Dual-Membrane-Camouflaged Engineered Bacteria for Targeted Melanoma Therapy

Bacteria have attracted enormous attention in cancer therapy due to their immunoactivating capabilities and ease of genetic engineering. However, clinical advancement is hindered by off-target toxicity, rapid clearance, and low therapeutic efficiency, demanding additional functionalization. Herein, by leveraging the universal adhesive capacity of iron-tannic acid (Fe-TA) networks, a dual-membrane-camouflaged bacterial therapeutic (VNP-AIF@Fe-TA@RH) was fabricated through fusing red blood cell membrane (RM) and PD-1-overexpressing HEK293T cell membrane (HM) on the surface of an attenuated <i>Salmonella typhimmurium</i> strain genetically engineered with apoptosis-inducing factor (AIF)-encoding plasmids. Camouflaged by RM, VNP-AIF@Fe-TA@RH demonstrated prolonged blood circulation and facilitated selective tumor accumulation together with the intrinsic hypoxic tropism of VNP, presenting a remarkable tumor-to-organ accumulation ratio of up to 3.76 × 10⁷-fold. Upon reaching tumor sites, in situ AIF encoding in tumor cells induced enhanced cell apoptosis and subsequently triggered robust antitumor immune responses, which were powered by T cell dysfunction reversing endowed by HM-mediated PD-L1 immune checkpoint blockade. Consequently, the tumor immune microenvironment was effectively remodeled, as evidenced by dendritic cell maturation, effector T cell activation, macrophage phenotypic repolarization, reduced T regulatory cell infiltration, and enhanced production of pro-inflammatory cytokines. Collectively, effective inhibition of bilateral melanoma tumor growth and metastasis was accomplished. This work presented a potent bacteria-based biohybrid therapeutic, inspiring the design of effective alternatives for cancer therapy.