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.

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.

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.

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.

A synergetic targeted liposomal system which functionalized with both a tumor identification ligand and an immune targeting ligand was constructed. It could recognize and bind ER-positive breast cancer tissues in a specific way and reduce the macrophage phagocytosis of the nanoparticles.

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.

The flavonol aglycone isorhamnetin shows anti-proliferative activity in a variety of cancer cells. Previous work, from our laboratory showed that isorhamnetin inhibits the proliferation of human esophageal squamous carcinoma Eca-109 cells in vitro, but only after 72 h of exposure. This led us to propose that isorhamnetin exposure induces a cellular stress response that inhibits the antiproliferative and apoptotic effects of the compound during early exposure. To test this hypothesis, the present study examined the effects of isorhamnetin on Eca-109 cells during the first 72 h of exposure. Cell growth was assessed using the trypan blue exclusion assay, and expression of IκBα, NF-κB/p65, NF-κB/p50, phospho-Akt, Bcl-2, COX-2, Mcl-1, Bax, p53 and Id-1 were analyzed by Western blot. During the first 72 h of exposure, NF-κB/p65 and NF-κB/p50 accumulated in nuclei and expression of COX-2, Bcl-2 and Mcl-1 increased. In contrast, expression of IκBα and Bax fell initially but later increased. Expression of phospho-Akt and p53 showed no detectable change during the first 48 h. Pretreatment with the NF-κB inhibitor MG132 before exposure to isorhamnetin blocked the nuclear accumulation of p50 and p65, thereby inhibiting cell proliferation. These results show that during early exposure of Eca-109 cells to isorhamnetin, the NF-κB signaling pathway is activated and COX-2 expression increases, and this increase in expression partially inhibits isorhamnetin-induced apoptosis. Beyond 72 h of exposure, however, the apoptotic effect of isorhamnetin dominates, leading to inhibition of the NF-κB pathway and of cellular proliferation. These results will need to be taken into account when exploring the use of isorhamnetin against cancer in vivo.

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.