A novel nanodelivery system for combination tumor therapy

Thesis (S.M.)--Massachusetts Institute of Technology, Biological Engineering Division, 2004.Includes bibliographical references (leaves 36-38).Anti-angiogenic therapy offers many benefits over traditional cytotoxic chemotherapy including fewer toxic side effects and the reduced development of drug resistance. Anti-angiogenics alone have not proven effective in inducing tumor regression in the clinic due to both the cytostatic nature of anti-angiogenic therapy and the potential formation of new regions of hypoxia within the tumor after therapy. The new therapeutic paradigm is for combining both anti-angiogenics and traditional cytotoxic agents for a synergistic effect. The efficacy of cytotoxic agents may be reduced after anti-angiogenic therapy, however, due to limited access to tumor vasculature and hypoxia-induced drug resistance. We propose that loading cytotoxic agents within the tumor prior to blood vessel collapse will enable both greater drug accumulation within the tumor as well as a reduction in the formation of therapy-induced regions of hypoxia. We present here a novel nanodelivery vehicle termed a 'nanocell' for the spatio-temporal recruitment of both anti-angiogenics and cytotoxic agents within the solid tumor to achieve this goal. Nanocells consist of a polymeric nanocore encapsulating the cytostatic agent doxorubicin surrounded by a lipid vesicle containing the anti-angiogenic agent combretastatin A4.(cont.) Nanocell treatment resulted in an 88% reduction in tumor size in vivo, compared to a 66% reduction in tumor size after delivering combretastatin A4 lipid vesicles and doxorubicin nanocores simultaneously but separately. Nanocell treatment also resulted in a significant reduction in systemic toxicity, fewer metastases to the lung and liver, and a greater degree of tumor apoptosis.by David A. Eavarone.S.M

A Voxel-Based Monte Carlo Model of Drug Release from Bulk Eroding Nanoparticles

The use of polymeric nanoparticles as drug delivery devices is becoming increasingly prevalent in a variety of therapeutic applications. Despite their widespread clinical use, the factors influencing the release profiles of nanoparticle-encapsulated drugs are still not quantitatively understood. We present here a new, semi-empirical model of drug release from polymeric nanoparticles using a formulation of dexamethasone encapsulated within poly(lactic-co-glycolic acid) to set model parameters. We introduce a three-dimensional voxel-based framework for Monte Carlo simulations that enables direct investigation of the entire spherical nanoparticle during particle degradation and drug release. Due to implementation of this model at the nanoscale, we utilize assumptions that simplify the model while still allowing multi-phase drug release to be simulated with good correlation to experimental results. In the future, emerging mechanistic understandings of nanoparticle drug release may be integrated into this simulation framework to increase predictive power.National Institutes of Health (U.S.) (GM57073

A novel nanoscale delivery system for spatio-temporal delivery of combination chemotherapy

Thesis (Ph. D. in Biomedical Engineering)--Harvard-MIT Division of Health Sciences and Technology, 2009.Cataloged from PDF version of thesis.Includes bibliographical references.In the continuing search for effective treatments for cancer, the emerging model is the combination of traditional chemotherapy with anti-angiogenesis agents that inhibit blood vessel growth. However, the implementation of this strategy has faced two major obstacles. First, the long-term shutdown of tumor blood vessels by the anti-angiogenesis agent can prevent the tumor from receiving a therapeutic concentration of the chemotherapy agent. Second, inhibiting blood supply drives the formation of intra-tumoral hypoxia, or a lack of oxygen, which has been correlated with increased tumor invasiveness and resistance to chemotherapy. In this thesis we report the disease-driven engineering of a drug delivery system, a 'nanocell', which overcomes these barriers unique to solid tumors. The nanocell comprises a nuclear nanoparticle encapsulated within a lipid membrane and is preferentially taken up by the tumor. The nanocell delivers a temporal release of two drugs within the tumor core: the outer lipid envelope first releases an anti-angiogenesis agent, causing a vascular shutdown; the inner nanoparticle, which is trapped inside the tumor, then releases a chemotherapy agent. This focal release within the tumor targets cells most at risk for hypoxia and results in improved therapeutic index with reduced toxicity. The technology can be extended to additional agents, so as to target multiple signaling pathways or distinct tumor compartments, enabling the model of an 'integrative' approach in cancer therapy.(cont.) In the second part of the thesis we report new tools for the optimization of nanocell formulations. We present a new, three-dimensional, voxel-based computational model for Monte Carlo simulations of nanoparticle delivery systems that enables direct investigation of the entire vehicle during particle degradation and drug release. Use of this model in combination with emerging mechanistic understandings of nanoparticle drug release will facilitate optimization of nanocell combination therapy release profiles. We additionally report the generation and characterization of a set of carbohydrate-based chemotherapeutic agents that have the potential for use in nanocells as reduced toxicity alternatives to traditional chemotherapy agents.by David A. Eavarone.Ph.D.in Biomedical Engineerin

