells to NP Dtxl is similar to that of Dtxl at a much lower dose, suggesting that controlled release property of NP Dtxl is responsible for the difference in the cellular response. In conclusion, we have demonstrated that the cellular response of tumor cells to NP Dtxl is different from that to Dtxl at sub-therapeutic doses. We speculate that this difference is due to the controlled release property, which causes cells to be exposed to a lower concentration of Dtxl. Citation Format: Edina C. Wang, Rebecca Sinnott, Michael E. Werner, Manish Sethi, Joel E. Tepper, Angelique W. Whitehurst, Andrew Z. Wang. Differential cellular response to nanoparticle docetaxel and docetaxel at sub-therapeutic dose range. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4517. doi:10.1158/1538-7445.AM2013-4517

99mTc-labelled nanosystem as tumour imaging agent for SPECT and SPECT/CT modalities

We report the synthesis, in vitro and in vivo investigation of folate-targeted, biocompatible, biodegradable self-assembled nanoparticles radiolabelled with (99m)Tc, as potential new SPECT or SPECT/CT imaging agent. Nanoparticles with hydrodynamic size in the range of 75-200 nm were prepared by self-assembly of chitosan and folated poly-γ-glutamic acid, and then radiolabelled with (99m)Tc. The nanoparticles target tumour cells overexpressing folate receptors and internalize specifically into them to realize early tumour diagnosis detected by SPECT and SPECT/CT modalities. Rat hepatocellular carcinoma cells were used as model system. Cell specificity and tumour targeting efficacy of these nanosystems were investigated in vitro, and in vivo using SPECT and fusion nanoSPECT/CT imaging. In vitro results showed that the radiolabeled nanosystem was efficiently internalized by tumour cells. Whole-body biodistribution of the new radiolabelled, folate-targeted nanoparticles revealed higher uptake in the tumorous kidney compared to the non-tumorous contralateral side. Uptake by the lungs and thyroids was negligible, which confirmed the stability of the nanoparticles in vivo. In vivo SPECT and SPECT/CT imaging visually reinforced the uptake results and were in accordance with the biodistribution data: the new nanoparticles as a targeted contrast agent improve tumour targeting and are able to detect folate-receptor-overexpressing tumours in animal models with enhanced contrast.

Escorted for Efficacy

Nanoparticles targeting macrophage folate receptors can increase the efficacy of methotrexate therapy for arthritis.

Folate-Targeted Polymeric Nanoparticle Formulation of Docetaxel Is an Effective Molecularly Targeted Radiosensitizer with Efficacy Dependent on the Timing of Radiotherapy

Nanoparticle (NP) chemotherapeutics hold great potential as radiosensitizers. Their unique properties, such as preferential accumulation in tumors and their ability to target tumors through molecular targeting ligands, are ideally suited for radiosensitization. We aimed to develop a molecularly targeted nanoparticle formulation of docetaxel (Dtxl) and evaluate its property as a radiosensitizer. Using a biodegradable and biocompatible lipid-polymer NP platform and folate as a molecular targeting ligand, we engineered a folate-targeted nanoparticle (FT-NP) formulation of Dtxl. These NPs have sizes of 72 ± 4 nm and surface charges of -42 ± 8 mV. Using folate receptor overexpressing KB cells and folate receptor low HTB-43 cells, we showed folate-mediated intracellular uptake of NPs. In vitro radiosensitization studies initially showed FT-NP is less effective than Dtxl as a radiosensitizer. However, the radiosensitization efficacy is dependent on the timing of radiotherapy. In vitro radiosensitization conducted with irradiation given at the optimal time (24 h) showed FT-NP Dtxl is as effective as Dtxl. When FT-NP Dtxl is compared to Dtxl and nontargeted nanoparticle (NT-NP) Dtxl in vivo, FT-NP was found to be significantly more effective than Dtxl or NT-NP Dtxl as a radiosensitizer. We also confirmed that radiosensitization is dependent on timing of irradiation in vivo. In summary, FT-NP Dtxl is an effective radiosensitizer in folate-receptor overexpressing tumor cells. Time of irradiation is critical in achieving maximal efficacy with this nanoparticle platform. To the best of our knowledge, our report is the first to demonstrate the potential of molecularly targeted NPs as a promising new class of radiosensitizers.

