Durvalumab is used to treat a certain type of bladder and urinary tract cancer. It works by helping your immune system fight the cancer. This medication belongs to a class of drugs known as monoclonal antibodies.   Imfinzi is supplied as an infusion for intravenous administration. The recommended dose is 10 mg/kg administered as an intravenous infusion over 60 minutes every 2 weeks until disease progression or unacceptable toxicity. Please see drug label for treatment modifications.