Introduction: Temozolomide (TMZ) is the first-line chemotherapeutic option to treat glioma; however, its efficacy and clinical application are limited by its drug resistance properties. Polo-like kinase 1 (PLK1)-targeted therapy causes G2/M arrest and increases the sensitivity of glioma to TMZ. Therefore, to limit TMZ resistance in glioma, an angiopep-2 (A2)-modified polymeric micelle (A2PEC) embedded with TMZ and a small interfering RNA (siRNA) targeting PLK1 (siPLK1) was developed (TMZ-A2PEC/siPLK). Materials and Methods: TMZ was encapsulated by A2-PEG-PEI-PCL (A2PEC) through the hydrophobic interaction, and siPLK1 was complexed with the TMZ-A2PEC through electrostatic interaction. Then, an angiopep-2 (A2) modified polymeric micelle (A2PEC) embedding TMZ and siRNA targeting polo-like kinase 1 (siPLK1) was developed (TMZ-A2PEC/siPLK). Results: In vitro experiments indicated that TMZ-A2PEC/siPLK effectively enhanced the cellular uptake of TMZ and siPLK1 and resulted in significant cell apoptosis and cytotoxicity of glioma cells. In vivo experiments showed that glioma growth was inhibited, and the survival time of the animals was prolonged remarkably after TMZ-A2PEC/siPLK1 was injected via their tail vein. Discussion: The results demonstrate that the combination of TMZ and siPLK1 in A2PEC could enhance the efficacy of TMZ in treating glioma.

Tumor recurrence remains the major cause of management failure after surgical resection of glioblastoma (GBM). Immunotherapy has the potential to effectively eradicate tumors and trigger immune memory to prevent tumor recurrence but not improve the outcomes of GBM patients. Here, an injectable, reactive oxygen species-degradable therapeutic hydrogel (ADU-AAV-PD1@Gel), capable of sustained local release of soluble PD-1 (sPD-1) and stimulator of interferon gene (STING) agonist ADU-S100 (ADU), is developed and applied in a GBM surgical resection model. Adeno-associated virus serotype 9 is employed to stably express sPD-1 blocking the PD-1/PD-L1 pathway. Concomitantly, the released ADU activates the STING pathway to improve tumor immunogenicity and response to therapy. This therapeutic hydrogel combined with radiotherapy (RT) effectively promotes sustained T cells infiltration and restores T cells effector function, which exhibits a robust antitumor immune response and significantly suppresses tumor growth. Moreover, ADU-AAV-PD1@Gel combined with RT treatment can also induce a long-term immune memory to prevent GBM recurrence. As a result, ADU-AAV-PD1@Gel provides a novel strategy for effective radioimmunotherapy of GBM relapse post-resection.

Glioblastoma (GBM) is one of the most lethal forms of human cancer, with very few long-term survivors. In addition to surgery, chemotherapy is still an important strategy. Unfortunately, GBM chemotherapy faces two main challenges: first, in GBM, epidermal growth factor receptor (EGFR) overexpression results in chemoresistance; second, temozolomide (TMZ) lacks target specificity, which can lead to a reduction in the concentration and side effects in GBM. Nowadays, with the development of nanomedicine systems for applications in tumor therapies, increasing anticancer efficacy and reducing side effects with multi-drug delivery are huge advantages. In this study, pH-sensitive and GBM-targeting nanovesicle (Tf-PEG-PAE(SS)) was fabricated. The chemotherapy drug (TMZ) and EGFR inhibitor (EGFR-siRNA) were co-encapsulated in the nanocarrier, and their anticancer outcomes were investigated in detail. In vitro experiments have shown that the nanocarrier transports TMZ and EGFR-siRNA efficiently into U87 cells, causing a vigorous apoptotic response by silencing the proliferative EGFR gene and increasing the drug concentration of TMZ simultaneously. An experimental study in mice bearing orthotropic glioma revealed that the accumulated nanocarriers in the tumor site could inhibit the tumor growth and prolong the mice survival remarkably through the intracranial injection of Tf-PEG-PAE(SS)/TMZ@siEGFR. The drug co-delivery system could extend the blood circulation time and offer a new strategy to treat glioblastoma.

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