We are doing this study to find out if a medical technology called the Signatera blood test can help doctors and patients determine the best course of treatment for bladder cancer after the patient has a radical cystectomy (removal of the bladder and surrounding lymph nodes). The Signatera test is used to detect cancer DNA in the blood before cancer can be seen using imaging (like MRI or CT scans).

Bladder Cancer

Adults ages 18+ who:

• Are diagnosed with urothelial cancer of the bladder
• Had a radical cystectomy (RC) surgery at least 3 weeks, but no more than 12 weeks, before joining the study
• Have no evidence of remaining disease after RC surgery
• Have not had any postoperative/adjuvant systemic therapy or radiation
• Have never been treated with any PD-1 or PD-L1 axis inhibitors

For more information, contact the study team at nick.jeffries@duke.edu.

If you choose to join this study, you will have a blood sample analyzed using the Signatera technology.

If your Signatera test result is positive for cancer DNA, you will get a random assignment (like a coin flip) to 1 of 2 groups. You will either:

• Take a single immunotherapy drug called nivolumab; OR
• Take a combination of nivolumab and another immunotherapy drug called relatlimab

Participants in either of these groups will get the study drugs once every 4 weeks for up to 12 doses.

If your Signatera test result is negative for cancer DNA, you will also get a random assignment to 1 of 2 groups. You will either:

• Take nivolumab; OR
• Not take any drugs and continue to be monitored with periodic Signatera blood tests for up to 2 years

If you are assigned to take nivolumab, you will get this drug once every 4 weeks for up to 12 doses. If you are assigned to be monitored with the Signatera blood test and later have a positive result during monitoring, you will begin treatment with nivolumab and get up to 12 doses.