Synchronous targeted delivery of TGF-ß siRNA to stromal and tumor cells elicits robust antitumor immunity against triple-negative breast cancer by comprehensively remodeling the tumor microenvironment.

The poor permeability of therapeutic drugs, limited T-cell infiltration, and strong immunosuppressive tumor microenvironment of triple-negative breast cancer (TNBC) acts as a prominent barrier to the delivery of drugs and immunotherapy including programmed cell death ligand-1 antibody (anti-PD-L1). Transforming growth factor (TGF)-ß, an important cytokine produced by cancer-associated fibroblasts (CAFs) and tumor cells contributes to the pathological vasculature, dense tumor stroma and strong immunosuppressive tumor microenvironment (TME). Herein, a nanomedicine platform (HA-LSL/siTGF-ß) employing dual-targeting, alongside hyaluronidase (HAase) and glutathione (GSH) triggered release was elaborately constructed to efficiently deliver TGF-ß small interference RNA (siTGF-ß). It was determined that this system was able to improve the efficacy of anti-PD-L1. The siTGF-ß nanosystem efficiently silenced TGF-ß-related signaling pathways in both activated NIH 3T3 cells and 4T1 cells in vitro and in vivo. This occurred firstly, through CD44-mediated uptake, followed by rapid escape mediated by HAase in endo/lysosomes and release of siRNA mediated by high GSH concentrations in the cytoplasm. By simultaneous silencing of TGF-ß in stromal and tumor cells, HA-LSL/siTGF-ß dramatically reduced stroma deposition, promoted the penetration of nanomedicines for deep remodeling of the TME, improved oxygenation, T cells infiltration and subsequent anti-PD-L1 deep penetration. The double suppression of TGF-ß has been demonstrated to promote blood vessel normalization, inhibit an epithelial-to-mesenchymal transition (EMT), and further modify the immunosuppressive TME, which was supported by an overall increase in the proportion of dendritic cells and cytotoxic T cells. Further, a reduction in the proportion of immunosuppression cells such as regulatory T cells and myeloid-derived suppressor cells was also observed in the TME. Based on the comprehensive remodeling of the tumor microenvironment by this nanosystem, subsequent anti-PD-L1 therapy elicited robust antitumor immunity. Specifically, this system was able to suppress the growth of both primary and distant tumor while preventing tumor metastasis to the lung. Therefore, the combination of the dual-targeted siTGF-ß nanosystem, alongside anti-PD-L1 may serve as a novel method to enhance antitumor immunotherapy against stroma-rich TNBC.

The programmed site-specific delivery of LY3200882 and PD-L1 siRNA boosts immunotherapy for triple-negative breast cancer by remodeling tumor microenvironment.

Despite the remarkable success of immunotherapies over the past decade, their effectiveness against triple-negative breast cancer (TNBC) is limited to a small subset of patients, mainly due to the low immunogenicity and unfavorable tumor microenvironment. In this study, we successfully constructed a programmed site-specific delivery nanosystem for the combined delivery of transforming growth factor beta (TGF-ß) receptor inhibitor LY3200882 (LY) and PD-L1 siRNA (siPD-L1) to boost anti-tumor immunotherapy. As expected, LY in the outer layer of the nanosystem was released by stimulation of MMP2, and dramatically down-regulated the expression of extracellular matrix (ECM) in the tumor-associated fibroblasts (TAFs), and thus promoted the infiltration of effector T cells and penetration of nanomedicines. Simultaneously, the blockade of TGF-ß by LY also triggered immunogenic cell death (ICD) of tumor cells and induced the maturation of dendritic cells. Moreover, the programmed design provided the siPD-L1/protamine cationic inner core with easier access to tumor cells and TAFs after MMP2-stimulated breakup of the outer layer, down-regulating the expression of PD-L1 in both types of cells. Notably, the synergistic effect of LY and siPD-L1 remarkably enhanced the tumor antigen presentation and immunosuppressive microenvironment remodeling, thus efficiently inhibiting the TNBC growth, metastasis, and recurrence. Therefore, the programmed site-specific delivery nanosystem is a promising drug delivery platform for boosting anti-tumor immunotherapy efficacy for TNBC.

A multiple environment-sensitive prodrug nanomicelle strategy based on chitosan graftomer for enhanced tumor therapy of gambogic acid.

A novel multiple environment-sensitive polymeric prodrug of gambogic acid (GA) based on chitosan graftomer was fabricated for cancer treatment. Folic acid-chitosan conjugates was complexed with thermosensitive amine terminated poly-N-isopropylacrylamide (NH2-PNIPAM) to develop FA-CSPN. Gambogic acid was conjugated with the graftomer via esterification to achieve high drug-loading capacity and controlled drug release. The resulting amphiphilic prodrug, O-(gambogic acid)-N-(folic acid)-N'-(NH2-PNIPAM) chitosan graftomer (GFCP), could self-assemble into micelles. As expected, the micelles were stable and biocompatible, featuring pH-, esterase- and temperature-dependent manner of drug release. Moreover, the anticancer effect studies of GFCP micelles were performed using a tumor-bearing mouse model and cellular assays (tumor cell uptake assay, cytotoxicity and tumor-sphere penetration). Collectively, GFCP micelles show both potential in vivo and in vitro in improving the anticancer effectiveness of GA owing to high loading capacity, targeted tumor accumulation, and multiple tumor microenvironmental responsiveness.