Engineered allogeneic stem cells orchestrate T lymphocyte driven immunotherapy in immunosuppressive leptomeningeal brain metastasis

Abstract Background Immune-checkpoint inhibitors have shown clinical benefit in non-small cell lung cancer (NSCLC) derived brain metastasis (BM), however, their efficacy in lung to leptomeningeal brain metastasis (LLBM) remains poor. Methods A paired matched RNA expression dataset of patients with NSCLCs and BMs was analyzed to idenfiy BM specific suppressive tumor microenvironment (TME) features. Next, we created immune-competent LLBM mouse models that mimic clinical LLBM. We evaluated the efficacy of intrathecal (IT) delivery of allogeneic stem cells (SCs) engineered to release single-chain variable fragment anti-PD-1 (scFvPD-1). To enhance tumor cell killing and subsequent modulation of the immune TME, we explored the therapeutic activity of dual SCs releasing oncolytic herpes simplex virus (oHSV) and scFvPD-1 and profiled immune and metabolic consequences. Results RNA sequencing analysis of primary NSCLCs and BMs revealed an immune-suppressive TME with reduced immune cells and increased PD-1+ T cells in BMs. We showed significantly decreased immune cells and increased PD-1+ T cells in the TME of LLBM compared to primary NSCLC tumors in LLBM mouse tumor models. Next, we showed that locoregional IT treatment with SC releasing scFvPD-1, but not conventional systemic injection of anti-PD-1 antibody, suppressed tumor growth and improved survival in our immune-competent LLBM models. Furthermore, dual SCs releasing oHSV and scFvPD-1 (SC-oHSV/scFvPD-1) enhanced therapeutic outcomes by inducing oHSV-mediated immunogenic cell death, activating anti-tumor T cell signaling, and disrupting oxidative phosphorylation, which sensitized tumors to cisplatin. Conclusion Locoregional delivery of SC-oHSV/scFvPD-1 effectively targets the immune-suppressive TME in LLBM, providing a promising strategy for treating LLBM.