Work

Development of a Novel Anti-Siglec-15 Antibody for Tumor Immunotherapy

Year: 2025

Type: article

Abstract: Purpose: As a novel candidate in cancer immunotherapy, siglec-15-targeting antibodies hold promise for providing alternative therapeutic strategies to tumors unresponsive to programmed death ligand 1 (PD-L1) antibody therapy. To date, pharmacological development targeting siglec-15 has not yet achieved significant breakthroughs or clinical approval. Therefore, this study aims to develop a novel anti-siglec-15 antibody designed to restore tumor immune normalization. Methods: In this study, we constructed a phage immune library derived from lymphoid tissues of lung cancer patients using phage display technology and screened the fully human antibodies against siglec-15 antigen from this library. The antibody affinity was detected by Bio-Layer Interferometry, the binding rate of antibody to positively expressing siglec-15 tumor cells was examined by flow cytometry, and the activity of antibody-mediated killer cells against tumor cells was reflected by Antibody-Dependent Cellular Cytotoxicity (ADCC) action. The blockage of proliferation inhibition caused by siglec-15 antigen by antibodies was investigated by t-lymphocyte proliferation assays, and CD8 + T cells were collected from malignant pleural effusion specimens derived from lung cancer patients to determinewhether antibodies could alleviate the immunosuppression present in the tumor microenvironment (TME). The anti-tumor efficacy of the antibody was investigated in vivo by constructing a zebrafish tumor model and a humanized mouse tumor model. Results: The antibody demonstrated nanomolar affinity and specificity, enhanced antibody-dependent cellular cytotoxicity (ADCC) against tumor cells, reversed T-cell suppression, and reduced CD8 + T-cell exhaustion in vitro analyses. In vivo models confirmed tumor growth inhibition via increased lymphocyte infiltration and activation. Conclusion: Antibody immune libraries from lymphoid tissues of lung cancer patients can screen specific antibodies against siglec-15 target antigens and exert certain biological functions in vitro and in vivo. Plain Language Summary: Following PD-1/PD-L1 blockade, siglec-15 has emerged as a compelling therapeutic target for tumor immune normalization, with its specific antibodies potentially addressing clinical resistance to PD-1 inhibitors. Utilizing phage display technology, we developed a lung cancer patient-derived immune library and isolated a novel anti-siglec-15 antibody exhibiting nanomolar affinity and precise antigen specificity, as rigorously validated through Bio-Layer Interferometry (BLI) and ELISA. Functional characterization demonstrated the antibody’s dual mechanism: enhancing lymphocyte-mediated ADCC against tumor cells while reversing siglec-15-induced suppression of T-cell proliferation. Notably, in vitro analyses of malignant pleural effusions, the antibody significantly reduced CD8 + T-cell exhaustion. We found that anti-siglec-15 recombinant antibodies inhibited tumor growth by increasing lymphocyte infiltration and activation in tumor tissues by constructing a zebrafish tumor model and a PBMC humanized mouse tumor model. These findings provide a theoretical framework for the development of anti-siglec-15 targeting antibody drugs and tumor immunonormalization therapy. Keywords: phage display technology, lymphocyte infiltration, T-cell suppression, malignant pleural effusion, tumor microenvironment

Source: ImmunoTargets and Therapy

DOI: 10.2147/itt.s536009