Folate-targeted Nanoparticle Formulation of Docetaxel as an Effective Biologically Targeted Radiosensitizer for Head and Neck Cancer

Folate-targeted Nanoparticle Formulation of Docetaxel as an Effective Biologically Targeted Radiosensitizer for Head and Neck Cancer

Folate‐targeted nanoparticles show efficacy in the treatment of inflammatory arthritis

To investigate the uptake of a poly(amidoamine) dendrimer (generation 5 [G5]) nanoparticle covalently conjugated to polyvalent folic acid (FA) as the targeting ligand into macrophages, and to investigate the activity of an FA- and methotrexate (MTX)-conjugated dendrimer (G5-FA-MTX) as a therapeutic for the inflammatory disease of arthritis. In vitro studies were performed in macrophage cell lines and in isolated mouse macrophages to check the cellular uptake of fluorescence-tagged G5-FA nanoparticles, using flow cytometry and confocal microscopy. In vivo studies were conducted in a rat model of collagen-induced arthritis to evaluate the therapeutic potential of G5-FA-MTX. Folate-targeted dendrimer bound and internalized in a receptor-specific manner into both folate receptor β-expressing macrophage cell lines and primary mouse macrophages. The conjugate G5-FA-MTX acted as a potent antiinflammatory agent and reduced arthritis-induced parameters of inflammation such as ankle swelling, paw volume, cartilage damage, bone resorption, and body weight decrease. The use of folate-targeted nanoparticles to specifically target MTX into macrophages may provide an effective clinical approach for antiinflammatory therapy in rheumatoid arthritis.

Folate-targeted nanoparticle delivery of chemo- and radiotherapeutics for the treatment of ovarian cancer peritoneal metastasis

Peritoneal metastasis is a major cause of morbidity and mortality in ovarian cancer. While intraperitoneal chemotherapy and radiotherapy have shown favorable clinical results, both are limited by their non-targeted nature. We aimed to develop a biologically targeted nanoparticle therapeutic for the treatment of ovarian cancer peritoneal metastasis. Folate-targeted nanoparticles encapsulating chemotherapy and/or radiotherapy were engineered. Paclitaxel (Ptxl) was used as the chemotherapeutic and yittrium-90 ( 90Y) was employed as the therapeutic radioisotope. Folate was utilized as the targeting ligand as most ovarian cancers overexpress the folate receptor. Nanoparticle characterization studies showed monodispersed particles with controlled Ptxl release. Folate targeting ligand mediated the uptake of NPs into tumor cells. In vitro efficacy studies demonstrated folate-targeted NPs containing chemoradiotherapy was the most effective therapeutic compared to folate-targeted NPs containing a single therapeutic or any non-targeted NP therapeutics. In vivo efficacy studies using an ovarian peritoneal metastasis model showed that folate-targeted NP therapeutics were significantly more effective than non-targeted NP therapeutics. Among the folate-targeted therapeutics, the NP containing chemoradiotherapy appeared to be the most effective. Our results suggest that folate-targeted nanoparticles containing chemoradiotherapy have the potential as a treatment for ovarian peritoneal metastasis.

Abstract 382: Evaluation of folate-targeted ChemoRad nanoparticle as intraperitoneal chemoradiotherapy for ovarian cancer

Abstract Approximately 15,000 women die of ovarian cancer in the U.S. each year. One of the most common causes of mortality in these patients is peritoneal metastases. While intraperitoneal (IP) chemotherapy and IP radioisotope therapy have shown favorable clinical results, both lead to significant toxicities. Chemoradiotherapy has been shown to be superior to either therapy alone in many cancers, such as head and neck cancer, cervical cancer and rectal cancer. However it has not been evaluated in ovarian cancer due to concerns of toxicity. Advances in nanotechnology have enabled the development of biologically targeted nanoparticle (NP) therapeutic carriers. These NPs allow preferential delivery of therapeutics to tumors, which in turn increases efficacy and minimizes toxicity. Our laboratory was the first to develop a nanoparticle platform, the ChemoRad NP, which can deliver both chemotherapy and radiotherapy. We hypothesized that a ChemoRad NP targeted against ovarian cancer cells can be a novel and effective treatment for ovarian peritoneal metastases. In this study, we engineered a folate-targeted ChemoRad NP encapsulating paclitaxel and Y90 for IP chemoradiotherapy of ovarian cancer. The NP was evaluated using the SKOV-3 ovarian carcinoma cell line and a murine model of ovarian peritoneal metastases. Folate was utilized as a targeting ligand as most ovarian cancers overexpress the folate receptor. Paclitaxel (Ptxl), a first-line chemotherapy for ovarian cancer, was used as the model drug. Y90 was employed as the therapeutic radioisotope based on its high-energy emission and low toxicity. The folate-targeted ChemoRad NP was formulated by a nanoprecipitation method. The resulting NPs have a hydrophobic polymeric core where Ptxl is encapsulated. The NP surface is covered by a self-assembled monolayer of lipid and lipid-polymer. Metal chelators were incorporated into the sub-surface layer for the chelation of Y90. Characterization of the NPs showed particle size of 70+/−5 nm and 60% Ptxl encapsulation efficiency. Drug release study showed controlled release with more than 95% of Ptxl released at 24 hrs. We demonstrated folate mediated cellular uptake of targeted NP Ptxl Y90 by SKOV-3 cells. An in vitro efficacy study showed the folate-targeted NP Ptxl Y90 (T-NP Ptxl Y90) is more effective than that of non-targeted NP Ptxl Y90. We then validated our folate NP containing Ptxl and Y90 in vivo. Peritoneal xenograft metastases were induced by injecting SKOV-3 cells IP in nude mice. Therapeutics were given IP at 3 weeks post tumor implantation. We were able to demonstrate that T-NP Ptxl Y90 is more effective than T-NP Ptxl, T-NP Y90, and non-targeted NPs containing either or both therapeutic agents. In conclusion, we have demonstrated that folate-targeted NP Ptxl Y90 is a biologically targeted chemoradiotherapy for ovarian cancer. It represents a potential novel treatment for ovarian peritoneal metastases. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 382. doi:10.1158/1538-7445.AM2011-382

