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INTRODUCTION The median survival of gliobastoma (GBM) patients remains less than two years despite aggressive treatments. Current targeted GBM therapies demonstrate initial therapeutic benefit; however, patients relapse due to therapeutic resistance and failure to eliminate GBM cells at the invasive margin. Therefore, we propose a two-prong approach: first, target pathologic disruption of the blood brain barrier (BBB) via exposure of neural ECM rather than disease markers to overcome therapy-resistant GBM; and second, designing therapeutic payloads that extracellularly spread throughout the tumor volume. METHODS Variable Lymphocyte Receptors (VLRs, a lamprey-derived antigen recognition system) were identified with high specificity for neural ECM. Candidate VLRs underwent further refinement using ex vivo tissue staining. Utilizing pathologic disruption of BBB as an approach for targeting GBM was confirmed in vivo with intracranial murine glioblastoma models. Finally, an immunogenic peptide was attached via a cleavable linker to the neural ECM binding VLRs for conditional release extracellularly to spread throughout the tumor. RESULTS The lead neural ECM-binding VLR candidate, named P1C10, demonstrates diffuse binding to parenchymal neural ECM, without detectable binding to other tissues. P1C10 demonstrates nanomolar affinity for neural ECM, and preferentially accumulates in intracranial GL261 and U87 murine GBM models. Finally, P1C10-targeted doxorubicin-loaded liposomes significant increased survival of mice with intracranial GBM. In additional studies, treating murine GBM models with a P1C10 VLR linked to an immunogenic peptide reduced GBM proliferation and increased infiltration of cytotoxic T cells. CONCLUSIONS We present proof-of-concept demonstration for targeting intracranial GBM via neural ECM exposed at pathological BBB disrupted sites. Additionally, P1C10 neural ECM-targeting VLR delivers chemotherapy-loaded nanoparticles and immunogenic peptides designed to spread extracellularly throughout the tumor. Thus, this novel strategy links a physiological ECM targeting scheme with extracellular-released therapeutics to treat primary GBM, and has potential for delivering therapies to other CNS diseases with pathological BBB.