Fibroblast Activation Protein-α Responsive Peptide Assembling Prodrug Nanoparticles for Remodeling the Immunosuppressive Microenvironment and Boosting Cancer Immunotherapy.

Checkpoint blockade immunotherapy has broad application prospects in the clinical treatment of malignant tumors. However, the low response rate of the checkpoint blockade is due to low tumor immunogenicity and immunosuppression within the tumor microenvironment. Herein, the authors design an amphiphilic bifunctional PD-1/PD-L1 peptide antagonist PCP, and co-deliver doxorubicin (DOX) and R848 through co-assembly of a multi-agent prodrug (PCP@R848/DOX), which can be specifically cleaved by fibroblast activation protein-α (FAP-α) in the tumor stroma. Upon reaching the tumor tissue, the PCP@R848/DOX prodrug nanostructure is disassembled by FAP-α. The localized release of DOX and R848 triggers immunogenic cell death (ICD) and reprograms tumor-associated macrophages (TAMs) to elicit antitumor immunity. Furthermore, sustained release of PD-1 or PD-L1 peptide antagonists mediates the PD-L1 pathway blockade for further propagated activation of cytotoxic T lymphocytes. Notably, a tumor microenvironment activatable prodrug nanoparticle is presented for triple-modality cancer therapy that functions by simultaneously activating ICD and altering the phenotype of TAMs when combined with PD-1 blockade therapy, which efficiently elicits a strong systemic antitumor immune response. This strategy may emerge as a new paradigm in the treatment of cancer by combination immunotherapy.

Ultrasensitive Gastric Cancer Circulating Tumor Cellular CLDN18.2 RNA Detection Based on a Molecular Beacon.

Gastric cancer (GC) is a major global cancer burden, and only HER2-targeted therapies have been approved in first line clinical therapy. CLDN18.2 has been regarded as a potential therapeutic target for gastrointestinal tumors, and global clinical trials have been in process. Hence, the precise, efficient, and noninvasive detection of CLDN18.2 expression is important for the effective application of this attractive target. A high similarity of protein sequence between CLDN18.1 and -18.2 made RNA become more suitable for the detection of CLDN18.2 expression. In this study, CLDN18.2 molecular beacon (MB) with a stem-loop hairpin structure was optimized by phosphorothioate and 2'-O-methyl for stability and efficiency. The MB could recognize CLDN18.2 RNA rapidly. Its resolution and selectivity has been verified in several model cells, demonstrating that MB can distinguish CLDN18.2 expression in several model cells. Furthermore, it was applied successfully to the circulating tumor cell (CTC) assay. The concordance in the expression of CLDN18.2 between CTCs and tissue biopsy is 100% (negative: 3 vs 3; positive: 7 vs 7), indicating that CLDN18.2 RNA detection in CTCs based on a MB will be a promising approach for searching potential patients to CLDN 18.2 targeted drug.

Boosting the Theranostic Effect of Liposomal Probes toward Prominin-1 through Optimized Dual-Site Targeting.

Ligand-targeting specific liposomal probes are increasingly used as imaging and delivery vehicles for in vivo diagnosis. Thereinto, the ligand variety and density profoundly affect the binding behaviors toward the target. The synergetic effect of different ligands could be achieved only when the optimized molecular-recognition configuration occurred. In this study, we construct a dual-peptides-targeting liposomal probe named BTLS that could synergistically bind two different sites of prominin-1, a cancer stem cell marker. At the distance of 11 Å between the two new peptides, ligands could insert into the hollow pocket of prominin-1 and BTLS could achieve the appropriate spatial structure, showing the strong binding affinity in both cellular and in vivo levels. It is indicated that the design of density-optimized peptide-targeted liposomes could be promising to maximize the multifunctional targeting effects on the cancer theranostics.

Gold nanoparticles enhance antibody effect through direct cancer cell cytotoxicity by differential regulation of phagocytosis.

Ramucirumab is the first FDA-approved monotherapy for advanced gastric cancer. In this study, Ramucirumab (Ab) is attached to gold nanoparticles to enhance uptake efficiency. Gold nanoparticles can induce direct cytotoxic effects to cancer cells in the presence of Ab, while individual Ab or gold nanoparticles don't have such an effective anticancer effect even at extremely high concentrations. Proteomic and transcriptomic analyses reveal this direct cytotoxicity is derived predominantly from Ab-mediated phagocytosis. High affinity immunoglobulin gamma Fc receptor I shows differential up-regulation in gastric cancer cells treated by these nanodrugs compared with Ab, especially for Ab with gold nanorods. Simplified and powerful designs of smart nanoparticles are highly desired for clinical application. The enhancement of Ab accumulation with a simple composition, combined with direct cytotoxic effects specific to cancer cells brought improved therapeutic effects in vivo compared with Ab, which can promote further clinical application of gold nanomaterials in the diagnosis and therapeutics of gastric cancer.

A Novel CD133- and EpCAM-Targeted Liposome With Redox-Responsive Properties Capable of Synergistically Eliminating Liver Cancer Stem Cells.

