Intranasal delivery of lipid-based nanoparticle encapsulating CXCR7 agonist improves PD-L1 blockade efficacy in glioblastoma

[Background] Glioblastoma (GBM) is characterized by limited treatment options and poor survival outcomes. Glioblastoma-associated macrophages (GAMs) are crucial factors that tailor the immunosuppressive tumor microenvironment (TME). Our previous study revealed that VUF11207 (VUF), a CXCR7 agonist, effectively recaptured the efficacy of the anti-PD-L1 antibody (alphaPD-L1) in GBM-bearing mice through inhibited CXCL12 release from tumor to transmit signals to GAMs. However, the efficacy of VUF may be hindered by poor brain delivery due to the blood-brain barrier (BBB). [Methods] To optimize the drug delivery, we developed lipid-based nanoparticle (LNP) formulations with a non-invasive naso-to-brain delivery manner by spray. We applied an in vivo brain-penetration evaluation platform to assess their ability to bypass BBB. The effect of LNP-encapsulated VUF (VUF@LNP) was then assessed by observing its molecular effect and the response to alphaPD-L1 treatment in the animal model. [Results] The particle size, surface charge, and shape structure of the lipid nanoparticles was controlled by mixing lipids. Studies of LNP formulations encapsulated with Evans blue (EB) have shown that the highest brain penetration efficiency is achieved with LNPs exhibiting a positive charge when synthesized at a 1,2-Dioleoyl-3-trimethylammonium-propane (DOTAP) to 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) ratio of 1:4. Next, the in vivo bioluminescent and fluorescent imaging confirmed that DiL-labelled VUF@LNP with intranasal delivery was able to accumulate in brain tumor sites. Comparing with systemic and intranasal administration of VUF, intranasal delivery of VUF@LNP significantly improved the survival outcome of GBM-bearing mice. Intranasal delivery of VUF@LNP combined with alphaPD-L1 treatment markedly prolonged survival in comparison with intranasal delivery of free VUF with alphaPD-L1 treatment. No significant body weight changes were observed, supporting the biosafety of VUF@LNP. In terms of biological aspects, intranasal-administrating VUF@LNP significantly reduced CXCL12 and pERK1/2 levels in TME, leading to PD-L1 downregulation in GAMs and increased CD8⁺ T-cell infiltration in comparison with systemic-administrating VUF and intranasal-administrating LNP control. [Conclusion] Together, these findings indicated that intranasal VUF@LNP provides a BBB-bypassing, non-invasive strategy for delivering CXCR7 agonists to reprogram the immune TME. This approach may be a potential nanotherapeutic platform for combinatorial immunomodulation against GBM.