A novel intranasal peptide vaccine inhibits non-small cell lung cancer with KRAS mutation.

KRAS mutations occur commonly in the lung and can lead to the development of non-small cell lung cancer (NSCLC). While the mutated KRAS protein is a neoantigen, it usually does not generate an effective anti-tumor immune response on mucosal/epithelial surfaces. Despite this, mutated KRAS remains a potential target for immunotherapy since immune targeting of this protein in animal models has been effective at eliminating tumor cells. We attempted to develop a KRAS vaccine using mutated and wild-type KRAS peptides in combination with a nanoemulsion (NE) adjuvant. The efficacy of this approach was tested in an inducible mutant KRAS-mouse lung tumor model. Animals were immunized intranasally using NE with KRAS peptides. These animals had decreased CD4+FoxP3+ T cells in both lymph nodes and spleen. Immunized animals also showed higher IFN-γ and IL-17a levels to mutated KRAS that were produced by CD8+ T cells and enhancement in KRAS-specific Th1 and Th17 responses that persisted for 3 months after the last vaccination. Importantly, the immunized animals had significantly decreased tumor incidence compared to control animals. In conclusion, a mucosal approach to KRAS vaccination demonstrated the ability to induce local KRAS-specific immune responses in the lung and resulted in reduced tumor incidence.

Delicate Hybrid Laponite-Cyclic Poly(ethylene glycol) Nanoparticles as a Potential Drug Delivery System.

The objective of the study was to explore the feasibility of a new drug delivery system using laponite (LAP) and cyclic poly(ethylene glycol) (cPEG). Variously shaped and flexible hybrid nanocrystals were made by both the covalent and physical attachment of chemically homogeneous cyclized PEG to laponite nanodisc plates. The size of the resulting, nearly spherical particles ranged from 1 to 1.5 µm, while PEGylation with linear methoxy poly (ethylene glycol) (mPEG) resulted in fragile sheets of different shapes and sizes. When infused with 10% doxorubicin (DOX), a drug commonly used in the treatment of various cancers, the LAP-cPEG/DOX formulation was transparent and maintained liquid-like homogeneity without delamination, and the drug loading efficiency of the LAP-cPEG nano system was found to be higher than that of the laponite-poly(ethylene glycol) LAP-mPEG system. Furthermore, the LAP-cPEG/DOX formulation showed relative stability in phosphate-buffered saline (PBS) with only 15% of the drug released. However, in the presence of human plasma, about 90% of the drug was released continuously over a period of 24 h for the LAP-cPEG/DOX, while the LAP-mPEG/DOX formulation released 90% of DOX in a 6 h burst. The results of the cell viability assay indicated that the LAP-cPEG/DOX formulation could effectively inhibit the proliferation of A549 lung carcinoma epithelial cells. With the DOX concentration in the range of 1-2 µM in the LAP-cPEG/DOX formulation, enhanced drug effects in both A549 lung carcinoma epithelial cells and primary lung epithelial cells were observed compared to LAP-mPEG/DOX. The unique properties and effects of cPEG nanoparticles provide a potentially better drug delivery system and generate interest for further targeting studies and applications.

Shielded α-Nucleophile Nanoreactor for Topical Decontamination of Reactive Organophosphate.

Here, we describe a nanoscale reactor strategy with a topical application in the therapeutic decontamination of reactive organophosphates (OPs) as chemical threat agents. It involves functionalization of poly(amidoamine) dendrimer through a combination of its partial PEG shielding and exhaustive conjugation with an OP-reactive α-nucleophile moiety at its peripheral branches. We prepared a 16-member library composed of two α-nucleophile classes (oxime, hydroxamic acid), each varying in its reactor valency (43-176 reactive units per nanoparticle), and linker framework for α-nucleophile tethering. Their mechanism for OP inactivation occurred via nucleophilic catalysis as verified against P-O and P-S bonded OPs including paraoxon-ethyl (POX), malaoxon, and omethoate by 1H NMR spectroscopy. Screening their reactivity for POX inactivation was performed under pH- and temperature-controlled conditions, which resulted in identifying 13 conjugates, each showing shorter POX half-life up to 2 times as compared to a reference Dekon 139 at pH 10.5, 37 °C. Of these, 10 conjugates were further confirmed for greater efficacy in POX decontamination experiments performed in two skin models, porcine skin and an artificial human microtissue. Finally, a few lead conjugates were selected and demonstrated for their biocompatibility in vitro as evident with lack of skin absorption, no inhibition of acetylcholinesterase (AChE), and no cytotoxicity in human neuroblastoma cells. In summary, this study presents a novel nanoreactor library, its screening methods, and identification of potent lead conjugates with potential for therapeutic OP decontamination.

