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

Abstract

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