Leveraging Carnitine-functionalized Lipid Nanocarrier based Targeted Delivery of A1874 PROTAC for Glioblastoma.

Abstract

Purpose: Glioblastoma(GBM) is highly aggressive and therapeutically refractory brain malignancy. Despite maximal intervention, patient prognosis remains dismal. A major obstacle in its management is the limited permeation of therapeutic agents across the blood-brain barrier(BBB), further intensified by resistance to standard chemotherapy such as temozolomide(TMZ). Proteolysis-targeting chimeras(PROTACs), offer new opportunities by enabling selective degradation of oncogenic proteins. A1874, a heterobifunctional molecule, has demonstrated potent, selective degradation of oncogenic driver-BRD4 in pancreatic, breast, and colon cancer. BRD4 drives GBM cell proliferation, survival, and resistance to therapy; therefore, we investigated the therapeutic potential of A1874 in brain cancer.

Methods: Herein, we developed brain-targeted self-nanoemulsifying drug delivery system, termed PRONano, designed to enhance the targeted delivery of A1874. The system is functionalized with Palmitoyl-DL-carnitine chloride(PC) to facilitate transport across the BBB. Physicochemical characterization was performed to assess particle size. In-vitro cytotoxicity, qualitative and quantitative cellular uptake was analyzed. Mechanistic validation was conducted using western blot and qPCR, while 3D spheroid assay was employed to assess efficacy in tumor-mimicking microenvironment.

Results: PRONano exhibited nanoscale particle size and significantly enhanced intracellular uptake of A1874. Formulation exhibited enhanced cytotoxicity in temozolomide-sensitive and resistant GBM cells. Effective BRD4 protein degradation was identified in the Western blot. PRONano significantly inhibited 3-D spheroid tumor growth suggesting better penetration and efficacy in tumor-like microenvironment.

Conclusions: PRONano is brain-targeted, rationally designed nanoformulation which can overcome major A1874 delivery constraints. This strategy augmented PROTAC delivery and therapeutic potential in GBM, supporting future preclinical development.