Patrys Limited announced new pre-clinical data for its lead candidate, PAT-DX1. The studies provide critical mechanistic data which explains PAT-DX1's ability to cross the blood-brain barrier (BBB), via the equilibrative nucleoside transporter 2 (ENT2) pathway. This data will support the company’s planned Investigational New Drug (IND) filing to clinically test PAT-DX1 against brain tumours and metastases as well as other cancers. The investigation was conceived, designed, and led by Dr. James Hansen and Dr. Jiangbing Zhou of the Yale School of Medicine. They initially completed an in vitro study that highlighted ENT2's role in transporting PAT-DX1 across a model of the human BBB, and showed that co-treatment with a small molecule inhibitor of ENT2 blocks this transport. A transwell membrane model (composed of human brain endothelial cells and normal human astrocytes adhered to a membrane) tested the ability of PAT-DX1 to cross the BBB in the presence or absence of an ENT2 inhibitor. In absence of the ENT2 inhibitor, PAT-DX1 crossed the BBB efficiently, while other molecules of similar molecular weight were blocked. The addition of the ENT2 inhibitor significantly impaired PAT-DX1 transport across the BBB, demonstrating that PAT-DX1 crosses the BBB via the ENT2 pathway. Following this finding, Dr. Hansen and Dr. Zhou completed a new animal study that confirmed that PAT-DX1 crosses the BBB and localises to orthotopic brain tumours in mice, and that co-treatment of mice with a small molecule inhibitor of ENT2 blocks this activity. The new animal study was conducted with a highly aggressive human glioblastoma (GBM) tumour explant to generate brain tumours in mice. Mice (4 per group) were randomised to tail vein treatment with either (1) Control vehicle; (2) Fluorescently-labelled PAT-DX1; or (3) Fluorescently-labelled PAT-DX1 + small molecule ENT2 inhibitor. Twenty-four hours after treatment the localisation of PAT-DX1 to brain tumours was visualised by the fluorescence signal. Strong fluorescence signal was detected in the brain tumours in mice treated with PAT-DX1 alone, and this signal was reduced by >50% in mice co-treated with ENT2 inhibitor. These findings confirm the results from the transwell model. The new study contributes to efforts to identify and optimize mechanisms of action for PAT-DX1, which supports the clinical development of the company’s broader portfolio. The study data strengthens the planned IND filing, provides biologic rationale to advance PAT-DX1 to commence clinical testing, particularly against brain tumours and metastases, and forms part of the data package that underpins future strategic discussions.