Hypothesis-generating evaluation of multi-armoured oncolytic HSV-1 (VG161) in intrahepatic cholangiocarcinoma: pooled insights from multicentre studies

Background Intrahepatic cholangiocarcinoma (ICC) is a highly aggressive malignancy with limited treatment options and poor prognosis, especially for patients who failed standard therapies. Objective To explore the safety, efficacy and immunological mechanisms of the novel edition of oncolytic virus vaccination, VG161, a multiarmed oncolytic herpes simplex virus-1 expressing interleukin (IL)-12, IL-15 and a programmed death-ligand 1 antagonist, in patients with advanced ICC. Design This pooled analysis integrates data from two multicentre clinical studies: a Phase I dose-escalation study and a Phase IIa exploratory study. 24 patients with advanced ICC received ultrasound-guided intratumoral injections of VG161. Multiomics analyses were performed on longitudinal tumour biopsies to evaluate immune modulation. Results The oncolytic virus therapy VG161 was well tolerated and showed encouraging antitumour activity, including improved overall survival versus second-line FOLFOX chemotherapy, even though most patients received VG161 as third-line or later therapy. Notably, patients previously treated with immune checkpoint inhibitors (CPIs) experienced enhanced benefit. Multiomics profiling of longitudinal biopsies revealed significant remodelling of the immunosuppressive tumour microenvironment, with proliferated infiltration of antigen-presenting cells, CD8+ T cell activation and M2-like macrophage depletion. Single-cell and spatial transcriptomics identified epithelial and macrophage subpopulations (Epi-C2 and Macro-C1QC) as potential biomarkers of response and resistance. Conclusion These early-phase findings suggest that VG161 elicits meaningful immune activation in ICC and supports further investigation. By inducing both direct oncolysis and multilayered immune activation, VG161 shows clinical benefit in a heavily pretreated population and holds promise for integration with CPI-based regimens. Validation in larger trials is warranted. Data are available in a public, open access repository. Data are available from the corresponding author upon reasonable request.