Measuring the Adhesion Forces for the Multivalent Binding of Vancomycin-Conjugated Dendrimer to Bacterial Cell-Wall Peptide.

Multivalent ligand-receptor interaction provides the fundamental basis for the hypothetical notion that high binding avidity relates to the strong force of adhesion. Despite its increasing importance in the design of targeted nanoconjugates, an understanding of the physical forces underlying the multivalent interaction remains a subject of urgent investigation. In this study, we designed three vancomycin (Van)-conjugated dendrimers G5(Van) n ( n = mean valency = 0, 1, 4) for bacterial targeting with generation 5 (G5) poly(amidoamine) dendrimer as a multivalent scaffold and evaluated both their binding avidity and physical force of adhesion to a bacterial model surface by employing surface plasmon resonance (SPR) spectroscopy and atomic force microscopy. The SPR experiment for these conjugates was performed in a biosensor chip surface immobilized with a bacterial cell-wall peptide Lys-d-Ala-d-Ala. Of these, G5(Van)4 bound most tightly with a KD of 0.34 nM, which represents an increase in avidity by 2 or 3 orders of magnitude relative to a monovalent conjugate G5(Van)1 or free vancomycin, respectively. By single-molecule force spectroscopy, we measured the adhesion force between G5(Van) n and the same cell-wall peptide immobilized on the surface. The distribution of adhesion forces increased in proportion to vancomycin valency with the mean force of 134 pN at n = 4 greater than 96 pN at n = 1 at a loading rate of 5200 pN/s. In summary, our results are strongly supportive of the positive correlation between the avidity and adhesion force in the multivalent interaction of vancomycin nanoconjugates.

Oritavancin Retains a High Affinity for a Vancomycin-Resistant Cell-Wall Precursor via Its Bivalent Motifs of Interaction.

Despite its potent antibacterial activities against drug-resistant Gram-positive pathogens, oritavancin remains partially understood with respect to its primary mode of hydrogen bond interaction with a cell-wall peptide regarding the role of its lipophilic 4'-chlorobiphenyl moiety. Here we report a surface plasmon resonance (SPR) study performed in two cell-wall model surfaces, each prepared by immobilization with a vancomycin-susceptible Lys-d-Ala-d-Ala or vancomycin-resistant Lys-d-Ala-d-Lac peptide. Analysis of binding kinetics performed on the peptide surface showed that oritavancin bound ∼100-1000-fold more tightly than vancomycin on each model surface. Ligand competition experiments conducted by SPR and fluorescence spectroscopy provided evidence that such affinity enhancement can be attributed to its 4'-chlorobiphenyl moiety, possibly through a hydrophobic interaction that led to a gain of free energy with a contribution from enthalpy as suggested by a variable-temperature SPR experiment. On the basis of these findings, we propose a model for the bivalent motifs of interaction of oritavancin with cell-wall peptides, by which the drug molecule can retain a strong interaction even with the vancomycin-resistant peptide. In summary, this study advances our understanding of oritavancin and offers new insight into the significance of bivalent motifs in the design of glycopeptide antibiotics.

Photocontrolled Release of Doxorubicin Conjugated through a Thioacetal Photocage in Folate-Targeted Nanodelivery Systems.

Despite their proven ability for precise and targeted release, nanoplatform systems for photocontrolled delivery often face formidable synthetic challenges, in part due to the paucity of advanced linker strategies. Here, we report on a novel linker strategy using a thioacetal ortho-nitrobenzaldehyde (TNB) cage, demonstrating its application for delivery of doxorubicin (Dox) in two nanoscale systems. This photocleavable linker, TNB(OH), which presents two identical arms, each terminated with a hydroxyl functionality, was prepared in a single step from 6-nitroveratraldehyde. TNB(OH) was used to cross-link Dox to a folate receptor (FAR)-targeting poly(amidoamine) dendrimer conjugate G5(FA)n=5.4(Dox)m=5.1, and also used to prepare an upconversion nanocrystal (UCN) conjugate, UCN-PPIX@(Dox)(G5FA), a larger core/shell nanostructure. In this core/shell nanostructure, the UCN core emits UV and visible light luminescence upon near-infrared (NIR) excitation, allowing for the photocleavage of the TNB linker as well as the photostimulation of protoporphyrin IX (PPIX) coupled as a cytotoxic photosensitizer. Drug-release experiments performed in aqueous solutions with long-wavelength ultraviolet A (UVA) light showed that Dox release occurred rapidly from its TNB linked form or from its dendrimer conjugated form with comparable decay kinetics. Cellular toxicity studies in FAR-overexpressing KB carcinoma cells demonstrated that each nanoconjugate lacked intrinsic cytotoxicity until exposed to UVA or NIR (980 nm) (for the UCN nanoconjugate), which resulted in induction of potent cytotoxicity. In summary, this new TNB strategy offers synthetic convenience in drug conjugation chemistry with the ability for the temporal control of drug activation at the delivery site.