Cancer stem cells (CSCs) are a small subset of cells that sit atop the hierarchical ladder in many cancer types. Liver CSCs have been associated with high chemoresistance and recurrence rates in hepatocellular carcinoma (HCC). However, as of yet, no satisfactorily effective liver CSC-targeted treatment is available, which drove us to design and investigate the efficacy of a liposome-based delivery system. Here, we introduce a redox-triggered dual-targeted liposome, CEP-LP@S/D, capable of co-delivering doxorubicin (Dox) and salinomycin (Sal) for the synergistic treatment of liver cancer. This system is based on the association of CD133- and EpCAM-targeted peptides to form Y-shaped CEP ligands that were anchored to the surface of the liposome and allowed the selective targeting of CD133+ EpCAM+ liver CSCs. After arriving to the CSCs, the CEP-LP@S/D liposome undergoes endocytosis to the cytoplasm, where a high concentration of glutathione (GSH) breaks its disulfide bonds, thereby degrading the liposome. This then induces a rapid release of Dox and Sal to synergistically inhibit tumor growth. Notably, this effect occurs through Dox-induced apoptosis and concurrent lysosomal iron sequestration by Sal. Interestingly, both in vitro and in vivo studies indicated that our GSH-responsive co-delivery system not only effectively enhanced CSC targeting but also eliminated the non-CSC faction, thereby exhibiting high antitumor efficacy. We believe that the smart liposome nanocarrier-based co-delivery system is a promising strategy to combat liver cancer, which may also lay the groundwork for more enhanced approaches to target other cancer types as well.

Synergetic estrogen receptor-targeting liposome nanocarriers with anti-phagocytic properties for enhanced tumor theranostics.

Multifunctional nanocarriers have been widely applied due to their enhanced effect on tumor therapeutics. Nevertheless, owing to the natural immune clearance mechanisms in living bodies, nanocarriers tend to be eliminated during blood circulation, thereby impeding their effective arrival at the tumor sites. Herein, we constructed a synergetic targeted liposome nanocarrier system named SELS functionalized with both a tumor identification ligand (anti-ER (Estrogen Receptor) antibody) and an immune targeting ligand (Self-Peptide (SP)). The anti-ER antibody could recognize and bind ER-positive breast cancer tissues in a specific way. SP could activate the CD47-SIRPα immune response, which reduced phagocytosis of the nanoparticles by macrophages. Both the enhanced targeting ability and anti-phagocytosis behavior could improve the tumor uptake of the nanocarriers and prevent their immune clearance in living systems. Therefore, drug-loaded SELS enabled improved tumor imaging and therapeutic performance in living systems.

Quantitative proteomic analysis to the first commercialized liposomal paclitaxel nano-platform Lipusu revealed the molecular mechanism of the enhanced anti-tumor effect.

The first nano-platform commercialized as a drug delivery system was a liposomal formulation. The application of liposome technology resolved the issues of paclitaxel (PTX) insolubility and eliminated the use of solvents causing toxic side-effects, which enabled to apply higher drug doses leading to an enhanced drug efficacy. The growth-inhibitory activity of liposome-encapsulated PTX was retained in vitro against a variety of tumor cell. To investigate the drug efficacy in the system biological level, quantitative proteomic analysis was employed to study the molecular mechanism of the anti-tumor effect of Lipusu® (lip) compared with PTX on lung cancer cell A549. The functions of the differential expressed proteins were correlated to the negative effect to cell proliferation due to regulation of hippo pathway and prolonged cell cycle, as well as inhibitory cell exocytosis, which would cause the aggregation of free PTX. This investigation focused on the direct biological effect of lip to cancer cells. It was different from pharmaceutical issues about drug exposure, delivery and distribution which were widely investigated in other traditional studies. It was the first study about the drug effect of lip from the global molecular biological aspect.

Molecular Cancer Imaging in the Second Near-Infrared Window Using a Renal-Excreted NIR-II Fluorophore-Peptide Probe.

In vivo molecular imaging of tumors targeting a specific cancer cell marker is a promising strategy for cancer diagnosis and imaging guided surgery and therapy. While targeted imaging often relies on antibody-modified probes, peptides can afford targeting probes with small sizes, high penetrating ability, and rapid excretion. Recently, in vivo fluorescence imaging in the second near-infrared window (NIR-II, 1000-1700 nm) shows promise in reaching sub-centimeter depth with microscale resolution. Here, a novel peptide (named CP) conjugated NIR-II fluorescent probe is reported for molecular tumor imaging targeting a tumor stem cell biomarker CD133. The click chemistry derived peptide-dye (CP-IRT dye) probe afforded efficient in vivo tumor targeting in mice with a high tumor-to-normal tissue signal ratio (T/NT > 8). Importantly, the CP-IRT probes are rapidly renal excreted (≈87% excretion within 6 h), in stark contrast to accumulation in the liver for typical antibody-dye probes. Further, with NIR-II emitting CP-IRT probes, urethra of mice can be imaged fluorescently for the first time noninvasively through intact tissue. The NIR-II fluorescent, CD133 targeting imaging probes are potentially useful for human use in the clinic for cancer diagnosis and therapy.