Glycome and Transcriptome Regulation of Vasculogenesis

Background— Therapeutic vasculogenesis is an emerging concept that can potentially be harnessed for the management of ischemic pathologies. The present study elucidates the potential coregulation of vasculogenesis by the heparan sulfate glycosaminoglycan–rich cell-surface glycome and the transcriptome. Methods and Results— Differentiation of embryonic stem cells into endothelial cells in an in vitro embryoid body is paralleled by an amplification of heparan sulfate glycosaminoglycan sulfation, which correlates with the levels of the enzyme N-deacetylase/N-sulfotransferase 1 (NDST1). Small hairpin RNA–mediated knockdown of NDST1 or modification of heparan sulfate glycosaminoglycans in embryonic stem cells with heparinases or sodium chlorate inhibited differentiation of embryonic stem cells into endothelial cells. This was translated to an in vivo zebrafish embryo model, in which the genetic knockdown of NDST1 resulted in impaired vascularization characterized by a concentration-dependent decrease in intersegmental vessel lumen and a large tail-vessel configuration, which could be rescued by use of exogenous sulfated heparan sulfate glycosaminoglycans. To explore the cross talk between the glycome and the transcriptome during vasculogenesis, we identified by microarray and then validated wild-type and NDST1 knockdown–associated gene-expression patterns in zebrafish embryos. Temporal analysis at 3 developmental stages critical for vasculogenesis revealed a cascade of pathways that may mediate glycocalyx regulation of vasculogenesis. These pathways were intimately connected to cell signaling, cell survival, and cell fate determination. Specifically, we demonstrated that forkhead box O3A/5 proteins and insulin-like growth factor were key downstream signals in this process. Conclusions— The present study for the first time implicates interplay between the glycome and the transcriptome during vasculogenesis, revealing the possibility of harnessing specific cellular glyco-microenvironments for therapeutic vascularization

Nanomaterials for Neural Interfaces

This review focuses on the application of nanomaterials for neural interfacing. The junction between nanotechnology and neural tissues can be particularly worthy of scientific attention for several reasons: (i) Neural cells are electroactive, and the electronic properties of nanostructures can be tailored to match the charge transport requirements of electrical cellular interfacing. (ii) The unique mechanical and chemical properties of nanomaterials are critical for integration with neural tissue as long-term implants. (iii) Solutions to many critical problems in neural biology/medicine are limited by the availability of specialized materials. (iv) Neuronal stimulation is needed for a variety of common and severe health problems. This confluence of need, accumulated expertise, and potential impact on the well-being of people suggests the potential of nanomaterials to revolutionize the field of neural interfacing. In this review, we begin with foundational topics, such as the current status of neural electrode (NE) technology, the key challenges facing the practical utilization of NEs, and the potential advantages of nanostructures as components of chronic implants. After that the detailed account of toxicology and biocompatibility of nanomaterials in respect to neural tissues is given. Next, we cover a variety of specific applications of nanoengineered devices, including drug delivery, imaging, topographic patterning, electrode design, nanoscale transistors for high-resolution neural interfacing, and photoactivated interfaces. We also critically evaluate the specific properties of particular nanomaterials—including nanoparticles, nanowires, and carbon nanotubes—that can be taken advantage of in neuroprosthetic devices. The most promising future areas of research and practical device engineering are discussed as a conclusion to the review.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/64336/1/3970_ftp.pd

Humanized anti-Sialyl-Tn antibodies for the treatment of ovarian carcinoma.

