This study aimed to investigate the antitumour efficacy of maprotiline in mice with melanoma….Maprotiline was found to inhibit the proliferation and migration of B16 cells while increasing cell apoptosis. Importantly, treatment with maprotiline decreased the expression of PD-L1...Our research findings suggest that maprotiline enhances the antitumour immune response in mouse melanoma by inhibiting PD-L1 expression. This study may discover a new PD-L1 inhibitor, providing a novel therapeutic option for the clinical treatment of tumours.