Alendronate/cRGD-Decorated Ultrafine Hyaluronate Dot Targeting Bone Metastasis

Development of pH-Responsive Hyaluronic Acid-Conjugated Cyclodextrin Nanoparticles for Chemo-/CO-Gas Dual Therapy

In this study, we fabricated γ-cyclodextrin (γCD)-based nanoparticles (NPs) for dual antitumor therapy. First, γCD (the backbone biopolymer) was chemically conjugated with low-molecular-weight hyaluronic acid (HA; a tumoral CD44 receptor-targeting molecule) and 3-(diethylamino)propylamine (DEAP; a pH-responsive molecule), termed as γCD-(DEAP/HA). The obtained γCD-(DEAP/HA) self-assembled in aqueous solution, producing the γCD-(DEAP/HA) NPs. These NPs efficiently entrapped paclitaxel (PTX; an antitumor drug) and triiron dodecacarbonyl (FeCO; an endogenous cytotoxic gas molecule) via hydrophobic interactions between PTX and FeCO with the unprotonated DEAP molecules in γCD-(DEAP/HA) and a possible host-guest interaction in the γCD rings. The release of PTX and FeCO from the NPs resulted from particle destabilization at endosomal pH, probably owing to the protonation of DEAP in the NPs. In vitro studies using MCF-7 tumor cells demonstrated that these NPs were efficiently internalized by the cells expressing CD44 receptors and enhanced PTX/FeCO-mediated tumor cell apoptosis. Importantly, local light irradiation of FeCO stimulated the generation of cytotoxic CO, resulting in highly improved tumor cell death. We expect that these NPs have potential as dual-modal therapeutic candidates with enhanced antitumor activity in response to acidic pH and local light irradiation.

Pheophorbide A-Mediated Photodynamic Therapy Potentiates Checkpoint Blockade Therapy of Tumor with Low PD-L1 Expression

Although the immune checkpoint blockade (ICB) has made a great success in cancer immunotherapy, the overall response rate to the ICB, such as anti-programmed death ligand 1 (PD-L1) therapy, remains only at 20-30%. One major reason is the low expression level of the immune checkpoint in a certain type of tumor cells and its insufficient activation of the host immune system. Herein, we reported a cyclic RGD (cRGD)-modified liposomal delivery system loading the anti-PD-L1 antibody and the photosensitizer pheophorbide A (Pa), allowing a targeting of the low PD-L1 expressing 4T1 mouse breast cancer cells through the recognition of an overexpression of α_vβ₃ integrin on the tumor cells. The Pa-mediated photodynamic therapy (PDT) elevated the expression of PD-L1 on the tumor cells. PDT, in combination with the anti-PD-L1 therapy, promoted the activation and maturation of dendritic cells as well as the infiltration of cytotoxic T lymphocytes, resulting in the augmented antitumor immune response for the enhanced therapeutic effect. These results demonstrated the combined therapeutic effects of PDT and ICB on the tumor with low PD-L1 levels. Our study suggested that an increase in the PD-L1 expression in tumor cells by PDT would be a promising adjuvant treatment to overcome the ICB irresponsiveness.

Research progress of bone-targeted drug delivery system on metastatic bone tumors

Bone metastases are common in malignant tumors and the effect of conventional treatment is limited. How to effectively inhibit tumor bone metastasis and deliver the drug to the bone has become an urgent issue to be solved. While bone targeting drug delivery systems have obvious advantages in the treatment of bone tumors. The research on bone-targeted anti-tumor therapy has made significant progress in recent years. We introduced the related tumor pathways of bone metastases. The tumor microenvironment plays an important role in metastatic bone tumors. We introduce a drug-loading systems based on different environment-responsive nanocomposites for anti-tumor and anti-metastatic research. According to the process of bone metastases and the structure of bone tissue, we summarized the information on bone-targeting molecules. Bisphosphate has become the first choice of bone-targeted drug delivery carrier because of its affinity with hydroxyapatite in bone. Therefore, we sought to summarize the bone-targeting molecule of bisphosphate to identify the modification effect on bone-targeting. And this paper discusses the relationship between bisphosphate bone targeting molecular structure and drug delivery carriers, to provide some new ideas for the research and development of bone-targeting drug delivery carriers. Targeted therapy will make a more outstanding contribution to the treatment of tumors.