The expression of Sialyl-Tn (STn) in tumors is associated with metastatic disease, poor prognosis, and reduced overall survival. STn is expressed on ovarian cancer biomarkers including CA-125 (MUC16) and MUC1, and elevated serum levels of STn in ovarian cancer patients correlate with lower five-year survival rates. In the current study, we humanized novel anti-STn antibodies and demonstrated the retention of nanomolar (nM) target affinity while maintaining STn antigen selectivity. STn antibodies conjugated to Monomethyl Auristatin E (MMAE-ADCs) demonstrated in vitro cytotoxicity specific to STn-expressing ovarian cancer cell lines and tumor growth inhibition in vivo with both ovarian cancer cell line- and patient-derived xenograft models. We further validated the clinical potential of these STn-ADCs through tissue cross-reactivity and cynomolgus monkey toxicity studies. No membrane staining for STn was present in any organs of human or cynomolgus monkey origin, and the toxicity profile was favorable and only revealed MMAE-class associated events with none being attributed to the targeting of STn. The up-regulation of STn in ovarian carcinoma in combination with high affinity and STn-specific selectivity of the mAbs presented herein warrant further investigation for anti-STn antibody-drug conjugates in the clinical setting

Novel anti-Sialyl-Tn monoclonal antibodies and antibody-drug conjugates demonstrate tumor specificity and anti-tumor activity

ABSTRACT Targeted therapeutics that can differentiate between normal and malignant tumor cells represent the ideal standard for the development of a successful anti-cancer strategy. The Sialyl-Thomsen-nouveau antigen (STn or Sialyl-Tn, also known as CD175s) is rarely seen in normal adult tissues, but it is abundantly expressed in many types of human epithelial cancers. We have identified novel antibodies that specifically target with high affinity the STn glycan independent of its carrier protein, affording the potential to recognize a wider array of cancer-specific sialylated proteins. A panel of murine monoclonal anti-STn therapeutic antibodies were generated and their binding specificity and efficacy were characterized in vitro and in in vivo murine cancer models. A subset of these antibodies were conjugated to monomethyl auristatin E (MMAE) to generate antibody-drug conjugates (ADCs). These ADCs demonstrated in vitro efficacy in STn-expressing cell lines and significant tumor growth inhibition in STn-expressing tumor xenograft cancer models with no evidence of overt toxicity

Treatment of ovarian cancer by targeting the tumor stem cell-associated carbohydrate antigen, Sialyl-Thomsen-nouveau

Recurrent ovarian cancer (OvCa) is thought to result in part from the inability to eliminate rare quiescent cancer stem cells (CSCs) that survive cytotoxic chemotherapy and drive tumor resurgence. The Sialyl-Thomsen-nouveau antigen (STn) is a carbohydrate moiety present on protein markers of CSCs in pancreatic, colon, and gastric malignancies. We have demonstrated that human OvCa cell lines contain varying levels of cells that independently express either STn or the ovarian CSC marker CD133. Here we determine co-expression of STn and CD133 in a subset of human OvCa cell lines. Analyses of colony and sphere forming capacity and of response to standard-of-care cytotoxic therapy suggest a subset of OvCa STn+ cells display some CSC features. The effect of the anti-STn antibody-drug conjugates (ADCs) S3F-CL-MMAE and 2G12-2B2-CL-MMAE on OvCa cell viability in vitro and in vivo was also assessed. Treatment with S3F-CL-MMAE reduced the viability of two of three OvCa cell lines in vitro and exposure to either S3F-CL-MMAE or 2G12-2B2-CL-MMAE reduced OVCAR3-derived xenograft volume in vivo, depleting STn+ tumor cells. In summary, STn+ cells demonstrate some stem-like properties and specific therapeutic targeting of STn in ovarian tumors may be an effective clinical strategy to eliminate both STn+ CSC and STn+ non-CSC populations

Humanized anti-STn ADCs inhibit tumor growth in OVCAR3 xenograft models.

<p>(A) Weekly dosing of OVCAR3 xenografts was initiated at Day 0 with 1, 2.5 or 5 mg/kg 2G12-2B2-L0H3-MMAE and 5 mg/kg Isotype Control-MMAE. Groups were terminated when average size of the vehicle-treated group reached ~1400 mm³. * P < 0.05. (B) IHC evaluation of STn expression in vehicle, isotype control-MMAE (5 mg/kg) and 2G12-2B2-L0H3-MMAE (5 mg/kg) treated groups after study termination, (C) Evaluation of treatment of larger tumors (500 mm³) by 5 mg/kg isotype control-MMAE and 2G12-2B2-L0H3-MMAE.</p