G-quadruplex RNA Based PROTAC Enables Targeted Degradation of RNA Binding Protein FMRP for Tumor Immunotherapy.

Fragile X mental retardation protein (FMRP), an RNA binding protein (RBP), is aberrantly hyper-expressed in human tumors and plays an essential role in tumor invasion, metastasis and immune evasion. However, there is no small-molecule inhibitor for FMRP so far. In this study, we developed the first FMRP-targeting degrader based on PROteolysis TArgeting Chimera (PROTAC) technology and constructed a heterobifunctional PROTAC through linking a FMRP-targeting G-quadruplex RNA (sc1) to a von Hippel-Lindau (VHL)-targeting ligand peptide (named as sc1-VHLL). Sc1-VHLL specifically degraded endogenous FMRP via ubiquitination pathway in both mouse and human cancer cells. The FMRP degradation significantly changed the secretion pattern of cancer cells, resulting in higher expression of pro-inflammatory cytokine and smaller amounts of immunomodulatory contents. Furthermore, sc1-VHLL, when encapsulated into ionizable liposome nanoparticles (LNP) efficiently targeted tumor site and degraded FMRP in cancer cells. In CT26 tumor-bearing mouse model, FMRP degradation within tumors substantially promoted the infiltration of lymphocytes and CD8 T cells and reduced the proportion of Treg cells, reshaping the proinflammatory tumor microenvironment and accordingly transforming cold tumor into hot tumor. When combined with immune checkpoint blockade (ICB) therapy, sc1-VHLL based treatment remarkably inhibited the tumor growth.

Surgical tumor-derived nanoplatform targets tumor-associated macrophage for personalized postsurgical cancer immunotherapy.

Directly activating CD8+ T cells within the tumor through antigen-presenting cells (APCs) hold promise for tumor elimination. However, M2-like tumor-associated macrophages (TAMs), the most abundant APCs in tumors, hinder CD8+ T cell activation due to inefficient antigen cross-presentation. Here, we demonstrated a personalized nanotherapeutic platform using surgical tumor-derived galactose ligand-modified cancer cell membrane (CM)-coated cysteine protease inhibitor (E64)-loaded mesoporous silica nanoparticles for postsurgical cancer immunotherapy. The platform targeted M2-like TAMs and released E64 within lysosomes, which reshaped antigen cross-presentation and directly activated CD8+ T cells, thus suppressing B16-OVA melanoma growth. Furthermore, this platform, in combination with anti-PD-L1 antibodies, enhanced the therapeutic efficacy and substantially inhibited 4T1 tumor growth. CMs obtained from surgically resected tumors were used to construct a personalized nanotherapeutic platform, which, in synergy with immune checkpoint blockade (ICB), effectively inhibited postsurgical tumor recurrence in 4T1 tumor. Our work offered a robust, safe strategy for cancer immunotherapy and prevention of postsurgical tumor recurrence.