Abstract LB329: Overcoming the blood-brain barrier to potentiate GD2-CAR T therapy using P-selectin-targeted nanomedicine

Abstract Pediatric brain tumors are the leading cause of cancer-related death in children, and high-grade malignancies such as diffuse intrinsic pontine glioma (DIPG) and medulloblastoma (MB) remain intractable. DIPG is inoperable due to its brainstem location and diffuse infiltration, while MB therapy (surgery, craniospinal irradiation, chemotherapy) carries recurrence and long-term neurotoxicity. Progress is further constrained by the blood-brain barrier (BBB), which prevents most systemic therapies from reaching the tumor site. To overcome these challenges, we engineered radiation-guided, P-selectin-targeted PLGA-PEG- (SO3) 2 nanoparticles (sNPs) encapsulating the multikinase inhibitor zotiraciclib (TG02) and explored a combination therapy using GD2-CAR T cells to further enhance therapeutic efficacy. sNPs were fabricated via microfluidic mixing, and surface sulfation, mimicking endogenous P-selectin ligand, was confirmed by X-ray photoelectron spectroscopy. Physicochemical properties, stability, hemocompatibility, and drug release kinetics were characterized. BBB transport was evaluated using a 3D tumor-on-a-chip model, and therapeutic efficacy was assessed in both 2D monolayers and 3D tumor models generated from patient-derived pediatric brain tumor cell lines. sNPs exhibited favorable colloidal properties (hydrodynamic diameter ∼100 nm, polydispersity index ∼0. 1, negative ζ-potential), achieved high encapsulation efficiency with a ∼60% formulation yield, and demonstrated sustained release under physiological conditions. Radiation-induced P-selectin upregulation on DIPG and MB tumor cells, as well as angiogenic endothelium, significantly enhances sNP tumor accumulation. Notably, combination treatment with sNP encapsulating TG02 and GD2-CAR T cells markedly outperformed either monotherapy, resulting in reduced tumor growth and diminished immune evasion in 3D tumor models. Overall, this work demonstrates a BBB-penetrant, tumor-selective nanomedicine strategy that enhances the efficacy of GD2-CAR T therapy in pediatric brain tumors. By integrating radiation guidance, targeted drug delivery, and cellular immunotherapy, this platform addresses key barriers in pediatric neuro-oncology and supports further development for DIPG and MB. Citation Format: Giuseppe Longobardi, Adan Miari, Yulia Liubomirski, Ester Buderovsky, Anat Globerson Levin, Ronit Satchi-Fainaro. Overcoming the blood-brain barrier to potentiate GD2-CAR T therapy using P-selectin-targeted nanomedicine abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts) ; 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86 (8Suppl): Abstract nr LB329.