CCL9/CCR1 axis-driven chemotactic nanovesicles for attenuating metastasis of SMAD4-deficient colorectal cancer by trapping TGF-β

SMAD4 deficiency in colorectal cancer(CRC)is highly correlated with liver metastasis and high mortality,yet there are few effective precision therapies available.Here,we show that CCR1^(+)-granulocytic myeloid-derived suppressor cells(G-MDSCs)are highly infiltrated in SMAD4-deficient CRC via CCL15/CCR1 and CCL9/CCR1 axis in clinical specimens and mouse models,respectively.The excessive TGF-β,secreted by tumor-infiltrated CCR1^(+)-G-MDSCs,suppresses the immune response of cytotoxic T lymphocytes(CTLs),thus facilitating metastasis.Hereby,we develop engineered nanovesicles displaying CCR1 and TGFBR2 molecules(C/T-NVs)to chemotactically target the tumor driven by CCL9/CCR1 axis and trap TGF-βthrough TGF-β-TGFBR2 specific binding.Chemotactic C/T-NVs counteract CCR1^(+)-G-MDSC infiltration through competitive responding CCL9/CCR1 axis.C/T-NVs-induced intratumoral TGF-βexhaustion alleviates the TGF-β-suppressed immune response of CTLs.Collectively,C/T-NVs attenuate liver metastasis of SMAD4-deficient CRC.In further exploration,high expression of programmed cell death ligand-1(PD-L1)is observed in clinical specimens of SMAD4-deficient CRC.Combining C/T-NVs with anti-PD-L1 antibody(aPD-L1)induces tertiary lymphoid structure formation with sustained activation of CTLs,CXCL13^(+)-CD4^(+)T,CXCR5^(+)-CD20^(+)B cells,and enhanced secretion of cytotoxic cytokine interleukin-21 and IFN-γaround tumors,thus eradicating metastatic foci.Our strategy elicits pleiotropic antimetastatic immunity,paving the way for nanovesicle-mediated precision immunotherapy in SMAD4-deficient CRC.