Abstract
<title>Abstract</title> <p> Neuroblastoma (NB) is the commonest extracranial childhood cancer with devastating prognosis for patients who relapse after intensive maintenance treatment. Although EZH2 inhibitors can enhance the tumour immune microenvironment in adult cancers, the mechanisms by which EZH2 improves immunotherapy remain poorly understood. Analysis of publicly available gene expression datasets from NB patient samples revealed negative correlations between EZH2 expression and several natural killer (NK) cell ligands, suggesting that EZH2 may repress NK-cell ligand expression in NB cells thereby preventing NK cell recognition and tumour elimination. Our data illustrate that inhibition of EZH2 in NB increases the expression of ULBP superfamily member ligands. Functionally, EZH2 inhibition increased NK cell-mediated cytotoxicity in <italic>vitro</italic> , with further enhancement following the addition of anti-GD2 immunotherapy. Combined treatment with an EZH2 inhibitor and anti-GD2 monoclonal antibody (mAb) enhanced antibody-dependent cellular cytotoxicity (ADCC) across a range of anti-GD2 concentrations, with the greatest benefit observed at lower antibody doses. These findings demonstrate that EZH2 inhibition exerts direct anti-tumour effects while increasing susceptibility to NK cell-mediated cytotoxicity and potentiating anti-GD2 immunotherapy. Together, these data warrant further investigation of this combination approach in neuroblastoma. </p>