OH2 Oncolytic Viral Therapy in Non-Muscle-Invasive Bladder Cancer

This trial is testing an oncolytic virus therapy called OH2 — a virus that selectively infects and kills cancer cells while also stimulating the immune system — delivered directly into the bladder for patients with high-risk non-muscle-invasive bladder cancer that has not responded to standard treatments. **You may be eligible if...** - You are between 18 and 80 years old - You have high-grade non-muscle-invasive bladder cancer (Ta, T1, or Tis stage) - Your cancer has failed standard bladder instillation therapy (such as BCG) - You still have your bladder (or are not a candidate for bladder removal surgery for other reasons) **You may NOT be eligible if...** - Your cancer has grown into the bladder muscle or spread beyond the bladder - You have active serious infections - You have severe immune system problems - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.