Invasive bladder cancer can be treated through immunotherapy involving Bacillus Calmette-Guérin (BCG), but some 40%-60% of treated patients suffer progression or recurrence. In an effort to find more effective treatments for refractory disease, researchers at the Université de Sherbrooke and its hospital research center have engineered an oncolytic vesicular stomatitis virus encoding granulocyte-macrophage colony-stimulating factor (VSVd51-GM-CSF).