Abstract
BACKGROUND: High-risk ALK-mutant neuroblastoma (NB) presents challenges due to drug resistance and an immunosuppressive tumour microenvironment (TME). Combining molecular targeted therapy with adoptive cell therapy offers a potential therapeutic strategy. OBJECTIVE: To investigate the effects of alectinib, an ALK inhibitor, with disialoganglioside 2 (GD2) chimeric antigen receptor T (CAR-T) cell therapy in overcoming immune evasion in ALK-mutant NB. METHODS: Interferon gamma-induced programmed death-ligand 1 (PD-L1) expression and ALK signalling were analysed in ALK-mutant NB cells. The combination of alectinib and GD2 CAR-T cells was assessed in vitro, including sequential co-culture assays, and in vivo in an ALK-mutant xenograft model with multiple treatment arms. RESULTS: Alectinib suppressed PD-L1 expression by inhibiting ALK downstream pathways, including STAT3 and ERK1/2 phosphorylation. In vitro studies showed enhanced anti-tumour efficacy of GD2 CAR-T cells in combination with alectinib, with synergistic effect becoming evident in sequential coculture models. In vivo, the combination therapy reduced tumour growth, extended survival, and was associated with decreased PD-L1 expression and increased CAR-T cell infiltration. CONCLUSION: Alectinib enhances the efficacy of GD2 CAR-T therapy in ALK-mutant NB primarily by attenuating PD-L1-mediated immune evasion, supporting its potential as a combinatorial therapeutic strategy.