Given that vascular endothelial growth factor (VEGF) and placental growth factor (PIGF), over-expressed in breast cancer cells and M2-like tumor-associated macrophages (M2-TAMs) within tumor microenvironment (TME), work synergistically and independently in mediating tumor progression and immunosuppression, combinatorial immune-based approaches targeting them are expected to be a potent therapeutic modality for patients. Here, polyethylene glycol (PEG) and mannose doubly modified trimethyl chitosan (PEG = MT) along with citraconic anhydride grafted poly (allylamine hydrochloride) (PC)-based nanoparticles (NPs) (PEG = MT/PC NPs) with dual pH-responsiveness were developed to deliver VEGF siRNA (siVEGF)/PIGF siRNA (siPIGF) to both M2-TAMs and breast cancer cells for antitumor immunotherapy. With prolonged blood circulation and intelligent pH-sensitivity, PEG = MT/PC NPs were highly accumulated in tumor tissues and then internalized in M2-TAMs and breast cancer cells via mannose-mediated active targeting and passive targeting, respectively. With the charge-reversal of PC, PEG = MT/PC NPs presented effective endosomal/lysosomal escape and intracellular siRNA release, resulting in efficient gene silencing. Due to the synergism between siVEGF and siPIGF in anti-proliferation of tumor cells and reversal of the TME from pro-oncogenic to anti-tumoral, PEG = MT/PC/siVEGF/siPIGF NPs (PEG = MT/PC/siV-P NPs) exerted robust suppression of breast tumor growth and lung metastasis. This combination strategy may provide a promising alternative for breast cancer therapy.

鉴于血管内皮生长因子（VEGF）和胎盘生长因子（PIGF）在肿瘤微环境（TME）内的乳腺癌细胞和M2样肿瘤相关巨噬细胞（M2-TAMs）中过表达，因此在介导中起协同作用和独立作用肿瘤进展和免疫抑制，针对它们的基于组合免疫的方法有望成为患者的有效治疗手段。在这里，聚乙二醇（PEG）和甘露糖双修饰的三甲基壳聚糖（PEG = MT）以及基于柠康酸酐接枝的聚（烯丙胺盐酸盐）（PC）的纳米颗粒（NPs）（PEG = MT / PC NPs）具有双重pH响应已开发出可将VEGF siRNA（siVEGF）/ PIGF siRNA（siPIGF）递送至M2-TAM和乳腺癌细胞以进行抗肿瘤免疫治疗的方法。分别通过甘露糖介导的主动靶向和被动靶向。通过PC的电荷逆转，PEG = MT / PC NPs表现出有效的内体/溶酶体逃逸和细胞内siRNA释放，从而导致有效的基因沉默。由于siVEGF和siPIGF在肿瘤细胞的抗增殖以及TME从致癌性转变为抗肿瘤性方面的协同作用，PEG = MT / PC / siVEGF / siPIGF NPs（PEG = MT / PC / siV-P NPs ）强烈抑制了乳腺肿瘤的生长和肺转移。这种联合策略可能为乳腺癌治疗提供有希望的替代方法。