Control of an Unusual Photo-Claisen Rearrangement in Coumarin Caged Tamoxifen through an Extended Spacer.

The use of coumarin caged molecules has been well documented in numerous photocaging applications including for the spatiotemporal control of Cre-estrogen receptor (Cre-ERT2) recombinase activity. In this article, we report that 4-hydroxytamoxifen (4OHT) caged with coumarin via a conventional ether linkage led to an unexpected photo-Claisen rearrangement which significantly competed with the release of free 4OHT. The basis for this unwanted reaction appears to be related to the coumarin structure and its radical-based mechanism of uncaging, as it did not occur in ortho-nitrobenzyl (ONB) caged 4OHT that was otherwise linked in the same manner. In an effort to perform design optimization, we introduced a self-immolative linker longer than the ether linkage and identified an optimal linker which allowed rapid 4OHT release by both single-photon and two-photon absorption mechanisms. The ability of this construct to actively control Cre-ERT2 mediated gene modifications was investigated in mouse embryonic fibroblasts (MEFs) in which the expression of a green fluorescent protein (GFP) reporter dependent gene recombination was controlled by 4OHT release and measured by confocal fluorescence microscopy and flow cytometry. In summary, we report the implications of this photo-Claisen rearrangement in coumarin caged compounds and demonstrate a rational linker strategy for addressing this unwanted side reaction.

A Thioacetal Photocage Designed for Dual Release: Application in the Quantitation of Therapeutic Release by Synchronous Reporter Decaging.

Despite the immense potential of existing photocaging technology, its application is limited by the paucity of advanced caging tools. Here, we report on the design of a novel thioacetal ortho-nitrobenzaldehyde (TNB) dual arm photocage that enabled control of the simultaneous release of two payloads linked to a single TNB unit. By using this cage, which was prepared in a single step from commercial 6-nitroverataldehyde, three drug-fluorophore conjugates were synthesized: Taxol-TNB-fluorescein, Taxol-TNB-coumarin, and doxorubicin-TNB-coumarin, and long-wavelength UVA light-triggered release experiments demonstrated that dual payload release occurred with rapid decay kinetics for each conjugate. In cell-based assays performed in vitro, dual release could also be controlled by UV exposure, resulting in increased cellular fluorescence and cytotoxicity with potency equal to that of unmodified drug towards the KB carcinoma cell line. The extent of such dual release was quantifiable by reporter fluorescence measured in situ and was found to correlate with the extent of cytotoxicity. Thus, this novel dual arm cage strategy provides a valuable tool that enables both active control and real-time monitoring of drug activation at the delivery site.

Effect of alternative aluminum adjuvants on the absorption and immunogenicity of HPV16 L1 VLPs in mice.

Aluminum adjuvants are commonly used in prophylactic vaccines to enhance antigen immunogenicity through induction of high-titer antibody responses. Three major forms of aluminum adjuvants with substantially different physical and chemical properties have been described: aluminum phosphate (AlPO(4)), aluminum hydroxide (AlOH) and amorphous aluminum hydroxyphosphate sulfate (AAHS). Here we describe the effect of these different aluminum adjuvants on the formulation and subsequent immunogenicity in mice of virus-like particles (VLPs) consisting of the L1 protein of Human Papillomavirus (HPV) Type 16. Electron microscopy demonstrated that the physical appearance of the phosphate-containing aluminum adjuvants was markedly different from that of aluminum hydroxide. All three aluminum adjuvants were found to display unique surface charge profiles over a range of pH, while AAHS demonstrated the greatest inherent capacity for adsorption of L1 VLPs. These differences were associated with differences in immunogenicity: anti-HPV L1 VLP responses from mice immunized with AAHS-formulated HPV16 vaccine were substantially greater than those produced by mice immunized with the same antigen formulated with aluminum hydroxide. In addition, HPV L1 VLPs formulated on AAHS also induced a substantial interferon-gamma secreting T cell response to L1 peptides indicating the potential for an enhanced memory response to this antigen. These results indicate that the chemical composition of aluminum adjuvants can have a profound influence on the magnitude and quality of the immune response to HPV VLP vaccines.