Lymphotropic Virotherapy Engages DC and High Endothelial Venule Inflammation to Mediate Cancer In Situ Vaccination

Intratumor (IT) inoculation of the rhino:poliovirus chimera, PVSRIPO, yielded objective radiographic responses with long-term survival in 20% of patients with recurrent glioblastoma (rGBM). PVSRIPO infects dendritic cells (DCs) and sets up non-cytopathogenic viral (v)RNA replication, which triggers sustained type-I IFN (IFN-I) signaling and antitumor T cell priming. Here we identify IFN-I signaling in glioma-draining cervical lymph nodes (cLN) as a mediator of polio virotherapy. Transient IFN-I signaling after IT therapy was rescued by cervical perilymphatic injection (CPLI) of PVSRIPO, targeting cLN directly. Dual-site (IT+CPLI) PVSRIPO induced profound inflammatory reprogramming of cLN, enhanced vRNA replication and IFN-I signaling in DCs and High Endothelial Venules (HEV), augmented anti-glioma efficacy in mice, and was associated with T cell activation in rGBM patients. A Ph2 clinical trial of IT+CPLI PVSRIPO is ongoing (NCT06177964). This work implicates the lymphatic system as a novel virotherapy target and demonstrates the CPLI concept to complement brain tumor immunotherapy. Overall design: hCD155tg C57BL/6 mice were implanted with CT2A glioma cells and treated with immunotherapeutic human rhinovirus-poliovirus chimera PVSRIPO in one of four combinations of mock or RIPO intratumorally (IT, 7 and 10 days post implantation) and paralymphatically (CPLI, 10 and 13 days post implantation) with deep and superficial cervical lymph nodes harvested for RNA sequencing.