7MeERT Enhances Antibody-Drug Conjugate Efficacy in Glioblastoma by Inducing AMPK-p38MAPK-Mediated Non-Canonical Endocytosis of EGFRvIII

INTRODUCTION: Antibody-drug conjugates (ADCs) targeting EGFR variant III (EGFRvIII) hold promise for glioblastoma therapy, but clinical efficacy is limited by poor receptor internalization. METHODS: We evaluated the effects of 7MeERT, a quinoline derivative, on EGFRvIII internalization and the activity of Depatuxizumab Mafodotin (ABT-414) in glioblastoma cells. Western blotting, immunofluorescence, Seahorse assays, and RNA interference were employed to dissect the involved signaling pathways. RESULTS: 7MeERT reduced intracellular ATP levels and activated AMPKα1, which subsequently triggered p38MAPK phosphorylation. This cascade led to the phosphorylation of serine 1015 on EGFRvIII and promoted its internalization via non-canonical endocytosis. The internalization of both EGFRvIII and ABT-414 was confirmed in glioblastoma cells and was shown to be dependent on AMPKα1-p38MAPK. 7MeERT treatment enhanced the cytotoxic efficacy of ABT-414 in EGFRvIII-expressing cells but had no effect in EGFRvIII-negative cells. DISCUSSION: Our findings demonstrate a metabolic mechanism by which 7MeERT promotes non-canonical endocytosis of EGFRvIII, enhancing ADC uptake. The AMPK-p38MAPK-EGFRvIII axis plays a central role in this process. CONCLUSION: 7MeERT enhances EGFRvIII-targeting ADC efficacy in glioblastoma by inducing metabolic stress and triggering AMPK-p38MAPK-mediated non-canonical endocytosis. This strategy may improve ADC delivery in tumors with impaired receptor internalization.