Immunosuppressive JAG2+ tumor-associated neutrophils hamper PD-1 blockade response in ovarian cancer by mediating the differentiation of effector regulatory T cells.

Background: Tumor-associated neutrophils (TANs) play a critical role in modulating immune responses and exhibit significant heterogeneity. Our previous study demonstrated that jagged canonical Notch ligand 2 (JAG2)⁺ TANs were associated with an immunosuppressive microenvironment in high-grade serous ovarian cancer (HGSOC), but the underlying mechanism remains unclear. This study aimed to elucidate the role of JAG2⁺ TANs in tumor immunosuppressive microenvironment in HGSOC.

Methods: HGSOC samples were collected, with 274 samples constituting two independent cohorts (training and validation cohorts) and an additional 30 samples utilized to establish patient-derived tumor organoids (PDTOs). We characterized the number and phenotype of JAG2⁺ TANs by multiplex immunohistochemistry, flow cytometry, and single-cell RNA sequencing (scRNA-seq). We investigated the biological functions of JAG2 in immune evasion using in vitro co-culture systems, flow cytometry, tumor-bearing mouse models, and PDTOs.

Results: JAG2⁺ TANs expressed elevated levels of immunosuppressive molecules, including programmed cell death ligand 1 and CD14, and had independent prognostic value for the overall survival of patients with HGSOC. scRNA-seq analysis revealed that JAG2⁺ TANs exhibited a terminally mature phenotype. The infiltration of JAG2⁺ TANs was positively correlated with the abundance of effector regulatory T cells (eTregs). Interaction with JAG2⁺ TANs skewed CD4⁺ T cells towards an eTreg phenotype, a process that was suppressed by the Notch inhibitor LY3039478 and induced by recombinant Jagged2. Furthermore, we demonstrated that JAG2⁺ TANs enhanced Notch signaling activation, ultimately promoting recombination signal binding protein for immunoglobulin kappa J region (RBPJ)-induced differentiation of naïve CD4⁺ T cells into eTregs. Clinically, JAG2⁺ TANs could serve as a biomarker for assessing immunotherapy resistance in various solid tumors. Pharmacological targeting of Notch signaling with LY3039478 or JAG2 neutralization antibodies enhanced the efficacy of programmed cell death protein 1 (PD-1) monoclonal antibodies (mAbs) in both xenograft and PDTO models.

Conclusions: The emergence of JAG2⁺ TANs is crucial for the differentiation of eTregs, which triggers immune evasion and resistance to anti-PD-1 therapy. Inhibiting Notch signaling with LY3039478 or JAG2 neutralization antibodies may overcome this anti-PD-1 resistance in HGSOC.