Engineered Ultrasmall Nanoparticle Drug-Immune Conjugates with "Hit and Run" Tumor Delivery to Eradicate Gastric Cancer.

Despite advances by recently approved antibody-drug conjugates in treating advanced gastric cancer patients, substantial limitations remain. Here, several key obstacles are overcome by developing a first-in-class ultrasmall (sub-8-nanometer (nm)) anti-human epidermal growth factor receptor 2 (HER2)-targeting drug-immune conjugate nanoparticle therapy. This multivalent fluorescent core-shell silica nanoparticle bears multiple anti-HER2 single-chain variable fragments (scFv), topoisomerase inhibitors, and deferoxamine moieties. Most surprisingly, drawing upon its favorable physicochemical, pharmacokinetic, clearance, and target-specific dual-modality imaging properties in a "hit and run" approach, this conjugate eradicated HER2-expressing gastric tumors without any evidence of tumor regrowth, while exhibiting a wide therapeutic index. Therapeutic response mechanisms are accompanied by the activation of functional markers, as well as pathway-specific inhibition. Results highlight the potential clinical utility of this molecularly engineered particle drug-immune conjugate and underscore the versatility of the base platform as a carrier for conjugating an array of other immune products and payloads.

Ultrasmall Nanoparticle Delivery of Doxorubicin Improves Therapeutic Index for High-Grade Glioma.

PURPOSE: Despite dramatic growth in the number of small-molecule drugs developed to treat solid tumors, durable therapeutic options to control primary central nervous system malignancies are relatively scarce. Chemotherapeutic agents that appear biologically potent in model systems have often been found to be marginally effective at best when given systemically in clinical trials. This work presents for the first time an ultrasmall (<8 nm) multimodal core-shell silica nanoparticle, Cornell prime dots (or C' dots), for the efficacious treatment of high-grade gliomas. EXPERIMENTAL DESIGN: This work presents first-in-kind renally clearable ultrasmall (<8 nm) multimodal C' dots with surface-conjugated doxorubicin (DOX) via pH-sensitive linkers for the efficacious treatment in two different clinically relevant high-grade glioma models. RESULTS: Optimal drug-per-particle ratios of as-developed nanoparticle-drug conjugates were established and used to obtain favorable pharmacokinetic profiles. The in vivo efficacy results showed significantly improved biological, therapeutic, and toxicological properties over the native drug after intravenous administration in platelet-derived growth factor-driven genetically engineered mouse model, and an EGF-expressing patient-derived xenograft (EGFR PDX) model. CONCLUSIONS: Ultrasmall C' dot-drug conjugates showed great translational potential over DOX for improving the therapeutic outcome of patients with high-grade gliomas, even without a cancer-targeting moiety.

Molecular Engineering of Ultrasmall Silica Nanoparticle-Drug Conjugates as Lung Cancer Therapeutics.

PURPOSE: Small-molecule inhibitors have had a major impact on cancer care. While treatments have demonstrated clinically promising results, they suffer from dose-limiting toxicities and the emergence of refractory disease. Considerable efforts made to address these issues have more recently focused on strategies implementing particle-based probes that improve drug delivery and accumulation at target sites, while reducing off-target effects. EXPERIMENTAL DESIGN: Ultrasmall (<8 nm) core-shell silica nanoparticles, C' dots, were molecularly engineered to function as multivalent drug delivery vehicles for significantly improving key in vivo biological and therapeutic properties of a prototype epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, gefitinib. Novel surface chemical components were used to conjugate gefitinib-dipeptide drug-linkers and deferoxamine (DFO) chelators for therapeutic delivery and PET imaging labels, respectively. RESULTS: Gefitinib-bound C' dots (DFO-Gef-C' dots), synthesized using the gefitinib analogue, APdMG, at a range of drug-to-particle ratios (DPR; DPR = 11-56), demonstrated high stability for DPR values≤ 40, bulk renal clearance, and enhanced in vitro cytotoxicity relative to gefitinib (LD50 = 6.21 nmol/L vs. 3 µmol/L, respectively). In human non-small cell lung cancer mice, efficacious Gef-C' dot doses were at least 200-fold lower than that needed for gefitinib (360 nmoles vs. 78 µmoles, respectively), noting fairly equivalent tumor growth inhibition and prolonged survival. Gef-C' dot-treated tumors also exhibited low phosphorylated EFGR levels, with no appreciable wild-type EGFR target inhibition, unlike free drug. CONCLUSIONS: Results underscore the clinical potential of DFO-Gef-C' dots to effectively manage disease and minimize off-target effects at a fraction of the native drug dose.

