Glioblastoma treatment with multifunctional nanodrug inhibiting laminin-411 activates local immune response, increases survival of mice and reveals AI-selected immune molecular pathways

Introduction: Cancer microenvironment influences tumor growth, invasion, and escape from immune surveillance. Glioblastoma (GBM) extracellular matrix (ECM) especially laminins play an important role in tumor progression. We previously observed a correlation in GBM samples from 130 patients between increased expression of ECM laminin-411 (alpha4beta1gamma1) and faster tumor recurrence with decreased patient survival. Laminin-411 is a basement membrane component that can also modulate immune response through Notch signaling. We developed novel nanoconjugate (NC) blocking laminin-411 that can activate GBM local immune system after brain delivery. Methods: NC was based on non-toxic poly (beta-L-malic acid, P) with covalently attached antisense oligonucleotides (AON) against laminin-411 alpha4 and beta1 chains, as well as trileucine (LLL) peptide for endosomal escape, AP-2 peptide for blood-brain barrier (BBB) crossing and GBM cell targeting. The NC was thoroughly characterized and was intravenously administered to mice (5 injections) with intracranial syngeneic GL261 GBM. The NC selected for treatment had the structure [P/mPEG5000(2%)/LLL(40%)/AON(alpha4beta1)(2.0%)/AP-2(2%)]. Tumor RNA sequencing (RNA-seq) was analyzed by bioinformatics with artificial intelligence and validated for select genes by immunohistochemistry. Immune cell populations were analyzed by flow cytometry. Results: NC treatment in vivo suppressed GBM growth and significantly prolonged animal survival. RNA-sec analysis after treatment with NC suppressing tumor laminin-411 suggested anti-tumor effect with upregulation of apoptotic Casp3, Ifng, Tnf, Il1a, and Il1b genes and reduction of glioma proliferation markers and oncogenes EGFR, c-Myc, Klf4, Irf4, and Ki-67, as well as Notch ligand Dll3. Ingenuity pathway analysis artificial intelligence module AI interpret predicted activation of inflammatory pathways involved in cell signaling during immune responses, pathways related to adhesion and migration of immune cells, and general immune response. In agreement with these data, protein validation showed decreased Ki-67 and Dll3, and increased T cell marker CD4, inflammatory markers IFNgamma and TNFalpha, and anti-tumor M1 macrophage marker NOS2/iNOS. Interestingly, the immunostaining for markers of GBM stem cells, CD133 and nestin, was markedly decreased upon treatment. Flow cytometry also suggested activation of immune response after NC administration. Conclusion: We describe a novel GBM treatment strategy via NC crossing BBB and targeting critical ECM and immune components of tumor microenvironment that are largely independent of heterogeneous genetic mutations in glioblastoma. Support: NIH grants R01 CA284247, R01 CA188743, R01 CA206220, R01 CA209921, R01 EY013431