Hypoxia-Responsive Azobenzene-Linked Hyaluronate Dot Particles for Photodynamic Tumor Therapy

In this study, we developed ultra-small hyaluronate dot particles that selectively release phototoxic drugs into a hypoxic tumor microenvironment. Here, the water-soluble hyaluronate dot (dHA) was covalently conjugated with 4,4′-azodianiline (Azo, as a hypoxia-sensitive linker) and Ce6 (as a photodynamic antitumor agent), producing dHA particles with cleavable Azo bond and Ce6 (dHA-Azo-Ce6). Importantly, the inactive Ce6 (self-quenched state) in the dHA-Azo-Ce6 particles was switched to the active Ce6 (dequenched state) via the Azo linker (–N=N–) cleavage in a hypoxic environment. In vitro studies using hypoxia-induced HeLa cells (treated with CoCl₂) revealed that the dHA-Azo-Ce6 particle enhanced photodynamic antitumor inhibition, suggesting its potential as an antitumor drug candidate in response to tumor hypoxia.

Progress of Phototherapy Applications in the Treatment of Bone Cancer

Bone cancer including primary bone cancer and metastatic bone cancer, remains a challenge claiming millions of lives and affecting the life quality of survivors. Conventional treatments of bone cancer include wide surgical resection, radiotherapy, and chemotherapy. However, some bone cancer cells may remain or recur in the local area after resection, some are highly resistant to chemotherapy, and some are insensitive to radiotherapy. Phototherapy (PT) including photodynamic therapy (PDT) and photothermal therapy (PTT), is a clinically approved, minimally invasive, and highly selective treatment, and has been widely reported for cancer therapy. Under the irradiation of light of a specific wavelength, the photosensitizer (PS) in PDT can cause the increase of intracellular ROS and the photothermal agent (PTA) in PTT can induce photothermal conversion, leading to the tumoricidal effects. In this review, the progress of PT applications in the treatment of bone cancer has been outlined and summarized, and some envisioned challenges and future perspectives have been mentioned. This review provides the current state of the art regarding PDT and PTT in bone cancer and inspiration for future studies on PT.

Endosomal pH-Responsive Fe-Based Hyaluronate Nanoparticles for Doxorubicin Delivery

In this study, we report pH-responsive metal-based biopolymer nanoparticles (NPs) for tumor-specific chemotherapy. Here, aminated hyaluronic acid (aHA) coupled with 2,3-dimethylmaleic anhydride (DMA, as a pH-responsive moiety) (aHA-DMA) was electrostatically complexed with ferrous chloride tetrahydrate (FeCl₂/4H₂O, as a chelating metal) and doxorubicin (DOX, as an antitumor drug model), producing DOX-loaded Fe-based hyaluronate nanoparticles (DOX@aHA-DMA/Fe NPs). Importantly, the DOX@aHA-DMA/Fe NPs improved tumor cellular uptake due to HA-mediated endocytosis for tumor cells overexpressing CD44 receptors. As a result, the average fluorescent DOX intensity observed in MDA-MB-231 cells (with CD44 receptors) was ~7.9 × 10² (DOX@HA/Fe NPs, without DMA), ~8.1 × 10² (DOX@aHA-DMA_0.36/Fe NPs), and ~9.3 × 10² (DOX@aHA-DMA_0.60/Fe NPs). Furthermore, the DOX@aHA-DMA/Fe NPs were destabilized due to ionic repulsion between Fe²⁺ and DMA-detached aHA (i.e., positively charged free aHA) in the acidic environment of tumor cells. This event accelerated the release of DOX from the destabilized NPs. Our results suggest that these NPs can be promising tumor-targeting drug carriers responding to acidic endosomal pH.