Self-Reinforced Cancer Targeting (SRCT) Depending on Reciprocally Enhancing Feedback between Targeting and Therapy

Tailored design of NHS-SS-NHS cross-linked chitosan nano-hydrogels for enhanced anti-tumor efficacy by GSH-responsive drug release

The traditional chemotherapeutic agents' disadvantages such as high toxicity, untargeting and poor water solubility lead to disappointing chemotherapy effects, which restricts its clinical application. In this work, novel size-appropriate and glutathione (GSH)-responsive nano-hydrogels were successfully prepared via the active ester method between chitosan (containing -NH2) and cross-linker (containing NHS). Especially, the cross-linker was elaborately designed to possess a disulfide linkage (SS) as well as two terminal NHS groups, namely NHS-SS-NHS. These functionalities endowed chitosan-based cross-linked scaffolds with capabilities for drug loading and delivery, as well as a GSH-responsive mechanism for drug release. The prepared nano-hydrogels demonstrated excellent performance applicable morphology, excellent drug loading efficiency (∼22.5%), suitable size (∼100 nm) and long-term stability. The prepared nano-hydrogels released over 80% doxorubicin (DOX) after incubation in 10 mM GSH while a minimal DOX release less than 25% was tested in normal physiological buffer (pH = 7.4). The unloaded nano-hydrogels did not show any apparent cytotoxicity to A 549 cells. In contrast, DOX-loaded nano-hydrogels exhibited marked anti-tumor activity against A 549 cells, especially in high GSH environment. Finally, through fluorescent imaging and flow cytometry analysis, fluorescein isothiocyanate-labeled nano-hydrogels show obvious specific binding to the GSH high-expressing A549 cells and nonspecific binding to the GSH low-expressing A549 cells. Therefore, with this cross-linking approach, our present finding suggests that cross-linked chitosan nano-hydrogel drug carrier improves the anti-tumor effect of the A 549 cells and may serve as a potential injectable delivery carrier.

A Synergistic Chemoimmunotherapy System Leveraging PD-L1 Blocking and Bioorthogonal Prodrug Activation

Novel strategies to facilitate tumor-specific drug delivery and restore immune attacks remain challenging in overcoming the current limitations of chemoimmunotherapy. An antitumor chemoimmunotherapy system comprising bioorthogonal reaction-ready group tetrazine (TZ) modified with an anti-PD-L1 antibody (αPD-L1TZ) and TZ-activatable prodrug vinyl ether-doxorubicin (DOX-VE) for self-reinforced anti-tumor chemoimmunotherapy is proposed. The αPD-L1TZ effectively disrupts the PD-L1/PD-1 interaction and activates the DOX prodrug in situ through the bioorthogonal click reaction of TZ and VE. Conversely, the activated DOX upregulates PD-L1 on the surface of tumor cells, facilitating tumor accumulation of αPD-L1TZ and enhancing DOX-VE activation. Furthermore, the activated DOX-induced immunogenic cell death of tumor cells, substantially improving the response efficiency of αPD-L1 in an immune-suppressive tumor microenvironment. Thus, PD-L1 blocking and bioorthogonal in situ prodrug activation synergistically enhance the antitumor efficacy of the chemoimmunotherapy system. Therefore, the system significantly enhances αPD-L1 tumor accumulation and prodrug activation and induces a robust immunological memory effect to prevent tumor recurrence and metastasis. Thus, a feasible chemoimmunotherapy combination regimen is presented.

Personalized Targeted Therapeutic Strategies against Oral Squamous Cell Carcinoma. An Evidence-Based Review of Literature

Oral squamous cell carcinoma (OSCC) is the most common type of malignant tumor in the head and neck, with a poor prognosis mainly due to recurrence and metastasis. Classical treatment modalities for OSCC like surgery and radiotherapy have difficulties in dealing with metastatic tumors, and together with chemotherapy, they have major problems related to non-specific cell death. Molecular targeted therapies offer solutions to these problems through not only potentially maximizing the anticancer efficacy but also minimizing the treatment-related toxicity. Among them, the receptor-mediated targeted delivery of anticancer therapeutics remains the most promising one. As OSCC exhibits a heterogeneous nature, selecting the appropriate receptors for targeting is the prerequisite. Hence, we reviewed the OSCC-associated receptors previously used in targeted therapy, focused on their biochemical characteristics and expression patterns, and discussed the application potential in personalized targeted therapy of OSCC. We hope that a better comprehension of this subject will help to provide the fundamental information for OSCC personalized therapeutic planning.