High-affinity mutant Interleukin-13 targeted CAR T cells enhance delivery of clickable biodegradable fluorescent nanoparticles to glioblastoma.

Glioblastoma (GBM), the deadliest form of brain cancer, presents long-standing problems due to its localization. Chimeric antigen receptor (CAR) T cell immunotherapy has emerged as a powerful strategy to treat cancer. IL-13-receptor-α2 (IL13Rα2), present in over 75% of GBMs, has been recognized as an attractive candidate for anti-glioblastoma therapy. Here, we propose a novel multidisciplinary approach to target brain tumors using a combination of fluorescent, therapeutic nanoparticles and CAR T cells modified with a targeted-quadruple-mutant of IL13 (TQM-13) shown to have high binding affinity to IL13Rα2-expressing glioblastoma cells with low off-target toxicity. Azide-alkyne cycloaddition conjugation of nanoparticles to the surface of T cells allowed a facile, selective, and high-yielding clicking of the nanoparticles. Nanoparticles clicked onto T cells were retained for at least 8 days showing that the linkage is stable and promising a suitable time window for in vivo delivery. T cells clicked with doxorubicin-loaded nanoparticles showed a higher cytotoxic effect in vitro compared to bare T cells. In vitro and in vivo T cells expressing TQM-13 served as delivery shuttles for nanoparticles and significantly increased the number of nanoparticles reaching brain tumors compared to nanoparticles alone. This work represents a new platform to allow the delivery of therapeutic nanoparticles and T cells to solid tumors.

Ultrasmall Core-Shell Silica Nanoparticles for Precision Drug Delivery in a High-Grade Malignant Brain Tumor Model.

PURPOSE: Small-molecule inhibitors have revolutionized treatment of certain genomically defined solid cancers. Despite breakthroughs in treating systemic disease, central nervous system (CNS) metastatic progression is common, and advancements in treating CNS malignancies remain sparse. By improving drug penetration across a variably permeable blood-brain barrier and diffusion across intratumoral compartments, more uniform delivery and distribution can be achieved to enhance efficacy. EXPERIMENTAL DESIGN: Ultrasmall fluorescent core-shell silica nanoparticles, Cornell prime dots (C' dots), were functionalized with αv integrin-binding (cRGD), or nontargeting (cRAD) peptides, and PET labels (124I, 89Zr) to investigate the utility of dual-modality cRGD-C' dots for enhancing accumulation, distribution, and retention (ADR) in a genetically engineered mouse model of glioblastoma (mGBM). mGBMs were systemically treated with 124I-cRGD- or 124I-cRAD-C' dots and sacrificed at 3 and 96 hours, with concurrent intravital injections of FITC-dextran for mapping blood-brain barrier breakdown and the nuclear stain Hoechst. We further assessed target inhibition and ADR following attachment of dasatinib, creating nanoparticle-drug conjugates (Das-NDCs). Imaging findings were confirmed with ex vivo autoradiography, fluorescence microscopy, and p-S6RP IHC. RESULTS: Improvements in brain tumor delivery and penetration, as well as enhancement in the ADR, were observed following administration of integrin-targeted C' dots, as compared with a nontargeted control. Furthermore, attachment of the small-molecule inhibitor, dasatinib, led to its successful drug delivery throughout mGBM, demonstrated by downstream pathway inhibition. CONCLUSIONS: These results demonstrate that highly engineered C' dots are promising drug delivery vehicles capable of navigating the complex physiologic barriers observed in a clinically relevant brain tumor model.

