Natalie D. Cummings

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 ((90)Y) 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.

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.

Revival of the abandoned therapeutic wortmannin by nanoparticle drug delivery

One of the promises of nanoparticle (NP) carriers is the reformulation of promising therapeutics that have failed clinical development due to pharmacologic challenges. However, current nanomedicine research has been focused on the delivery of established and novel therapeutics. Here we demonstrate proof of the principle of using NPs to revive the clinical potential of abandoned compounds using wortmannin (Wtmn) as a model drug. Wtmn is a potent inhibitor of phosphatidylinositol 3′ kinase-related kinases but failed clinical translation due to drug-delivery challenges. We engineered a NP formulation of Wtmn and demonstrated that NP Wtmn has higher solubility and lower toxicity compared with Wtmn. To establish the clinical translation potential of NP Wtmn, we evaluated the therapeutic as a radiosensitizer in vitro and in vivo. NP Wtmn was found to be a potent radiosensitizer and was significantly more effective than the commonly used radiosensitizer cisplatin in vitro in three cancer cell lines. The mechanism of action of NP Wtmn radiosensitization was found to be through the inhibition of DNA-dependent protein kinase phosphorylation. Finally, NP Wtmn was shown to be an effective radiosensitizer in vivo using two murine xenograft models of cancer. Our results demonstrate that NP drug-delivery systems can promote the readoption of abandoned drugs such as Wtmn by overcoming drug-delivery challenges.

Polysilsesquioxane Nanoparticles for Triggered Release of Cisplatin and Effective Cancer Chemoradiotherapy

Chemoradiotherapy is a well-established treatment paradigm in oncology. There has been strong interest in identifying strategies to further improve its therapeutic index. An innovative strategy is to utilize nanoparticle (NP) chemotherapeutics in chemoradiation. Since the most commonly utilized chemotherapeutic with radiotherapy is cisplatin, the development of an NP cisplatin for chemoradiotherapy has the highest potential impact on this treatment. Here, we report the development of an NP comprised of polysilsesquioxane (PSQ) polymer crosslinked by a cisplatin prodrug (Cisplatin-PSQ) and its utilization in chemoradiotherapy using non-small cell lung cancer as a disease model. Cisplatin-PSQ NP has an exceptionally high loading of cisplatin. Cisplatin-PSQ NPs were evaluated in chemoradiotherapy in vitro and in vivo. They demonstrated significantly higher therapeutic efficacy when compared to cisplatin. These results suggest that the Cisplatin-PSQ NP holds potential for clinical translation in chemoradiotherapy.

Abstract 1333: Organ specific biomatrix scaffolds for ex vivo characterization of colorectal cancer metastases

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Colorectal cancer is the second leading cause of cancer-related deaths in the United States with more than 140,000 new cases being diagnosed this year. However, morbidity and mortality is not generally caused by the primary tumor, but by metastases to other organs. There are few models in which to study colorectal cancer metastasis, either in two-dimensional (2D) monolayer tissue culture or in animal xenografts. Both of these models have limitations. Standard 2D tissue culture, though inexpensive and accessible, poorly mimics the metastatic process and xenograft models are costly and technically challenging. Two of the most common sites of colorectal metastasis are the liver and lungs, however, there are few ex vivo models in which to study metastases to these sites. Advances in materials science have led to the development of ex vivo tissue specific models of extracellular matrices (ECM). We have utilized a novel material, biomatrix scaffolds, to engineer a colorectal cancer metastasis ex vivo model. We hypothesized that through the use of liver and lung specific biomatrix, (1) we can better characterize the colorectal cancer metastatic process by mimicking the organ specific microenvironment and (2) more accurately determine the response to therapeutic agents to treat metastases. In this study, we characterized biomatrix derived from rat liver and lung as a growth substrate for human colon cancer cell lines. We used the human colon cancer derived cell lines: HT29, SW480, CaCo2 and Lovo. Chemotherapeutic response to oxaliplatin, irinotecan and 5-fluorouracil for these cell lines grown on biomatrix was examined. We also used primary cultures of colorectal cancer metastases derived from patient samples. The biomatrix scaffolds were generated through decellularization of rat liver or lungs. We preformed mass spectrometry and determined the ECM composition and the associated growth factors found in lysates of liver and lung remain bound to the biomatrix in concentrations similar to those found in vivo. Colorectal cancer cell lines demonstrated different growth rates and morphologies when grown on biomatrix, resulting in organized, 3-dimenasional growth of non-hollow spheroids several hundred microns in diameter. We demonstrated differential responses to chemotherapeutics and observed differential gene expression via microarray analysis when colorectal cancer cell lines were grown on biomatrix compared to plastic, collagen, or matrigel. We also demonstrated increased tumor cell colony formation in primary cultures of patient derived colorectal metastases on biomatrix compared to plastic or collagen. In conclusion, we have developed a decellularized tissue material, biomatrix, that can provide an ex vivo model of colorectal cancer metastasis to aid in therapeutic drug development and genetic characterization of metastasis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1333. doi:1538-7445.AM2012-1333

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

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL 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