In search of the Holy Grail: Folate-targeted nanoparticles for cancer therapy

Targeted drug therapy or “smart” drug delivery, potentially combined with simultaneous imaging modalities to monitor the delivery of drugs to specific tissues, is arguably the “holy grail” of pharmacology. Therapeutic approaches that exploit nanoparticles to deliver drugs selectively to cancer cells are currently considered one of the most promising avenues in the area of cancer therapeutics and imaging. The potential to deliver active chemotherapeutic drugs in the vicinity or directly within specific tumors via receptor mediated pathways, and to image tumors through the use of nanoparticles has been conceptually and experimentally shown for several classes of nanoparticles. Nanoparticles functionalized with the vitamin folic acid are of particular interest as a variety of malignant tumors are known to overexpress the folate receptor(s). Indeed, several nanoparticle architectures with improved retention time, administration route, biocompatibility, absorption, and clearance are being proposed and are in late stage clinical development. This commentary highlights some of the most important concepts related to nanoparticles and folate-mediated drug delivery and imaging in cancer research.

Evaluation of Folate-targeted Nanoparticle Formulation of Docetaxel as a Radiosensitizer in Head and Neck Cancer

Nanoparticle (NP) therapeutics is poised to make a major impact on cancer treatment. NPs have been shown to preferentially accumulate in tumors, which leads to superior biodistribution and lower toxicity when compared to conventional small molecule chemotherapeutics. The next generation of NP chemotherapeutics are biologically targeted and composed of biodegradable materials that allow controlled release of drugs. Although they hold high promise as radiosensitizers, preclinical evaluation is necessary given NPs' different mode of cell entry and drug release profile compared to that of free drugs.

Preparation and in vitro evaluation of actively targetable nanoparticles for SN-38 delivery against HT-29 cell lines

SN-38 (7-ethyl-10-hydroxycamptothecin) is the active metabolite of irinotecan, which is 100-to 1000-fold more cytotoxic than irinotecan. Nevertheless, extreme hydrophobicity of SN-38 has prevented its clinical use. One way of improving the solubility and stability of SN-38 is to formulate the drug into nanoparticles. Folic acid has been widely used as a targeting moiety for various anticancer drugs. For folate-receptor–targeted anticancer therapy, SN-38 nanoparticles were produced using poly-lactide- co-glycolide–polyethylene glycol–folate (PLGA-PEG-FOL) conjugate by emulsification/solvent evaporation method. The FOL-conjugated di-block copolymer was synthesized by coupling the PLGA-PEG-NH 2 di-block copolymer with an activated folic acid. The conjugates were used for the formation of SN-38 nanoparticles with an average size of 200 nm in diameter. The SN-38 targeted nanoparticles showed a greater cytotoxicity against HT-29 cancer cells than SN-38 nontargeted nanoparticles. These results suggested that folate-targeted nanoparticles could be a potentially useful delivery system for SN-38 as an anticancer agent. From the Clinical Editor SN-38 is the active metabolite of the chemotherapy agent irinotecan, which is 100-1000 fold more cytotoxic than irinotecan, but its extreme hydrophobicity has prevented its clinical use. In this paper, the authors present a nanotechnology-based approach targeting the folate-receptor with SN-38 loaded nanoparticles, demonstrating stronger cytotoxicity against HT-29 cancer cells than with control nanoparticles.