From Cancer Immunoediting to New Strategies in Cancer Immunotherapy: The Roles of Immune Cells and Mechanics in Oncology.

For the last three decades, the concept of immunoediting has evolved to characterize our increasing understanding of the interactions between cells from the immune system and cancer development. Elucidating the role of immune cells in the progression of cancer has been very challenging due to their dual role; the immune system can either suppress tumor formation by killing cancer cells, or it can also promote tumor growth. Revealing how immune cells are hampered by the tumor microenvironment and how they aid tumor progression has signaled strategies to reverse these effects and control cancer cell growth; this has been the advent of immunotherapy design. More recently, the role of physical forces in the process of immunoediting has been highlighted by multiple studies focusing on understanding how force changes in the stiffness of the extracellular matrix and fluid flow shear stress contribute to tumor development. Using models in vitro that incorporate biomechanical components, it has been shown that these physical aspects are not only important during the formation and growth of primary tumors, but in the metastatic process as well. In this way, we have also gained insight into the interactions occurring within the vascular system, which are highly affected by the dynamics of physical collisions between cells and by shear forces. Here, we review the concept of cancer immunoediting with an emphasis on biomechanics and conclude with a summary on current immunotherapies and potential new strategies.

VE-Cadherin Disassembly and Cell Contractility in the Endothelium are Necessary for Barrier Disruption Induced by Tumor Cells.

During metastasis, breakdown of the endothelial barrier is critical for tumor cell extravasation through blood vessel walls and is mediated by a combination of tumor secreted soluble factors and receptor-ligand interactions. However, a complete mechanism governing tumor cell transendothelial migration remains unclear. Here, we investigate the roles of tumor-associated signals in regulating endothelial cell contractility and adherens junction disassembly leading to endothelial barrier breakdown. We show that Src mediates VE-cadherin disassembly in response to metastatic melanoma cells. Through the use of pharmacological inhibitors of cytoskeletal contractility we find that endothelial cell contractility is responsive to interactions with metastatic cancer cells and that reducing endothelial cell contractility abrogates migration of melanoma cells across endothelial monolayers. Furthermore, we find that a combination of tumor secreted soluble factors and receptor-ligand interactions mediate activation of Src within endothelial cells that is necessary for phosphorylation of VE-cadherin and for breakdown of the endothelial barrier. Together, these results provide insight into how tumor cell signals act in concert to modulate cytoskeletal contractility and adherens junctions disassembly during extravasation and may aid in identification of therapeutic targets to block metastasis.

Immune Cell-Mediated Biodegradable Theranostic Nanoparticles for Melanoma Targeting and Drug Delivery.

Although tremendous efforts have been made on targeted drug delivery systems, current therapy outcomes still suffer from low circulating time and limited targeting efficiency. The integration of cell-mediated drug delivery and theranostic nanomedicine can potentially improve cancer management in both therapeutic and diagnostic applications. By taking advantage of innate immune cell's ability to target tumor cells, the authors develop a novel drug delivery system by using macrophages as both nanoparticle (NP) carriers and navigators to achieve cancer-specific drug delivery. Theranostic NPs are fabricated from a unique polymer, biodegradable photoluminescent poly (lactic acid) (BPLP-PLA), which possesses strong fluorescence, biodegradability, and cytocompatibility. In order to minimize the toxicity of cancer drugs to immune cells and other healthy cells, an anti-BRAF V600E mutant melanoma specific drug (PLX4032) is loaded into BPLP-PLA nanoparticles. Muramyl tripeptide is also conjugated onto the nanoparticles to improve the nanoparticle loading efficiency. The resulting nanoparticles are internalized within macrophages, which are tracked via the intrinsic fluorescence of BPLP-PLA. Macrophages carrying nanoparticles deliver drugs to melanoma cells via cell-cell binding. Pharmacological studies also indicate that the PLX4032 loaded nanoparticles effectively kill melanoma cells. The "self-powered" immune cell-mediated drug delivery system demonstrates a potentially significant advancement in targeted theranostic cancer nanotechnologies.