Connexin hemichannel blockade by abEC1.1 disrupts glioblastoma progression, suppresses invasiveness, and reduces hyperexcitability in preclinical models

Background: Connexin (Cx) hemichannels (HCs) contribute to glioblastoma (GBM) progression by facilitating intercellular communication and releasing pro-tumorigenic molecules, including ATP and glutamate. Methods: The efficacy of abEC1.1, a monoclonal antibody that inhibits Cx26, Cx30, and Cx32 HCs, was assessed in vitro by measuring invasion capability, dye and Ca²⁺ uptake, glutamate and ATP release in patient-derived GBM cultures or organoids. Adeno-associated virus (AAV)-mediated antibody gene delivery, or convection-enhanced delivery (CED) of the purified antibody, was used in vivo to test the effect on tumor growth and animal survival, using a syngeneic GBM mouse model. The ability of the antibody to affect glioma-related hyperexcitability was evaluated by patch-clamp recordings in a 2D co-culture model comprising astrocytes and neurons isolated from mouse hippocampi, seeded with GL261 cells. Results: abEC1.1 suppressed GBM cell invasion, reducing gliotransmitter release, and impairing tumor progression. In patient-derived GBM cultures, abEC1.1 significantly decreased cell migration and ATP/glutamate release. In vivo, AAV-mediated antibody gene delivery or CED of the purified antibody reduced tumor burden and prolonged survival in the GL261 syngeneic mouse model of GBM. Furthermore, abEC1.1 mitigated glioma-induced excitatory synaptic activity in the 2D co-culture model, suggesting a dual role in tumor control and hyperexcitability suppression. Conclusions: Our findings establish Cx HC inhibition as a promising therapeutic avenue in GBM and highlight abEC1.1 as a potential candidate for clinical translation.