Anti-CTGF/PD-1 bispecific antibody Y126S restrains desmoplastic and immunosuppressive microenvironment in pancreatic cancer.

Background: Pancreatic ductal adenocarcinoma (PDAC) is characterized by a desmoplastic and immunosuppressive tumor microenvironment (TME), limiting the efficacy of immune checkpoint inhibitors such as anti-programmed cell death 1 (PD-1).

Methods: This study aimed to evaluate the therapeutic potential of Y126S, a recombinant IgG1/IgG2 hybrid bispecific antibody (BsAb), in reshaping the immunotherapy-resistant TME in PDAC. Orthotopic PDAC and KPC (Kras; Trp53; Pdx1-Cre) mouse models were established and treated with Y126S, α-connective tissue growth factor (CTGF), α-PD-1, or a combination of α-CTGF and α-PD-1. TME remodeling, antibody distribution, and therapeutic efficacy were assessed using flow cytometry, immunohistochemical/Masson staining, atomic force microscopy, positron emission tomography (PET) imaging, distribution analysis, and other experimental techniques.

Results: Here, Y126S was characterized and its antitumor efficacy was evaluated and validated in orthotopic PDAC mice and KPC mouse models. Notably, Y126S significantly remodeled the TME and demonstrated superior tumor-specific accumulation compared with single α-PD-1 treatment, leading to markedly enhanced antitumor efficacy relative to its parental antibodies or their combination. Mechanistically, Y126S suppressed cancer-associated fibroblasts (CAFs) activation, reduced collagen deposition, and downregulated programmed cell death ligand 1 (PD-L1) expression on CAFs by targeting CTGF and enhanced the anti-PD-1-mediated reinvigoration of cytotoxic CD8 T cells, thereby establishing a less desmoplastic and potent tumor-killing microenvironment.

Conclusions: Our findings highlight the potential of Y126S as a promising BsAb-based immunotherapy strategy for PDAC by remodeling the desmoplastic and immunosuppressive TME.